Update bundled libpng to version 1.6.17

Merged in the upstream version, which obsoleted many of the local
patches. The remaining diff to clean 1.6.17 is archived in the
qtpatches.diff file.

Change-Id: Ibe6f69d9002adb1ad1c4037670a3a4358ad1a18e
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

30 files changed, 17669 insertions, 8827 deletions

diff --git a/src/3rdparty/libpng.pri b/src/3rdparty/libpng.pri
index 7ac1910..0ff3483 100644
--- a/src/3rdparty/libpng.pri
+++ b/src/3rdparty/libpng.pri
@@ -1,5 +1,5 @@
 DEFINES *= QT_USE_BUNDLED_LIBPNG
-!isEqual(QT_ARCH, i386):!isEqual(QT_ARCH, x86_64):DEFINES += PNG_NO_ASSEMBLER_CODE
+DEFINES += PNG_ARM_NEON_OPT=0
 INCLUDEPATH += $$PWD/libpng
 SOURCES += $$PWD/libpng/png.c \
   $$PWD/libpng/pngerror.c \
diff --git a/src/3rdparty/libpng/ANNOUNCE b/src/3rdparty/libpng/ANNOUNCE
index dbc2ed1..131e0aa 100644
--- a/src/3rdparty/libpng/ANNOUNCE
+++ b/src/3rdparty/libpng/ANNOUNCE
@@ -1,5 +1,4 @@
-
-Libpng 1.5.10 - March 29, 2012
+Libpng 1.6.17 - March 26, 2015
 
 This is a public release of libpng, intended for use in production codes.
 
@@ -8,52 +7,61 @@ Files available for download:
 Source files with LF line endings (for Unix/Linux) and with a
 "configure" script
 
-   libpng-1.5.10.tar.xz (LZMA-compressed, recommended)
-   libpng-1.5.10.tar.gz
-   libpng-1.5.10.tar.bz2
+   libpng-1.6.17.tar.xz (LZMA-compressed, recommended)
+   libpng-1.6.17.tar.gz
 
 Source files with CRLF line endings (for Windows), without the
 "configure" script
 
-   lpng1510.7z  (LZMA-compressed, recommended)
-   lpng1510.zip
+   lpng1617.7z  (LZMA-compressed, recommended)
+   lpng1617.zip
 
 Other information:
 
-   libpng-1.5.10-README.txt
-   libpng-1.5.10-LICENSE.txt
+   libpng-1.6.17-README.txt
+   libpng-1.6.17-LICENSE.txt
+   libpng-1.6.17-*.asc (armored detached GPG signatures)
 
-Changes since the last public release (1.5.9):
+Changes since the last public release (1.6.16):
 
-  Removed two useless #ifdef directives from pngread.c and one from pngrutil.c
-  Always put the CMAKE_LIBRARY in "lib" (removed special WIN32 case).
-  Removed empty vstudio/pngstest directory (Clifford Yapp).
-  Eliminated redundant png_push_read_tEXt|zTXt|iTXt|unknown code from
-    pngpread.c and use the sequential png_handle_tEXt, etc., in pngrutil.c;
-    now that png_ptr->buffer is inaccessible to applications, the special
-    handling is no longer useful.
-  Fixed bug with png_handle_hIST with odd chunk length (Frank Busse).
-  Added PNG_SAFE_LIMITS feature to pnglibconf.dfa and code in pngconf.h
-    to reset the user limits to safe ones if PNG_SAFE_LIMITS is defined.
-    To enable, use "CPPFLAGS=-DPNG_SAFE_LIMITS_SUPPORTED" on the configure
-    command or put "#define PNG_SAFE_LIMITS_SUPPORTED" in pnglibconf.h.
-  Revised the SAFE_LIMITS feature to be the same as the feature in libpng16.
-  Added information about the new limits in the manual.
-  Updated Makefile.in
-  Removed unused "current_text" members of png_struct and the png_free()
-    of png_ptr->current_text from pngread.c
-  Fixed PNG_LIBPNG_BUILD_BASE_TYPE definition.
-  Fixed CMF optimization of non-IDAT compressed chunks, which was added at
-    libpng-1.5.4.  It sometimes produced too small of a window.
-  Reject all iCCP chunks after the first, even if the first one is invalid.
-  Added palette-index checking. Issue a png_benign_error() if an invalid
-    index is found.
-  Revised example.c to put text strings in a temporary character array
-    instead of directly assigning string constants to png_textp members.
-    This avoids compiler warnings when -Wwrite-strings is enabled.
-  Prevent PNG_EXPAND+PNG_SHIFT doing the shift twice.
-  Revised png_set_text_2() to avoid potential memory corruption (fixes
-    CVE-2011-3048).
+  Removed duplicate PNG_SAFE_LIMITS_SUPPORTED handling from pngconf.h
+  Corrected the width limit calculation in png_check_IHDR().
+  Removed user limits from pngfix. Also pass NULL pointers to
+    png_read_row to skip the unnecessary row de-interlace stuff.
+  Added testing of png_set_packing() to pngvalid.c
+  Regenerated configure scripts in the *.tar distributions with libtool-2.4.4
+  Implement previously untested cases of libpng transforms in pngvalid.c
+  Fixed byte order in 2-byte filler, in png_do_read_filler().
+  Made the check for out-of-range values in png_set_tRNS() detect
+    values that are exactly 2^bit_depth, and work on 16-bit platforms.
+  Merged some parts of libpng-1.6.17beta01 and libpng-1.7.0beta47.
+  Added #ifndef __COVERITY__ where needed in png.c, pngrutil.c and
+    pngset.c to avoid warnings about dead code.
+  Do not build png_product2() when it is unused.
+  Display user limits in the output from pngtest.
+  Eliminated the PNG_SAFE_LIMITS macro and restored the 1-million-column
+    and 1-million-row default limits in pnglibconf.dfa, that can be reset
+    by the user at build time or run time.  This provides a more robust
+    defense against DOS and as-yet undiscovered overflows.
+  Added PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED macro, on by default.
+  Allow user to call png_get_IHDR() with NULL arguments (Reuben Hawkins).
+  Rebuilt configure scripts with automake-1.15 and libtool-2.4.6
+  Moved png_set_filter() prototype into a PNG_WRITE_SUPPORTED block
+    of png.h.
+  Avoid runtime checks when converting integer to png_byte with
+    Visual Studio (Sergey Kosarevsky)
+  Removed some comments that the configure script did not handle
+    properly from scripts/pnglibconf.dfa and pnglibconf.h.prebuilt.
+  Free the unknown_chunks structure even when it contains no data.
+  Updated CMakeLists.txt to add OSX framework, change YES/NO to ON/OFF
+    for consistency, and remove some useless tests (Alexey Petruchik).
+  Remove pnglibconf.h, pnglibconf.c, pnglibconf.pre, pnglibconf.dfn,
+    and pnglibconf.out instead of pnglibconf.* in "make clean" (Cosmin).
+  Fixed simplified 8-bit-linear to sRGB alpha. The calculated alpha
+    value was wrong.  It's not clear if this affected the final stored
+    value; in the obvious code path the upper and lower 8-bits of the
+    alpha value were identical and the alpha was truncated to 8-bits
+    rather than dividing by 257 (John Bowler).
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/src/3rdparty/libpng/CHANGES b/src/3rdparty/libpng/CHANGES
index 70af827..1be09e9 100644
--- a/src/3rdparty/libpng/CHANGES
+++ b/src/3rdparty/libpng/CHANGES
@@ -1,4 +1,4 @@
-#if 0
+
 CHANGES - changes for libpng
 
 Version 0.2
@@ -2102,7 +2102,7 @@ Version 1.4.0beta24 [July 25, 2008]
     png_decompress_chunk(), and remove "chunkdata" from parameter list.
   Put a call to png_check_chunk_name() in png_read_chunk_header().
   Revised png_check_chunk_name() to reject a name with a lowercase 3rd byte.
-  Removed two calls to png_check_chunk_name() occuring later in the process.
+  Removed two calls to png_check_chunk_name() occurring later in the process.
   Define PNG_NO_ERROR_NUMBERS by default in pngconf.h
 
 Version 1.4.0beta25 [July 30, 2008]
@@ -3672,7 +3672,8 @@ Version 1.5.6 [November 3, 2011]
   No changes.
 
 Version 1.5.7beta01 [November 4, 2011]
-  Added support for ARM processor (Mans Rullgard)
+  Added support for ARM processor, when decoding all PNG up-filtered rows
+    and any other-filtered rows with 3 or 4 bytes per pixel (Mans Rullgard).
   Fixed bug in pngvalid on early allocation failure; fixed type cast in
     pngmem.c; pngvalid would attempt to call png_error() if the allocation
     of a png_struct or png_info failed. This would probably have led to a
@@ -3775,84 +3776,1434 @@ Version 1.5.7rc03 [December 7, 2011]
 Version 1.5.7 [December 15, 2011]
   Minor fixes to pngvalid.c for gcc 4.6.2 compatibility to remove warnings
     reported by earlier versions.
-
-Version 1.5.8beta01 [January 15, 2011]
-  Removed '#include config.h"' from contrib/libtests/pngvalid.c.  It's not
-    needed and causes trouble for VPATH building.
+  Fixed minor memset/sizeof errors in pngvalid.c.
+
+Version 1.6.0beta01 [December 15, 2011]
+  Removed machine-generated configure files from the GIT repository (they will
+    continue to appear in the tarball distributions and in the libpng15 and
+    earlier GIT branches).
+  Restored the new 'simplified' API, which was started in libpng-1.5.7beta02
+    but later deleted from libpng-1.5.7beta05.
+  Added example programs for the new 'simplified' API.
+  Added ANSI-C (C90) headers and require them, and take advantage of the
+    change. Also fixed some of the projects/* and contrib/* files that needed
+    updates for libpng16 and the move of pngvalid.c.
+    With this change the required ANSI-C header files are assumed to exist: the
+    implementation must provide float.h, limits.h, stdarg.h and stddef.h and
+    libpng relies on limits.h and stddef.h existing and behaving as defined
+    (the other two required headers aren't used).  Non-ANSI systems that don't
+    have stddef.h or limits.h will have to provide an appropriate fake
+    containing the relevant types and #defines.
+  The use of FAR/far has been eliminated and the definition of png_alloc_size_t
+    is now controlled by a flag so that 'small size_t' systems can select it
+    if necessary.  Libpng 1.6 may not currently work on such systems -- it
+    seems likely that it will ask 'malloc' for more than 65535 bytes with any
+    image that has a sufficiently large row size (rather than simply failing
+    to read such images).
+  New tools directory containing tools used to generate libpng code.
+  Fixed race conditions in parallel make builds. With higher degrees of
+    parallelism during 'make' the use of the same temporary file names such
+    as 'dfn*' can result in a race where a temporary file from one arm of the
+    build is deleted or overwritten in another arm.  This changes the
+    temporary files for suffix rules to always use $* and ensures that the
+    non-suffix rules use unique file names.
+
+Version 1.6.0beta02 [December 21, 2011]
+  Correct configure builds where build and source directories are separate.
+    The include path of 'config.h' was erroneously made relative in pngvalid.c
+    in libpng 1.5.7.
+
+Version 1.6.0beta03 [December 22, 2011]
+  Start-up code size improvements, error handler flexibility. These changes
+    alter how the tricky allocation of the initial png_struct and png_info
+    structures are handled. png_info is now handled in pretty much the same
+    way as everything else, except that the allocations handle NULL return
+    silently.  png_struct is changed in a similar way on allocation and on
+    deallocation a 'safety' error handler is put in place (which should never
+    be required).  The error handler itself is changed to permit mismatches
+    in the application and libpng error buffer size; however, this means a
+    silent change to the API to return the jmp_buf if the size doesn't match
+    the size from the libpng compilation; libpng now allocates the memory and
+    this may fail.  Overall these changes result in slight code size
+    reductions; however, this is a reduction in code that is always executed
+    so is particularly valuable.  Overall on a 64-bit system the libpng DLL
+    decreases in code size by 1733 bytes.  pngerror.o increases in size by
+    about 465 bytes because of the new functionality.
+  Added png_convert_to_rfc1123_buffer() and deprecated png_convert_to_rfc1123()
+    to avoid including a spurious buffer in the png_struct.
+
+Version 1.6.0beta04 [December 30, 2011]
+  Regenerated configure scripts with automake-1.11.2
+  Eliminated png_info_destroy(). It is now used only in png.c and only calls
+    one other internal function and memset().
+  Enabled png_get_sCAL_fixed() if floating point APIs are enabled. Previously
+    it was disabled whenever internal fixed point arithmetic was selected,
+    which meant it didn't exist even on systems where FP was available but not
+    preferred.
+  Added pngvalid.c compile time checks for const APIs.
+  Implemented 'restrict' for png_info and png_struct. Because of the way
+    libpng works both png_info and png_struct are always accessed via a
+    single pointer.  This means adding C99 'restrict' to the pointer gives
+    the compiler some opportunity to optimize the code.  This change allows
+    that.
   Moved AC_MSG_CHECKING([if libraries can be versioned]) later to the proper
     location in configure.ac (Gilles Espinasse).
+  Changed png_memcpy to C assignment where appropriate. Changed all those
+    uses of png_memcpy that were doing a simple assignment to assignments
+    (all those cases where the thing being copied is a non-array C L-value).
+  Added some error checking to png_set_*() routines.
+  Removed the reference to the non-exported function png_memcpy() from
+    example.c.
+  Fixed the Visual C 64-bit build - it requires jmp_buf to be aligned, but
+    it had become misaligned.
+  Revised contrib/pngminus/pnm2png.c to avoid warnings when png_uint_32
+    and unsigned long are of different sizes.
+
+Version 1.6.0beta05 [January 15, 2012]
+  Updated manual with description of the simplified API (copied from png.h)
   Fix bug in pngerror.c: some long warnings were being improperly truncated
     (CVE-2011-3464, bug introduced in libpng-1.5.3beta05).
 
-Version 1.5.8rc01 [January 21, 2012]
-  No changes.
-
-Version 1.5.8rc02 [January 25, 2012]
+Version 1.6.0beta06 [January 24, 2012]
+  Added palette support to the simplified APIs. This commit
+    changes some of the macro definitions in png.h, app code
+    may need corresponding changes.
+  Increased the formatted warning buffer to 192 bytes.
+  Added color-map support to simplified API. This is an initial version for
+    review; the documentation has not yet been updated.
   Fixed Min/GW uninstall to remove libpng.dll.a
-  Conditionalize the install rules for MINGW and CYGWIN in CMakeLists.txt
-
-Version 1.5.8 [February 1, 2012]
-  No changes.
-
-Version 1.5.9beta01 [February 3, 2012]
-  Rebuilt configure scripts in the tar distributions.
 
-Version 1.5.9beta02 [February 16, 2012]
-  Removed two unused definitions from scripts/pnglibconf.h.prebuilt
+Version 1.6.0beta07 [January 28, 2012]
+  Eliminated Intel icc/icl compiler warnings. The Intel (GCC derived)
+    compiler issues slightly different warnings from those issued by the
+    current vesions of GCC. This eliminates those warnings by
+    adding/removing casts and small code rewrites.
+  Updated configure.ac from autoupdate: added --enable-werror option.
+    Also some layout regularization and removal of introduced tab characters
+    (replaced with 3-character indentation).  Obsolete macros identified by
+    autoupdate have been removed; the replacements are all in 2.59 so
+    the pre-req hasn't been changed.  --enable-werror checks for support
+    for -Werror (or the given argument) in the compiler.  This mimics the
+    gcc configure option by allowing -Werror to be turned on safely; without
+    the option the tests written in configure itself fail compilation because
+    they cause compiler warnings.
+  Rewrote autogen.sh to run autoreconf instead of running tools one-by-one.
+  Conditionalize the install rules for MINGW and CYGWIN in CMakeLists.txt and
+    set CMAKE_LIBRARY_OUTPUT_DIRECTORY to "lib" on all platforms (C. Yapp).
+  Freeze libtool files in the 'scripts' directory. This version of autogen.sh
+    attempts to dissuade people from running it when it is not, or should not,
+    be necessary.  In fact, autogen.sh does not work when run in a libpng
+    directory extracted from a tar distribution anymore. You must run it in
+    a GIT clone instead.
+  Added two images to contrib/pngsuite (1-bit and 2-bit transparent grayscale),
+    and renamed three whose names were inconsistent with those in
+    pngsuite/README.txt.
+
+Version 1.6.0beta08 [February 1, 2012]
+  Fixed Image::colormap misalignment in pngstest.c
+  Check libtool/libtoolize version number (2.4.2) in configure.ac
+  Divide test-pngstest.sh into separate pngstest runs for basic and
+    transparent images.
+  Moved automake options to AM_INIT_AUTOMAKE in configure.ac
+  Added color-tests, silent-rules (Not yet implemented in Makefile.am) and
+    version checking to configure.ac
+  Improved pngstest speed by not doing redundant tests and add const to
+    the background parameter of png_image_finish_read. The --background
+    option is now done automagically only when required, so that commandline
+    option no longer exists.
+  Cleaned up pngpriv.h to consistently declare all functions and data.
+    Also eliminated PNG_CONST_DATA, which is apparently not needed but we
+    can't be sure until it is gone.
+  Added symbol prefixing that allows all the libpng external symbols
+    to be prefixed (suggested by Reuben Hawkins).
+  Updated "ftbb*.png" list in the owatcom and vstudio projects.
+  Fixed 'prefix' builds on clean systems. The generation of pngprefix.h
+    should not require itself.
+  Updated INSTALL to explain that autogen.sh must be run in a GIT clone,
+    not in a libpng directory extracted from a tar distribution.
+
+Version 1.6.0beta09 [February 1, 2012]
+  Reverted the prebuilt configure files to libpng-1.6.0beta05 condition.
+
+Version 1.6.0beta10 [February 3, 2012]
+  Added Z_SOLO for zlib-1.2.6+ and correct pngstest tests
+  Updated list of test images in CMakeLists.txt
+  Updated the prebuilt configure files to current condition.
+  Revised INSTALL information about autogen.sh; it works in tar distributions.
+
+Version 1.6.0beta11 [February 16, 2012]
+  Fix character count in pngstest command in projects/owatcom/pngstest.tgt
+  Revised test-pngstest.sh to report PASS/FAIL for each image.
+  Updated documentation about the simplified API.
+  Corrected estimate of error in libpng png_set_rgb_to_gray API.  The API is
+    extremely inaccurate for sRGB conversions because it uses an 8-bit
+    intermediate linear value and it does not use the sRGB transform, so it
+    suffers from the known instability in gamma transforms for values close
+    to 0 (see Poynton).  The net result is that the calculation has a maximum
+    error of 14.99/255; 0.5/255^(1/2.2).  pngstest now uses 15 for the
+    permitted 8-bit error. This may still not be enough because of arithmetic
+    error.
   Removed some unused arrays (with #ifdef) from png_read_push_finish_row().
+  Fixed a memory overwrite bug in simplified read of RGB PNG with
+    non-linear gamma Also bugs in the error checking in pngread.c and changed
+    quite a lot of the checks in pngstest.c to be correct; either correctly
+    written or not over-optimistic.  The pngstest changes are insufficient to
+    allow all possible RGB transforms to be passed; pngstest cmppixel needs
+    to be rewritten to make it clearer which errors it allows and then changed
+    to permit known inaccuracies.
   Removed tests for no-longer-used *_EMPTY_PLTE_SUPPORTED from pngstruct.h
-
-Version 1.5.9rc01 [February 17, 2012]
+  Fixed fixed/float API export conditionals. 1) If FIXED_POINT or
+    FLOATING_POINT options were switched off, png.h ended up with lone ';'
+    characters.  This is not valid ANSI-C outside a function.  The ';'
+    characters have been moved inside the definition of PNG_FP_EXPORT and
+    PNG_FIXED_EXPORT. 2) If either option was switched off, the declaration
+    of the corresponding functions were completely omitted, even though some
+    of them are still used internally.  The result is still valid, but
+    produces warnings from gcc with some warning options (including -Wall). The
+    fix is to cause png.h to declare the functions with PNG_INTERNAL_FUNCTION
+    when png.h is included from pngpriv.h.
+  Check for invalid palette index while reading paletted PNG.  When one is
+    found, issue a warning and increase png_ptr->num_palette accordingly.
+    Apps are responsible for checking to see if that happened.
+
+Version 1.6.0beta12 [February 18, 2012]
+  Do not increase num_palette on invalid_index.
+  Relocated check for invalid palette index to pngrtran.c, after unpacking
+    the sub-8-bit pixels.
   Fixed CVE-2011-3026 buffer overrun bug.  This bug was introduced when
     iCCP chunk support was added at libpng-1.0.6. Deal more correctly with the
     test on iCCP chunk length. Also removed spurious casts that may hide
     problems on 16-bit systems.
 
-Version 1.5.9 [February 18, 2012]
-  No changes.
-
-Version 1.5.10beta01 [February 24, 2012]
-  Removed two useless #ifdef directives from pngread.c and one from pngrutil.c
-  Always put the CMAKE_LIBRARY in "lib" (removed special WIN32 case).
-  Removed empty vstudio/pngstest directory (Clifford Yapp).
+Version 1.6.0beta13 [February 24, 2012]
   Eliminated redundant png_push_read_tEXt|zTXt|iTXt|unknown code from
     pngpread.c and use the sequential png_handle_tEXt, etc., in pngrutil.c;
     now that png_ptr->buffer is inaccessible to applications, the special
     handling is no longer useful.
-  Fixed bug with png_handle_hIST with odd chunk length (Frank Busse).
-  Added PNG_SAFE_LIMITS feature to pnglibconf.dfa and code in pngconf.h
-    to reset the user limits to safe ones if PNG_SAFE_LIMITS is defined.
-    To enable, use "CPPFLAGS=-DPNG_SAFE_LIMITS_SUPPORTED" on the configure
-    command or put "#define PNG_SAFE_LIMITS_SUPPORTED" in pnglibconf.h.
-  Revised the SAFE_LIMITS feature to be the same as the feature in libpng16.
-  Added information about the new limits in the manual.
+  Added PNG_SAFE_LIMITS feature to pnglibconf.dfa, pngpriv.h, and new
+    pngusr.dfa to reset the user limits to safe ones if PNG_SAFE_LIMITS is
+    defined.  To enable, use "CPPFLAGS=-DPNG_SAFE_LIMITS_SUPPORTED=1" on the
+    configure command or put #define PNG_SAFE_LIMITS_SUPPORTED in
+    pnglibconf.h.prebuilt and pnglibconf.h.
 
-Version 1.5.10beta02 [February 27, 2012]
+Version 1.6.0beta14 [February 27, 2012]
+  Added information about the new limits in the manual.
   Updated Makefile.in
 
-Version 1.5.10beta03 [March 6, 2012]
+Version 1.6.0beta15 [March 2, 2012]
   Removed unused "current_text" members of png_struct and the png_free()
     of png_ptr->current_text from pngread.c
-  Added palette-index checking. Issue a png_warning() if an invalid index is
-    found.
-
-Version 1.5.10beta04 [March 10, 2012]
-  Fixed PNG_LIBPNG_BUILD_BASE_TYPE definition.
-  Fixed CMF optimization of non-IDAT compressed chunks, which was added at
-    libpng-1.5.4.  It sometimes produced too small of a window.
-
-Version 1.5.10beta05 [March 10, 2012]
+  Rewrote pngstest.c for substantial speed improvement.
+  Fixed transparent pixel and 16-bit rgb tests in pngstest and removed a
+    spurious check in pngwrite.c
+  Added PNG_IMAGE_FLAG_FAST for the benefit of applications that store
+    intermediate files, or intermediate in-memory data, while processing
+    image data with the simplified API.  The option makes the files larger
+    but faster to write and read.  pngstest now uses this by default; this
+    can be disabled with the --slow option.
+  Improved pngstest fine tuning of error numbers, new test file generator.
+    The generator generates images that test the full range of sample values,
+    allow the error numbers in pngstest to be tuned and checked.  makepng
+    also allows generation of images with extra chunks, although this is
+    still work-in-progress.
+  Added check for invalid palette index while reading.
+  Fixed some bugs in ICC profile writing. The code should now accept
+    all potentially valid ICC profiles and reject obviously invalid ones.
+    It now uses png_error() to do so rather than casually writing a PNG
+    without the necessary color data.
+  Removed whitespace from the end of lines in all source files and scripts.
+
+Version 1.6.0beta16 [March 6, 2012]
+  Relocated palette-index checking function from pngrutil.c to pngtrans.c
+  Added palette-index checking while writing.
+  Changed png_inflate() and calling routines to avoid overflow problems.
+    This is an intermediate check-in that solves the immediate problems and
+    introduces one performance improvement (avoiding a copy via png_ptr->zbuf.)
+    Further changes will be made to make ICC profile handling more secure.
+  Fixed build warnings (MSVC, GCC, GCC v3). Cygwin GCC with default options
+    declares 'index' as a global, causing a warning if it is used as a local
+    variable.  GCC 64-bit warns about assigning a (size_t) (unsigned 64-bit)
+    to an (int) (signed 32-bit).  MSVC, however, warns about using the
+    unary '-' operator on an unsigned value (even though it is well defined
+    by ANSI-C to be ~x+1).  The padding calculation was changed to use a
+    different method.  Removed the tests on png_ptr->pass.
+  Added contrib/libtests/tarith.c to test internal arithmetic functions from
+    png.c. This is a libpng maintainer program used to validate changes to the
+    internal arithmetic functions.
+  Made read 'inflate' handling like write 'deflate' handling. The read
+    code now claims and releases png_ptr->zstream, like the write code.
+    The bug whereby the progressive reader failed to release the zstream
+    is now fixed, all initialization is delayed, and the code checks for
+    changed parameters on deflate rather than always calling
+    deflatedEnd/deflateInit.
+  Validate the zTXt strings in pngvalid.
+  Added code to validate the windowBits value passed to deflateInit2().
+    If the call to deflateInit2() is wrong a png_warning will be issued
+    (in fact this is harmless, but the PNG data produced may be sub-optimal).
+
+Version 1.6.0beta17 [March 10, 2012]
+  Fixed PNG_LIBPNG_BUILD_BASE_TYPE definition. 
   Reject all iCCP chunks after the first, even if the first one is invalid.
+  Deflate/inflate was reworked to move common zlib calls into single
+    functions [rw]util.c.  A new shared keyword check routine was also added
+    and the 'zbuf' is no longer allocated on progressive read.  It is now
+    possible to call png_inflate() incrementally.  A warning is no longer
+    issued if the language tag or translated keyword in the iTXt chunk
+    has zero length.
+  If benign errors are disabled use maximum window on ancilliary inflate.
+    This works round a bug introduced in 1.5.4 where compressed ancillary
+    chunks could end up with a too-small windowBits value in the deflate
+    header.
+
+Version 1.6.0beta18 [March 16, 2012]
   Issue a png_benign_error() instead of png_warning() about bad palette index.
+  In pngtest, treat benign errors as errors if "-strict" is present.
   Fixed an off-by-one error in the palette index checking function.
+  Fixed a compiler warning under Cygwin (Windows-7, 32-bit system)
   Revised example.c to put text strings in a temporary character array
     instead of directly assigning string constants to png_textp members.
     This avoids compiler warnings when -Wwrite-strings is enabled.
-
-Version 1.5.10 [March 29, 2012]
+  Added output flushing to aid debugging under Visual Studio. Unfortunately
+    this is necessary because the VS2010 output window otherwise simply loses
+    the error messages on error (they weren't flushed to the window before
+    the process exited, apparently!)
+  Added configuration support for benign errors and changed the read
+    default. Also changed some warnings in the iCCP and sRGB handling
+    from to benign errors. Configuration now makes read benign
+    errors warnings and write benign errors to errors by default (thus
+    changing the behavior on read).  The simplified API always forces
+    read benign errors to warnings (regardless of the system default, unless
+    this is disabled in which case the simplified API can't be built.)
+
+Version 1.6.0beta19 [March 18, 2012]
+  Work around for duplicate row start calls; added warning messages.
+    This turns on PNG_FLAG_DETECT_UNINITIALIZED to detect app code that
+    fails to call one of the 'start' routines (not enabled in libpng-1.5
+    because it is technically an API change, since it did normally work
+    before.)  It also makes duplicate calls to png_read_start_row (an
+    internal function called at the start of the image read) benign, as
+    they were before changes to use png_inflate_claim. Somehow webkit is
+    causing this to happen; this is probably a mis-feature in the zlib
+    changes so this commit is only a work-round.
+  Removed erroneous setting of DETECT_UNINITIALIZED and added more
+    checks. The code now does a png_error if an attempt is made to do the
+    row initialization twice; this is an application error and it has
+    serious consequences because the transform data in png_struct is
+    changed by each call.
+  Added application error reporting and added chunk names to read
+    benign errors; also added --strict to pngstest - not enabled
+    yet because a warning is produced.
+  Avoid the double gamma correction warning in the simplified API.
+    This allows the --strict option to pass in the pngstest checks
+
+Version 1.6.0beta20 [March 29, 2012]
+  Changed chunk handler warnings into benign errors, incrementally load iCCP
+  Added checksum-icc.c to contrib/tools
   Prevent PNG_EXPAND+PNG_SHIFT doing the shift twice.
+  Recognize known sRGB ICC profiles while reading; prefer writing the
+    iCCP profile over writing the sRGB chunk, controlled by the
+    PNG_sRGB_PROFILE_CHECKS option.
   Revised png_set_text_2() to avoid potential memory corruption (fixes
-    CVE-2011-3048).
+    CVE-2011-3048, also known as CVE-2012-3425).
+
+Version 1.6.0beta21 [April 27, 2012]
+  Revised scripts/makefile.darwin: use system zlib; remove quotes around
+    architecture list; add missing ppc architecture; add architecture options
+    to shared library link; don't try to create a shared lib based on missing
+    RELEASE variable.
+  Enable png_set_check_for_invalid_index() for both read and write.
+  Removed #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED in pngpriv.h around
+    declaration of png_handle_unknown().
+  Added -lssp_nonshared in a comment in scripts/makefile.freebsd
+    and changed deprecated NOOBJ and NOPROFILE to NO_OBJ and NO_PROFILE.
+
+Version 1.6.0beta22 [May 23, 2012]
+  Removed need for -Wno-cast-align with clang.  clang correctly warns on
+    alignment increasing pointer casts when -Wcast-align is passed. This
+    fixes the cases that clang warns about either by eliminating the
+    casts from png_bytep to png_uint_16p (pngread.c), or, for pngrutil.c
+    where the cast is previously verified or pngstest.c where it is OK, by
+    introducing new png_aligncast macros to do the cast in a way that clang
+    accepts.
+
+Version 1.6.0beta23 [June 6, 2012]
+  Revised CMakeLists.txt to not attempt to make a symlink under mingw.
+  Made fixes for new optimization warnings from gcc 4.7.0. The compiler
+    performs an optimization which is safe; however it then warns about it.
+    Changing the type of 'palette_number' in pngvalid.c removes the warning.
+  Do not depend upon a GCC feature macro being available for use in generating
+    the linker mapfile symbol prefix.
+  Improved performance of new do_check_palette_indexes() function (only
+    update the value when it actually increases, move test for whether
+    the check is wanted out of the function.
+
+Version 1.6.0beta24 [June 7, 2012]
+  Don't check palette indexes if num_palette is 0 (as it can be in MNG files).
+
+Version 1.6.0beta25 [June 16, 2012]
+  Revised png_set_keep_unknown_chunks() so num_chunks < 0 means ignore all
+    unknown chunks and all known chunks except for IHDR, PLTE, tRNS, IDAT,
+    and IEND.  Previously it only meant ignore all unknown chunks, the
+    same as num_chunks == 0. Revised png_image_skip_unused_chunks() to
+    provide a list of chunks to be processed instead of a list of chunks to
+    ignore.  Revised contrib/gregbook/readpng2.c accordingly.
+
+Version 1.6.0beta26 [July 10, 2012]
+  Removed scripts/makefile.cegcc from the *.zip and *.7z distributions; it
+    depends on configure, which is not included in those archives.
+  Moved scripts/chkfmt to contrib/tools.
+  Changed "a+w" to "u+w" in Makefile.in to fix CVE-2012-3386.
+
+Version 1.6.0beta27 [August 11, 2012]
+  Do not compile PNG_DEPRECATED, PNG_ALLOC and PNG_PRIVATE when __GNUC__ < 3.
+  Do not use __restrict when GNUC is <= 3.1
+  Removed references to png_zalloc() and png_zfree() from the manual.
+  Fixed configurations where floating point is completely disabled.  Because
+    of the changes to support symbol prefixing PNG_INTERNAL_FUNCTION declares
+    floating point APIs during libpng builds even if they are completely
+    disabled. This requires the png floating point types (png_double*) to be
+    declared even though the functions are never actually defined.  This
+    change provides a dummy definition so that the declarations work, yet any
+    implementation will fail to compile because of an incomplete type.
+  Re-eliminated the use of strcpy() in pngtest.c.  An unncessary use of
+    strcpy() was accidentally re-introduced in libpng16; this change replaces
+    it with strncpy().
+  Eliminated use of png_sizeof(); use sizeof() instead.
+  Use a consistent style for (sizeof type) and (sizeof (array))
+  Cleanup of png_set_filler().  This function does very different things on
+    read and write.  In libpng 1.6 the two cases can be distinguished and
+    considerable code cleanup, and extra error checking, is possible.  This
+    makes calls on the write side that have no effect be ignored with a
+    png_app_error(), which can be disabled in the app using
+    png_set_benign_errors(), and removes the spurious use of usr_channels
+    on the read side.
+  Insist on autotools 1.12.1 for git builds because there are security issues
+    with 1.12 and insisting on anything less would allow 1.12 to be used.
+  Removed info_ptr->signature[8] from WRITE-only builds.
+  Add some conditions for compiling png_fixed().  This is a small function
+    but it requires "-lm" on some platforms.
+  Cause pngtest --strict to fail on any warning from libpng (not just errors)
+    and cause it not to fail at the comparison step if libpng lacks support
+    for writing chunks that it reads from the input (currently only implemented
+    for compressed text chunks).
+  Make all three "make check" test programs work without READ or WRITE support.
+    Now "make check" will succeed even if libpng is compiled with -DPNG_NO_READ
+    or -DPNG_NO_WRITE.  The tests performed are reduced, but the basic reading
+    and writing of a PNG file is always tested by one or more of the tests.
+  Consistently use strlen(), memset(), memcpy(), and memcmp() instead of the
+    png_strlen(), png_memset(), png_memcpy(), and png_memcmp() macros.
+  Removed the png_sizeof(), png_strlen(), png_memset(), png_memcpy(), and
+    png_memcmp() macros.
+  Work around gcc 3.x and Microsoft Visual Studio 2010 complaints. Both object
+    to the split initialization of num_chunks.
+
+Version 1.6.0beta28 [August 29, 2012]
+  Unknown handling fixes and clean up. This adds more correct option
+    control of the unknown handling, corrects the pre-existing bug where
+    the per-chunk 'keep' setting is ignored and makes it possible to skip
+    IDAT chunks in the sequential reader (broken in earlier 1.6 versions).
+    There is a new test program, test-unknown.c, which is a work in progress
+    (not currently part of the test suite).  Comments in the header files now
+    explain how the unknown handling works.
+  Allow fine grain control of unknown chunk APIs. This change allows
+    png_set_keep_unknown_chunks() to be turned off if not required and causes
+    both read and write to behave appropriately (on read this is only possible
+    if the user callback is used to handle unknown chunks).  The change
+    also removes the support for storing unknown chunks in the info_struct
+    if the only unknown handling enabled is via the callback, allowing libpng
+    to be configured with callback reading and none of the unnecessary code.
+  Corrected fix for unknown handling in pngtest. This reinstates the
+    libpng handling of unknown chunks other than vpAg and sTER (including
+    unsafe-to-copy chunks which were dropped before) and eliminates the
+    repositioning of vpAg and sTER in pngtest.png by changing pngtest.png
+    (so the chunks are where libpng would put them).
+  Added "tunknown" test and corrected a logic error in png_handle_unknown()
+    when SAVE support is absent.  Moved the shell test scripts for
+    contrib/libtests from the libpng top directory to contrib/libtests.
+    png_handle_unknown() must always read or skip the chunk, if
+    SAVE_UNKNOWN_CHUNKS is turned off *and* the application does not set
+    a user callback an unknown chunk will not be read, leading to a read
+    error, which was revealed by the "tunknown" test.
+  Cleaned up and corrected ICC profile handling.
+    contrib/libtests/makepng: corrected 'rgb' and 'gray' cases.  profile_error
+    messages could be truncated; made a correct buffer size calculation and
+    adjusted pngerror.c appropriately. png_icc_check_* checking improved;
+    changed the functions to receive the correct color type of the PNG on read
+    or write and check that it matches the color space of the profile (despite
+    what the comments said before, there is danger in assuming the app will
+    cope correctly with an RGB profile on a grayscale image and, since it
+    violates the PNG spec, allowing it is certain to produce inconsistent
+    app behavior and might even cause app crashes.) Check that profiles
+    contain the tags needed to process the PNG (tags all required by the ICC
+    spec). Removed unused PNG_STATIC from pngpriv.h.
+
+Version 1.6.0beta29 [September 4, 2012]
+  Fixed the simplified API example programs to add the *colormap parameter
+    to several of he API and improved the error message if the version field
+    is not set.
+  Added contrib/examples/* to the *.zip and *.7z distributions.
+  Updated simplified API synopses and description of the png_image structure
+    in the manual.
+  Made makepng and pngtest produce identical PNGs, add "--relaxed" option
+    to pngtest. The "--relaxed" option turns off the benign errors that are
+    enabled by default in pre-RC builds. makepng can now write ICC profiles
+    where the length has not been extended to a multiple of 4, and pngtest
+    now intercepts all libpng errors, allowing the previously-introduced
+    "--strict test" on no warnings to actually work.
+  Improved ICC profile handling including cHRM chunk generation and fixed
+    Cygwin+MSVC build errors. The ICC profile handling now includes more
+    checking.  Several errors that caused rejection of the profile are now
+    handled with a warning in such a way that the invalid profiles will be
+    read by default in release (but not pre-RC) builds but will not be
+    written by default.  The easy part of handling the cHRM chunk is written,
+    where the ICC profile contains the required data.  The more difficult
+    part plus guessing a gAMA value requires code to pass selected RGB values
+    through the profile.
+
+Version 1.6.0beta30 [October 24, 2012]
+  Changed ICC profile matrix/vector types to not depend on array type rules.
+    By the ANSI-C standard the new types should be identical to the previous
+    versions, and all known versions of gcc tested with the previous versions
+    except for GCC-4.2.1 work with this version.  The change makes the ANSI-C
+    rule that const applied to an array of elements applies instead to the
+    elements in the array moot by explicitly applying const to the base
+    elements of the png_icc_matrix and png_icc_vector types. The accidental
+    (harmless) 'const' previously applied to the parameters of two of the
+    functions have also been removed.
+  Added a work around for GCC 4.2 optimization bug.
+  Marked the broken (bad white point) original HP sRGB profiles correctly and
+    correct comments.
+  Added -DZ_SOLO to contrib/pngminim/*/makefile to work with zlib-1.2.7
+  Use /MDd for vstudio debug builds. Also added pngunkown to the vstudio
+    builds, fixed build errors and corrected a minor exit code error in
+    pngvalid if the 'touch' file name is invalid.
+  Add updated WARNING file to projects/vstudio from libpng 1.5/vstudio
+  Fixed build when using #define PNG_NO_READ_GAMMA in png_do_compose() in
+    pngrtran.c (Domani Hannes).
+
+Version 1.6.0beta31 [November 1, 2012]
+  Undid the erroneous change to vstudio/pngvalid build in libpng-1.6.0beta30.
+  Made pngvalid so that it will build outside the libpng source tree.
+  Made builds -DPNG_NO_READ_GAMMA compile (the unit tests still fail).
+  Made PNG_NO_READ_GAMMA switch off interfaces that depend on READ_GAMMA.
+    Prior to 1.6.0 switching off READ_GAMMA did unpredictable things to the
+    interfaces that use it (specifically, png_do_background in 1.4 would
+    simply display composite for grayscale images but do composition
+    with the incorrect arithmetic for color ones). In 1.6 the semantic
+    of -DPNG_NO_READ_GAMMA is changed to simply disable any interface that
+    depends on it; this obliges people who set it to consider whether they
+    really want it off if they happen to use any of the interfaces in
+    question (typically most users who disable it won't).
+  Fixed GUIDs in projects/vstudio. Some were duplicated or missing,
+    resulting in VS2010 having to update the files.
+  Removed non-working ICC profile support code that was mostly added to
+    libpng-1.6.0beta29 and beta30. There was too much code for too little
+    gain; implementing full ICC color correction may be desireable but is left
+    up to applications.
+
+Version 1.6.0beta32 [November 25, 2012]
+  Fixed an intermittent SEGV in pngstest due to an uninitialized array element.
+  Added the ability for contrib/libtests/makepng.c to make a PNG with just one
+    color. This is useful for debugging pngstest color inaccuracy reports.
+  Fixed error checking in the simplified write API (Olaf van der Spek)
+  Made png_user_version_check() ok to use with libpng version 1.10.x and later.
+
+Version 1.6.0beta33 [December 15, 2012]
+  Fixed typo in png.c (PNG_SET_CHUNK_MALLOC_MAX should be PNG_CHUNK_MALLOC_MAX)
+    that causes the MALLOC_MAX limit not to work (John Bowler)
+  Change png_warning() to png_app_error() in pngwrite.c and comment the
+    fall-through condition.
+  Change png_warning() to png_app_warning() in png_write_tRNS().
+  Rearranged the ARM-NEON optimizations: Isolated the machine specific code
+    to the hardware subdirectory and added comments to pngrutil.c so that
+    implementors of other optimizations know what to do.
+  Fixed cases of unquoted DESTDIR in Makefile.am
+  Rebuilt Makefile.in, etc., with autoconf-2.69 and automake-1.12.5.
+
+Version 1.6.0beta34 [December 19, 2012]
+  Cleaned up whitespace in the synopsis portion of the manpage "libpng.3"
+  Disassembled the version number in scripts/options.awk (necessary for
+    building on SunOs).
+
+Version 1.6.0beta35 [December 23, 2012]
+  Made default Zlib compression settings be configurable. This adds #defines to
+    pnglibconf.h to control the defaults.
+  Fixed Windows build issues, enabled ARM compilation. Various warnings issued
+    by earlier versions of GCC fixed for Cygwin and Min/GW (which both use old
+    GCCs.) ARM support is enabled by default in zlib.props (unsupported by
+    Microsoft) and ARM compilation is made possible by deleting the check for
+    x86. The test programs cannot be run because they are not signed.
+
+Version 1.6.0beta36 [January 2, 2013]
+  Discontinued distributing libpng-1.x.x.tar.bz2.
+  Discontinued distributing libpng-1.7.0-1.6.0-diff.txt and similar.
+  Rebuilt configure with autoconf-2.69 (inadvertently not done in beta33)
+  Fixed 'make distcheck' on SUN OS - libpng.so was not being removed
+
+Version 1.6.0beta37 [January 10, 2013]
+  Fixed conceivable but difficult to repro overflow. Also added two test
+    programs to generate and test a PNG which should have the problem.
+
+Version 1.6.0beta39 [January 19, 2013]
+  Again corrected attempt at overflow detection in png_set_unknown_chunks()
+  (CVE-2013-7353).  Added overflow detection in png_set_sPLT() and
+  png_set_text_2() (CVE-2013-7354).
+
+Version 1.6.0beta40 [January 20, 2013]
+  Use consistent handling of overflows in text, sPLT and unknown png_set_* APIs
+
+Version 1.6.0rc01 [January 26, 2013]
+  No changes.
+
+Version 1.6.0rc02 [February 4, 2013]
+  Added png_get_palette_max() function.
+
+Version 1.6.0rc03 [February 5, 2013]
+  Fixed the png_get_palette_max API.
+
+Version 1.6.0rc04 [February 7, 2013]
+  Turn serial tests back on (recently turned off by autotools upgrade).
+
+Version 1.6.0rc05 [February 8, 2013]
+  Update manual about png_get_palette_max().
+
+Version 1.6.0rc06 [February 9, 2013]
+  Fixed missing dependency in --prefix builds The intermediate
+    internal 'prefix.h' file can only be generated correctly after
+    pnglibconf.h, however the dependency was not in Makefile.am.  The
+    symptoms are unpredictable depending on the order make chooses to
+    build pngprefix.h and pnglibconf.h, often the error goes unnoticed
+    because there is a system pnglibconf.h to use instead.
+
+Version 1.6.0rc07 [February 10, 2013]
+  Enclosed the new png_get_palette_max in #ifdef PNG_GET_PALETTE_MAX_SUPPORTED
+    block, and revised pnglibconf.h and pnglibconf.h.prebuilt accordingly.
+
+Version 1.6.0rc08 [February 10, 2013]
+  Fix typo in png.h #ifdef
+
+Version 1.6.0 [February 14, 2013]
+  No changes.
+
+Version 1.6.1beta01 [February 16, 2013]
+  Made symbol prefixing work with the ARM neon optimizations. Also allow
+    pngpriv.h to be included for preprocessor definitions only, so it can
+    be used in non-C/C++ files. Back ported from libpng 1.7.
+  Made sRGB check numbers consistent.
+  Ported libpng 1.5 options.awk/dfn file handling to 1.6, fixed one bug.
+  Removed cc -E workround, corrected png_get_palette_max API Tested on
+    SUN OS cc 5.9, which demonstrates the tokenization problem previously
+    avoided by using /lib/cpp.  Since all .dfn output is now protected in
+    double quotes unless it is to be macro substituted the fix should
+    work everywhere.
+  Enabled parallel tests - back ported from libpng-1.7.
+  scripts/pnglibconf.dfa formatting improvements back ported from libpng17.
+  Fixed a race condition in the creation of the build 'scripts' directory
+    while building with a parallel make.
+  Use approved/supported Android method to check for NEON, use Linux/POSIX
+    1003.1 API to check /proc/self/auxv avoiding buffer allocation and other
+    library calls (ported from libpng15).
+
+Version 1.6.1beta02 [February 19, 2013]
+  Use parentheses more consistently in "#if defined(MACRO)" tests.
+  Folded long lines.
+  Reenabled code to allow zero length PLTE chunks for MNG.
+
+Version 1.6.1beta03 [February 22, 2013]
+  Fixed ALIGNED_MEMORY support.
+  Allow run-time ARM NEON checking to be disabled. A new configure option:
+    --enable-arm-neon=always will stop the run-time checks. New checks
+    within arm/arm_init.c will cause the code not to be compiled unless
+    __ARM_NEON__ is set. This should make it fail safe (if someone asks
+    for it on then the build will fail if it can't be done.)
+  Updated the INSTALL document.
+
+Version 1.6.1beta04 [February 27, 2013]
+  Revised INSTALL to recommend using CPPFLAGS instead of INCLUDES.
+  Revised scripts/makefile.freebsd to respect ZLIBLIB and ZLIBINC.
+  Revised scripts/dfn.awk to work with the buggy MSYS awk that has trouble
+    with CRLF line endings.
+
+Version 1.6.1beta05 [March 1, 2013]
+  Avoid a possible memory leak in contrib/gregbook/readpng.c
+
+Version 1.6.1beta06 [March 4, 2013]
+  Better documentation of unknown handling API interactions.
+  Corrected Android builds and corrected libpng.vers with symbol
+    prefixing. This adds an API to set optimization options externally,
+    providing an alternative and general solution for the non-portable
+    run-time tests used by the ARM Neon code.  It also makes those tests
+    compile and link on Android.
+  The order of settings vs options in pnglibconf.h is reversed to allow
+    settings to depend on options and options can now set (or override) the
+    defaults for settings.
+
+Version 1.6.1beta07 [March 7, 2013]
+  Corrected simplified API default gamma for color-mapped output, added
+    a flag to change default. In 1.6.0 when the simplified API was used
+    to produce color-mapped output from an input image with no gamma
+    information the gamma assumed for the input could be different from
+    that assumed for non-color-mapped output.  In particular 16-bit depth
+    input files were assumed to be sRGB encoded, whereas in the 'direct'
+    case they were assumed to have linear data.  This was an error.  The
+    fix makes the simplified API treat all input files the same way and
+    adds a new flag to the png_image::flags member to allow the
+    application/user to specify that 16-bit files contain sRGB data
+    rather than the default linear.
+  Fixed bugs in the pngpixel and makepng test programs.
+
+Version 1.6.1beta08 [March 7, 2013]
+  Fixed CMakelists.txt to allow building a single variant of the library
+    (Claudio Bley):
+  Introduced a PNG_LIB_TARGETS variable that lists all activated library
+    targets.  It is an error if this variable ends up empty, ie. you have
+    to build at least one library variant.
+  Made the *_COPY targets only depend on library targets actually being build.
+  Use PNG_LIB_TARGETS to unify a code path.
+  Changed the CREATE_SYMLINK macro to expect the full path to a file as the
+    first argument. When symlinking the filename component of that path is
+    determined and used as the link target.
+  Use copy_if_different in the CREATE_SYMLINK macro.
+
+Version 1.6.1beta09 [March 13, 2013]
+  Eliminated two warnings from the Intel C compiler. The warnings are
+    technically valid, although a reasonable treatment of division would
+    show it to be incorrect.
+
+Version 1.6.1rc01 [March 21, 2013]
+  No changes.
+
+Version 1.6.1 [March 28, 2013]
+  No changes.
+
+Version 1.6.2beta01 [April 14, 2013]
+  Updated documentation of 1.5.x to 1.6.x changes in iCCP chunk handling.
+  Fixed incorrect warning of excess deflate data. End condition - the
+    warning would be produced if the end of the deflate stream wasn't read
+    in the last row.  The warning is harmless.
+  Corrected the test on user transform changes on read. It was in the
+    png_set of the transform function, but that doesn't matter unless the
+    transform function changes the rowbuf size, and that is only valid if
+    transform_info is called.
+  Corrected a misplaced closing bracket in contrib/libtests/pngvalid.c
+    (Flavio Medeiros).
+  Corrected length written to uncompressed iTXt chunks (Samuli Suominen).
+    Bug was introduced in libpng-1.6.0.
+
+Version 1.6.2rc01 [April 18, 2013]
+  Added contrib/tools/fixitxt.c, to repair the erroneous iTXt chunk length
+    written by libpng-1.6.0 and 1.6.1.
+  Disallow storing sRGB information when the sRGB is not supported.
+
+Version 1.6.2rc02 [April 18, 2013]
+  Merge pngtest.c with libpng-1.7.0
+
+Version 1.6.2rc03 [April 22, 2013]
+  Trivial spelling cleanup.
+
+Version 1.6.2rc04 and 1.6.2rc05 [omitted]
+
+Version 1.6.2rc06 [April 24, 2013]
+  Reverted to version 1.6.2rc03.  Recent changes to arm/neon support
+    have been ported to libpng-1.7.0beta09 and will reappear in version
+    1.6.3beta01.
+
+Version 1.6.2 [April 25, 2013]
+  No changes.
+
+Version 1.6.3beta01 [April 25, 2013]
+  Revised stack marking in arm/filter_neon.S and configure.ac.
+  Ensure that NEON filter stuff is completely disabled when switched 'off'.
+    Previously the ARM NEON specific files were still built if the option
+    was switched 'off' as opposed to being explicitly disabled.
+
+Version 1.6.3beta02 [April 26, 2013]
+  Test for 'arm*' not just 'arm' in the host_cpu configure variable.
+  Rebuilt the configure scripts.
+
+Version 1.6.3beta03 [April 30, 2013]
+  Expanded manual paragraph about writing private chunks, particularly
+    the need to call png_set_keep_unknown_chunks() when writing them.
+  Avoid dereferencing NULL pointer possibly returned from
+     png_create_write_struct() (Andrew Church).
+
+Version 1.6.3beta05 [May 9, 2013]
+  Calculate our own zlib windowBits when decoding rather than trusting the
+    CMF bytes in the PNG datastream.
+  Added an option to force maximum window size for inflating, which was
+    the behavior of libpng15 and earlier.
+  Added png-fix-itxt and png-fix-too-far-back to the built programs and
+    removed warnings from the source code and timepng that are revealed as
+    a result.
+  Detect wrong libpng versions linked to png-fix-too-far-back, which currently
+    only works with libpng versions that can be made to reliably fail when
+    the deflate data contains an out-of-window reference.  This means only
+    1.6 and later.
+  Fixed gnu issues: g++ needs a static_cast, gcc 4.4.7 has a broken warning
+    message which it is easier to work round than ignore.
+  Updated contrib/pngminus/pnm2png.c (Paul Stewart):
+    Check for EOF
+    Ignore "#" delimited comments in input file to pnm2png.c.
+    Fixed whitespace handling
+    Added a call to png_set_packing()
+    Initialize dimension values so if sscanf fails at least we have known
+      invalid values.
+  Attempt to detect configuration issues with png-fix-too-far-back, which
+    requires both the correct libpng and the correct zlib to function
+    correctly.
+  Check ZLIB_VERNUM for mismatches, enclose #error in quotes
+  Added information in the documentation about problems with and fixes for
+    the bad CRC and bad iTXt chunk situations.
+
+Version 1.6.3beta06 [May 12, 2013]
+  Allow contrib/pngminus/pnm2png.c to compile without WRITE_INVERT and
+    WRITE_PACK supported (writes error message that it can't read P1 or
+    P4 PBM files).
+  Improved png-fix-too-far-back usage message, added --suffix option.
+  Revised contrib/pngminim/*/makefile to generate pnglibconf.h with the
+    right zlib header files.
+  Separated CPPFLAGS and CFLAGS in contrib/pngminim/*/makefile
+
+Version 1.6.3beta07 [June 8, 2013]
+  Removed a redundant test in png_set_IHDR().
+  Added set(CMAKE_CONFIGURATION_TYPES ...) to CMakeLists.txt (Andrew Hundt)
+  Deleted set(CMAKE_BUILD_TYPE) block from CMakeLists.txt
+  Enclose the prototypes for the simplified write API in
+    #ifdef PNG_STDIO_SUPPORTED/#endif
+  Make ARM NEON support work at compile time (not just configure time).
+    This moves the test on __ARM_NEON__ into pngconf.h to avoid issues when
+    using a compiler that compiles for multiple architectures at one time.
+  Removed PNG_FILTER_OPTIMIZATIONS and PNG_ARM_NEON_SUPPORTED from
+    pnglibconf.h, allowing more of the decisions to be made internally
+    (pngpriv.h) during the compile.  Without this, symbol prefixing is broken
+    under certain circumstances on ARM platforms.  Now only the API parts of
+    the optimizations ('check' vs 'api') are exposed in the public header files
+    except that the new setting PNG_ARM_NEON_OPT documents how libpng makes the
+    decision about whether or not to use the optimizations.
+  Protect symbol prefixing against CC/CPPFLAGS/CFLAGS useage.
+    Previous iOS/Xcode fixes for the ARM NEON optimizations moved the test
+    on __ARM_NEON__ from configure time to compile time.  This breaks symbol
+    prefixing because the definition of the special png_init_filter_functions
+    call was hidden at configure time if the relevant compiler arguments are
+    passed in CFLAGS as opposed to CC.  This change attempts to avoid all
+    the confusion that would result by declaring the init function even when
+    it is not used, so that it will always get prefixed.
+
+Version 1.6.3beta08 [June 18, 2013]
+  Revised libpng.3 so that "doclifter" can process it.
+
+Version 1.6.3beta09 [June 27, 2013]
+  Revised example.c to illustrate use of PNG_DEFAULT_sRGB and PNG_GAMMA_MAC_18
+    as parameters for png_set_gamma().  These have been available since
+    libpng-1.5.4.
+  Renamed contrib/tools/png-fix-too-far-back.c to pngfix.c and revised it
+    to check all compressed chunks known to libpng.
+
+Version 1.6.3beta10 [July 5, 2013]
+  Updated documentation to show default behavior of benign errors correctly.
+  Only compile ARM code when PNG_READ_SUPPORTED is defined.
+  Fixed undefined behavior in contrib/tools/pngfix.c and added new strip
+    option. pngfix relied on undefined behavior and even a simple change from
+    gcc to g++ caused it to fail.  The new strip option 'unsafe' has been
+    implemented and is the default if --max is given.  Option names have
+    been clarified, with --strip=transform now stripping the bKGD chunk,
+    which was stripped previously with --strip=unused.
+  Added all documented chunk types to pngpriv.h
+  Unified pngfix.c source with libpng17.
+
+Version 1.6.3rc01 [July 11, 2013]
+  No changes.
+
+Version 1.6.3 [July 18, 2013]
+  Revised manual about changes in iTXt chunk handling made in libpng-1.6.0.
+  Added "/* SAFE */" comments in pngrutil.c and pngrtran.c where warnings
+    may be erroneously issued by code-checking applications.
+
+Version 1.6.4beta01 [August 21, 2013]
+  Added information about png_set_options() to the manual.
+  Delay calling png_init_filter_functions() until a row with nonzero filter
+    is found.
+
+Version 1.6.4beta02 [August 30, 2013]
+  Fixed inconsistent conditional compilation of png_chunk_unknown_handling()
+    prototype, definition, and usage.  Made it depend on
+    PNG_HANDLE_AS_UNKNOWN_SUPPORTED everywhere.
+
+Version 1.6.4rc01 [September 5, 2013]
+  No changes.
+
+Version 1.6.4 [September 12, 2013]
+  No changes.
+
+Version 1.6.5 [September 14, 2013]
+  Removed two stray lines of code from arm/arm_init.c.
+
+Version 1.6.6 [September 16, 2013]
+  Removed two stray lines of code from arm/arm_init.c, again.
+
+Version 1.6.7beta01 [September 30, 2013]
+  Revised unknown chunk code to correct several bugs in the NO_SAVE_/NO_WRITE
+    combination
+  Allow HANDLE_AS_UNKNOWN to work when other options are configured off. Also
+    fixed the pngminim makefiles to work when $(MAKEFLAGS) contains stuff
+    which terminates the make options (as by default in recent versions of
+    Gentoo).
+  Avoid up-cast warnings in pngvalid.c. On ARM the alignment requirements of
+    png_modifier are greater than that of png_store and as a consequence
+    compilation of pngvalid.c results in a warning about increased alignment
+    requirements because of the bare cast to (png_modifier*). The code is safe,
+    because the pointer is known to point to a stack allocated png_modifier,
+    but this change avoids the warning.
+  Fixed default behavior of ARM_NEON_API. If the ARM NEON API option was
+    compiled without the CHECK option it defaulted to on, not off.
+  Check user callback behavior in pngunknown.c. Previous versions compiled
+    if SAVE_UNKNOWN was not available but did nothing since the callback
+    was never implemented.
+  Merged pngunknown.c with 1.7 version and back ported 1.7 improvements/fixes
+
+Version 1.6.7beta02 [October 12, 2013]
+  Made changes for compatibility with automake 1.14:
+    1) Added the 'compile' program to the list of programs that must be cleaned
+       in autogen.sh
+    2) Added 'subdir-objects' which causes .c files in sub-directories to be
+       compiled such that the corresponding .o files are also in the
+       sub-directory.  This is because automake 1.14 warns that the
+       current behavior of compiling to the top level directory may be removed
+       in the future.
+    3) Updated dependencies on pnglibconf.h to match the new .o locations and
+       added all the files in contrib/libtests and contrib/tools that depend
+       on pnglibconf.h
+    4) Added 'BUILD_SOURCES = pnglibconf.h'; this is the automake recommended
+       way of handling the dependencies of sources that are machine generated;
+       unfortunately it only works if the user does 'make all' or 'make check',
+       so the dependencies (3) are still required.
+  Cleaned up (char*) casts of zlib messages. The latest version of the Intel C
+    compiler complains about casting a string literal as (char*), so copied the
+    treatment of z_const from the library code into pngfix.c
+  Simplified error message code in pngunknown. The simplification has the
+    useful side effect of avoiding a bogus warning generated by the latest
+    version of the Intel C compiler (it objects to
+    condition ? string-literal : string-literal).
+  Make autogen.sh work with automake 1.13 as well as 1.14. Do this by always
+    removing the 1.14 'compile' script but never checking for it.
+
+Version 1.6.7beta03 [October 19, 2013]
+  Added ARMv8 support (James Yu <james.yu at linaro.org>).  Added file
+    arm/filter_neon_intrinsics.c; enable with -mfpu=neon.
+  Revised pngvalid to generate size images with as many filters as it can
+    manage, limited by the number of rows.
+  Cleaned up ARM NEON compilation handling. The tests are now in pngpriv.h
+    and detect the broken GCC compilers.
+
+Version 1.6.7beta04 [October 26, 2013]
+  Allow clang derived from older GCC versions to use ARM intrinsics. This
+    causes all clang builds that use -mfpu=neon to use the intrinsics code,
+    not the assembler code.  This has only been tested on iOS 7. It may be
+    necessary to exclude some earlier clang versions but this seems unlikely.
+  Changed NEON implementation selection mechanism. This allows assembler
+    or intrinsics to be turned on at compile time during the build by defining
+    PNG_ARM_NEON_IMPLEMENTATION to the correct value (2 or 1).  This macro
+    is undefined by default and the build type is selected in pngpriv.h.
+
+Version 1.6.7rc01 [November 2, 2013]
+  No changes.
+
+Version 1.6.7rc02 [November 7, 2013]
+  Fixed #include in filter_neon_intrinsics.c and ctype macros. The ctype char
+    checking macros take an unsigned char argument, not a signed char.
+
+Version 1.6.7 [November 14, 2013]
+  No changes.
+
+Version 1.6.8beta01 [November 24, 2013]
+  Moved prototype for png_handle_unknown() in pngpriv.h outside of
+    the #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED/#endif block.
+  Added "-Wall" to CFLAGS in contrib/pngminim/*/makefile
+  Conditionally compile some unused functions reported by -Wall in
+    pngminim.
+  Fixed 'minimal' builds. Various obviously useful minimal configurations
+    don't build because of missing contrib/libtests test programs and
+    overly complex dependencies in scripts/pnglibconf.dfa. This change
+    adds contrib/conftest/*.dfa files that can be used in automatic build
+    scripts to ensure that these configurations continue to build.
+  Enabled WRITE_INVERT and WRITE_PACK in contrib/pngminim/encoder.
+  Fixed pngvalid 'fail' function declaration on the Intel C Compiler.
+    This reverts to the previous 'static' implementation and works round
+    the 'unused static function' warning by using PNG_UNUSED().
+
+Version 1.6.8beta02 [November 30, 2013]
+  Removed or marked PNG_UNUSED some harmless "dead assignments" reported
+    by clang scan-build.
+  Changed tabs to 3 spaces in png_debug macros and changed '"%s"m'
+    to '"%s" m' to improve portability among compilers.
+  Changed png_free_default() to free() in pngtest.c
+
+Version 1.6.8rc01 [December 12, 2013]
+  Tidied up pngfix inits and fixed pngtest no-write builds.
+
+Version 1.6.8rc02 [December 14, 2013]
+  Handle zero-length PLTE chunk or NULL palette with png_error()
+    instead of png_chunk_report(), which by default issues a warning
+    rather than an error, leading to later reading from a NULL pointer
+    (png_ptr->palette) in png_do_expand_palette(). This is CVE-2013-6954
+    and VU#650142.  Libpng-1.6.1 through 1.6.7 are vulnerable.
+    Libpng-1.6.0 and earlier do not have this bug.
+
+Version 1.6.8 [December 19, 2013]
+  No changes.
+
+Version 1.6.9beta01 [December 26, 2013]
+  Bookkeeping: Moved functions around (no changes). Moved transform
+    function definitions before the place where they are called so that
+    they can be made static. Move the intrapixel functions and the
+    grayscale palette builder out of the png?tran.c files. The latter
+    isn't a transform function and is no longer used internally, and the
+    former MNG specific functions are better placed in pngread/pngwrite.c
+  Made transform implementation functions static. This makes the internal
+    functions called by png_do_{read|write}_transformations static. On an
+    x86-64 DLL build (Gentoo Linux) this reduces the size of the text
+    segment of the DLL by 1208 bytes, about 0.6%. It also simplifies
+    maintenance by removing the declarations from pngpriv.h and allowing
+    easier changes to the internal interfaces.
+  Rebuilt configure scripts with automake-1.14.1 and autoconf-2.69
+    in the tar distributions.
+
+Version 1.6.9beta02 [January 1, 2014]
+  Added checks for libpng 1.5 to pngvalid.c.  This supports the use of
+    this version of pngvalid in libpng 1.5
+  Merged with pngvalid.c from libpng-1.7 changes to create a single
+    pngvalid.c
+  Removed #error macro from contrib/tools/pngfix.c (Thomas Klausner).
+  Merged pngrio.c, pngtrans.c, pngwio.c, and pngerror.c with libpng-1.7.0
+  Merged libpng-1.7.0 changes to make no-interlace configurations work
+    with test programs.
+  Revised pngvalid.c to support libpng 1.5, which does not support the
+    PNG_MAXIMUM_INFLATE_WINDOW option, so #define it out when appropriate in
+    pngvalid.c
+  Allow unversioned links created on install to be disabled in configure.
+    In configure builds 'make install' changes/adds links like png.h
+    and libpng.a to point to the newly installed, versioned, files (e.g.
+    libpng17/png.h and libpng17.a). Three new configure options and some
+    rearrangement of Makefile.am allow creation of these links to be disabled.
+
+Version 1.6.9beta03 [January 10, 2014]
+  Removed potentially misleading warning from png_check_IHDR().
+
+Version 1.6.9beta04 [January 20, 2014]
+  Updated scripts/makefile.* to use CPPFLAGS (Cosmin).
+  Added clang attribute support (Cosmin).
+
+Version 1.6.9rc01 [January 28, 2014]
+  No changes.
+
+Version 1.6.9rc02 [January 30, 2014]
+  Quiet an uninitialized memory warning from VC2013 in png_get_png().
+
+Version 1.6.9 [February 6, 2014]
+
+Version 1.6.10beta01 [February 9, 2014]
+  Backported changes from libpng-1.7.0beta30 and beta31:
+  Fixed a large number of instances where PNGCBAPI was omitted from
+    function definitions.
+  Added pngimage test program for png_read_png() and png_write_png()
+    with two new test scripts.
+  Removed dependence on !PNG_READ_EXPAND_SUPPORTED for calling
+    png_set_packing() in png_read_png().
+  Fixed combination of ~alpha with shift. On read invert alpha, processing
+    occurred after shift processing, which causes the final values to be
+    outside the range that should be produced by the shift. Reversing the
+    order on read makes the two transforms work together correctly and mirrors
+    the order used on write.
+  Do not read invalid sBIT chunks. Previously libpng only checked sBIT
+    values on write, so a malicious PNG writer could therefore cause
+    the read code to return an invalid sBIT chunk, which might lead to
+    application errors or crashes.  Such chunks are now skipped (with
+    chunk_benign_error).
+  Make png_read_png() and png_write_png() prototypes in png.h depend
+    upon PNG_READ_SUPPORTED and PNG_WRITE_SUPPORTED.
+  Support builds with unsupported PNG_TRANSFORM_* values.  All of the
+    PNG_TRANSFORM_* values are always defined in png.h and, because they
+    are used for both read and write in some cases, it is not reliable
+    to #if out ones that are totally unsupported. This change adds error
+    detection in png_read_image() and png_write_image() to do a
+    png_app_error() if the app requests something that cannot be done
+    and it adds corresponding code to pngimage.c to handle such options
+    by not attempting to test them.
+
+Version 1.6.10beta02 [February 23, 2014]
+  Moved redefines of png_error(), png_warning(), png_chunk_error(),
+    and png_chunk_warning() from pngpriv.h to png.h to make them visible
+    to libpng-calling applications.
+  Moved OS dependent code from arm/arm_init.c, to allow the included
+    implementation of the ARM NEON discovery function to be set at
+    build-time and provide sample implementations from the current code in the
+    contrib/arm-neon subdirectory. The __linux__ code has also been changed to
+    compile and link on Android by using /proc/cpuinfo, and the old linux code
+    is in contrib/arm-neon/linux-auxv.c.  The new code avoids POSIX and Linux
+    dependencies apart from opening /proc/cpuinfo and is C90 compliant.
+  Check for info_ptr == NULL early in png_read_end() so we don't need to
+    run all the png_handle_*() and depend on them to return if info_ptr == NULL.
+    This improves the performance of png_read_end(png_ptr, NULL) and makes
+    it more robust against future programming errors.
+  Check for __has_extension before using it in pngconf.h, to
+    support older Clang versions (Jeremy Sequoia).
+  Treat CRC error handling with png_set_crc_action(), instead of with
+    png_set_benign_errors(), which has been the case since libpng-1.6.0beta18.
+  Use a user warning handler in contrib/gregbook/readpng2.c instead of default,
+    so warnings will be put on stderr even if libpng has CONSOLE_IO disabled.
+  Added png_ptr->process_mode = PNG_READ_IDAT_MODE in png_push_read_chunk
+    after recognizing the IDAT chunk, which avoids an infinite loop while
+    reading a datastream whose first IDAT chunk is of zero-length.
+    This fixes CERT VU#684412 and CVE-2014-0333.
+  Don't recognize known sRGB profiles as sRGB if they have been hacked,
+    but don't reject them and don't issue a copyright violation warning.
+
+Version 1.6.10beta03 [February 25, 2014]
+  Moved some documentation from png.h to libpng.3 and libpng-manual.txt
+  Minor editing of contrib/arm-neon/README and contrib/examples/*.c
+
+Version 1.6.10rc01 [February 27, 2014]
+  Fixed typos in the manual and in scripts/pnglibconf.dfa (CFLAGS -> CPPFLAGS
+    and PNG_USR_CONFIG -> PNG_USER_CONFIG).
+
+Version 1.6.10rc02 [February 28, 2014]
+  Removed unreachable return statement after png_chunk_error()
+    in pngrutil.c
+
+Version 1.6.10rc03 [March 4, 2014]
+  Un-deprecated png_data_freer().
+
+Version 1.6.10 [March 6, 2014]
+  No changes.
+
+Version 1.6.11beta01 [March 17, 2014]
+  Use "if (value != 0)" instead of "if (value)" consistently.
+  Changed ZlibSrcDir from 1.2.5 to 1.2.8 in projects/vstudio.
+  Moved configuration information from the manual to the INSTALL file.
+
+Version 1.6.11beta02 [April 6, 2014]
+  Removed #if/#else/#endif from inside two pow() calls in pngvalid.c because
+    they were handled improperly by Portland Group's PGI-14.1 - PGI-14.3
+    when using its "__builtin_pow()" function.
+  Silence 'unused parameter' build warnings (Cosmin Truta).
+  $(CP) is now used alongside $(RM_F).  Also, use 'copy' instead of 'cp'
+    where applicable, and applied other minor makefile changes (Cosmin).
+  Don't warn about invalid dimensions exceeding user limits (Cosmin).
+  Allow an easy replacement of the default pre-built configuration
+    header with a custom header, via the make PNGLIBCONF_H_PREBUILT
+    macro (Cosmin).
+
+Version 1.6.11beta03 [April 6, 2014]
+  Fixed a typo in pngrutil.c, introduced in libpng-1.5.6, that interferes
+    with "blocky" expansion of sub-8-bit interlaced PNG files (Eric Huss).
+  Optionally use  __builtin_bswap16() in png_do_swap().
+
+Version 1.6.11beta04 [April 19, 2014]
+  Made progressive reading of interlaced images consistent with the
+    behavior of the sequential reader and consistent with the manual, by
+    moving some code out of the PNG_READ_INTERLACING_SUPPORTED blocks. The
+    row_callback now receives the proper pass number and unexpanded rows, when
+    png_combine_row() isn't built or used, and png_set_interlace_handling()
+    is not called.
+  Allow PNG_sRGB_PROFILE_CHECKING = (-1) to mean no sRGB profile checking.
+
+Version 1.6.11beta05 [April 26, 2014]
+  Do not reject ICC V2 profiles that lack padding (Kai-Uwe Behrmann).
+  Relocated closing bracket of the sRGB profile test loop to avoid getting
+    "Not recognizing known sRGB profile that has been edited" warning for
+    ICC V2 profiles that lack the MD5 signature in the profile header.
+
+Version 1.6.11beta06 [May 19, 2014]
+  Added PNG_SKIP_sRGB_CHECK_PROFILE choice for png_set_option().
+
+Version 1.6.11rc01 [May 27, 2014]
+  No changes.
+
+Version 1.6.11rc02 [June 3, 2014]
+  Test ZLIB_VERNUM instead of PNG_ZLIB_VERNUM in contrib/tools/pngfix.c
+
+Version 1.6.11 [June 5, 2014]
+  No changes.
+
+Version 1.6.12rc01 [June 6, 2014]
+  Relocated new code from 1.6.11beta06 in png.c to a point after the
+    declarations (Max Stepin).
+
+Version 1.6.12rc02 [June 7, 2014]
+  Changed file permissions of contrib/tools/intgamma.sh,
+    test-driver, and compile from 0644 to 0755 (Cosmin).
+
+Version 1.6.12rc03 [June 8, 2014]
+  Ensure "__has_attribute()" macro exists before trying to use it with
+    old clang compilers (MacPorts Ticket #43939).
+
+Version 1.6.12 [June 12, 2014]
+  No changes.
+
+Version 1.6.13beta01 [July 4, 2014]
+  Quieted -Wsign-compare and -Wclobber compiler warnings in
+    contrib/pngminus/*.c
+  Added "(void) png_ptr;" where needed in contrib/gregbook to quiet
+    compiler complaints about unused pointers.
+  Split a long output string in contrib/gregbook/rpng2-x.c.
+  Added "PNG_SET_OPTION" requirement for sRGB chunk support to pnglibconf.dfa,
+    Needed for write-only support (John Bowler).
+  Changed "if defined(__ARM_NEON__)" to
+    "if (defined(__ARM_NEON__) || defined(__ARM_NEON))" (James Wu).
+  Fixed clang no-warning builds: png_digit was defined but never used.
+    
+Version 1.6.13beta02 [July 21, 2014]
+  Fixed an incorrect separator ("/" should be "\") in scripts/makefile.vcwin32
+    (bug report from Wolfgang S. Kechel).  Bug was introduced in libpng-1.6.11.
+    Also fixed makefile.bc32, makefile.bor, makefile.msc, makefile.intel, and
+    makefile.tc3 similarly.
+
+Version 1.6.13beta03 [August 3, 2014]
+  Removed scripts/makefile.elf. It has not worked since libpng-1.5.0beta14
+    due to elimination of the PNG_FUNCTION_EXPORT and PNG_DATA_EXPORT
+    definitions from pngconf.h.
+  Ensure that CMakeLists.txt makes the target "lib" directory before making
+    symbolic link into it (SourceForge bug report #226 by Rolf Timmermans).
+
+Version 1.6.13beta04 [August 8, 2014]
+  Added opinion that the ECCN (Export Control Classification Number) for
+    libpng is EAR99 to the README file.
+  Eliminated use of "$<" in makefile explicit rules, when copying
+    $PNGLIBCONF_H_PREBUILT.  This does not work on some versions of make;
+    bug introduced in libpng version 1.6.11.
+
+Version 1.6.13rc01 [August 14, 2014]
+  Made "ccopts" agree with "CFLAGS" in scripts/makefile.hp* and makefile.*sunu
+
+Version 1.6.13 [August 21, 2014]
+  No changes.
+
+Version 1.6.14beta01 [September 14, 2014]
+  Guard usage of png_ptr->options with #ifdef PNG_SET_OPTION_SUPPORTED.
+  Do not build contrib/tools/pngfix.c when PNG_SETJMP_NOT_SUPPORTED,
+    to allow "make" to complete without setjmp support (bug report by
+    Claudio Fontana)
+  Add "#include <setjmp.h>" to contrib/tools/pngfix.c (John Bowler)
+
+Version 1.6.14beta02 [September 18, 2014]
+  Use nanosleep() instead of usleep() in contrib/gregbook/rpng2-x.c
+    because usleep() is deprecated.
+  Define usleep() in contrib/gregbook/rpng2-x.c if not already defined
+    in unistd.h and nanosleep() is not available; fixes error introduced
+    in libpng-1.6.13.
+  Disable floating point exception handling in pngvalid.c when
+    PNG_FLOATING_ARITHMETIC is not supported (bug report by "zootus
+    at users.sourceforge.net").
+
+Version 1.6.14beta03 [September 19, 2014]
+  Define FE_DIVBYZERO, FE_INVALID, and FE_OVERFLOW in pngvalid.c if not
+    already defined.  Revert floating point exception handling in pngvalid.c
+    to version 1.6.14beta01 behavior.
+
+Version 1.6.14beta04 [September 27, 2014]
+  Fixed incorrect handling of the iTXt compression flag in pngrutil.c
+    (bug report by Shunsaku Hirata).  Bug was introduced in libpng-1.6.0.
+
+Version 1.6.14beta05 [October 1, 2014]
+  Added "option READ_iCCP enables READ_COMPRESSED_TEXT" to pnglibconf.dfa
+
+Version 1.6.14beta06 [October 5, 2014]
+  Removed unused "text_len" parameter from private function png_write_zTXt().
+  Conditionally compile some code in png_deflate_claim(), when
+    PNG_WARNINGS_SUPPORTED and PNG_ERROR_TEXT_SUPPORTED are disabled.
+  Replaced repeated code in pngpread.c with PNG_PUSH_SAVE_BUFFER_IF_FULL.
+  Added "chunk iTXt enables TEXT" and "chunk zTXt enables TEXT"
+    to pnglibconf.dfa.
+  Removed "option READ_COMPRESSED_TEXT enables READ_TEXT" from pnglibconf.dfa,
+    to make it possible to configure a libpng that supports iCCP but not TEXT.
+
+Version 1.6.14beta07 [October 7, 2014]
+  Removed "option WRITE_COMPRESSED_TEXT enables WRITE_TEXT" from pnglibconf.dfa
+  Only mark text chunks as written after successfully writing them.
+
+Version 1.6.14rc01 [October 15, 2014]
+  Fixed some typos in comments.
+
+Version 1.6.14rc02 [October 17, 2014]
+  Changed png_convert_to_rfc_1123() to png_convert_to_rfc_1123_buffer()
+    in the manual, to reflect the change made in libpng-1.6.0.
+  Updated README file to explain that direct access to the png_struct
+    and info_struct members has not been permitted since libpng-1.5.0.
+
+Version 1.6.14 [October 23, 2014]
+  No changes.
+
+Version 1.6.15beta01 [October 29, 2014]
+  Changed "if (!x)" to "if (x == 0)" and "if (x)" to "if (x != 0)"
+  Simplified png_free_data().
+  Added missing "ptr = NULL" after some instances of png_free().
+
+Version 1.6.15beta02 [November 1, 2014]
+  Changed remaining "if (!x)" to "if (x == 0)" and "if (x)" to "if (x != 0)"
+
+Version 1.6.15beta03 [November 3, 2014]
+  Added PNG_USE_ARM_NEON configuration flag (Marcin Juszkiewicz).
+
+Version 1.6.15beta04 [November 4, 2014]
+  Removed new PNG_USE_ARM_NEON configuration flag and made a one-line
+    revision to configure.ac to support ARM on aarch64 instead (John Bowler).
+
+Version 1.6.15beta05 [November 5, 2014]
+  Use png_get_libpng_ver(NULL) instead of PNG_LIBPNG_VER_STRING in
+    example.c, pngtest.c, and applications in the contrib directory.
+  Avoid out-of-bounds memory access in png_user_version_check().
+  Simplified and future-proofed png_user_version_check().
+  Fixed GCC unsigned int->float warnings. Various versions of GCC
+    seem to generate warnings when an unsigned value is implicitly
+    converted to double. This is probably a GCC bug but this change
+    avoids the issue by explicitly converting to (int) where safe.
+  Free all allocated memory in pngimage. The file buffer cache was left
+    allocated at the end of the program, harmless but it causes memory
+    leak reports from clang.
+  Fixed array size calculations to avoid warnings. At various points
+    in the code the number of elements in an array is calculated using
+    sizeof.  This generates a compile time constant of type (size_t) which
+    is then typically assigned to an (unsigned int) or (int). Some versions
+    of GCC on 64-bit systems warn about the apparent narrowing, even though
+    the same compiler does apparently generate the correct, in-range,
+    numeric constant.  This adds appropriate, safe, casts to make the
+    warnings go away.
+
+Version 1.6.15beta06 [November 6, 2014]
+  Reverted use png_get_libpng_ver(NULL) instead of PNG_LIBPNG_VER_STRING
+    in the manual, example.c, pngtest.c, and applications in the contrib
+    directory.  It was incorrect advice.
+
+Version 1.6.15beta07 [November 7, 2014]
+  Removed #ifdef PNG_16BIT_SUPPORTED/#endif around png_product2(); it is
+    needed by png_reciprocal2().
+  Added #ifdef PNG_16BIT_SUPPORTED/#endif around png_log16bit() and
+    png_do_swap().
+  Changed all "#endif /* PNG_FEATURE_SUPPORTED */" to "#endif /* FEATURE */"
+
+Version 1.6.15beta08 [November 8, 2014]
+  More housecleaning in *.h
+
+Version 1.6.15rc01 [November 13, 2014]
+
+Version 1.6.15rc02 [November 14, 2014]
+  The macros passed in the command line to Borland make were ignored if
+    similarly-named macros were already defined in makefiles. This behavior
+    is different from POSIX make and other make programs.  Surround the
+    macro definitions with ifndef guards (Cosmin).
+
+Version 1.6.15rc03 [November 16, 2014]
+  Added "-D_CRT_SECURE_NO_WARNINGS" to CFLAGS in scripts/makefile.vcwin32.
+  Removed the obsolete $ARCH variable from scripts/makefile.darwin.
+
+Version 1.6.15 [November 20, 2014]
+  No changes.
+
+Version 1.6.16beta01 [December 14, 2014]
+  Added ".align 2" to arm/filter_neon.S to support old GAS assemblers that
+    don't do alignment correctly.
+  Revised Makefile.am and scripts/symbols.dfn to work with MinGW/MSYS
+    (Bob Friesenhahn).
+
+Version 1.6.16beta02 [December 15, 2014]
+  Revised Makefile.am and scripts/*.dfn again to work with MinGW/MSYS;
+    renamed scripts/*.dfn to scripts/*.c (John Bowler).
+
+Version 1.6.16beta03 [December 21, 2014]
+  Quiet a "comparison always true" warning in pngstest.c (John Bowler).
+
+Version 1.6.16rc01 [December 21, 2014]
+  Restored a test on width that was removed from png.c at libpng-1.6.9
+    (Bug report by Alex Eubanks, CVE-2015-0973).
+
+Version 1.6.16rc02 [December 21, 2014]
+  Undid the update to pngrutil.c in 1.6.16rc01.
+
+Version 1.6.16rc03 [December 21, 2014]
+  Fixed an overflow in png_combine_row() with very wide interlaced images
+    (Bug report and fix by John Bowler, CVE-2014-9495).
+
+Version 1.6.16 [December 22, 2014]
+  No changes.
+
+Version 1.6.17beta01 [January 29, 2015]
+  Removed duplicate PNG_SAFE_LIMITS_SUPPORTED handling from pngconf.h
+  Corrected the width limit calculation in png_check_IHDR().
+  Removed user limits from pngfix. Also pass NULL pointers to
+    png_read_row to skip the unnecessary row de-interlace stuff.
+  Added testing of png_set_packing() to pngvalid.c
+  Regenerated configure scripts in the *.tar distributions with libtool-2.4.4
+  Implement previously untested cases of libpng transforms in pngvalid.c
+  Fixed byte order in 2-byte filler, in png_do_read_filler().
+  Made the check for out-of-range values in png_set_tRNS() detect
+    values that are exactly 2^bit_depth, and work on 16-bit platforms.
+  Merged some parts of libpng-1.6.17beta01 and libpng-1.7.0beta47.
+  Added #ifndef __COVERITY__ where needed in png.c, pngrutil.c and
+    pngset.c to avoid warnings about dead code.
+  Added "& 0xff" to many instances of expressions that are typecast
+    to (png_byte), to avoid Coverity gripes.
+
+Version 1.6.17beta02 [February 7, 2015]
+  Work around one more Coverity-scan dead-code warning.
+  Do not build png_product2() when it is unused.
+
+Version 1.6.17beta03 [February 17, 2015]
+  Display user limits in the output from pngtest.
+  Eliminated the PNG_SAFE_LIMITS macro and restored the 1-million-column
+    and 1-million-row default limits in pnglibconf.dfa, that can be reset
+    by the user at build time or run time.  This provides a more robust
+    defense against DOS and as-yet undiscovered overflows.
+
+Version 1.6.17beta04 [February 21, 2015]
+  Added PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED macro, on by default.
+  Allow user to call png_get_IHDR() with NULL arguments (Reuben Hawkins).
+  Rebuilt configure scripts with automake-1.15 and libtool-2.4.6
+
+Version 1.6.17beta05 [February 25, 2015]
+  Restored compiling of png_reciprocal2 with PNG_NO_16BIT.
+
+Version 1.6.17beta06 [February 27, 2015]
+  Moved png_set_filter() prototype into a PNG_WRITE_SUPPORTED block
+    of png.h.
+  Avoid runtime checks when converting integer to png_byte with
+    Visual Studio (Sergey Kosarevsky)
+
+Version 1.6.17rc01 [March 4, 2015]
+  No changes.
+
+Version 1.6.17rc02 [March 9, 2015]
+  Removed some comments that the configure script did not handle
+    properly from scripts/pnglibconf.dfa and pnglibconf.h.prebuilt.
+  Free the unknown_chunks structure even when it contains no data.
+
+Version 1.6.17rc03 [March 12, 2015]
+  Updated CMakeLists.txt to add OSX framework, change YES/NO to ON/OFF
+    for consistency, and remove some useless tests (Alexey Petruchik).
+
+Version 1.6.17rc04 [March 16, 2015]
+  Remove pnglibconf.h, pnglibconf.c, and pnglibconf.out instead of
+    pnglibconf.* in "make clean" (Cosmin).
+  Fix bug in calculation of maxbits, in png_write_sBIT, introduced
+    in libpng-1.6.17beta01 (John Bowler).
+
+Version 1.6.17rc05 [March 21, 2015]
+  Define PNG_FILTER_* and PNG_FILTER_VALUE_* in png.h even when WRITE
+    is not supported (John Bowler).  This fixes an error introduced in
+    libpng-1.6.17beta06.
+  Reverted "& 0xff" additions of version 1.6.17beta01. Libpng passes
+    the Coverity scan without them.
+
+Version 1.6.17rc06 [March 23, 2015]
+  Remove pnglibconf.dfn and pnglibconf.pre with "make clean".
+  Reformatted some "&0xff" instances to "& 0xff".
+  Fixed simplified 8-bit-linear to sRGB alpha. The calculated alpha
+    value was wrong.  It's not clear if this affected the final stored
+    value; in the obvious code path the upper and lower 8-bits of the
+    alpha value were identical and the alpha was truncated to 8-bits
+    rather than dividing by 257 (John Bowler).
+
+Version 1.6.17 [March 26, 2015]
+  No changes.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
@@ -3861,4 +5212,3 @@ to subscribe)
 or to glennrp at users.sourceforge.net
 
 Glenn R-P
-#endif
diff --git a/src/3rdparty/libpng/INSTALL b/src/3rdparty/libpng/INSTALL
index e6979c6..a294ffe 100644
--- a/src/3rdparty/libpng/INSTALL
+++ b/src/3rdparty/libpng/INSTALL
@@ -1,32 +1,69 @@
 
 Installing libpng
 
+Contents
+
+   I. Simple installation
+  II. Rebuilding the configure scripts
+ III. Using scripts/makefile*
+  IV. Using cmake
+   V. Directory structure
+  VI. Building with project files
+ VII. Building with makefiles
+VIII. Configuring libpng for 16-bit platforms
+  IX. Configuring for DOS
+   X. Configuring for Medium Model
+  XI. Prepending a prefix to exported symbols
+ XII. Configuring for compiler xxx:
+XIII. Removing unwanted object code
+ XIV. Changes to the build and configuration of libpng in libpng-1.5.x
+  XV. Setjmp/longjmp issues
+ XVI. Other sources of information about libpng
+
+I. Simple installation
+
 On Unix/Linux and similar systems, you can simply type
 
     ./configure [--prefix=/path]
     make check
     make install
 
-and ignore the rest of this document.
+and ignore the rest of this document.  "/path" is the path to the directory
+where you want to install the libpng "lib", "include", and "bin"
+subdirectories.
+
+If you downloaded a GIT clone, you will need to run ./autogen.sh before
+running ./configure, to create "configure" and "Makefile.in" which are
+not included in the GIT repository.
+
+Note that "configure" is only included in the "*.tar" distributions and not
+in the "*.zip" or "*.7z" distributions. If you downloaded one of those
+distributions, see "Building with project files" or "Building with makefiles",
+below.
 
-If configure does not work on your system and you have a reasonably
-up-to-date set of tools, running ./autogen.sh before running ./configure
-may fix the problem.  You can also run the individual commands in
-autogen.sh with the --force option, if supported by your version of
-the tools.  To be really sure that you aren't using any of the included
-pre-built scripts, you can do this:
+II. Rebuilding the configure scripts
+
+If configure does not work on your system, or if you have a need to
+change configure.ac or Makefile.am, and you have a reasonably
+up-to-date set of tools, running ./autogen.sh in a git clone before
+running ./configure may fix the problem.  To be really sure that you
+aren't using any of the included pre-built scripts, you can do this:
 
     ./configure --enable-maintainer-mode
     make maintainer-clean
-    ./autogen.sh
+    ./autogen.sh --maintainer --clean
+    ./autogen.sh --maintainer
     ./configure [--prefix=/path] [other options]
     make
     make install
     make check
 
+III. Using scripts/makefile*
+
 Instead, you can use one of the custom-built makefiles in the
 "scripts" directory
 
+    cp scripts/pnglibconf.h.prebuilt pnglibconf.h
     cp scripts/makefile.system makefile
     make test
     make install
@@ -38,8 +75,28 @@ Or you can use one of the "projects" in the "projects" directory.
 
 Before installing libpng, you must first install zlib, if it
 is not already on your system.  zlib can usually be found
-wherever you got libpng.  zlib can be placed in another directory,
-at the same level as libpng.
+wherever you got libpng; otherwise go to http://zlib.net.  You can place
+zlib in in the same directory as libpng or in another directory.
+
+If your system already has a preinstalled zlib you will still need
+to have access to the zlib.h and zconf.h include files that
+correspond to the version of zlib that's installed.
+
+If you wish to test with a particular zlib that is not first in the
+standard library search path, put ZLIBLIB, ZLIBINC, CPPFLAGS, LDFLAGS,
+and LD_LIBRARY_PATH in your environment before running "make test"
+or "make distcheck":
+
+ZLIBLIB=/path/to/lib export ZLIBLIB
+ZLIBINC=/path/to/include export ZLIBINC
+CPPFLAGS="-I$ZLIBINC" export CPPFLAGS
+LDFLAGS="-L$ZLIBLIB" export LDFLAGS
+LD_LIBRARY_PATH="$ZLIBLIB:$LD_LIBRARY_PATH" export LD_LIBRARY_PATH
+
+If you are using one of the makefile scripts, put ZLIBLIB and ZLIBINC
+in your environment and type "make ZLIBLIB=$ZLIBLIB ZLIBINC=$ZLIBINC test".
+
+IV. Using cmake
 
 If you want to use "cmake" (see www.cmake.org), type
 
@@ -47,13 +104,15 @@ If you want to use "cmake" (see www.cmake.org), type
    make
    make install
 
-If your system already has a preinstalled zlib you will still need
-to have access to the zlib.h and zconf.h include files that
-correspond to the version of zlib that's installed.
+As when using the simple configure method described above, "/path" points to
+the installation directory where you want to put the libpng "lib", "include",
+and "bin" subdirectories.
+
+V. Directory structure
 
 You can rename the directories that you downloaded (they
-might be called "libpng-x.y.z" or "libpngNN" and "zlib-1.2.5"
-or "zlib125") so that you have directories called "zlib" and "libpng".
+might be called "libpng-x.y.z" or "libpngNN" and "zlib-1.2.8"
+or "zlib128") so that you have directories called "zlib" and "libpng".
 
 Your directory structure should look like this:
 
@@ -61,8 +120,7 @@ Your directory structure should look like this:
       libpng  (this directory)
           INSTALL (this file)
           README
-          *.h
-          *.c
+          *.h, *.c  => libpng source files
           CMakeLists.txt    =>  "cmake" script
           configuration files:
              configure.ac, configure, Makefile.am, Makefile.in,
@@ -70,14 +128,10 @@ Your directory structure should look like this:
              libpng-config.in, aclocal.m4, config.h.in, config.sub,
              depcomp, install-sh, mkinstalldirs, test-pngtest.sh
           contrib
-             gregbook
-             pngminim
-             pngminus
-             pngsuite
-             visupng
+             arm-neon, conftest, examples, gregbook, libtests, pngminim,
+             pngminus, pngsuite, tools, visupng
           projects
-             visualc71
-             vstudio
+             cbuilder5, owatcom, visualc71, vstudio, xcode
           scripts
              makefile.*
              *.def (module definition files)
@@ -85,29 +139,31 @@ Your directory structure should look like this:
           pngtest.png
           etc.
       zlib
-          README
-          *.h
-          *.c
-          contrib
-          etc.
+          README, *.h, *.c contrib, etc.
 
 If the line endings in the files look funny, you may wish to get the other
 distribution of libpng.  It is available in both tar.gz (UNIX style line
 endings) and zip (DOS style line endings) formats.
 
+VI. Building with project files
+
 If you are building libpng with MSVC, you can enter the
-libpng projects\visualc6 or visualc71 directory and follow the instructions
+libpng projects\visualc71 or vstudio directory and follow the instructions
 in README.txt.
 
 Otherwise enter the zlib directory and follow the instructions in zlib/README,
 then come back here and run "configure" or choose the appropriate
 makefile.sys in the scripts directory.
 
+VII. Building with makefiles
+
 Copy the file (or files) that you need from the
 scripts directory into this directory, for example
 
    MSDOS example: copy scripts\makefile.msc makefile
-   UNIX example:    cp scripts/makefile.std makefile
+                  copy scripts\pnglibconf.h.prebuilt pnglibconf.h
+   UNIX example:  cp scripts/makefile.std makefile
+                  cp scripts/pnglibconf.h.prebuilt pnglibconf.h
 
 Read the makefile to see if you need to change any source or
 target directories to match your preferences.
@@ -130,6 +186,202 @@ do that, run "make install" in the zlib directory first if necessary).
 Some also allow you to run "make test-installed" after you have
 run "make install".
 
+VIII. Configuring libpng for 16-bit platforms
+
+You will want to look into zconf.h to tell zlib (and thus libpng) that
+it cannot allocate more than 64K at a time.  Even if you can, the memory
+won't be accessible.  So limit zlib and libpng to 64K by defining MAXSEG_64K.
+
+IX. Configuring for DOS
+
+For DOS users who only have access to the lower 640K, you will
+have to limit zlib's memory usage via a png_set_compression_mem_level()
+call.  See zlib.h or zconf.h in the zlib library for more information.
+
+X. Configuring for Medium Model
+
+Libpng's support for medium model has been tested on most of the popular
+compilers.  Make sure MAXSEG_64K gets defined, USE_FAR_KEYWORD gets
+defined, and FAR gets defined to far in pngconf.h, and you should be
+all set.  Everything in the library (except for zlib's structure) is
+expecting far data.  You must use the typedefs with the p or pp on
+the end for pointers (or at least look at them and be careful).  Make
+note that the rows of data are defined as png_bytepp, which is
+an "unsigned char far * far *".
+
+XI. Prepending a prefix to exported symbols
+
+Starting with libpng-1.6.0, you can configure libpng (when using the
+"configure" script) to prefix all exported symbols by means of the
+configuration option "--with-libpng-prefix=FOO_", where FOO_ can be any
+string beginning with a letter and containing only uppercase
+and lowercase letters, digits, and the underscore (i.e., a C language
+identifier).  This creates a set of macros in pnglibconf.h, so this is
+transparent to applications; their function calls get transformed by
+the macros to use the modified names.
+
+XII. Configuring for compiler xxx:
+
+All includes for libpng are in pngconf.h.  If you need to add, change
+or delete an include, this is the place to do it.
+The includes that are not needed outside libpng are placed in pngpriv.h,
+which is only used by the routines inside libpng itself.
+The files in libpng proper only include pngpriv.h and png.h, which
+in turn includes pngconf.h and, as of libpng-1.5.0, pnglibconf.h.
+As of libpng-1.5.0, pngpriv.h also includes three other private header
+files, pngstruct.h, pnginfo.h, and pngdebug.h, which contain material
+that previously appeared in the public headers.
+
+XIII. Removing unwanted object code
+
+There are a bunch of #define's in pngconf.h that control what parts of
+libpng are compiled.  All the defines end in _SUPPORTED.  If you are
+never going to use a capability, you can change the #define to #undef
+before recompiling libpng and save yourself code and data space, or
+you can turn off individual capabilities with defines that begin with
+PNG_NO_.
+
+In libpng-1.5.0 and later, the #define's are in pnglibconf.h instead.
+
+You can also turn all of the transforms and ancillary chunk capabilities
+off en masse with compiler directives that define
+PNG_NO_READ[or WRITE]_TRANSFORMS, or PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS,
+or all four, along with directives to turn on any of the capabilities that
+you do want.  The PNG_NO_READ[or WRITE]_TRANSFORMS directives disable the
+extra transformations but still leave the library fully capable of reading
+and writing PNG files with all known public chunks. Use of the
+PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS directive produces a library
+that is incapable of reading or writing ancillary chunks.  If you are
+not using the progressive reading capability, you can turn that off
+with PNG_NO_PROGRESSIVE_READ (don't confuse this with the INTERLACING
+capability, which you'll still have).
+
+All the reading and writing specific code are in separate files, so the
+linker should only grab the files it needs.  However, if you want to
+make sure, or if you are building a stand alone library, all the
+reading files start with "pngr" and all the writing files start with "pngw".
+The files that don't match either (like png.c, pngtrans.c, etc.)
+are used for both reading and writing, and always need to be included.
+The progressive reader is in pngpread.c
+
+If you are creating or distributing a dynamically linked library (a .so
+or DLL file), you should not remove or disable any parts of the library,
+as this will cause applications linked with different versions of the
+library to fail if they call functions not available in your library.
+The size of the library itself should not be an issue, because only
+those sections that are actually used will be loaded into memory.
+
+XIV. Changes to the build and configuration of libpng in libpng-1.5.x
+
+Details of internal changes to the library code can be found in the CHANGES
+file and in the GIT repository logs.  These will be of no concern to the vast
+majority of library users or builders; however, the few who configure libpng
+to a non-default feature set may need to change how this is done.
+
+There should be no need for library builders to alter build scripts if
+these use the distributed build support - configure or the makefiles -
+however, users of the makefiles may care to update their build scripts
+to build pnglibconf.h where the corresponding makefile does not do so.
+
+Building libpng with a non-default configuration has changed completely.
+The old method using pngusr.h should still work correctly even though the
+way pngusr.h is used in the build has been changed; however, library
+builders will probably want to examine the changes to take advantage of
+new capabilities and to simplify their build system.
+
+A. Specific changes to library configuration capabilities
+
+The exact mechanism used to control attributes of API functions has
+changed.  A single set of operating system independent macro definitions
+is used and operating system specific directives are defined in
+pnglibconf.h
+
+As part of this the mechanism used to choose procedure call standards on
+those systems that allow a choice has been changed.  At present this only
+affects certain Microsoft (DOS, Windows) and IBM (OS/2) operating systems
+running on Intel processors.  As before, PNGAPI is defined where required
+to control the exported API functions; however, two new macros, PNGCBAPI
+and PNGCAPI, are used instead for callback functions (PNGCBAPI) and
+(PNGCAPI) for functions that must match a C library prototype (currently
+only png_longjmp_ptr, which must match the C longjmp function.)  The new
+approach is documented in pngconf.h
+
+Despite these changes, libpng 1.5.0 only supports the native C function
+calling standard on those platforms tested so far (__cdecl on Microsoft
+Windows).  This is because the support requirements for alternative
+calling conventions seem to no longer exist.  Developers who find it
+necessary to set PNG_API_RULE to 1 should advise the mailing list
+(png-mng-implement) of this and library builders who use Openwatcom and
+therefore set PNG_API_RULE to 2 should also contact the mailing list.
+
+B. Changes to the configuration mechanism
+
+Prior to libpng-1.5.0 library builders who needed to configure libpng
+had either to modify the exported pngconf.h header file to add system
+specific configuration or had to write feature selection macros into
+pngusr.h and cause this to be included into pngconf.h by defining
+PNG_USER_CONFIG. The latter mechanism had the disadvantage that an
+application built without PNG_USER_CONFIG defined would see the
+unmodified, default, libpng API and thus would probably fail to link.
+
+These mechanisms still work in the configure build and in any makefile
+build that builds pnglibconf.h, although the feature selection macros
+have changed somewhat as described above.  In 1.5.0, however, pngusr.h is
+processed only once, at the time the exported header file pnglibconf.h is
+built.  pngconf.h no longer includes pngusr.h; therefore, pngusr.h is ignored
+after the build of pnglibconf.h and it is never included in an application
+build.
+
+The formerly used alternative of adding a list of feature macros to the
+CPPFLAGS setting in the build also still works; however, the macros will be
+copied to pnglibconf.h and this may produce macro redefinition warnings
+when the individual C files are compiled.
+
+All configuration now only works if pnglibconf.h is built from
+scripts/pnglibconf.dfa.  This requires the program awk.  Brian Kernighan
+(the original author of awk) maintains C source code of that awk and this
+and all known later implementations (often called by subtly different
+names - nawk and gawk for example) are adequate to build pnglibconf.h.
+The Sun Microsystems (now Oracle) program 'awk' is an earlier version
+and does not work; this may also apply to other systems that have a
+functioning awk called 'nawk'.
+
+Configuration options are now documented in scripts/pnglibconf.dfa.  This
+file also includes dependency information that ensures a configuration is
+consistent; that is, if a feature is switched off, dependent features are
+also switched off.  As a recommended alternative to using feature macros in
+pngusr.h a system builder may also define equivalent options in pngusr.dfa
+(or, indeed, any file) and add that to the configuration by setting
+DFA_XTRA to the file name.  The makefiles in contrib/pngminim illustrate
+how to do this, and also illustrate a case where pngusr.h is still required.
+
+After you have built libpng, the definitions that were recorded in
+pnglibconf.h are available to your application (pnglibconf.h is included
+in png.h and gets installed alongside png.h and pngconf.h in your
+$PREFIX/include directory).  Do not edit pnglibconf.h after you have built
+libpng, because than the settings would not accurately reflect the settings
+that were used to build libpng.
+
+XV. Setjmp/longjmp issues
+
+Libpng uses setjmp()/longjmp() for error handling.  Unfortunately setjmp()
+is known to be not thread-safe on some platforms and we don't know of
+any platform where it is guaranteed to be thread-safe.  Therefore, if
+your application is going to be using multiple threads, you should
+configure libpng with PNG_NO_SETJMP in your pngusr.dfa file, with
+-DPNG_NO_SETJMP on your compile line, or with
+
+  #undef PNG_SETJMP_SUPPORTED
+
+in your pnglibconf.h or pngusr.h.
+
+Starting with libpng-1.6.0, the library included a "simplified API".
+This requires setjmp/longjmp, so you must either build the library
+with PNG_SETJMP_SUPPORTED defined, or with PNG_SIMPLIFIED_READ_SUPPORTED
+and PNG_SIMPLIFIED_WRITE_SUPPORTED undefined.
+
+XVI. Other sources of information about libpng:
+
 Further information can be found in the README and libpng-manual.txt
 files, in the individual makefiles, in png.h, and the manual pages
 libpng.3 and png.5.
@@ -147,7 +399,7 @@ CFLAGS="-Wall -O -funroll-loops \
 --with-pkgconfigdir=/usr/lib/pkgconfig --includedir=/usr/include
 
 You can alternatively specify --includedir=/usr/include, /usr/local/include,
-/usr/include/libpng%NN%, or whatever.
+/usr/include/libpng16, or whatever.
 
 If you find that the configure script is out-of-date or is not supporting
 your platform properly, try running autogen.sh to regenerate "configure",
diff --git a/src/3rdparty/libpng/LICENSE b/src/3rdparty/libpng/LICENSE
index b72d125..eb4a9a9 100644
--- a/src/3rdparty/libpng/LICENSE
+++ b/src/3rdparty/libpng/LICENSE
@@ -10,8 +10,8 @@ this sentence.
 
 This code is released under the libpng license.
 
-libpng versions 1.2.6, August 15, 2004, through 1.5.10, March 29, 2012, are
-Copyright (c) 2004, 2006-2011 Glenn Randers-Pehrson, and are
+libpng versions 1.2.6, August 15, 2004, through 1.6.17, March 26, 2015, are
+Copyright (c) 2004, 2006-2015 Glenn Randers-Pehrson, and are
 distributed according to the same disclaimer and license as libpng-1.2.5
 with the following individual added to the list of Contributing Authors
 
@@ -108,4 +108,4 @@ certification mark of the Open Source Initiative.
 
 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-March 29, 2012
+March 26, 2015
diff --git a/src/3rdparty/libpng/README b/src/3rdparty/libpng/README
index e821ee4..a158ea8 100644
--- a/src/3rdparty/libpng/README
+++ b/src/3rdparty/libpng/README
@@ -1,11 +1,11 @@
-README for libpng version 1.5.10 - March 29, 2012 (shared library 15.0)
+README for libpng version 1.6.17 - March 26, 2015 (shared library 16.0)
 See the note about version numbers near the top of png.h
 
 See INSTALL for instructions on how to install libpng.
 
-Libpng comes in several distribution formats.  Get libpng-*.tar.gz,
-libpng-*.tar.xz or libpng-*.tar.bz2 if you want UNIX-style line endings
-in the text files, or lpng*.zip if you want DOS-style line endings.
+Libpng comes in several distribution formats.  Get libpng-*.tar.gz or
+libpng-*.tar.xz or if you want UNIX-style line endings in the text files,
+or lpng*.7z or lpng*.zip if you want DOS-style line endings.
 
 Version 0.89 was the first official release of libpng.  Don't let the
 fact that it's the first release fool you.  The libpng library has been in
@@ -23,18 +23,25 @@ earlier versions if you are using a shared library.  The type of the
 png_uint_32, which will affect shared-library applications that use
 this function.
 
-To avoid problems with changes to the internals of png_info_struct,
+To avoid problems with changes to the internals of png info_struct,
 new APIs have been made available in 0.95 to avoid direct application
 access to info_ptr.  These functions are the png_set_<chunk> and
 png_get_<chunk> functions.  These functions should be used when
 accessing/storing the info_struct data, rather than manipulating it
 directly, to avoid such problems in the future.
 
-It is important to note that the APIs do not make current programs
+It is important to note that the APIs did not make current programs
 that access the info struct directly incompatible with the new
-library.  However, it is strongly suggested that new programs use
-the new APIs (as shown in example.c and pngtest.c), and older programs
-be converted to the new format, to facilitate upgrades in the future.
+library, through libpng-1.2.x.  In libpng-1.4.x, which was meant to
+be a transitional release, members of the png_struct and the
+info_struct can still be accessed, but the compiler will issue a
+warning about deprecated usage.  Since libpng-1.5.0, direct access
+to these structs is not allowed, and the definitions of the structs
+reside in private pngstruct.h and pnginfo.h header files that are not
+accessible to applications.  It is strongly suggested that new
+programs use the new APIs (as shown in example.c and pngtest.c), and
+older programs be converted to the new format, to facilitate upgrades
+in the future.
 ****
 
 Additions since 0.90 include the ability to compile libpng as a
@@ -77,17 +84,21 @@ compression library that is useful for more things than just PNG files.
 You can use zlib as a drop-in replacement for fread() and fwrite() if
 you are so inclined.
 
-zlib should be available at the same place that libpng is, or at.
-ftp://ftp.info-zip.org/pub/infozip/zlib
+zlib should be available at the same place that libpng is, or at zlib.net.
 
 You may also want a copy of the PNG specification.  It is available
 as an RFC, a W3C Recommendation, and an ISO/IEC Standard.  You can find
 these at http://www.libpng.org/pub/png/documents/
 
 This code is currently being archived at libpng.sf.net in the
-[DOWNLOAD] area, and on CompuServe, Lib 20 (PNG SUPPORT)
-at GO GRAPHSUP.  If you can't find it in any of those places,
-e-mail me, and I'll help you find it.
+[DOWNLOAD] area, and at ftp://ftp.simplesystems.org.  If you can't find it
+in any of those places, e-mail me, and I'll help you find it.
+
+I am not a lawyer, but I believe that the Export Control Classification
+Number (ECCN) for libpng is EAR99, which means not subject to export
+controls or International Traffic in Arms Regulations (ITAR) because it
+is open source, publicly available software, that does not contain any
+encryption software.  See the EAR, paragraphs 734.3(b)(3) and 734.7(b).
 
 If you have any code changes, requests, problems, etc., please e-mail
 them to me.  Also, I'd appreciate any make files or project files,
@@ -105,7 +116,7 @@ based in a large way on Guy's and Andreas' earlier work), and the PNG
 development group.
 
 Send comments/corrections/commendations to png-mng-implement at
-lists.sourceforge.net (subscription required; visit 
+lists.sourceforge.net (subscription required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-implement
 to subscribe) or to glennrp at users.sourceforge.net
 
@@ -123,7 +134,7 @@ and ...".  If in doubt, send questions to me.  I'll bounce them
 to others, if necessary.
 
 Please do not send suggestions on how to change PNG.  We have
-been discussing PNG for sixteen years now, and it is official and
+been discussing PNG for nineteen years now, and it is official and
 finished.  If you have suggestions for libpng, however, I'll
 gladly listen.  Even if your suggestion is not used immediately,
 it may be used later.
@@ -167,23 +178,25 @@ Files in this distribution:
       pngwrite.c    =>  High-level write functions
       pngwtran.c    =>  Write data transformations
       pngwutil.c    =>  Write utility functions
+      arm           =>  Contains optimized code for the ARM platform
       contrib       =>  Contributions
+       examples         =>  Example programs
        gregbook         =>  source code for PNG reading and writing, from
                             Greg Roelofs' "PNG: The Definitive Guide",
                             O'Reilly, 1999
-       msvctest     =>  Builds and runs pngtest using a MSVC workspace
-       pngminus     =>  Simple pnm2png and png2pnm programs
-       pngsuite     =>  Test images
-       visupng      =>  Contains a MSVC workspace for VisualPng
+       libtests         =>  Test programs
+       pngminim         =>  Minimal decoder, encoder, and progressive decoder
+                            programs demonstrating use of pngusr.dfa
+       pngminus         =>  Simple pnm2png and png2pnm programs
+       pngsuite         =>  Test images
+       tools            =>  Various tools
+       visupng          =>  Contains a MSVC workspace for VisualPng
       projects      =>  Contains project files and workspaces for
                         building a DLL
-       cbuilder5        =>  Contains a Borland workspace for building
-                            libpng and zlib
-       visualc6         =>  Contains a Microsoft Visual C++ (MSVC)
-                            workspace for building libpng and zlib
+       owatcom          =>  Contains a WATCOM project for building libpng
        visualc71        =>  Contains a Microsoft Visual C++ (MSVC)
                             workspace for building libpng and zlib
-       xcode            =>  Contains an Apple xcode
+       vstudio          =>  Contains a Microsoft Visual C++ (MSVC)
                             workspace for building libpng and zlib
       scripts       =>  Directory containing scripts for building libpng:
                             (see scripts/README.txt for the list of scripts)
diff --git a/src/3rdparty/libpng/libpng-manual.txt b/src/3rdparty/libpng/libpng-manual.txt
index d55e80a..f0dae98 100644
--- a/src/3rdparty/libpng/libpng-manual.txt
+++ b/src/3rdparty/libpng/libpng-manual.txt
@@ -1,9 +1,9 @@
 libpng-manual.txt - A description on how to use and modify libpng
 
- libpng version 1.5.10 - March 29, 2012
+ libpng version 1.6.17 - March 26, 2015
  Updated and distributed by Glenn Randers-Pehrson
  <glennrp at users.sourceforge.net>
- Copyright (c) 1998-2011 Glenn Randers-Pehrson
+ Copyright (c) 1998-2015 Glenn Randers-Pehrson
 
  This document is released under the libpng license.
  For conditions of distribution and use, see the disclaimer
@@ -11,15 +11,15 @@ libpng-manual.txt - A description on how to use and modify libpng
 
  Based on:
 
- libpng versions 0.97, January 1998, through 1.5.10 - March 29, 2012
+ libpng versions 0.97, January 1998, through 1.6.17 - March 26, 2015
  Updated and distributed by Glenn Randers-Pehrson
- Copyright (c) 1998-2011 Glenn Randers-Pehrson
+ Copyright (c) 1998-2015 Glenn Randers-Pehrson
 
- libpng 1.0 beta 6  version 0.96 May 28, 1997
+ libpng 1.0 beta 6 - version 0.96 - May 28, 1997
  Updated and distributed by Andreas Dilger
  Copyright (c) 1996, 1997 Andreas Dilger
 
- libpng 1.0 beta 2 - version 0.88  January 26, 1996
+ libpng 1.0 beta 2 - version 0.88 - January 26, 1996
  For conditions of distribution and use, see copyright
  notice in png.h. Copyright (c) 1995, 1996 Guy Eric
  Schalnat, Group 42, Inc.
@@ -28,16 +28,33 @@ libpng-manual.txt - A description on how to use and modify libpng
  Copyright (c) 1995, 1996 Frank J. T. Wojcik
  December 18, 1995 & January 20, 1996
 
+ TABLE OF CONTENTS
+
+    I. Introduction
+   II. Structures
+  III. Reading
+   IV. Writing
+    V. Simplified API
+   VI. Modifying/Customizing libpng
+  VII. MNG support
+ VIII. Changes to Libpng from version 0.88
+   IX. Changes to Libpng from version 1.0.x to 1.2.x
+    X. Changes to Libpng from version 1.0.x/1.2.x to 1.4.x
+   XI. Changes to Libpng from version 1.4.x to 1.5.x
+  XII. Changes to Libpng from version 1.5.x to 1.6.x
+ XIII. Detecting libpng
+  XIV. Source code repository
+   XV. Coding style
+  XVI. Y2K Compliance in libpng
+
 I. Introduction
 
 This file describes how to use and modify the PNG reference library
-(known as libpng) for your own use.  There are five sections to this
-file: introduction, structures, reading, writing, and modification and
-configuration notes for various special platforms.  In addition to this
+(known as libpng) for your own use.  In addition to this
 file, example.c is a good starting point for using the library, as
 it is heavily commented and should include everything most people
 will need.  We assume that libpng is already installed; see the
-INSTALL file for instructions on how to install libpng.
+INSTALL file for instructions on how to configure and install libpng.
 
 For examples of libpng usage, see the files "example.c", "pngtest.c",
 and the files in the "contrib" directory, all of which are included in
@@ -48,7 +65,7 @@ of reducing the amount of time and effort it takes to support the PNG
 file format in application programs.
 
 The PNG specification (second edition), November 2003, is available as
-a W3C Recommendation and as an ISO Standard (ISO/IEC 15948:2003 (E)) at
+a W3C Recommendation and as an ISO Standard (ISO/IEC 15948:2004 (E)) at
 <http://www.w3.org/TR/2003/REC-PNG-20031110/
 The W3C and ISO documents have identical technical content.
 
@@ -141,8 +158,8 @@ APIs.  Most of these are fairly obvious; for example types corresponding
 to integers of particular sizes and types for passing color values.
 
 One exception is how non-integral numbers are handled.  For application
-convenience most APIs that take such numbers have C (double) arguments,
-however internally PNG, and libpng, use 32 bit signed integers and encode
+convenience most APIs that take such numbers have C (double) arguments;
+however, internally PNG, and libpng, use 32 bit signed integers and encode
 the value by multiplying by 100,000.  As of libpng 1.5.0 a convenience
 macro PNG_FP_1 is defined in png.h along with a type (png_fixed_point)
 which is simply (png_int_32).
@@ -257,10 +274,10 @@ This method of building a customized pnglibconf.h is illustrated in
 contrib/pngminim/*.  See the "$(PNGCONF):" target in the makefile and
 pngusr.dfa in these directories.
 
-C. Configuration using PNG_USR_CONFIG
+C. Configuration using PNG_USER_CONFIG
 
-If -DPNG_USR_CONFIG is added to the CFLAGS when pnglibconf.h is built the file
-pngusr.h will automatically be included before the options in
+If -DPNG_USER_CONFIG is added to the CPPFLAGS when pnglibconf.h is built,
+the file pngusr.h will automatically be included before the options in
 scripts/pnglibconf.dfa are processed.  Your pngusr.h file should contain only
 macro definitions turning features on or off or setting settings.
 
@@ -319,7 +336,7 @@ prediction.
 
 If you are intending to keep the file pointer open for use in libpng,
 you must ensure you don't read more than 8 bytes from the beginning
-of the file, and you also have to make a call to png_set_sig_bytes_read()
+of the file, and you also have to make a call to png_set_sig_bytes()
 with the number of bytes you read from the beginning.  Libpng will
 then only check the bytes (if any) that your program didn't read.
 
@@ -327,22 +344,23 @@ then only check the bytes (if any) that your program didn't read.
 to replace them with custom functions.  See the discussion under
 Customizing libpng.
 
-
     FILE *fp = fopen(file_name, "rb");
     if (!fp)
     {
        return (ERROR);
     }
 
-    fread(header, 1, number, fp);
-    is_png = !png_sig_cmp(header, 0, number);
+    if (fread(header, 1, number, fp) != number)
+    {
+       return (ERROR);
+    }
 
+    is_png = !png_sig_cmp(header, 0, number);
     if (!is_png)
     {
        return (NOT_PNG);
     }
 
-
 Next, png_struct and png_info need to be allocated and initialized.  In
 order to ensure that the size of these structures is correct even with a
 dynamically linked libpng, there are functions to initialize and
@@ -508,9 +526,14 @@ you can retrieve with
     png_get_user_chunk_ptr(png_ptr);
 
 If you call the png_set_read_user_chunk_fn() function, then all unknown
-chunks will be saved when read, in case your callback function will need
-one or more of them.  This behavior can be changed with the
-png_set_keep_unknown_chunks() function, described below.
+chunks which the callback does not handle will be saved when read.  You can
+cause them to be discarded by returning '1' ("handled") instead of '0'.  This
+behavior will change in libpng 1.7 and the default handling set by the
+png_set_keep_unknown_chunks() function, described below, will be used when the
+callback returns 0.  If you want the existing behavior you should set the global
+default to PNG_HANDLE_CHUNK_IF_SAFE now; this is compatible with all current
+versions of libpng and with 1.7.  Libpng 1.6 issues a warning if you keep the
+default, or PNG_HANDLE_CHUNK_NEVER, and the callback returns 0.
 
 At this point, you can set up a callback function that will be
 called after each row has been read, which you can use to control
@@ -553,6 +576,7 @@ chunk types. To change this, you can call:
 
     png_set_keep_unknown_chunks(png_ptr, keep,
         chunk_list, num_chunks);
+
     keep       - 0: default unknown chunk handling
                  1: ignore; do not keep
                  2: keep only if safe-to-copy
@@ -566,11 +590,16 @@ chunk types. To change this, you can call:
 
     chunk_list - list of chunks affected (a byte string,
                  five bytes per chunk, NULL or '\0' if
-                 num_chunks is 0)
+                 num_chunks is positive; ignored if
+                 numchunks <= 0).
 
     num_chunks - number of chunks affected; if 0, all
-                 unknown chunks are affected.  If nonzero,
-                 only the chunks in the list are affected
+                 unknown chunks are affected.  If positive,
+                 only the chunks in the list are affected,
+                 and if negative all unknown chunks and
+                 all known chunks except for the IHDR,
+                 PLTE, tRNS, IDAT, and IEND chunks are
+                 affected.
 
 Unknown chunks declared in this way will be saved as raw data onto a
 list of png_unknown_chunk structures.  If a chunk that is normally
@@ -603,30 +632,29 @@ callback function:
     ...
 
     #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
-      /* ignore all unknown chunks: */
-      png_set_keep_unknown_chunks(read_ptr, 1, NULL, 0);
+      /* ignore all unknown chunks
+       * (use global setting "2" for libpng16 and earlier):
+       */
+      png_set_keep_unknown_chunks(read_ptr, 2, NULL, 0);
 
       /* except for vpAg: */
       png_set_keep_unknown_chunks(read_ptr, 2, vpAg, 1);
 
       /* also ignore unused known chunks: */
       png_set_keep_unknown_chunks(read_ptr, 1, unused_chunks,
-         (int)sizeof(unused_chunks)/5);
+         (int)(sizeof unused_chunks)/5);
     #endif
 
 User limits
 
 The PNG specification allows the width and height of an image to be as
 large as 2^31-1 (0x7fffffff), or about 2.147 billion rows and columns.
-Since very few applications really need to process such large images,
-we have imposed an arbitrary 1-million limit on rows and columns.
 Larger images will be rejected immediately with a png_error() call. If
-you wish to change this limit, you can use
+you wish to change these limits, you can use
 
    png_set_user_limits(png_ptr, width_max, height_max);
 
-to set your own limits, or use width_max = height_max = 0x7fffffffL
-to allow all valid dimensions (libpng may reject some very large images
+to set your own limits (libpng may reject some very wide images
 anyway because of potential buffer overflow conditions).
 
 You should put this statement after you create the PNG structure and
@@ -650,9 +678,6 @@ where 0x7fffffffL means unlimited.  You can retrieve this limit with
 
    chunk_cache_max = png_get_chunk_cache_max(png_ptr);
 
-This limit also applies to the number of buffers that can be allocated
-by png_decompress_chunk() while decompressing iTXt, zTXt, and iCCP chunks.
-
 You can also set a limit on the amount of memory that a compressed chunk
 other than IDAT can occupy, with
 
@@ -685,11 +710,12 @@ value.  You can also specify a default encoding for the PNG file in
 case the required information is missing from the file.  By default libpng
 assumes that the PNG data matches your system, to keep this default call:
 
-   png_set_gamma(png_ptr, screen_gamma, 1/screen_gamma/*file gamma*/);
+   png_set_gamma(png_ptr, screen_gamma, output_gamma);
 
 or you can use the fixed point equivalent:
 
-   png_set_gamma_fixed(png_ptr, PNG_FP_1*screen_gamma, PNG_FP_1/screen_gamma);
+   png_set_gamma_fixed(png_ptr, PNG_FP_1*screen_gamma,
+      PNG_FP_1*output_gamma);
 
 If you don't know the gamma for your system it is probably 2.2 - a good
 approximation to the IEC standard for display systems (sRGB).  If images are
@@ -701,19 +727,86 @@ display driver, a few systems, including older Macs, change the response by
 default.  As of 1.5.4 three special values are available to handle common
 situations:
 
-   PNG_DEFAULT_sRGB: Indicates that the system conforms to the IEC 61966-2-1
-                     standard.  This matches almost all systems.
-   PNG_GAMMA_MAC_18: Indicates that the system is an older (pre Mac OS 10.6)
-                     Apple Macintosh system with the default settings.
-   PNG_GAMMA_LINEAR: Just the fixed point value for 1.0 - indicates that the
-                     system expects data with no gamma encoding.
+   PNG_DEFAULT_sRGB: Indicates that the system conforms to the
+                     IEC 61966-2-1 standard.  This matches almost
+                     all systems.
+   PNG_GAMMA_MAC_18: Indicates that the system is an older
+                     (pre Mac OS 10.6) Apple Macintosh system with
+                     the default settings.
+   PNG_GAMMA_LINEAR: Just the fixed point value for 1.0 - indicates
+                     that the system expects data with no gamma
+                     encoding.
 
 You would use the linear (unencoded) value if you need to process the pixel
-values further because this avoids the need to decode and reencode each
+values further because this avoids the need to decode and re-encode each
 component value whenever arithmetic is performed.  A lot of graphics software
 uses linear values for this reason, often with higher precision component values
 to preserve overall accuracy.
 
+
+The output_gamma value expresses how to decode the output values, not how
+they are encoded.  The values used correspond to the normal numbers used to
+describe the overall gamma of a computer display system; for example 2.2 for
+an sRGB conformant system.  The values are scaled by 100000 in the _fixed
+version of the API (so 220000 for sRGB.)
+
+The inverse of the value is always used to provide a default for the PNG file
+encoding if it has no gAMA chunk and if png_set_gamma() has not been called
+to override the PNG gamma information.
+
+When the ALPHA_OPTIMIZED mode is selected the output gamma is used to encode
+opaque pixels however pixels with lower alpha values are not encoded,
+regardless of the output gamma setting.
+
+When the standard Porter Duff handling is requested with mode 1 the output
+encoding is set to be linear and the output_gamma value is only relevant
+as a default for input data that has no gamma information.  The linear output
+encoding will be overridden if png_set_gamma() is called - the results may be
+highly unexpected!
+
+The following numbers are derived from the sRGB standard and the research
+behind it.  sRGB is defined to be approximated by a PNG gAMA chunk value of
+0.45455 (1/2.2) for PNG.  The value implicitly includes any viewing
+correction required to take account of any differences in the color
+environment of the original scene and the intended display environment; the
+value expresses how to *decode* the image for display, not how the original
+data was *encoded*.
+
+sRGB provides a peg for the PNG standard by defining a viewing environment.
+sRGB itself, and earlier TV standards, actually use a more complex transform
+(a linear portion then a gamma 2.4 power law) than PNG can express.  (PNG is
+limited to simple power laws.)  By saying that an image for direct display on
+an sRGB conformant system should be stored with a gAMA chunk value of 45455
+(11.3.3.2 and 11.3.3.5 of the ISO PNG specification) the PNG specification
+makes it possible to derive values for other display systems and
+environments.
+
+The Mac value is deduced from the sRGB based on an assumption that the actual
+extra viewing correction used in early Mac display systems was implemented as
+a power 1.45 lookup table.
+
+Any system where a programmable lookup table is used or where the behavior of
+the final display device characteristics can be changed requires system
+specific code to obtain the current characteristic.  However this can be
+difficult and most PNG gamma correction only requires an approximate value.
+
+By default, if png_set_alpha_mode() is not called, libpng assumes that all
+values are unencoded, linear, values and that the output device also has a
+linear characteristic.  This is only very rarely correct - it is invariably
+better to call png_set_alpha_mode() with PNG_DEFAULT_sRGB than rely on the
+default if you don't know what the right answer is!
+
+The special value PNG_GAMMA_MAC_18 indicates an older Mac system (pre Mac OS
+10.6) which used a correction table to implement a somewhat lower gamma on an
+otherwise sRGB system.
+
+Both these values are reserved (not simple gamma values) in order to allow
+more precise correction internally in the future.
+
+NOTE: the values can be passed to either the fixed or floating
+point APIs, but the floating point API will also accept floating point
+values.
+
 The second thing you may need to tell libpng about is how your system handles
 alpha channel information.  Some, but not all, PNG files contain an alpha
 channel.  To display these files correctly you need to compose the data onto a
@@ -723,11 +816,11 @@ Libpng only supports composing onto a single color (using png_set_background;
 see below).  Otherwise you must do the composition yourself and, in this case,
 you may need to call png_set_alpha_mode:
 
-#if PNG_LIBPNG_VER >= 10504
-   png_set_alpha_mode(png_ptr, mode, screen_gamma);
-#else
-   png_set_gamma(png_ptr, screen_gamma, 1.0/screen_gamma);
-#endif
+   #if PNG_LIBPNG_VER >= 10504
+      png_set_alpha_mode(png_ptr, mode, screen_gamma);
+   #else
+      png_set_gamma(png_ptr, screen_gamma, 1.0/screen_gamma);
+   #endif
 
 The screen_gamma value is the same as the argument to png_set_gamma; however,
 how it affects the output depends on the mode.  png_set_alpha_mode() sets the
@@ -738,11 +831,11 @@ by png_set_alpha_mode().
 
 The mode is as follows:
 
-    PNG_ALPHA_PNG: The data is encoded according to the PNG specification.  Red,
-green and blue, or gray, components are gamma encoded color
-values and are not premultiplied by the alpha value.  The
-alpha value is a linear measure of the contribution of the
-pixel to the corresponding final output pixel.
+    PNG_ALPHA_PNG: The data is encoded according to the PNG
+specification.  Red, green and blue, or gray, components are
+gamma encoded color values and are not premultiplied by the
+alpha value.  The alpha value is a linear measure of the
+contribution of the pixel to the corresponding final output pixel.
 
 You should normally use this format if you intend to perform
 color correction on the color values; most, maybe all, color
@@ -759,11 +852,35 @@ be used!
 
 The remaining modes assume you don't need to do any further color correction or
 that if you do, your color correction software knows all about alpha (it
-probably doesn't!)
-
-    PNG_ALPHA_STANDARD:  The data libpng produces
-is encoded in the standard way
-assumed by most correctly written graphics software.
+probably doesn't!).  They 'associate' the alpha with the color information by
+storing color channel values that have been scaled by the alpha.  The
+advantage is that the color channels can be resampled (the image can be
+scaled) in this form.  The disadvantage is that normal practice is to store
+linear, not (gamma) encoded, values and this requires 16-bit channels for
+still images rather than the 8-bit channels that are just about sufficient if
+gamma encoding is used.  In addition all non-transparent pixel values,
+including completely opaque ones, must be gamma encoded to produce the final
+image.  These are the 'STANDARD', 'ASSOCIATED' or 'PREMULTIPLIED' modes
+described below (the latter being the two common names for associated alpha
+color channels). Note that PNG files always contain non-associated color
+channels; png_set_alpha_mode() with one of the modes causes the decoder to
+convert the pixels to an associated form before returning them to your
+application. 
+
+Since it is not necessary to perform arithmetic on opaque color values so
+long as they are not to be resampled and are in the final color space it is
+possible to optimize the handling of alpha by storing the opaque pixels in
+the PNG format (adjusted for the output color space) while storing partially
+opaque pixels in the standard, linear, format.  The accuracy required for
+standard alpha composition is relatively low, because the pixels are
+isolated, therefore typically the accuracy loss in storing 8-bit linear
+values is acceptable.  (This is not true if the alpha channel is used to
+simulate transparency over large areas - use 16 bits or the PNG mode in
+this case!)  This is the 'OPTIMIZED' mode.  For this mode a pixel is
+treated as opaque only if the alpha value is equal to the maximum value.
+
+    PNG_ALPHA_STANDARD:  The data libpng produces is encoded in the
+standard way assumed by most correctly written graphics software.
 The gamma encoding will be removed by libpng and the
 linear component values will be pre-multiplied by the
 alpha channel.
@@ -792,14 +909,13 @@ dynamic range.  To avoid problems, and if your software
 supports it, use png_set_expand_16() to force all
 components to 16 bits.
 
-    PNG_ALPHA_OPTIMIZED: This mode is the same
-as PNG_ALPHA_STANDARD except that
-completely opaque pixels are gamma encoded according to
+    PNG_ALPHA_OPTIMIZED: This mode is the same as PNG_ALPHA_STANDARD
+except that completely opaque pixels are gamma encoded according to
 the screen_gamma value.  Pixels with alpha less than 1.0
 will still have linear components.
 
 Use this format if you have control over your
-compositing software and do don't do other arithmetic
+compositing software and so don't do other arithmetic
 (such as scaling) on the data you get from libpng.  Your
 compositing software can simply copy opaque pixels to
 the output but still has linear values for the
@@ -813,18 +929,16 @@ representation of non-opaque pixels are irrelevant.
 You can also try this format if your software is broken;
 it might look better.
 
-    PNG_ALPHA_BROKEN: This is PNG_ALPHA_STANDARD;
-however, all component values,
-including the alpha channel are gamma encoded.  This is
-an appropriate format to try if your software, or more
-likely hardware, is totally broken, i.e., if it performs
-linear arithmetic directly on gamma encoded values.
-
-In most cases of broken software or hardware the bug in the final display
-manifests as a subtle halo around composited parts of the image.  You may not
-even perceive this as a halo; the composited part of the image may simply appear
-separate from the background, as though it had been cut out of paper and pasted
-on afterward.
+    PNG_ALPHA_BROKEN: This is PNG_ALPHA_STANDARD; however, all component
+values, including the alpha channel are gamma encoded.  This is
+broken because, in practice, no implementation that uses this choice
+correctly undoes the encoding before handling alpha composition.  Use this
+choice only if other serious errors in the software or hardware you use
+mandate it.  In most cases of broken software or hardware the bug in the
+final display manifests as a subtle halo around composited parts of the
+image.  You may not even perceive this as a halo; the composited part of
+the image may simply appear separate from the background, as though it had
+been cut out of paper and pasted on afterward.
 
 If you don't have to deal with bugs in software or hardware, or if you can fix
 them, there are three recommended ways of using png_set_alpha_mode():
@@ -855,6 +969,89 @@ All you can do is compose the result onto a matching output.  Since this
 mode is libpng-specific you also need to write your own composition
 software.
 
+The following are examples of calls to png_set_alpha_mode to achieve the
+required overall gamma correction and, where necessary, alpha
+premultiplication.
+
+    png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
+
+This is the default libpng handling of the alpha channel - it is not
+pre-multiplied into the color components.  In addition the call states
+that the output is for a sRGB system and causes all PNG files without gAMA
+chunks to be assumed to be encoded using sRGB.
+
+    png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
+
+In this case the output is assumed to be something like an sRGB conformant
+display preceeded by a power-law lookup table of power 1.45.  This is how
+early Mac systems behaved.
+
+    png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_GAMMA_LINEAR);
+
+This is the classic Jim Blinn approach and will work in academic
+environments where everything is done by the book.  It has the shortcoming
+of assuming that input PNG data with no gamma information is linear - this
+is unlikely to be correct unless the PNG files where generated locally.
+Most of the time the output precision will be so low as to show
+significant banding in dark areas of the image.
+
+    png_set_expand_16(pp);
+    png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_DEFAULT_sRGB);
+
+This is a somewhat more realistic Jim Blinn inspired approach.  PNG files
+are assumed to have the sRGB encoding if not marked with a gamma value and
+the output is always 16 bits per component.  This permits accurate scaling
+and processing of the data.  If you know that your input PNG files were
+generated locally you might need to replace PNG_DEFAULT_sRGB with the
+correct value for your system.
+
+    png_set_alpha_mode(pp, PNG_ALPHA_OPTIMIZED, PNG_DEFAULT_sRGB);
+
+If you just need to composite the PNG image onto an existing background
+and if you control the code that does this you can use the optimization
+setting.  In this case you just copy completely opaque pixels to the
+output.  For pixels that are not completely transparent (you just skip
+those) you do the composition math using png_composite or png_composite_16
+below then encode the resultant 8-bit or 16-bit values to match the output
+encoding.
+
+    Other cases
+
+If neither the PNG nor the standard linear encoding work for you because
+of the software or hardware you use then you have a big problem.  The PNG
+case will probably result in halos around the image.  The linear encoding
+will probably result in a washed out, too bright, image (it's actually too
+contrasty.)  Try the ALPHA_OPTIMIZED mode above - this will probably
+substantially reduce the halos.  Alternatively try:
+
+    png_set_alpha_mode(pp, PNG_ALPHA_BROKEN, PNG_DEFAULT_sRGB);
+
+This option will also reduce the halos, but there will be slight dark
+halos round the opaque parts of the image where the background is light.
+In the OPTIMIZED mode the halos will be light halos where the background
+is dark.  Take your pick - the halos are unavoidable unless you can get
+your hardware/software fixed!  (The OPTIMIZED approach is slightly
+faster.)
+
+When the default gamma of PNG files doesn't match the output gamma.
+If you have PNG files with no gamma information png_set_alpha_mode allows
+you to provide a default gamma, but it also sets the ouput gamma to the
+matching value.  If you know your PNG files have a gamma that doesn't
+match the output you can take advantage of the fact that
+png_set_alpha_mode always sets the output gamma but only sets the PNG
+default if it is not already set:
+
+    png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
+    png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
+
+The first call sets both the default and the output gamma values, the
+second call overrides the output gamma without changing the default.  This
+is easier than achieving the same effect with png_set_gamma.  You must use
+PNG_ALPHA_PNG for the first call - internal checking in png_set_alpha will
+fire if more than one call to png_set_alpha_mode and png_set_background is
+made in the same read operation, however multiple calls with PNG_ALPHA_PNG
+are ignored.
+
 If you don't need, or can't handle, the alpha channel you can call
 png_set_background() to remove it by compositing against a fixed color.  Don't
 call png_set_strip_alpha() to do this - it will leave spurious pixel values in
@@ -962,7 +1159,7 @@ where row_pointers is an array of pointers to the pixel data for each row:
 If you know your image size and pixel size ahead of time, you can allocate
 row_pointers prior to calling png_read_png() with
 
-   if (height > PNG_UINT_32_MAX/png_sizeof(png_byte))
+   if (height > PNG_UINT_32_MAX/(sizeof (png_byte)))
       png_error (png_ptr,
           "Image is too tall to process in memory");
 
@@ -971,7 +1168,7 @@ row_pointers prior to calling png_read_png() with
           "Image is too wide to process in memory");
 
    row_pointers = png_malloc(png_ptr,
-       height*png_sizeof(png_bytep));
+       height*(sizeof (png_bytep)));
 
    for (int i=0; i<height, i++)
       row_pointers[i]=NULL;  /* security precaution */
@@ -1068,13 +1265,13 @@ in until png_read_end() has read the chunk data following the image.
                      the PNG datastream is embedded in
                      a MNG-1.0 datastream)
 
-    Any or all of interlace_type, compression_type, or
-    filter_method can be NULL if you are
-    not interested in their values.
+    Any of width, height, color_type, bit_depth,
+    interlace_type, compression_type, or filter_method can
+    be NULL if you are not interested in their values.
 
     Note that png_get_IHDR() returns 32-bit data into
     the application's width and height variables.
-    This is an unsafe situation if these are 16-bit
+    This is an unsafe situation if these are not png_uint_32
     variables.  In such situations, the
     png_get_image_width() and png_get_image_height()
     functions described below are safer.
@@ -1130,6 +1327,15 @@ data has been read, or zero if it is missing.  The parameters to the
 png_get_<chunk> are set directly if they are simple data types, or a
 pointer into the info_ptr is returned for any complex types.
 
+The colorspace data from gAMA, cHRM, sRGB, iCCP, and sBIT chunks
+is simply returned to give the application information about how the
+image was encoded.  Libpng itself only does transformations using the file
+gamma when combining semitransparent pixels with the background color, and,
+since libpng-1.6.0, when converting between 8-bit sRGB and 16-bit linear pixels
+within the simplified API.  Libpng also uses the file gamma when converting
+RGB to gray, beginning with libpng-1.0.5, if the application calls
+png_set_rgb_to_gray()).
+
     png_get_PLTE(png_ptr, info_ptr, &palette,
                      &num_palette);
 
@@ -1147,31 +1353,36 @@ pointer into the info_ptr is returned for any complex types.
     int_file_gamma - 100,000 times the gamma at which the
                      file is written
 
-    png_get_cHRM(png_ptr, info_ptr,  &white_x, &white_y, &red_x, &red_y,
-                     &green_x, &green_y, &blue_x, &blue_y)
-    png_get_cHRM_XYZ(png_ptr, info_ptr, &red_X, &red_Y, &red_Z, &green_X,
-                     &green_Y, &green_Z, &blue_X, &blue_Y, &blue_Z)
-    png_get_cHRM_fixed(png_ptr, info_ptr, &int_white_x, &int_white_y,
-                     &int_red_x, &int_red_y, &int_green_x, &int_green_y,
-                     &int_blue_x, &int_blue_y)
+    png_get_cHRM(png_ptr, info_ptr,  &white_x, &white_y, &red_x,
+                     &red_y, &green_x, &green_y, &blue_x, &blue_y)
+    png_get_cHRM_XYZ(png_ptr, info_ptr, &red_X, &red_Y, &red_Z,
+                     &green_X, &green_Y, &green_Z, &blue_X, &blue_Y,
+                     &blue_Z)
+    png_get_cHRM_fixed(png_ptr, info_ptr, &int_white_x,
+                     &int_white_y, &int_red_x, &int_red_y,
+                     &int_green_x, &int_green_y, &int_blue_x,
+                     &int_blue_y)
     png_get_cHRM_XYZ_fixed(png_ptr, info_ptr, &int_red_X, &int_red_Y,
-                     &int_red_Z, &int_green_X, &int_green_Y, &int_green_Z,
-                     &int_blue_X, &int_blue_Y, &int_blue_Z)
+                     &int_red_Z, &int_green_X, &int_green_Y,
+                     &int_green_Z, &int_blue_X, &int_blue_Y,
+                     &int_blue_Z)
 
     {white,red,green,blue}_{x,y}
-                     A color space encoding specified using the chromaticities
-                     of the end points and the white point. (PNG_INFO_cHRM)
+                     A color space encoding specified using the
+                     chromaticities of the end points and the
+                     white point. (PNG_INFO_cHRM)
 
     {red,green,blue}_{X,Y,Z}
-                     A color space encoding specified using the encoding end
-                     points - the CIE tristimulus specification of the intended
-                     color of the red, green and blue channels in the PNG RGB
-                     data.  The white point is simply the sum of the three end
-                     points. (PNG_INFO_cHRM)
+                     A color space encoding specified using the
+                     encoding end points - the CIE tristimulus
+                     specification of the intended color of the red,
+                     green and blue channels in the PNG RGB data.
+                     The white point is simply the sum of the three
+                     end points. (PNG_INFO_cHRM)
 
     png_get_sRGB(png_ptr, info_ptr, &srgb_intent);
 
-    file_srgb_intent - the rendering intent (PNG_INFO_sRGB)
+    srgb_intent -    the rendering intent (PNG_INFO_sRGB)
                      The presence of the sRGB chunk
                      means that the pixel data is in the
                      sRGB color space.  This chunk also
@@ -1571,17 +1782,19 @@ Within the matrix,
      "A" means the transformation is obtained by png_set_add_alpha().
      "X" means the transformation is obtained by png_set_expand().
      "1" means the transformation is obtained by
-         png_set_expand_gray_1_2_4_to_8() (and by png_set_expand() if there
-         is no transparency in the original or the final format).
+         png_set_expand_gray_1_2_4_to_8() (and by png_set_expand()
+         if there is no transparency in the original or the final
+         format).
      "C" means the transformation is obtained by png_set_gray_to_rgb().
      "G" means the transformation is obtained by png_set_rgb_to_gray().
      "P" means the transformation is obtained by
          png_set_expand_palette_to_rgb().
      "p" means the transformation is obtained by png_set_packing().
      "Q" means the transformation is obtained by png_set_quantize().
-     "T" means the transformation is obtained by png_set_tRNS_to_alpha().
-     "B" means the transformation is obtained by png_set_background(), or
-         png_strip_alpha().
+     "T" means the transformation is obtained by
+         png_set_tRNS_to_alpha().
+     "B" means the transformation is obtained by
+         png_set_background(), or png_strip_alpha().
 
 When an entry has multiple transforms listed all are required to cause the
 right overall transformation.  When two transforms are separated by a comma
@@ -1666,8 +1879,8 @@ with alpha.
 
     if (color_type == PNG_COLOR_TYPE_RGB ||
         color_type == PNG_COLOR_TYPE_RGB_ALPHA)
-       png_set_rgb_to_gray(png_ptr, error_action, double red_weight,
-          double green_weight);
+       png_set_rgb_to_gray(png_ptr, error_action,
+          double red_weight, double green_weight);
 
     error_action = 1: silently do the conversion
 
@@ -1689,7 +1902,8 @@ with alpha.
 In the corresponding fixed point API the red_weight and green_weight values are
 simply scaled by 100,000:
 
-    png_set_rgb_to_gray(png_ptr, error_action, png_fixed_point red_weight,
+    png_set_rgb_to_gray(png_ptr, error_action,
+       png_fixed_point red_weight,
        png_fixed_point green_weight);
 
 If you have set error_action = 1 or 2, you can
@@ -1733,7 +1947,7 @@ the current display (e.g., the background color from a web page).  You
 need to tell libpng how the color is represented, both the format of the
 component values in the color (the number of bits) and the gamma encoding of the
 color.  The function takes two arguments, background_gamma_mode and need_expand
-to convey this information, however only two combinations are likely to be
+to convey this information; however, only two combinations are likely to be
 useful:
 
     png_color_16 my_background;
@@ -1780,7 +1994,7 @@ value when you call it in this position:
       png_set_gamma(png_ptr, screen_gamma, 0.45455);
 
 If you need to reduce an RGB file to a paletted file, or if a paletted
-file has more entries then will fit on your screen, png_set_quantize()
+file has more entries than will fit on your screen, png_set_quantize()
 will do that.  Note that this is a simple match quantization that merely
 finds the closest color available.  This should work fairly well with
 optimized palettes, but fairly badly with linear color cubes.  If you
@@ -2027,7 +2241,7 @@ the second parameter NULL.
 
 If you don't want libpng to handle the interlacing details, just call
 png_read_rows() PNG_INTERLACE_ADAM7_PASSES times to read in all the images.
-Each of the images is a valid image by itself, however you will almost
+Each of the images is a valid image by itself; however, you will almost
 certainly need to distribute the pixels from each sub-image to the
 correct place.  This is where everything gets very tricky.
 
@@ -2118,10 +2332,15 @@ how pngvalid.c does it.
 Finishing a sequential read
 
 After you are finished reading the image through the
-low-level interface, you can finish reading the file.  If you are
-interested in comments or time, which may be stored either before or
-after the image data, you should pass the separate png_info struct if
-you want to keep the comments from before and after the image
+low-level interface, you can finish reading the file.
+
+If you want to use a different crc action for handling CRC errors in
+chunks after the image data, you can call png_set_crc_action()
+again at this point.
+
+If you are interested in comments or time, which may be stored either
+before or after the image data, you should pass the separate png_info
+struct if you want to keep the comments from before and after the image
 separate.
 
     png_infop end_info = png_create_info_struct(png_ptr);
@@ -2137,6 +2356,9 @@ separate.
 
 If you are not interested, you should still call png_read_end()
 but you can pass NULL, avoiding the need to create an end_info structure.
+If you do this, libpng will not process any chunks after IDAT other than
+skipping over them and perhaps (depending on whether you have called
+png_set_crc_action) checking their CRCs while looking for the IEND chunk.
 
    png_read_end(png_ptr, (png_infop)NULL);
 
@@ -2184,7 +2406,7 @@ sPLT, only the n'th item in the structure is freed, where n is "seq".
 The default behavior is only to free data that was allocated internally
 by libpng.  This can be changed, so that libpng will not free the data,
 or so that it will free data that was allocated by the user with png_malloc()
-or png_zalloc() and passed in via a png_set_*() function, with
+or png_calloc() and passed in via a png_set_*() function, with
 
     png_data_freer(png_ptr, info_ptr, freer, mask)
 
@@ -2205,7 +2427,7 @@ or png_destroy_*() is supposed to free the data.  When the user assumes
 responsibility for libpng-allocated data, the application must use
 png_free() to free it, and when the user transfers responsibility to libpng
 for data that the user has allocated, the user must have used png_malloc()
-or png_zalloc() to allocate it.
+or png_calloc() to allocate it.
 
 If you allocated your row_pointers in a single block, as suggested above in
 the description of the high level read interface, you must not transfer
@@ -2241,7 +2463,7 @@ For a more compact example of reading a PNG image, see the file example.c.
 
 Reading PNG files progressively
 
-The progressive reader is slightly different then the non-progressive
+The progressive reader is slightly different from the non-progressive
 reader.  Instead of calling png_read_info(), png_read_rows(), and
 png_read_end(), you make one call to png_process_data(), which calls
 callbacks when it has the info, a row, or the end of the image.  You
@@ -2325,7 +2547,7 @@ png_infop info_ptr;
        64K.  The library seems to run fine with sizes
        of 4K. Although you can give it much less if
        necessary (I assume you can give it chunks of
-       1 byte, I haven't tried less then 256 bytes
+       1 byte, I haven't tried less than 256 bytes
        yet).  When this function returns, you may
        want to display any rows that were generated
        in the row callback if you don't already do
@@ -2412,7 +2634,7 @@ png_infop info_ptr;
         png_progressive_combine_row(png_ptr, old_row,
           new_row);
 
-    /* where old_row is what was displayed for
+    /* where old_row is what was displayed
        previously for the row.  Note that the first
        pass (pass == 0, really) will completely cover
        the old row, so the rows do not have to be
@@ -2521,6 +2743,20 @@ You can #define PNG_ABORT() to a function that does something
 more useful than abort(), as long as your function does not
 return.
 
+Checking for invalid palette index on write was added at libpng
+1.5.10.  If a pixel contains an invalid (out-of-range) index libpng issues
+a benign error.  This is enabled by default because this condition is an
+error according to the PNG specification, Clause 11.3.2, but the error can
+be ignored in each png_ptr with
+
+   png_set_check_for_invalid_index(png_ptr, 0);
+
+If the error is ignored, or if png_benign_error() treats it as a warning,
+any invalid pixels are written as-is by the encoder, resulting in an
+invalid PNG datastream as output.  In this case the application is
+responsible for ensuring that the pixel indexes are in range when it writes
+a PLTE chunk with fewer entries than the bit depth would allow.
+
 Now you need to set up the output code.  The default for libpng is to
 use the C function fwrite().  If you use this, you will need to pass a
 valid FILE * in the function png_init_io().  Be sure that the file is
@@ -3023,18 +3259,53 @@ tEXt chunk use RFC 1123 format dates (e.g. "22 May 1997 18:07:10 GMT"),
 although this isn't a requirement.  Unlike the tIME chunk, the
 "Creation Time" tEXt chunk is not expected to be automatically changed
 by the software.  To facilitate the use of RFC 1123 dates, a function
-png_convert_to_rfc1123(png_timep) is provided to convert from PNG
-time to an RFC 1123 format string.
+png_convert_to_rfc1123_buffer(buffer, png_timep) is provided to
+convert from PNG time to an RFC 1123 format string.  The caller must provide
+a writeable buffer of at least 29 bytes.
 
 Writing unknown chunks
 
-You can use the png_set_unknown_chunks function to queue up chunks
-for writing.  You give it a chunk name, raw data, and a size; that's
-all there is to it.  The chunks will be written by the next following
-png_write_info_before_PLTE, png_write_info, or png_write_end function.
-Any chunks previously read into the info structure's unknown-chunk
-list will also be written out in a sequence that satisfies the PNG
-specification's ordering rules.
+You can use the png_set_unknown_chunks function to queue up private chunks
+for writing.  You give it a chunk name, location, raw data, and a size.  You
+also must use png_set_keep_unknown_chunks() to ensure that libpng will
+handle them.  That's all there is to it.  The chunks will be written by the
+next following png_write_info_before_PLTE, png_write_info, or png_write_end
+function, depending upon the specified location.  Any chunks previously
+read into the info structure's unknown-chunk list will also be written out
+in a sequence that satisfies the PNG specification's ordering rules.
+
+Here is an example of writing two private chunks, prVt and miNE:
+
+    #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
+    /* Set unknown chunk data */
+    png_unknown_chunk unk_chunk[2];
+    strcpy((char *) unk_chunk[0].name, "prVt";
+    unk_chunk[0].data = (unsigned char *) "PRIVATE DATA";
+    unk_chunk[0].size = strlen(unk_chunk[0].data)+1;
+    unk_chunk[0].location = PNG_HAVE_IHDR;
+    strcpy((char *) unk_chunk[1].name, "miNE";
+    unk_chunk[1].data = (unsigned char *) "MY CHUNK DATA";
+    unk_chunk[1].size = strlen(unk_chunk[0].data)+1;
+    unk_chunk[1].location = PNG_AFTER_IDAT;
+    png_set_unknown_chunks(write_ptr, write_info_ptr,
+        unk_chunk, 2);
+    /* Needed because miNE is not safe-to-copy */
+    png_set_keep_unknown_chunks(png, PNG_HANDLE_CHUNK_ALWAYS,
+       (png_bytep) "miNE", 1);
+    # if PNG_LIBPNG_VER < 10600
+      /* Deal with unknown chunk location bug in 1.5.x and earlier */
+      png_set_unknown_chunk_location(png, info, 0, PNG_HAVE_IHDR);
+      png_set_unknown_chunk_location(png, info, 1, PNG_AFTER_IDAT);
+    # endif
+    # if PNG_LIBPNG_VER < 10500
+      /* PNG_AFTER_IDAT writes two copies of the chunk prior to libpng-1.5.0,
+       * one before IDAT and another after IDAT, so don't use it; only use
+       * PNG_HAVE_IHDR location.  This call resets the location previously
+       * set by assignment and png_set_unknown_chunk_location() for chunk 1.
+       */
+      png_set_unknown_chunk_location(png, info, 1, PNG_HAVE_IHDR);
+    # endif
+    #endif
 
 The high-level write interface
 
@@ -3386,7 +3657,7 @@ png_destroy_write_struct().
 The default behavior is only to free data that was allocated internally
 by libpng.  This can be changed, so that libpng will not free the data,
 or so that it will free data that was allocated by the user with png_malloc()
-or png_zalloc() and passed in via a png_set_*() function, with
+or png_calloc() and passed in via a png_set_*() function, with
 
     png_data_freer(png_ptr, info_ptr, freer, mask)
 
@@ -3422,7 +3693,7 @@ When the user assumes responsibility for libpng-allocated data, the
 application must use
 png_free() to free it, and when the user transfers responsibility to libpng
 for data that the user has allocated, the user must have used png_malloc()
-or png_zalloc() to allocate it.
+or png_calloc() to allocate it.
 
 If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
 separately, do not transfer responsibility for freeing text_ptr to libpng,
@@ -3432,7 +3703,374 @@ if you transfer responsibility for free'ing text_ptr from libpng to your
 application, your application must not separately free those members.
 For a more compact example of writing a PNG image, see the file example.c.
 
-V. Modifying/Customizing libpng:
+V. Simplified API
+
+The simplified API, which became available in libpng-1.6.0, hides the details
+of both libpng and the PNG file format itself.
+It allows PNG files to be read into a very limited number of
+in-memory bitmap formats or to be written from the same formats.  If these
+formats do not accommodate your needs then you can, and should, use the more
+sophisticated APIs above - these support a wide variety of in-memory formats
+and a wide variety of sophisticated transformations to those formats as well
+as a wide variety of APIs to manipulate ancilliary information.
+
+To read a PNG file using the simplified API:
+
+  1) Declare a 'png_image' structure (see below) on the
+     stack and memset() it to all zero.
+
+  2) Call the appropriate png_image_begin_read... function.
+
+  3) Set the png_image 'format' member to the required
+     format and allocate a buffer for the image.
+
+  4) Call png_image_finish_read to read the image into
+     your buffer.
+
+There are no restrictions on the format of the PNG input itself; all valid
+color types, bit depths, and interlace methods are acceptable, and the
+input image is transformed as necessary to the requested in-memory format
+during the png_image_finish_read() step.
+
+To write a PNG file using the simplified API:
+
+  1) Declare a 'png_image' structure on the stack and memset()
+     it to all zero.
+
+  2) Initialize the members of the structure that describe the
+     image, setting the 'format' member to the format of the
+     image in memory.
+
+  3) Call the appropriate png_image_write... function with a
+     pointer to the image to write the PNG data.
+
+png_image is a structure that describes the in-memory format of an image
+when it is being read or define the in-memory format of an image that you
+need to write.  The "png_image" structure contains the following members:
+
+   png_uint_32  version Set to PNG_IMAGE_VERSION
+   png_uint_32  width   Image width in pixels (columns)
+   png_uint_32  height  Image height in pixels (rows)
+   png_uint_32  format  Image format as defined below
+   png_uint_32  flags   A bit mask containing informational flags
+   png_controlp opaque  Initialize to NULL, free with png_image_free
+   png_uint_32  colormap_entries; Number of entries in the color-map
+   png_uint_32  warning_or_error;
+   char         message[64];
+
+In the event of an error or warning the following field warning_or_error
+field will be set to a non-zero value and the 'message' field will contain
+a '\0' terminated string with the libpng error or warning message.  If both
+warnings and an error were encountered, only the error is recorded.  If there
+are multiple warnings, only the first one is recorded.
+
+The upper 30 bits of this value are reserved; the low two bits contain
+a two bit code such that a value more than 1 indicates a failure in the API
+just called:
+
+   0 - no warning or error
+   1 - warning
+   2 - error
+   3 - error preceded by warning
+
+The pixels (samples) of the image have one to four channels whose components
+have original values in the range 0 to 1.0:
+
+  1: A single gray or luminance channel (G).
+  2: A gray/luminance channel and an alpha channel (GA).
+  3: Three red, green, blue color channels (RGB).
+  4: Three color channels and an alpha channel (RGBA).
+
+The channels are encoded in one of two ways:
+
+  a) As a small integer, value 0..255, contained in a single byte.  For the
+alpha channel the original value is simply value/255.  For the color or
+luminance channels the value is encoded according to the sRGB specification
+and matches the 8-bit format expected by typical display devices.
+
+The color/gray channels are not scaled (pre-multiplied) by the alpha
+channel and are suitable for passing to color management software.
+
+  b) As a value in the range 0..65535, contained in a 2-byte integer, in
+the native byte order of the platform on which the application is running.
+All channels can be converted to the original value by dividing by 65535; all
+channels are linear.  Color channels use the RGB encoding (RGB end-points) of
+the sRGB specification.  This encoding is identified by the
+PNG_FORMAT_FLAG_LINEAR flag below.
+
+When an alpha channel is present it is expected to denote pixel coverage
+of the color or luminance channels and is returned as an associated alpha
+channel: the color/gray channels are scaled (pre-multiplied) by the alpha
+value.
+
+When a color-mapped image is used as a result of calling
+png_image_read_colormap or png_image_write_colormap the channels are encoded
+in the color-map and the descriptions above apply to the color-map entries.
+The image data is encoded as small integers, value 0..255, that index the
+entries in the color-map.  One integer (one byte) is stored for each pixel.
+
+PNG_FORMAT_*
+
+The #defines to be used in png_image::format.  Each #define identifies a
+particular layout of channel data and, if present, alpha values.  There are
+separate defines for each of the two channel encodings.
+
+A format is built up using single bit flag values.  Not all combinations are
+valid: use the bit flag values below for testing a format returned by the
+read APIs, but set formats from the derived values.
+
+When reading or writing color-mapped images the format should be set to the
+format of the entries in the color-map then png_image_{read,write}_colormap
+called to read or write the color-map and set the format correctly for the
+image data.  Do not set the PNG_FORMAT_FLAG_COLORMAP bit directly!
+
+NOTE: libpng can be built with particular features disabled, if you see
+compiler errors because the definition of one of the following flags has been
+compiled out it is because libpng does not have the required support.  It is
+possible, however, for the libpng configuration to enable the format on just
+read or just write; in that case you may see an error at run time.  You can
+guard against this by checking for the definition of:
+
+   PNG_SIMPLIFIED_{READ,WRITE}_{BGR,AFIRST}_SUPPORTED
+
+   PNG_FORMAT_FLAG_ALPHA    0x01 format with an alpha channel
+   PNG_FORMAT_FLAG_COLOR    0x02 color format: otherwise grayscale
+   PNG_FORMAT_FLAG_LINEAR   0x04 png_uint_16 channels else png_byte
+   PNG_FORMAT_FLAG_COLORMAP 0x08 libpng use only
+   PNG_FORMAT_FLAG_BGR      0x10 BGR colors, else order is RGB
+   PNG_FORMAT_FLAG_AFIRST   0x20 alpha channel comes first
+
+Supported formats are as follows.  Future versions of libpng may support more
+formats; for compatibility with older versions simply check if the format
+macro is defined using #ifdef.  These defines describe the in-memory layout
+of the components of the pixels of the image.
+
+First the single byte formats:
+
+   PNG_FORMAT_GRAY 0
+   PNG_FORMAT_GA   PNG_FORMAT_FLAG_ALPHA
+   PNG_FORMAT_AG   (PNG_FORMAT_GA|PNG_FORMAT_FLAG_AFIRST)
+   PNG_FORMAT_RGB  PNG_FORMAT_FLAG_COLOR
+   PNG_FORMAT_BGR  (PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_BGR)
+   PNG_FORMAT_RGBA (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_ALPHA)
+   PNG_FORMAT_ARGB (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_AFIRST)
+   PNG_FORMAT_BGRA (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_ALPHA)
+   PNG_FORMAT_ABGR (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_AFIRST)
+
+Then the linear 2-byte formats.  When naming these "Y" is used to
+indicate a luminance (gray) channel.  The component order within the pixel
+is always the same - there is no provision for swapping the order of the
+components in the linear format.  The components are 16-bit integers in
+the native byte order for your platform, and there is no provision for
+swapping the bytes to a different endian condition.
+
+   PNG_FORMAT_LINEAR_Y PNG_FORMAT_FLAG_LINEAR
+   PNG_FORMAT_LINEAR_Y_ALPHA
+      (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_ALPHA)
+   PNG_FORMAT_LINEAR_RGB
+      (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR)
+   PNG_FORMAT_LINEAR_RGB_ALPHA
+      (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR|
+      PNG_FORMAT_FLAG_ALPHA)
+
+Color-mapped formats are obtained by calling png_image_{read,write}_colormap,
+as appropriate after setting png_image::format to the format of the color-map
+to be read or written.  Applications may check the value of
+PNG_FORMAT_FLAG_COLORMAP to see if they have called the colormap API.  The
+format of the color-map may be extracted using the following macro.
+
+   PNG_FORMAT_OF_COLORMAP(fmt) ((fmt) & ~PNG_FORMAT_FLAG_COLORMAP)
+
+PNG_IMAGE macros
+
+These are convenience macros to derive information from a png_image
+structure.  The PNG_IMAGE_SAMPLE_ macros return values appropriate to the
+actual image sample values - either the entries in the color-map or the
+pixels in the image.  The PNG_IMAGE_PIXEL_ macros return corresponding values
+for the pixels and will always return 1 after a call to
+png_image_{read,write}_colormap.  The remaining macros return information
+about the rows in the image and the complete image.
+
+NOTE: All the macros that take a png_image::format parameter are compile time
+constants if the format parameter is, itself, a constant.  Therefore these
+macros can be used in array declarations and case labels where required.
+Similarly the macros are also pre-processor constants (sizeof is not used) so
+they can be used in #if tests.
+
+First the information about the samples.
+
+  PNG_IMAGE_SAMPLE_CHANNELS(fmt)
+    Returns the total number of channels in a given format: 1..4
+
+  PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt)
+    Returns the size in bytes of a single component of a pixel or color-map
+    entry (as appropriate) in the image.
+
+  PNG_IMAGE_SAMPLE_SIZE(fmt)
+    This is the size of the sample data for one sample.  If the image is
+    color-mapped it is the size of one color-map entry (and image pixels are
+    one byte in size), otherwise it is the size of one image pixel.
+
+  PNG_IMAGE_COLORMAP_SIZE(fmt)
+   The size of the color-map required by the format; this is the size of the
+   color-map buffer passed to the png_image_{read,write}_colormap APIs, it is
+   a fixed number determined by the format so can easily be allocated on the
+   stack if necessary.
+
+#define PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(fmt)\
+   (PNG_IMAGE_SAMPLE_CHANNELS(fmt) * 256)
+   /* The maximum size of the color-map required by the format expressed in a
+    * count of components.  This can be used to compile-time allocate a
+    * color-map:
+    *
+    * png_uint_16 colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(linear_fmt)];
+    *
+    * png_byte colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(sRGB_fmt)];
+    *
+    * Alternatively, use the PNG_IMAGE_COLORMAP_SIZE macro below to use the
+    * information from one of the png_image_begin_read_ APIs and dynamically
+    * allocate the required memory.
+    */
+
+
+Corresponding information about the pixels
+
+  PNG_IMAGE_PIXEL_(test,fmt)
+
+  PNG_IMAGE_PIXEL_CHANNELS(fmt)
+   The number of separate channels (components) in a pixel; 1 for a
+   color-mapped image.
+
+  PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)\
+   The size, in bytes, of each component in a pixel; 1 for a color-mapped
+   image.
+
+  PNG_IMAGE_PIXEL_SIZE(fmt)
+   The size, in bytes, of a complete pixel; 1 for a color-mapped image.
+
+Information about the whole row, or whole image
+
+  PNG_IMAGE_ROW_STRIDE(image)
+   Returns the total number of components in a single row of the image; this
+   is the minimum 'row stride', the minimum count of components between each
+   row.  For a color-mapped image this is the minimum number of bytes in a
+   row.
+
+   If you need the stride measured in bytes, row_stride_bytes is
+   PNG_IMAGE_ROW_STRIDE(image) * PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)
+   plus any padding bytes that your application might need, for example
+   to start the next row on a 4-byte boundary.
+
+  PNG_IMAGE_BUFFER_SIZE(image, row_stride)
+    Returns the size, in bytes, of an image buffer given a png_image and a row
+    stride - the number of components to leave space for in each row.  This
+    macro takes care of multiplying row_stride by PNG_IMAGE_PIXEL_COMONENT_SIZE
+    when the image has 2-byte components.
+
+  PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB == 0x01
+    This indicates the the RGB values of the in-memory bitmap do not
+    correspond to the red, green and blue end-points defined by sRGB.
+
+  PNG_IMAGE_FLAG_COLORMAP == 0x02
+    The PNG is color-mapped.  If this flag is set png_image_read_colormap
+    can be used without further loss of image information.  If it is not set
+    png_image_read_colormap will cause significant loss if the image has any
+
+READ APIs
+
+   The png_image passed to the read APIs must have been initialized by setting
+   the png_controlp field 'opaque' to NULL (or, better, memset the whole thing.)
+
+   int png_image_begin_read_from_file( png_imagep image,
+     const char *file_name)
+
+     The named file is opened for read and the image header
+     is filled in from the PNG header in the file.
+
+   int png_image_begin_read_from_stdio (png_imagep image,
+     FILE* file)
+
+      The PNG header is read from the stdio FILE object.
+
+   int png_image_begin_read_from_memory(png_imagep image,
+      png_const_voidp memory, png_size_t size)
+
+      The PNG header is read from the given memory buffer.
+
+   int png_image_finish_read(png_imagep image,
+      png_colorp background, void *buffer,
+      png_int_32 row_stride, void *colormap));
+
+      Finish reading the image into the supplied buffer and
+      clean up the png_image structure.
+
+      row_stride is the step, in png_byte or png_uint_16 units
+      as appropriate, between adjacent rows.  A positive stride
+      indicates that the top-most row is first in the buffer -
+      the normal top-down arrangement.  A negative stride
+      indicates that the bottom-most row is first in the buffer.
+
+      background need only be supplied if an alpha channel must
+      be removed from a png_byte format and the removal is to be
+      done by compositing on a solid color; otherwise it may be
+      NULL and any composition will be done directly onto the
+      buffer.  The value is an sRGB color to use for the
+      background, for grayscale output the green channel is used.
+
+      For linear output removing the alpha channel is always done
+      by compositing on black.
+
+   void png_image_free(png_imagep image)
+
+      Free any data allocated by libpng in image->opaque,
+      setting the pointer to NULL.  May be called at any time
+      after the structure is initialized.
+
+When the simplified API needs to convert between sRGB and linear colorspaces,
+the actual sRGB transfer curve defined in the sRGB specification (see the
+article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
+approximation used elsewhere in libpng.
+
+WRITE APIS
+
+For write you must initialize a png_image structure to describe the image to
+be written:
+
+   version: must be set to PNG_IMAGE_VERSION
+   opaque: must be initialized to NULL
+   width: image width in pixels
+   height: image height in rows
+   format: the format of the data you wish to write
+   flags: set to 0 unless one of the defined flags applies; set
+      PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB for color format images
+      where the RGB values do not correspond to the colors in sRGB.
+   colormap_entries: set to the number of entries in the color-map (0 to 256)
+
+   int png_image_write_to_file, (png_imagep image,
+      const char *file, int convert_to_8bit, const void *buffer,
+      png_int_32 row_stride, const void *colormap));
+
+      Write the image to the named file.
+
+   int png_image_write_to_stdio(png_imagep image, FILE *file,
+      int convert_to_8_bit, const void *buffer,
+      png_int_32 row_stride, const void *colormap)
+
+      Write the image to the given (FILE*).
+
+With all write APIs if image is in one of the linear formats with
+(png_uint_16) data then setting convert_to_8_bit will cause the output to be
+a (png_byte) PNG gamma encoded according to the sRGB specification, otherwise
+a 16-bit linear encoded PNG file is written.
+
+With all APIs row_stride is handled as in the read APIs - it is the spacing
+from one row to the next in component sized units (float) and if negative
+indicates a bottom-up row layout in the buffer.
+
+Note that the write API does not support interlacing, sub-8-bit pixels,
+and indexed (paletted) images.
+
+VI. Modifying/Customizing libpng
 
 There are two issues here.  The first is changing how libpng does
 standard things like memory allocation, input/output, and error handling.
@@ -3450,19 +4088,17 @@ in pngmem.c, pngrio.c, pngwio.c, and pngerror.c, respectively.  To change
 these functions, call the appropriate png_set_*_fn() function.
 
 Memory allocation is done through the functions png_malloc(), png_calloc(),
-and png_free().  These currently just call the standard C functions.
-png_calloc() calls png_malloc() and then clears the newly
-allocated memory to zero.  There is limited support for certain systems
-with segmented memory architectures and the types of pointers declared by
-png.h match this; you will have to use appropriate pointers in your
-application.  Since it is
-unlikely that the method of handling memory allocation on a platform
-will change between applications, these functions must be modified in
-the library at compile time.  If you prefer to use a different method
-of allocating and freeing data, you can use png_create_read_struct_2() or
-png_create_write_struct_2() to register your own functions as described
-above.  These functions also provide a void pointer that can be retrieved
-via
+and png_free().  The png_malloc() and png_free() functions currently just
+call the standard C functions and png_calloc() calls png_malloc() and then
+clears the newly allocated memory to zero; note that png_calloc(png_ptr, size)
+is not the same as the calloc(number, size) function provided by stdlib.h.
+There is limited support for certain systems with segmented memory
+architectures and the types of pointers declared by png.h match this; you
+will have to use appropriate pointers in your application.  If you prefer
+to use a different method of allocating and freeing data, you can use
+png_create_read_struct_2() or png_create_write_struct_2() to register your
+own functions as described above.  These functions also provide a void
+pointer that can be retrieved via
 
     mem_ptr=png_get_mem_ptr(png_ptr);
 
@@ -3565,6 +4201,18 @@ compiler documentation for more details.  For an alternative approach, you
 may wish to use the "cexcept" facility (see http://cexcept.sourceforge.net),
 which is illustrated in pngvalid.c and in contrib/visupng.
 
+Beginning in libpng-1.4.0, the png_set_benign_errors() API became available.
+You can use this to handle certain errors (normally handled as errors)
+as warnings.
+
+    png_set_benign_errors (png_ptr, int allowed);
+
+    allowed: 0: treat png_benign_error() as an error.
+             1: treat png_benign_error() as a warning.
+
+As of libpng-1.6.0, the default condition is to treat benign errors as
+warnings while reading and as errors while writing.
+
 Custom chunks
 
 If you need to read or write custom chunks, you may need to get deeper
@@ -3593,29 +4241,6 @@ the simpler ones to get an idea of how they work.  Try to find a similar
 transformation to the one you want to add and copy off of it.  More details
 can be found in the comments inside the code itself.
 
-Configuring for 16-bit platforms
-
-You will want to look into zconf.h to tell zlib (and thus libpng) that
-it cannot allocate more then 64K at a time.  Even if you can, the memory
-won't be accessible.  So limit zlib and libpng to 64K by defining MAXSEG_64K.
-
-Configuring for DOS
-
-For DOS users who only have access to the lower 640K, you will
-have to limit zlib's memory usage via a png_set_compression_mem_level()
-call.  See zlib.h or zconf.h in the zlib library for more information.
-
-Configuring for Medium Model
-
-Libpng's support for medium model has been tested on most of the popular
-compilers.  Make sure MAXSEG_64K gets defined, USE_FAR_KEYWORD gets
-defined, and FAR gets defined to far in pngconf.h, and you should be
-all set.  Everything in the library (except for zlib's structure) is
-expecting far data.  You must use the typedefs with the p or pp on
-the end for pointers (or at least look at them and be careful).  Make
-note that the rows of data are defined as png_bytepp, which is
-an "unsigned char far * far *".
-
 Configuring for gui/windowing platforms:
 
 You will need to write new error and warning functions that use the GUI
@@ -3625,18 +4250,6 @@ in order to have them available during the structure initialization.
 They can be changed later via png_set_error_fn().  On some compilers,
 you may also have to change the memory allocators (png_malloc, etc.).
 
-Configuring for compiler xxx:
-
-All includes for libpng are in pngconf.h.  If you need to add, change
-or delete an include, this is the place to do it.
-The includes that are not needed outside libpng are placed in pngpriv.h,
-which is only used by the routines inside libpng itself.
-The files in libpng proper only include pngpriv.h and png.h, which
-in turn includes pngconf.h and, as of libpng-1.5.0, pnglibconf.h.
-As of libpng-1.5.0, pngpriv.h also includes three other private header
-files, pngstruct.h, pnginfo.h, and pngdebug.h, which contain material
-that previously appeared in the public headers.
-
 Configuring zlib:
 
 There are special functions to configure the compression.  Perhaps the
@@ -3678,6 +4291,8 @@ zlib.h for more information on what these mean.
 
     png_set_compression_method(png_ptr, method);
 
+This controls the size of the IDAT chunks (default 8192):
+
     png_set_compression_buffer_size(png_ptr, size);
 
 As of libpng version 1.5.4, additional APIs became
@@ -3685,7 +4300,7 @@ available to set these separately for non-IDAT
 compressed chunks such as zTXt, iTXt, and iCCP:
 
     #include zlib.h
-    #if PNG_LIBPNG_VER <= 10504
+    #if PNG_LIBPNG_VER >= 10504
     png_set_text_compression_level(png_ptr, level);
 
     png_set_text_compression_mem_level(png_ptr, level);
@@ -3776,46 +4391,6 @@ Note that the numbers above were invented purely for this example and
 are given only to help explain the function usage.  Little testing has
 been done to find optimum values for either the costs or the weights.
 
-Removing unwanted object code
-
-There are a bunch of #define's in pngconf.h that control what parts of
-libpng are compiled.  All the defines end in _SUPPORTED.  If you are
-never going to use a capability, you can change the #define to #undef
-before recompiling libpng and save yourself code and data space, or
-you can turn off individual capabilities with defines that begin with
-PNG_NO_.
-
-In libpng-1.5.0 and later, the #define's are in pnglibconf.h instead.
-
-You can also turn all of the transforms and ancillary chunk capabilities
-off en masse with compiler directives that define
-PNG_NO_READ[or WRITE]_TRANSFORMS, or PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS,
-or all four,
-along with directives to turn on any of the capabilities that you do
-want.  The PNG_NO_READ[or WRITE]_TRANSFORMS directives disable the extra
-transformations but still leave the library fully capable of reading
-and writing PNG files with all known public chunks. Use of the
-PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS directive produces a library
-that is incapable of reading or writing ancillary chunks.  If you are
-not using the progressive reading capability, you can turn that off
-with PNG_NO_PROGRESSIVE_READ (don't confuse this with the INTERLACING
-capability, which you'll still have).
-
-All the reading and writing specific code are in separate files, so the
-linker should only grab the files it needs.  However, if you want to
-make sure, or if you are building a stand alone library, all the
-reading files start with "pngr" and all the writing files start with "pngw".
-The files that don't match either (like png.c, pngtrans.c, etc.)
-are used for both reading and writing, and always need to be included.
-The progressive reader is in pngpread.c
-
-If you are creating or distributing a dynamically linked library (a .so
-or DLL file), you should not remove or disable any parts of the library,
-as this will cause applications linked with different versions of the
-library to fail if they call functions not available in your library.
-The size of the library itself should not be an issue, because only
-those sections that are actually used will be loaded into memory.
-
 Requesting debug printout
 
 The macro definition PNG_DEBUG can be used to request debugging
@@ -3835,7 +4410,7 @@ the message, "message" is the formatted string to be printed,
 and p1 and p2 are parameters that are to be embedded in the string
 according to printf-style formatting directives.  For example,
 
-   png_debug1(2, "foo=%d\n", foo);
+   png_debug1(2, "foo=%d", foo);
 
 is expanded to
 
@@ -3853,7 +4428,7 @@ When PNG_DEBUG = 1, the macros are defined, but only png_debug statements
 having level = 0 will be printed.  There aren't any such statements in
 this version of libpng, but if you insert some they will be printed.
 
-VI.  MNG support
+VII.  MNG support
 
 The MNG specification (available at http://www.libpng.org/pub/mng) allows
 certain extensions to PNG for PNG images that are embedded in MNG datastreams.
@@ -3880,7 +4455,7 @@ or any other MNG chunks; your application must provide its own support for
 them.  You may wish to consider using libmng (available at
 http://www.libmng.com) instead.
 
-VII.  Changes to Libpng from version 0.88
+VIII.  Changes to Libpng from version 0.88
 
 It should be noted that versions of libpng later than 0.96 are not
 distributed by the original libpng author, Guy Schalnat, nor by
@@ -3915,6 +4490,9 @@ png_set_error_fn(), which is essentially the same function, but with a new
 name to force compilation errors with applications that try to use the old
 method.
 
+Support for the sCAL, iCCP, iTXt, and sPLT chunks was added at libpng-1.0.6;
+however, iTXt support was not enabled by default.
+
 Starting with version 1.0.7, you can find out which version of the library
 you are using at run-time:
 
@@ -3932,7 +4510,7 @@ application:
 
    png_uint_32 application_vn = PNG_LIBPNG_VER;
 
-VIII.  Changes to Libpng from version 1.0.x to 1.2.x
+IX.  Changes to Libpng from version 1.0.x to 1.2.x
 
 Support for user memory management was enabled by default.  To
 accomplish this, the functions png_create_read_struct_2(),
@@ -4029,7 +4607,7 @@ which also expands tRNS to alpha was replaced with
     png_set_expand_gray_1_2_4_to_8()
 which does not. It has been deprecated since libpng-1.0.18 and 1.2.9.
 
-IX.  Changes to Libpng from version 1.0.x/1.2.x to 1.4.x
+X.  Changes to Libpng from version 1.0.x/1.2.x to 1.4.x
 
 Private libpng prototypes and macro definitions were moved from
 png.h and pngconf.h into a new pngpriv.h header file.
@@ -4122,14 +4700,16 @@ png_set_strip_error_numbers() was removed from the library by default.
 
 The png_zalloc() and png_zfree() functions are no longer exported.
 The png_zalloc() function no longer zeroes out the memory that it
-allocates.
+allocates.  Applications that called png_zalloc(png_ptr, number, size)
+can call png_calloc(png_ptr, number*size) instead, and can call
+png_free() instead of png_zfree().
 
 Support for dithering was disabled by default in libpng-1.4.0, because
 it has not been well tested and doesn't actually "dither".
 The code was not
 removed, however, and could be enabled by building libpng with
 PNG_READ_DITHER_SUPPORTED defined.  In libpng-1.4.2, this support
-was reenabled, but the function was renamed png_set_quantize() to
+was re-enabled, but the function was renamed png_set_quantize() to
 reflect more accurately what it actually does.  At the same time,
 the PNG_DITHER_[RED,GREEN_BLUE]_BITS macros were also renamed to
 PNG_QUANTIZE_[RED,GREEN,BLUE]_BITS, and PNG_READ_DITHER_SUPPORTED
@@ -4137,37 +4717,61 @@ was renamed to PNG_READ_QUANTIZE_SUPPORTED.
 
 We removed the trailing '.' from the warning and error messages.
 
-X.  Changes to Libpng from version 1.4.x to 1.5.x
+XI.  Changes to Libpng from version 1.4.x to 1.5.x
 
 From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
 function) incorrectly returned a value of type png_uint_32.
+The incorrect macro was removed from libpng-1.4.5.
 
-Checking for invalid palette index on read or write was added at libpng
-1.5.10.  When an invalid index is found, libpng issues a benign error.
-This is enabled by default but can be disabled in each png_ptr with
+Checking for invalid palette index on write was added at libpng
+1.5.10.  If a pixel contains an invalid (out-of-range) index libpng issues
+a benign error.  This is enabled by default because this condition is an
+error according to the PNG specification, Clause 11.3.2, but the error can
+be ignored in each png_ptr with
 
    png_set_check_for_invalid_index(png_ptr, allowed);
 
       allowed  - one of
-                 0: disable
-                 1: enable
+                 0: disable benign error (accept the
+                    invalid data without warning).
+                 1: enable benign error (treat the
+                    invalid data as an error or a
+                    warning).
+
+If the error is ignored, or if png_benign_error() treats it as a warning,
+any invalid pixels are decoded as opaque black by the decoder and written
+as-is by the encoder.
+
+Retrieving the maximum palette index found was added at libpng-1.5.15.
+This statement must appear after png_read_png() or png_read_image() while
+reading, and after png_write_png() or png_write_image() while writing.
+
+   int max_palette = png_get_palette_max(png_ptr, info_ptr);
 
-A. Changes that affect users of libpng
+This will return the maximum palette index found in the image, or "-1" if
+the palette was not checked, or "0" if no palette was found.  Note that this
+does not account for any palette index used by ancillary chunks such as the
+bKGD chunk; you must check those separately to determine the maximum
+palette index actually used.
 
 There are no substantial API changes between the non-deprecated parts of
-the 1.4.5 API and the 1.5.0 API, however the ability to directly access
-the main libpng control structures, png_struct and png_info, deprecated
-in earlier versions of libpng, has been completely removed from
+the 1.4.5 API and the 1.5.0 API; however, the ability to directly access
+members of the main libpng control structures, png_struct and png_info,
+deprecated in earlier versions of libpng, has been completely removed from
 libpng 1.5.
 
-We no longer include zlib.h in png.h.  Applications that need access
-to information in zlib.h will need to add the '#include "zlib.h"'
-directive.  It does not matter whether it is placed prior to or after
+We no longer include zlib.h in png.h.  The include statement has been moved
+to pngstruct.h, where it is not accessible by applications. Applications that
+need access to information in zlib.h will need to add the '#include "zlib.h"'
+directive.  It does not matter whether this is placed prior to or after
 the '"#include png.h"' directive.
 
-We moved the png_strcpy(), png_strncpy(), png_strlen(), png_memcpy(),
-png_memcmp(), png_sprintf, and png_memcpy() macros into a private
-header file (pngpriv.h) that is not accessible to applications.
+The png_sprintf(), png_strcpy(), and png_strncpy() macros are no longer used
+and were removed.
+
+We moved the png_strlen(), png_memcpy(), png_memset(), and png_memcmp()
+macros into a private header file (pngpriv.h) that is not accessible to
+applications.
 
 In png_get_iCCP, the type of "profile" was changed from png_charpp
 to png_bytepp, and in png_set_iCCP, from png_charp to png_const_bytep.
@@ -4220,7 +4824,10 @@ and the accuracy of PNG fixed point values is insufficient for
 representation of these values. Consequently a "string" API
 (png_get_sCAL_s and png_set_sCAL_s) is the only reliable way of reading
 arbitrary sCAL chunks in the absence of either the floating point API or
-internal floating point calculations.
+internal floating point calculations.  Starting with libpng-1.5.0, both
+of these functions are present when PNG_sCAL_SUPPORTED is defined.  Prior
+to libpng-1.5.0, their presence also depended upon PNG_FIXED_POINT_SUPPORTED
+being defined and PNG_FLOATING_POINT_SUPPORTED not being defined.
 
 Applications no longer need to include the optional distribution header
 file pngusr.h or define the corresponding macros during application
@@ -4240,15 +4847,10 @@ reset by pngusr.h or by explicit settings on the compiler command line.
 These settings may produce compiler warnings or errors in 1.5.0 because
 of macro redefinition.
 
-From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
-function) incorrectly returned a value of type png_uint_32.  libpng 1.5.0
-is consistent with the implementation in 1.4.5 and 1.2.x (where the macro
-did not exist.)
-
 Applications can now choose whether to use these macros or to call the
 corresponding function by defining PNG_USE_READ_MACROS or
 PNG_NO_USE_READ_MACROS before including png.h.  Notice that this is
-only supported from 1.5.0 -defining PNG_NO_USE_READ_MACROS prior to 1.5.0
+only supported from 1.5.0; defining PNG_NO_USE_READ_MACROS prior to 1.5.0
 will lead to a link failure.
 
 Prior to libpng-1.5.4, the zlib compressor used the same set of parameters
@@ -4262,7 +4864,10 @@ option was off by default, and slightly inaccurate scaling occurred.
 This option can no longer be turned off, and the choice of accurate
 or inaccurate 16-to-8 scaling is by using the new png_set_scale_16_to_8()
 API for accurate scaling or the old png_set_strip_16_to_8() API for simple
-chopping.
+chopping.  In libpng-1.5.4, the PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
+macro became PNG_READ_SCALE_16_TO_8_SUPPORTED, and the PNG_READ_16_TO_8
+macro became PNG_READ_STRIP_16_TO_8_SUPPORTED, to enable the two
+png_set_*_16_to_8() functions separately.
 
 Prior to libpng-1.5.4, the png_set_user_limits() function could only be
 used to reduce the width and height limits from the value of
@@ -4284,25 +4889,8 @@ limits are now
    png_user_chunk_cache_max  0 (unlimited)   128
    png_user_chunk_malloc_max 0 (unlimited) 8,000,000
 
-B. Changes to the build and configuration of libpng
-
-Details of internal changes to the library code can be found in the CHANGES
-file and in the GIT repository logs.  These will be of no concern to the vast
-majority of library users or builders, however the few who configure libpng
-to a non-default feature set may need to change how this is done.
-
-There should be no need for library builders to alter build scripts if
-these use the distributed build support - configure or the makefiles -
-however users of the makefiles may care to update their build scripts
-to build pnglibconf.h where the corresponding makefile does not do so.
-
-Building libpng with a non-default configuration has changed completely.
-The old method using pngusr.h should still work correctly even though the
-way pngusr.h is used in the build has been changed; however, library
-builders will probably want to examine the changes to take advantage of
-new capabilities and to simplify their build system.
-
-B.1 Specific changes to library configuration capabilities
+The png_set_option() function (and the "options" member of the png struct) was
+added to libpng-1.5.15.
 
 The library now supports a complete fixed point implementation and can
 thus be used on systems that have no floating point support or very
@@ -4314,27 +4902,7 @@ independent of the choice of fixed versus floating point APIs and all the
 missing fixed point APIs have been implemented.
 
 The exact mechanism used to control attributes of API functions has
-changed.  A single set of operating system independent macro definitions
-is used and operating system specific directives are defined in
-pnglibconf.h
-
-As part of this the mechanism used to choose procedure call standards on
-those systems that allow a choice has been changed.  At present this only
-affects certain Microsoft (DOS, Windows) and IBM (OS/2) operating systems
-running on Intel processors.  As before, PNGAPI is defined where required
-to control the exported API functions; however, two new macros, PNGCBAPI
-and PNGCAPI, are used instead for callback functions (PNGCBAPI) and
-(PNGCAPI) for functions that must match a C library prototype (currently
-only png_longjmp_ptr, which must match the C longjmp function.)  The new
-approach is documented in pngconf.h
-
-Despite these changes, libpng 1.5.0 only supports the native C function
-calling standard on those platforms tested so far (__cdecl on Microsoft
-Windows).  This is because the support requirements for alternative
-calling conventions seem to no longer exist.  Developers who find it
-necessary to set PNG_API_RULE to 1 should advise the mailing list
-(png-mng-implement) of this and library builders who use Openwatcom and
-therefore set PNG_API_RULE to 2 should also contact the mailing list.
+changed, as described in the INSTALL file.
 
 A new test program, pngvalid, is provided in addition to pngtest.
 pngvalid validates the arithmetic accuracy of the gamma correction
@@ -4399,7 +4967,7 @@ merely stops the function from being exported.
 PNG_FLOATING_ARITHMETIC_SUPPORTED chooses between the internal floating
 point implementation or the fixed point one.  Typically the fixed point
 implementation is larger and slower than the floating point implementation
-on a system that supports floating point, however it may be faster on a
+on a system that supports floating point; however, it may be faster on a
 system which lacks floating point hardware and therefore uses a software
 emulation.
 
@@ -4410,47 +4978,138 @@ even though the default is to use the macros - this allows applications
 to choose at app buildtime whether or not to use macros (previously
 impossible because the functions weren't in the default build.)
 
-B.2 Changes to the configuration mechanism
-
-Prior to libpng-1.5.0 library builders who needed to configure libpng
-had either to modify the exported pngconf.h header file to add system
-specific configuration or had to write feature selection macros into
-pngusr.h and cause this to be included into pngconf.h by defining
-PNG_USER_CONFIG. The latter mechanism had the disadvantage that an
-application built without PNG_USER_CONFIG defined would see the
-unmodified, default, libpng API and thus would probably fail to link.
-
-These mechanisms still work in the configure build and in any makefile
-build that builds pnglibconf.h, although the feature selection macros
-have changed somewhat as described above.  In 1.5.0, however, pngusr.h is
-processed only once, when the exported header file pnglibconf.h is built.
-pngconf.h no longer includes pngusr.h, therefore pngusr.h is ignored after the
-build of pnglibconf.h and it is never included in an application build.
-
-The rarely used alternative of adding a list of feature macros to the
-CFLAGS setting in the build also still works, however the macros will be
-copied to pnglibconf.h and this may produce macro redefinition warnings
-when the individual C files are compiled.
-
-All configuration now only works if pnglibconf.h is built from
-scripts/pnglibconf.dfa.  This requires the program awk.  Brian Kernighan
-(the original author of awk) maintains C source code of that awk and this
-and all known later implementations (often called by subtly different
-names - nawk and gawk for example) are adequate to build pnglibconf.h.
-The Sun Microsystems (now Oracle) program 'awk' is an earlier version
-and does not work; this may also apply to other systems that have a
-functioning awk called 'nawk'.
-
-Configuration options are now documented in scripts/pnglibconf.dfa.  This
-file also includes dependency information that ensures a configuration is
-consistent; that is, if a feature is switched off dependent features are
-also removed.  As a recommended alternative to using feature macros in
-pngusr.h a system builder may also define equivalent options in pngusr.dfa
-(or, indeed, any file) and add that to the configuration by setting
-DFA_XTRA to the file name.  The makefiles in contrib/pngminim illustrate
-how to do this, and a case where pngusr.h is still required.
-
-XI. Detecting libpng
+XII.  Changes to Libpng from version 1.5.x to 1.6.x
+
+A "simplified API" has been added (see documentation in png.h and a simple
+example in contrib/examples/pngtopng.c).  The new publicly visible API
+includes the following:
+
+   macros:
+     PNG_FORMAT_*
+     PNG_IMAGE_*
+   structures:
+     png_control
+     png_image
+   read functions
+     png_image_begin_read_from_file()
+     png_image_begin_read_from_stdio()
+     png_image_begin_read_from_memory()
+     png_image_finish_read()
+     png_image_free()
+   write functions
+     png_image_write_to_file()
+     png_image_write_to_stdio()
+
+Starting with libpng-1.6.0, you can configure libpng to prefix all exported
+symbols, using the PNG_PREFIX macro.
+
+We no longer include string.h in png.h.  The include statement has been moved
+to pngpriv.h, where it is not accessible by applications.  Applications that
+need access to information in string.h must add an '#include <string.h>'
+directive.  It does not matter whether this is placed prior to or after
+the '#include "png.h"' directive.
+
+The following API are now DEPRECATED:
+   png_info_init_3()
+   png_convert_to_rfc1123() which has been replaced
+     with png_convert_to_rfc1123_buffer()
+   png_malloc_default()
+   png_free_default()
+   png_reset_zstream()
+
+The following have been removed:
+   png_get_io_chunk_name(), which has been replaced
+     with png_get_io_chunk_type().  The new
+     function returns a 32-bit integer instead of
+     a string.
+   The png_sizeof(), png_strlen(), png_memcpy(), png_memcmp(), and
+     png_memset() macros are no longer used in the libpng sources and
+     have been removed.  These had already been made invisible to applications
+     (i.e., defined in the private pngpriv.h header file) since libpng-1.5.0.
+
+The signatures of many exported functions were changed, such that
+   png_structp became png_structrp or png_const_structrp
+   png_infop became png_inforp or png_const_inforp
+where "rp" indicates a "restricted pointer".
+
+The support for FAR/far types has been eliminated and the definition of
+png_alloc_size_t is now controlled by a flag so that 'small size_t' systems
+can select it if necessary.
+
+Error detection in some chunks has improved; in particular the iCCP chunk
+reader now does pretty complete validation of the basic format.  Some bad
+profiles that were previously accepted are now accepted with a warning or
+rejected, depending upon the png_set_benign_errors() setting, in particular
+the very old broken Microsoft/HP 3144-byte sRGB profile.  Starting with
+libpng-1.6.11, recognizing and checking sRGB profiles can be avoided by
+means of
+
+    #if defined(PNG_SKIP_sRGB_CHECK_PROFILE) && \
+        defined(PNG_SET_OPTION_SUPPORTED)
+       png_set_option(png_ptr, PNG_SKIP_sRGB_CHECK_PROFILE,
+           PNG_OPTION_ON);
+    #endif
+
+It's not a good idea to do this if you are using the "simplified API",
+which needs to be able to recognize sRGB profiles conveyed via the iCCP
+chunk.
+
+The PNG spec requirement that only grayscale profiles may appear in images
+with color type 0 or 4 and that even if the image only contains gray pixels,
+only RGB profiles may appear in images with color type 2, 3, or 6, is now
+enforced.  The sRGB chunk is allowed to appear in images with any color type
+and is interpreted by libpng to convey a one-tracer-curve gray profile or a
+three-tracer-curve RGB profile as appropriate.
+
+Prior to libpng-1.6.0 a warning would be issued if the iTXt chunk contained
+an empty language field or an empty translated keyword.  Both of these
+are allowed by the PNG specification, so these warnings are no longer issued.
+
+The library now issues an error if the application attempts to set a
+transform after it calls png_read_update_info() or if it attempts to call
+both png_read_update_info() and png_start_read_image() or to call either
+of them more than once.
+
+The default condition for benign_errors is now to treat benign errors as
+warnings while reading and as errors while writing.
+
+The library now issues a warning if both background processing and RGB to
+gray are used when gamma correction happens. As with previous versions of
+the library the results are numerically very incorrect in this case.
+
+There are some minor arithmetic changes in some transforms such as
+png_set_background(), that might be detected by certain regression tests.
+
+Unknown chunk handling has been improved internally, without any API change.
+This adds more correct option control of the unknown handling, corrects
+a pre-existing bug where the per-chunk 'keep' setting is ignored, and makes
+it possible to skip IDAT chunks in the sequential reader.
+
+The machine-generated configure files are no longer included in branches
+libpng16 and later of the GIT repository.  They continue to be included
+in the tarball releases, however.
+
+Libpng-1.6.0 through 1.6.2 used the CMF bytes at the beginning of the IDAT
+stream to set the size of the sliding window for reading instead of using the
+default 32-kbyte sliding window size.  It was discovered that there are
+hundreds of PNG files in the wild that have incorrect CMF bytes that caused
+zlib to issue the "invalid distance too far back" error and reject the file.
+Libpng-1.6.3 and later calculate their own safe CMF from the image dimensions,
+provide a way to revert to the libpng-1.5.x behavior (ignoring the CMF bytes
+and using a 32-kbyte sliding window), by using
+
+    png_set_option(png_ptr, PNG_MAXIMUM_INFLATE_WINDOW,
+        PNG_OPTION_ON);
+
+and provide a tool (contrib/tools/pngfix) for rewriting a PNG file while
+optimizing the CMF bytes in its IDAT chunk correctly.
+
+Libpng-1.6.0 and libpng-1.6.1 wrote uncompressed iTXt chunks with the wrong
+length, which resulted in PNG files that cannot be read beyond the bad iTXt
+chunk.  This error was fixed in libpng-1.6.3, and a tool (called
+contrib/tools/png-fix-itxt) has been added to the libpng distribution.
+
+XIII.  Detecting libpng
 
 The png_get_io_ptr() function has been present since libpng-0.88, has never
 changed, and is unaffected by conditional compilation macros.  It is the
@@ -4459,18 +5118,18 @@ libpng version since 0.88.  In an autoconf "configure.in" you could use
 
     AC_CHECK_LIB(png, png_get_io_ptr, ...
 
-XII. Source code repository
+XV. Source code repository
 
 Since about February 2009, version 1.2.34, libpng has been under "git" source
 control.  The git repository was built from old libpng-x.y.z.tar.gz files
 going back to version 0.70.  You can access the git repository (read only)
 at
 
-    git://libpng.git.sourceforge.net/gitroot/libpng
+    git://git.code.sf.net/p/libpng/code
 
-or you can browse it via "gitweb" at
+or you can browse it with a web browser by selecting the "code" button at
 
-    http://libpng.git.sourceforge.net/git/gitweb.cgi?p=libpng
+    https://sourceforge.net/projects/libpng
 
 Patches can be sent to glennrp at users.sourceforge.net or to
 png-mng-implement at lists.sourceforge.net or you can upload them to
@@ -4483,9 +5142,10 @@ simple verbal discriptions of bug fixes, reported either to the
 SourceForge bug tracker, to the png-mng-implement at lists.sf.net
 mailing list, or directly to glennrp.
 
-XIII. Coding style
+XV. Coding style
 
-Our coding style is similar to the "Allman" style, with curly
+Our coding style is similar to the "Allman" style
+(See http://en.wikipedia.org/wiki/Indent_style#Allman_style), with curly
 braces on separate lines:
 
     if (condition)
@@ -4548,6 +5208,9 @@ exported functions are marked with PNGAPI:
     body;
  }
 
+The return type and decorations are placed on a separate line
+ahead of the function name, as illustrated above.
+
 The prototypes for all exported functions appear in png.h,
 above the comment that says
 
@@ -4562,17 +5225,29 @@ We mark all non-exported functions with "/* PRIVATE */"":
  }
 
 The prototypes for non-exported functions (except for those in
-pngtest) appear in
-pngpriv.h
-above the comment that says
+pngtest) appear in pngpriv.h above the comment that says
 
-  /* Maintainer: Put new private prototypes here ^ and in libpngpf.3 */
+  /* Maintainer: Put new private prototypes here ^ */
 
 To avoid polluting the global namespace, the names of all exported
 functions and variables begin with "png_", and all publicly visible C
 preprocessor macros begin with "PNG".  We request that applications that
 use libpng *not* begin any of their own symbols with either of these strings.
 
+We put a space after the "sizeof" operator and we omit the
+optional parentheses around its argument when the argument
+is an expression, not a type name, and we always enclose the
+sizeof operator, with its argument, in parentheses:
+
+  (sizeof (png_uint_32))
+  (sizeof array)
+
+Prior to libpng-1.6.0 we used a "png_sizeof()" macro, formatted as
+though it were a function.
+
+Control keywords if, for, while, and switch are always followed by a space
+to distinguish them from function calls, which have no trailing space. 
+
 We put a space after each comma and after each semicolon
 in "for" statements, and we put spaces before and after each
 C binary operator and after "for" or "while", and before
@@ -4583,44 +5258,52 @@ left parenthesis that follows it:
     for (i = 2; i > 0; --i)
        y[i] = a(x) + (int)b;
 
-We prefer #ifdef and #ifndef to #if defined() and if !defined()
-when there is only one macro being tested.
+We prefer #ifdef and #ifndef to #if defined() and #if !defined()
+when there is only one macro being tested.  We always use parentheses
+with "defined".
 
 We prefer to express integers that are used as bit masks in hex format,
 with an even number of lower-case hex digits (e.g., 0x00, 0xff, 0x0100).
 
+We prefer to use underscores in variable names rather than camelCase, except
+for a few type names that we inherit from zlib.h.
+
+We prefer "if (something != 0)" and "if (something == 0)"
+over "if (something)" and if "(!something)", respectively.
+
 We do not use the TAB character for indentation in the C sources.
 
 Lines do not exceed 80 characters.
 
 Other rules can be inferred by inspecting the libpng source.
 
-XIV. Y2K Compliance in libpng
+XVI. Y2K Compliance in libpng
 
-March 29, 2012
+March 26, 2015
 
 Since the PNG Development group is an ad-hoc body, we can't make
 an official declaration.
 
 This is your unofficial assurance that libpng from version 0.71 and
-upward through 1.5.10 are Y2K compliant.  It is my belief that earlier
+upward through 1.6.17 are Y2K compliant.  It is my belief that earlier
 versions were also Y2K compliant.
 
-Libpng only has three year fields.  One is a 2-byte unsigned integer that
-will hold years up to 65535.  The other two hold the date in text
-format, and will hold years up to 9999.
+Libpng only has two year fields.  One is a 2-byte unsigned integer
+that will hold years up to 65535.  The other, which is deprecated,
+holds the date in text format, and will hold years up to 9999.
 
 The integer is
     "png_uint_16 year" in png_time_struct.
 
-The strings are
-    "png_charp time_buffer" in png_struct and
-    "near_time_buffer", which is a local character string in png.c.
+The string is
+    "char time_buffer[29]" in png_struct.  This is no longer used
+in libpng-1.6.x and will be removed from libpng-1.7.0.
 
 There are seven time-related functions:
 
-    png_convert_to_rfc_1123() in png.c
-      (formerly png_convert_to_rfc_1152() in error)
+    png_convert_to_rfc_1123_buffer() in png.c
+      (formerly png_convert_to_rfc_1152() in error, and
+      also formerly png_convert_to_rfc_1123())
     png_convert_from_struct_tm() in pngwrite.c, called
       in pngwrite.c
     png_convert_from_time_t() in pngwrite.c
diff --git a/src/3rdparty/libpng/png.c b/src/3rdparty/libpng/png.c
index cba18ba..7575ede 100644
--- a/src/3rdparty/libpng/png.c
+++ b/src/3rdparty/libpng/png.c
@@ -1,8 +1,8 @@
 
 /* png.c - location for general purpose libpng functions
  *
- * Last changed in libpng 1.5.10 [March 8, 2012]
- * Copyright (c) 1998-2012 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.17 [March 26, 2015]
+ * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
@@ -14,7 +14,7 @@
 #include "pngpriv.h"
 
 /* Generate a compiler error if there is an old png.h in the search path. */
-typedef png_libpng_version_1_5_10 Your_png_h_is_not_version_1_5_10;
+typedef png_libpng_version_1_6_17 Your_png_h_is_not_version_1_6_17;
 
 /* Tells libpng that we have already handled the first "num_bytes" bytes
  * of the PNG file signature.  If the PNG data is embedded into another
@@ -24,7 +24,7 @@ typedef png_libpng_version_1_5_10 Your_png_h_is_not_version_1_5_10;
 
 #ifdef PNG_READ_SUPPORTED
 void PNGAPI
-png_set_sig_bytes(png_structp png_ptr, int num_bytes)
+png_set_sig_bytes(png_structrp png_ptr, int num_bytes)
 {
    png_debug(1, "in png_set_sig_bytes");
 
@@ -34,7 +34,7 @@ png_set_sig_bytes(png_structp png_ptr, int num_bytes)
    if (num_bytes > 8)
       png_error(png_ptr, "Too many bytes for PNG signature");
 
-   png_ptr->sig_bytes = (png_byte)(num_bytes < 0 ? 0 : num_bytes);
+   png_ptr->sig_bytes = (png_byte)((num_bytes < 0 ? 0 : num_bytes) & 0xff);
 }
 
 /* Checks whether the supplied bytes match the PNG signature.  We allow
@@ -62,50 +62,44 @@ png_sig_cmp(png_const_bytep sig, png_size_t start, png_size_t num_to_check)
    if (start + num_to_check > 8)
       num_to_check = 8 - start;
 
-   return ((int)(png_memcmp(&sig[start], &png_signature[start], num_to_check)));
+   return ((int)(memcmp(&sig[start], &png_signature[start], num_to_check)));
 }
 
-#endif /* PNG_READ_SUPPORTED */
+#endif /* READ */
 
 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
 /* Function to allocate memory for zlib */
 PNG_FUNCTION(voidpf /* PRIVATE */,
 png_zalloc,(voidpf png_ptr, uInt items, uInt size),PNG_ALLOCATED)
 {
-   png_voidp ptr;
-   png_structp p=(png_structp)png_ptr;
-   png_uint_32 save_flags=p->flags;
-   png_alloc_size_t num_bytes;
+   png_alloc_size_t num_bytes = size;
 
    if (png_ptr == NULL)
-      return (NULL);
+      return NULL;
 
-   if (items > PNG_UINT_32_MAX/size)
+   if (items >= (~(png_alloc_size_t)0)/size)
    {
-     png_warning (p, "Potential overflow in png_zalloc()");
-     return (NULL);
+      png_warning (png_voidcast(png_structrp, png_ptr),
+         "Potential overflow in png_zalloc()");
+      return NULL;
    }
-   num_bytes = (png_alloc_size_t)items * size;
-
-   p->flags|=PNG_FLAG_MALLOC_NULL_MEM_OK;
-   ptr = (png_voidp)png_malloc((png_structp)png_ptr, num_bytes);
-   p->flags=save_flags;
 
-   return ((voidpf)ptr);
+   num_bytes *= items;
+   return png_malloc_warn(png_voidcast(png_structrp, png_ptr), num_bytes);
 }
 
 /* Function to free memory for zlib */
 void /* PRIVATE */
 png_zfree(voidpf png_ptr, voidpf ptr)
 {
-   png_free((png_structp)png_ptr, (png_voidp)ptr);
+   png_free(png_voidcast(png_const_structrp,png_ptr), ptr);
 }
 
 /* Reset the CRC variable to 32 bits of 1's.  Care must be taken
  * in case CRC is > 32 bits to leave the top bits 0.
  */
 void /* PRIVATE */
-png_reset_crc(png_structp png_ptr)
+png_reset_crc(png_structrp png_ptr)
 {
    /* The cast is safe because the crc is a 32 bit value. */
    png_ptr->crc = (png_uint_32)crc32(0, Z_NULL, 0);
@@ -117,11 +111,11 @@ png_reset_crc(png_structp png_ptr)
  * trouble of calculating it.
  */
 void /* PRIVATE */
-png_calculate_crc(png_structp png_ptr, png_const_bytep ptr, png_size_t length)
+png_calculate_crc(png_structrp png_ptr, png_const_bytep ptr, png_size_t length)
 {
    int need_crc = 1;
 
-   if (PNG_CHUNK_ANCILLIARY(png_ptr->chunk_name))
+   if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0)
    {
       if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
           (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
@@ -130,33 +124,35 @@ png_calculate_crc(png_structp png_ptr, png_const_bytep ptr, png_size_t length)
 
    else /* critical */
    {
-      if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
+      if ((png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) != 0)
          need_crc = 0;
    }
 
-   /* 'uLong' is defined as unsigned long, this means that on some systems it is
-    * a 64 bit value.  crc32, however, returns 32 bits so the following cast is
-    * safe.  'uInt' may be no more than 16 bits, so it is necessary to perform a
-    * loop here.
+   /* 'uLong' is defined in zlib.h as unsigned long; this means that on some
+    * systems it is a 64 bit value.  crc32, however, returns 32 bits so the
+    * following cast is safe.  'uInt' may be no more than 16 bits, so it is
+    * necessary to perform a loop here.
     */
-   if (need_crc && length > 0)
+   if (need_crc != 0 && length > 0)
    {
       uLong crc = png_ptr->crc; /* Should never issue a warning */
 
       do
       {
-         uInt safeLength = (uInt)length;
-         if (safeLength == 0)
-            safeLength = (uInt)-1; /* evil, but safe */
+         uInt safe_length = (uInt)length;
+#ifndef __COVERITY__
+         if (safe_length == 0)
+            safe_length = (uInt)-1; /* evil, but safe */
+#endif
 
-         crc = crc32(crc, ptr, safeLength);
+         crc = crc32(crc, ptr, safe_length);
 
-         /* The following should never issue compiler warnings, if they do the
+         /* The following should never issue compiler warnings; if they do the
           * target system has characteristics that will probably violate other
           * assumptions within the libpng code.
           */
-         ptr += safeLength;
-         length -= safeLength;
+         ptr += safe_length;
+         length -= safe_length;
       }
       while (length > 0);
 
@@ -166,97 +162,205 @@ png_calculate_crc(png_structp png_ptr, png_const_bytep ptr, png_size_t length)
 }
 
 /* Check a user supplied version number, called from both read and write
- * functions that create a png_struct
+ * functions that create a png_struct.
  */
 int
-png_user_version_check(png_structp png_ptr, png_const_charp user_png_ver)
+png_user_version_check(png_structrp png_ptr, png_const_charp user_png_ver)
 {
-   if (user_png_ver)
+     /* Libpng versions 1.0.0 and later are binary compatible if the version
+      * string matches through the second '.'; we must recompile any
+      * applications that use any older library version.
+      */
+
+   if (user_png_ver != NULL)
    {
-      int i = 0;
+      int i = -1;
+      int found_dots = 0;
 
       do
       {
-         if (user_png_ver[i] != png_libpng_ver[i])
+         i++;
+         if (user_png_ver[i] != PNG_LIBPNG_VER_STRING[i])
             png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
-      } while (png_libpng_ver[i++]);
+         if (user_png_ver[i] == '.')
+            found_dots++;
+      } while (found_dots < 2 && user_png_ver[i] != 0 &&
+            PNG_LIBPNG_VER_STRING[i] != 0);
    }
 
    else
       png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
 
-   if (png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH)
+   if ((png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH) != 0)
    {
-     /* Libpng 0.90 and later are binary incompatible with libpng 0.89, so
-      * we must recompile any applications that use any older library version.
-      * For versions after libpng 1.0, we will be compatible, so we need
-      * only check the first digit.
-      */
-      if (user_png_ver == NULL || user_png_ver[0] != png_libpng_ver[0] ||
-          (user_png_ver[0] == '1' && user_png_ver[2] != png_libpng_ver[2]) ||
-          (user_png_ver[0] == '0' && user_png_ver[2] < '9'))
-      {
 #ifdef PNG_WARNINGS_SUPPORTED
-         size_t pos = 0;
-         char m[128];
+      size_t pos = 0;
+      char m[128];
 
-         pos = png_safecat(m, sizeof m, pos, "Application built with libpng-");
-         pos = png_safecat(m, sizeof m, pos, user_png_ver);
-         pos = png_safecat(m, sizeof m, pos, " but running with ");
-         pos = png_safecat(m, sizeof m, pos, png_libpng_ver);
+      pos = png_safecat(m, (sizeof m), pos,
+          "Application built with libpng-");
+      pos = png_safecat(m, (sizeof m), pos, user_png_ver);
+      pos = png_safecat(m, (sizeof m), pos, " but running with ");
+      pos = png_safecat(m, (sizeof m), pos, PNG_LIBPNG_VER_STRING);
+      PNG_UNUSED(pos)
 
-         png_warning(png_ptr, m);
+      png_warning(png_ptr, m);
 #endif
 
 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
-         png_ptr->flags = 0;
+      png_ptr->flags = 0;
 #endif
 
-         return 0;
-      }
+      return 0;
    }
 
    /* Success return. */
    return 1;
 }
 
-/* Allocate the memory for an info_struct for the application.  We don't
- * really need the png_ptr, but it could potentially be useful in the
- * future.  This should be used in favour of malloc(png_sizeof(png_info))
- * and png_info_init() so that applications that want to use a shared
- * libpng don't have to be recompiled if png_info changes size.
+/* Generic function to create a png_struct for either read or write - this
+ * contains the common initialization.
  */
+PNG_FUNCTION(png_structp /* PRIVATE */,
+png_create_png_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
+    png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
+    png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
+{
+   png_struct create_struct;
+#  ifdef PNG_SETJMP_SUPPORTED
+      jmp_buf create_jmp_buf;
+#  endif
+
+   /* This temporary stack-allocated structure is used to provide a place to
+    * build enough context to allow the user provided memory allocator (if any)
+    * to be called.
+    */
+   memset(&create_struct, 0, (sizeof create_struct));
+
+   /* Added at libpng-1.2.6 */
+#  ifdef PNG_USER_LIMITS_SUPPORTED
+      create_struct.user_width_max = PNG_USER_WIDTH_MAX;
+      create_struct.user_height_max = PNG_USER_HEIGHT_MAX;
+
+#     ifdef PNG_USER_CHUNK_CACHE_MAX
+         /* Added at libpng-1.2.43 and 1.4.0 */
+         create_struct.user_chunk_cache_max = PNG_USER_CHUNK_CACHE_MAX;
+#     endif
+
+#     ifdef PNG_USER_CHUNK_MALLOC_MAX
+         /* Added at libpng-1.2.43 and 1.4.1, required only for read but exists
+          * in png_struct regardless.
+          */
+         create_struct.user_chunk_malloc_max = PNG_USER_CHUNK_MALLOC_MAX;
+#     endif
+#  endif
+
+   /* The following two API calls simply set fields in png_struct, so it is safe
+    * to do them now even though error handling is not yet set up.
+    */
+#  ifdef PNG_USER_MEM_SUPPORTED
+      png_set_mem_fn(&create_struct, mem_ptr, malloc_fn, free_fn);
+#  else
+      PNG_UNUSED(mem_ptr)
+      PNG_UNUSED(malloc_fn)
+      PNG_UNUSED(free_fn)
+#  endif
+
+   /* (*error_fn) can return control to the caller after the error_ptr is set,
+    * this will result in a memory leak unless the error_fn does something
+    * extremely sophisticated.  The design lacks merit but is implicit in the
+    * API.
+    */
+   png_set_error_fn(&create_struct, error_ptr, error_fn, warn_fn);
+
+#  ifdef PNG_SETJMP_SUPPORTED
+      if (!setjmp(create_jmp_buf))
+      {
+         /* Temporarily fake out the longjmp information until we have
+          * successfully completed this function.  This only works if we have
+          * setjmp() support compiled in, but it is safe - this stuff should
+          * never happen.
+          */
+         create_struct.jmp_buf_ptr = &create_jmp_buf;
+         create_struct.jmp_buf_size = 0; /*stack allocation*/
+         create_struct.longjmp_fn = longjmp;
+#  else
+      {
+#  endif
+         /* Call the general version checker (shared with read and write code):
+          */
+         if (png_user_version_check(&create_struct, user_png_ver) != 0)
+         {
+            png_structrp png_ptr = png_voidcast(png_structrp,
+               png_malloc_warn(&create_struct, (sizeof *png_ptr)));
+
+            if (png_ptr != NULL)
+            {
+               /* png_ptr->zstream holds a back-pointer to the png_struct, so
+                * this can only be done now:
+                */
+               create_struct.zstream.zalloc = png_zalloc;
+               create_struct.zstream.zfree = png_zfree;
+               create_struct.zstream.opaque = png_ptr;
+
+#              ifdef PNG_SETJMP_SUPPORTED
+                  /* Eliminate the local error handling: */
+                  create_struct.jmp_buf_ptr = NULL;
+                  create_struct.jmp_buf_size = 0;
+                  create_struct.longjmp_fn = 0;
+#              endif
+
+               *png_ptr = create_struct;
+
+               /* This is the successful return point */
+               return png_ptr;
+            }
+         }
+      }
+
+   /* A longjmp because of a bug in the application storage allocator or a
+    * simple failure to allocate the png_struct.
+    */
+   return NULL;
+}
+
+/* Allocate the memory for an info_struct for the application. */
 PNG_FUNCTION(png_infop,PNGAPI
-png_create_info_struct,(png_structp png_ptr),PNG_ALLOCATED)
+png_create_info_struct,(png_const_structrp png_ptr),PNG_ALLOCATED)
 {
-   png_infop info_ptr;
+   png_inforp info_ptr;
 
    png_debug(1, "in png_create_info_struct");
 
    if (png_ptr == NULL)
-      return (NULL);
+      return NULL;
+
+   /* Use the internal API that does not (or at least should not) error out, so
+    * that this call always returns ok.  The application typically sets up the
+    * error handling *after* creating the info_struct because this is the way it
+    * has always been done in 'example.c'.
+    */
+   info_ptr = png_voidcast(png_inforp, png_malloc_base(png_ptr,
+      (sizeof *info_ptr)));
 
-#ifdef PNG_USER_MEM_SUPPORTED
-   info_ptr = (png_infop)png_create_struct_2(PNG_STRUCT_INFO,
-      png_ptr->malloc_fn, png_ptr->mem_ptr);
-#else
-   info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO);
-#endif
    if (info_ptr != NULL)
-      png_info_init_3(&info_ptr, png_sizeof(png_info));
+      memset(info_ptr, 0, (sizeof *info_ptr));
 
-   return (info_ptr);
+   return info_ptr;
 }
 
 /* This function frees the memory associated with a single info struct.
  * Normally, one would use either png_destroy_read_struct() or
  * png_destroy_write_struct() to free an info struct, but this may be
- * useful for some applications.
+ * useful for some applications.  From libpng 1.6.0 this function is also used
+ * internally to implement the png_info release part of the 'struct' destroy
+ * APIs.  This ensures that all possible approaches free the same data (all of
+ * it).
  */
 void PNGAPI
-png_destroy_info_struct(png_structp png_ptr, png_infopp info_ptr_ptr)
+png_destroy_info_struct(png_const_structrp png_ptr, png_infopp info_ptr_ptr)
 {
-   png_infop info_ptr = NULL;
+   png_inforp info_ptr = NULL;
 
    png_debug(1, "in png_destroy_info_struct");
 
@@ -268,46 +372,57 @@ png_destroy_info_struct(png_structp png_ptr, png_infopp info_ptr_ptr)
 
    if (info_ptr != NULL)
    {
-      png_info_destroy(png_ptr, info_ptr);
-
-#ifdef PNG_USER_MEM_SUPPORTED
-      png_destroy_struct_2((png_voidp)info_ptr, png_ptr->free_fn,
-          png_ptr->mem_ptr);
-#else
-      png_destroy_struct((png_voidp)info_ptr);
-#endif
+      /* Do this first in case of an error below; if the app implements its own
+       * memory management this can lead to png_free calling png_error, which
+       * will abort this routine and return control to the app error handler.
+       * An infinite loop may result if it then tries to free the same info
+       * ptr.
+       */
       *info_ptr_ptr = NULL;
+
+      png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
+      memset(info_ptr, 0, (sizeof *info_ptr));
+      png_free(png_ptr, info_ptr);
    }
 }
 
 /* Initialize the info structure.  This is now an internal function (0.89)
  * and applications using it are urged to use png_create_info_struct()
- * instead.
+ * instead.  Use deprecated in 1.6.0, internal use removed (used internally it
+ * is just a memset).
+ *
+ * NOTE: it is almost inconceivable that this API is used because it bypasses
+ * the user-memory mechanism and the user error handling/warning mechanisms in
+ * those cases where it does anything other than a memset.
  */
-
-void PNGAPI
-png_info_init_3(png_infopp ptr_ptr, png_size_t png_info_struct_size)
+PNG_FUNCTION(void,PNGAPI
+png_info_init_3,(png_infopp ptr_ptr, png_size_t png_info_struct_size),
+   PNG_DEPRECATED)
 {
-   png_infop info_ptr = *ptr_ptr;
+   png_inforp info_ptr = *ptr_ptr;
 
    png_debug(1, "in png_info_init_3");
 
    if (info_ptr == NULL)
       return;
 
-   if (png_sizeof(png_info) > png_info_struct_size)
+   if ((sizeof (png_info)) > png_info_struct_size)
    {
-      png_destroy_struct(info_ptr);
-      info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO);
+      *ptr_ptr = NULL;
+      /* The following line is why this API should not be used: */
+      free(info_ptr);
+      info_ptr = png_voidcast(png_inforp, png_malloc_base(NULL,
+         (sizeof *info_ptr)));
       *ptr_ptr = info_ptr;
    }
 
    /* Set everything to 0 */
-   png_memset(info_ptr, 0, png_sizeof(png_info));
+   memset(info_ptr, 0, (sizeof *info_ptr));
 }
 
+/* The following API is not called internally */
 void PNGAPI
-png_data_freer(png_structp png_ptr, png_infop info_ptr,
+png_data_freer(png_const_structrp png_ptr, png_inforp info_ptr,
    int freer, png_uint_32 mask)
 {
    png_debug(1, "in png_data_freer");
@@ -322,12 +437,11 @@ png_data_freer(png_structp png_ptr, png_infop info_ptr,
       info_ptr->free_me &= ~mask;
 
    else
-      png_warning(png_ptr,
-         "Unknown freer parameter in png_data_freer");
+      png_error(png_ptr, "Unknown freer parameter in png_data_freer");
 }
 
 void PNGAPI
-png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
+png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,
    int num)
 {
    png_debug(1, "in png_free_data");
@@ -337,42 +451,43 @@ png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
 
 #ifdef PNG_TEXT_SUPPORTED
    /* Free text item num or (if num == -1) all text items */
-   if ((mask & PNG_FREE_TEXT) & info_ptr->free_me)
+   if (info_ptr->text != 0 &&
+       ((mask & PNG_FREE_TEXT) & info_ptr->free_me) != 0)
    {
       if (num != -1)
       {
-         if (info_ptr->text && info_ptr->text[num].key)
-         {
-            png_free(png_ptr, info_ptr->text[num].key);
-            info_ptr->text[num].key = NULL;
-         }
+         png_free(png_ptr, info_ptr->text[num].key);
+         info_ptr->text[num].key = NULL;
       }
 
       else
       {
          int i;
+
          for (i = 0; i < info_ptr->num_text; i++)
-             png_free_data(png_ptr, info_ptr, PNG_FREE_TEXT, i);
+            png_free(png_ptr, info_ptr->text[i].key);
+
          png_free(png_ptr, info_ptr->text);
          info_ptr->text = NULL;
-         info_ptr->num_text=0;
+         info_ptr->num_text = 0;
       }
    }
 #endif
 
 #ifdef PNG_tRNS_SUPPORTED
    /* Free any tRNS entry */
-   if ((mask & PNG_FREE_TRNS) & info_ptr->free_me)
+   if (((mask & PNG_FREE_TRNS) & info_ptr->free_me) != 0)
    {
+      info_ptr->valid &= ~PNG_INFO_tRNS;
       png_free(png_ptr, info_ptr->trans_alpha);
       info_ptr->trans_alpha = NULL;
-      info_ptr->valid &= ~PNG_INFO_tRNS;
+      info_ptr->num_trans = 0;
    }
 #endif
 
 #ifdef PNG_sCAL_SUPPORTED
    /* Free any sCAL entry */
-   if ((mask & PNG_FREE_SCAL) & info_ptr->free_me)
+   if (((mask & PNG_FREE_SCAL) & info_ptr->free_me) != 0)
    {
       png_free(png_ptr, info_ptr->scal_s_width);
       png_free(png_ptr, info_ptr->scal_s_height);
@@ -384,20 +499,20 @@ png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
 
 #ifdef PNG_pCAL_SUPPORTED
    /* Free any pCAL entry */
-   if ((mask & PNG_FREE_PCAL) & info_ptr->free_me)
+   if (((mask & PNG_FREE_PCAL) & info_ptr->free_me) != 0)
    {
       png_free(png_ptr, info_ptr->pcal_purpose);
       png_free(png_ptr, info_ptr->pcal_units);
       info_ptr->pcal_purpose = NULL;
       info_ptr->pcal_units = NULL;
+
       if (info_ptr->pcal_params != NULL)
          {
             int i;
-            for (i = 0; i < (int)info_ptr->pcal_nparams; i++)
-            {
+
+            for (i = 0; i < info_ptr->pcal_nparams; i++)
                png_free(png_ptr, info_ptr->pcal_params[i]);
-               info_ptr->pcal_params[i] = NULL;
-            }
+
             png_free(png_ptr, info_ptr->pcal_params);
             info_ptr->pcal_params = NULL;
          }
@@ -406,8 +521,8 @@ png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
 #endif
 
 #ifdef PNG_iCCP_SUPPORTED
-   /* Free any iCCP entry */
-   if ((mask & PNG_FREE_ICCP) & info_ptr->free_me)
+   /* Free any profile entry */
+   if (((mask & PNG_FREE_ICCP) & info_ptr->free_me) != 0)
    {
       png_free(png_ptr, info_ptr->iccp_name);
       png_free(png_ptr, info_ptr->iccp_profile);
@@ -419,74 +534,62 @@ png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
 
 #ifdef PNG_sPLT_SUPPORTED
    /* Free a given sPLT entry, or (if num == -1) all sPLT entries */
-   if ((mask & PNG_FREE_SPLT) & info_ptr->free_me)
+   if (info_ptr->splt_palettes != 0 &&
+       ((mask & PNG_FREE_SPLT) & info_ptr->free_me) != 0)
    {
       if (num != -1)
       {
-         if (info_ptr->splt_palettes)
-         {
-            png_free(png_ptr, info_ptr->splt_palettes[num].name);
-            png_free(png_ptr, info_ptr->splt_palettes[num].entries);
-            info_ptr->splt_palettes[num].name = NULL;
-            info_ptr->splt_palettes[num].entries = NULL;
-         }
+         png_free(png_ptr, info_ptr->splt_palettes[num].name);
+         png_free(png_ptr, info_ptr->splt_palettes[num].entries);
+         info_ptr->splt_palettes[num].name = NULL;
+         info_ptr->splt_palettes[num].entries = NULL;
       }
 
       else
       {
-         if (info_ptr->splt_palettes_num)
-         {
-            int i;
-            for (i = 0; i < (int)info_ptr->splt_palettes_num; i++)
-               png_free_data(png_ptr, info_ptr, PNG_FREE_SPLT, i);
+         int i;
 
-            png_free(png_ptr, info_ptr->splt_palettes);
-            info_ptr->splt_palettes = NULL;
-            info_ptr->splt_palettes_num = 0;
+         for (i = 0; i < info_ptr->splt_palettes_num; i++)
+         {
+            png_free(png_ptr, info_ptr->splt_palettes[i].name);
+            png_free(png_ptr, info_ptr->splt_palettes[i].entries);
          }
+
+         png_free(png_ptr, info_ptr->splt_palettes);
+         info_ptr->splt_palettes = NULL;
+         info_ptr->splt_palettes_num = 0;
          info_ptr->valid &= ~PNG_INFO_sPLT;
       }
    }
 #endif
 
-#ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
-   if (png_ptr->unknown_chunk.data)
-   {
-      png_free(png_ptr, png_ptr->unknown_chunk.data);
-      png_ptr->unknown_chunk.data = NULL;
-   }
-
-   if ((mask & PNG_FREE_UNKN) & info_ptr->free_me)
+#ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
+   if (info_ptr->unknown_chunks != 0 &&
+       ((mask & PNG_FREE_UNKN) & info_ptr->free_me) != 0)
    {
       if (num != -1)
       {
-          if (info_ptr->unknown_chunks)
-          {
-             png_free(png_ptr, info_ptr->unknown_chunks[num].data);
-             info_ptr->unknown_chunks[num].data = NULL;
-          }
+          png_free(png_ptr, info_ptr->unknown_chunks[num].data);
+          info_ptr->unknown_chunks[num].data = NULL;
       }
 
       else
       {
          int i;
 
-         if (info_ptr->unknown_chunks_num)
-         {
-            for (i = 0; i < info_ptr->unknown_chunks_num; i++)
-               png_free_data(png_ptr, info_ptr, PNG_FREE_UNKN, i);
+         for (i = 0; i < info_ptr->unknown_chunks_num; i++)
+            png_free(png_ptr, info_ptr->unknown_chunks[i].data);
 
-            png_free(png_ptr, info_ptr->unknown_chunks);
-            info_ptr->unknown_chunks = NULL;
-            info_ptr->unknown_chunks_num = 0;
-         }
+         png_free(png_ptr, info_ptr->unknown_chunks);
+         info_ptr->unknown_chunks = NULL;
+         info_ptr->unknown_chunks_num = 0;
       }
    }
 #endif
 
 #ifdef PNG_hIST_SUPPORTED
    /* Free any hIST entry */
-   if ((mask & PNG_FREE_HIST)  & info_ptr->free_me)
+   if (((mask & PNG_FREE_HIST) & info_ptr->free_me) != 0)
    {
       png_free(png_ptr, info_ptr->hist);
       info_ptr->hist = NULL;
@@ -495,9 +598,9 @@ png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
 #endif
 
    /* Free any PLTE entry that was internally allocated */
-   if ((mask & PNG_FREE_PLTE) & info_ptr->free_me)
+   if (((mask & PNG_FREE_PLTE) & info_ptr->free_me) != 0)
    {
-      png_zfree(png_ptr, info_ptr->palette);
+      png_free(png_ptr, info_ptr->palette);
       info_ptr->palette = NULL;
       info_ptr->valid &= ~PNG_INFO_PLTE;
       info_ptr->num_palette = 0;
@@ -505,16 +608,14 @@ png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
 
 #ifdef PNG_INFO_IMAGE_SUPPORTED
    /* Free any image bits attached to the info structure */
-   if ((mask & PNG_FREE_ROWS) & info_ptr->free_me)
+   if (((mask & PNG_FREE_ROWS) & info_ptr->free_me) != 0)
    {
-      if (info_ptr->row_pointers)
+      if (info_ptr->row_pointers != 0)
       {
-         int row;
-         for (row = 0; row < (int)info_ptr->height; row++)
-         {
+         png_uint_32 row;
+         for (row = 0; row < info_ptr->height; row++)
             png_free(png_ptr, info_ptr->row_pointers[row]);
-            info_ptr->row_pointers[row] = NULL;
-         }
+
          png_free(png_ptr, info_ptr->row_pointers);
          info_ptr->row_pointers = NULL;
       }
@@ -527,37 +628,14 @@ png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
 
    info_ptr->free_me &= ~mask;
 }
-
-/* This is an internal routine to free any memory that the info struct is
- * pointing to before re-using it or freeing the struct itself.  Recall
- * that png_free() checks for NULL pointers for us.
- */
-void /* PRIVATE */
-png_info_destroy(png_structp png_ptr, png_infop info_ptr)
-{
-   png_debug(1, "in png_info_destroy");
-
-   png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
-
-#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
-   if (png_ptr->num_chunk_list)
-   {
-      png_free(png_ptr, png_ptr->chunk_list);
-      png_ptr->chunk_list = NULL;
-      png_ptr->num_chunk_list = 0;
-   }
-#endif
-
-   png_info_init_3(&info_ptr, png_sizeof(png_info));
-}
-#endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
+#endif /* READ || WRITE */
 
 /* This function returns a pointer to the io_ptr associated with the user
  * functions.  The application should free any memory associated with this
  * pointer before png_write_destroy() or png_read_destroy() are called.
  */
 png_voidp PNGAPI
-png_get_io_ptr(png_structp png_ptr)
+png_get_io_ptr(png_const_structrp png_ptr)
 {
    if (png_ptr == NULL)
       return (NULL);
@@ -574,7 +652,7 @@ png_get_io_ptr(png_structp png_ptr)
  * function of your own because "FILE *" isn't necessarily available.
  */
 void PNGAPI
-png_init_io(png_structp png_ptr, png_FILE_p fp)
+png_init_io(png_structrp png_ptr, png_FILE_p fp)
 {
    png_debug(1, "in png_init_io");
 
@@ -585,42 +663,52 @@ png_init_io(png_structp png_ptr, png_FILE_p fp)
 }
 #  endif
 
+#  ifdef PNG_SAVE_INT_32_SUPPORTED
+/* The png_save_int_32 function assumes integers are stored in two's
+ * complement format.  If this isn't the case, then this routine needs to
+ * be modified to write data in two's complement format.  Note that,
+ * the following works correctly even if png_int_32 has more than 32 bits
+ * (compare the more complex code required on read for sign extension.)
+ */
+void PNGAPI
+png_save_int_32(png_bytep buf, png_int_32 i)
+{
+   buf[0] = (png_byte)((i >> 24) & 0xff);
+   buf[1] = (png_byte)((i >> 16) & 0xff);
+   buf[2] = (png_byte)((i >> 8) & 0xff);
+   buf[3] = (png_byte)(i & 0xff);
+}
+#  endif
+
 #  ifdef PNG_TIME_RFC1123_SUPPORTED
 /* Convert the supplied time into an RFC 1123 string suitable for use in
  * a "Creation Time" or other text-based time string.
  */
-png_const_charp PNGAPI
-png_convert_to_rfc1123(png_structp png_ptr, png_const_timep ptime)
+int PNGAPI
+png_convert_to_rfc1123_buffer(char out[29], png_const_timep ptime)
 {
    static PNG_CONST char short_months[12][4] =
         {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
          "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
 
-   if (png_ptr == NULL)
-      return (NULL);
+   if (out == NULL)
+      return 0;
 
    if (ptime->year > 9999 /* RFC1123 limitation */ ||
        ptime->month == 0    ||  ptime->month > 12  ||
        ptime->day   == 0    ||  ptime->day   > 31  ||
        ptime->hour  > 23    ||  ptime->minute > 59 ||
        ptime->second > 60)
-   {
-      png_warning(png_ptr, "Ignoring invalid time value");
-      return (NULL);
-   }
+      return 0;
 
    {
       size_t pos = 0;
       char number_buf[5]; /* enough for a four-digit year */
 
-#     define APPEND_STRING(string)\
-         pos = png_safecat(png_ptr->time_buffer, sizeof png_ptr->time_buffer,\
-            pos, (string))
+#     define APPEND_STRING(string) pos = png_safecat(out, 29, pos, (string))
 #     define APPEND_NUMBER(format, value)\
          APPEND_STRING(PNG_FORMAT_NUMBER(number_buf, format, (value)))
-#     define APPEND(ch)\
-         if (pos < (sizeof png_ptr->time_buffer)-1)\
-            png_ptr->time_buffer[pos++] = (ch)
+#     define APPEND(ch) if (pos < 28) out[pos++] = (ch)
 
       APPEND_NUMBER(PNG_NUMBER_FORMAT_u, (unsigned)ptime->day);
       APPEND(' ');
@@ -640,14 +728,37 @@ png_convert_to_rfc1123(png_structp png_ptr, png_const_timep ptime)
 #     undef APPEND_STRING
    }
 
-   return png_ptr->time_buffer;
+   return 1;
+}
+
+#    if PNG_LIBPNG_VER < 10700
+/* To do: remove the following from libpng-1.7 */
+/* Original API that uses a private buffer in png_struct.
+ * Deprecated because it causes png_struct to carry a spurious temporary
+ * buffer (png_struct::time_buffer), better to have the caller pass this in.
+ */
+png_const_charp PNGAPI
+png_convert_to_rfc1123(png_structrp png_ptr, png_const_timep ptime)
+{
+   if (png_ptr != NULL)
+   {
+      /* The only failure above if png_ptr != NULL is from an invalid ptime */
+      if (png_convert_to_rfc1123_buffer(png_ptr->time_buffer, ptime) == 0)
+         png_warning(png_ptr, "Ignoring invalid time value");
+
+      else
+         return png_ptr->time_buffer;
+   }
+
+   return NULL;
 }
-#  endif /* PNG_TIME_RFC1123_SUPPORTED */
+#    endif /* LIBPNG_VER < 10700 */
+#  endif /* TIME_RFC1123 */
 
-#endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
+#endif /* READ || WRITE */
 
 png_const_charp PNGAPI
-png_get_copyright(png_const_structp png_ptr)
+png_get_copyright(png_const_structrp png_ptr)
 {
    PNG_UNUSED(png_ptr)  /* Silence compiler warning about unused png_ptr */
 #ifdef PNG_STRING_COPYRIGHT
@@ -655,14 +766,14 @@ png_get_copyright(png_const_structp png_ptr)
 #else
 #  ifdef __STDC__
    return PNG_STRING_NEWLINE \
-     "libpng version 1.5.10 - March 29, 2012" PNG_STRING_NEWLINE \
-     "Copyright (c) 1998-2011 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \
+     "libpng version 1.6.17 - March 26, 2015" PNG_STRING_NEWLINE \
+     "Copyright (c) 1998-2015 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \
      "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
      "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
      PNG_STRING_NEWLINE;
 #  else
-      return "libpng version 1.5.10 - March 29, 2012\
-      Copyright (c) 1998-2011 Glenn Randers-Pehrson\
+      return "libpng version 1.6.17 - March 26, 2015\
+      Copyright (c) 1998-2015 Glenn Randers-Pehrson\
       Copyright (c) 1996-1997 Andreas Dilger\
       Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
 #  endif
@@ -678,14 +789,14 @@ png_get_copyright(png_const_structp png_ptr)
  * it is guaranteed that png.c uses the correct version of png.h.
  */
 png_const_charp PNGAPI
-png_get_libpng_ver(png_const_structp png_ptr)
+png_get_libpng_ver(png_const_structrp png_ptr)
 {
    /* Version of *.c files used when building libpng */
    return png_get_header_ver(png_ptr);
 }
 
 png_const_charp PNGAPI
-png_get_header_ver(png_const_structp png_ptr)
+png_get_header_ver(png_const_structrp png_ptr)
 {
    /* Version of *.h files used when building libpng */
    PNG_UNUSED(png_ptr)  /* Silence compiler warning about unused png_ptr */
@@ -693,7 +804,7 @@ png_get_header_ver(png_const_structp png_ptr)
 }
 
 png_const_charp PNGAPI
-png_get_header_version(png_const_structp png_ptr)
+png_get_header_version(png_const_structrp png_ptr)
 {
    /* Returns longer string containing both version and date */
    PNG_UNUSED(png_ptr)  /* Silence compiler warning about unused png_ptr */
@@ -708,55 +819,122 @@ png_get_header_version(png_const_structp png_ptr)
 #endif
 }
 
-#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+#ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
+/* NOTE: this routine is not used internally! */
+/* Build a grayscale palette.  Palette is assumed to be 1 << bit_depth
+ * large of png_color.  This lets grayscale images be treated as
+ * paletted.  Most useful for gamma correction and simplification
+ * of code.  This API is not used internally.
+ */
+void PNGAPI
+png_build_grayscale_palette(int bit_depth, png_colorp palette)
+{
+   int num_palette;
+   int color_inc;
+   int i;
+   int v;
+
+   png_debug(1, "in png_do_build_grayscale_palette");
+
+   if (palette == NULL)
+      return;
+
+   switch (bit_depth)
+   {
+      case 1:
+         num_palette = 2;
+         color_inc = 0xff;
+         break;
+
+      case 2:
+         num_palette = 4;
+         color_inc = 0x55;
+         break;
+
+      case 4:
+         num_palette = 16;
+         color_inc = 0x11;
+         break;
+
+      case 8:
+         num_palette = 256;
+         color_inc = 1;
+         break;
+
+      default:
+         num_palette = 0;
+         color_inc = 0;
+         break;
+   }
+
+   for (i = 0, v = 0; i < num_palette; i++, v += color_inc)
+   {
+      palette[i].red = (png_byte)(v & 0xff);
+      palette[i].green = (png_byte)(v & 0xff);
+      palette[i].blue = (png_byte)(v & 0xff);
+   }
+}
+#endif
+
+#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
 int PNGAPI
-png_handle_as_unknown(png_structp png_ptr, png_const_bytep chunk_name)
+png_handle_as_unknown(png_const_structrp png_ptr, png_const_bytep chunk_name)
 {
    /* Check chunk_name and return "keep" value if it's on the list, else 0 */
    png_const_bytep p, p_end;
 
-   if (png_ptr == NULL || chunk_name == NULL || png_ptr->num_chunk_list <= 0)
+   if (png_ptr == NULL || chunk_name == NULL || png_ptr->num_chunk_list == 0)
       return PNG_HANDLE_CHUNK_AS_DEFAULT;
 
    p_end = png_ptr->chunk_list;
    p = p_end + png_ptr->num_chunk_list*5; /* beyond end */
 
    /* The code is the fifth byte after each four byte string.  Historically this
-    * code was always searched from the end of the list, so it should continue
-    * to do so in case there are duplicated entries.
+    * code was always searched from the end of the list, this is no longer
+    * necessary because the 'set' routine handles duplicate entries correcty.
     */
    do /* num_chunk_list > 0, so at least one */
    {
       p -= 5;
-      if (!png_memcmp(chunk_name, p, 4))
+
+      if (memcmp(chunk_name, p, 4) == 0)
          return p[4];
    }
    while (p > p_end);
 
+   /* This means that known chunks should be processed and unknown chunks should
+    * be handled according to the value of png_ptr->unknown_default; this can be
+    * confusing because, as a result, there are two levels of defaulting for
+    * unknown chunks.
+    */
    return PNG_HANDLE_CHUNK_AS_DEFAULT;
 }
 
+#if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) ||\
+   defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
 int /* PRIVATE */
-png_chunk_unknown_handling(png_structp png_ptr, png_uint_32 chunk_name)
+png_chunk_unknown_handling(png_const_structrp png_ptr, png_uint_32 chunk_name)
 {
    png_byte chunk_string[5];
 
    PNG_CSTRING_FROM_CHUNK(chunk_string, chunk_name);
    return png_handle_as_unknown(png_ptr, chunk_string);
 }
-#endif
+#endif /* READ_UNKNOWN_CHUNKS || HANDLE_AS_UNKNOWN */
+#endif /* SET_UNKNOWN_CHUNKS */
 
 #ifdef PNG_READ_SUPPORTED
 /* This function, added to libpng-1.0.6g, is untested. */
 int PNGAPI
-png_reset_zstream(png_structp png_ptr)
+png_reset_zstream(png_structrp png_ptr)
 {
    if (png_ptr == NULL)
       return Z_STREAM_ERROR;
 
+   /* WARNING: this resets the window bits to the maximum! */
    return (inflateReset(&png_ptr->zstream));
 }
-#endif /* PNG_READ_SUPPORTED */
+#endif /* READ */
 
 /* This function was added to libpng-1.0.7 */
 png_uint_32 PNGAPI
@@ -766,126 +944,291 @@ png_access_version_number(void)
    return((png_uint_32)PNG_LIBPNG_VER);
 }
 
+#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
+/* Ensure that png_ptr->zstream.msg holds some appropriate error message string.
+ * If it doesn't 'ret' is used to set it to something appropriate, even in cases
+ * like Z_OK or Z_STREAM_END where the error code is apparently a success code.
+ */
+void /* PRIVATE */
+png_zstream_error(png_structrp png_ptr, int ret)
+{
+   /* Translate 'ret' into an appropriate error string, priority is given to the
+    * one in zstream if set.  This always returns a string, even in cases like
+    * Z_OK or Z_STREAM_END where the error code is a success code.
+    */
+   if (png_ptr->zstream.msg == NULL) switch (ret)
+   {
+      default:
+      case Z_OK:
+         png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected zlib return code");
+         break;
+
+      case Z_STREAM_END:
+         /* Normal exit */
+         png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected end of LZ stream");
+         break;
 
+      case Z_NEED_DICT:
+         /* This means the deflate stream did not have a dictionary; this
+          * indicates a bogus PNG.
+          */
+         png_ptr->zstream.msg = PNGZ_MSG_CAST("missing LZ dictionary");
+         break;
+
+      case Z_ERRNO:
+         /* gz APIs only: should not happen */
+         png_ptr->zstream.msg = PNGZ_MSG_CAST("zlib IO error");
+         break;
+
+      case Z_STREAM_ERROR:
+         /* internal libpng error */
+         png_ptr->zstream.msg = PNGZ_MSG_CAST("bad parameters to zlib");
+         break;
+
+      case Z_DATA_ERROR:
+         png_ptr->zstream.msg = PNGZ_MSG_CAST("damaged LZ stream");
+         break;
+
+      case Z_MEM_ERROR:
+         png_ptr->zstream.msg = PNGZ_MSG_CAST("insufficient memory");
+         break;
+
+      case Z_BUF_ERROR:
+         /* End of input or output; not a problem if the caller is doing
+          * incremental read or write.
+          */
+         png_ptr->zstream.msg = PNGZ_MSG_CAST("truncated");
+         break;
+
+      case Z_VERSION_ERROR:
+         png_ptr->zstream.msg = PNGZ_MSG_CAST("unsupported zlib version");
+         break;
+
+      case PNG_UNEXPECTED_ZLIB_RETURN:
+         /* Compile errors here mean that zlib now uses the value co-opted in
+          * pngpriv.h for PNG_UNEXPECTED_ZLIB_RETURN; update the switch above
+          * and change pngpriv.h.  Note that this message is "... return",
+          * whereas the default/Z_OK one is "... return code".
+          */
+         png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected zlib return");
+         break;
+   }
+}
 
-#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
 /* png_convert_size: a PNGAPI but no longer in png.h, so deleted
  * at libpng 1.5.5!
  */
 
 /* Added at libpng version 1.2.34 and 1.4.0 (moved from pngset.c) */
-#  ifdef PNG_CHECK_cHRM_SUPPORTED
-
-int /* PRIVATE */
-png_check_cHRM_fixed(png_structp png_ptr,
-   png_fixed_point white_x, png_fixed_point white_y, png_fixed_point red_x,
-   png_fixed_point red_y, png_fixed_point green_x, png_fixed_point green_y,
-   png_fixed_point blue_x, png_fixed_point blue_y)
+#ifdef PNG_GAMMA_SUPPORTED /* always set if COLORSPACE */
+static int
+png_colorspace_check_gamma(png_const_structrp png_ptr,
+   png_colorspacerp colorspace, png_fixed_point gAMA, int from)
+   /* This is called to check a new gamma value against an existing one.  The
+    * routine returns false if the new gamma value should not be written.
+    *
+    * 'from' says where the new gamma value comes from:
+    *
+    *    0: the new gamma value is the libpng estimate for an ICC profile
+    *    1: the new gamma value comes from a gAMA chunk
+    *    2: the new gamma value comes from an sRGB chunk
+    */
 {
-   int ret = 1;
-   unsigned long xy_hi,xy_lo,yx_hi,yx_lo;
+   png_fixed_point gtest;
 
-   png_debug(1, "in function png_check_cHRM_fixed");
+   if ((colorspace->flags & PNG_COLORSPACE_HAVE_GAMMA) != 0 &&
+      (png_muldiv(&gtest, colorspace->gamma, PNG_FP_1, gAMA) == 0  ||
+      png_gamma_significant(gtest) != 0))
+   {
+      /* Either this is an sRGB image, in which case the calculated gamma
+       * approximation should match, or this is an image with a profile and the
+       * value libpng calculates for the gamma of the profile does not match the
+       * value recorded in the file.  The former, sRGB, case is an error, the
+       * latter is just a warning.
+       */
+      if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0 || from == 2)
+      {
+         png_chunk_report(png_ptr, "gamma value does not match sRGB",
+            PNG_CHUNK_ERROR);
+         /* Do not overwrite an sRGB value */
+         return from == 2;
+      }
 
-   if (png_ptr == NULL)
-      return 0;
+      else /* sRGB tag not involved */
+      {
+         png_chunk_report(png_ptr, "gamma value does not match libpng estimate",
+            PNG_CHUNK_WARNING);
+         return from == 1;
+      }
+   }
+
+   return 1;
+}
 
-   /* (x,y,z) values are first limited to 0..100000 (PNG_FP_1), the white
-    * y must also be greater than 0.  To test for the upper limit calculate
-    * (PNG_FP_1-y) - x must be <= to this for z to be >= 0 (and the expression
-    * cannot overflow.)  At this point we know x and y are >= 0 and (x+y) is
-    * <= PNG_FP_1.  The previous test on PNG_MAX_UINT_31 is removed because it
-    * pointless (and it produces compiler warnings!)
+void /* PRIVATE */
+png_colorspace_set_gamma(png_const_structrp png_ptr,
+   png_colorspacerp colorspace, png_fixed_point gAMA)
+{
+   /* Changed in libpng-1.5.4 to limit the values to ensure overflow can't
+    * occur.  Since the fixed point representation is asymetrical it is
+    * possible for 1/gamma to overflow the limit of 21474 and this means the
+    * gamma value must be at least 5/100000 and hence at most 20000.0.  For
+    * safety the limits here are a little narrower.  The values are 0.00016 to
+    * 6250.0, which are truly ridiculous gamma values (and will produce
+    * displays that are all black or all white.)
+    *
+    * In 1.6.0 this test replaces the ones in pngrutil.c, in the gAMA chunk
+    * handling code, which only required the value to be >0.
     */
-   if (white_x < 0 || white_y <= 0 ||
-         red_x < 0 ||   red_y <  0 ||
-       green_x < 0 || green_y <  0 ||
-        blue_x < 0 ||  blue_y <  0)
-   {
-      png_warning(png_ptr,
-        "Ignoring attempt to set negative chromaticity value");
-      ret = 0;
-   }
-   /* And (x+y) must be <= PNG_FP_1 (so z is >= 0) */
-   if (white_x > PNG_FP_1 - white_y)
-   {
-      png_warning(png_ptr, "Invalid cHRM white point");
-      ret = 0;
-   }
+   png_const_charp errmsg;
 
-   if (red_x > PNG_FP_1 - red_y)
+   if (gAMA < 16 || gAMA > 625000000)
+      errmsg = "gamma value out of range";
+
+#  ifdef PNG_READ_gAMA_SUPPORTED
+      /* Allow the application to set the gamma value more than once */
+      else if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
+         (colorspace->flags & PNG_COLORSPACE_FROM_gAMA) != 0)
+         errmsg = "duplicate";
+#  endif
+
+   /* Do nothing if the colorspace is already invalid */
+   else if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
+      return;
+
+   else
    {
-      png_warning(png_ptr, "Invalid cHRM red point");
-      ret = 0;
+      if (png_colorspace_check_gamma(png_ptr, colorspace, gAMA,
+          1/*from gAMA*/) != 0)
+      {
+         /* Store this gamma value. */
+         colorspace->gamma = gAMA;
+         colorspace->flags |=
+            (PNG_COLORSPACE_HAVE_GAMMA | PNG_COLORSPACE_FROM_gAMA);
+      }
+
+      /* At present if the check_gamma test fails the gamma of the colorspace is
+       * not updated however the colorspace is not invalidated.  This
+       * corresponds to the case where the existing gamma comes from an sRGB
+       * chunk or profile.  An error message has already been output.
+       */
+      return;
    }
 
-   if (green_x > PNG_FP_1 - green_y)
+   /* Error exit - errmsg has been set. */
+   colorspace->flags |= PNG_COLORSPACE_INVALID;
+   png_chunk_report(png_ptr, errmsg, PNG_CHUNK_WRITE_ERROR);
+}
+
+void /* PRIVATE */
+png_colorspace_sync_info(png_const_structrp png_ptr, png_inforp info_ptr)
+{
+   if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
    {
-      png_warning(png_ptr, "Invalid cHRM green point");
-      ret = 0;
+      /* Everything is invalid */
+      info_ptr->valid &= ~(PNG_INFO_gAMA|PNG_INFO_cHRM|PNG_INFO_sRGB|
+         PNG_INFO_iCCP);
+
+#     ifdef PNG_COLORSPACE_SUPPORTED
+         /* Clean up the iCCP profile now if it won't be used. */
+         png_free_data(png_ptr, info_ptr, PNG_FREE_ICCP, -1/*not used*/);
+#     else
+         PNG_UNUSED(png_ptr)
+#     endif
    }
 
-   if (blue_x > PNG_FP_1 - blue_y)
+   else
    {
-      png_warning(png_ptr, "Invalid cHRM blue point");
-      ret = 0;
-   }
+#     ifdef PNG_COLORSPACE_SUPPORTED
+         /* Leave the INFO_iCCP flag set if the pngset.c code has already set
+          * it; this allows a PNG to contain a profile which matches sRGB and
+          * yet still have that profile retrievable by the application.
+          */
+         if ((info_ptr->colorspace.flags & PNG_COLORSPACE_MATCHES_sRGB) != 0)
+            info_ptr->valid |= PNG_INFO_sRGB;
 
-   png_64bit_product(green_x - red_x, blue_y - red_y, &xy_hi, &xy_lo);
-   png_64bit_product(green_y - red_y, blue_x - red_x, &yx_hi, &yx_lo);
+         else
+            info_ptr->valid &= ~PNG_INFO_sRGB;
 
-   if (xy_hi == yx_hi && xy_lo == yx_lo)
-   {
-      png_warning(png_ptr,
-         "Ignoring attempt to set cHRM RGB triangle with zero area");
-      ret = 0;
+         if ((info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
+            info_ptr->valid |= PNG_INFO_cHRM;
+
+         else
+            info_ptr->valid &= ~PNG_INFO_cHRM;
+#     endif
+
+      if ((info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) != 0)
+         info_ptr->valid |= PNG_INFO_gAMA;
+
+      else
+         info_ptr->valid &= ~PNG_INFO_gAMA;
    }
+}
 
-   return ret;
+#ifdef PNG_READ_SUPPORTED
+void /* PRIVATE */
+png_colorspace_sync(png_const_structrp png_ptr, png_inforp info_ptr)
+{
+   if (info_ptr == NULL) /* reduce code size; check here not in the caller */
+      return;
+
+   info_ptr->colorspace = png_ptr->colorspace;
+   png_colorspace_sync_info(png_ptr, info_ptr);
 }
-#  endif /* PNG_CHECK_cHRM_SUPPORTED */
+#endif
+#endif /* GAMMA */
 
-#ifdef PNG_cHRM_SUPPORTED
+#ifdef PNG_COLORSPACE_SUPPORTED
 /* Added at libpng-1.5.5 to support read and write of true CIEXYZ values for
  * cHRM, as opposed to using chromaticities.  These internal APIs return
  * non-zero on a parameter error.  The X, Y and Z values are required to be
  * positive and less than 1.0.
  */
-int png_xy_from_XYZ(png_xy *xy, png_XYZ XYZ)
+static int
+png_xy_from_XYZ(png_xy *xy, const png_XYZ *XYZ)
 {
    png_int_32 d, dwhite, whiteX, whiteY;
 
-   d = XYZ.redX + XYZ.redY + XYZ.redZ;
-   if (!png_muldiv(&xy->redx, XYZ.redX, PNG_FP_1, d)) return 1;
-   if (!png_muldiv(&xy->redy, XYZ.redY, PNG_FP_1, d)) return 1;
+   d = XYZ->red_X + XYZ->red_Y + XYZ->red_Z;
+   if (png_muldiv(&xy->redx, XYZ->red_X, PNG_FP_1, d) == 0)
+      return 1;
+   if (png_muldiv(&xy->redy, XYZ->red_Y, PNG_FP_1, d) == 0)
+      return 1;
    dwhite = d;
-   whiteX = XYZ.redX;
-   whiteY = XYZ.redY;
+   whiteX = XYZ->red_X;
+   whiteY = XYZ->red_Y;
 
-   d = XYZ.greenX + XYZ.greenY + XYZ.greenZ;
-   if (!png_muldiv(&xy->greenx, XYZ.greenX, PNG_FP_1, d)) return 1;
-   if (!png_muldiv(&xy->greeny, XYZ.greenY, PNG_FP_1, d)) return 1;
+   d = XYZ->green_X + XYZ->green_Y + XYZ->green_Z;
+   if (png_muldiv(&xy->greenx, XYZ->green_X, PNG_FP_1, d) == 0)
+      return 1;
+   if (png_muldiv(&xy->greeny, XYZ->green_Y, PNG_FP_1, d) == 0)
+      return 1;
    dwhite += d;
-   whiteX += XYZ.greenX;
-   whiteY += XYZ.greenY;
+   whiteX += XYZ->green_X;
+   whiteY += XYZ->green_Y;
 
-   d = XYZ.blueX + XYZ.blueY + XYZ.blueZ;
-   if (!png_muldiv(&xy->bluex, XYZ.blueX, PNG_FP_1, d)) return 1;
-   if (!png_muldiv(&xy->bluey, XYZ.blueY, PNG_FP_1, d)) return 1;
+   d = XYZ->blue_X + XYZ->blue_Y + XYZ->blue_Z;
+   if (png_muldiv(&xy->bluex, XYZ->blue_X, PNG_FP_1, d) == 0)
+      return 1;
+   if (png_muldiv(&xy->bluey, XYZ->blue_Y, PNG_FP_1, d) == 0)
+      return 1;
    dwhite += d;
-   whiteX += XYZ.blueX;
-   whiteY += XYZ.blueY;
+   whiteX += XYZ->blue_X;
+   whiteY += XYZ->blue_Y;
 
-   /* The reference white is simply the same of the end-point (X,Y,Z) vectors,
+   /* The reference white is simply the sum of the end-point (X,Y,Z) vectors,
     * thus:
     */
-   if (!png_muldiv(&xy->whitex, whiteX, PNG_FP_1, dwhite)) return 1;
-   if (!png_muldiv(&xy->whitey, whiteY, PNG_FP_1, dwhite)) return 1;
+   if (png_muldiv(&xy->whitex, whiteX, PNG_FP_1, dwhite) == 0)
+      return 1;
+   if (png_muldiv(&xy->whitey, whiteY, PNG_FP_1, dwhite) == 0)
+      return 1;
 
    return 0;
 }
 
-int png_XYZ_from_xy(png_XYZ *XYZ, png_xy xy)
+static int
+png_XYZ_from_xy(png_XYZ *XYZ, const png_xy *xy)
 {
    png_fixed_point red_inverse, green_inverse, blue_scale;
    png_fixed_point left, right, denominator;
@@ -894,14 +1237,14 @@ int png_XYZ_from_xy(png_XYZ *XYZ, png_xy xy)
     * have end points with 0 tristimulus values (these are impossible end
     * points, but they are used to cover the possible colors.)
     */
-   if (xy.redx < 0 || xy.redx > PNG_FP_1) return 1;
-   if (xy.redy < 0 || xy.redy > PNG_FP_1-xy.redx) return 1;
-   if (xy.greenx < 0 || xy.greenx > PNG_FP_1) return 1;
-   if (xy.greeny < 0 || xy.greeny > PNG_FP_1-xy.greenx) return 1;
-   if (xy.bluex < 0 || xy.bluex > PNG_FP_1) return 1;
-   if (xy.bluey < 0 || xy.bluey > PNG_FP_1-xy.bluex) return 1;
-   if (xy.whitex < 0 || xy.whitex > PNG_FP_1) return 1;
-   if (xy.whitey < 0 || xy.whitey > PNG_FP_1-xy.whitex) return 1;
+   if (xy->redx < 0 || xy->redx > PNG_FP_1) return 1;
+   if (xy->redy < 0 || xy->redy > PNG_FP_1-xy->redx) return 1;
+   if (xy->greenx < 0 || xy->greenx > PNG_FP_1) return 1;
+   if (xy->greeny < 0 || xy->greeny > PNG_FP_1-xy->greenx) return 1;
+   if (xy->bluex < 0 || xy->bluex > PNG_FP_1) return 1;
+   if (xy->bluey < 0 || xy->bluey > PNG_FP_1-xy->bluex) return 1;
+   if (xy->whitex < 0 || xy->whitex > PNG_FP_1) return 1;
+   if (xy->whitey < 0 || xy->whitey > PNG_FP_1-xy->whitex) return 1;
 
    /* The reverse calculation is more difficult because the original tristimulus
     * value had 9 independent values (red,green,blue)x(X,Y,Z) however only 8
@@ -969,14 +1312,14 @@ int png_XYZ_from_xy(png_XYZ *XYZ, png_xy xy)
     * and it is certain that it becomes unstable where the end points are close
     * together.
     *
-    * So this code uses the perhaps slighly less optimal but more understandable
-    * and totally obvious approach of calculating color-scale.
+    * So this code uses the perhaps slightly less optimal but more
+    * understandable and totally obvious approach of calculating color-scale.
     *
     * This algorithm depends on the precision in white-scale and that is
     * (1/white-y), so we can immediately see that as white-y approaches 0 the
     * accuracy inherent in the cHRM chunk drops off substantially.
     *
-    * libpng arithmetic: a simple invertion of the above equations
+    * libpng arithmetic: a simple inversion of the above equations
     * ------------------------------------------------------------
     *
     *    white_scale = 1/white-y
@@ -1082,91 +1425,1050 @@ int png_XYZ_from_xy(png_XYZ *XYZ, png_xy xy)
    /* By the argument, above overflow should be impossible here. The return
     * value of 2 indicates an internal error to the caller.
     */
-   if (!png_muldiv(&left, xy.greenx-xy.bluex, xy.redy - xy.bluey, 7)) return 2;
-   if (!png_muldiv(&right, xy.greeny-xy.bluey, xy.redx - xy.bluex, 7)) return 2;
+   if (png_muldiv(&left, xy->greenx-xy->bluex, xy->redy - xy->bluey, 7) == 0)
+      return 2;
+   if (png_muldiv(&right, xy->greeny-xy->bluey, xy->redx - xy->bluex, 7) == 0)
+      return 2;
    denominator = left - right;
 
    /* Now find the red numerator. */
-   if (!png_muldiv(&left, xy.greenx-xy.bluex, xy.whitey-xy.bluey, 7)) return 2;
-   if (!png_muldiv(&right, xy.greeny-xy.bluey, xy.whitex-xy.bluex, 7)) return 2;
+   if (png_muldiv(&left, xy->greenx-xy->bluex, xy->whitey-xy->bluey, 7) == 0)
+      return 2;
+   if (png_muldiv(&right, xy->greeny-xy->bluey, xy->whitex-xy->bluex, 7) == 0)
+      return 2;
 
    /* Overflow is possible here and it indicates an extreme set of PNG cHRM
     * chunk values.  This calculation actually returns the reciprocal of the
     * scale value because this allows us to delay the multiplication of white-y
     * into the denominator, which tends to produce a small number.
     */
-   if (!png_muldiv(&red_inverse, xy.whitey, denominator, left-right) ||
-       red_inverse <= xy.whitey /* r+g+b scales = white scale */)
+   if (png_muldiv(&red_inverse, xy->whitey, denominator, left-right) == 0 ||
+       red_inverse <= xy->whitey /* r+g+b scales = white scale */)
       return 1;
 
    /* Similarly for green_inverse: */
-   if (!png_muldiv(&left, xy.redy-xy.bluey, xy.whitex-xy.bluex, 7)) return 2;
-   if (!png_muldiv(&right, xy.redx-xy.bluex, xy.whitey-xy.bluey, 7)) return 2;
-   if (!png_muldiv(&green_inverse, xy.whitey, denominator, left-right) ||
-       green_inverse <= xy.whitey)
+   if (png_muldiv(&left, xy->redy-xy->bluey, xy->whitex-xy->bluex, 7) == 0)
+      return 2;
+   if (png_muldiv(&right, xy->redx-xy->bluex, xy->whitey-xy->bluey, 7) == 0)
+      return 2;
+   if (png_muldiv(&green_inverse, xy->whitey, denominator, left-right) == 0 ||
+       green_inverse <= xy->whitey)
       return 1;
 
    /* And the blue scale, the checks above guarantee this can't overflow but it
     * can still produce 0 for extreme cHRM values.
     */
-   blue_scale = png_reciprocal(xy.whitey) - png_reciprocal(red_inverse) -
-      png_reciprocal(green_inverse);
-   if (blue_scale <= 0) return 1;
+   blue_scale = png_reciprocal(xy->whitey) - png_reciprocal(red_inverse) -
+       png_reciprocal(green_inverse);
+   if (blue_scale <= 0)
+      return 1;
 
 
    /* And fill in the png_XYZ: */
-   if (!png_muldiv(&XYZ->redX, xy.redx, PNG_FP_1, red_inverse)) return 1;
-   if (!png_muldiv(&XYZ->redY, xy.redy, PNG_FP_1, red_inverse)) return 1;
-   if (!png_muldiv(&XYZ->redZ, PNG_FP_1 - xy.redx - xy.redy, PNG_FP_1,
-      red_inverse))
+   if (png_muldiv(&XYZ->red_X, xy->redx, PNG_FP_1, red_inverse) == 0)
+      return 1;
+   if (png_muldiv(&XYZ->red_Y, xy->redy, PNG_FP_1, red_inverse) == 0)
+      return 1;
+   if (png_muldiv(&XYZ->red_Z, PNG_FP_1 - xy->redx - xy->redy, PNG_FP_1,
+       red_inverse) == 0)
       return 1;
 
-   if (!png_muldiv(&XYZ->greenX, xy.greenx, PNG_FP_1, green_inverse)) return 1;
-   if (!png_muldiv(&XYZ->greenY, xy.greeny, PNG_FP_1, green_inverse)) return 1;
-   if (!png_muldiv(&XYZ->greenZ, PNG_FP_1 - xy.greenx - xy.greeny, PNG_FP_1,
-      green_inverse))
+   if (png_muldiv(&XYZ->green_X, xy->greenx, PNG_FP_1, green_inverse) == 0)
+      return 1;
+   if (png_muldiv(&XYZ->green_Y, xy->greeny, PNG_FP_1, green_inverse) == 0)
+      return 1;
+   if (png_muldiv(&XYZ->green_Z, PNG_FP_1 - xy->greenx - xy->greeny, PNG_FP_1,
+       green_inverse) == 0)
       return 1;
 
-   if (!png_muldiv(&XYZ->blueX, xy.bluex, blue_scale, PNG_FP_1)) return 1;
-   if (!png_muldiv(&XYZ->blueY, xy.bluey, blue_scale, PNG_FP_1)) return 1;
-   if (!png_muldiv(&XYZ->blueZ, PNG_FP_1 - xy.bluex - xy.bluey, blue_scale,
-      PNG_FP_1))
+   if (png_muldiv(&XYZ->blue_X, xy->bluex, blue_scale, PNG_FP_1) == 0)
+      return 1;
+   if (png_muldiv(&XYZ->blue_Y, xy->bluey, blue_scale, PNG_FP_1) == 0)
+      return 1;
+   if (png_muldiv(&XYZ->blue_Z, PNG_FP_1 - xy->bluex - xy->bluey, blue_scale,
+       PNG_FP_1) == 0)
       return 1;
 
    return 0; /*success*/
 }
 
-int png_XYZ_from_xy_checked(png_structp png_ptr, png_XYZ *XYZ, png_xy xy)
+static int
+png_XYZ_normalize(png_XYZ *XYZ)
 {
-   switch (png_XYZ_from_xy(XYZ, xy))
+   png_int_32 Y;
+
+   if (XYZ->red_Y < 0 || XYZ->green_Y < 0 || XYZ->blue_Y < 0 ||
+      XYZ->red_X < 0 || XYZ->green_X < 0 || XYZ->blue_X < 0 ||
+      XYZ->red_Z < 0 || XYZ->green_Z < 0 || XYZ->blue_Z < 0)
+      return 1;
+
+   /* Normalize by scaling so the sum of the end-point Y values is PNG_FP_1.
+    * IMPLEMENTATION NOTE: ANSI requires signed overflow not to occur, therefore
+    * relying on addition of two positive values producing a negative one is not
+    * safe.
+    */
+   Y = XYZ->red_Y;
+   if (0x7fffffff - Y < XYZ->green_X)
+      return 1;
+   Y += XYZ->green_Y;
+   if (0x7fffffff - Y < XYZ->blue_X)
+      return 1;
+   Y += XYZ->blue_Y;
+
+   if (Y != PNG_FP_1)
    {
-      case 0: /* success */
+      if (png_muldiv(&XYZ->red_X, XYZ->red_X, PNG_FP_1, Y) == 0)
+         return 1;
+      if (png_muldiv(&XYZ->red_Y, XYZ->red_Y, PNG_FP_1, Y) == 0)
+         return 1;
+      if (png_muldiv(&XYZ->red_Z, XYZ->red_Z, PNG_FP_1, Y) == 0)
+         return 1;
+
+      if (png_muldiv(&XYZ->green_X, XYZ->green_X, PNG_FP_1, Y) == 0)
+         return 1;
+      if (png_muldiv(&XYZ->green_Y, XYZ->green_Y, PNG_FP_1, Y) == 0)
+         return 1;
+      if (png_muldiv(&XYZ->green_Z, XYZ->green_Z, PNG_FP_1, Y) == 0)
          return 1;
 
+      if (png_muldiv(&XYZ->blue_X, XYZ->blue_X, PNG_FP_1, Y) == 0)
+         return 1;
+      if (png_muldiv(&XYZ->blue_Y, XYZ->blue_Y, PNG_FP_1, Y) == 0)
+         return 1;
+      if (png_muldiv(&XYZ->blue_Z, XYZ->blue_Z, PNG_FP_1, Y) == 0)
+         return 1;
+   }
+
+   return 0;
+}
+
+static int
+png_colorspace_endpoints_match(const png_xy *xy1, const png_xy *xy2, int delta)
+{
+   /* Allow an error of +/-0.01 (absolute value) on each chromaticity */
+   if (PNG_OUT_OF_RANGE(xy1->whitex, xy2->whitex,delta) ||
+       PNG_OUT_OF_RANGE(xy1->whitey, xy2->whitey,delta) ||
+       PNG_OUT_OF_RANGE(xy1->redx,   xy2->redx,  delta) ||
+       PNG_OUT_OF_RANGE(xy1->redy,   xy2->redy,  delta) ||
+       PNG_OUT_OF_RANGE(xy1->greenx, xy2->greenx,delta) ||
+       PNG_OUT_OF_RANGE(xy1->greeny, xy2->greeny,delta) ||
+       PNG_OUT_OF_RANGE(xy1->bluex,  xy2->bluex, delta) ||
+       PNG_OUT_OF_RANGE(xy1->bluey,  xy2->bluey, delta))
+      return 0;
+   return 1;
+}
+
+/* Added in libpng-1.6.0, a different check for the validity of a set of cHRM
+ * chunk chromaticities.  Earlier checks used to simply look for the overflow
+ * condition (where the determinant of the matrix to solve for XYZ ends up zero
+ * because the chromaticity values are not all distinct.)  Despite this it is
+ * theoretically possible to produce chromaticities that are apparently valid
+ * but that rapidly degrade to invalid, potentially crashing, sets because of
+ * arithmetic inaccuracies when calculations are performed on them.  The new
+ * check is to round-trip xy -> XYZ -> xy and then check that the result is
+ * within a small percentage of the original.
+ */
+static int
+png_colorspace_check_xy(png_XYZ *XYZ, const png_xy *xy)
+{
+   int result;
+   png_xy xy_test;
+
+   /* As a side-effect this routine also returns the XYZ endpoints. */
+   result = png_XYZ_from_xy(XYZ, xy);
+   if (result != 0)
+      return result;
+
+   result = png_xy_from_XYZ(&xy_test, XYZ);
+   if (result != 0)
+      return result;
+
+   if (png_colorspace_endpoints_match(xy, &xy_test,
+       5/*actually, the math is pretty accurate*/) != 0)
+      return 0;
+
+   /* Too much slip */
+   return 1;
+}
+
+/* This is the check going the other way.  The XYZ is modified to normalize it
+ * (another side-effect) and the xy chromaticities are returned.
+ */
+static int
+png_colorspace_check_XYZ(png_xy *xy, png_XYZ *XYZ)
+{
+   int result;
+   png_XYZ XYZtemp;
+
+   result = png_XYZ_normalize(XYZ);
+   if (result != 0)
+      return result;
+
+   result = png_xy_from_XYZ(xy, XYZ);
+   if (result != 0)
+      return result;
+
+   XYZtemp = *XYZ;
+   return png_colorspace_check_xy(&XYZtemp, xy);
+}
+
+/* Used to check for an endpoint match against sRGB */
+static const png_xy sRGB_xy = /* From ITU-R BT.709-3 */
+{
+   /* color      x       y */
+   /* red   */ 64000, 33000,
+   /* green */ 30000, 60000,
+   /* blue  */ 15000,  6000,
+   /* white */ 31270, 32900
+};
+
+static int
+png_colorspace_set_xy_and_XYZ(png_const_structrp png_ptr,
+   png_colorspacerp colorspace, const png_xy *xy, const png_XYZ *XYZ,
+   int preferred)
+{
+   if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
+      return 0;
+
+   /* The consistency check is performed on the chromaticities; this factors out
+    * variations because of the normalization (or not) of the end point Y
+    * values.
+    */
+   if (preferred < 2 &&
+       (colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
+   {
+      /* The end points must be reasonably close to any we already have.  The
+       * following allows an error of up to +/-.001
+       */
+      if (png_colorspace_endpoints_match(xy, &colorspace->end_points_xy,
+          100) == 0)
+      {
+         colorspace->flags |= PNG_COLORSPACE_INVALID;
+         png_benign_error(png_ptr, "inconsistent chromaticities");
+         return 0; /* failed */
+      }
+
+      /* Only overwrite with preferred values */
+      if (preferred == 0)
+         return 1; /* ok, but no change */
+   }
+
+   colorspace->end_points_xy = *xy;
+   colorspace->end_points_XYZ = *XYZ;
+   colorspace->flags |= PNG_COLORSPACE_HAVE_ENDPOINTS;
+
+   /* The end points are normally quoted to two decimal digits, so allow +/-0.01
+    * on this test.
+    */
+   if (png_colorspace_endpoints_match(xy, &sRGB_xy, 1000) != 0)
+      colorspace->flags |= PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB;
+
+   else
+      colorspace->flags &= PNG_COLORSPACE_CANCEL(
+         PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB);
+
+   return 2; /* ok and changed */
+}
+
+int /* PRIVATE */
+png_colorspace_set_chromaticities(png_const_structrp png_ptr,
+   png_colorspacerp colorspace, const png_xy *xy, int preferred)
+{
+   /* We must check the end points to ensure they are reasonable - in the past
+    * color management systems have crashed as a result of getting bogus
+    * colorant values, while this isn't the fault of libpng it is the
+    * responsibility of libpng because PNG carries the bomb and libpng is in a
+    * position to protect against it.
+    */
+   png_XYZ XYZ;
+
+   switch (png_colorspace_check_xy(&XYZ, xy))
+   {
+      case 0: /* success */
+         return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, xy, &XYZ,
+            preferred);
+
       case 1:
-         /* The chunk may be technically valid, but we got png_fixed_point
-          * overflow while trying to get XYZ values out of it.  This is
-          * entirely benign - the cHRM chunk is pretty extreme.
+         /* We can't invert the chromaticities so we can't produce value XYZ
+          * values.  Likely as not a color management system will fail too.
           */
-         png_warning(png_ptr,
-            "extreme cHRM chunk cannot be converted to tristimulus values");
+         colorspace->flags |= PNG_COLORSPACE_INVALID;
+         png_benign_error(png_ptr, "invalid chromaticities");
          break;
 
       default:
          /* libpng is broken; this should be a warning but if it happens we
           * want error reports so for the moment it is an error.
           */
-         png_error(png_ptr, "internal error in png_XYZ_from_xy");
+         colorspace->flags |= PNG_COLORSPACE_INVALID;
+         png_error(png_ptr, "internal error checking chromaticities");
+         break;
+   }
+
+   return 0; /* failed */
+}
+
+int /* PRIVATE */
+png_colorspace_set_endpoints(png_const_structrp png_ptr,
+   png_colorspacerp colorspace, const png_XYZ *XYZ_in, int preferred)
+{
+   png_XYZ XYZ = *XYZ_in;
+   png_xy xy;
+
+   switch (png_colorspace_check_XYZ(&xy, &XYZ))
+   {
+      case 0:
+         return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, &xy, &XYZ,
+            preferred);
+
+      case 1:
+         /* End points are invalid. */
+         colorspace->flags |= PNG_COLORSPACE_INVALID;
+         png_benign_error(png_ptr, "invalid end points");
+         break;
+
+      default:
+         colorspace->flags |= PNG_COLORSPACE_INVALID;
+         png_error(png_ptr, "internal error checking chromaticities");
          break;
    }
 
-   /* ERROR RETURN */
+   return 0; /* failed */
+}
+
+#if defined(PNG_sRGB_SUPPORTED) || defined(PNG_iCCP_SUPPORTED)
+/* Error message generation */
+static char
+png_icc_tag_char(png_uint_32 byte)
+{
+   byte &= 0xff;
+   if (byte >= 32 && byte <= 126)
+      return (char)byte;
+   else
+      return '?';
+}
+
+static void
+png_icc_tag_name(char *name, png_uint_32 tag)
+{
+   name[0] = '\'';
+   name[1] = png_icc_tag_char(tag >> 24);
+   name[2] = png_icc_tag_char(tag >> 16);
+   name[3] = png_icc_tag_char(tag >>  8);
+   name[4] = png_icc_tag_char(tag      );
+   name[5] = '\'';
+}
+
+static int
+is_ICC_signature_char(png_alloc_size_t it)
+{
+   return it == 32 || (it >= 48 && it <= 57) || (it >= 65 && it <= 90) ||
+      (it >= 97 && it <= 122);
+}
+
+static int
+is_ICC_signature(png_alloc_size_t it)
+{
+   return is_ICC_signature_char(it >> 24) /* checks all the top bits */ &&
+      is_ICC_signature_char((it >> 16) & 0xff) &&
+      is_ICC_signature_char((it >> 8) & 0xff) &&
+      is_ICC_signature_char(it & 0xff);
+}
+
+static int
+png_icc_profile_error(png_const_structrp png_ptr, png_colorspacerp colorspace,
+   png_const_charp name, png_alloc_size_t value, png_const_charp reason)
+{
+   size_t pos;
+   char message[196]; /* see below for calculation */
+
+   if (colorspace != NULL)
+      colorspace->flags |= PNG_COLORSPACE_INVALID;
+
+   pos = png_safecat(message, (sizeof message), 0, "profile '"); /* 9 chars */
+   pos = png_safecat(message, pos+79, pos, name); /* Truncate to 79 chars */
+   pos = png_safecat(message, (sizeof message), pos, "': "); /* +2 = 90 */
+   if (is_ICC_signature(value) != 0)
+   {
+      /* So 'value' is at most 4 bytes and the following cast is safe */
+      png_icc_tag_name(message+pos, (png_uint_32)value);
+      pos += 6; /* total +8; less than the else clause */
+      message[pos++] = ':';
+      message[pos++] = ' ';
+   }
+#  ifdef PNG_WARNINGS_SUPPORTED
+   else
+      {
+         char number[PNG_NUMBER_BUFFER_SIZE]; /* +24 = 114*/
+
+         pos = png_safecat(message, (sizeof message), pos,
+            png_format_number(number, number+(sizeof number),
+               PNG_NUMBER_FORMAT_x, value));
+         pos = png_safecat(message, (sizeof message), pos, "h: "); /*+2 = 116*/
+      }
+#  endif
+   /* The 'reason' is an arbitrary message, allow +79 maximum 195 */
+   pos = png_safecat(message, (sizeof message), pos, reason);
+   PNG_UNUSED(pos)
+
+   /* This is recoverable, but make it unconditionally an app_error on write to
+    * avoid writing invalid ICC profiles into PNG files (i.e., we handle them
+    * on read, with a warning, but on write unless the app turns off
+    * application errors the PNG won't be written.)
+    */
+   png_chunk_report(png_ptr, message,
+      (colorspace != NULL) ? PNG_CHUNK_ERROR : PNG_CHUNK_WRITE_ERROR);
+
    return 0;
 }
+#endif /* sRGB || iCCP */
+
+#ifdef PNG_sRGB_SUPPORTED
+int /* PRIVATE */
+png_colorspace_set_sRGB(png_const_structrp png_ptr, png_colorspacerp colorspace,
+   int intent)
+{
+   /* sRGB sets known gamma, end points and (from the chunk) intent. */
+   /* IMPORTANT: these are not necessarily the values found in an ICC profile
+    * because ICC profiles store values adapted to a D50 environment; it is
+    * expected that the ICC profile mediaWhitePointTag will be D50; see the
+    * checks and code elsewhere to understand this better.
+    *
+    * These XYZ values, which are accurate to 5dp, produce rgb to gray
+    * coefficients of (6968,23435,2366), which are reduced (because they add up
+    * to 32769 not 32768) to (6968,23434,2366).  These are the values that
+    * libpng has traditionally used (and are the best values given the 15bit
+    * algorithm used by the rgb to gray code.)
+    */
+   static const png_XYZ sRGB_XYZ = /* D65 XYZ (*not* the D50 adapted values!) */
+   {
+      /* color      X      Y      Z */
+      /* red   */ 41239, 21264,  1933,
+      /* green */ 35758, 71517, 11919,
+      /* blue  */ 18048,  7219, 95053
+   };
+
+   /* Do nothing if the colorspace is already invalidated. */
+   if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
+      return 0;
+
+   /* Check the intent, then check for existing settings.  It is valid for the
+    * PNG file to have cHRM or gAMA chunks along with sRGB, but the values must
+    * be consistent with the correct values.  If, however, this function is
+    * called below because an iCCP chunk matches sRGB then it is quite
+    * conceivable that an older app recorded incorrect gAMA and cHRM because of
+    * an incorrect calculation based on the values in the profile - this does
+    * *not* invalidate the profile (though it still produces an error, which can
+    * be ignored.)
+    */
+   if (intent < 0 || intent >= PNG_sRGB_INTENT_LAST)
+      return png_icc_profile_error(png_ptr, colorspace, "sRGB",
+         (unsigned)intent, "invalid sRGB rendering intent");
+
+   if ((colorspace->flags & PNG_COLORSPACE_HAVE_INTENT) != 0 &&
+      colorspace->rendering_intent != intent)
+      return png_icc_profile_error(png_ptr, colorspace, "sRGB",
+         (unsigned)intent, "inconsistent rendering intents");
+
+   if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0)
+   {
+      png_benign_error(png_ptr, "duplicate sRGB information ignored");
+      return 0;
+   }
+
+   /* If the standard sRGB cHRM chunk does not match the one from the PNG file
+    * warn but overwrite the value with the correct one.
+    */
+   if ((colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0 &&
+      !png_colorspace_endpoints_match(&sRGB_xy, &colorspace->end_points_xy,
+         100))
+      png_chunk_report(png_ptr, "cHRM chunk does not match sRGB",
+         PNG_CHUNK_ERROR);
+
+   /* This check is just done for the error reporting - the routine always
+    * returns true when the 'from' argument corresponds to sRGB (2).
+    */
+   (void)png_colorspace_check_gamma(png_ptr, colorspace, PNG_GAMMA_sRGB_INVERSE,
+      2/*from sRGB*/);
+
+   /* intent: bugs in GCC force 'int' to be used as the parameter type. */
+   colorspace->rendering_intent = (png_uint_16)intent;
+   colorspace->flags |= PNG_COLORSPACE_HAVE_INTENT;
+
+   /* endpoints */
+   colorspace->end_points_xy = sRGB_xy;
+   colorspace->end_points_XYZ = sRGB_XYZ;
+   colorspace->flags |=
+      (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB);
+
+   /* gamma */
+   colorspace->gamma = PNG_GAMMA_sRGB_INVERSE;
+   colorspace->flags |= PNG_COLORSPACE_HAVE_GAMMA;
+
+   /* Finally record that we have an sRGB profile */
+   colorspace->flags |=
+      (PNG_COLORSPACE_MATCHES_sRGB|PNG_COLORSPACE_FROM_sRGB);
+
+   return 1; /* set */
+}
+#endif /* sRGB */
+
+#ifdef PNG_iCCP_SUPPORTED
+/* Encoded value of D50 as an ICC XYZNumber.  From the ICC 2010 spec the value
+ * is XYZ(0.9642,1.0,0.8249), which scales to:
+ *
+ *    (63189.8112, 65536, 54060.6464)
+ */
+static const png_byte D50_nCIEXYZ[12] =
+   { 0x00, 0x00, 0xf6, 0xd6, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0xd3, 0x2d };
+
+int /* PRIVATE */
+png_icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace,
+   png_const_charp name, png_uint_32 profile_length)
+{
+   if (profile_length < 132)
+      return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
+         "too short");
+
+   return 1;
+}
+
+int /* PRIVATE */
+png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
+   png_const_charp name, png_uint_32 profile_length,
+   png_const_bytep profile/* first 132 bytes only */, int color_type)
+{
+   png_uint_32 temp;
+
+   /* Length check; this cannot be ignored in this code because profile_length
+    * is used later to check the tag table, so even if the profile seems over
+    * long profile_length from the caller must be correct.  The caller can fix
+    * this up on read or write by just passing in the profile header length.
+    */
+   temp = png_get_uint_32(profile);
+   if (temp != profile_length)
+      return png_icc_profile_error(png_ptr, colorspace, name, temp,
+         "length does not match profile");
+
+   temp = (png_uint_32) (*(profile+8));
+   if (temp > 3 && (profile_length & 3))
+      return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
+         "invalid length");
+
+   temp = png_get_uint_32(profile+128); /* tag count: 12 bytes/tag */
+   if (temp > 357913930 || /* (2^32-4-132)/12: maximum possible tag count */
+      profile_length < 132+12*temp) /* truncated tag table */
+      return png_icc_profile_error(png_ptr, colorspace, name, temp,
+         "tag count too large");
+
+   /* The 'intent' must be valid or we can't store it, ICC limits the intent to
+    * 16 bits.
+    */
+   temp = png_get_uint_32(profile+64);
+   if (temp >= 0xffff) /* The ICC limit */
+      return png_icc_profile_error(png_ptr, colorspace, name, temp,
+         "invalid rendering intent");
+
+   /* This is just a warning because the profile may be valid in future
+    * versions.
+    */
+   if (temp >= PNG_sRGB_INTENT_LAST)
+      (void)png_icc_profile_error(png_ptr, NULL, name, temp,
+         "intent outside defined range");
+
+   /* At this point the tag table can't be checked because it hasn't necessarily
+    * been loaded; however, various header fields can be checked.  These checks
+    * are for values permitted by the PNG spec in an ICC profile; the PNG spec
+    * restricts the profiles that can be passed in an iCCP chunk (they must be
+    * appropriate to processing PNG data!)
+    */
+
+   /* Data checks (could be skipped).  These checks must be independent of the
+    * version number; however, the version number doesn't accomodate changes in
+    * the header fields (just the known tags and the interpretation of the
+    * data.)
+    */
+   temp = png_get_uint_32(profile+36); /* signature 'ascp' */
+   if (temp != 0x61637370)
+      return png_icc_profile_error(png_ptr, colorspace, name, temp,
+         "invalid signature");
+
+   /* Currently the PCS illuminant/adopted white point (the computational
+    * white point) are required to be D50,
+    * however the profile contains a record of the illuminant so perhaps ICC
+    * expects to be able to change this in the future (despite the rationale in
+    * the introduction for using a fixed PCS adopted white.)  Consequently the
+    * following is just a warning.
+    */
+   if (memcmp(profile+68, D50_nCIEXYZ, 12) != 0)
+      (void)png_icc_profile_error(png_ptr, NULL, name, 0/*no tag value*/,
+         "PCS illuminant is not D50");
+
+   /* The PNG spec requires this:
+    * "If the iCCP chunk is present, the image samples conform to the colour
+    * space represented by the embedded ICC profile as defined by the
+    * International Color Consortium [ICC]. The colour space of the ICC profile
+    * shall be an RGB colour space for colour images (PNG colour types 2, 3, and
+    * 6), or a greyscale colour space for greyscale images (PNG colour types 0
+    * and 4)."
+    *
+    * This checking code ensures the embedded profile (on either read or write)
+    * conforms to the specification requirements.  Notice that an ICC 'gray'
+    * color-space profile contains the information to transform the monochrome
+    * data to XYZ or L*a*b (according to which PCS the profile uses) and this
+    * should be used in preference to the standard libpng K channel replication
+    * into R, G and B channels.
+    *
+    * Previously it was suggested that an RGB profile on grayscale data could be
+    * handled.  However it it is clear that using an RGB profile in this context
+    * must be an error - there is no specification of what it means.  Thus it is
+    * almost certainly more correct to ignore the profile.
+    */
+   temp = png_get_uint_32(profile+16); /* data colour space field */
+   switch (temp)
+   {
+      case 0x52474220: /* 'RGB ' */
+         if ((color_type & PNG_COLOR_MASK_COLOR) == 0)
+            return png_icc_profile_error(png_ptr, colorspace, name, temp,
+               "RGB color space not permitted on grayscale PNG");
+         break;
+
+      case 0x47524159: /* 'GRAY' */
+         if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
+            return png_icc_profile_error(png_ptr, colorspace, name, temp,
+               "Gray color space not permitted on RGB PNG");
+         break;
+
+      default:
+         return png_icc_profile_error(png_ptr, colorspace, name, temp,
+            "invalid ICC profile color space");
+   }
+
+   /* It is up to the application to check that the profile class matches the
+    * application requirements; the spec provides no guidance, but it's pretty
+    * weird if the profile is not scanner ('scnr'), monitor ('mntr'), printer
+    * ('prtr') or 'spac' (for generic color spaces).  Issue a warning in these
+    * cases.  Issue an error for device link or abstract profiles - these don't
+    * contain the records necessary to transform the color-space to anything
+    * other than the target device (and not even that for an abstract profile).
+    * Profiles of these classes may not be embedded in images.
+    */
+   temp = png_get_uint_32(profile+12); /* profile/device class */
+   switch (temp)
+   {
+      case 0x73636E72: /* 'scnr' */
+      case 0x6D6E7472: /* 'mntr' */
+      case 0x70727472: /* 'prtr' */
+      case 0x73706163: /* 'spac' */
+         /* All supported */
+         break;
+
+      case 0x61627374: /* 'abst' */
+         /* May not be embedded in an image */
+         return png_icc_profile_error(png_ptr, colorspace, name, temp,
+            "invalid embedded Abstract ICC profile");
+
+      case 0x6C696E6B: /* 'link' */
+         /* DeviceLink profiles cannot be interpreted in a non-device specific
+          * fashion, if an app uses the AToB0Tag in the profile the results are
+          * undefined unless the result is sent to the intended device,
+          * therefore a DeviceLink profile should not be found embedded in a
+          * PNG.
+          */
+         return png_icc_profile_error(png_ptr, colorspace, name, temp,
+            "unexpected DeviceLink ICC profile class");
+
+      case 0x6E6D636C: /* 'nmcl' */
+         /* A NamedColor profile is also device specific, however it doesn't
+          * contain an AToB0 tag that is open to misinterpretation.  Almost
+          * certainly it will fail the tests below.
+          */
+         (void)png_icc_profile_error(png_ptr, NULL, name, temp,
+            "unexpected NamedColor ICC profile class");
+         break;
+
+      default:
+         /* To allow for future enhancements to the profile accept unrecognized
+          * profile classes with a warning, these then hit the test below on the
+          * tag content to ensure they are backward compatible with one of the
+          * understood profiles.
+          */
+         (void)png_icc_profile_error(png_ptr, NULL, name, temp,
+            "unrecognized ICC profile class");
+         break;
+   }
+
+   /* For any profile other than a device link one the PCS must be encoded
+    * either in XYZ or Lab.
+    */
+   temp = png_get_uint_32(profile+20);
+   switch (temp)
+   {
+      case 0x58595A20: /* 'XYZ ' */
+      case 0x4C616220: /* 'Lab ' */
+         break;
+
+      default:
+         return png_icc_profile_error(png_ptr, colorspace, name, temp,
+            "unexpected ICC PCS encoding");
+   }
+
+   return 1;
+}
+
+int /* PRIVATE */
+png_icc_check_tag_table(png_const_structrp png_ptr, png_colorspacerp colorspace,
+   png_const_charp name, png_uint_32 profile_length,
+   png_const_bytep profile /* header plus whole tag table */)
+{
+   png_uint_32 tag_count = png_get_uint_32(profile+128);
+   png_uint_32 itag;
+   png_const_bytep tag = profile+132; /* The first tag */
+
+   /* First scan all the tags in the table and add bits to the icc_info value
+    * (temporarily in 'tags').
+    */
+   for (itag=0; itag < tag_count; ++itag, tag += 12)
+   {
+      png_uint_32 tag_id = png_get_uint_32(tag+0);
+      png_uint_32 tag_start = png_get_uint_32(tag+4); /* must be aligned */
+      png_uint_32 tag_length = png_get_uint_32(tag+8);/* not padded */
+
+      /* The ICC specification does not exclude zero length tags, therefore the
+       * start might actually be anywhere if there is no data, but this would be
+       * a clear abuse of the intent of the standard so the start is checked for
+       * being in range.  All defined tag types have an 8 byte header - a 4 byte
+       * type signature then 0.
+       */
+      if ((tag_start & 3) != 0)
+      {
+         /* CNHP730S.icc shipped with Microsoft Windows 64 violates this, it is
+          * only a warning here because libpng does not care about the
+          * alignment.
+          */
+         (void)png_icc_profile_error(png_ptr, NULL, name, tag_id,
+            "ICC profile tag start not a multiple of 4");
+      }
+
+      /* This is a hard error; potentially it can cause read outside the
+       * profile.
+       */
+      if (tag_start > profile_length || tag_length > profile_length - tag_start)
+         return png_icc_profile_error(png_ptr, colorspace, name, tag_id,
+            "ICC profile tag outside profile");
+   }
+
+   return 1; /* success, maybe with warnings */
+}
+
+#ifdef PNG_sRGB_SUPPORTED
+#if PNG_sRGB_PROFILE_CHECKS >= 0
+/* Information about the known ICC sRGB profiles */
+static const struct
+{
+   png_uint_32 adler, crc, length;
+   png_uint_32 md5[4];
+   png_byte    have_md5;
+   png_byte    is_broken;
+   png_uint_16 intent;
+
+#  define PNG_MD5(a,b,c,d) { a, b, c, d }, (a!=0)||(b!=0)||(c!=0)||(d!=0)
+#  define PNG_ICC_CHECKSUM(adler, crc, md5, intent, broke, date, length, fname)\
+      { adler, crc, length, md5, broke, intent },
+
+} png_sRGB_checks[] =
+{
+   /* This data comes from contrib/tools/checksum-icc run on downloads of
+    * all four ICC sRGB profiles from www.color.org.
+    */
+   /* adler32, crc32, MD5[4], intent, date, length, file-name */
+   PNG_ICC_CHECKSUM(0x0a3fd9f6, 0x3b8772b9,
+      PNG_MD5(0x29f83dde, 0xaff255ae, 0x7842fae4, 0xca83390d), 0, 0,
+      "2009/03/27 21:36:31", 3048, "sRGB_IEC61966-2-1_black_scaled.icc")
+
+   /* ICC sRGB v2 perceptual no black-compensation: */
+   PNG_ICC_CHECKSUM(0x4909e5e1, 0x427ebb21,
+      PNG_MD5(0xc95bd637, 0xe95d8a3b, 0x0df38f99, 0xc1320389), 1, 0,
+      "2009/03/27 21:37:45", 3052, "sRGB_IEC61966-2-1_no_black_scaling.icc")
+
+   PNG_ICC_CHECKSUM(0xfd2144a1, 0x306fd8ae,
+      PNG_MD5(0xfc663378, 0x37e2886b, 0xfd72e983, 0x8228f1b8), 0, 0,
+      "2009/08/10 17:28:01", 60988, "sRGB_v4_ICC_preference_displayclass.icc")
+
+   /* ICC sRGB v4 perceptual */
+   PNG_ICC_CHECKSUM(0x209c35d2, 0xbbef7812,
+      PNG_MD5(0x34562abf, 0x994ccd06, 0x6d2c5721, 0xd0d68c5d), 0, 0,
+      "2007/07/25 00:05:37", 60960, "sRGB_v4_ICC_preference.icc")
+
+   /* The following profiles have no known MD5 checksum. If there is a match
+    * on the (empty) MD5 the other fields are used to attempt a match and
+    * a warning is produced.  The first two of these profiles have a 'cprt' tag
+    * which suggests that they were also made by Hewlett Packard.
+    */
+   PNG_ICC_CHECKSUM(0xa054d762, 0x5d5129ce,
+      PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 0,
+      "2004/07/21 18:57:42", 3024, "sRGB_IEC61966-2-1_noBPC.icc")
+
+   /* This is a 'mntr' (display) profile with a mediaWhitePointTag that does not
+    * match the D50 PCS illuminant in the header (it is in fact the D65 values,
+    * so the white point is recorded as the un-adapted value.)  The profiles
+    * below only differ in one byte - the intent - and are basically the same as
+    * the previous profile except for the mediaWhitePointTag error and a missing
+    * chromaticAdaptationTag.
+    */
+   PNG_ICC_CHECKSUM(0xf784f3fb, 0x182ea552,
+      PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 0, 1/*broken*/,
+      "1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 perceptual")
+
+   PNG_ICC_CHECKSUM(0x0398f3fc, 0xf29e526d,
+      PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 1/*broken*/,
+      "1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 media-relative")
+};
+
+static int
+png_compare_ICC_profile_with_sRGB(png_const_structrp png_ptr,
+   png_const_bytep profile, uLong adler)
+{
+   /* The quick check is to verify just the MD5 signature and trust the
+    * rest of the data.  Because the profile has already been verified for
+    * correctness this is safe.  png_colorspace_set_sRGB will check the 'intent'
+    * field too, so if the profile has been edited with an intent not defined
+    * by sRGB (but maybe defined by a later ICC specification) the read of
+    * the profile will fail at that point.
+    */
+
+   png_uint_32 length = 0;
+   png_uint_32 intent = 0x10000; /* invalid */
+#if PNG_sRGB_PROFILE_CHECKS > 1
+   uLong crc = 0; /* the value for 0 length data */
+#endif
+   unsigned int i;
+
+#ifdef PNG_SET_OPTION_SUPPORTED
+   /* First see if PNG_SKIP_sRGB_CHECK_PROFILE has been set to "on" */
+   if (((png_ptr->options >> PNG_SKIP_sRGB_CHECK_PROFILE) & 3) ==
+               PNG_OPTION_ON)
+      return 0;
+#endif
+
+   for (i=0; i < (sizeof png_sRGB_checks) / (sizeof png_sRGB_checks[0]); ++i)
+   {
+      if (png_get_uint_32(profile+84) == png_sRGB_checks[i].md5[0] &&
+         png_get_uint_32(profile+88) == png_sRGB_checks[i].md5[1] &&
+         png_get_uint_32(profile+92) == png_sRGB_checks[i].md5[2] &&
+         png_get_uint_32(profile+96) == png_sRGB_checks[i].md5[3])
+      {
+         /* This may be one of the old HP profiles without an MD5, in that
+          * case we can only use the length and Adler32 (note that these
+          * are not used by default if there is an MD5!)
+          */
+#        if PNG_sRGB_PROFILE_CHECKS == 0
+            if (png_sRGB_checks[i].have_md5 != 0)
+               return 1+png_sRGB_checks[i].is_broken;
+#        endif
+
+         /* Profile is unsigned or more checks have been configured in. */
+         if (length == 0)
+         {
+            length = png_get_uint_32(profile);
+            intent = png_get_uint_32(profile+64);
+         }
+
+         /* Length *and* intent must match */
+         if (length == png_sRGB_checks[i].length &&
+            intent == png_sRGB_checks[i].intent)
+         {
+            /* Now calculate the adler32 if not done already. */
+            if (adler == 0)
+            {
+               adler = adler32(0, NULL, 0);
+               adler = adler32(adler, profile, length);
+            }
+
+            if (adler == png_sRGB_checks[i].adler)
+            {
+               /* These basic checks suggest that the data has not been
+                * modified, but if the check level is more than 1 perform
+                * our own crc32 checksum on the data.
+                */
+#              if PNG_sRGB_PROFILE_CHECKS > 1
+                  if (crc == 0)
+                  {
+                     crc = crc32(0, NULL, 0);
+                     crc = crc32(crc, profile, length);
+                  }
+
+                  /* So this check must pass for the 'return' below to happen.
+                   */
+                  if (crc == png_sRGB_checks[i].crc)
+#              endif
+               {
+                  if (png_sRGB_checks[i].is_broken != 0)
+                  {
+                     /* These profiles are known to have bad data that may cause
+                      * problems if they are used, therefore attempt to
+                      * discourage their use, skip the 'have_md5' warning below,
+                      * which is made irrelevant by this error.
+                      */
+                     png_chunk_report(png_ptr, "known incorrect sRGB profile",
+                        PNG_CHUNK_ERROR);
+                  }
+
+                  /* Warn that this being done; this isn't even an error since
+                   * the profile is perfectly valid, but it would be nice if
+                   * people used the up-to-date ones.
+                   */
+                  else if (png_sRGB_checks[i].have_md5 == 0)
+                  {
+                     png_chunk_report(png_ptr,
+                        "out-of-date sRGB profile with no signature",
+                        PNG_CHUNK_WARNING);
+                  }
+
+                  return 1+png_sRGB_checks[i].is_broken;
+               }
+            }
+
+# if PNG_sRGB_PROFILE_CHECKS > 0
+         /* The signature matched, but the profile had been changed in some
+          * way.  This probably indicates a data error or uninformed hacking.
+          * Fall through to "no match".
+          */
+         png_chunk_report(png_ptr,
+             "Not recognizing known sRGB profile that has been edited", 
+             PNG_CHUNK_WARNING);
+         break;
+# endif
+         }
+      }
+   }
+
+   return 0; /* no match */
+}
+#endif /* PNG_sRGB_PROFILE_CHECKS >= 0 */
+
+void /* PRIVATE */
+png_icc_set_sRGB(png_const_structrp png_ptr,
+   png_colorspacerp colorspace, png_const_bytep profile, uLong adler)
+{
+   /* Is this profile one of the known ICC sRGB profiles?  If it is, just set
+    * the sRGB information.
+    */
+#if PNG_sRGB_PROFILE_CHECKS >= 0
+   if (png_compare_ICC_profile_with_sRGB(png_ptr, profile, adler) != 0)
+#endif
+      (void)png_colorspace_set_sRGB(png_ptr, colorspace,
+         (int)/*already checked*/png_get_uint_32(profile+64));
+}
+#endif /* sRGB */
+
+int /* PRIVATE */
+png_colorspace_set_ICC(png_const_structrp png_ptr, png_colorspacerp colorspace,
+   png_const_charp name, png_uint_32 profile_length, png_const_bytep profile,
+   int color_type)
+{
+   if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
+      return 0;
+
+   if (png_icc_check_length(png_ptr, colorspace, name, profile_length) != 0 &&
+       png_icc_check_header(png_ptr, colorspace, name, profile_length, profile,
+          color_type) != 0 &&
+       png_icc_check_tag_table(png_ptr, colorspace, name, profile_length,
+          profile) != 0)
+   {
+#     ifdef PNG_sRGB_SUPPORTED
+         /* If no sRGB support, don't try storing sRGB information */
+         png_icc_set_sRGB(png_ptr, colorspace, profile, 0);
+#     endif
+      return 1;
+   }
+
+   /* Failure case */
+   return 0;
+}
+#endif /* iCCP */
+
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+void /* PRIVATE */
+png_colorspace_set_rgb_coefficients(png_structrp png_ptr)
+{
+   /* Set the rgb_to_gray coefficients from the colorspace. */
+   if (png_ptr->rgb_to_gray_coefficients_set == 0 &&
+      (png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
+   {
+      /* png_set_background has not been called, get the coefficients from the Y
+       * values of the colorspace colorants.
+       */
+      png_fixed_point r = png_ptr->colorspace.end_points_XYZ.red_Y;
+      png_fixed_point g = png_ptr->colorspace.end_points_XYZ.green_Y;
+      png_fixed_point b = png_ptr->colorspace.end_points_XYZ.blue_Y;
+      png_fixed_point total = r+g+b;
+
+      if (total > 0 &&
+         r >= 0 && png_muldiv(&r, r, 32768, total) && r >= 0 && r <= 32768 &&
+         g >= 0 && png_muldiv(&g, g, 32768, total) && g >= 0 && g <= 32768 &&
+         b >= 0 && png_muldiv(&b, b, 32768, total) && b >= 0 && b <= 32768 &&
+         r+g+b <= 32769)
+      {
+         /* We allow 0 coefficients here.  r+g+b may be 32769 if two or
+          * all of the coefficients were rounded up.  Handle this by
+          * reducing the *largest* coefficient by 1; this matches the
+          * approach used for the default coefficients in pngrtran.c
+          */
+         int add = 0;
+
+         if (r+g+b > 32768)
+            add = -1;
+         else if (r+g+b < 32768)
+            add = 1;
+
+         if (add != 0)
+         {
+            if (g >= r && g >= b)
+               g += add;
+            else if (r >= g && r >= b)
+               r += add;
+            else
+               b += add;
+         }
+
+         /* Check for an internal error. */
+         if (r+g+b != 32768)
+            png_error(png_ptr,
+               "internal error handling cHRM coefficients");
+
+         else
+         {
+            png_ptr->rgb_to_gray_red_coeff   = (png_uint_16)r;
+            png_ptr->rgb_to_gray_green_coeff = (png_uint_16)g;
+         }
+      }
+
+      /* This is a png_error at present even though it could be ignored -
+       * it should never happen, but it is important that if it does, the
+       * bug is fixed.
+       */
+      else
+         png_error(png_ptr, "internal error handling cHRM->XYZ");
+   }
+}
+#endif /* READ_RGB_TO_GRAY */
+
+#endif /* COLORSPACE */
+
+#ifdef __GNUC__
+/* This exists solely to work round a warning from GNU C. */
+static int /* PRIVATE */
+png_gt(size_t a, size_t b)
+{
+    return a > b;
+}
+#else
+#   define png_gt(a,b) ((a) > (b))
 #endif
 
 void /* PRIVATE */
-png_check_IHDR(png_structp png_ptr,
+png_check_IHDR(png_const_structrp png_ptr,
    png_uint_32 width, png_uint_32 height, int bit_depth,
    int color_type, int interlace_type, int compression_type,
    int filter_type)
@@ -1180,36 +2482,47 @@ png_check_IHDR(png_structp png_ptr,
       error = 1;
    }
 
-   if (height == 0)
+   if (width > PNG_UINT_31_MAX)
    {
-      png_warning(png_ptr, "Image height is zero in IHDR");
+      png_warning(png_ptr, "Invalid image width in IHDR");
       error = 1;
    }
 
-#  ifdef PNG_SET_USER_LIMITS_SUPPORTED
-   if (width > png_ptr->user_width_max)
-
-#  else
-   if (width > PNG_USER_WIDTH_MAX)
-#  endif
+   if (png_gt(((width + 7) & (~7)),
+       ((PNG_SIZE_MAX
+           - 48        /* big_row_buf hack */
+           - 1)        /* filter byte */
+           / 8)        /* 8-byte RGBA pixels */
+           - 1))       /* extra max_pixel_depth pad */
    {
-      png_warning(png_ptr, "Image width exceeds user limit in IHDR");
+      /* The size of the row must be within the limits of this architecture.
+       * Because the read code can perform arbitrary transformations the
+       * maximum size is checked here.  Because the code in png_read_start_row
+       * adds extra space "for safety's sake" in several places a conservative
+       * limit is used here.
+       *
+       * NOTE: it would be far better to check the size that is actually used,
+       * but the effect in the real world is minor and the changes are more
+       * extensive, therefore much more dangerous and much more difficult to
+       * write in a way that avoids compiler warnings.
+       */
+      png_warning(png_ptr, "Image width is too large for this architecture");
       error = 1;
    }
 
-#  ifdef PNG_SET_USER_LIMITS_SUPPORTED
-   if (height > png_ptr->user_height_max)
-#  else
-   if (height > PNG_USER_HEIGHT_MAX)
-#  endif
+#ifdef PNG_SET_USER_LIMITS_SUPPORTED
+   if (width > png_ptr->user_width_max)
+#else
+   if (width > PNG_USER_WIDTH_MAX)
+#endif
    {
-      png_warning(png_ptr, "Image height exceeds user limit in IHDR");
+      png_warning(png_ptr, "Image width exceeds user limit in IHDR");
       error = 1;
    }
 
-   if (width > PNG_UINT_31_MAX)
+   if (height == 0)
    {
-      png_warning(png_ptr, "Invalid image width in IHDR");
+      png_warning(png_ptr, "Image height is zero in IHDR");
       error = 1;
    }
 
@@ -1219,13 +2532,15 @@ png_check_IHDR(png_structp png_ptr,
       error = 1;
    }
 
-   if (width > (PNG_UINT_32_MAX
-                 >> 3)      /* 8-byte RGBA pixels */
-                 - 48       /* bigrowbuf hack */
-                 - 1        /* filter byte */
-                 - 7*8      /* rounding of width to multiple of 8 pixels */
-                 - 8)       /* extra max_pixel_depth pad */
-      png_warning(png_ptr, "Width is too large for libpng to process pixels");
+#ifdef PNG_SET_USER_LIMITS_SUPPORTED
+   if (height > png_ptr->user_height_max)
+#else
+   if (height > PNG_USER_HEIGHT_MAX)
+#endif
+   {
+      png_warning(png_ptr, "Image height exceeds user limit in IHDR");
+      error = 1;
+   }
 
    /* Check other values */
    if (bit_depth != 1 && bit_depth != 2 && bit_depth != 4 &&
@@ -1263,7 +2578,7 @@ png_check_IHDR(png_structp png_ptr,
       error = 1;
    }
 
-#  ifdef PNG_MNG_FEATURES_SUPPORTED
+#ifdef PNG_MNG_FEATURES_SUPPORTED
    /* Accept filter_method 64 (intrapixel differencing) only if
     * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
     * 2. Libpng did not read a PNG signature (this filter_method is only
@@ -1273,13 +2588,13 @@ png_check_IHDR(png_structp png_ptr,
     * 4. The filter_method is 64 and
     * 5. The color_type is RGB or RGBA
     */
-   if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) &&
-       png_ptr->mng_features_permitted)
+   if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0 &&
+       png_ptr->mng_features_permitted != 0)
       png_warning(png_ptr, "MNG features are not allowed in a PNG datastream");
 
    if (filter_type != PNG_FILTER_TYPE_BASE)
    {
-      if (!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
+      if (!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
           (filter_type == PNG_INTRAPIXEL_DIFFERENCING) &&
           ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) &&
           (color_type == PNG_COLOR_TYPE_RGB ||
@@ -1289,20 +2604,20 @@ png_check_IHDR(png_structp png_ptr,
          error = 1;
       }
 
-      if (png_ptr->mode & PNG_HAVE_PNG_SIGNATURE)
+      if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0)
       {
          png_warning(png_ptr, "Invalid filter method in IHDR");
          error = 1;
       }
    }
 
-#  else
+#else
    if (filter_type != PNG_FILTER_TYPE_BASE)
    {
       png_warning(png_ptr, "Unknown filter method in IHDR");
       error = 1;
    }
-#  endif
+#endif
 
    if (error == 1)
       png_error(png_ptr, "Invalid IHDR data");
@@ -1349,7 +2664,7 @@ png_check_fp_number(png_const_charp string, png_size_t size, int *statep,
       switch ((state & PNG_FP_STATE) + (type & PNG_FP_SAW_ANY))
       {
       case PNG_FP_INTEGER + PNG_FP_SAW_SIGN:
-         if (state & PNG_FP_SAW_ANY)
+         if ((state & PNG_FP_SAW_ANY) != 0)
             goto PNG_FP_End; /* not a part of the number */
 
          png_fp_add(state, type);
@@ -1357,10 +2672,10 @@ png_check_fp_number(png_const_charp string, png_size_t size, int *statep,
 
       case PNG_FP_INTEGER + PNG_FP_SAW_DOT:
          /* Ok as trailer, ok as lead of fraction. */
-         if (state & PNG_FP_SAW_DOT) /* two dots */
+         if ((state & PNG_FP_SAW_DOT) != 0) /* two dots */
             goto PNG_FP_End;
 
-         else if (state & PNG_FP_SAW_DIGIT) /* trailing dot? */
+         else if ((state & PNG_FP_SAW_DIGIT) != 0) /* trailing dot? */
             png_fp_add(state, type);
 
          else
@@ -1369,7 +2684,7 @@ png_check_fp_number(png_const_charp string, png_size_t size, int *statep,
          break;
 
       case PNG_FP_INTEGER + PNG_FP_SAW_DIGIT:
-         if (state & PNG_FP_SAW_DOT) /* delayed fraction */
+         if ((state & PNG_FP_SAW_DOT) != 0) /* delayed fraction */
             png_fp_set(state, PNG_FP_FRACTION | PNG_FP_SAW_DOT);
 
          png_fp_add(state, type | PNG_FP_WAS_VALID);
@@ -1407,7 +2722,7 @@ png_check_fp_number(png_const_charp string, png_size_t size, int *statep,
          break;
 
       case PNG_FP_EXPONENT + PNG_FP_SAW_SIGN:
-         if (state & PNG_FP_SAW_ANY)
+         if ((state & PNG_FP_SAW_ANY) != 0)
             goto PNG_FP_End; /* not a part of the number */
 
          png_fp_add(state, PNG_FP_SAW_SIGN);
@@ -1450,15 +2765,15 @@ png_check_fp_string(png_const_charp string, png_size_t size)
    int        state=0;
    png_size_t char_index=0;
 
-   if (png_check_fp_number(string, size, &state, &char_index) &&
+   if (png_check_fp_number(string, size, &state, &char_index) != 0 &&
       (char_index == size || string[char_index] == 0))
       return state /* must be non-zero - see above */;
 
    return 0; /* i.e. fail */
 }
-#endif /* pCAL or sCAL */
+#endif /* pCAL || sCAL */
 
-#ifdef PNG_READ_sCAL_SUPPORTED
+#ifdef PNG_sCAL_SUPPORTED
 #  ifdef PNG_FLOATING_POINT_SUPPORTED
 /* Utility used below - a simple accurate power of ten from an integral
  * exponent.
@@ -1467,7 +2782,7 @@ static double
 png_pow10(int power)
 {
    int recip = 0;
-   double d = 1.0;
+   double d = 1;
 
    /* Handle negative exponent with a reciprocal at the end because
     * 10 is exact whereas .1 is inexact in base 2
@@ -1481,7 +2796,7 @@ png_pow10(int power)
    if (power > 0)
    {
       /* Decompose power bitwise. */
-      double mult = 10.0;
+      double mult = 10;
       do
       {
          if (power & 1) d *= mult;
@@ -1490,7 +2805,7 @@ png_pow10(int power)
       }
       while (power > 0);
 
-      if (recip) d = 1/d;
+      if (recip != 0) d = 1/d;
    }
    /* else power is 0 and d is 1 */
 
@@ -1501,7 +2816,7 @@ png_pow10(int power)
  * precision.
  */
 void /* PRIVATE */
-png_ascii_from_fp(png_structp png_ptr, png_charp ascii, png_size_t size,
+png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,
     double fp, unsigned int precision)
 {
    /* We use standard functions from math.h, but not printf because
@@ -1600,8 +2915,7 @@ png_ascii_from_fp(png_structp png_ptr, png_charp ascii, png_size_t size,
             {
                double d;
 
-               fp *= 10.0;
-
+               fp *= 10;
                /* Use modf here, not floor and subtract, so that
                 * the separation is done in one step.  At the end
                 * of the loop don't break the number into parts so
@@ -1614,7 +2928,7 @@ png_ascii_from_fp(png_structp png_ptr, png_charp ascii, png_size_t size,
                {
                   d = floor(fp + .5);
 
-                  if (d > 9.0)
+                  if (d > 9)
                   {
                      /* Rounding up to 10, handle that here. */
                      if (czero > 0)
@@ -1622,10 +2936,9 @@ png_ascii_from_fp(png_structp png_ptr, png_charp ascii, png_size_t size,
                         --czero, d = 1;
                         if (cdigits == 0) --clead;
                      }
-
                      else
                      {
-                        while (cdigits > 0 && d > 9.0)
+                        while (cdigits > 0 && d > 9)
                         {
                            int ch = *--ascii;
 
@@ -1650,7 +2963,7 @@ png_ascii_from_fp(png_structp png_ptr, png_charp ascii, png_size_t size,
                          * exponent but take into account the leading
                          * decimal point.
                          */
-                        if (d > 9.0)  /* cdigits == 0 */
+                        if (d > 9)  /* cdigits == 0 */
                         {
                            if (exp_b10 == (-1))
                            {
@@ -1671,19 +2984,18 @@ png_ascii_from_fp(png_structp png_ptr, png_charp ascii, png_size_t size,
                               ++exp_b10;
 
                            /* In all cases we output a '1' */
-                           d = 1.0;
+                           d = 1;
                         }
                      }
                   }
                   fp = 0; /* Guarantees termination below. */
                }
 
-               if (d == 0.0)
+               if (d == 0)
                {
                   ++czero;
                   if (cdigits == 0) ++clead;
                }
-
                else
                {
                   /* Included embedded zeros in the digit count. */
@@ -1707,11 +3019,11 @@ png_ascii_from_fp(png_structp png_ptr, png_charp ascii, png_size_t size,
 
                   if (exp_b10 != (-1))
                   {
-                     if (exp_b10 == 0) *ascii++ = 46, --size; /* counted
-                                                                 above */
+                     if (exp_b10 == 0)
+                        *ascii++ = 46, --size; /* counted above */
+
                      --exp_b10;
                   }
-
                   *ascii++ = (char)(48 + (int)d), ++cdigits;
                }
             }
@@ -1722,7 +3034,7 @@ png_ascii_from_fp(png_structp png_ptr, png_charp ascii, png_size_t size,
             /* Check for an exponent, if we don't need one we are
              * done and just need to terminate the string.  At
              * this point exp_b10==(-1) is effectively if flag - it got
-             * to '-1' because of the decrement after outputing
+             * to '-1' because of the decrement after outputting
              * the decimal point above (the exponent required is
              * *not* -1!)
              */
@@ -1730,7 +3042,7 @@ png_ascii_from_fp(png_structp png_ptr, png_charp ascii, png_size_t size,
             {
                /* The following only happens if we didn't output the
                 * leading zeros above for negative exponent, so this
-                * doest add to the digit requirement.  Note that the
+                * doesn't add to the digit requirement.  Note that the
                 * two zeros here can only be output if the two leading
                 * zeros were *not* output, so this doesn't increase
                 * the output count.
@@ -1819,8 +3131,8 @@ png_ascii_from_fp(png_structp png_ptr, png_charp ascii, png_size_t size,
 /* Function to format a fixed point value in ASCII.
  */
 void /* PRIVATE */
-png_ascii_from_fixed(png_structp png_ptr, png_charp ascii, png_size_t size,
-    png_fixed_point fp)
+png_ascii_from_fixed(png_const_structrp png_ptr, png_charp ascii,
+    png_size_t size, png_fixed_point fp)
 {
    /* Require space for 10 decimal digits, a decimal point, a minus sign and a
     * trailing \0, 13 characters:
@@ -1887,24 +3199,33 @@ png_ascii_from_fixed(png_structp png_ptr, png_charp ascii, png_size_t size,
    png_error(png_ptr, "ASCII conversion buffer too small");
 }
 #   endif /* FIXED_POINT */
-#endif /* READ_SCAL */
+#endif /* SCAL */
 
 #if defined(PNG_FLOATING_POINT_SUPPORTED) && \
-   !defined(PNG_FIXED_POINT_MACRO_SUPPORTED)
+   !defined(PNG_FIXED_POINT_MACRO_SUPPORTED) && \
+   (defined(PNG_gAMA_SUPPORTED) || defined(PNG_cHRM_SUPPORTED) || \
+   defined(PNG_sCAL_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) || \
+   defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)) || \
+   (defined(PNG_sCAL_SUPPORTED) && \
+   defined(PNG_FLOATING_ARITHMETIC_SUPPORTED))
 png_fixed_point
-png_fixed(png_structp png_ptr, double fp, png_const_charp text)
+png_fixed(png_const_structrp png_ptr, double fp, png_const_charp text)
 {
    double r = floor(100000 * fp + .5);
 
    if (r > 2147483647. || r < -2147483648.)
       png_fixed_error(png_ptr, text);
 
+#  ifndef PNG_ERROR_TEXT_SUPPORTED
+   PNG_UNUSED(text)
+#  endif
+
    return (png_fixed_point)r;
 }
 #endif
 
-#if defined(PNG_READ_GAMMA_SUPPORTED) || \
-    defined(PNG_INCH_CONVERSIONS_SUPPORTED) || defined(PNG__READ_pHYs_SUPPORTED)
+#if defined(PNG_GAMMA_SUPPORTED) || defined(PNG_COLORSPACE_SUPPORTED) ||\
+    defined(PNG_INCH_CONVERSIONS_SUPPORTED) || defined(PNG_READ_pHYs_SUPPORTED)
 /* muldiv functions */
 /* This API takes signed arguments and rounds the result to the nearest
  * integer (or, for a fixed point number - the standard argument - to
@@ -2008,11 +3329,12 @@ png_muldiv(png_fixed_point_p res, png_fixed_point a, png_int_32 times,
             if (s00 >= (D >> 1))
                ++result;
 
-            if (negative)
+            if (negative != 0)
                result = -result;
 
             /* Check for overflow. */
-            if ((negative && result <= 0) || (!negative && result >= 0))
+            if ((negative != 0 && result <= 0) ||
+                (negative == 0 && result >= 0))
             {
                *res = result;
                return 1;
@@ -2031,12 +3353,12 @@ png_muldiv(png_fixed_point_p res, png_fixed_point a, png_int_32 times,
  * result.
  */
 png_fixed_point
-png_muldiv_warn(png_structp png_ptr, png_fixed_point a, png_int_32 times,
+png_muldiv_warn(png_const_structrp png_ptr, png_fixed_point a, png_int_32 times,
     png_int_32 divisor)
 {
    png_fixed_point result;
 
-   if (png_muldiv(&result, a, times, divisor))
+   if (png_muldiv(&result, a, times, divisor) != 0)
       return result;
 
    png_warning(png_ptr, "fixed point overflow ignored");
@@ -2044,7 +3366,7 @@ png_muldiv_warn(png_structp png_ptr, png_fixed_point a, png_int_32 times,
 }
 #endif
 
-#ifdef PNG_READ_GAMMA_SUPPORTED /* more fixed point functions for gammma */
+#ifdef PNG_GAMMA_SUPPORTED /* more fixed point functions for gamma */
 /* Calculate a reciprocal, return 0 on div-by-zero or overflow. */
 png_fixed_point
 png_reciprocal(png_fixed_point a)
@@ -2057,13 +3379,26 @@ png_reciprocal(png_fixed_point a)
 #else
    png_fixed_point res;
 
-   if (png_muldiv(&res, 100000, 100000, a))
+   if (png_muldiv(&res, 100000, 100000, a) != 0)
       return res;
 #endif
 
    return 0; /* error/overflow */
 }
 
+/* This is the shared test on whether a gamma value is 'significant' - whether
+ * it is worth doing gamma correction.
+ */
+int /* PRIVATE */
+png_gamma_significant(png_fixed_point gamma_val)
+{
+   return gamma_val < PNG_FP_1 - PNG_GAMMA_THRESHOLD_FIXED ||
+       gamma_val > PNG_FP_1 + PNG_GAMMA_THRESHOLD_FIXED;
+}
+#endif
+
+#ifdef PNG_READ_GAMMA_SUPPORTED
+#ifdef PNG_16BIT_SUPPORTED
 /* A local convenience routine. */
 static png_fixed_point
 png_product2(png_fixed_point a, png_fixed_point b)
@@ -2079,12 +3414,13 @@ png_product2(png_fixed_point a, png_fixed_point b)
 #else
    png_fixed_point res;
 
-   if (png_muldiv(&res, a, b, 100000))
+   if (png_muldiv(&res, a, b, 100000) != 0)
       return res;
 #endif
 
    return 0; /* overflow */
 }
+#endif /* 16BIT */
 
 /* The inverse of the above. */
 png_fixed_point
@@ -2092,12 +3428,15 @@ png_reciprocal2(png_fixed_point a, png_fixed_point b)
 {
    /* The required result is 1/a * 1/b; the following preserves accuracy. */
 #ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
-   double r = 1E15/a;
-   r /= b;
-   r = floor(r+.5);
+   if (a != 0 && b != 0)
+   {
+      double r = 1E15/a;
+      r /= b;
+      r = floor(r+.5);
 
-   if (r <= 2147483647. && r >= -2147483648.)
-      return (png_fixed_point)r;
+      if (r <= 2147483647. && r >= -2147483648.)
+         return (png_fixed_point)r;
+   }
 #else
    /* This may overflow because the range of png_fixed_point isn't symmetric,
     * but this API is only used for the product of file and screen gamma so it
@@ -2114,73 +3453,28 @@ png_reciprocal2(png_fixed_point a, png_fixed_point b)
 }
 #endif /* READ_GAMMA */
 
-#ifdef PNG_CHECK_cHRM_SUPPORTED
-/* Added at libpng version 1.2.34 (Dec 8, 2008) and 1.4.0 (Jan 2,
- * 2010: moved from pngset.c) */
-/*
- *    Multiply two 32-bit numbers, V1 and V2, using 32-bit
- *    arithmetic, to produce a 64-bit result in the HI/LO words.
- *
- *                  A B
- *                x C D
- *               ------
- *              AD || BD
- *        AC || CB || 0
- *
- *    where A and B are the high and low 16-bit words of V1,
- *    C and D are the 16-bit words of V2, AD is the product of
- *    A and D, and X || Y is (X << 16) + Y.
-*/
-
-void /* PRIVATE */
-png_64bit_product (long v1, long v2, unsigned long *hi_product,
-    unsigned long *lo_product)
-{
-   int a, b, c, d;
-   long lo, hi, x, y;
-
-   a = (v1 >> 16) & 0xffff;
-   b = v1 & 0xffff;
-   c = (v2 >> 16) & 0xffff;
-   d = v2 & 0xffff;
-
-   lo = b * d;                   /* BD */
-   x = a * d + c * b;            /* AD + CB */
-   y = ((lo >> 16) & 0xffff) + x;
-
-   lo = (lo & 0xffff) | ((y & 0xffff) << 16);
-   hi = (y >> 16) & 0xffff;
-
-   hi += a * c;                  /* AC */
-
-   *hi_product = (unsigned long)hi;
-   *lo_product = (unsigned long)lo;
-}
-#endif /* CHECK_cHRM */
-
 #ifdef PNG_READ_GAMMA_SUPPORTED /* gamma table code */
 #ifndef PNG_FLOATING_ARITHMETIC_SUPPORTED
 /* Fixed point gamma.
  *
+ * The code to calculate the tables used below can be found in the shell script
+ * contrib/tools/intgamma.sh
+ *
  * To calculate gamma this code implements fast log() and exp() calls using only
  * fixed point arithmetic.  This code has sufficient precision for either 8-bit
  * or 16-bit sample values.
  *
  * The tables used here were calculated using simple 'bc' programs, but C double
- * precision floating point arithmetic would work fine.  The programs are given
- * at the head of each table.
+ * precision floating point arithmetic would work fine.
  *
  * 8-bit log table
  *   This is a table of -log(value/255)/log(2) for 'value' in the range 128 to
  *   255, so it's the base 2 logarithm of a normalized 8-bit floating point
  *   mantissa.  The numbers are 32-bit fractions.
  */
-static png_uint_32
+static const png_uint_32
 png_8bit_l2[128] =
 {
-#  ifdef PNG_DO_BC
-      for (i=128;i<256;++i) { .5 - l(i/255)/l(2)*65536*65536; }
-#  else
    4270715492U, 4222494797U, 4174646467U, 4127164793U, 4080044201U, 4033279239U,
    3986864580U, 3940795015U, 3895065449U, 3849670902U, 3804606499U, 3759867474U,
    3715449162U, 3671346997U, 3627556511U, 3584073329U, 3540893168U, 3498011834U,
@@ -2203,7 +3497,6 @@ png_8bit_l2[128] =
    324227938U, 298676034U, 273229066U, 247886176U, 222646516U, 197509248U,
    172473545U, 147538590U, 122703574U, 97967701U, 73330182U, 48790236U,
    24347096U, 0U
-#  endif
 
 #if 0
    /* The following are the values for 16-bit tables - these work fine for the
@@ -2226,18 +3519,18 @@ png_8bit_l2[128] =
 #endif
 };
 
-PNG_STATIC png_int_32
+static png_int_32
 png_log8bit(unsigned int x)
 {
    unsigned int lg2 = 0;
    /* Each time 'x' is multiplied by 2, 1 must be subtracted off the final log,
     * because the log is actually negate that means adding 1.  The final
     * returned value thus has the range 0 (for 255 input) to 7.994 (for 1
-    * input), return 7.99998 for the overflow (log 0) case - so the result is
+    * input), return -1 for the overflow (log 0) case, - so the result is
     * always at most 19 bits.
     */
    if ((x &= 0xff) == 0)
-      return 0xffffffff;
+      return -1;
 
    if ((x & 0xf0) == 0)
       lg2  = 4, x <<= 4;
@@ -2282,14 +3575,15 @@ png_log8bit(unsigned int x)
  * Zero  (257):      0
  * End   (258):  23499
  */
-PNG_STATIC png_int_32
+#ifdef PNG_16BIT_SUPPORTED
+static png_int_32
 png_log16bit(png_uint_32 x)
 {
    unsigned int lg2 = 0;
 
    /* As above, but now the input has 16 bits. */
    if ((x &= 0xffff) == 0)
-      return 0xffffffff;
+      return -1;
 
    if ((x & 0xff00) == 0)
       lg2  = 8, x <<= 8;
@@ -2332,13 +3626,14 @@ png_log16bit(png_uint_32 x)
    /* Safe, because the result can't have more than 20 bits: */
    return (png_int_32)((lg2 + 2048) >> 12);
 }
+#endif /* 16BIT */
 
 /* The 'exp()' case must invert the above, taking a 20-bit fixed point
  * logarithmic value and returning a 16 or 8-bit number as appropriate.  In
  * each case only the low 16 bits are relevant - the fraction - since the
  * integer bits (the top 4) simply determine a shift.
  *
- * The worst case is the 16-bit distinction between 65535 and 65534, this
+ * The worst case is the 16-bit distinction between 65535 and 65534. This
  * requires perhaps spurious accuracy in the decoding of the logarithm to
  * distinguish log2(65535/65534.5) - 10^-5 or 17 bits.  There is little chance
  * of getting this accuracy in practice.
@@ -2347,21 +3642,17 @@ png_log16bit(png_uint_32 x)
  * frational part of the logarithm by using an accurate 32-bit value from the
  * top four fractional bits then multiplying in the remaining bits.
  */
-static png_uint_32
+static const png_uint_32
 png_32bit_exp[16] =
 {
-#  ifdef PNG_DO_BC
-      for (i=0;i<16;++i) { .5 + e(-i/16*l(2))*2^32; }
-#  else
    /* NOTE: the first entry is deliberately set to the maximum 32-bit value. */
    4294967295U, 4112874773U, 3938502376U, 3771522796U, 3611622603U, 3458501653U,
    3311872529U, 3171459999U, 3037000500U, 2908241642U, 2784941738U, 2666869345U,
    2553802834U, 2445529972U, 2341847524U, 2242560872U
-#  endif
 };
 
 /* Adjustment table; provided to explain the numbers in the code below. */
-#ifdef PNG_DO_BC
+#if 0
 for (i=11;i>=0;--i){ print i, " ", (1 - e(-(2^i)/65536*l(2))) * 2^(32-i), "\n"}
    11 44937.64284865548751208448
    10 45180.98734845585101160448
@@ -2377,7 +3668,7 @@ for (i=11;i>=0;--i){ print i, " ", (1 - e(-(2^i)/65536*l(2))) * 2^(32-i), "\n"}
     0 45425.85339951654943850496
 #endif
 
-PNG_STATIC png_uint_32
+static png_uint_32
 png_exp(png_fixed_point x)
 {
    if (x > 0 && x <= 0xfffff) /* Else overflow or zero (underflow) */
@@ -2425,21 +3716,22 @@ png_exp(png_fixed_point x)
    return 0;
 }
 
-PNG_STATIC png_byte
+static png_byte
 png_exp8bit(png_fixed_point lg2)
 {
    /* Get a 32-bit value: */
    png_uint_32 x = png_exp(lg2);
 
-   /* Convert the 32-bit value to 0..255 by multiplying by 256-1, note that the
+   /* Convert the 32-bit value to 0..255 by multiplying by 256-1. Note that the
     * second, rounding, step can't overflow because of the first, subtraction,
     * step.
     */
    x -= x >> 8;
-   return (png_byte)((x + 0x7fffffU) >> 24);
+   return (png_byte)(((x + 0x7fffffU) >> 24) & 0xff);
 }
 
-PNG_STATIC png_uint_16
+#ifdef PNG_16BIT_SUPPORTED
+static png_uint_16
 png_exp16bit(png_fixed_point lg2)
 {
    /* Get a 32-bit value: */
@@ -2449,6 +3741,7 @@ png_exp16bit(png_fixed_point lg2)
    x -= x >> 16;
    return (png_uint_16)((x + 32767U) >> 16);
 }
+#endif /* 16BIT */
 #endif /* FLOATING_ARITHMETIC */
 
 png_byte
@@ -2457,13 +3750,37 @@ png_gamma_8bit_correct(unsigned int value, png_fixed_point gamma_val)
    if (value > 0 && value < 255)
    {
 #     ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
-         double r = floor(255*pow(value/255.,gamma_val*.00001)+.5);
+         /* 'value' is unsigned, ANSI-C90 requires the compiler to correctly
+          * convert this to a floating point value.  This includes values that
+          * would overflow if 'value' were to be converted to 'int'.
+          *
+          * Apparently GCC, however, does an intermediate conversion to (int)
+          * on some (ARM) but not all (x86) platforms, possibly because of
+          * hardware FP limitations.  (E.g. if the hardware conversion always
+          * assumes the integer register contains a signed value.)  This results
+          * in ANSI-C undefined behavior for large values.
+          *
+          * Other implementations on the same machine might actually be ANSI-C90
+          * conformant and therefore compile spurious extra code for the large
+          * values.
+          *
+          * We can be reasonably sure that an unsigned to float conversion
+          * won't be faster than an int to float one.  Therefore this code
+          * assumes responsibility for the undefined behavior, which it knows
+          * can't happen because of the check above.
+          *
+          * Note the argument to this routine is an (unsigned int) because, on
+          * 16-bit platforms, it is assigned a value which might be out of
+          * range for an (int); that would result in undefined behavior in the
+          * caller if the *argument* ('value') were to be declared (int).
+          */
+         double r = floor(255*pow((int)/*SAFE*/value/255.,gamma_val*.00001)+.5);
          return (png_byte)r;
 #     else
          png_int_32 lg2 = png_log8bit(value);
          png_fixed_point res;
 
-         if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1))
+         if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1) != 0)
             return png_exp8bit(res);
 
          /* Overflow. */
@@ -2471,22 +3788,29 @@ png_gamma_8bit_correct(unsigned int value, png_fixed_point gamma_val)
 #     endif
    }
 
-   return (png_byte)value;
+   return (png_byte)(value & 0xff);
 }
 
+#ifdef PNG_16BIT_SUPPORTED
 png_uint_16
 png_gamma_16bit_correct(unsigned int value, png_fixed_point gamma_val)
 {
    if (value > 0 && value < 65535)
    {
 #     ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
-         double r = floor(65535*pow(value/65535.,gamma_val*.00001)+.5);
+         /* The same (unsigned int)->(double) constraints apply here as above,
+          * however in this case the (unsigned int) to (int) conversion can
+          * overflow on an ANSI-C90 compliant system so the cast needs to ensure
+          * that this is not possible.
+          */
+         double r = floor(65535*pow((png_int_32)value/65535.,
+                     gamma_val*.00001)+.5);
          return (png_uint_16)r;
 #     else
          png_int_32 lg2 = png_log16bit(value);
          png_fixed_point res;
 
-         if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1))
+         if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1) != 0)
             return png_exp16bit(res);
 
          /* Overflow. */
@@ -2496,6 +3820,7 @@ png_gamma_16bit_correct(unsigned int value, png_fixed_point gamma_val)
 
    return (png_uint_16)value;
 }
+#endif /* 16BIT */
 
 /* This does the right thing based on the bit_depth field of the
  * png_struct, interpreting values as 8-bit or 16-bit.  While the result
@@ -2503,28 +3828,24 @@ png_gamma_16bit_correct(unsigned int value, png_fixed_point gamma_val)
  * 8-bit (as are the arguments.)
  */
 png_uint_16 /* PRIVATE */
-png_gamma_correct(png_structp png_ptr, unsigned int value,
+png_gamma_correct(png_structrp png_ptr, unsigned int value,
     png_fixed_point gamma_val)
 {
    if (png_ptr->bit_depth == 8)
       return png_gamma_8bit_correct(value, gamma_val);
 
+#ifdef PNG_16BIT_SUPPORTED
    else
       return png_gamma_16bit_correct(value, gamma_val);
+#else
+      /* should not reach this */
+      return 0;
+#endif /* 16BIT */
 }
 
-/* This is the shared test on whether a gamma value is 'significant' - whether
- * it is worth doing gamma correction.
- */
-int /* PRIVATE */
-png_gamma_significant(png_fixed_point gamma_val)
-{
-   return gamma_val < PNG_FP_1 - PNG_GAMMA_THRESHOLD_FIXED ||
-       gamma_val > PNG_FP_1 + PNG_GAMMA_THRESHOLD_FIXED;
-}
-
+#ifdef PNG_16BIT_SUPPORTED
 /* Internal function to build a single 16-bit table - the table consists of
- * 'num' 256-entry subtables, where 'num' is determined by 'shift' - the amount
+ * 'num' 256 entry subtables, where 'num' is determined by 'shift' - the amount
  * to shift the input values right (or 16-number_of_signifiant_bits).
  *
  * The caller is responsible for ensuring that the table gets cleaned up on
@@ -2532,27 +3853,33 @@ png_gamma_significant(png_fixed_point gamma_val)
  * should be somewhere that will be cleaned.
  */
 static void
-png_build_16bit_table(png_structp png_ptr, png_uint_16pp *ptable,
+png_build_16bit_table(png_structrp png_ptr, png_uint_16pp *ptable,
    PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val)
 {
    /* Various values derived from 'shift': */
    PNG_CONST unsigned int num = 1U << (8U - shift);
+#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
+   /* CSE the division and work round wacky GCC warnings (see the comments
+    * in png_gamma_8bit_correct for where these come from.)
+    */
+   PNG_CONST double fmax = 1./(((png_int_32)1 << (16U - shift))-1);
+#endif
    PNG_CONST unsigned int max = (1U << (16U - shift))-1U;
    PNG_CONST unsigned int max_by_2 = 1U << (15U-shift);
    unsigned int i;
 
    png_uint_16pp table = *ptable =
-       (png_uint_16pp)png_calloc(png_ptr, num * png_sizeof(png_uint_16p));
+       (png_uint_16pp)png_calloc(png_ptr, num * (sizeof (png_uint_16p)));
 
    for (i = 0; i < num; i++)
    {
       png_uint_16p sub_table = table[i] =
-          (png_uint_16p)png_malloc(png_ptr, 256 * png_sizeof(png_uint_16));
+          (png_uint_16p)png_malloc(png_ptr, 256 * (sizeof (png_uint_16)));
 
       /* The 'threshold' test is repeated here because it can arise for one of
        * the 16-bit tables even if the others don't hit it.
        */
-      if (png_gamma_significant(gamma_val))
+      if (png_gamma_significant(gamma_val) != 0)
       {
          /* The old code would overflow at the end and this would cause the
           * 'pow' function to return a result >1, resulting in an
@@ -2568,10 +3895,13 @@ png_build_16bit_table(png_structp png_ptr, png_uint_16pp *ptable,
             png_uint_32 ig = (j << (8-shift)) + i;
 #           ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
                /* Inline the 'max' scaling operation: */
-               double d = floor(65535*pow(ig/(double)max, gamma_val*.00001)+.5);
+               /* See png_gamma_8bit_correct for why the cast to (int) is
+                * required here.
+                */
+               double d = floor(65535.*pow(ig*fmax, gamma_val*.00001)+.5);
                sub_table[j] = (png_uint_16)d;
 #           else
-               if (shift)
+               if (shift != 0)
                   ig = (ig * 65535U + max_by_2)/max;
 
                sub_table[j] = png_gamma_16bit_correct(ig, gamma_val);
@@ -2587,7 +3917,7 @@ png_build_16bit_table(png_structp png_ptr, png_uint_16pp *ptable,
          {
             png_uint_32 ig = (j << (8-shift)) + i;
 
-            if (shift)
+            if (shift != 0)
                ig = (ig * 65535U + max_by_2)/max;
 
             sub_table[j] = (png_uint_16)ig;
@@ -2600,7 +3930,7 @@ png_build_16bit_table(png_structp png_ptr, png_uint_16pp *ptable,
  * required.
  */
 static void
-png_build_16to8_table(png_structp png_ptr, png_uint_16pp *ptable,
+png_build_16to8_table(png_structrp png_ptr, png_uint_16pp *ptable,
    PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val)
 {
    PNG_CONST unsigned int num = 1U << (8U - shift);
@@ -2609,15 +3939,15 @@ png_build_16to8_table(png_structp png_ptr, png_uint_16pp *ptable,
    png_uint_32 last;
 
    png_uint_16pp table = *ptable =
-       (png_uint_16pp)png_calloc(png_ptr, num * png_sizeof(png_uint_16p));
+       (png_uint_16pp)png_calloc(png_ptr, num * (sizeof (png_uint_16p)));
 
-   /* 'num' is the number of tables and also the number of low bits of the
-    * input 16-bit value used to select a table.  Each table is itself indexed
-    * by the high 8 bits of the value.
+   /* 'num' is the number of tables and also the number of low bits of low
+    * bits of the input 16-bit value used to select a table.  Each table is
+    * itself indexed by the high 8 bits of the value.
     */
    for (i = 0; i < num; i++)
       table[i] = (png_uint_16p)png_malloc(png_ptr,
-          256 * png_sizeof(png_uint_16));
+          256 * (sizeof (png_uint_16)));
 
    /* 'gamma_val' is set to the reciprocal of the value calculated above, so
     * pow(out,g) is an *input* value.  'last' is the last input value set.
@@ -2661,34 +3991,38 @@ png_build_16to8_table(png_structp png_ptr, png_uint_16pp *ptable,
       last++;
    }
 }
+#endif /* 16BIT */
 
 /* Build a single 8-bit table: same as the 16-bit case but much simpler (and
  * typically much faster).  Note that libpng currently does no sBIT processing
  * (apparently contrary to the spec) so a 256-entry table is always generated.
  */
 static void
-png_build_8bit_table(png_structp png_ptr, png_bytepp ptable,
+png_build_8bit_table(png_structrp png_ptr, png_bytepp ptable,
    PNG_CONST png_fixed_point gamma_val)
 {
    unsigned int i;
    png_bytep table = *ptable = (png_bytep)png_malloc(png_ptr, 256);
 
-   if (png_gamma_significant(gamma_val)) for (i=0; i<256; i++)
-      table[i] = png_gamma_8bit_correct(i, gamma_val);
+   if (png_gamma_significant(gamma_val) != 0)
+      for (i=0; i<256; i++)
+         table[i] = png_gamma_8bit_correct(i, gamma_val);
 
-   else for (i=0; i<256; ++i)
-      table[i] = (png_byte)i;
+   else
+      for (i=0; i<256; ++i)
+         table[i] = (png_byte)(i & 0xff);
 }
 
 /* Used from png_read_destroy and below to release the memory used by the gamma
  * tables.
  */
 void /* PRIVATE */
-png_destroy_gamma_table(png_structp png_ptr)
+png_destroy_gamma_table(png_structrp png_ptr)
 {
    png_free(png_ptr, png_ptr->gamma_table);
    png_ptr->gamma_table = NULL;
 
+#ifdef PNG_16BIT_SUPPORTED
    if (png_ptr->gamma_16_table != NULL)
    {
       int i;
@@ -2700,6 +4034,7 @@ png_destroy_gamma_table(png_structp png_ptr)
    png_free(png_ptr, png_ptr->gamma_16_table);
    png_ptr->gamma_16_table = NULL;
    }
+#endif /* 16BIT */
 
 #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
    defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
@@ -2709,6 +4044,7 @@ png_destroy_gamma_table(png_structp png_ptr)
    png_free(png_ptr, png_ptr->gamma_to_1);
    png_ptr->gamma_to_1 = NULL;
 
+#ifdef PNG_16BIT_SUPPORTED
    if (png_ptr->gamma_16_from_1 != NULL)
    {
       int i;
@@ -2731,6 +4067,7 @@ png_destroy_gamma_table(png_structp png_ptr)
    png_free(png_ptr, png_ptr->gamma_16_to_1);
    png_ptr->gamma_16_to_1 = NULL;
    }
+#endif /* 16BIT */
 #endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
 }
 
@@ -2740,7 +4077,7 @@ png_destroy_gamma_table(png_structp png_ptr)
  * we don't need to allocate > 64K chunks for a full 16-bit table.
  */
 void /* PRIVATE */
-png_build_gamma_table(png_structp png_ptr, int bit_depth)
+png_build_gamma_table(png_structrp png_ptr, int bit_depth)
 {
   png_debug(1, "in png_build_gamma_table");
 
@@ -2759,28 +4096,29 @@ png_build_gamma_table(png_structp png_ptr, int bit_depth)
   if (bit_depth <= 8)
   {
      png_build_8bit_table(png_ptr, &png_ptr->gamma_table,
-         png_ptr->screen_gamma > 0 ?  png_reciprocal2(png_ptr->gamma,
+         png_ptr->screen_gamma > 0 ?  png_reciprocal2(png_ptr->colorspace.gamma,
          png_ptr->screen_gamma) : PNG_FP_1);
 
 #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
    defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
    defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
-     if (png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY))
+     if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0)
      {
         png_build_8bit_table(png_ptr, &png_ptr->gamma_to_1,
-            png_reciprocal(png_ptr->gamma));
+            png_reciprocal(png_ptr->colorspace.gamma));
 
         png_build_8bit_table(png_ptr, &png_ptr->gamma_from_1,
             png_ptr->screen_gamma > 0 ?  png_reciprocal(png_ptr->screen_gamma) :
-            png_ptr->gamma/* Probably doing rgb_to_gray */);
+            png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
      }
 #endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
   }
+#ifdef PNG_16BIT_SUPPORTED
   else
   {
      png_byte shift, sig_bit;
 
-     if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
+     if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
      {
         sig_bit = png_ptr->sig_bit.red;
 
@@ -2812,12 +4150,13 @@ png_build_gamma_table(png_structp png_ptr, int bit_depth)
       *
       */
      if (sig_bit > 0 && sig_bit < 16U)
-        shift = (png_byte)(16U - sig_bit); /* shift == insignificant bits */
+        /* shift == insignificant bits */
+        shift = (png_byte)((16U - sig_bit) & 0xff);
 
      else
         shift = 0; /* keep all 16 bits */
 
-     if (png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8))
+     if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
      {
         /* PNG_MAX_GAMMA_8 is the number of bits to keep - effectively
          * the significant bits in the *input* when the output will
@@ -2832,32 +4171,28 @@ png_build_gamma_table(png_structp png_ptr, int bit_depth)
 
      png_ptr->gamma_shift = shift;
 
-#ifdef PNG_16BIT_SUPPORTED
      /* NOTE: prior to 1.5.4 this test used to include PNG_BACKGROUND (now
       * PNG_COMPOSE).  This effectively smashed the background calculation for
       * 16-bit output because the 8-bit table assumes the result will be reduced
       * to 8 bits.
       */
-     if (png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8))
-#endif
+     if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
          png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift,
-         png_ptr->screen_gamma > 0 ? png_product2(png_ptr->gamma,
+         png_ptr->screen_gamma > 0 ? png_product2(png_ptr->colorspace.gamma,
          png_ptr->screen_gamma) : PNG_FP_1);
 
-#ifdef PNG_16BIT_SUPPORTED
      else
          png_build_16bit_table(png_ptr, &png_ptr->gamma_16_table, shift,
-         png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->gamma,
+         png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->colorspace.gamma,
          png_ptr->screen_gamma) : PNG_FP_1);
-#endif
 
 #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
    defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
    defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
-     if (png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY))
+     if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0)
      {
         png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift,
-            png_reciprocal(png_ptr->gamma));
+            png_reciprocal(png_ptr->colorspace.gamma));
 
         /* Notice that the '16 from 1' table should be full precision, however
          * the lookup on this table still uses gamma_shift, so it can't be.
@@ -2865,10 +4200,291 @@ png_build_gamma_table(png_structp png_ptr, int bit_depth)
          */
         png_build_16bit_table(png_ptr, &png_ptr->gamma_16_from_1, shift,
             png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
-            png_ptr->gamma/* Probably doing rgb_to_gray */);
+            png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
      }
 #endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
   }
+#endif /* 16BIT */
 }
 #endif /* READ_GAMMA */
-#endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
+
+/* HARDWARE OR SOFTWARE OPTION SUPPORT */
+#ifdef PNG_SET_OPTION_SUPPORTED
+int PNGAPI
+png_set_option(png_structrp png_ptr, int option, int onoff)
+{
+   if (png_ptr != NULL && option >= 0 && option < PNG_OPTION_NEXT &&
+      (option & 1) == 0)
+   {
+      int mask = 3 << option;
+      int setting = (2 + (onoff != 0)) << option;
+      int current = png_ptr->options;
+
+      png_ptr->options = (png_byte)(((current & ~mask) | setting) & 0xff);
+
+      return (current & mask) >> option;
+   }
+
+   return PNG_OPTION_INVALID;
+}
+#endif
+
+/* sRGB support */
+#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
+   defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
+/* sRGB conversion tables; these are machine generated with the code in
+ * contrib/tools/makesRGB.c.  The actual sRGB transfer curve defined in the
+ * specification (see the article at http://en.wikipedia.org/wiki/SRGB)
+ * is used, not the gamma=1/2.2 approximation use elsewhere in libpng.
+ * The sRGB to linear table is exact (to the nearest 16 bit linear fraction).
+ * The inverse (linear to sRGB) table has accuracies as follows:
+ *
+ * For all possible (255*65535+1) input values:
+ *
+ *    error: -0.515566 - 0.625971, 79441 (0.475369%) of readings inexact
+ *
+ * For the input values corresponding to the 65536 16-bit values:
+ *
+ *    error: -0.513727 - 0.607759, 308 (0.469978%) of readings inexact
+ *
+ * In all cases the inexact readings are only off by one.
+ */
+
+#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
+/* The convert-to-sRGB table is only currently required for read. */
+const png_uint_16 png_sRGB_table[256] =
+{
+   0,20,40,60,80,99,119,139,
+   159,179,199,219,241,264,288,313,
+   340,367,396,427,458,491,526,562,
+   599,637,677,718,761,805,851,898,
+   947,997,1048,1101,1156,1212,1270,1330,
+   1391,1453,1517,1583,1651,1720,1790,1863,
+   1937,2013,2090,2170,2250,2333,2418,2504,
+   2592,2681,2773,2866,2961,3058,3157,3258,
+   3360,3464,3570,3678,3788,3900,4014,4129,
+   4247,4366,4488,4611,4736,4864,4993,5124,
+   5257,5392,5530,5669,5810,5953,6099,6246,
+   6395,6547,6700,6856,7014,7174,7335,7500,
+   7666,7834,8004,8177,8352,8528,8708,8889,
+   9072,9258,9445,9635,9828,10022,10219,10417,
+   10619,10822,11028,11235,11446,11658,11873,12090,
+   12309,12530,12754,12980,13209,13440,13673,13909,
+   14146,14387,14629,14874,15122,15371,15623,15878,
+   16135,16394,16656,16920,17187,17456,17727,18001,
+   18277,18556,18837,19121,19407,19696,19987,20281,
+   20577,20876,21177,21481,21787,22096,22407,22721,
+   23038,23357,23678,24002,24329,24658,24990,25325,
+   25662,26001,26344,26688,27036,27386,27739,28094,
+   28452,28813,29176,29542,29911,30282,30656,31033,
+   31412,31794,32179,32567,32957,33350,33745,34143,
+   34544,34948,35355,35764,36176,36591,37008,37429,
+   37852,38278,38706,39138,39572,40009,40449,40891,
+   41337,41785,42236,42690,43147,43606,44069,44534,
+   45002,45473,45947,46423,46903,47385,47871,48359,
+   48850,49344,49841,50341,50844,51349,51858,52369,
+   52884,53401,53921,54445,54971,55500,56032,56567,
+   57105,57646,58190,58737,59287,59840,60396,60955,
+   61517,62082,62650,63221,63795,64372,64952,65535
+};
+#endif /* SIMPLIFIED_READ */
+
+/* The base/delta tables are required for both read and write (but currently
+ * only the simplified versions.)
+ */
+const png_uint_16 png_sRGB_base[512] =
+{
+   128,1782,3383,4644,5675,6564,7357,8074,
+   8732,9346,9921,10463,10977,11466,11935,12384,
+   12816,13233,13634,14024,14402,14769,15125,15473,
+   15812,16142,16466,16781,17090,17393,17690,17981,
+   18266,18546,18822,19093,19359,19621,19879,20133,
+   20383,20630,20873,21113,21349,21583,21813,22041,
+   22265,22487,22707,22923,23138,23350,23559,23767,
+   23972,24175,24376,24575,24772,24967,25160,25352,
+   25542,25730,25916,26101,26284,26465,26645,26823,
+   27000,27176,27350,27523,27695,27865,28034,28201,
+   28368,28533,28697,28860,29021,29182,29341,29500,
+   29657,29813,29969,30123,30276,30429,30580,30730,
+   30880,31028,31176,31323,31469,31614,31758,31902,
+   32045,32186,32327,32468,32607,32746,32884,33021,
+   33158,33294,33429,33564,33697,33831,33963,34095,
+   34226,34357,34486,34616,34744,34873,35000,35127,
+   35253,35379,35504,35629,35753,35876,35999,36122,
+   36244,36365,36486,36606,36726,36845,36964,37083,
+   37201,37318,37435,37551,37668,37783,37898,38013,
+   38127,38241,38354,38467,38580,38692,38803,38915,
+   39026,39136,39246,39356,39465,39574,39682,39790,
+   39898,40005,40112,40219,40325,40431,40537,40642,
+   40747,40851,40955,41059,41163,41266,41369,41471,
+   41573,41675,41777,41878,41979,42079,42179,42279,
+   42379,42478,42577,42676,42775,42873,42971,43068,
+   43165,43262,43359,43456,43552,43648,43743,43839,
+   43934,44028,44123,44217,44311,44405,44499,44592,
+   44685,44778,44870,44962,45054,45146,45238,45329,
+   45420,45511,45601,45692,45782,45872,45961,46051,
+   46140,46229,46318,46406,46494,46583,46670,46758,
+   46846,46933,47020,47107,47193,47280,47366,47452,
+   47538,47623,47709,47794,47879,47964,48048,48133,
+   48217,48301,48385,48468,48552,48635,48718,48801,
+   48884,48966,49048,49131,49213,49294,49376,49458,
+   49539,49620,49701,49782,49862,49943,50023,50103,
+   50183,50263,50342,50422,50501,50580,50659,50738,
+   50816,50895,50973,51051,51129,51207,51285,51362,
+   51439,51517,51594,51671,51747,51824,51900,51977,
+   52053,52129,52205,52280,52356,52432,52507,52582,
+   52657,52732,52807,52881,52956,53030,53104,53178,
+   53252,53326,53400,53473,53546,53620,53693,53766,
+   53839,53911,53984,54056,54129,54201,54273,54345,
+   54417,54489,54560,54632,54703,54774,54845,54916,
+   54987,55058,55129,55199,55269,55340,55410,55480,
+   55550,55620,55689,55759,55828,55898,55967,56036,
+   56105,56174,56243,56311,56380,56448,56517,56585,
+   56653,56721,56789,56857,56924,56992,57059,57127,
+   57194,57261,57328,57395,57462,57529,57595,57662,
+   57728,57795,57861,57927,57993,58059,58125,58191,
+   58256,58322,58387,58453,58518,58583,58648,58713,
+   58778,58843,58908,58972,59037,59101,59165,59230,
+   59294,59358,59422,59486,59549,59613,59677,59740,
+   59804,59867,59930,59993,60056,60119,60182,60245,
+   60308,60370,60433,60495,60558,60620,60682,60744,
+   60806,60868,60930,60992,61054,61115,61177,61238,
+   61300,61361,61422,61483,61544,61605,61666,61727,
+   61788,61848,61909,61969,62030,62090,62150,62211,
+   62271,62331,62391,62450,62510,62570,62630,62689,
+   62749,62808,62867,62927,62986,63045,63104,63163,
+   63222,63281,63340,63398,63457,63515,63574,63632,
+   63691,63749,63807,63865,63923,63981,64039,64097,
+   64155,64212,64270,64328,64385,64443,64500,64557,
+   64614,64672,64729,64786,64843,64900,64956,65013,
+   65070,65126,65183,65239,65296,65352,65409,65465
+};
+
+const png_byte png_sRGB_delta[512] =
+{
+   207,201,158,129,113,100,90,82,77,72,68,64,61,59,56,54,
+   52,50,49,47,46,45,43,42,41,40,39,39,38,37,36,36,
+   35,34,34,33,33,32,32,31,31,30,30,30,29,29,28,28,
+   28,27,27,27,27,26,26,26,25,25,25,25,24,24,24,24,
+   23,23,23,23,23,22,22,22,22,22,22,21,21,21,21,21,
+   21,20,20,20,20,20,20,20,20,19,19,19,19,19,19,19,
+   19,18,18,18,18,18,18,18,18,18,18,17,17,17,17,17,
+   17,17,17,17,17,17,16,16,16,16,16,16,16,16,16,16,
+   16,16,16,16,15,15,15,15,15,15,15,15,15,15,15,15,
+   15,15,15,15,14,14,14,14,14,14,14,14,14,14,14,14,
+   14,14,14,14,14,14,14,13,13,13,13,13,13,13,13,13,
+   13,13,13,13,13,13,13,13,13,13,13,13,13,13,12,12,
+   12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,
+   12,12,12,12,12,12,12,12,12,12,12,12,11,11,11,11,
+   11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,
+   11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,
+   11,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
+   10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
+   10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
+   10,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
+   9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
+   9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
+   9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
+   9,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
+   8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
+   8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
+   8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
+   8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
+   8,8,8,8,8,8,8,8,8,7,7,7,7,7,7,7,
+   7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+   7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+   7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
+};
+#endif /* SIMPLIFIED READ/WRITE sRGB support */
+
+/* SIMPLIFIED READ/WRITE SUPPORT */
+#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
+   defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
+static int
+png_image_free_function(png_voidp argument)
+{
+   png_imagep image = png_voidcast(png_imagep, argument);
+   png_controlp cp = image->opaque;
+   png_control c;
+
+   /* Double check that we have a png_ptr - it should be impossible to get here
+    * without one.
+    */
+   if (cp->png_ptr == NULL)
+      return 0;
+
+   /* First free any data held in the control structure. */
+#  ifdef PNG_STDIO_SUPPORTED
+      if (cp->owned_file != 0)
+      {
+         FILE *fp = png_voidcast(FILE*, cp->png_ptr->io_ptr);
+         cp->owned_file = 0;
+
+         /* Ignore errors here. */
+         if (fp != NULL)
+         {
+            cp->png_ptr->io_ptr = NULL;
+            (void)fclose(fp);
+         }
+      }
+#  endif
+
+   /* Copy the control structure so that the original, allocated, version can be
+    * safely freed.  Notice that a png_error here stops the remainder of the
+    * cleanup, but this is probably fine because that would indicate bad memory
+    * problems anyway.
+    */
+   c = *cp;
+   image->opaque = &c;
+   png_free(c.png_ptr, cp);
+
+   /* Then the structures, calling the correct API. */
+   if (c.for_write != 0)
+   {
+#     ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
+         png_destroy_write_struct(&c.png_ptr, &c.info_ptr);
+#     else
+         png_error(c.png_ptr, "simplified write not supported");
+#     endif
+   }
+   else
+   {
+#     ifdef PNG_SIMPLIFIED_READ_SUPPORTED
+         png_destroy_read_struct(&c.png_ptr, &c.info_ptr, NULL);
+#     else
+         png_error(c.png_ptr, "simplified read not supported");
+#     endif
+   }
+
+   /* Success. */
+   return 1;
+}
+
+void PNGAPI
+png_image_free(png_imagep image)
+{
+   /* Safely call the real function, but only if doing so is safe at this point
+    * (if not inside an error handling context).  Otherwise assume
+    * png_safe_execute will call this API after the return.
+    */
+   if (image != NULL && image->opaque != NULL &&
+      image->opaque->error_buf == NULL)
+   {
+      /* Ignore errors here: */
+      (void)png_safe_execute(image, png_image_free_function, image);
+      image->opaque = NULL;
+   }
+}
+
+int /* PRIVATE */
+png_image_error(png_imagep image, png_const_charp error_message)
+{
+   /* Utility to log an error. */
+   png_safecat(image->message, (sizeof image->message), 0, error_message);
+   image->warning_or_error |= PNG_IMAGE_ERROR;
+   png_image_free(image);
+   return 0;
+}
+
+#endif /* SIMPLIFIED READ/WRITE */
+#endif /* READ || WRITE */
diff --git a/src/3rdparty/libpng/png.h b/src/3rdparty/libpng/png.h
index 4e0dee1..372599b 100644
--- a/src/3rdparty/libpng/png.h
+++ b/src/3rdparty/libpng/png.h
@@ -1,8 +1,9 @@
 
 /* png.h - header file for PNG reference library
  *
- * libpng version 1.5.10 - March 29, 2012
- * Copyright (c) 1998-2012 Glenn Randers-Pehrson
+ * libpng version 1.6.17, March 26, 2015
+ *
+ * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
@@ -11,7 +12,7 @@
  * Authors and maintainers:
  *   libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
  *   libpng versions 0.89c, June 1996, through 0.96, May 1997: Andreas Dilger
- *   libpng versions 0.97, January 1998, through 1.5.10 - March 29, 2012: Glenn
+ *   libpng versions 0.97, January 1998, through 1.6.17, March 26, 2015: Glenn
  *   See also "Contributing Authors", below.
  *
  * Note about libpng version numbers:
@@ -166,14 +167,55 @@
  *    1.5.7beta01-05          15    10507  15.so.15.7[.0]
  *    1.5.7rc01-03            15    10507  15.so.15.7[.0]
  *    1.5.7                   15    10507  15.so.15.7[.0]
- *    1.5.8beta01             15    10508  15.so.15.8[.0]
- *    1.5.8rc01               15    10508  15.so.15.8[.0]
- *    1.5.8                   15    10508  15.so.15.8[.0]
- *    1.5.9beta01-02          15    10509  15.so.15.9[.0]
- *    1.5.9rc01               15    10509  15.so.15.9[.0]
- *    1.5.9                   15    10509  15.so.15.9[.0]
- *    1.5.10beta01-05         15    10510  15.so.15.10[.0]
- *    1.5.10                  15    10510  15.so.15.10[.0]
+ *    1.6.0beta01-40          16    10600  16.so.16.0[.0]
+ *    1.6.0rc01-08            16    10600  16.so.16.0[.0]
+ *    1.6.0                   16    10600  16.so.16.0[.0]
+ *    1.6.1beta01-09          16    10601  16.so.16.1[.0]
+ *    1.6.1rc01               16    10601  16.so.16.1[.0]
+ *    1.6.1                   16    10601  16.so.16.1[.0]
+ *    1.6.2beta01             16    10602  16.so.16.2[.0]
+ *    1.6.2rc01-06            16    10602  16.so.16.2[.0]
+ *    1.6.2                   16    10602  16.so.16.2[.0]
+ *    1.6.3beta01-11          16    10603  16.so.16.3[.0]
+ *    1.6.3rc01               16    10603  16.so.16.3[.0]
+ *    1.6.3                   16    10603  16.so.16.3[.0]
+ *    1.6.4beta01-02          16    10604  16.so.16.4[.0]
+ *    1.6.4rc01               16    10604  16.so.16.4[.0]
+ *    1.6.4                   16    10604  16.so.16.4[.0]
+ *    1.6.5                   16    10605  16.so.16.5[.0]
+ *    1.6.6                   16    10606  16.so.16.6[.0]
+ *    1.6.7beta01-04          16    10607  16.so.16.7[.0]
+ *    1.6.7rc01-03            16    10607  16.so.16.7[.0]
+ *    1.6.7                   16    10607  16.so.16.7[.0]
+ *    1.6.8beta01-02          16    10608  16.so.16.8[.0]
+ *    1.6.8rc01-02            16    10608  16.so.16.8[.0]
+ *    1.6.8                   16    10608  16.so.16.8[.0]
+ *    1.6.9beta01-04          16    10609  16.so.16.9[.0]
+ *    1.6.9rc01-02            16    10609  16.so.16.9[.0]
+ *    1.6.9                   16    10609  16.so.16.9[.0]
+ *    1.6.10beta01-03         16    10610  16.so.16.10[.0]
+ *    1.6.10rc01-03           16    10610  16.so.16.10[.0]
+ *    1.6.10                  16    10610  16.so.16.10[.0]
+ *    1.6.11beta01-06         16    10611  16.so.16.11[.0]
+ *    1.6.11rc01-02           16    10611  16.so.16.11[.0]
+ *    1.6.11                  16    10611  16.so.16.11[.0]
+ *    1.6.12rc01-03           16    10612  16.so.16.12[.0]
+ *    1.6.12                  16    10612  16.so.16.12[.0]
+ *    1.6.13beta01-04         16    10613  16.so.16.13[.0]
+ *    1.6.13rc01-02           16    10613  16.so.16.13[.0]
+ *    1.6.13                  16    10613  16.so.16.13[.0]
+ *    1.6.14beta01-07         16    10614  16.so.16.14[.0]
+ *    1.6.14rc01-02           16    10614  16.so.16.14[.0]
+ *    1.6.14                  16    10614  16.so.16.14[.0]
+ *    1.6.15beta01-08         16    10615  16.so.16.15[.0]
+ *    1.6.15rc01-03           16    10615  16.so.16.15[.0]
+ *    1.6.15                  16    10615  16.so.16.15[.0]
+ *    1.6.16beta01-03         16    10616  16.so.16.16[.0]
+ *    1.6.16rc01-02           16    10616  16.so.16.16[.0]
+ *    1.6.16                  16    10616  16.so.16.16[.0]
+ *    1.6.17beta01-06         16    10617  16.so.16.17[.0]
+ *    1.6.17rc01-06           16    10617  16.so.16.17[.0]
+ *    1.6.17                  16    10617  16.so.16.17[.0]
  *
  *   Henceforth the source version will match the shared-library major
  *   and minor numbers; the shared-library major version number will be
@@ -205,8 +247,8 @@
  *
  * This code is released under the libpng license.
  *
- * libpng versions 1.2.6, August 15, 2004, through 1.5.10, March 29, 2012, are
- * Copyright (c) 2004, 2006-2012 Glenn Randers-Pehrson, and are
+ * libpng versions 1.2.6, August 15, 2004, through 1.6.17, March 26, 2015, are
+ * Copyright (c) 2004, 2006-2015 Glenn Randers-Pehrson, and are
  * distributed according to the same disclaimer and license as libpng-1.2.5
  * with the following individual added to the list of Contributing Authors:
  *
@@ -317,28 +359,30 @@
  * Y2K compliance in libpng:
  * =========================
  *
- *    March 29, 2012
+ *    March 26, 2015
  *
  *    Since the PNG Development group is an ad-hoc body, we can't make
  *    an official declaration.
  *
  *    This is your unofficial assurance that libpng from version 0.71 and
- *    upward through 1.5.10 are Y2K compliant.  It is my belief that
+ *    upward through 1.6.17 are Y2K compliant.  It is my belief that
  *    earlier versions were also Y2K compliant.
  *
  *    Libpng only has two year fields.  One is a 2-byte unsigned integer
- *    that will hold years up to 65535.  The other holds the date in text
- *    format, and will hold years up to 9999.
+ *    that will hold years up to 65535.  The other, which is deprecated,
+ *    holds the date in text format, and will hold years up to 9999.
  *
  *    The integer is
  *        "png_uint_16 year" in png_time_struct.
  *
  *    The string is
- *        "png_char time_buffer" in png_struct
+ *        "char time_buffer[29]" in png_struct.  This is no longer used
+ *    in libpng-1.6.x and will be removed from libpng-1.7.0.
  *
  *    There are seven time-related functions:
- *        png.c: png_convert_to_rfc_1123() in png.c
- *          (formerly png_convert_to_rfc_1152() in error)
+ *        png.c: png_convert_to_rfc_1123_buffer() in png.c
+ *          (formerly png_convert_to_rfc_1123() prior to libpng-1.5.x and
+ *          png_convert_to_rfc_1152() in error prior to libpng-0.98)
  *        png_convert_from_struct_tm() in pngwrite.c, called in pngwrite.c
  *        png_convert_from_time_t() in pngwrite.c
  *        png_get_tIME() in pngget.c
@@ -349,8 +393,8 @@
  *    All handle dates properly in a Y2K environment.  The
  *    png_convert_from_time_t() function calls gmtime() to convert from system
  *    clock time, which returns (year - 1900), which we properly convert to
- *    the full 4-digit year.  There is a possibility that applications using
- *    libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
+ *    the full 4-digit year.  There is a possibility that libpng applications
+ *    are not passing 4-digit years into the png_convert_to_rfc_1123_buffer()
  *    function, or that they are incorrectly passing only a 2-digit year
  *    instead of "year - 1900" into the png_convert_from_struct_tm() function,
  *    but this is not under our control.  The libpng documentation has always
@@ -374,24 +418,26 @@
 /* This is not the place to learn how to use libpng. The file libpng-manual.txt
  * describes how to use libpng, and the file example.c summarizes it
  * with some code on which to build.  This file is useful for looking
- * at the actual function definitions and structure components.
+ * at the actual function definitions and structure components.  If that
+ * file has been stripped from your copy of libpng, you can find it at
+ * <http://www.libpng.org/pub/png/libpng-manual.txt>
  *
  * If you just need to read a PNG file and don't want to read the documentation
  * skip to the end of this file and read the section entitled 'simplified API'.
  */
 
 /* Version information for png.h - this should match the version in png.c */
-#define PNG_LIBPNG_VER_STRING "1.5.10"
+#define PNG_LIBPNG_VER_STRING "1.6.17"
 #define PNG_HEADER_VERSION_STRING \
-     " libpng version 1.5.10 - March 29, 2012\n"
+     " libpng version 1.6.17 - March 26, 2015\n"
 
-#define PNG_LIBPNG_VER_SONUM   15
-#define PNG_LIBPNG_VER_DLLNUM  15
+#define PNG_LIBPNG_VER_SONUM   16
+#define PNG_LIBPNG_VER_DLLNUM  16
 
 /* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */
 #define PNG_LIBPNG_VER_MAJOR   1
-#define PNG_LIBPNG_VER_MINOR   5
-#define PNG_LIBPNG_VER_RELEASE 10
+#define PNG_LIBPNG_VER_MINOR   6
+#define PNG_LIBPNG_VER_RELEASE 17
 
 /* This should match the numeric part of the final component of
  * PNG_LIBPNG_VER_STRING, omitting any leading zero:
@@ -422,7 +468,7 @@
  * version 1.0.0 was mis-numbered 100 instead of 10000).  From
  * version 1.0.1 it's    xxyyzz, where x=major, y=minor, z=release
  */
-#define PNG_LIBPNG_VER 10510 /* 1.5.10 */
+#define PNG_LIBPNG_VER 10617 /* 1.6.17 */
 
 /* Library configuration: these options cannot be changed after
  * the library has been built.
@@ -435,25 +481,7 @@
 #endif
 
 #ifndef PNG_VERSION_INFO_ONLY
-#  ifndef PNG_BUILDING_SYMBOL_TABLE
-  /*
-   *   Standard header files (not needed for the version info or while
-   *   building symbol table -- see scripts/pnglibconf.dfa)
-   */
-#    ifdef PNG_SETJMP_SUPPORTED
-#      include <setjmp.h>
-#    endif
-
-    /* Need the time information for converting tIME chunks, it
-     * defines struct tm:
-     */
-#    ifdef PNG_CONVERT_tIME_SUPPORTED
-       /* "time.h" functions are not supported on all operating systems */
-#      include <time.h>
-#    endif
-#  endif
-
-/* Machine specific configuration. */
+   /* Machine specific configuration. */
 #  include "pngconf.h"
 #endif
 
@@ -502,6 +530,7 @@ extern "C" {
  * 2. Type definitions (base types are defined in pngconf.h), structure
  *    definitions.
  * 3. Exported library functions.
+ * 4. Simplified API.
  *
  * The library source code has additional files (principally pngpriv.h) that
  * allow configuration of the library.
@@ -544,7 +573,48 @@ extern "C" {
 /* This triggers a compiler error in png.c, if png.c and png.h
  * do not agree upon the version number.
  */
-typedef char* png_libpng_version_1_5_10;
+typedef char* png_libpng_version_1_6_17;
+
+/* Basic control structions.  Read libpng-manual.txt or libpng.3 for more info.
+ *
+ * png_struct is the cache of information used while reading or writing a single
+ * PNG file.  One of these is always required, although the simplified API
+ * (below) hides the creation and destruction of it.
+ */
+typedef struct png_struct_def png_struct;
+typedef const png_struct * png_const_structp;
+typedef png_struct * png_structp;
+typedef png_struct * * png_structpp;
+
+/* png_info contains information read from or to be written to a PNG file.  One
+ * or more of these must exist while reading or creating a PNG file.  The
+ * information is not used by libpng during read but is used to control what
+ * gets written when a PNG file is created.  "png_get_" function calls read
+ * information during read and "png_set_" functions calls write information
+ * when creating a PNG.
+ * been moved into a separate header file that is not accessible to
+ * applications.  Read libpng-manual.txt or libpng.3 for more info.
+ */
+typedef struct png_info_def png_info;
+typedef png_info * png_infop;
+typedef const png_info * png_const_infop;
+typedef png_info * * png_infopp;
+
+/* Types with names ending 'p' are pointer types.  The corresponding types with
+ * names ending 'rp' are identical pointer types except that the pointer is
+ * marked 'restrict', which means that it is the only pointer to the object
+ * passed to the function.  Applications should not use the 'restrict' types;
+ * it is always valid to pass 'p' to a pointer with a function argument of the
+ * corresponding 'rp' type.  Different compilers have different rules with
+ * regard to type matching in the presence of 'restrict'.  For backward
+ * compatibility libpng callbacks never have 'restrict' in their parameters and,
+ * consequentially, writing portable application code is extremely difficult if
+ * an attempt is made to use 'restrict'.
+ */
+typedef png_struct * PNG_RESTRICT png_structrp;
+typedef const png_struct * PNG_RESTRICT png_const_structrp;
+typedef png_info * PNG_RESTRICT png_inforp;
+typedef const png_info * PNG_RESTRICT png_const_inforp;
 
 /* Three color definitions.  The order of the red, green, and blue, (and the
  * exact size) is not important, although the size of the fields need to
@@ -556,9 +626,9 @@ typedef struct png_color_struct
    png_byte green;
    png_byte blue;
 } png_color;
-typedef png_color FAR * png_colorp;
-typedef PNG_CONST png_color FAR * png_const_colorp;
-typedef png_color FAR * FAR * png_colorpp;
+typedef png_color * png_colorp;
+typedef const png_color * png_const_colorp;
+typedef png_color * * png_colorpp;
 
 typedef struct png_color_16_struct
 {
@@ -568,9 +638,9 @@ typedef struct png_color_16_struct
    png_uint_16 blue;
    png_uint_16 gray;  /* for use in grayscale files */
 } png_color_16;
-typedef png_color_16 FAR * png_color_16p;
-typedef PNG_CONST png_color_16 FAR * png_const_color_16p;
-typedef png_color_16 FAR * FAR * png_color_16pp;
+typedef png_color_16 * png_color_16p;
+typedef const png_color_16 * png_const_color_16p;
+typedef png_color_16 * * png_color_16pp;
 
 typedef struct png_color_8_struct
 {
@@ -580,9 +650,9 @@ typedef struct png_color_8_struct
    png_byte gray;  /* for use in grayscale files */
    png_byte alpha; /* for alpha channel files */
 } png_color_8;
-typedef png_color_8 FAR * png_color_8p;
-typedef PNG_CONST png_color_8 FAR * png_const_color_8p;
-typedef png_color_8 FAR * FAR * png_color_8pp;
+typedef png_color_8 * png_color_8p;
+typedef const png_color_8 * png_const_color_8p;
+typedef png_color_8 * * png_color_8pp;
 
 /*
  * The following two structures are used for the in-core representation
@@ -596,9 +666,9 @@ typedef struct png_sPLT_entry_struct
    png_uint_16 alpha;
    png_uint_16 frequency;
 } png_sPLT_entry;
-typedef png_sPLT_entry FAR * png_sPLT_entryp;
-typedef PNG_CONST png_sPLT_entry FAR * png_const_sPLT_entryp;
-typedef png_sPLT_entry FAR * FAR * png_sPLT_entrypp;
+typedef png_sPLT_entry * png_sPLT_entryp;
+typedef const png_sPLT_entry * png_const_sPLT_entryp;
+typedef png_sPLT_entry * * png_sPLT_entrypp;
 
 /*  When the depth of the sPLT palette is 8 bits, the color and alpha samples
  *  occupy the LSB of their respective members, and the MSB of each member
@@ -612,9 +682,9 @@ typedef struct png_sPLT_struct
    png_sPLT_entryp entries;  /* palette entries */
    png_int_32 nentries;      /* number of palette entries */
 } png_sPLT_t;
-typedef png_sPLT_t FAR * png_sPLT_tp;
-typedef PNG_CONST png_sPLT_t FAR * png_const_sPLT_tp;
-typedef png_sPLT_t FAR * FAR * png_sPLT_tpp;
+typedef png_sPLT_t * png_sPLT_tp;
+typedef const png_sPLT_t * png_const_sPLT_tp;
+typedef png_sPLT_t * * png_sPLT_tpp;
 
 #ifdef PNG_TEXT_SUPPORTED
 /* png_text holds the contents of a text/ztxt/itxt chunk in a PNG file,
@@ -651,9 +721,9 @@ typedef struct png_text_struct
    png_charp lang_key;     /* keyword translated UTF-8 string, 0 or more
                               chars or a NULL pointer */
 } png_text;
-typedef png_text FAR * png_textp;
-typedef PNG_CONST png_text FAR * png_const_textp;
-typedef png_text FAR * FAR * png_textpp;
+typedef png_text * png_textp;
+typedef const png_text * png_const_textp;
+typedef png_text * * png_textpp;
 #endif
 
 /* Supported compression types for text in PNG files (tEXt, and zTXt).
@@ -681,49 +751,45 @@ typedef struct png_time_struct
    png_byte minute;  /* minute of hour, 0 - 59 */
    png_byte second;  /* second of minute, 0 - 60 (for leap seconds) */
 } png_time;
-typedef png_time FAR * png_timep;
-typedef PNG_CONST png_time FAR * png_const_timep;
-typedef png_time FAR * FAR * png_timepp;
+typedef png_time * png_timep;
+typedef const png_time * png_const_timep;
+typedef png_time * * png_timepp;
 
-#if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED) || \
-    defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
+#if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) ||\
+   defined(PNG_USER_CHUNKS_SUPPORTED)
 /* png_unknown_chunk is a structure to hold queued chunks for which there is
  * no specific support.  The idea is that we can use this to queue
  * up private chunks for output even though the library doesn't actually
  * know about their semantics.
+ *
+ * The data in the structure is set by libpng on read and used on write.
  */
 typedef struct png_unknown_chunk_t
 {
-    png_byte name[5];
-    png_byte *data;
+    png_byte name[5]; /* Textual chunk name with '\0' terminator */
+    png_byte *data;   /* Data, should not be modified on read! */
     png_size_t size;
 
-    /* libpng-using applications should NOT directly modify this byte. */
+    /* On write 'location' must be set using the flag values listed below.
+     * Notice that on read it is set by libpng however the values stored have
+     * more bits set than are listed below.  Always treat the value as a
+     * bitmask.  On write set only one bit - setting multiple bits may cause the
+     * chunk to be written in multiple places.
+     */
     png_byte location; /* mode of operation at read time */
 }
-
-
 png_unknown_chunk;
-typedef png_unknown_chunk FAR * png_unknown_chunkp;
-typedef PNG_CONST png_unknown_chunk FAR * png_const_unknown_chunkp;
-typedef png_unknown_chunk FAR * FAR * png_unknown_chunkpp;
-#endif
 
-/* Values for the unknown chunk location byte */
+typedef png_unknown_chunk * png_unknown_chunkp;
+typedef const png_unknown_chunk * png_const_unknown_chunkp;
+typedef png_unknown_chunk * * png_unknown_chunkpp;
+#endif
 
+/* Flag values for the unknown chunk location byte. */
 #define PNG_HAVE_IHDR  0x01
 #define PNG_HAVE_PLTE  0x02
 #define PNG_AFTER_IDAT 0x08
 
-/* The complete definition of png_info has, as of libpng-1.5.0,
- * been moved into a separate header file that is not accessible to
- * applications.  Read libpng-manual.txt or libpng.3 for more info.
- */
-typedef struct png_info_def png_info;
-typedef png_info FAR * png_infop;
-typedef PNG_CONST png_info FAR * png_const_infop;
-typedef png_info FAR * FAR * png_infopp;
-
 /* Maximum positive integer used in PNG is (2^31)-1 */
 #define PNG_UINT_31_MAX ((png_uint_32)0x7fffffffL)
 #define PNG_UINT_32_MAX ((png_uint_32)(-1))
@@ -839,16 +905,8 @@ typedef struct png_row_info_struct
    png_byte pixel_depth; /* bits per pixel (depth * channels) */
 } png_row_info;
 
-typedef png_row_info FAR * png_row_infop;
-typedef png_row_info FAR * FAR * png_row_infopp;
-
-/* The complete definition of png_struct has, as of libpng-1.5.0,
- * been moved into a separate header file that is not accessible to
- * applications.  Read libpng-manual.txt or libpng.3 for more info.
- */
-typedef struct png_struct_def png_struct;
-typedef PNG_CONST png_struct FAR * png_const_structp;
-typedef png_struct FAR * png_structp;
+typedef png_row_info * png_row_infop;
+typedef png_row_info * * png_row_infopp;
 
 /* These are the function types for the I/O functions and for the functions
  * that allow the user to override the default I/O functions with his or her
@@ -895,7 +953,8 @@ typedef PNG_CALLBACK(int, *png_user_chunk_ptr, (png_structp,
     png_unknown_chunkp));
 #endif
 #ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
-typedef PNG_CALLBACK(void, *png_unknown_chunk_ptr, (png_structp));
+/* not used anywhere */
+/* typedef PNG_CALLBACK(void, *png_unknown_chunk_ptr, (png_structp)); */
 #endif
 
 #ifdef PNG_SETJMP_SUPPORTED
@@ -951,8 +1010,6 @@ typedef PNG_CALLBACK(png_voidp, *png_malloc_ptr, (png_structp,
     png_alloc_size_t));
 typedef PNG_CALLBACK(void, *png_free_ptr, (png_structp, png_voidp));
 
-typedef png_struct FAR * FAR * png_structpp;
-
 /* Section 3: exported functions
  * Here are the function definitions most commonly used.  This is not
  * the place to find out how to use libpng.  See libpng-manual.txt for the
@@ -988,7 +1045,7 @@ PNG_EXPORT(1, png_uint_32, png_access_version_number, (void));
 /* Tell lib we have already handled the first <num_bytes> magic bytes.
  * Handling more than 8 bytes from the beginning of the file is an error.
  */
-PNG_EXPORT(2, void, png_set_sig_bytes, (png_structp png_ptr, int num_bytes));
+PNG_EXPORT(2, void, png_set_sig_bytes, (png_structrp png_ptr, int num_bytes));
 
 /* Check sig[start] through sig[start + num_to_check - 1] to see if it's a
  * PNG file.  Returns zero if the supplied bytes match the 8-byte PNG
@@ -1016,9 +1073,9 @@ PNG_EXPORTA(5, png_structp, png_create_write_struct,
     PNG_ALLOCATED);
 
 PNG_EXPORT(6, png_size_t, png_get_compression_buffer_size,
-    (png_const_structp png_ptr));
+    (png_const_structrp png_ptr));
 
-PNG_EXPORT(7, void, png_set_compression_buffer_size, (png_structp png_ptr,
+PNG_EXPORT(7, void, png_set_compression_buffer_size, (png_structrp png_ptr,
     png_size_t size));
 
 /* Moved from pngconf.h in 1.4.0 and modified to ensure setjmp/longjmp
@@ -1032,10 +1089,10 @@ PNG_EXPORT(7, void, png_set_compression_buffer_size, (png_structp png_ptr,
  * allocated by the library - the call will return NULL on a mismatch
  * indicating an ABI mismatch.
  */
-PNG_EXPORT(8, jmp_buf*, png_set_longjmp_fn, (png_structp png_ptr,
+PNG_EXPORT(8, jmp_buf*, png_set_longjmp_fn, (png_structrp png_ptr,
     png_longjmp_ptr longjmp_fn, size_t jmp_buf_size));
 #  define png_jmpbuf(png_ptr) \
-      (*png_set_longjmp_fn((png_ptr), longjmp, sizeof (jmp_buf)))
+      (*png_set_longjmp_fn((png_ptr), longjmp, (sizeof (jmp_buf))))
 #else
 #  define png_jmpbuf(png_ptr) \
       (LIBPNG_WAS_COMPILED_WITH__PNG_NO_SETJMP)
@@ -1045,12 +1102,12 @@ PNG_EXPORT(8, jmp_buf*, png_set_longjmp_fn, (png_structp png_ptr,
  * will use it; otherwise it will call PNG_ABORT().  This function was
  * added in libpng-1.5.0.
  */
-PNG_EXPORTA(9, void, png_longjmp, (png_structp png_ptr, int val),
+PNG_EXPORTA(9, void, png_longjmp, (png_const_structrp png_ptr, int val),
     PNG_NORETURN);
 
 #ifdef PNG_READ_SUPPORTED
 /* Reset the compression stream */
-PNG_EXPORT(10, int, png_reset_zstream, (png_structp png_ptr));
+PNG_EXPORTA(10, int, png_reset_zstream, (png_structrp png_ptr), PNG_DEPRECATED);
 #endif
 
 /* New functions added in libpng-1.0.2 (not enabled by default until 1.2.0) */
@@ -1068,81 +1125,92 @@ PNG_EXPORTA(12, png_structp, png_create_write_struct_2,
 #endif
 
 /* Write the PNG file signature. */
-PNG_EXPORT(13, void, png_write_sig, (png_structp png_ptr));
+PNG_EXPORT(13, void, png_write_sig, (png_structrp png_ptr));
 
 /* Write a PNG chunk - size, type, (optional) data, CRC. */
-PNG_EXPORT(14, void, png_write_chunk, (png_structp png_ptr, png_const_bytep
+PNG_EXPORT(14, void, png_write_chunk, (png_structrp png_ptr, png_const_bytep
     chunk_name, png_const_bytep data, png_size_t length));
 
 /* Write the start of a PNG chunk - length and chunk name. */
-PNG_EXPORT(15, void, png_write_chunk_start, (png_structp png_ptr,
+PNG_EXPORT(15, void, png_write_chunk_start, (png_structrp png_ptr,
     png_const_bytep chunk_name, png_uint_32 length));
 
 /* Write the data of a PNG chunk started with png_write_chunk_start(). */
-PNG_EXPORT(16, void, png_write_chunk_data, (png_structp png_ptr,
+PNG_EXPORT(16, void, png_write_chunk_data, (png_structrp png_ptr,
     png_const_bytep data, png_size_t length));
 
 /* Finish a chunk started with png_write_chunk_start() (includes CRC). */
-PNG_EXPORT(17, void, png_write_chunk_end, (png_structp png_ptr));
+PNG_EXPORT(17, void, png_write_chunk_end, (png_structrp png_ptr));
 
 /* Allocate and initialize the info structure */
-PNG_EXPORTA(18, png_infop, png_create_info_struct, (png_structp png_ptr),
+PNG_EXPORTA(18, png_infop, png_create_info_struct, (png_const_structrp png_ptr),
     PNG_ALLOCATED);
 
-PNG_EXPORT(19, void, png_info_init_3, (png_infopp info_ptr,
-    png_size_t png_info_struct_size));
+/* DEPRECATED: this function allowed init structures to be created using the
+ * default allocation method (typically malloc).  Use is deprecated in 1.6.0 and
+ * the API will be removed in the future.
+ */
+PNG_EXPORTA(19, void, png_info_init_3, (png_infopp info_ptr,
+    png_size_t png_info_struct_size), PNG_DEPRECATED);
 
 /* Writes all the PNG information before the image. */
 PNG_EXPORT(20, void, png_write_info_before_PLTE,
-    (png_structp png_ptr, png_infop info_ptr));
+    (png_structrp png_ptr, png_const_inforp info_ptr));
 PNG_EXPORT(21, void, png_write_info,
-    (png_structp png_ptr, png_infop info_ptr));
+    (png_structrp png_ptr, png_const_inforp info_ptr));
 
 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 /* Read the information before the actual image data. */
 PNG_EXPORT(22, void, png_read_info,
-    (png_structp png_ptr, png_infop info_ptr));
+    (png_structrp png_ptr, png_inforp info_ptr));
 #endif
 
 #ifdef PNG_TIME_RFC1123_SUPPORTED
-PNG_EXPORT(23, png_const_charp, png_convert_to_rfc1123,
-    (png_structp png_ptr,
+   /* Convert to a US string format: there is no localization support in this
+    * routine.  The original implementation used a 29 character buffer in
+    * png_struct, this will be removed in future versions.
+    */
+#if PNG_LIBPNG_VER < 10700
+/* To do: remove this from libpng17 (and from libpng17/png.c and pngstruct.h) */
+PNG_EXPORTA(23, png_const_charp, png_convert_to_rfc1123, (png_structrp png_ptr,
+    png_const_timep ptime),PNG_DEPRECATED);
+#endif
+PNG_EXPORT(241, int, png_convert_to_rfc1123_buffer, (char out[29],
     png_const_timep ptime));
 #endif
 
 #ifdef PNG_CONVERT_tIME_SUPPORTED
 /* Convert from a struct tm to png_time */
 PNG_EXPORT(24, void, png_convert_from_struct_tm, (png_timep ptime,
-    PNG_CONST struct tm FAR * ttime));
+    const struct tm * ttime));
 
 /* Convert from time_t to png_time.  Uses gmtime() */
-PNG_EXPORT(25, void, png_convert_from_time_t,
-    (png_timep ptime, time_t ttime));
-#endif /* PNG_CONVERT_tIME_SUPPORTED */
+PNG_EXPORT(25, void, png_convert_from_time_t, (png_timep ptime, time_t ttime));
+#endif /* CONVERT_tIME */
 
 #ifdef PNG_READ_EXPAND_SUPPORTED
 /* Expand data to 24-bit RGB, or 8-bit grayscale, with alpha if available. */
-PNG_EXPORT(26, void, png_set_expand, (png_structp png_ptr));
-PNG_EXPORT(27, void, png_set_expand_gray_1_2_4_to_8, (png_structp png_ptr));
-PNG_EXPORT(28, void, png_set_palette_to_rgb, (png_structp png_ptr));
-PNG_EXPORT(29, void, png_set_tRNS_to_alpha, (png_structp png_ptr));
+PNG_EXPORT(26, void, png_set_expand, (png_structrp png_ptr));
+PNG_EXPORT(27, void, png_set_expand_gray_1_2_4_to_8, (png_structrp png_ptr));
+PNG_EXPORT(28, void, png_set_palette_to_rgb, (png_structrp png_ptr));
+PNG_EXPORT(29, void, png_set_tRNS_to_alpha, (png_structrp png_ptr));
 #endif
 
 #ifdef PNG_READ_EXPAND_16_SUPPORTED
 /* Expand to 16-bit channels, forces conversion of palette to RGB and expansion
  * of a tRNS chunk if present.
  */
-PNG_EXPORT(221, void, png_set_expand_16, (png_structp png_ptr));
+PNG_EXPORT(221, void, png_set_expand_16, (png_structrp png_ptr));
 #endif
 
 #if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
 /* Use blue, green, red order for pixels. */
-PNG_EXPORT(30, void, png_set_bgr, (png_structp png_ptr));
+PNG_EXPORT(30, void, png_set_bgr, (png_structrp png_ptr));
 #endif
 
 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
 /* Expand the grayscale to 24-bit RGB if necessary. */
-PNG_EXPORT(31, void, png_set_gray_to_rgb, (png_structp png_ptr));
+PNG_EXPORT(31, void, png_set_gray_to_rgb, (png_structrp png_ptr));
 #endif
 
 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
@@ -1152,12 +1220,12 @@ PNG_EXPORT(31, void, png_set_gray_to_rgb, (png_structp png_ptr));
 #define PNG_ERROR_ACTION_ERROR 3
 #define PNG_RGB_TO_GRAY_DEFAULT (-1)/*for red/green coefficients*/
 
-PNG_FP_EXPORT(32, void, png_set_rgb_to_gray, (png_structp png_ptr,
-    int error_action, double red, double green));
-PNG_FIXED_EXPORT(33, void, png_set_rgb_to_gray_fixed, (png_structp png_ptr,
-    int error_action, png_fixed_point red, png_fixed_point green));
+PNG_FP_EXPORT(32, void, png_set_rgb_to_gray, (png_structrp png_ptr,
+    int error_action, double red, double green))
+PNG_FIXED_EXPORT(33, void, png_set_rgb_to_gray_fixed, (png_structrp png_ptr,
+    int error_action, png_fixed_point red, png_fixed_point green))
 
-PNG_EXPORT(34, png_byte, png_get_rgb_to_gray_status, (png_const_structp
+PNG_EXPORT(34, png_byte, png_get_rgb_to_gray_status, (png_const_structrp
     png_ptr));
 #endif
 
@@ -1167,9 +1235,9 @@ PNG_EXPORT(35, void, png_build_grayscale_palette, (int bit_depth,
 #endif
 
 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
-/* How the alpha channel is interpreted - this affects how the color channels of
- * a PNG file are returned when an alpha channel, or tRNS chunk in a palette
- * file, is present.
+/* How the alpha channel is interpreted - this affects how the color channels
+ * of a PNG file are returned to the calling application when an alpha channel,
+ * or a tRNS chunk in a palette file, is present.
  *
  * This has no effect on the way pixels are written into a PNG output
  * datastream. The color samples in a PNG datastream are never premultiplied
@@ -1177,33 +1245,19 @@ PNG_EXPORT(35, void, png_build_grayscale_palette, (int bit_depth,
  *
  * The default is to return data according to the PNG specification: the alpha
  * channel is a linear measure of the contribution of the pixel to the
- * corresponding composited pixel.  The gamma encoded color channels must be
- * scaled according to the contribution and to do this it is necessary to undo
+ * corresponding composited pixel, and the color channels are unassociated
+ * (not premultiplied).  The gamma encoded color channels must be scaled
+ * according to the contribution and to do this it is necessary to undo
  * the encoding, scale the color values, perform the composition and reencode
  * the values.  This is the 'PNG' mode.
  *
  * The alternative is to 'associate' the alpha with the color information by
- * storing color channel values that have been scaled by the alpha.  The
- * advantage is that the color channels can be resampled (the image can be
- * scaled) in this form.  The disadvantage is that normal practice is to store
- * linear, not (gamma) encoded, values and this requires 16-bit channels for
- * still images rather than the 8-bit channels that are just about sufficient if
- * gamma encoding is used.  In addition all non-transparent pixel values,
- * including completely opaque ones, must be gamma encoded to produce the final
- * image.  This is the 'STANDARD', 'ASSOCIATED' or 'PREMULTIPLIED' mode (the
- * latter being the two common names for associated alpha color channels.)
- *
- * Since it is not necessary to perform arithmetic on opaque color values so
- * long as they are not to be resampled and are in the final color space it is
- * possible to optimize the handling of alpha by storing the opaque pixels in
- * the PNG format (adjusted for the output color space) while storing partially
- * opaque pixels in the standard, linear, format.  The accuracy required for
- * standard alpha composition is relatively low, because the pixels are
- * isolated, therefore typically the accuracy loss in storing 8-bit linear
- * values is acceptable.  (This is not true if the alpha channel is used to
- * simulate transparency over large areas - use 16 bits or the PNG mode in
- * this case!)  This is the 'OPTIMIZED' mode.  For this mode a pixel is
- * treated as opaque only if the alpha value is equal to the maximum value.
+ * storing color channel values that have been scaled by the alpha.
+ * image.  These are the 'STANDARD', 'ASSOCIATED' or 'PREMULTIPLIED' modes
+ * (the latter being the two common names for associated alpha color channels).
+ *
+ * For the 'OPTIMIZED' mode, a pixel is treated as opaque only if the alpha
+ * value is equal to the maximum value.
  *
  * The final choice is to gamma encode the alpha channel as well.  This is
  * broken because, in practice, no implementation that uses this choice
@@ -1222,76 +1276,15 @@ PNG_EXPORT(35, void, png_build_grayscale_palette, (int bit_depth,
 #define PNG_ALPHA_OPTIMIZED     2 /* 'PNG' for opaque pixels, else 'STANDARD' */
 #define PNG_ALPHA_BROKEN        3 /* the alpha channel is gamma encoded */
 
-PNG_FP_EXPORT(227, void, png_set_alpha_mode, (png_structp png_ptr, int mode,
-    double output_gamma));
-PNG_FIXED_EXPORT(228, void, png_set_alpha_mode_fixed, (png_structp png_ptr,
-    int mode, png_fixed_point output_gamma));
+PNG_FP_EXPORT(227, void, png_set_alpha_mode, (png_structrp png_ptr, int mode,
+    double output_gamma))
+PNG_FIXED_EXPORT(228, void, png_set_alpha_mode_fixed, (png_structrp png_ptr,
+    int mode, png_fixed_point output_gamma))
 #endif
 
-#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_ALPHA_MODE_SUPPORTED)
+#if defined(PNG_GAMMA_SUPPORTED) || defined(PNG_READ_ALPHA_MODE_SUPPORTED)
 /* The output_gamma value is a screen gamma in libpng terminology: it expresses
- * how to decode the output values, not how they are encoded.  The values used
- * correspond to the normal numbers used to describe the overall gamma of a
- * computer display system; for example 2.2 for an sRGB conformant system.  The
- * values are scaled by 100000 in the _fixed version of the API (so 220000 for
- * sRGB.)
- *
- * The inverse of the value is always used to provide a default for the PNG file
- * encoding if it has no gAMA chunk and if png_set_gamma() has not been called
- * to override the PNG gamma information.
- *
- * When the ALPHA_OPTIMIZED mode is selected the output gamma is used to encode
- * opaque pixels however pixels with lower alpha values are not encoded,
- * regardless of the output gamma setting.
- *
- * When the standard Porter Duff handling is requested with mode 1 the output
- * encoding is set to be linear and the output_gamma value is only relevant
- * as a default for input data that has no gamma information.  The linear output
- * encoding will be overridden if png_set_gamma() is called - the results may be
- * highly unexpected!
- *
- * The following numbers are derived from the sRGB standard and the research
- * behind it.  sRGB is defined to be approximated by a PNG gAMA chunk value of
- * 0.45455 (1/2.2) for PNG.  The value implicitly includes any viewing
- * correction required to take account of any differences in the color
- * environment of the original scene and the intended display environment; the
- * value expresses how to *decode* the image for display, not how the original
- * data was *encoded*.
- *
- * sRGB provides a peg for the PNG standard by defining a viewing environment.
- * sRGB itself, and earlier TV standards, actually use a more complex transform
- * (a linear portion then a gamma 2.4 power law) than PNG can express.  (PNG is
- * limited to simple power laws.)  By saying that an image for direct display on
- * an sRGB conformant system should be stored with a gAMA chunk value of 45455
- * (11.3.3.2 and 11.3.3.5 of the ISO PNG specification) the PNG specification
- * makes it possible to derive values for other display systems and
- * environments.
- *
- * The Mac value is deduced from the sRGB based on an assumption that the actual
- * extra viewing correction used in early Mac display systems was implemented as
- * a power 1.45 lookup table.
- *
- * Any system where a programmable lookup table is used or where the behavior of
- * the final display device characteristics can be changed requires system
- * specific code to obtain the current characteristic.  However this can be
- * difficult and most PNG gamma correction only requires an approximate value.
- *
- * By default, if png_set_alpha_mode() is not called, libpng assumes that all
- * values are unencoded, linear, values and that the output device also has a
- * linear characteristic.  This is only very rarely correct - it is invariably
- * better to call png_set_alpha_mode() with PNG_DEFAULT_sRGB than rely on the
- * default if you don't know what the right answer is!
- *
- * The special value PNG_GAMMA_MAC_18 indicates an older Mac system (pre Mac OS
- * 10.6) which used a correction table to implement a somewhat lower gamma on an
- * otherwise sRGB system.
- *
- * Both these values are reserved (not simple gamma values) in order to allow
- * more precise correction internally in the future.
- *
- * NOTE: the following values can be passed to either the fixed or floating
- * point APIs, but the floating point API will also accept floating point
- * values.
+ * how to decode the output values, not how they are encoded.
  */
 #define PNG_DEFAULT_sRGB -1       /* sRGB gamma and color space */
 #define PNG_GAMMA_MAC_18 -2       /* Old Mac '1.8' gamma and color space */
@@ -1376,51 +1369,50 @@ PNG_FIXED_EXPORT(228, void, png_set_alpha_mode_fixed, (png_structp png_ptr,
  */
 
 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
-PNG_EXPORT(36, void, png_set_strip_alpha, (png_structp png_ptr));
+PNG_EXPORT(36, void, png_set_strip_alpha, (png_structrp png_ptr));
 #endif
 
 #if defined(PNG_READ_SWAP_ALPHA_SUPPORTED) || \
     defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
-PNG_EXPORT(37, void, png_set_swap_alpha, (png_structp png_ptr));
+PNG_EXPORT(37, void, png_set_swap_alpha, (png_structrp png_ptr));
 #endif
 
 #if defined(PNG_READ_INVERT_ALPHA_SUPPORTED) || \
     defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
-PNG_EXPORT(38, void, png_set_invert_alpha, (png_structp png_ptr));
+PNG_EXPORT(38, void, png_set_invert_alpha, (png_structrp png_ptr));
 #endif
 
 #if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
 /* Add a filler byte to 8-bit Gray or 24-bit RGB images. */
-PNG_EXPORT(39, void, png_set_filler, (png_structp png_ptr, png_uint_32 filler,
+PNG_EXPORT(39, void, png_set_filler, (png_structrp png_ptr, png_uint_32 filler,
     int flags));
 /* The values of the PNG_FILLER_ defines should NOT be changed */
 #  define PNG_FILLER_BEFORE 0
 #  define PNG_FILLER_AFTER 1
 /* Add an alpha byte to 8-bit Gray or 24-bit RGB images. */
-PNG_EXPORT(40, void, png_set_add_alpha,
-    (png_structp png_ptr, png_uint_32 filler,
-    int flags));
-#endif /* PNG_READ_FILLER_SUPPORTED || PNG_WRITE_FILLER_SUPPORTED */
+PNG_EXPORT(40, void, png_set_add_alpha, (png_structrp png_ptr,
+    png_uint_32 filler, int flags));
+#endif /* READ_FILLER || WRITE_FILLER */
 
 #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
 /* Swap bytes in 16-bit depth files. */
-PNG_EXPORT(41, void, png_set_swap, (png_structp png_ptr));
+PNG_EXPORT(41, void, png_set_swap, (png_structrp png_ptr));
 #endif
 
 #if defined(PNG_READ_PACK_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED)
 /* Use 1 byte per pixel in 1, 2, or 4-bit depth files. */
-PNG_EXPORT(42, void, png_set_packing, (png_structp png_ptr));
+PNG_EXPORT(42, void, png_set_packing, (png_structrp png_ptr));
 #endif
 
 #if defined(PNG_READ_PACKSWAP_SUPPORTED) || \
     defined(PNG_WRITE_PACKSWAP_SUPPORTED)
 /* Swap packing order of pixels in bytes. */
-PNG_EXPORT(43, void, png_set_packswap, (png_structp png_ptr));
+PNG_EXPORT(43, void, png_set_packswap, (png_structrp png_ptr));
 #endif
 
 #if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)
 /* Converts files to legal bit depths. */
-PNG_EXPORT(44, void, png_set_shift, (png_structp png_ptr, png_const_color_8p
+PNG_EXPORT(44, void, png_set_shift, (png_structrp png_ptr, png_const_color_8p
     true_bits));
 #endif
 
@@ -1432,12 +1424,12 @@ PNG_EXPORT(44, void, png_set_shift, (png_structp png_ptr, png_const_color_8p
  * necessary to call png_read_row or png_read_rows png_get_image_height
  * times for each pass.
 */
-PNG_EXPORT(45, int, png_set_interlace_handling, (png_structp png_ptr));
+PNG_EXPORT(45, int, png_set_interlace_handling, (png_structrp png_ptr));
 #endif
 
 #if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
 /* Invert monochrome files */
-PNG_EXPORT(46, void, png_set_invert_mono, (png_structp png_ptr));
+PNG_EXPORT(46, void, png_set_invert_mono, (png_structrp png_ptr));
 #endif
 
 #ifdef PNG_READ_BACKGROUND_SUPPORTED
@@ -1446,12 +1438,12 @@ PNG_EXPORT(46, void, png_set_invert_mono, (png_structp png_ptr));
  * read.  Doing so will result in unexpected behavior and possible warnings or
  * errors if the PNG file contains a bKGD chunk.
  */
-PNG_FP_EXPORT(47, void, png_set_background, (png_structp png_ptr,
+PNG_FP_EXPORT(47, void, png_set_background, (png_structrp png_ptr,
     png_const_color_16p background_color, int background_gamma_code,
-    int need_expand, double background_gamma));
-PNG_FIXED_EXPORT(215, void, png_set_background_fixed, (png_structp png_ptr,
+    int need_expand, double background_gamma))
+PNG_FIXED_EXPORT(215, void, png_set_background_fixed, (png_structrp png_ptr,
     png_const_color_16p background_color, int background_gamma_code,
-    int need_expand, png_fixed_point background_gamma));
+    int need_expand, png_fixed_point background_gamma))
 #endif
 #ifdef PNG_READ_BACKGROUND_SUPPORTED
 #  define PNG_BACKGROUND_GAMMA_UNKNOWN 0
@@ -1462,23 +1454,22 @@ PNG_FIXED_EXPORT(215, void, png_set_background_fixed, (png_structp png_ptr,
 
 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
 /* Scale a 16-bit depth file down to 8-bit, accurately. */
-PNG_EXPORT(229, void, png_set_scale_16, (png_structp png_ptr));
+PNG_EXPORT(229, void, png_set_scale_16, (png_structrp png_ptr));
 #endif
 
 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
 #define PNG_READ_16_TO_8 SUPPORTED /* Name prior to 1.5.4 */
 /* Strip the second byte of information from a 16-bit depth file. */
-PNG_EXPORT(48, void, png_set_strip_16, (png_structp png_ptr));
+PNG_EXPORT(48, void, png_set_strip_16, (png_structrp png_ptr));
 #endif
 
 #ifdef PNG_READ_QUANTIZE_SUPPORTED
 /* Turn on quantizing, and reduce the palette to the number of colors
  * available.
  */
-PNG_EXPORT(49, void, png_set_quantize,
-    (png_structp png_ptr, png_colorp palette,
-    int num_palette, int maximum_colors, png_const_uint_16p histogram,
-    int full_quantize));
+PNG_EXPORT(49, void, png_set_quantize, (png_structrp png_ptr,
+    png_colorp palette, int num_palette, int maximum_colors,
+    png_const_uint_16p histogram, int full_quantize));
 #endif
 
 #ifdef PNG_READ_GAMMA_SUPPORTED
@@ -1498,71 +1489,69 @@ PNG_EXPORT(49, void, png_set_quantize,
  * API (floating point or fixed.)  Notice, however, that the 'file_gamma' value
  * is the inverse of a 'screen gamma' value.
  */
-PNG_FP_EXPORT(50, void, png_set_gamma,
-    (png_structp png_ptr, double screen_gamma,
-    double override_file_gamma));
-PNG_FIXED_EXPORT(208, void, png_set_gamma_fixed, (png_structp png_ptr,
-    png_fixed_point screen_gamma, png_fixed_point override_file_gamma));
+PNG_FP_EXPORT(50, void, png_set_gamma, (png_structrp png_ptr,
+    double screen_gamma, double override_file_gamma))
+PNG_FIXED_EXPORT(208, void, png_set_gamma_fixed, (png_structrp png_ptr,
+    png_fixed_point screen_gamma, png_fixed_point override_file_gamma))
 #endif
 
 #ifdef PNG_WRITE_FLUSH_SUPPORTED
 /* Set how many lines between output flushes - 0 for no flushing */
-PNG_EXPORT(51, void, png_set_flush, (png_structp png_ptr, int nrows));
+PNG_EXPORT(51, void, png_set_flush, (png_structrp png_ptr, int nrows));
 /* Flush the current PNG output buffer */
-PNG_EXPORT(52, void, png_write_flush, (png_structp png_ptr));
+PNG_EXPORT(52, void, png_write_flush, (png_structrp png_ptr));
 #endif
 
 /* Optional update palette with requested transformations */
-PNG_EXPORT(53, void, png_start_read_image, (png_structp png_ptr));
+PNG_EXPORT(53, void, png_start_read_image, (png_structrp png_ptr));
 
 /* Optional call to update the users info structure */
-PNG_EXPORT(54, void, png_read_update_info,
-    (png_structp png_ptr, png_infop info_ptr));
+PNG_EXPORT(54, void, png_read_update_info, (png_structrp png_ptr,
+    png_inforp info_ptr));
 
 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 /* Read one or more rows of image data. */
-PNG_EXPORT(55, void, png_read_rows, (png_structp png_ptr, png_bytepp row,
+PNG_EXPORT(55, void, png_read_rows, (png_structrp png_ptr, png_bytepp row,
     png_bytepp display_row, png_uint_32 num_rows));
 #endif
 
 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 /* Read a row of data. */
-PNG_EXPORT(56, void, png_read_row, (png_structp png_ptr, png_bytep row,
+PNG_EXPORT(56, void, png_read_row, (png_structrp png_ptr, png_bytep row,
     png_bytep display_row));
 #endif
 
 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 /* Read the whole image into memory at once. */
-PNG_EXPORT(57, void, png_read_image, (png_structp png_ptr, png_bytepp image));
+PNG_EXPORT(57, void, png_read_image, (png_structrp png_ptr, png_bytepp image));
 #endif
 
 /* Write a row of image data */
-PNG_EXPORT(58, void, png_write_row,
-    (png_structp png_ptr, png_const_bytep row));
+PNG_EXPORT(58, void, png_write_row, (png_structrp png_ptr,
+    png_const_bytep row));
 
 /* Write a few rows of image data: (*row) is not written; however, the type
  * is declared as writeable to maintain compatibility with previous versions
  * of libpng and to allow the 'display_row' array from read_rows to be passed
  * unchanged to write_rows.
  */
-PNG_EXPORT(59, void, png_write_rows, (png_structp png_ptr, png_bytepp row,
+PNG_EXPORT(59, void, png_write_rows, (png_structrp png_ptr, png_bytepp row,
     png_uint_32 num_rows));
 
 /* Write the image data */
-PNG_EXPORT(60, void, png_write_image,
-    (png_structp png_ptr, png_bytepp image));
+PNG_EXPORT(60, void, png_write_image, (png_structrp png_ptr, png_bytepp image));
 
 /* Write the end of the PNG file. */
-PNG_EXPORT(61, void, png_write_end,
-    (png_structp png_ptr, png_infop info_ptr));
+PNG_EXPORT(61, void, png_write_end, (png_structrp png_ptr,
+    png_inforp info_ptr));
 
 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 /* Read the end of the PNG file. */
-PNG_EXPORT(62, void, png_read_end, (png_structp png_ptr, png_infop info_ptr));
+PNG_EXPORT(62, void, png_read_end, (png_structrp png_ptr, png_inforp info_ptr));
 #endif
 
 /* Free any memory associated with the png_info_struct */
-PNG_EXPORT(63, void, png_destroy_info_struct, (png_structp png_ptr,
+PNG_EXPORT(63, void, png_destroy_info_struct, (png_const_structrp png_ptr,
     png_infopp info_ptr_ptr));
 
 /* Free any memory associated with the png_struct and the png_info_structs */
@@ -1574,8 +1563,8 @@ PNG_EXPORT(65, void, png_destroy_write_struct, (png_structpp png_ptr_ptr,
     png_infopp info_ptr_ptr));
 
 /* Set the libpng method of handling chunk CRC errors */
-PNG_EXPORT(66, void, png_set_crc_action,
-    (png_structp png_ptr, int crit_action, int ancil_action));
+PNG_EXPORT(66, void, png_set_crc_action, (png_structrp png_ptr, int crit_action,
+    int ancil_action));
 
 /* Values for png_set_crc_action() say how to handle CRC errors in
  * ancillary and critical chunks, and whether to use the data contained
@@ -1593,6 +1582,7 @@ PNG_EXPORT(66, void, png_set_crc_action,
 #define PNG_CRC_QUIET_USE     4  /* quiet/use data      quiet/use data    */
 #define PNG_CRC_NO_CHANGE     5  /* use current value   use current value */
 
+#ifdef PNG_WRITE_SUPPORTED
 /* These functions give the user control over the scan-line filtering in
  * libpng and the compression methods used by zlib.  These functions are
  * mainly useful for testing, as the defaults should work with most users.
@@ -1604,8 +1594,9 @@ PNG_EXPORT(66, void, png_set_crc_action,
 /* Set the filtering method(s) used by libpng.  Currently, the only valid
  * value for "method" is 0.
  */
-PNG_EXPORT(67, void, png_set_filter,
-    (png_structp png_ptr, int method, int filters));
+PNG_EXPORT(67, void, png_set_filter, (png_structrp png_ptr, int method,
+    int filters));
+#endif /* WRITE */
 
 /* Flags for png_set_filter() to say which filters to use.  The flags
  * are chosen so that they don't conflict with real filter types
@@ -1631,6 +1622,7 @@ PNG_EXPORT(67, void, png_set_filter,
 #define PNG_FILTER_VALUE_PAETH 4
 #define PNG_FILTER_VALUE_LAST  5
 
+#ifdef PNG_WRITE_SUPPORTED
 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED /* EXPERIMENTAL */
 /* The "heuristic_method" is given by one of the PNG_FILTER_HEURISTIC_
  * defines, either the default (minimum-sum-of-absolute-differences), or
@@ -1660,14 +1652,14 @@ PNG_EXPORT(67, void, png_set_filter,
  * the weights and costs are set to 1.0, this degenerates the WEIGHTED method
  * to the UNWEIGHTED method, but with added encoding time/computation.
  */
-PNG_FP_EXPORT(68, void, png_set_filter_heuristics, (png_structp png_ptr,
+PNG_FP_EXPORT(68, void, png_set_filter_heuristics, (png_structrp png_ptr,
     int heuristic_method, int num_weights, png_const_doublep filter_weights,
-    png_const_doublep filter_costs));
+    png_const_doublep filter_costs))
 PNG_FIXED_EXPORT(209, void, png_set_filter_heuristics_fixed,
-    (png_structp png_ptr,
-    int heuristic_method, int num_weights, png_const_fixed_point_p
-    filter_weights, png_const_fixed_point_p filter_costs));
-#endif /*  PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */
+    (png_structrp png_ptr, int heuristic_method, int num_weights,
+    png_const_fixed_point_p filter_weights,
+    png_const_fixed_point_p filter_costs))
+#endif /* WRITE_WEIGHTED_FILTER */
 
 /* Heuristic used for row filter selection.  These defines should NOT be
  * changed.
@@ -1677,7 +1669,6 @@ PNG_FIXED_EXPORT(209, void, png_set_filter_heuristics_fixed,
 #define PNG_FILTER_HEURISTIC_WEIGHTED   2  /* Experimental feature */
 #define PNG_FILTER_HEURISTIC_LAST       3  /* Not a valid value */
 
-#ifdef PNG_WRITE_SUPPORTED
 /* Set the library compression level.  Currently, valid values range from
  * 0 - 9, corresponding directly to the zlib compression levels 0 - 9
  * (0 - no compression, 9 - "maximal" compression).  Note that tests have
@@ -1685,45 +1676,47 @@ PNG_FIXED_EXPORT(209, void, png_set_filter_heuristics_fixed,
  * for PNG images, and do considerably fewer caclulations.  In the future,
  * these values may not correspond directly to the zlib compression levels.
  */
-PNG_EXPORT(69, void, png_set_compression_level,
-    (png_structp png_ptr, int level));
+#ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED
+PNG_EXPORT(69, void, png_set_compression_level, (png_structrp png_ptr,
+    int level));
 
-PNG_EXPORT(70, void, png_set_compression_mem_level, (png_structp png_ptr,
+PNG_EXPORT(70, void, png_set_compression_mem_level, (png_structrp png_ptr,
     int mem_level));
 
-PNG_EXPORT(71, void, png_set_compression_strategy, (png_structp png_ptr,
+PNG_EXPORT(71, void, png_set_compression_strategy, (png_structrp png_ptr,
     int strategy));
 
 /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
  * smaller value of window_bits if it can do so safely.
  */
-PNG_EXPORT(72, void, png_set_compression_window_bits, (png_structp png_ptr,
+PNG_EXPORT(72, void, png_set_compression_window_bits, (png_structrp png_ptr,
     int window_bits));
 
-PNG_EXPORT(73, void, png_set_compression_method, (png_structp png_ptr,
+PNG_EXPORT(73, void, png_set_compression_method, (png_structrp png_ptr,
     int method));
-#endif
+#endif /* WRITE_CUSTOMIZE_COMPRESSION */
 
 #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
 /* Also set zlib parameters for compressing non-IDAT chunks */
-PNG_EXPORT(222, void, png_set_text_compression_level,
-    (png_structp png_ptr, int level));
+PNG_EXPORT(222, void, png_set_text_compression_level, (png_structrp png_ptr,
+    int level));
 
-PNG_EXPORT(223, void, png_set_text_compression_mem_level, (png_structp png_ptr,
+PNG_EXPORT(223, void, png_set_text_compression_mem_level, (png_structrp png_ptr,
     int mem_level));
 
-PNG_EXPORT(224, void, png_set_text_compression_strategy, (png_structp png_ptr,
+PNG_EXPORT(224, void, png_set_text_compression_strategy, (png_structrp png_ptr,
     int strategy));
 
 /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
  * smaller value of window_bits if it can do so safely.
  */
-PNG_EXPORT(225, void, png_set_text_compression_window_bits, (png_structp
-    png_ptr, int window_bits));
+PNG_EXPORT(225, void, png_set_text_compression_window_bits,
+    (png_structrp png_ptr, int window_bits));
 
-PNG_EXPORT(226, void, png_set_text_compression_method, (png_structp png_ptr,
+PNG_EXPORT(226, void, png_set_text_compression_method, (png_structrp png_ptr,
     int method));
-#endif /* PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED */
+#endif /* WRITE_CUSTOMIZE_ZTXT_COMPRESSION */
+#endif /* WRITE */
 
 /* These next functions are called for input/output, memory, and error
  * handling.  They are in the file pngrio.c, pngwio.c, and pngerror.c,
@@ -1736,7 +1729,7 @@ PNG_EXPORT(226, void, png_set_text_compression_method, (png_structp png_ptr,
 
 #ifdef PNG_STDIO_SUPPORTED
 /* Initialize the input/output for the PNG file to the default functions. */
-PNG_EXPORT(74, void, png_init_io, (png_structp png_ptr, png_FILE_p fp));
+PNG_EXPORT(74, void, png_init_io, (png_structrp png_ptr, png_FILE_p fp));
 #endif
 
 /* Replace the (error and abort), and warning functions with user
@@ -1747,12 +1740,11 @@ PNG_EXPORT(74, void, png_init_io, (png_structp png_ptr, png_FILE_p fp));
  * default function will be used.
  */
 
-PNG_EXPORT(75, void, png_set_error_fn,
-    (png_structp png_ptr, png_voidp error_ptr,
-    png_error_ptr error_fn, png_error_ptr warning_fn));
+PNG_EXPORT(75, void, png_set_error_fn, (png_structrp png_ptr,
+    png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warning_fn));
 
 /* Return the user pointer associated with the error functions */
-PNG_EXPORT(76, png_voidp, png_get_error_ptr, (png_const_structp png_ptr));
+PNG_EXPORT(76, png_voidp, png_get_error_ptr, (png_const_structrp png_ptr));
 
 /* Replace the default data output functions with a user supplied one(s).
  * If buffered output is not used, then output_flush_fn can be set to NULL.
@@ -1764,47 +1756,47 @@ PNG_EXPORT(76, png_voidp, png_get_error_ptr, (png_const_structp png_ptr));
  * default flush function, which uses the standard *FILE structure, will
  * be used.
  */
-PNG_EXPORT(77, void, png_set_write_fn, (png_structp png_ptr, png_voidp io_ptr,
+PNG_EXPORT(77, void, png_set_write_fn, (png_structrp png_ptr, png_voidp io_ptr,
     png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn));
 
 /* Replace the default data input function with a user supplied one. */
-PNG_EXPORT(78, void, png_set_read_fn, (png_structp png_ptr, png_voidp io_ptr,
+PNG_EXPORT(78, void, png_set_read_fn, (png_structrp png_ptr, png_voidp io_ptr,
     png_rw_ptr read_data_fn));
 
 /* Return the user pointer associated with the I/O functions */
-PNG_EXPORT(79, png_voidp, png_get_io_ptr, (png_structp png_ptr));
+PNG_EXPORT(79, png_voidp, png_get_io_ptr, (png_const_structrp png_ptr));
 
-PNG_EXPORT(80, void, png_set_read_status_fn, (png_structp png_ptr,
+PNG_EXPORT(80, void, png_set_read_status_fn, (png_structrp png_ptr,
     png_read_status_ptr read_row_fn));
 
-PNG_EXPORT(81, void, png_set_write_status_fn, (png_structp png_ptr,
+PNG_EXPORT(81, void, png_set_write_status_fn, (png_structrp png_ptr,
     png_write_status_ptr write_row_fn));
 
 #ifdef PNG_USER_MEM_SUPPORTED
 /* Replace the default memory allocation functions with user supplied one(s). */
-PNG_EXPORT(82, void, png_set_mem_fn, (png_structp png_ptr, png_voidp mem_ptr,
+PNG_EXPORT(82, void, png_set_mem_fn, (png_structrp png_ptr, png_voidp mem_ptr,
     png_malloc_ptr malloc_fn, png_free_ptr free_fn));
 /* Return the user pointer associated with the memory functions */
-PNG_EXPORT(83, png_voidp, png_get_mem_ptr, (png_const_structp png_ptr));
+PNG_EXPORT(83, png_voidp, png_get_mem_ptr, (png_const_structrp png_ptr));
 #endif
 
 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
-PNG_EXPORT(84, void, png_set_read_user_transform_fn, (png_structp png_ptr,
+PNG_EXPORT(84, void, png_set_read_user_transform_fn, (png_structrp png_ptr,
     png_user_transform_ptr read_user_transform_fn));
 #endif
 
 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
-PNG_EXPORT(85, void, png_set_write_user_transform_fn, (png_structp png_ptr,
+PNG_EXPORT(85, void, png_set_write_user_transform_fn, (png_structrp png_ptr,
     png_user_transform_ptr write_user_transform_fn));
 #endif
 
 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
-PNG_EXPORT(86, void, png_set_user_transform_info, (png_structp png_ptr,
+PNG_EXPORT(86, void, png_set_user_transform_info, (png_structrp png_ptr,
     png_voidp user_transform_ptr, int user_transform_depth,
     int user_transform_channels));
 /* Return the user pointer associated with the user transform functions */
 PNG_EXPORT(87, png_voidp, png_get_user_transform_ptr,
-    (png_const_structp png_ptr));
+    (png_const_structrp png_ptr));
 #endif
 
 #ifdef PNG_USER_TRANSFORM_INFO_SUPPORTED
@@ -1819,31 +1811,53 @@ PNG_EXPORT(87, png_voidp, png_get_user_transform_ptr,
  * find the output pixel (x,y) given an interlaced sub-image pixel
  * (row,col,pass).  (See below for these macros.)
  */
-PNG_EXPORT(217, png_uint_32, png_get_current_row_number, (png_const_structp));
-PNG_EXPORT(218, png_byte, png_get_current_pass_number, (png_const_structp));
+PNG_EXPORT(217, png_uint_32, png_get_current_row_number, (png_const_structrp));
+PNG_EXPORT(218, png_byte, png_get_current_pass_number, (png_const_structrp));
 #endif
 
-#ifdef PNG_USER_CHUNKS_SUPPORTED
-PNG_EXPORT(88, void, png_set_read_user_chunk_fn, (png_structp png_ptr,
+#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
+/* This callback is called only for *unknown* chunks.  If
+ * PNG_HANDLE_AS_UNKNOWN_SUPPORTED is set then it is possible to set known
+ * chunks to be treated as unknown, however in this case the callback must do
+ * any processing required by the chunk (e.g. by calling the appropriate
+ * png_set_ APIs.)
+ *
+ * There is no write support - on write, by default, all the chunks in the
+ * 'unknown' list are written in the specified position.
+ *
+ * The integer return from the callback function is interpreted thus:
+ *
+ * negative: An error occurred; png_chunk_error will be called.
+ *     zero: The chunk was not handled, the chunk will be saved. A critical
+ *           chunk will cause an error at this point unless it is to be saved.
+ * positive: The chunk was handled, libpng will ignore/discard it.
+ *
+ * See "INTERACTION WTIH USER CHUNK CALLBACKS" below for important notes about
+ * how this behavior will change in libpng 1.7
+ */
+PNG_EXPORT(88, void, png_set_read_user_chunk_fn, (png_structrp png_ptr,
     png_voidp user_chunk_ptr, png_user_chunk_ptr read_user_chunk_fn));
-PNG_EXPORT(89, png_voidp, png_get_user_chunk_ptr, (png_const_structp png_ptr));
+#endif
+
+#ifdef PNG_USER_CHUNKS_SUPPORTED
+PNG_EXPORT(89, png_voidp, png_get_user_chunk_ptr, (png_const_structrp png_ptr));
 #endif
 
 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
 /* Sets the function callbacks for the push reader, and a pointer to a
  * user-defined structure available to the callback functions.
  */
-PNG_EXPORT(90, void, png_set_progressive_read_fn, (png_structp png_ptr,
+PNG_EXPORT(90, void, png_set_progressive_read_fn, (png_structrp png_ptr,
     png_voidp progressive_ptr, png_progressive_info_ptr info_fn,
     png_progressive_row_ptr row_fn, png_progressive_end_ptr end_fn));
 
 /* Returns the user pointer associated with the push read functions */
-PNG_EXPORT(91, png_voidp, png_get_progressive_ptr, (png_const_structp png_ptr));
+PNG_EXPORT(91, png_voidp, png_get_progressive_ptr,
+    (png_const_structrp png_ptr));
 
 /* Function to be called when data becomes available */
-PNG_EXPORT(92, void, png_process_data,
-    (png_structp png_ptr, png_infop info_ptr,
-    png_bytep buffer, png_size_t buffer_size));
+PNG_EXPORT(92, void, png_process_data, (png_structrp png_ptr,
+    png_inforp info_ptr, png_bytep buffer, png_size_t buffer_size));
 
 /* A function which may be called *only* within png_process_data to stop the
  * processing of any more data.  The function returns the number of bytes
@@ -1852,7 +1866,7 @@ PNG_EXPORT(92, void, png_process_data,
  * 'save' is set to true the routine will first save all the pending data and
  * will always return 0.
  */
-PNG_EXPORT(219, png_size_t, png_process_data_pause, (png_structp, int save));
+PNG_EXPORT(219, png_size_t, png_process_data_pause, (png_structrp, int save));
 
 /* A function which may be called *only* outside (after) a call to
  * png_process_data.  It returns the number of bytes of data to skip in the
@@ -1860,42 +1874,43 @@ PNG_EXPORT(219, png_size_t, png_process_data_pause, (png_structp, int save));
  * application must skip than number of bytes of input data and pass the
  * following data to the next call to png_process_data.
  */
-PNG_EXPORT(220, png_uint_32, png_process_data_skip, (png_structp));
+PNG_EXPORT(220, png_uint_32, png_process_data_skip, (png_structrp));
 
-#ifdef PNG_READ_INTERLACING_SUPPORTED
 /* Function that combines rows.  'new_row' is a flag that should come from
  * the callback and be non-NULL if anything needs to be done; the library
  * stores its own version of the new data internally and ignores the passed
  * in value.
  */
-PNG_EXPORT(93, void, png_progressive_combine_row, (png_structp png_ptr,
+PNG_EXPORT(93, void, png_progressive_combine_row, (png_const_structrp png_ptr,
     png_bytep old_row, png_const_bytep new_row));
-#endif /* PNG_READ_INTERLACING_SUPPORTED */
-#endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
+#endif /* PROGRESSIVE_READ */
 
-PNG_EXPORTA(94, png_voidp, png_malloc,
-    (png_structp png_ptr, png_alloc_size_t size),
-    PNG_ALLOCATED);
+PNG_EXPORTA(94, png_voidp, png_malloc, (png_const_structrp png_ptr,
+    png_alloc_size_t size), PNG_ALLOCATED);
 /* Added at libpng version 1.4.0 */
-PNG_EXPORTA(95, png_voidp, png_calloc,
-    (png_structp png_ptr, png_alloc_size_t size),
-    PNG_ALLOCATED);
+PNG_EXPORTA(95, png_voidp, png_calloc, (png_const_structrp png_ptr,
+    png_alloc_size_t size), PNG_ALLOCATED);
 
 /* Added at libpng version 1.2.4 */
-PNG_EXPORTA(96, png_voidp, png_malloc_warn, (png_structp png_ptr,
+PNG_EXPORTA(96, png_voidp, png_malloc_warn, (png_const_structrp png_ptr,
     png_alloc_size_t size), PNG_ALLOCATED);
 
 /* Frees a pointer allocated by png_malloc() */
-PNG_EXPORT(97, void, png_free, (png_structp png_ptr, png_voidp ptr));
+PNG_EXPORT(97, void, png_free, (png_const_structrp png_ptr, png_voidp ptr));
 
 /* Free data that was allocated internally */
-PNG_EXPORT(98, void, png_free_data,
-    (png_structp png_ptr, png_infop info_ptr, png_uint_32 free_me, int num));
+PNG_EXPORT(98, void, png_free_data, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 free_me, int num));
 
 /* Reassign responsibility for freeing existing data, whether allocated
- * by libpng or by the application */
-PNG_EXPORT(99, void, png_data_freer,
-    (png_structp png_ptr, png_infop info_ptr, int freer, png_uint_32 mask));
+ * by libpng or by the application; this works on the png_info structure passed
+ * in, it does not change the state for other png_info structures.
+ *
+ * It is unlikely that this function works correctly as of 1.6.0 and using it
+ * may result either in memory leaks or double free of allocated data.
+ */
+PNG_EXPORT(99, void, png_data_freer, (png_const_structrp png_ptr,
+    png_inforp info_ptr, int freer, png_uint_32 mask));
 
 /* Assignments for png_data_freer */
 #define PNG_DESTROY_WILL_FREE_DATA 1
@@ -1908,8 +1923,10 @@ PNG_EXPORT(99, void, png_data_freer,
 #define PNG_FREE_ROWS 0x0040
 #define PNG_FREE_PCAL 0x0080
 #define PNG_FREE_SCAL 0x0100
-#define PNG_FREE_UNKN 0x0200
-#define PNG_FREE_LIST 0x0400
+#ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
+#  define PNG_FREE_UNKN 0x0200
+#endif
+/*      PNG_FREE_LIST 0x0400    removed in 1.6.0 because it is ignored */
 #define PNG_FREE_PLTE 0x1000
 #define PNG_FREE_TRNS 0x2000
 #define PNG_FREE_TEXT 0x4000
@@ -1917,50 +1934,55 @@ PNG_EXPORT(99, void, png_data_freer,
 #define PNG_FREE_MUL  0x4220 /* PNG_FREE_SPLT|PNG_FREE_TEXT|PNG_FREE_UNKN */
 
 #ifdef PNG_USER_MEM_SUPPORTED
-PNG_EXPORTA(100, png_voidp, png_malloc_default, (png_structp png_ptr,
-    png_alloc_size_t size), PNG_ALLOCATED);
-PNG_EXPORT(101, void, png_free_default, (png_structp png_ptr, png_voidp ptr));
+PNG_EXPORTA(100, png_voidp, png_malloc_default, (png_const_structrp png_ptr,
+    png_alloc_size_t size), PNG_ALLOCATED PNG_DEPRECATED);
+PNG_EXPORTA(101, void, png_free_default, (png_const_structrp png_ptr,
+    png_voidp ptr), PNG_DEPRECATED);
 #endif
 
 #ifdef PNG_ERROR_TEXT_SUPPORTED
 /* Fatal error in PNG image of libpng - can't continue */
-PNG_EXPORTA(102, void, png_error,
-    (png_structp png_ptr, png_const_charp error_message),
-    PNG_NORETURN);
+PNG_EXPORTA(102, void, png_error, (png_const_structrp png_ptr,
+    png_const_charp error_message), PNG_NORETURN);
 
 /* The same, but the chunk name is prepended to the error string. */
-PNG_EXPORTA(103, void, png_chunk_error, (png_structp png_ptr,
+PNG_EXPORTA(103, void, png_chunk_error, (png_const_structrp png_ptr,
     png_const_charp error_message), PNG_NORETURN);
 
 #else
 /* Fatal error in PNG image of libpng - can't continue */
-PNG_EXPORTA(104, void, png_err, (png_structp png_ptr), PNG_NORETURN);
+PNG_EXPORTA(104, void, png_err, (png_const_structrp png_ptr), PNG_NORETURN);
+#  define png_error(s1,s2) png_err(s1)
+#  define png_chunk_error(s1,s2) png_err(s1)
 #endif
 
 #ifdef PNG_WARNINGS_SUPPORTED
 /* Non-fatal error in libpng.  Can continue, but may have a problem. */
-PNG_EXPORT(105, void, png_warning, (png_structp png_ptr,
+PNG_EXPORT(105, void, png_warning, (png_const_structrp png_ptr,
     png_const_charp warning_message));
 
 /* Non-fatal error in libpng, chunk name is prepended to message. */
-PNG_EXPORT(106, void, png_chunk_warning, (png_structp png_ptr,
+PNG_EXPORT(106, void, png_chunk_warning, (png_const_structrp png_ptr,
     png_const_charp warning_message));
+#else
+#  define png_warning(s1,s2) ((void)(s1))
+#  define png_chunk_warning(s1,s2) ((void)(s1))
 #endif
 
 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
 /* Benign error in libpng.  Can continue, but may have a problem.
  * User can choose whether to handle as a fatal error or as a warning. */
-#  undef png_benign_error
-PNG_EXPORT(107, void, png_benign_error, (png_structp png_ptr,
+PNG_EXPORT(107, void, png_benign_error, (png_const_structrp png_ptr,
     png_const_charp warning_message));
 
-/* Same, chunk name is prepended to message. */
-#  undef png_chunk_benign_error
-PNG_EXPORT(108, void, png_chunk_benign_error, (png_structp png_ptr,
+#ifdef PNG_READ_SUPPORTED
+/* Same, chunk name is prepended to message (only during read) */
+PNG_EXPORT(108, void, png_chunk_benign_error, (png_const_structrp png_ptr,
     png_const_charp warning_message));
+#endif
 
 PNG_EXPORT(109, void, png_set_benign_errors,
-    (png_structp png_ptr, int allowed));
+    (png_structrp png_ptr, int allowed));
 #else
 #  ifdef PNG_ALLOW_BENIGN_ERRORS
 #    define png_benign_error png_warning
@@ -1984,289 +2006,274 @@ PNG_EXPORT(109, void, png_set_benign_errors,
  * png_info_struct.
  */
 /* Returns "flag" if chunk data is valid in info_ptr. */
-PNG_EXPORT(110, png_uint_32, png_get_valid,
-    (png_const_structp png_ptr, png_const_infop info_ptr,
-    png_uint_32 flag));
+PNG_EXPORT(110, png_uint_32, png_get_valid, (png_const_structrp png_ptr,
+    png_const_inforp info_ptr, png_uint_32 flag));
 
 /* Returns number of bytes needed to hold a transformed row. */
-PNG_EXPORT(111, png_size_t, png_get_rowbytes, (png_const_structp png_ptr,
-    png_const_infop info_ptr));
+PNG_EXPORT(111, png_size_t, png_get_rowbytes, (png_const_structrp png_ptr,
+    png_const_inforp info_ptr));
 
 #ifdef PNG_INFO_IMAGE_SUPPORTED
 /* Returns row_pointers, which is an array of pointers to scanlines that was
  * returned from png_read_png().
  */
-PNG_EXPORT(112, png_bytepp, png_get_rows,
-    (png_const_structp png_ptr, png_const_infop info_ptr));
+PNG_EXPORT(112, png_bytepp, png_get_rows, (png_const_structrp png_ptr,
+    png_const_inforp info_ptr));
+
 /* Set row_pointers, which is an array of pointers to scanlines for use
  * by png_write_png().
  */
-PNG_EXPORT(113, void, png_set_rows, (png_structp png_ptr,
-    png_infop info_ptr, png_bytepp row_pointers));
+PNG_EXPORT(113, void, png_set_rows, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_bytepp row_pointers));
 #endif
 
 /* Returns number of color channels in image. */
-PNG_EXPORT(114, png_byte, png_get_channels,
-    (png_const_structp png_ptr, png_const_infop info_ptr));
+PNG_EXPORT(114, png_byte, png_get_channels, (png_const_structrp png_ptr,
+    png_const_inforp info_ptr));
 
 #ifdef PNG_EASY_ACCESS_SUPPORTED
 /* Returns image width in pixels. */
-PNG_EXPORT(115, png_uint_32, png_get_image_width, (png_const_structp png_ptr,
-    png_const_infop info_ptr));
+PNG_EXPORT(115, png_uint_32, png_get_image_width, (png_const_structrp png_ptr,
+    png_const_inforp info_ptr));
 
 /* Returns image height in pixels. */
-PNG_EXPORT(116, png_uint_32, png_get_image_height, (png_const_structp png_ptr,
-    png_const_infop info_ptr));
+PNG_EXPORT(116, png_uint_32, png_get_image_height, (png_const_structrp png_ptr,
+    png_const_inforp info_ptr));
 
 /* Returns image bit_depth. */
-PNG_EXPORT(117, png_byte, png_get_bit_depth,
-    (png_const_structp png_ptr, png_const_infop info_ptr));
+PNG_EXPORT(117, png_byte, png_get_bit_depth, (png_const_structrp png_ptr,
+    png_const_inforp info_ptr));
 
 /* Returns image color_type. */
-PNG_EXPORT(118, png_byte, png_get_color_type, (png_const_structp png_ptr,
-    png_const_infop info_ptr));
+PNG_EXPORT(118, png_byte, png_get_color_type, (png_const_structrp png_ptr,
+    png_const_inforp info_ptr));
 
 /* Returns image filter_type. */
-PNG_EXPORT(119, png_byte, png_get_filter_type, (png_const_structp png_ptr,
-    png_const_infop info_ptr));
+PNG_EXPORT(119, png_byte, png_get_filter_type, (png_const_structrp png_ptr,
+    png_const_inforp info_ptr));
 
 /* Returns image interlace_type. */
-PNG_EXPORT(120, png_byte, png_get_interlace_type, (png_const_structp png_ptr,
-    png_const_infop info_ptr));
+PNG_EXPORT(120, png_byte, png_get_interlace_type, (png_const_structrp png_ptr,
+    png_const_inforp info_ptr));
 
 /* Returns image compression_type. */
-PNG_EXPORT(121, png_byte, png_get_compression_type, (png_const_structp png_ptr,
-    png_const_infop info_ptr));
+PNG_EXPORT(121, png_byte, png_get_compression_type, (png_const_structrp png_ptr,
+    png_const_inforp info_ptr));
 
 /* Returns image resolution in pixels per meter, from pHYs chunk data. */
 PNG_EXPORT(122, png_uint_32, png_get_pixels_per_meter,
-    (png_const_structp png_ptr, png_const_infop info_ptr));
+    (png_const_structrp png_ptr, png_const_inforp info_ptr));
 PNG_EXPORT(123, png_uint_32, png_get_x_pixels_per_meter,
-    (png_const_structp png_ptr, png_const_infop info_ptr));
+    (png_const_structrp png_ptr, png_const_inforp info_ptr));
 PNG_EXPORT(124, png_uint_32, png_get_y_pixels_per_meter,
-    (png_const_structp png_ptr, png_const_infop info_ptr));
+    (png_const_structrp png_ptr, png_const_inforp info_ptr));
 
 /* Returns pixel aspect ratio, computed from pHYs chunk data.  */
 PNG_FP_EXPORT(125, float, png_get_pixel_aspect_ratio,
-    (png_const_structp png_ptr, png_const_infop info_ptr));
+    (png_const_structrp png_ptr, png_const_inforp info_ptr))
 PNG_FIXED_EXPORT(210, png_fixed_point, png_get_pixel_aspect_ratio_fixed,
-    (png_const_structp png_ptr, png_const_infop info_ptr));
+    (png_const_structrp png_ptr, png_const_inforp info_ptr))
 
 /* Returns image x, y offset in pixels or microns, from oFFs chunk data. */
 PNG_EXPORT(126, png_int_32, png_get_x_offset_pixels,
-    (png_const_structp png_ptr, png_const_infop info_ptr));
+    (png_const_structrp png_ptr, png_const_inforp info_ptr));
 PNG_EXPORT(127, png_int_32, png_get_y_offset_pixels,
-    (png_const_structp png_ptr, png_const_infop info_ptr));
+    (png_const_structrp png_ptr, png_const_inforp info_ptr));
 PNG_EXPORT(128, png_int_32, png_get_x_offset_microns,
-    (png_const_structp png_ptr, png_const_infop info_ptr));
+    (png_const_structrp png_ptr, png_const_inforp info_ptr));
 PNG_EXPORT(129, png_int_32, png_get_y_offset_microns,
-    (png_const_structp png_ptr, png_const_infop info_ptr));
+    (png_const_structrp png_ptr, png_const_inforp info_ptr));
 
-#endif /* PNG_EASY_ACCESS_SUPPORTED */
+#endif /* EASY_ACCESS */
 
+#ifdef PNG_READ_SUPPORTED
 /* Returns pointer to signature string read from PNG header */
-PNG_EXPORT(130, png_const_bytep, png_get_signature,
-    (png_const_structp png_ptr, png_infop info_ptr));
+PNG_EXPORT(130, png_const_bytep, png_get_signature, (png_const_structrp png_ptr,
+    png_const_inforp info_ptr));
+#endif
 
 #ifdef PNG_bKGD_SUPPORTED
-PNG_EXPORT(131, png_uint_32, png_get_bKGD,
-    (png_const_structp png_ptr, png_infop info_ptr,
-    png_color_16p *background));
+PNG_EXPORT(131, png_uint_32, png_get_bKGD, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_color_16p *background));
 #endif
 
 #ifdef PNG_bKGD_SUPPORTED
-PNG_EXPORT(132, void, png_set_bKGD, (png_structp png_ptr, png_infop info_ptr,
-    png_const_color_16p background));
+PNG_EXPORT(132, void, png_set_bKGD, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_const_color_16p background));
 #endif
 
 #ifdef PNG_cHRM_SUPPORTED
-PNG_FP_EXPORT(133, png_uint_32, png_get_cHRM, (png_const_structp png_ptr,
-   png_const_infop info_ptr, double *white_x, double *white_y, double *red_x,
+PNG_FP_EXPORT(133, png_uint_32, png_get_cHRM, (png_const_structrp png_ptr,
+    png_const_inforp info_ptr, double *white_x, double *white_y, double *red_x,
     double *red_y, double *green_x, double *green_y, double *blue_x,
-    double *blue_y));
-PNG_FP_EXPORT(230, png_uint_32, png_get_cHRM_XYZ, (png_structp png_ptr,
-    png_const_infop info_ptr, double *red_X, double *red_Y, double *red_Z,
+    double *blue_y))
+PNG_FP_EXPORT(230, png_uint_32, png_get_cHRM_XYZ, (png_const_structrp png_ptr,
+    png_const_inforp info_ptr, double *red_X, double *red_Y, double *red_Z,
     double *green_X, double *green_Y, double *green_Z, double *blue_X,
-    double *blue_Y, double *blue_Z));
-#ifdef PNG_FIXED_POINT_SUPPORTED /* Otherwise not implemented */
+    double *blue_Y, double *blue_Z))
 PNG_FIXED_EXPORT(134, png_uint_32, png_get_cHRM_fixed,
-    (png_const_structp png_ptr,
-    png_const_infop info_ptr, png_fixed_point *int_white_x,
-    png_fixed_point *int_white_y, png_fixed_point *int_red_x,
-    png_fixed_point *int_red_y, png_fixed_point *int_green_x,
-    png_fixed_point *int_green_y, png_fixed_point *int_blue_x,
-    png_fixed_point *int_blue_y));
-#endif
+    (png_const_structrp png_ptr, png_const_inforp info_ptr,
+    png_fixed_point *int_white_x, png_fixed_point *int_white_y,
+    png_fixed_point *int_red_x, png_fixed_point *int_red_y,
+    png_fixed_point *int_green_x, png_fixed_point *int_green_y,
+    png_fixed_point *int_blue_x, png_fixed_point *int_blue_y))
 PNG_FIXED_EXPORT(231, png_uint_32, png_get_cHRM_XYZ_fixed,
-    (png_structp png_ptr, png_const_infop info_ptr,
+    (png_const_structrp png_ptr, png_const_inforp info_ptr,
     png_fixed_point *int_red_X, png_fixed_point *int_red_Y,
     png_fixed_point *int_red_Z, png_fixed_point *int_green_X,
     png_fixed_point *int_green_Y, png_fixed_point *int_green_Z,
     png_fixed_point *int_blue_X, png_fixed_point *int_blue_Y,
-    png_fixed_point *int_blue_Z));
+    png_fixed_point *int_blue_Z))
 #endif
 
 #ifdef PNG_cHRM_SUPPORTED
-PNG_FP_EXPORT(135, void, png_set_cHRM,
-    (png_structp png_ptr, png_infop info_ptr,
+PNG_FP_EXPORT(135, void, png_set_cHRM, (png_const_structrp png_ptr,
+    png_inforp info_ptr,
     double white_x, double white_y, double red_x, double red_y, double green_x,
-    double green_y, double blue_x, double blue_y));
-PNG_FP_EXPORT(232, void, png_set_cHRM_XYZ, (png_structp png_ptr,
-    png_infop info_ptr, double red_X, double red_Y, double red_Z,
+    double green_y, double blue_x, double blue_y))
+PNG_FP_EXPORT(232, void, png_set_cHRM_XYZ, (png_const_structrp png_ptr,
+    png_inforp info_ptr, double red_X, double red_Y, double red_Z,
     double green_X, double green_Y, double green_Z, double blue_X,
-    double blue_Y, double blue_Z));
-PNG_FIXED_EXPORT(136, void, png_set_cHRM_fixed, (png_structp png_ptr,
-    png_infop info_ptr, png_fixed_point int_white_x,
+    double blue_Y, double blue_Z))
+PNG_FIXED_EXPORT(136, void, png_set_cHRM_fixed, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_fixed_point int_white_x,
     png_fixed_point int_white_y, png_fixed_point int_red_x,
     png_fixed_point int_red_y, png_fixed_point int_green_x,
     png_fixed_point int_green_y, png_fixed_point int_blue_x,
-    png_fixed_point int_blue_y));
-PNG_FIXED_EXPORT(233, void, png_set_cHRM_XYZ_fixed, (png_structp png_ptr,
-    png_infop info_ptr, png_fixed_point int_red_X, png_fixed_point int_red_Y,
+    png_fixed_point int_blue_y))
+PNG_FIXED_EXPORT(233, void, png_set_cHRM_XYZ_fixed, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_fixed_point int_red_X, png_fixed_point int_red_Y,
     png_fixed_point int_red_Z, png_fixed_point int_green_X,
     png_fixed_point int_green_Y, png_fixed_point int_green_Z,
     png_fixed_point int_blue_X, png_fixed_point int_blue_Y,
-    png_fixed_point int_blue_Z));
+    png_fixed_point int_blue_Z))
 #endif
 
 #ifdef PNG_gAMA_SUPPORTED
-PNG_FP_EXPORT(137, png_uint_32, png_get_gAMA,
-    (png_const_structp png_ptr, png_const_infop info_ptr,
-    double *file_gamma));
+PNG_FP_EXPORT(137, png_uint_32, png_get_gAMA, (png_const_structrp png_ptr,
+    png_const_inforp info_ptr, double *file_gamma))
 PNG_FIXED_EXPORT(138, png_uint_32, png_get_gAMA_fixed,
-    (png_const_structp png_ptr, png_const_infop info_ptr,
-    png_fixed_point *int_file_gamma));
+    (png_const_structrp png_ptr, png_const_inforp info_ptr,
+    png_fixed_point *int_file_gamma))
 #endif
 
 #ifdef PNG_gAMA_SUPPORTED
-PNG_FP_EXPORT(139, void, png_set_gAMA, (png_structp png_ptr,
-    png_infop info_ptr, double file_gamma));
-PNG_FIXED_EXPORT(140, void, png_set_gAMA_fixed, (png_structp png_ptr,
-    png_infop info_ptr, png_fixed_point int_file_gamma));
+PNG_FP_EXPORT(139, void, png_set_gAMA, (png_const_structrp png_ptr,
+    png_inforp info_ptr, double file_gamma))
+PNG_FIXED_EXPORT(140, void, png_set_gAMA_fixed, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_fixed_point int_file_gamma))
 #endif
 
 #ifdef PNG_hIST_SUPPORTED
-PNG_EXPORT(141, png_uint_32, png_get_hIST,
-    (png_const_structp png_ptr, png_const_infop info_ptr,
-    png_uint_16p *hist));
+PNG_EXPORT(141, png_uint_32, png_get_hIST, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_uint_16p *hist));
 #endif
 
 #ifdef PNG_hIST_SUPPORTED
-PNG_EXPORT(142, void, png_set_hIST, (png_structp png_ptr,
-    png_infop info_ptr, png_const_uint_16p hist));
+PNG_EXPORT(142, void, png_set_hIST, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_const_uint_16p hist));
 #endif
 
-PNG_EXPORT(143, png_uint_32, png_get_IHDR,
-    (png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 *width, png_uint_32 *height, int *bit_depth, int *color_type,
-    int *interlace_method, int *compression_method, int *filter_method));
+PNG_EXPORT(143, png_uint_32, png_get_IHDR, (png_const_structrp png_ptr,
+    png_const_inforp info_ptr, png_uint_32 *width, png_uint_32 *height,
+    int *bit_depth, int *color_type, int *interlace_method,
+    int *compression_method, int *filter_method));
 
-PNG_EXPORT(144, void, png_set_IHDR,
-    (png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 width, png_uint_32 height, int bit_depth, int color_type,
-    int interlace_method, int compression_method, int filter_method));
+PNG_EXPORT(144, void, png_set_IHDR, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 width, png_uint_32 height, int bit_depth,
+    int color_type, int interlace_method, int compression_method,
+    int filter_method));
 
 #ifdef PNG_oFFs_SUPPORTED
-PNG_EXPORT(145, png_uint_32, png_get_oFFs,
-    (png_const_structp png_ptr, png_const_infop info_ptr,
-    png_int_32 *offset_x, png_int_32 *offset_y, int *unit_type));
+PNG_EXPORT(145, png_uint_32, png_get_oFFs, (png_const_structrp png_ptr,
+   png_const_inforp info_ptr, png_int_32 *offset_x, png_int_32 *offset_y,
+   int *unit_type));
 #endif
 
 #ifdef PNG_oFFs_SUPPORTED
-PNG_EXPORT(146, void, png_set_oFFs,
-    (png_structp png_ptr, png_infop info_ptr,
-    png_int_32 offset_x, png_int_32 offset_y, int unit_type));
+PNG_EXPORT(146, void, png_set_oFFs, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_int_32 offset_x, png_int_32 offset_y,
+    int unit_type));
 #endif
 
 #ifdef PNG_pCAL_SUPPORTED
-PNG_EXPORT(147, png_uint_32, png_get_pCAL,
-    (png_const_structp png_ptr, png_const_infop info_ptr,
-    png_charp *purpose, png_int_32 *X0, png_int_32 *X1, int *type,
-    int *nparams,
-    png_charp *units, png_charpp *params));
+PNG_EXPORT(147, png_uint_32, png_get_pCAL, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_charp *purpose, png_int_32 *X0,
+    png_int_32 *X1, int *type, int *nparams, png_charp *units,
+    png_charpp *params));
 #endif
 
 #ifdef PNG_pCAL_SUPPORTED
-PNG_EXPORT(148, void, png_set_pCAL, (png_structp png_ptr,
-    png_infop info_ptr,
-    png_const_charp purpose, png_int_32 X0, png_int_32 X1, int type,
-    int nparams, png_const_charp units, png_charpp params));
+PNG_EXPORT(148, void, png_set_pCAL, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_const_charp purpose, png_int_32 X0, png_int_32 X1,
+    int type, int nparams, png_const_charp units, png_charpp params));
 #endif
 
 #ifdef PNG_pHYs_SUPPORTED
-PNG_EXPORT(149, png_uint_32, png_get_pHYs,
-    (png_const_structp png_ptr, png_const_infop info_ptr,
-    png_uint_32 *res_x, png_uint_32 *res_y, int *unit_type));
+PNG_EXPORT(149, png_uint_32, png_get_pHYs, (png_const_structrp png_ptr,
+    png_const_inforp info_ptr, png_uint_32 *res_x, png_uint_32 *res_y,
+    int *unit_type));
 #endif
 
 #ifdef PNG_pHYs_SUPPORTED
-PNG_EXPORT(150, void, png_set_pHYs,
-    (png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 res_x, png_uint_32 res_y, int unit_type));
+PNG_EXPORT(150, void, png_set_pHYs, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 res_x, png_uint_32 res_y, int unit_type));
 #endif
 
-PNG_EXPORT(151, png_uint_32, png_get_PLTE,
-    (png_const_structp png_ptr, png_const_infop info_ptr,
-    png_colorp *palette, int *num_palette));
+PNG_EXPORT(151, png_uint_32, png_get_PLTE, (png_const_structrp png_ptr,
+   png_inforp info_ptr, png_colorp *palette, int *num_palette));
 
-PNG_EXPORT(152, void, png_set_PLTE,
-    (png_structp png_ptr, png_infop info_ptr,
-    png_const_colorp palette, int num_palette));
+PNG_EXPORT(152, void, png_set_PLTE, (png_structrp png_ptr,
+    png_inforp info_ptr, png_const_colorp palette, int num_palette));
 
 #ifdef PNG_sBIT_SUPPORTED
-PNG_EXPORT(153, png_uint_32, png_get_sBIT,
-    (png_const_structp png_ptr, png_infop info_ptr,
-    png_color_8p *sig_bit));
+PNG_EXPORT(153, png_uint_32, png_get_sBIT, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_color_8p *sig_bit));
 #endif
 
 #ifdef PNG_sBIT_SUPPORTED
-PNG_EXPORT(154, void, png_set_sBIT,
-    (png_structp png_ptr, png_infop info_ptr, png_const_color_8p sig_bit));
+PNG_EXPORT(154, void, png_set_sBIT, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_const_color_8p sig_bit));
 #endif
 
 #ifdef PNG_sRGB_SUPPORTED
-PNG_EXPORT(155, png_uint_32, png_get_sRGB, (png_const_structp png_ptr,
-    png_const_infop info_ptr, int *file_srgb_intent));
+PNG_EXPORT(155, png_uint_32, png_get_sRGB, (png_const_structrp png_ptr,
+    png_const_inforp info_ptr, int *file_srgb_intent));
 #endif
 
 #ifdef PNG_sRGB_SUPPORTED
-PNG_EXPORT(156, void, png_set_sRGB,
-    (png_structp png_ptr, png_infop info_ptr, int srgb_intent));
-PNG_EXPORT(157, void, png_set_sRGB_gAMA_and_cHRM, (png_structp png_ptr,
-    png_infop info_ptr, int srgb_intent));
+PNG_EXPORT(156, void, png_set_sRGB, (png_const_structrp png_ptr,
+    png_inforp info_ptr, int srgb_intent));
+PNG_EXPORT(157, void, png_set_sRGB_gAMA_and_cHRM, (png_const_structrp png_ptr,
+    png_inforp info_ptr, int srgb_intent));
 #endif
 
 #ifdef PNG_iCCP_SUPPORTED
-PNG_EXPORT(158, png_uint_32, png_get_iCCP,
-    (png_const_structp png_ptr, png_const_infop info_ptr,
-    png_charpp name, int *compression_type, png_bytepp profile,
-    png_uint_32 *proflen));
+PNG_EXPORT(158, png_uint_32, png_get_iCCP, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_charpp name, int *compression_type,
+    png_bytepp profile, png_uint_32 *proflen));
 #endif
 
 #ifdef PNG_iCCP_SUPPORTED
-PNG_EXPORT(159, void, png_set_iCCP,
-    (png_structp png_ptr, png_infop info_ptr,
-    png_const_charp name, int compression_type, png_const_bytep profile,
-    png_uint_32 proflen));
+PNG_EXPORT(159, void, png_set_iCCP, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_const_charp name, int compression_type,
+    png_const_bytep profile, png_uint_32 proflen));
 #endif
 
 #ifdef PNG_sPLT_SUPPORTED
-PNG_EXPORT(160, png_uint_32, png_get_sPLT,
-    (png_const_structp png_ptr, png_const_infop info_ptr,
-    png_sPLT_tpp entries));
+PNG_EXPORT(160, int, png_get_sPLT, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_sPLT_tpp entries));
 #endif
 
 #ifdef PNG_sPLT_SUPPORTED
-PNG_EXPORT(161, void, png_set_sPLT,
-    (png_structp png_ptr, png_infop info_ptr,
-    png_const_sPLT_tp entries, int nentries));
+PNG_EXPORT(161, void, png_set_sPLT, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_const_sPLT_tp entries, int nentries));
 #endif
 
 #ifdef PNG_TEXT_SUPPORTED
 /* png_get_text also returns the number of text chunks in *num_text */
-PNG_EXPORT(162, png_uint_32, png_get_text,
-    (png_const_structp png_ptr, png_const_infop info_ptr,
-    png_textp *text_ptr, int *num_text));
+PNG_EXPORT(162, int, png_get_text, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_textp *text_ptr, int *num_text));
 #endif
 
 /* Note while png_set_text() will accept a structure whose text,
@@ -2277,122 +2284,220 @@ PNG_EXPORT(162, png_uint_32, png_get_text,
  */
 
 #ifdef PNG_TEXT_SUPPORTED
-PNG_EXPORT(163, void, png_set_text,
-    (png_structp png_ptr, png_infop info_ptr,
-    png_const_textp text_ptr, int num_text));
+PNG_EXPORT(163, void, png_set_text, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_const_textp text_ptr, int num_text));
 #endif
 
 #ifdef PNG_tIME_SUPPORTED
-PNG_EXPORT(164, png_uint_32, png_get_tIME,
-    (png_const_structp png_ptr, png_infop info_ptr, png_timep *mod_time));
+PNG_EXPORT(164, png_uint_32, png_get_tIME, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_timep *mod_time));
 #endif
 
 #ifdef PNG_tIME_SUPPORTED
-PNG_EXPORT(165, void, png_set_tIME,
-    (png_structp png_ptr, png_infop info_ptr, png_const_timep mod_time));
+PNG_EXPORT(165, void, png_set_tIME, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_const_timep mod_time));
 #endif
 
 #ifdef PNG_tRNS_SUPPORTED
-PNG_EXPORT(166, png_uint_32, png_get_tRNS,
-    (png_const_structp png_ptr, png_infop info_ptr,
-    png_bytep *trans_alpha, int *num_trans, png_color_16p *trans_color));
+PNG_EXPORT(166, png_uint_32, png_get_tRNS, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_bytep *trans_alpha, int *num_trans,
+    png_color_16p *trans_color));
 #endif
 
 #ifdef PNG_tRNS_SUPPORTED
-PNG_EXPORT(167, void, png_set_tRNS,
-    (png_structp png_ptr, png_infop info_ptr,
-    png_const_bytep trans_alpha, int num_trans,
+PNG_EXPORT(167, void, png_set_tRNS, (png_structrp png_ptr,
+    png_inforp info_ptr, png_const_bytep trans_alpha, int num_trans,
     png_const_color_16p trans_color));
 #endif
 
 #ifdef PNG_sCAL_SUPPORTED
-PNG_FP_EXPORT(168, png_uint_32, png_get_sCAL,
-    (png_const_structp png_ptr, png_const_infop info_ptr,
-    int *unit, double *width, double *height));
-#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
+PNG_FP_EXPORT(168, png_uint_32, png_get_sCAL, (png_const_structrp png_ptr,
+    png_const_inforp info_ptr, int *unit, double *width, double *height))
+#if defined(PNG_FLOATING_ARITHMETIC_SUPPORTED) || \
+   defined(PNG_FLOATING_POINT_SUPPORTED)
 /* NOTE: this API is currently implemented using floating point arithmetic,
  * consequently it can only be used on systems with floating point support.
  * In any case the range of values supported by png_fixed_point is small and it
  * is highly recommended that png_get_sCAL_s be used instead.
  */
 PNG_FIXED_EXPORT(214, png_uint_32, png_get_sCAL_fixed,
-    (png_structp png_ptr, png_const_infop info_ptr, int *unit,
-    png_fixed_point *width,
-    png_fixed_point *height));
+    (png_const_structrp png_ptr, png_const_inforp info_ptr, int *unit,
+    png_fixed_point *width, png_fixed_point *height))
 #endif
 PNG_EXPORT(169, png_uint_32, png_get_sCAL_s,
-    (png_const_structp png_ptr, png_const_infop info_ptr,
-    int *unit, png_charpp swidth, png_charpp sheight));
-
-PNG_FP_EXPORT(170, void, png_set_sCAL,
-    (png_structp png_ptr, png_infop info_ptr,
-    int unit, double width, double height));
-PNG_FIXED_EXPORT(213, void, png_set_sCAL_fixed, (png_structp png_ptr,
-   png_infop info_ptr, int unit, png_fixed_point width,
-   png_fixed_point height));
-PNG_EXPORT(171, void, png_set_sCAL_s,
-    (png_structp png_ptr, png_infop info_ptr,
-    int unit, png_const_charp swidth, png_const_charp sheight));
-#endif /* PNG_sCAL_SUPPORTED */
-
-#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
-/* Provide a list of chunks and how they are to be handled, if the built-in
-   handling or default unknown chunk handling is not desired.  Any chunks not
-   listed will be handled in the default manner.  The IHDR and IEND chunks
-   must not be listed.  Because this turns off the default handling for chunks
-   that would otherwise be recognized the behavior of libpng transformations may
-   well become incorrect!
-      keep = 0: PNG_HANDLE_CHUNK_AS_DEFAULT: follow default behavior
-           = 1: PNG_HANDLE_CHUNK_NEVER:      do not keep
-           = 2: PNG_HANDLE_CHUNK_IF_SAFE:    keep only if safe-to-copy
-           = 3: PNG_HANDLE_CHUNK_ALWAYS:     keep even if unsafe-to-copy
-*/
-PNG_EXPORT(172, void, png_set_keep_unknown_chunks,
-    (png_structp png_ptr, int keep,
-    png_const_bytep chunk_list, int num_chunks));
-
-/* The handling code is returned; the result is therefore true (non-zero) if
- * special handling is required, false for the default handling.
- */
-PNG_EXPORT(173, int, png_handle_as_unknown, (png_structp png_ptr,
+    (png_const_structrp png_ptr, png_const_inforp info_ptr, int *unit,
+    png_charpp swidth, png_charpp sheight));
+
+PNG_FP_EXPORT(170, void, png_set_sCAL, (png_const_structrp png_ptr,
+    png_inforp info_ptr, int unit, double width, double height))
+PNG_FIXED_EXPORT(213, void, png_set_sCAL_fixed, (png_const_structrp png_ptr,
+   png_inforp info_ptr, int unit, png_fixed_point width,
+   png_fixed_point height))
+PNG_EXPORT(171, void, png_set_sCAL_s, (png_const_structrp png_ptr,
+    png_inforp info_ptr, int unit,
+    png_const_charp swidth, png_const_charp sheight));
+#endif /* sCAL */
+
+#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
+/* Provide the default handling for all unknown chunks or, optionally, for
+ * specific unknown chunks.
+ *
+ * NOTE: prior to 1.6.0 the handling specified for particular chunks on read was
+ * ignored and the default was used, the per-chunk setting only had an effect on
+ * write.  If you wish to have chunk-specific handling on read in code that must
+ * work on earlier versions you must use a user chunk callback to specify the
+ * desired handling (keep or discard.)
+ *
+ * The 'keep' parameter is a PNG_HANDLE_CHUNK_ value as listed below.  The
+ * parameter is interpreted as follows:
+ *
+ * READ:
+ *    PNG_HANDLE_CHUNK_AS_DEFAULT:
+ *       Known chunks: do normal libpng processing, do not keep the chunk (but
+ *          see the comments below about PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
+ *       Unknown chunks: for a specific chunk use the global default, when used
+ *          as the default discard the chunk data.
+ *    PNG_HANDLE_CHUNK_NEVER:
+ *       Discard the chunk data.
+ *    PNG_HANDLE_CHUNK_IF_SAFE:
+ *       Keep the chunk data if the chunk is not critical else raise a chunk
+ *       error.
+ *    PNG_HANDLE_CHUNK_ALWAYS:
+ *       Keep the chunk data.
+ *
+ * If the chunk data is saved it can be retrieved using png_get_unknown_chunks,
+ * below.  Notice that specifying "AS_DEFAULT" as a global default is equivalent
+ * to specifying "NEVER", however when "AS_DEFAULT" is used for specific chunks
+ * it simply resets the behavior to the libpng default.
+ *
+ * INTERACTION WTIH USER CHUNK CALLBACKS:
+ * The per-chunk handling is always used when there is a png_user_chunk_ptr
+ * callback and the callback returns 0; the chunk is then always stored *unless*
+ * it is critical and the per-chunk setting is other than ALWAYS.  Notice that
+ * the global default is *not* used in this case.  (In effect the per-chunk
+ * value is incremented to at least IF_SAFE.)
+ *
+ * IMPORTANT NOTE: this behavior will change in libpng 1.7 - the global and
+ * per-chunk defaults will be honored.  If you want to preserve the current
+ * behavior when your callback returns 0 you must set PNG_HANDLE_CHUNK_IF_SAFE
+ * as the default - if you don't do this libpng 1.6 will issue a warning.
+ *
+ * If you want unhandled unknown chunks to be discarded in libpng 1.6 and
+ * earlier simply return '1' (handled).
+ *
+ * PNG_HANDLE_AS_UNKNOWN_SUPPORTED:
+ *    If this is *not* set known chunks will always be handled by libpng and
+ *    will never be stored in the unknown chunk list.  Known chunks listed to
+ *    png_set_keep_unknown_chunks will have no effect.  If it is set then known
+ *    chunks listed with a keep other than AS_DEFAULT will *never* be processed
+ *    by libpng, in addition critical chunks must either be processed by the
+ *    callback or saved.
+ *
+ *    The IHDR and IEND chunks must not be listed.  Because this turns off the
+ *    default handling for chunks that would otherwise be recognized the
+ *    behavior of libpng transformations may well become incorrect!
+ *
+ * WRITE:
+ *    When writing chunks the options only apply to the chunks specified by
+ *    png_set_unknown_chunks (below), libpng will *always* write known chunks
+ *    required by png_set_ calls and will always write the core critical chunks
+ *    (as required for PLTE).
+ *
+ *    Each chunk in the png_set_unknown_chunks list is looked up in the
+ *    png_set_keep_unknown_chunks list to find the keep setting, this is then
+ *    interpreted as follows:
+ *
+ *    PNG_HANDLE_CHUNK_AS_DEFAULT:
+ *       Write safe-to-copy chunks and write other chunks if the global
+ *       default is set to _ALWAYS, otherwise don't write this chunk.
+ *    PNG_HANDLE_CHUNK_NEVER:
+ *       Do not write the chunk.
+ *    PNG_HANDLE_CHUNK_IF_SAFE:
+ *       Write the chunk if it is safe-to-copy, otherwise do not write it.
+ *    PNG_HANDLE_CHUNK_ALWAYS:
+ *       Write the chunk.
+ *
+ * Note that the default behavior is effectively the opposite of the read case -
+ * in read unknown chunks are not stored by default, in write they are written
+ * by default.  Also the behavior of PNG_HANDLE_CHUNK_IF_SAFE is very different
+ * - on write the safe-to-copy bit is checked, on read the critical bit is
+ * checked and on read if the chunk is critical an error will be raised.
+ *
+ * num_chunks:
+ * ===========
+ *    If num_chunks is positive, then the "keep" parameter specifies the manner
+ *    for handling only those chunks appearing in the chunk_list array,
+ *    otherwise the chunk list array is ignored.
+ *
+ *    If num_chunks is 0 the "keep" parameter specifies the default behavior for
+ *    unknown chunks, as described above.
+ *
+ *    If num_chunks is negative, then the "keep" parameter specifies the manner
+ *    for handling all unknown chunks plus all chunks recognized by libpng
+ *    except for the IHDR, PLTE, tRNS, IDAT, and IEND chunks (which continue to
+ *    be processed by libpng.
+ */
+PNG_EXPORT(172, void, png_set_keep_unknown_chunks, (png_structrp png_ptr,
+    int keep, png_const_bytep chunk_list, int num_chunks));
+
+/* The "keep" PNG_HANDLE_CHUNK_ parameter for the specified chunk is returned;
+ * the result is therefore true (non-zero) if special handling is required,
+ * false for the default handling.
+ */
+PNG_EXPORT(173, int, png_handle_as_unknown, (png_const_structrp png_ptr,
     png_const_bytep chunk_name));
 #endif
-#ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
-PNG_EXPORT(174, void, png_set_unknown_chunks, (png_structp png_ptr,
-    png_infop info_ptr, png_const_unknown_chunkp unknowns,
+
+#ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
+PNG_EXPORT(174, void, png_set_unknown_chunks, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_const_unknown_chunkp unknowns,
     int num_unknowns));
+   /* NOTE: prior to 1.6.0 this routine set the 'location' field of the added
+    * unknowns to the location currently stored in the png_struct.  This is
+    * invariably the wrong value on write.  To fix this call the following API
+    * for each chunk in the list with the correct location.  If you know your
+    * code won't be compiled on earlier versions you can rely on
+    * png_set_unknown_chunks(write-ptr, png_get_unknown_chunks(read-ptr)) doing
+    * the correct thing.
+    */
+
 PNG_EXPORT(175, void, png_set_unknown_chunk_location,
-    (png_structp png_ptr, png_infop info_ptr, int chunk, int location));
-PNG_EXPORT(176, int, png_get_unknown_chunks, (png_const_structp png_ptr,
-    png_const_infop info_ptr, png_unknown_chunkpp entries));
+    (png_const_structrp png_ptr, png_inforp info_ptr, int chunk, int location));
+
+PNG_EXPORT(176, int, png_get_unknown_chunks, (png_const_structrp png_ptr,
+    png_inforp info_ptr, png_unknown_chunkpp entries));
 #endif
 
 /* Png_free_data() will turn off the "valid" flag for anything it frees.
  * If you need to turn it off for a chunk that your application has freed,
  * you can use png_set_invalid(png_ptr, info_ptr, PNG_INFO_CHNK);
  */
-PNG_EXPORT(177, void, png_set_invalid,
-    (png_structp png_ptr, png_infop info_ptr, int mask));
+PNG_EXPORT(177, void, png_set_invalid, (png_const_structrp png_ptr,
+    png_inforp info_ptr, int mask));
 
 #ifdef PNG_INFO_IMAGE_SUPPORTED
 /* The "params" pointer is currently not used and is for future expansion. */
-PNG_EXPORT(178, void, png_read_png, (png_structp png_ptr, png_infop info_ptr,
+#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
+PNG_EXPORT(178, void, png_read_png, (png_structrp png_ptr, png_inforp info_ptr,
     int transforms, png_voidp params));
-PNG_EXPORT(179, void, png_write_png, (png_structp png_ptr, png_infop info_ptr,
+#endif
+#ifdef PNG_WRITE_SUPPORTED
+PNG_EXPORT(179, void, png_write_png, (png_structrp png_ptr, png_inforp info_ptr,
     int transforms, png_voidp params));
 #endif
+#endif
 
 PNG_EXPORT(180, png_const_charp, png_get_copyright,
-    (png_const_structp png_ptr));
+    (png_const_structrp png_ptr));
 PNG_EXPORT(181, png_const_charp, png_get_header_ver,
-    (png_const_structp png_ptr));
+    (png_const_structrp png_ptr));
 PNG_EXPORT(182, png_const_charp, png_get_header_version,
-    (png_const_structp png_ptr));
+    (png_const_structrp png_ptr));
 PNG_EXPORT(183, png_const_charp, png_get_libpng_ver,
-    (png_const_structp png_ptr));
+    (png_const_structrp png_ptr));
 
 #ifdef PNG_MNG_FEATURES_SUPPORTED
-PNG_EXPORT(184, png_uint_32, png_permit_mng_features, (png_structp png_ptr,
+PNG_EXPORT(184, png_uint_32, png_permit_mng_features, (png_structrp png_ptr,
     png_uint_32 mng_features_permitted));
 #endif
 
@@ -2401,75 +2506,77 @@ PNG_EXPORT(184, png_uint_32, png_permit_mng_features, (png_structp png_ptr,
 #define PNG_HANDLE_CHUNK_NEVER        1
 #define PNG_HANDLE_CHUNK_IF_SAFE      2
 #define PNG_HANDLE_CHUNK_ALWAYS       3
+#define PNG_HANDLE_CHUNK_LAST         4
 
 /* Strip the prepended error numbers ("#nnn ") from error and warning
  * messages before passing them to the error or warning handler.
  */
 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
-PNG_EXPORT(185, void, png_set_strip_error_numbers,
-    (png_structp png_ptr,
+PNG_EXPORT(185, void, png_set_strip_error_numbers, (png_structrp png_ptr,
     png_uint_32 strip_mode));
 #endif
 
 /* Added in libpng-1.2.6 */
 #ifdef PNG_SET_USER_LIMITS_SUPPORTED
-PNG_EXPORT(186, void, png_set_user_limits, (png_structp png_ptr,
+PNG_EXPORT(186, void, png_set_user_limits, (png_structrp png_ptr,
     png_uint_32 user_width_max, png_uint_32 user_height_max));
 PNG_EXPORT(187, png_uint_32, png_get_user_width_max,
-    (png_const_structp png_ptr));
+    (png_const_structrp png_ptr));
 PNG_EXPORT(188, png_uint_32, png_get_user_height_max,
-    (png_const_structp png_ptr));
+    (png_const_structrp png_ptr));
 /* Added in libpng-1.4.0 */
-PNG_EXPORT(189, void, png_set_chunk_cache_max, (png_structp png_ptr,
+PNG_EXPORT(189, void, png_set_chunk_cache_max, (png_structrp png_ptr,
     png_uint_32 user_chunk_cache_max));
 PNG_EXPORT(190, png_uint_32, png_get_chunk_cache_max,
-    (png_const_structp png_ptr));
+    (png_const_structrp png_ptr));
 /* Added in libpng-1.4.1 */
-PNG_EXPORT(191, void, png_set_chunk_malloc_max, (png_structp png_ptr,
+PNG_EXPORT(191, void, png_set_chunk_malloc_max, (png_structrp png_ptr,
     png_alloc_size_t user_chunk_cache_max));
 PNG_EXPORT(192, png_alloc_size_t, png_get_chunk_malloc_max,
-    (png_const_structp png_ptr));
+    (png_const_structrp png_ptr));
 #endif
 
 #if defined(PNG_INCH_CONVERSIONS_SUPPORTED)
 PNG_EXPORT(193, png_uint_32, png_get_pixels_per_inch,
-    (png_const_structp png_ptr, png_const_infop info_ptr));
+    (png_const_structrp png_ptr, png_const_inforp info_ptr));
 
 PNG_EXPORT(194, png_uint_32, png_get_x_pixels_per_inch,
-    (png_const_structp png_ptr, png_const_infop info_ptr));
+    (png_const_structrp png_ptr, png_const_inforp info_ptr));
 
 PNG_EXPORT(195, png_uint_32, png_get_y_pixels_per_inch,
-    (png_const_structp png_ptr, png_const_infop info_ptr));
+    (png_const_structrp png_ptr, png_const_inforp info_ptr));
 
 PNG_FP_EXPORT(196, float, png_get_x_offset_inches,
-    (png_const_structp png_ptr, png_const_infop info_ptr));
+    (png_const_structrp png_ptr, png_const_inforp info_ptr))
 #ifdef PNG_FIXED_POINT_SUPPORTED /* otherwise not implemented. */
 PNG_FIXED_EXPORT(211, png_fixed_point, png_get_x_offset_inches_fixed,
-    (png_structp png_ptr, png_const_infop info_ptr));
+    (png_const_structrp png_ptr, png_const_inforp info_ptr))
 #endif
 
-PNG_FP_EXPORT(197, float, png_get_y_offset_inches, (png_const_structp png_ptr,
-    png_const_infop info_ptr));
+PNG_FP_EXPORT(197, float, png_get_y_offset_inches, (png_const_structrp png_ptr,
+    png_const_inforp info_ptr))
 #ifdef PNG_FIXED_POINT_SUPPORTED /* otherwise not implemented. */
 PNG_FIXED_EXPORT(212, png_fixed_point, png_get_y_offset_inches_fixed,
-    (png_structp png_ptr, png_const_infop info_ptr));
+    (png_const_structrp png_ptr, png_const_inforp info_ptr))
 #endif
 
 #  ifdef PNG_pHYs_SUPPORTED
-PNG_EXPORT(198, png_uint_32, png_get_pHYs_dpi, (png_const_structp png_ptr,
-    png_const_infop info_ptr, png_uint_32 *res_x, png_uint_32 *res_y,
+PNG_EXPORT(198, png_uint_32, png_get_pHYs_dpi, (png_const_structrp png_ptr,
+    png_const_inforp info_ptr, png_uint_32 *res_x, png_uint_32 *res_y,
     int *unit_type));
-#  endif /* PNG_pHYs_SUPPORTED */
-#endif  /* PNG_INCH_CONVERSIONS_SUPPORTED */
+#  endif /* pHYs */
+#endif  /* INCH_CONVERSIONS */
 
 /* Added in libpng-1.4.0 */
 #ifdef PNG_IO_STATE_SUPPORTED
-PNG_EXPORT(199, png_uint_32, png_get_io_state, (png_structp png_ptr));
+PNG_EXPORT(199, png_uint_32, png_get_io_state, (png_const_structrp png_ptr));
+
+/* Removed from libpng 1.6; use png_get_io_chunk_type. */
+PNG_REMOVED(200, png_const_bytep, png_get_io_chunk_name, (png_structrp png_ptr),
+    PNG_DEPRECATED)
 
-PNG_EXPORTA(200, png_const_bytep, png_get_io_chunk_name,
-    (png_structp png_ptr), PNG_DEPRECATED);
 PNG_EXPORT(216, png_uint_32, png_get_io_chunk_type,
-    (png_const_structp png_ptr));
+    (png_const_structrp png_ptr));
 
 /* The flags returned by png_get_io_state() are the following: */
 #  define PNG_IO_NONE        0x0000   /* no I/O at this moment */
@@ -2481,7 +2588,7 @@ PNG_EXPORT(216, png_uint_32, png_get_io_chunk_type,
 #  define PNG_IO_CHUNK_CRC   0x0080   /* currently at the chunk crc */
 #  define PNG_IO_MASK_OP     0x000f   /* current operation: reading/writing */
 #  define PNG_IO_MASK_LOC    0x00f0   /* current location: sig/hdr/data/crc */
-#endif /* ?PNG_IO_STATE_SUPPORTED */
+#endif /* IO_STATE */
 
 /* Interlace support.  The following macros are always defined so that if
  * libpng interlace handling is turned off the macros may be used to handle
@@ -2525,10 +2632,10 @@ PNG_EXPORT(216, png_uint_32, png_get_io_chunk_type,
  * necessary to find the row in the output image given a row in an interlaced
  * image, so two more macros:
  */
-#define PNG_ROW_FROM_PASS_ROW(yIn, pass) \
-   (((yIn)<<PNG_PASS_ROW_SHIFT(pass))+PNG_PASS_START_ROW(pass))
-#define PNG_COL_FROM_PASS_COL(xIn, pass) \
-   (((xIn)<<PNG_PASS_COL_SHIFT(pass))+PNG_PASS_START_COL(pass))
+#define PNG_ROW_FROM_PASS_ROW(y_in, pass) \
+   (((y_in)<<PNG_PASS_ROW_SHIFT(pass))+PNG_PASS_START_ROW(pass))
+#define PNG_COL_FROM_PASS_COL(x_in, pass) \
+   (((x_in)<<PNG_PASS_COL_SHIFT(pass))+PNG_PASS_START_COL(pass))
 
 /* Two macros which return a boolean (0 or 1) saying whether the given row
  * or column is in a particular pass.  These use a common utility macro that
@@ -2565,27 +2672,29 @@ PNG_EXPORT(216, png_uint_32, png_get_io_chunk_type,
            * (png_uint_16)(alpha)                         \
            + (png_uint_16)(bg)*(png_uint_16)(255          \
            - (png_uint_16)(alpha)) + 128);                \
-       (composite) = (png_byte)((temp + (temp >> 8)) >> 8); }
+       (composite) = (png_byte)(((temp + (temp >> 8)) >> 8) & 0xff); }
 
 #  define png_composite_16(composite, fg, alpha, bg)       \
      { png_uint_32 temp = (png_uint_32)((png_uint_32)(fg)  \
            * (png_uint_32)(alpha)                          \
            + (png_uint_32)(bg)*(65535                      \
            - (png_uint_32)(alpha)) + 32768);               \
-       (composite) = (png_uint_16)((temp + (temp >> 16)) >> 16); }
+       (composite) = (png_uint_16)(0xffff & ((temp + (temp >> 16)) >> 16)); }
 
 #else  /* Standard method using integer division */
 
-#  define png_composite(composite, fg, alpha, bg)                          \
-     (composite) = (png_byte)(((png_uint_16)(fg) * (png_uint_16)(alpha) +  \
-     (png_uint_16)(bg) * (png_uint_16)(255 - (png_uint_16)(alpha)) +       \
-     127) / 255)
+#  define png_composite(composite, fg, alpha, bg)                        \
+     (composite) =                                                       \
+         (png_byte)(0xff & (((png_uint_16)(fg) * (png_uint_16)(alpha) +  \
+         (png_uint_16)(bg) * (png_uint_16)(255 - (png_uint_16)(alpha)) + \
+         127) / 255))
 
 #  define png_composite_16(composite, fg, alpha, bg)                         \
-     (composite) = (png_uint_16)(((png_uint_32)(fg) * (png_uint_32)(alpha) + \
-     (png_uint_32)(bg)*(png_uint_32)(65535 - (png_uint_32)(alpha)) +         \
-     32767) / 65535)
-#endif /* PNG_READ_COMPOSITE_NODIV_SUPPORTED */
+     (composite) =                                                           \
+         (png_uint_16)(0xffff & (((png_uint_32)(fg) * (png_uint_32)(alpha) + \
+         (png_uint_32)(bg)*(png_uint_32)(65535 - (png_uint_32)(alpha)) +     \
+         32767) / 65535))
+#endif /* READ_COMPOSITE_NODIV */
 
 #ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED
 PNG_EXPORT(201, png_uint_32, png_get_uint_32, (png_const_bytep buf));
@@ -2593,7 +2702,7 @@ PNG_EXPORT(202, png_uint_16, png_get_uint_16, (png_const_bytep buf));
 PNG_EXPORT(203, png_int_32, png_get_int_32, (png_const_bytep buf));
 #endif
 
-PNG_EXPORT(204, png_uint_32, png_get_uint_31, (png_structp png_ptr,
+PNG_EXPORT(204, png_uint_32, png_get_uint_31, (png_const_structrp png_ptr,
     png_const_bytep buf));
 /* No png_get_int_16 -- may be added if there's a real need for it. */
 
@@ -2619,7 +2728,7 @@ PNG_EXPORT(207, void, png_save_uint_16, (png_bytep buf, unsigned int i));
  * The png_get_int_32() routine assumes we are using two's complement
  * format for negative values, which is almost certainly true.
  */
-#  define png_get_uint_32(buf) \
+#  define PNG_get_uint_32(buf) \
      (((png_uint_32)(*(buf)) << 24) + \
       ((png_uint_32)(*((buf) + 1)) << 16) + \
       ((png_uint_32)(*((buf) + 2)) << 8) + \
@@ -2628,33 +2737,550 @@ PNG_EXPORT(207, void, png_save_uint_16, (png_bytep buf, unsigned int i));
    /* From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
     * function) incorrectly returned a value of type png_uint_32.
     */
-#  define png_get_uint_16(buf) \
+#  define PNG_get_uint_16(buf) \
      ((png_uint_16) \
       (((unsigned int)(*(buf)) << 8) + \
        ((unsigned int)(*((buf) + 1)))))
 
-#  define png_get_int_32(buf) \
+#  define PNG_get_int_32(buf) \
      ((png_int_32)((*(buf) & 0x80) \
       ? -((png_int_32)((png_get_uint_32(buf) ^ 0xffffffffL) + 1)) \
       : (png_int_32)png_get_uint_32(buf)))
+
+   /* If PNG_PREFIX is defined the same thing as below happens in pnglibconf.h,
+    * but defining a macro name prefixed with PNG_PREFIX.
+    */
+#  ifndef PNG_PREFIX
+#     define png_get_uint_32(buf) PNG_get_uint_32(buf)
+#     define png_get_uint_16(buf) PNG_get_uint_16(buf)
+#     define png_get_int_32(buf)  PNG_get_int_32(buf)
+#  endif
+#else
+#  ifdef PNG_PREFIX
+      /* No macros; revert to the (redefined) function */
+#     define PNG_get_uint_32 (png_get_uint_32)
+#     define PNG_get_uint_16 (png_get_uint_16)
+#     define PNG_get_int_32  (png_get_int_32)
+#  endif
 #endif
 
-#if defined(PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED) || \
-    defined(PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED)
-PNG_EXPORT(234, void, png_set_check_for_invalid_index, (png_structp png_ptr,
-    int allowed));
+#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) || \
+    defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
+/*******************************************************************************
+ *  SIMPLIFIED API
+ *******************************************************************************
+ *
+ * Please read the documentation in libpng-manual.txt (TODO: write said
+ * documentation) if you don't understand what follows.
+ *
+ * The simplified API hides the details of both libpng and the PNG file format
+ * itself.  It allows PNG files to be read into a very limited number of
+ * in-memory bitmap formats or to be written from the same formats.  If these
+ * formats do not accomodate your needs then you can, and should, use the more
+ * sophisticated APIs above - these support a wide variety of in-memory formats
+ * and a wide variety of sophisticated transformations to those formats as well
+ * as a wide variety of APIs to manipulate ancillary information.
+ *
+ * To read a PNG file using the simplified API:
+ *
+ * 1) Declare a 'png_image' structure (see below) on the stack and set the
+ *    version field to PNG_IMAGE_VERSION.
+ * 2) Call the appropriate png_image_begin_read... function.
+ * 3) Set the png_image 'format' member to the required sample format.
+ * 4) Allocate a buffer for the image and, if required, the color-map.
+ * 5) Call png_image_finish_read to read the image and, if required, the
+ *    color-map into your buffers.
+ *
+ * There are no restrictions on the format of the PNG input itself; all valid
+ * color types, bit depths, and interlace methods are acceptable, and the
+ * input image is transformed as necessary to the requested in-memory format
+ * during the png_image_finish_read() step.  The only caveat is that if you
+ * request a color-mapped image from a PNG that is full-color or makes
+ * complex use of an alpha channel the transformation is extremely lossy and the
+ * result may look terrible.
+ *
+ * To write a PNG file using the simplified API:
+ *
+ * 1) Declare a 'png_image' structure on the stack and memset() it to all zero.
+ * 2) Initialize the members of the structure that describe the image, setting
+ *    the 'format' member to the format of the image samples.
+ * 3) Call the appropriate png_image_write... function with a pointer to the
+ *    image and, if necessary, the color-map to write the PNG data.
+ *
+ * png_image is a structure that describes the in-memory format of an image
+ * when it is being read or defines the in-memory format of an image that you
+ * need to write:
+ */
+#define PNG_IMAGE_VERSION 1
+
+typedef struct png_control *png_controlp;
+typedef struct
+{
+   png_controlp opaque;    /* Initialize to NULL, free with png_image_free */
+   png_uint_32  version;   /* Set to PNG_IMAGE_VERSION */
+   png_uint_32  width;     /* Image width in pixels (columns) */
+   png_uint_32  height;    /* Image height in pixels (rows) */
+   png_uint_32  format;    /* Image format as defined below */
+   png_uint_32  flags;     /* A bit mask containing informational flags */
+   png_uint_32  colormap_entries;
+                           /* Number of entries in the color-map */
+
+   /* In the event of an error or warning the following field will be set to a
+    * non-zero value and the 'message' field will contain a '\0' terminated
+    * string with the libpng error or warning message.  If both warnings and
+    * an error were encountered, only the error is recorded.  If there
+    * are multiple warnings, only the first one is recorded.
+    *
+    * The upper 30 bits of this value are reserved, the low two bits contain
+    * a value as follows:
+    */
+#  define PNG_IMAGE_WARNING 1
+#  define PNG_IMAGE_ERROR 2
+   /*
+    * The result is a two-bit code such that a value more than 1 indicates
+    * a failure in the API just called:
+    *
+    *    0 - no warning or error
+    *    1 - warning
+    *    2 - error
+    *    3 - error preceded by warning
+    */
+#  define PNG_IMAGE_FAILED(png_cntrl) ((((png_cntrl).warning_or_error)&0x03)>1)
+
+   png_uint_32  warning_or_error;
+
+   char         message[64];
+} png_image, *png_imagep;
+
+/* The samples of the image have one to four channels whose components have
+ * original values in the range 0 to 1.0:
+ *
+ * 1: A single gray or luminance channel (G).
+ * 2: A gray/luminance channel and an alpha channel (GA).
+ * 3: Three red, green, blue color channels (RGB).
+ * 4: Three color channels and an alpha channel (RGBA).
+ *
+ * The components are encoded in one of two ways:
+ *
+ * a) As a small integer, value 0..255, contained in a single byte.  For the
+ * alpha channel the original value is simply value/255.  For the color or
+ * luminance channels the value is encoded according to the sRGB specification
+ * and matches the 8-bit format expected by typical display devices.
+ *
+ * The color/gray channels are not scaled (pre-multiplied) by the alpha
+ * channel and are suitable for passing to color management software.
+ *
+ * b) As a value in the range 0..65535, contained in a 2-byte integer.  All
+ * channels can be converted to the original value by dividing by 65535; all
+ * channels are linear.  Color channels use the RGB encoding (RGB end-points) of
+ * the sRGB specification.  This encoding is identified by the
+ * PNG_FORMAT_FLAG_LINEAR flag below.
+ *
+ * When the simplified API needs to convert between sRGB and linear colorspaces,
+ * the actual sRGB transfer curve defined in the sRGB specification (see the
+ * article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
+ * approximation used elsewhere in libpng.
+ *
+ * When an alpha channel is present it is expected to denote pixel coverage
+ * of the color or luminance channels and is returned as an associated alpha
+ * channel: the color/gray channels are scaled (pre-multiplied) by the alpha
+ * value.
+ *
+ * The samples are either contained directly in the image data, between 1 and 8
+ * bytes per pixel according to the encoding, or are held in a color-map indexed
+ * by bytes in the image data.  In the case of a color-map the color-map entries
+ * are individual samples, encoded as above, and the image data has one byte per
+ * pixel to select the relevant sample from the color-map.
+ */
+
+/* PNG_FORMAT_*
+ *
+ * #defines to be used in png_image::format.  Each #define identifies a
+ * particular layout of sample data and, if present, alpha values.  There are
+ * separate defines for each of the two component encodings.
+ *
+ * A format is built up using single bit flag values.  All combinations are
+ * valid.  Formats can be built up from the flag values or you can use one of
+ * the predefined values below.  When testing formats always use the FORMAT_FLAG
+ * macros to test for individual features - future versions of the library may
+ * add new flags.
+ *
+ * When reading or writing color-mapped images the format should be set to the
+ * format of the entries in the color-map then png_image_{read,write}_colormap
+ * called to read or write the color-map and set the format correctly for the
+ * image data.  Do not set the PNG_FORMAT_FLAG_COLORMAP bit directly!
+ *
+ * NOTE: libpng can be built with particular features disabled, if you see
+ * compiler errors because the definition of one of the following flags has been
+ * compiled out it is because libpng does not have the required support.  It is
+ * possible, however, for the libpng configuration to enable the format on just
+ * read or just write; in that case you may see an error at run time.  You can
+ * guard against this by checking for the definition of the appropriate
+ * "_SUPPORTED" macro, one of:
+ *
+ *    PNG_SIMPLIFIED_{READ,WRITE}_{BGR,AFIRST}_SUPPORTED
+ */
+#define PNG_FORMAT_FLAG_ALPHA    0x01U /* format with an alpha channel */
+#define PNG_FORMAT_FLAG_COLOR    0x02U /* color format: otherwise grayscale */
+#define PNG_FORMAT_FLAG_LINEAR   0x04U /* 2 byte channels else 1 byte */
+#define PNG_FORMAT_FLAG_COLORMAP 0x08U /* image data is color-mapped */
+
+#ifdef PNG_FORMAT_BGR_SUPPORTED
+#  define PNG_FORMAT_FLAG_BGR    0x10U /* BGR colors, else order is RGB */
+#endif
+
+#ifdef PNG_FORMAT_AFIRST_SUPPORTED
+#  define PNG_FORMAT_FLAG_AFIRST 0x20U /* alpha channel comes first */
+#endif
+
+/* Commonly used formats have predefined macros.
+ *
+ * First the single byte (sRGB) formats:
+ */
+#define PNG_FORMAT_GRAY 0
+#define PNG_FORMAT_GA   PNG_FORMAT_FLAG_ALPHA
+#define PNG_FORMAT_AG   (PNG_FORMAT_GA|PNG_FORMAT_FLAG_AFIRST)
+#define PNG_FORMAT_RGB  PNG_FORMAT_FLAG_COLOR
+#define PNG_FORMAT_BGR  (PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_BGR)
+#define PNG_FORMAT_RGBA (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_ALPHA)
+#define PNG_FORMAT_ARGB (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_AFIRST)
+#define PNG_FORMAT_BGRA (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_ALPHA)
+#define PNG_FORMAT_ABGR (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_AFIRST)
+
+/* Then the linear 2-byte formats.  When naming these "Y" is used to
+ * indicate a luminance (gray) channel.
+ */
+#define PNG_FORMAT_LINEAR_Y PNG_FORMAT_FLAG_LINEAR
+#define PNG_FORMAT_LINEAR_Y_ALPHA (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_ALPHA)
+#define PNG_FORMAT_LINEAR_RGB (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR)
+#define PNG_FORMAT_LINEAR_RGB_ALPHA \
+   (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA)
+
+/* With color-mapped formats the image data is one byte for each pixel, the byte
+ * is an index into the color-map which is formatted as above.  To obtain a
+ * color-mapped format it is sufficient just to add the PNG_FOMAT_FLAG_COLORMAP
+ * to one of the above definitions, or you can use one of the definitions below.
+ */
+#define PNG_FORMAT_RGB_COLORMAP  (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_COLORMAP)
+#define PNG_FORMAT_BGR_COLORMAP  (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_COLORMAP)
+#define PNG_FORMAT_RGBA_COLORMAP (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_COLORMAP)
+#define PNG_FORMAT_ARGB_COLORMAP (PNG_FORMAT_ARGB|PNG_FORMAT_FLAG_COLORMAP)
+#define PNG_FORMAT_BGRA_COLORMAP (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_COLORMAP)
+#define PNG_FORMAT_ABGR_COLORMAP (PNG_FORMAT_ABGR|PNG_FORMAT_FLAG_COLORMAP)
+
+/* PNG_IMAGE macros
+ *
+ * These are convenience macros to derive information from a png_image
+ * structure.  The PNG_IMAGE_SAMPLE_ macros return values appropriate to the
+ * actual image sample values - either the entries in the color-map or the
+ * pixels in the image.  The PNG_IMAGE_PIXEL_ macros return corresponding values
+ * for the pixels and will always return 1 for color-mapped formats.  The
+ * remaining macros return information about the rows in the image and the
+ * complete image.
+ *
+ * NOTE: All the macros that take a png_image::format parameter are compile time
+ * constants if the format parameter is, itself, a constant.  Therefore these
+ * macros can be used in array declarations and case labels where required.
+ * Similarly the macros are also pre-processor constants (sizeof is not used) so
+ * they can be used in #if tests.
+ *
+ * First the information about the samples.
+ */
+#define PNG_IMAGE_SAMPLE_CHANNELS(fmt)\
+   (((fmt)&(PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA))+1)
+   /* Return the total number of channels in a given format: 1..4 */
+
+#define PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt)\
+   ((((fmt) & PNG_FORMAT_FLAG_LINEAR) >> 2)+1)
+   /* Return the size in bytes of a single component of a pixel or color-map
+    * entry (as appropriate) in the image: 1 or 2.
+    */
+
+#define PNG_IMAGE_SAMPLE_SIZE(fmt)\
+   (PNG_IMAGE_SAMPLE_CHANNELS(fmt) * PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt))
+   /* This is the size of the sample data for one sample.  If the image is
+    * color-mapped it is the size of one color-map entry (and image pixels are
+    * one byte in size), otherwise it is the size of one image pixel.
+    */
+
+#define PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(fmt)\
+   (PNG_IMAGE_SAMPLE_CHANNELS(fmt) * 256)
+   /* The maximum size of the color-map required by the format expressed in a
+    * count of components.  This can be used to compile-time allocate a
+    * color-map:
+    *
+    * png_uint_16 colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(linear_fmt)];
+    *
+    * png_byte colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(sRGB_fmt)];
+    *
+    * Alternatively use the PNG_IMAGE_COLORMAP_SIZE macro below to use the
+    * information from one of the png_image_begin_read_ APIs and dynamically
+    * allocate the required memory.
+    */
+
+/* Corresponding information about the pixels */
+#define PNG_IMAGE_PIXEL_(test,fmt)\
+   (((fmt)&PNG_FORMAT_FLAG_COLORMAP)?1:test(fmt))
+
+#define PNG_IMAGE_PIXEL_CHANNELS(fmt)\
+   PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_CHANNELS,fmt)
+   /* The number of separate channels (components) in a pixel; 1 for a
+    * color-mapped image.
+    */
+
+#define PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)\
+   PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_COMPONENT_SIZE,fmt)
+   /* The size, in bytes, of each component in a pixel; 1 for a color-mapped
+    * image.
+    */
+
+#define PNG_IMAGE_PIXEL_SIZE(fmt) PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_SIZE,fmt)
+   /* The size, in bytes, of a complete pixel; 1 for a color-mapped image. */
+
+/* Information about the whole row, or whole image */
+#define PNG_IMAGE_ROW_STRIDE(image)\
+   (PNG_IMAGE_PIXEL_CHANNELS((image).format) * (image).width)
+   /* Return the total number of components in a single row of the image; this
+    * is the minimum 'row stride', the minimum count of components between each
+    * row.  For a color-mapped image this is the minimum number of bytes in a
+    * row.
+    */
+
+#define PNG_IMAGE_BUFFER_SIZE(image, row_stride)\
+   (PNG_IMAGE_PIXEL_COMPONENT_SIZE((image).format)*(image).height*(row_stride))
+   /* Return the size, in bytes, of an image buffer given a png_image and a row
+    * stride - the number of components to leave space for in each row.
+    */
+
+#define PNG_IMAGE_SIZE(image)\
+   PNG_IMAGE_BUFFER_SIZE(image, PNG_IMAGE_ROW_STRIDE(image))
+   /* Return the size, in bytes, of the image in memory given just a png_image;
+    * the row stride is the minimum stride required for the image.
+    */
+
+#define PNG_IMAGE_COLORMAP_SIZE(image)\
+   (PNG_IMAGE_SAMPLE_SIZE((image).format) * (image).colormap_entries)
+   /* Return the size, in bytes, of the color-map of this image.  If the image
+    * format is not a color-map format this will return a size sufficient for
+    * 256 entries in the given format; check PNG_FORMAT_FLAG_COLORMAP if
+    * you don't want to allocate a color-map in this case.
+    */
+
+/* PNG_IMAGE_FLAG_*
+ *
+ * Flags containing additional information about the image are held in the
+ * 'flags' field of png_image.
+ */
+#define PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB 0x01
+   /* This indicates the the RGB values of the in-memory bitmap do not
+    * correspond to the red, green and blue end-points defined by sRGB.
+    */
+
+#define PNG_IMAGE_FLAG_FAST 0x02
+   /* On write emphasise speed over compression; the resultant PNG file will be
+    * larger but will be produced significantly faster, particular for large
+    * images.  Do not use this option for images which will be distributed, only
+    * used it when producing intermediate files that will be read back in
+    * repeatedly.  For a typical 24-bit image the option will double the read
+    * speed at the cost of increasing the image size by 25%, however for many
+    * more compressible images the PNG file can be 10 times larger with only a
+    * slight speed gain.
+    */
+
+#define PNG_IMAGE_FLAG_16BIT_sRGB 0x04
+   /* On read if the image is a 16-bit per component image and there is no gAMA
+    * or sRGB chunk assume that the components are sRGB encoded.  Notice that
+    * images output by the simplified API always have gamma information; setting
+    * this flag only affects the interpretation of 16-bit images from an
+    * external source.  It is recommended that the application expose this flag
+    * to the user; the user can normally easily recognize the difference between
+    * linear and sRGB encoding.  This flag has no effect on write - the data
+    * passed to the write APIs must have the correct encoding (as defined
+    * above.)
+    *
+    * If the flag is not set (the default) input 16-bit per component data is
+    * assumed to be linear.
+    *
+    * NOTE: the flag can only be set after the png_image_begin_read_ call,
+    * because that call initializes the 'flags' field.
+    */
+
+#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
+/* READ APIs
+ * ---------
+ *
+ * The png_image passed to the read APIs must have been initialized by setting
+ * the png_controlp field 'opaque' to NULL (or, safer, memset the whole thing.)
+ */
+#ifdef PNG_STDIO_SUPPORTED
+PNG_EXPORT(234, int, png_image_begin_read_from_file, (png_imagep image,
+   const char *file_name));
+   /* The named file is opened for read and the image header is filled in
+    * from the PNG header in the file.
+    */
+
+PNG_EXPORT(235, int, png_image_begin_read_from_stdio, (png_imagep image,
+   FILE* file));
+   /* The PNG header is read from the stdio FILE object. */
+#endif /* STDIO */
+
+PNG_EXPORT(236, int, png_image_begin_read_from_memory, (png_imagep image,
+   png_const_voidp memory, png_size_t size));
+   /* The PNG header is read from the given memory buffer. */
+
+PNG_EXPORT(237, int, png_image_finish_read, (png_imagep image,
+   png_const_colorp background, void *buffer, png_int_32 row_stride,
+   void *colormap));
+   /* Finish reading the image into the supplied buffer and clean up the
+    * png_image structure.
+    *
+    * row_stride is the step, in byte or 2-byte units as appropriate,
+    * between adjacent rows.  A positive stride indicates that the top-most row
+    * is first in the buffer - the normal top-down arrangement.  A negative
+    * stride indicates that the bottom-most row is first in the buffer.
+    *
+    * background need only be supplied if an alpha channel must be removed from
+    * a png_byte format and the removal is to be done by compositing on a solid
+    * color; otherwise it may be NULL and any composition will be done directly
+    * onto the buffer.  The value is an sRGB color to use for the background,
+    * for grayscale output the green channel is used.
+    *
+    * background must be supplied when an alpha channel must be removed from a
+    * single byte color-mapped output format, in other words if:
+    *
+    * 1) The original format from png_image_begin_read_from_* had
+    *    PNG_FORMAT_FLAG_ALPHA set.
+    * 2) The format set by the application does not.
+    * 3) The format set by the application has PNG_FORMAT_FLAG_COLORMAP set and
+    *    PNG_FORMAT_FLAG_LINEAR *not* set.
+    *
+    * For linear output removing the alpha channel is always done by compositing
+    * on black and background is ignored.
+    *
+    * colormap must be supplied when PNG_FORMAT_FLAG_COLORMAP is set.  It must
+    * be at least the size (in bytes) returned by PNG_IMAGE_COLORMAP_SIZE.
+    * image->colormap_entries will be updated to the actual number of entries
+    * written to the colormap; this may be less than the original value.
+    */
+
+PNG_EXPORT(238, void, png_image_free, (png_imagep image));
+   /* Free any data allocated by libpng in image->opaque, setting the pointer to
+    * NULL.  May be called at any time after the structure is initialized.
+    */
+#endif /* SIMPLIFIED_READ */
+
+#ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
+#ifdef PNG_STDIO_SUPPORTED
+/* WRITE APIS
+ * ----------
+ * For write you must initialize a png_image structure to describe the image to
+ * be written.  To do this use memset to set the whole structure to 0 then
+ * initialize fields describing your image.
+ *
+ * version: must be set to PNG_IMAGE_VERSION
+ * opaque: must be initialized to NULL
+ * width: image width in pixels
+ * height: image height in rows
+ * format: the format of the data (image and color-map) you wish to write
+ * flags: set to 0 unless one of the defined flags applies; set
+ *    PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB for color format images where the RGB
+ *    values do not correspond to the colors in sRGB.
+ * colormap_entries: set to the number of entries in the color-map (0 to 256)
+ */
+PNG_EXPORT(239, int, png_image_write_to_file, (png_imagep image,
+   const char *file, int convert_to_8bit, const void *buffer,
+   png_int_32 row_stride, const void *colormap));
+   /* Write the image to the named file. */
+
+PNG_EXPORT(240, int, png_image_write_to_stdio, (png_imagep image, FILE *file,
+   int convert_to_8_bit, const void *buffer, png_int_32 row_stride,
+   const void *colormap));
+   /* Write the image to the given (FILE*). */
+
+/* With both write APIs if image is in one of the linear formats with 16-bit
+ * data then setting convert_to_8_bit will cause the output to be an 8-bit PNG
+ * gamma encoded according to the sRGB specification, otherwise a 16-bit linear
+ * encoded PNG file is written.
+ *
+ * With color-mapped data formats the colormap parameter point to a color-map
+ * with at least image->colormap_entries encoded in the specified format.  If
+ * the format is linear the written PNG color-map will be converted to sRGB
+ * regardless of the convert_to_8_bit flag.
+ *
+ * With all APIs row_stride is handled as in the read APIs - it is the spacing
+ * from one row to the next in component sized units (1 or 2 bytes) and if
+ * negative indicates a bottom-up row layout in the buffer.
+ *
+ * Note that the write API does not support interlacing or sub-8-bit pixels.
+ */
+#endif /* STDIO */
+#endif /* SIMPLIFIED_WRITE */
+/*******************************************************************************
+ *  END OF SIMPLIFIED API
+ ******************************************************************************/
+#endif /* SIMPLIFIED_{READ|WRITE} */
+
+#ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
+PNG_EXPORT(242, void, png_set_check_for_invalid_index,
+    (png_structrp png_ptr, int allowed));
+#  ifdef PNG_GET_PALETTE_MAX_SUPPORTED
+PNG_EXPORT(243, int, png_get_palette_max, (png_const_structp png_ptr,
+    png_const_infop info_ptr));
+#  endif
+#endif /* CHECK_FOR_INVALID_INDEX */
+
+/*******************************************************************************
+ *  IMPLEMENTATION OPTIONS
+ *******************************************************************************
+ *
+ * Support for arbitrary implementation-specific optimizations.  The API allows
+ * particular options to be turned on or off.  'Option' is the number of the
+ * option and 'onoff' is 0 (off) or non-0 (on).  The value returned is given
+ * by the PNG_OPTION_ defines below.
+ *
+ * HARDWARE: normally hardware capabilites, such as the Intel SSE instructions,
+ *           are detected at run time, however sometimes it may be impossible
+ *           to do this in user mode, in which case it is necessary to discover
+ *           the capabilities in an OS specific way.  Such capabilities are
+ *           listed here when libpng has support for them and must be turned
+ *           ON by the application if present.
+ *
+ * SOFTWARE: sometimes software optimizations actually result in performance
+ *           decrease on some architectures or systems, or with some sets of
+ *           PNG images.  'Software' options allow such optimizations to be
+ *           selected at run time.
+ */
+#ifdef PNG_SET_OPTION_SUPPORTED
+#ifdef PNG_ARM_NEON_API_SUPPORTED
+#  define PNG_ARM_NEON   0 /* HARDWARE: ARM Neon SIMD instructions supported */
 #endif
+#define PNG_MAXIMUM_INFLATE_WINDOW 2 /* SOFTWARE: force maximum window */
+#define PNG_SKIP_sRGB_CHECK_PROFILE 4 /* SOFTWARE: Check ICC profile for sRGB */
+#define PNG_OPTION_NEXT  6 /* Next option - numbers must be even */
+
+/* Return values: NOTE: there are four values and 'off' is *not* zero */
+#define PNG_OPTION_UNSET   0 /* Unset - defaults to off */
+#define PNG_OPTION_INVALID 1 /* Option number out of range */
+#define PNG_OPTION_OFF     2
+#define PNG_OPTION_ON      3
+
+PNG_EXPORT(244, int, png_set_option, (png_structrp png_ptr, int option,
+   int onoff));
+#endif /* SET_OPTION */
+
+/*******************************************************************************
+ *  END OF HARDWARE AND SOFTWARE OPTIONS
+ ******************************************************************************/
 
-/* Maintainer: Put new public prototypes here ^, in libpng.3, and project
- * defs
+/* Maintainer: Put new public prototypes here ^, in libpng.3, in project
+ * defs, and in scripts/symbols.def.
  */
 
 /* The last ordinal number (this is the *last* one already used; the next
- * one to use is one more than this.)  Maintainer, remember to add an entry to
- * scripts/symbols.def as well.
+ * one to use is one more than this.)
  */
 #ifdef PNG_EXPORT_LAST_ORDINAL
-  PNG_EXPORT_LAST_ORDINAL(234);
+  PNG_EXPORT_LAST_ORDINAL(244);
 #endif
 
 #ifdef __cplusplus
diff --git a/src/3rdparty/libpng/pngconf.h b/src/3rdparty/libpng/pngconf.h
index 6f7ae8b..535c2df 100644
--- a/src/3rdparty/libpng/pngconf.h
+++ b/src/3rdparty/libpng/pngconf.h
@@ -1,9 +1,9 @@
 
 /* pngconf.h - machine configurable file for libpng
  *
- * libpng version 1.5.10 - March 29, 2012
+ * libpng version 1.6.17, March 26, 2015
  *
- * Copyright (c) 1998-2012 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
@@ -11,9 +11,7 @@
  * For conditions of distribution and use, see the disclaimer
  * and license in png.h
  *
- */
-
-/* Any machine specific code is near the front of this file, so if you
+ * Any machine specific code is near the front of this file, so if you
  * are configuring libpng for a machine, you may want to read the section
  * starting here down to where it starts to typedef png_color, png_text,
  * and png_info.
@@ -22,33 +20,49 @@
 #ifndef PNGCONF_H
 #define PNGCONF_H
 
-#ifndef PNG_BUILDING_SYMBOL_TABLE
-/* PNG_NO_LIMITS_H may be used to turn off the use of the standard C
- * definition file for  machine specific limits, this may impact the
- * correctness of the definitons below (see uses of INT_MAX).
- */
-#  ifndef PNG_NO_LIMITS_H
-#    include <limits.h>
-#  endif
+#ifndef PNG_BUILDING_SYMBOL_TABLE /* else includes may cause problems */
 
-/* For the memory copy APIs (i.e. the standard definitions of these),
- * because this file defines png_memcpy and so on the base APIs must
- * be defined here.
+/* From libpng 1.6.0 libpng requires an ANSI X3.159-1989 ("ISOC90") compliant C
+ * compiler for correct compilation.  The following header files are required by
+ * the standard.  If your compiler doesn't provide these header files, or they
+ * do not match the standard, you will need to provide/improve them.
  */
-#  if defined(BSD) && !defined(VXWORKS)
-#    include <strings.h>
-#  else
-#    include <string.h>
-#  endif
-
-/* For png_FILE_p - this provides the standard definition of a
- * FILE
+#include <limits.h>
+#include <stddef.h>
+
+/* Library header files.  These header files are all defined by ISOC90; libpng
+ * expects conformant implementations, however, an ISOC90 conformant system need
+ * not provide these header files if the functionality cannot be implemented.
+ * In this case it will be necessary to disable the relevant parts of libpng in
+ * the build of pnglibconf.h.
+ *
+ * Prior to 1.6.0 string.h was included here; the API changes in 1.6.0 to not
+ * include this unnecessary header file.
  */
-#  ifdef PNG_STDIO_SUPPORTED
-#    include <stdio.h>
-#  endif
+
+#ifdef PNG_STDIO_SUPPORTED
+   /* Required for the definition of FILE: */
+#  include <stdio.h>
+#endif
+
+#ifdef PNG_SETJMP_SUPPORTED
+   /* Required for the definition of jmp_buf and the declaration of longjmp: */
+#  include <setjmp.h>
 #endif
 
+#ifdef PNG_CONVERT_tIME_SUPPORTED
+   /* Required for struct tm: */
+#  include <time.h>
+#endif
+
+#endif /* PNG_BUILDING_SYMBOL_TABLE */
+
+/* Prior to 1.6.0 it was possible to turn off 'const' in declarations using
+ * PNG_NO_CONST; this is no longer supported except for data declarations which
+ * apparently still cause problems in 2011 on some compilers.
+ */
+#define PNG_CONST const /* backward compatibility only */
+
 /* This controls optimization of the reading of 16 and 32 bit values
  * from PNG files.  It can be set on a per-app-file basis - it
  * just changes whether a macro is used when the function is called.
@@ -72,28 +86,13 @@
  * may be changed on a per-file basis when compiling against libpng.
  */
 
-/* The PNGARG macro protects us against machines that don't have function
- * prototypes (ie K&R style headers).  If your compiler does not handle
- * function prototypes, define this macro and use the included ansi2knr.
- * I've always been able to use _NO_PROTO as the indicator, but you may
- * need to drag the empty declaration out in front of here, or change the
- * ifdef to suit your own needs.
+/* The PNGARG macro was used in versions of libpng prior to 1.6.0 to protect
+ * against legacy (pre ISOC90) compilers that did not understand function
+ * prototypes.  It is not required for modern C compilers.
  */
 #ifndef PNGARG
-
-#  ifdef OF /* zlib prototype munger */
-#    define PNGARG(arglist) OF(arglist)
-#  else
-
-#    ifdef _NO_PROTO
-#      define PNGARG(arglist) ()
-#    else
-#      define PNGARG(arglist) arglist
-#    endif /* _NO_PROTO */
-
-#  endif /* OF */
-
-#endif /* PNGARG */
+#  define PNGARG(arglist) arglist
+#endif
 
 /* Function calling conventions.
  * =============================
@@ -177,18 +176,16 @@
  * ==========================
  * This code is used at build time to find PNG_IMPEXP, the API settings
  * and PNG_EXPORT_TYPE(), it may also set a macro to indicate the DLL
- * import processing is possible.  On Windows/x86 systems it also sets
+ * import processing is possible.  On Windows systems it also sets
  * compiler-specific macros to the values required to change the calling
  * conventions of the various functions.
  */
-#if ( defined(_Windows) || defined(_WINDOWS) || defined(WIN32) ||\
-      defined(_WIN32) || defined(__WIN32__) || defined(__CYGWIN__) ) &&\
-    ( defined(_X86_) || defined(_X64_) || defined(_M_IX86) ||\
-      defined(_M_X64) || defined(_M_IA64) )
-  /* Windows system (DOS doesn't support DLLs) running on x86/x64.  Includes
-   * builds under Cygwin or MinGW.  Also includes Watcom builds but these need
-   * special treatment because they are not compatible with GCC or Visual C
-   * because of different calling conventions.
+#if defined(_Windows) || defined(_WINDOWS) || defined(WIN32) ||\
+    defined(_WIN32) || defined(__WIN32__) || defined(__CYGWIN__)
+  /* Windows system (DOS doesn't support DLLs).  Includes builds under Cygwin or
+   * MinGW on any architecture currently supported by Windows.  Also includes
+   * Watcom builds but these need special treatment because they are not
+   * compatible with GCC or Visual C because of different calling conventions.
    */
 #  if PNG_API_RULE == 2
     /* If this line results in an error, either because __watcall is not
@@ -202,6 +199,9 @@
 #  if defined(__GNUC__) || (defined (_MSC_VER) && (_MSC_VER >= 800)) || defined(__WINSCW__)
 #    define PNGCAPI __cdecl
 #    if PNG_API_RULE == 1
+       /* If this line results in an error __stdcall is not understood and
+        * PNG_API_RULE should not have been set to '1'.
+        */
 #      define PNGAPI __stdcall
 #    endif
 #  else
@@ -216,10 +216,11 @@
 #      define PNGAPI _stdcall
 #    endif
 #  endif /* compiler/api */
+
   /* NOTE: PNGCBAPI always defaults to PNGCAPI. */
 
 #  if defined(PNGAPI) && !defined(PNG_USER_PRIVATEBUILD)
-   ERROR: PNG_USER_PRIVATEBUILD must be defined if PNGAPI is changed
+#     error "PNG_USER_PRIVATEBUILD must be defined if PNGAPI is changed"
 #  endif
 
 #  if (defined(_MSC_VER) && _MSC_VER < 800) ||\
@@ -239,7 +240,7 @@
 #    endif
 #  endif /* compiler */
 
-#else /* !Windows/x86 */
+#else /* !Windows */
 #  if (defined(__IBMC__) || defined(__IBMCPP__)) && defined(__OS2__)
 #    define PNGAPI _System
 #  else /* !Windows/x86 && !OS/2 */
@@ -333,40 +334,73 @@
 
 #ifdef PNG_PEDANTIC_WARNINGS_SUPPORTED
   /* Support for compiler specific function attributes.  These are used
-   * so that where compiler support is available incorrect use of API
+   * so that where compiler support is available, incorrect use of API
    * functions in png.h will generate compiler warnings.  Added at libpng
-   * version 1.2.41.
+   * version 1.2.41.  Disabling these removes the warnings but may also produce
+   * less efficient code.
    */
-#  if defined(__GNUC__)
-#    ifndef PNG_USE_RESULT
+#  if defined(__clang__) && defined(__has_attribute)
+     /* Clang defines both __clang__ and __GNUC__. Check __clang__ first. */
+#    if !defined(PNG_USE_RESULT) && __has_attribute(__warn_unused_result__)
 #      define PNG_USE_RESULT __attribute__((__warn_unused_result__))
 #    endif
-#    ifndef PNG_NORETURN
-#      define PNG_NORETURN   __attribute__((__noreturn__))
+#    if !defined(PNG_NORETURN) && __has_attribute(__noreturn__)
+#      define PNG_NORETURN __attribute__((__noreturn__))
 #    endif
-#    ifndef PNG_ALLOCATED
-#      define PNG_ALLOCATED  __attribute__((__malloc__))
+#    if !defined(PNG_ALLOCATED) && __has_attribute(__malloc__)
+#      define PNG_ALLOCATED __attribute__((__malloc__))
 #    endif
-#    ifndef PNG_DEPRECATED
+#    if !defined(PNG_DEPRECATED) && __has_attribute(__deprecated__)
 #      define PNG_DEPRECATED __attribute__((__deprecated__))
 #    endif
-#    ifndef PNG_PRIVATE
-#      if 0 /* Doesn't work so we use deprecated instead*/
-#        define PNG_PRIVATE \
-          __attribute__((warning("This function is not exported by libpng.")))
-#      else
-#        define PNG_PRIVATE \
-          __attribute__((__deprecated__))
+#    if !defined(PNG_PRIVATE)
+#      ifdef __has_extension
+#        if __has_extension(attribute_unavailable_with_message)
+#          define PNG_PRIVATE __attribute__((__unavailable__(\
+             "This function is not exported by libpng.")))
+#        endif
 #      endif
 #    endif
-#  endif /* __GNUC__ */
+#    ifndef PNG_RESTRICT
+#      define PNG_RESTRICT __restrict
+#    endif
 
-#  if defined(_MSC_VER)  && (_MSC_VER >= 1300)
+#  elif defined(__GNUC__)
+#    ifndef PNG_USE_RESULT
+#      define PNG_USE_RESULT __attribute__((__warn_unused_result__))
+#    endif
+#    ifndef PNG_NORETURN
+#      define PNG_NORETURN   __attribute__((__noreturn__))
+#    endif
+#    if __GNUC__ >= 3
+#      ifndef PNG_ALLOCATED
+#        define PNG_ALLOCATED  __attribute__((__malloc__))
+#      endif
+#      ifndef PNG_DEPRECATED
+#        define PNG_DEPRECATED __attribute__((__deprecated__))
+#      endif
+#      ifndef PNG_PRIVATE
+#        if 0 /* Doesn't work so we use deprecated instead*/
+#          define PNG_PRIVATE \
+            __attribute__((warning("This function is not exported by libpng.")))
+#        else
+#          define PNG_PRIVATE \
+            __attribute__((__deprecated__))
+#        endif
+#      endif
+#      if ((__GNUC__ > 3) || !defined(__GNUC_MINOR__) || (__GNUC_MINOR__ >= 1))
+#        ifndef PNG_RESTRICT
+#          define PNG_RESTRICT __restrict
+#        endif
+#      endif /* __GNUC__.__GNUC_MINOR__ > 3.0 */
+#    endif /* __GNUC__ >= 3 */
+
+#  elif defined(_MSC_VER)  && (_MSC_VER >= 1300)
 #    ifndef PNG_USE_RESULT
 #      define PNG_USE_RESULT /* not supported */
 #    endif
 #    ifndef PNG_NORETURN
-#      define PNG_NORETURN __declspec(noreturn)
+#      define PNG_NORETURN   __declspec(noreturn)
 #    endif
 #    ifndef PNG_ALLOCATED
 #      if (_MSC_VER >= 1400)
@@ -379,7 +413,17 @@
 #    ifndef PNG_PRIVATE
 #      define PNG_PRIVATE __declspec(deprecated)
 #    endif
-#  endif /* _MSC_VER */
+#    ifndef PNG_RESTRICT
+#      if (_MSC_VER >= 1400)
+#        define PNG_RESTRICT __restrict
+#      endif
+#    endif
+
+#  elif defined(__WATCOMC__)
+#    ifndef PNG_RESTRICT
+#      define PNG_RESTRICT __restrict
+#    endif
+#  endif
 #endif /* PNG_PEDANTIC_WARNINGS */
 
 #ifndef PNG_DEPRECATED
@@ -397,10 +441,14 @@
 #ifndef PNG_PRIVATE
 #  define PNG_PRIVATE     /* This is a private libpng function */
 #endif
+#ifndef PNG_RESTRICT
+#  define PNG_RESTRICT    /* The C99 "restrict" feature */
+#endif
+
 #ifndef PNG_FP_EXPORT     /* A floating point API. */
 #  ifdef PNG_FLOATING_POINT_SUPPORTED
 #     define PNG_FP_EXPORT(ordinal, type, name, args)\
-         PNG_EXPORT(ordinal, type, name, args)
+         PNG_EXPORT(ordinal, type, name, args);
 #  else                   /* No floating point APIs */
 #     define PNG_FP_EXPORT(ordinal, type, name, args)
 #  endif
@@ -408,189 +456,167 @@
 #ifndef PNG_FIXED_EXPORT  /* A fixed point API. */
 #  ifdef PNG_FIXED_POINT_SUPPORTED
 #     define PNG_FIXED_EXPORT(ordinal, type, name, args)\
-         PNG_EXPORT(ordinal, type, name, args)
+         PNG_EXPORT(ordinal, type, name, args);
 #  else                   /* No fixed point APIs */
 #     define PNG_FIXED_EXPORT(ordinal, type, name, args)
 #  endif
 #endif
 
-/* The following uses const char * instead of char * for error
- * and warning message functions, so some compilers won't complain.
- * If you do not want to use const, define PNG_NO_CONST here.
+#ifndef PNG_BUILDING_SYMBOL_TABLE
+/* Some typedefs to get us started.  These should be safe on most of the common
+ * platforms.
+ *
+ * png_uint_32 and png_int_32 may, currently, be larger than required to hold a
+ * 32-bit value however this is not normally advisable.
+ *
+ * png_uint_16 and png_int_16 should always be two bytes in size - this is
+ * verified at library build time.
+ *
+ * png_byte must always be one byte in size.
  *
- * This should not change how the APIs are called, so it can be done
- * on a per-file basis in the application.
+ * The checks below use constants from limits.h, as defined by the ISOC90
+ * standard.
  */
-#ifndef PNG_CONST
-#  ifndef PNG_NO_CONST
-#    define PNG_CONST const
-#  else
-#    define PNG_CONST
-#  endif
+#if CHAR_BIT == 8 && UCHAR_MAX == 255
+   typedef unsigned char png_byte;
+#else
+#  error "libpng requires 8 bit bytes"
 #endif
 
-/* Some typedefs to get us started.  These should be safe on most of the
- * common platforms.  The typedefs should be at least as large as the
- * numbers suggest (a png_uint_32 must be at least 32 bits long), but they
- * don't have to be exactly that size.  Some compilers dislike passing
- * unsigned shorts as function parameters, so you may be better off using
- * unsigned int for png_uint_16.
- */
+#if INT_MIN == -32768 && INT_MAX == 32767
+   typedef int png_int_16;
+#elif SHRT_MIN == -32768 && SHRT_MAX == 32767
+   typedef short png_int_16;
+#else
+#  error "libpng requires a signed 16 bit type"
+#endif
 
-#if defined(INT_MAX) && (INT_MAX > 0x7ffffffeL)
-typedef unsigned int png_uint_32;
-typedef int png_int_32;
+#if UINT_MAX == 65535
+   typedef unsigned int png_uint_16;
+#elif USHRT_MAX == 65535
+   typedef unsigned short png_uint_16;
 #else
-typedef unsigned long png_uint_32;
-typedef long png_int_32;
+#  error "libpng requires an unsigned 16 bit type"
 #endif
-typedef unsigned short png_uint_16;
-typedef short png_int_16;
-typedef unsigned char png_byte;
 
-#ifdef PNG_NO_SIZE_T
-typedef unsigned int png_size_t;
+#if INT_MIN < -2147483646 && INT_MAX > 2147483646
+   typedef int png_int_32;
+#elif LONG_MIN < -2147483646 && LONG_MAX > 2147483646
+   typedef long int png_int_32;
 #else
-typedef size_t png_size_t;
+#  error "libpng requires a signed 32 bit (or more) type"
 #endif
-#define png_sizeof(x) (sizeof (x))
 
-/* The following is needed for medium model support.  It cannot be in the
- * pngpriv.h header.  Needs modification for other compilers besides
- * MSC.  Model independent support declares all arrays and pointers to be
- * large using the far keyword.  The zlib version used must also support
- * model independent data.  As of version zlib 1.0.4, the necessary changes
- * have been made in zlib.  The USE_FAR_KEYWORD define triggers other
- * changes that are needed. (Tim Wegner)
- */
+#if UINT_MAX > 4294967294
+   typedef unsigned int png_uint_32;
+#elif ULONG_MAX > 4294967294
+   typedef unsigned long int png_uint_32;
+#else
+#  error "libpng requires an unsigned 32 bit (or more) type"
+#endif
 
-/* Separate compiler dependencies (problem here is that zlib.h always
- * defines FAR. (SJT)
- */
-#ifdef __BORLANDC__
-#  if defined(__LARGE__) || defined(__HUGE__) || defined(__COMPACT__)
-#    define LDATA 1
-#  else
-#    define LDATA 0
-#  endif
-  /* GRR:  why is Cygwin in here?  Cygwin is not Borland C... */
-#  if !defined(__WIN32__) && !defined(__FLAT__) && !defined(__CYGWIN__)
-#    define PNG_MAX_MALLOC_64K /* only used in build */
-#    if (LDATA != 1)
-#      ifndef FAR
-#        define FAR __far
-#      endif
-#      define USE_FAR_KEYWORD
-#    endif   /* LDATA != 1 */
-         /* Possibly useful for moving data out of default segment.
-          * Uncomment it if you want. Could also define FARDATA as
-          * const if your compiler supports it. (SJT)
-#        define FARDATA FAR
-          */
-#  endif  /* __WIN32__, __FLAT__, __CYGWIN__ */
-#endif   /* __BORLANDC__ */
-
-
-/* Suggest testing for specific compiler first before testing for
- * FAR.  The Watcom compiler defines both __MEDIUM__ and M_I86MM,
- * making reliance oncertain keywords suspect. (SJT)
+/* Prior to 1.6.0 it was possible to disable the use of size_t, 1.6.0, however,
+ * requires an ISOC90 compiler and relies on consistent behavior of sizeof.
  */
+typedef size_t png_size_t;
+typedef ptrdiff_t png_ptrdiff_t;
 
-/* MSC Medium model */
-#ifdef FAR
-#  ifdef M_I86MM
-#    define USE_FAR_KEYWORD
-#    define FARDATA FAR
-#    include <dos.h>
+/* libpng needs to know the maximum value of 'size_t' and this controls the
+ * definition of png_alloc_size_t, below.  This maximum value of size_t limits
+ * but does not control the maximum allocations the library makes - there is
+ * direct application control of this through png_set_user_limits().
+ */
+#ifndef PNG_SMALL_SIZE_T
+   /* Compiler specific tests for systems where size_t is known to be less than
+    * 32 bits (some of these systems may no longer work because of the lack of
+    * 'far' support; see above.)
+    */
+#  if (defined(__TURBOC__) && !defined(__FLAT__)) ||\
+   (defined(_MSC_VER) && defined(MAXSEG_64K))
+#     define PNG_SMALL_SIZE_T
 #  endif
 #endif
 
-/* SJT: default case */
-#ifndef FAR
-#  define FAR
+/* png_alloc_size_t is guaranteed to be no smaller than png_size_t, and no
+ * smaller than png_uint_32.  Casts from png_size_t or png_uint_32 to
+ * png_alloc_size_t are not necessary; in fact, it is recommended not to use
+ * them at all so that the compiler can complain when something turns out to be
+ * problematic.
+ *
+ * Casts in the other direction (from png_alloc_size_t to png_size_t or
+ * png_uint_32) should be explicitly applied; however, we do not expect to
+ * encounter practical situations that require such conversions.
+ *
+ * PNG_SMALL_SIZE_T must be defined if the maximum value of size_t is less than
+ * 4294967295 - i.e. less than the maximum value of png_uint_32.
+ */
+#ifdef PNG_SMALL_SIZE_T
+   typedef png_uint_32 png_alloc_size_t;
+#else
+   typedef png_size_t png_alloc_size_t;
 #endif
 
-/* At this point FAR is always defined */
-#ifndef FARDATA
-#  define FARDATA
-#endif
+/* Prior to 1.6.0 libpng offered limited support for Microsoft C compiler
+ * implementations of Intel CPU specific support of user-mode segmented address
+ * spaces, where 16-bit pointers address more than 65536 bytes of memory using
+ * separate 'segment' registers.  The implementation requires two different
+ * types of pointer (only one of which includes the segment value.)
+ *
+ * If required this support is available in version 1.2 of libpng and may be
+ * available in versions through 1.5, although the correctness of the code has
+ * not been verified recently.
+ */
 
-/* Typedef for floating-point numbers that are converted
- * to fixed-point with a multiple of 100,000, e.g., gamma
+/* Typedef for floating-point numbers that are converted to fixed-point with a
+ * multiple of 100,000, e.g., gamma
  */
 typedef png_int_32 png_fixed_point;
 
 /* Add typedefs for pointers */
-typedef void                      FAR * png_voidp;
-typedef PNG_CONST void            FAR * png_const_voidp;
-typedef png_byte                  FAR * png_bytep;
-typedef PNG_CONST png_byte        FAR * png_const_bytep;
-typedef png_uint_32               FAR * png_uint_32p;
-typedef PNG_CONST png_uint_32     FAR * png_const_uint_32p;
-typedef png_int_32                FAR * png_int_32p;
-typedef PNG_CONST png_int_32      FAR * png_const_int_32p;
-typedef png_uint_16               FAR * png_uint_16p;
-typedef PNG_CONST png_uint_16     FAR * png_const_uint_16p;
-typedef png_int_16                FAR * png_int_16p;
-typedef PNG_CONST png_int_16      FAR * png_const_int_16p;
-typedef char                      FAR * png_charp;
-typedef PNG_CONST char            FAR * png_const_charp;
-typedef png_fixed_point           FAR * png_fixed_point_p;
-typedef PNG_CONST png_fixed_point FAR * png_const_fixed_point_p;
-typedef png_size_t                FAR * png_size_tp;
-typedef PNG_CONST png_size_t      FAR * png_const_size_tp;
+typedef void                  * png_voidp;
+typedef const void            * png_const_voidp;
+typedef png_byte              * png_bytep;
+typedef const png_byte        * png_const_bytep;
+typedef png_uint_32           * png_uint_32p;
+typedef const png_uint_32     * png_const_uint_32p;
+typedef png_int_32            * png_int_32p;
+typedef const png_int_32      * png_const_int_32p;
+typedef png_uint_16           * png_uint_16p;
+typedef const png_uint_16     * png_const_uint_16p;
+typedef png_int_16            * png_int_16p;
+typedef const png_int_16      * png_const_int_16p;
+typedef char                  * png_charp;
+typedef const char            * png_const_charp;
+typedef png_fixed_point       * png_fixed_point_p;
+typedef const png_fixed_point * png_const_fixed_point_p;
+typedef png_size_t            * png_size_tp;
+typedef const png_size_t      * png_const_size_tp;
 
 #ifdef PNG_STDIO_SUPPORTED
 typedef FILE            * png_FILE_p;
 #endif
 
 #ifdef PNG_FLOATING_POINT_SUPPORTED
-typedef double           FAR * png_doublep;
-typedef PNG_CONST double FAR * png_const_doublep;
+typedef double       * png_doublep;
+typedef const double * png_const_doublep;
 #endif
 
 /* Pointers to pointers; i.e. arrays */
-typedef png_byte        FAR * FAR * png_bytepp;
-typedef png_uint_32     FAR * FAR * png_uint_32pp;
-typedef png_int_32      FAR * FAR * png_int_32pp;
-typedef png_uint_16     FAR * FAR * png_uint_16pp;
-typedef png_int_16      FAR * FAR * png_int_16pp;
-typedef PNG_CONST char  FAR * FAR * png_const_charpp;
-typedef char            FAR * FAR * png_charpp;
-typedef png_fixed_point FAR * FAR * png_fixed_point_pp;
+typedef png_byte        * * png_bytepp;
+typedef png_uint_32     * * png_uint_32pp;
+typedef png_int_32      * * png_int_32pp;
+typedef png_uint_16     * * png_uint_16pp;
+typedef png_int_16      * * png_int_16pp;
+typedef const char      * * png_const_charpp;
+typedef char            * * png_charpp;
+typedef png_fixed_point * * png_fixed_point_pp;
 #ifdef PNG_FLOATING_POINT_SUPPORTED
-typedef double          FAR * FAR * png_doublepp;
+typedef double          * * png_doublepp;
 #endif
 
 /* Pointers to pointers to pointers; i.e., pointer to array */
-typedef char            FAR * FAR * FAR * png_charppp;
+typedef char            * * * png_charppp;
 
-/* png_alloc_size_t is guaranteed to be no smaller than png_size_t,
- * and no smaller than png_uint_32.  Casts from png_size_t or png_uint_32
- * to png_alloc_size_t are not necessary; in fact, it is recommended
- * not to use them at all so that the compiler can complain when something
- * turns out to be problematic.
- * Casts in the other direction (from png_alloc_size_t to png_size_t or
- * png_uint_32) should be explicitly applied; however, we do not expect
- * to encounter practical situations that require such conversions.
- */
-#if defined(__TURBOC__) && !defined(__FLAT__)
-   typedef unsigned long png_alloc_size_t;
-#else
-#  if defined(_MSC_VER) && defined(MAXSEG_64K)
-     typedef unsigned long    png_alloc_size_t;
-#  else
-     /* This is an attempt to detect an old Windows system where (int) is
-      * actually 16 bits, in that case png_malloc must have an argument with a
-      * bigger size to accomodate the requirements of the library.
-      */
-#    if (defined(_Windows) || defined(_WINDOWS) || defined(_WINDOWS_)) && \
-        (!defined(INT_MAX) || INT_MAX <= 0x7ffffffeL)
-       typedef DWORD         png_alloc_size_t;
-#    else
-       typedef png_size_t    png_alloc_size_t;
-#    endif
-#  endif
-#endif
+#endif /* PNG_BUILDING_SYMBOL_TABLE */
 
 #endif /* PNGCONF_H */
diff --git a/src/3rdparty/libpng/pngdebug.h b/src/3rdparty/libpng/pngdebug.h
index 4547b7d..6a01b10 100644
--- a/src/3rdparty/libpng/pngdebug.h
+++ b/src/3rdparty/libpng/pngdebug.h
@@ -1,12 +1,11 @@
 
 /* pngdebug.h - Debugging macros for libpng, also used in pngtest.c
  *
- * Copyright (c) 1998-2011 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.8 [December 19, 2013]
+ * Copyright (c) 1998-2013 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
- * Last changed in libpng 1.5.0 [January 6, 2011]
- *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
  * and license in png.h
@@ -25,7 +24,7 @@
  *   (actually ((void)0)).
  *
  *   level: level of detail of message, starting at 0.  A level 'n'
- *          message is preceded by 'n' tab characters (not implemented
+ *          message is preceded by 'n' 3-space indentations (not implemented
  *          on Microsoft compilers unless PNG_DEBUG_FILE is also
  *          defined, to allow debug DLL compilation with no standard IO).
  *   message: a printf(3) style text string.  A trailing '\n' is added
@@ -77,32 +76,29 @@
 #      endif /* PNG_DEBUG_FILE */
 
 #      if (PNG_DEBUG > 1)
-/* Note: ["%s"m PNG_STRING_NEWLINE] probably does not work on
- * non-ISO compilers
- */
 #        ifdef __STDC__
 #          ifndef png_debug
 #            define png_debug(l,m) \
        do { \
        int num_tabs=l; \
-       fprintf(PNG_DEBUG_FILE,"%s" m PNG_STRING_NEWLINE,(num_tabs==1 ? "\t" : \
-         (num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":"")))); \
+       fprintf(PNG_DEBUG_FILE,"%s" m PNG_STRING_NEWLINE,(num_tabs==1 ? "   " : \
+         (num_tabs==2 ? "      " : (num_tabs>2 ? "         " : "")))); \
        } while (0)
 #          endif
 #          ifndef png_debug1
 #            define png_debug1(l,m,p1) \
        do { \
        int num_tabs=l; \
-       fprintf(PNG_DEBUG_FILE,"%s" m PNG_STRING_NEWLINE,(num_tabs==1 ? "\t" : \
-         (num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":""))),p1); \
+       fprintf(PNG_DEBUG_FILE,"%s" m PNG_STRING_NEWLINE,(num_tabs==1 ? "   " : \
+         (num_tabs==2 ? "      " : (num_tabs>2 ? "         " : ""))),p1); \
        } while (0)
 #          endif
 #          ifndef png_debug2
 #            define png_debug2(l,m,p1,p2) \
        do { \
        int num_tabs=l; \
-       fprintf(PNG_DEBUG_FILE,"%s" m PNG_STRING_NEWLINE,(num_tabs==1 ? "\t" : \
-         (num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":""))),p1,p2); \
+       fprintf(PNG_DEBUG_FILE,"%s" m PNG_STRING_NEWLINE,(num_tabs==1 ? "   " : \
+         (num_tabs==2 ? "      " : (num_tabs>2 ? "         " : ""))),p1,p2);\
        } while (0)
 #          endif
 #        else /* __STDC __ */
diff --git a/src/3rdparty/libpng/pngerror.c b/src/3rdparty/libpng/pngerror.c
index 95002f8..0781866 100644
--- a/src/3rdparty/libpng/pngerror.c
+++ b/src/3rdparty/libpng/pngerror.c
@@ -1,8 +1,8 @@
 
 /* pngerror.c - stub functions for i/o and memory allocation
  *
- * Last changed in libpng 1.5.8 [February 1, 2011]
- * Copyright (c) 1998-2012 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.15 [November 20, 2014]
+ * Copyright (c) 1998-2014 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
@@ -20,14 +20,14 @@
 
 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
 
-static PNG_FUNCTION(void, png_default_error,PNGARG((png_structp png_ptr,
+static PNG_FUNCTION(void, png_default_error,PNGARG((png_const_structrp png_ptr,
     png_const_charp error_message)),PNG_NORETURN);
 
 #ifdef PNG_WARNINGS_SUPPORTED
 static void /* PRIVATE */
-png_default_warning PNGARG((png_structp png_ptr,
+png_default_warning PNGARG((png_const_structrp png_ptr,
    png_const_charp warning_message));
-#endif /* PNG_WARNINGS_SUPPORTED */
+#endif /* WARNINGS */
 
 /* This function is called whenever there is a fatal error.  This function
  * should not be changed.  If there is a need to handle errors differently,
@@ -36,14 +36,15 @@ png_default_warning PNGARG((png_structp png_ptr,
  */
 #ifdef PNG_ERROR_TEXT_SUPPORTED
 PNG_FUNCTION(void,PNGAPI
-png_error,(png_structp png_ptr, png_const_charp error_message),PNG_NORETURN)
+png_error,(png_const_structrp png_ptr, png_const_charp error_message),
+   PNG_NORETURN)
 {
 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
    char msg[16];
    if (png_ptr != NULL)
    {
-      if (png_ptr->flags&
-         (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT))
+      if ((png_ptr->flags &
+         (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT)) != 0
       {
          if (*error_message == PNG_LITERAL_SHARP)
          {
@@ -53,7 +54,7 @@ png_error,(png_structp png_ptr, png_const_charp error_message),PNG_NORETURN)
                if (error_message[offset] == ' ')
                   break;
 
-            if (png_ptr->flags&PNG_FLAG_STRIP_ERROR_TEXT)
+            if ((png_ptr->flags & PNG_FLAG_STRIP_ERROR_TEXT) != 0)
             {
                int i;
                for (i = 0; i < offset - 1; i++)
@@ -68,7 +69,7 @@ png_error,(png_structp png_ptr, png_const_charp error_message),PNG_NORETURN)
 
       else
       {
-         if (png_ptr->flags&PNG_FLAG_STRIP_ERROR_TEXT)
+         if ((png_ptr->flags & PNG_FLAG_STRIP_ERROR_TEXT) != 0)
          {
             msg[0] = '0';
             msg[1] = '\0';
@@ -79,7 +80,8 @@ png_error,(png_structp png_ptr, png_const_charp error_message),PNG_NORETURN)
    }
 #endif
    if (png_ptr != NULL && png_ptr->error_fn != NULL)
-      (*(png_ptr->error_fn))(png_ptr, error_message);
+      (*(png_ptr->error_fn))(png_constcast(png_structrp,png_ptr),
+          error_message);
 
    /* If the custom handler doesn't exist, or if it returns,
       use the default handler, which will not return. */
@@ -87,7 +89,7 @@ png_error,(png_structp png_ptr, png_const_charp error_message),PNG_NORETURN)
 }
 #else
 PNG_FUNCTION(void,PNGAPI
-png_err,(png_structp png_ptr),PNG_NORETURN)
+png_err,(png_const_structrp png_ptr),PNG_NORETURN)
 {
    /* Prior to 1.5.2 the error_fn received a NULL pointer, expressed
     * erroneously as '\0', instead of the empty string "".  This was
@@ -95,13 +97,13 @@ png_err,(png_structp png_ptr),PNG_NORETURN)
     * will crash in this case.
     */
    if (png_ptr != NULL && png_ptr->error_fn != NULL)
-      (*(png_ptr->error_fn))(png_ptr, "");
+      (*(png_ptr->error_fn))(png_constcast(png_structrp,png_ptr), "");
 
    /* If the custom handler doesn't exist, or if it returns,
       use the default handler, which will not return. */
    png_default_error(png_ptr, "");
 }
-#endif /* PNG_ERROR_TEXT_SUPPORTED */
+#endif /* ERROR_TEXT */
 
 /* Utility to safely appends strings to a buffer.  This never errors out so
  * error checking is not required in the caller.
@@ -150,7 +152,7 @@ png_format_number(png_const_charp start, png_charp end, int format,
          case PNG_NUMBER_FORMAT_fixed:
             /* Needs five digits (the fraction) */
             mincount = 5;
-            if (output || number % 10 != 0)
+            if (output != 0 || number % 10 != 0)
             {
                *--end = digits[number % 10];
                output = 1;
@@ -161,7 +163,7 @@ png_format_number(png_const_charp start, png_charp end, int format,
          case PNG_NUMBER_FORMAT_02u:
             /* Expects at least 2 digits. */
             mincount = 2;
-            /* fall through */
+            /* FALL THROUGH */
 
          case PNG_NUMBER_FORMAT_u:
             *--end = digits[number % 10];
@@ -171,7 +173,7 @@ png_format_number(png_const_charp start, png_charp end, int format,
          case PNG_NUMBER_FORMAT_02x:
             /* This format expects at least two digits */
             mincount = 2;
-            /* fall through */
+            /* FALL THROUGH */
 
          case PNG_NUMBER_FORMAT_x:
             *--end = digits[number & 0xf];
@@ -187,13 +189,13 @@ png_format_number(png_const_charp start, png_charp end, int format,
       ++count;
 
       /* Float a fixed number here: */
-      if (format == PNG_NUMBER_FORMAT_fixed) if (count == 5) if (end > start)
+      if ((format == PNG_NUMBER_FORMAT_fixed) && (count == 5) && (end > start))
       {
          /* End of the fraction, but maybe nothing was output?  In that case
           * drop the decimal point.  If the number is a true zero handle that
           * here.
           */
-         if (output)
+         if (output != 0)
             *--end = '.';
          else if (number == 0) /* and !output */
             *--end = '0';
@@ -211,14 +213,14 @@ png_format_number(png_const_charp start, png_charp end, int format,
  * png_set_error_fn() to replace the warning function at run-time.
  */
 void PNGAPI
-png_warning(png_structp png_ptr, png_const_charp warning_message)
+png_warning(png_const_structrp png_ptr, png_const_charp warning_message)
 {
    int offset = 0;
    if (png_ptr != NULL)
    {
 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
-   if (png_ptr->flags&
-       (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT))
+   if ((png_ptr->flags &
+       (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT)) != 0)
 #endif
       {
          if (*warning_message == PNG_LITERAL_SHARP)
@@ -230,7 +232,8 @@ png_warning(png_structp png_ptr, png_const_charp warning_message)
       }
    }
    if (png_ptr != NULL && png_ptr->warning_fn != NULL)
-      (*(png_ptr->warning_fn))(png_ptr, warning_message + offset);
+      (*(png_ptr->warning_fn))(png_constcast(png_structrp,png_ptr),
+         warning_message + offset);
    else
       png_default_warning(png_ptr, warning_message + offset);
 }
@@ -278,7 +281,7 @@ png_warning_parameter_signed(png_warning_parameters p, int number, int format,
 }
 
 void
-png_formatted_warning(png_structp png_ptr, png_warning_parameters p,
+png_formatted_warning(png_const_structrp png_ptr, png_warning_parameters p,
    png_const_charp message)
 {
    /* The internal buffer is just 192 bytes - enough for all our messages,
@@ -346,29 +349,79 @@ png_formatted_warning(png_structp png_ptr, png_warning_parameters p,
    /* i is always less than (sizeof msg), so: */
    msg[i] = '\0';
 
-   /* And this is the formatted message, it may be larger than
-    * PNG_MAX_ERROR_TEXT, but that is only used for 'chunk' errors and these are
-    * not (currently) formatted.
+   /* And this is the formatted message. It may be larger than
+    * PNG_MAX_ERROR_TEXT, but that is only used for 'chunk' errors and these
+    * are not (currently) formatted.
     */
    png_warning(png_ptr, msg);
 }
-#endif /* PNG_WARNINGS_SUPPORTED */
+#endif /* WARNINGS */
 
 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
 void PNGAPI
-png_benign_error(png_structp png_ptr, png_const_charp error_message)
+png_benign_error(png_const_structrp png_ptr, png_const_charp error_message)
 {
-  if (png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN)
+   if ((png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN) != 0)
+   {
+#     ifdef PNG_READ_SUPPORTED
+         if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
+            png_ptr->chunk_name != 0)
+            png_chunk_warning(png_ptr, error_message);
+         else
+#     endif
+      png_warning(png_ptr, error_message);
+   }
+
+   else
+   {
+#     ifdef PNG_READ_SUPPORTED
+         if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
+            png_ptr->chunk_name != 0)
+            png_chunk_error(png_ptr, error_message);
+         else
+#     endif
+      png_error(png_ptr, error_message);
+   }
+
+#  ifndef PNG_ERROR_TEXT_SUPPORTED
+      PNG_UNUSED(error_message)
+#  endif
+}
+
+void /* PRIVATE */
+png_app_warning(png_const_structrp png_ptr, png_const_charp error_message)
+{
+  if ((png_ptr->flags & PNG_FLAG_APP_WARNINGS_WARN) != 0)
      png_warning(png_ptr, error_message);
   else
      png_error(png_ptr, error_message);
+
+#  ifndef PNG_ERROR_TEXT_SUPPORTED
+      PNG_UNUSED(error_message)
+#  endif
 }
-#endif
 
+void /* PRIVATE */
+png_app_error(png_const_structrp png_ptr, png_const_charp error_message)
+{
+  if ((png_ptr->flags & PNG_FLAG_APP_ERRORS_WARN) != 0)
+     png_warning(png_ptr, error_message);
+  else
+     png_error(png_ptr, error_message);
+
+#  ifndef PNG_ERROR_TEXT_SUPPORTED
+      PNG_UNUSED(error_message)
+#  endif
+}
+#endif /* BENIGN_ERRORS */
+
+#define PNG_MAX_ERROR_TEXT 196 /* Currently limited by profile_error in png.c */
+#if defined(PNG_WARNINGS_SUPPORTED) || \
+   (defined(PNG_READ_SUPPORTED) && defined(PNG_ERROR_TEXT_SUPPORTED))
 /* These utilities are used internally to build an error message that relates
  * to the current chunk.  The chunk name comes from png_ptr->chunk_name,
- * this is used to prefix the message.  The message is limited in length
- * to 63 bytes, the name characters are output as hex digits wrapped in []
+ * which is used to prefix the message.  The message is limited in length
+ * to 63 bytes. The name characters are output as hex digits wrapped in []
  * if the character is invalid.
  */
 #define isnonalpha(c) ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
@@ -377,10 +430,8 @@ static PNG_CONST char png_digit[16] = {
    'A', 'B', 'C', 'D', 'E', 'F'
 };
 
-#define PNG_MAX_ERROR_TEXT 64
-#if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_ERROR_TEXT_SUPPORTED)
 static void /* PRIVATE */
-png_format_buffer(png_structp png_ptr, png_charp buffer, png_const_charp
+png_format_buffer(png_const_structrp png_ptr, png_charp buffer, png_const_charp
     error_message)
 {
    png_uint_32 chunk_name = png_ptr->chunk_name;
@@ -391,7 +442,7 @@ png_format_buffer(png_structp png_ptr, png_charp buffer, png_const_charp
       int c = (int)(chunk_name >> ishift) & 0xff;
 
       ishift -= 8;
-      if (isnonalpha(c))
+      if (isnonalpha(c) != 0)
       {
          buffer[iout++] = PNG_LITERAL_LEFT_SQUARE_BRACKET;
          buffer[iout++] = png_digit[(c & 0xf0) >> 4];
@@ -422,11 +473,11 @@ png_format_buffer(png_structp png_ptr, png_charp buffer, png_const_charp
       buffer[iout] = '\0';
    }
 }
-#endif /* PNG_WARNINGS_SUPPORTED || PNG_ERROR_TEXT_SUPPORTED */
+#endif /* WARNINGS || ERROR_TEXT */
 
 #if defined(PNG_READ_SUPPORTED) && defined(PNG_ERROR_TEXT_SUPPORTED)
 PNG_FUNCTION(void,PNGAPI
-png_chunk_error,(png_structp png_ptr, png_const_charp error_message),
+png_chunk_error,(png_const_structrp png_ptr, png_const_charp error_message),
    PNG_NORETURN)
 {
    char msg[18+PNG_MAX_ERROR_TEXT];
@@ -439,11 +490,11 @@ png_chunk_error,(png_structp png_ptr, png_const_charp error_message),
       png_error(png_ptr, msg);
    }
 }
-#endif /* PNG_READ_SUPPORTED && PNG_ERROR_TEXT_SUPPORTED */
+#endif /* READ && ERROR_TEXT */
 
 #ifdef PNG_WARNINGS_SUPPORTED
 void PNGAPI
-png_chunk_warning(png_structp png_ptr, png_const_charp warning_message)
+png_chunk_warning(png_const_structrp png_ptr, png_const_charp warning_message)
 {
    char msg[18+PNG_MAX_ERROR_TEXT];
    if (png_ptr == NULL)
@@ -455,38 +506,83 @@ png_chunk_warning(png_structp png_ptr, png_const_charp warning_message)
       png_warning(png_ptr, msg);
    }
 }
-#endif /* PNG_WARNINGS_SUPPORTED */
+#endif /* WARNINGS */
 
 #ifdef PNG_READ_SUPPORTED
 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
 void PNGAPI
-png_chunk_benign_error(png_structp png_ptr, png_const_charp error_message)
+png_chunk_benign_error(png_const_structrp png_ptr, png_const_charp
+    error_message)
 {
-   if (png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN)
+   if ((png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN) != 0)
       png_chunk_warning(png_ptr, error_message);
 
    else
       png_chunk_error(png_ptr, error_message);
+
+#  ifndef PNG_ERROR_TEXT_SUPPORTED
+      PNG_UNUSED(error_message)
+#  endif
 }
 #endif
-#endif /* PNG_READ_SUPPORTED */
+#endif /* READ */
+
+void /* PRIVATE */
+png_chunk_report(png_const_structrp png_ptr, png_const_charp message, int error)
+{
+#  ifndef PNG_WARNINGS_SUPPORTED
+      PNG_UNUSED(message)
+#  endif
+
+   /* This is always supported, but for just read or just write it
+    * unconditionally does the right thing.
+    */
+#  if defined(PNG_READ_SUPPORTED) && defined(PNG_WRITE_SUPPORTED)
+      if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
+#  endif
+
+#  ifdef PNG_READ_SUPPORTED
+      {
+         if (error < PNG_CHUNK_ERROR)
+            png_chunk_warning(png_ptr, message);
+
+         else
+            png_chunk_benign_error(png_ptr, message);
+      }
+#  endif
+
+#  if defined(PNG_READ_SUPPORTED) && defined(PNG_WRITE_SUPPORTED)
+      else if ((png_ptr->mode & PNG_IS_READ_STRUCT) == 0)
+#  endif
+
+#  ifdef PNG_WRITE_SUPPORTED
+      {
+         if (error < PNG_CHUNK_WRITE_ERROR)
+            png_app_warning(png_ptr, message);
+
+         else
+            png_app_error(png_ptr, message);
+      }
+#  endif
+}
 
 #ifdef PNG_ERROR_TEXT_SUPPORTED
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 PNG_FUNCTION(void,
-png_fixed_error,(png_structp png_ptr, png_const_charp name),PNG_NORETURN)
+png_fixed_error,(png_const_structrp png_ptr, png_const_charp name),PNG_NORETURN)
 {
 #  define fixed_message "fixed point overflow in "
 #  define fixed_message_ln ((sizeof fixed_message)-1)
    int  iin;
    char msg[fixed_message_ln+PNG_MAX_ERROR_TEXT];
-   png_memcpy(msg, fixed_message, fixed_message_ln);
+   memcpy(msg, fixed_message, fixed_message_ln);
    iin = 0;
-   if (name != NULL) while (iin < (PNG_MAX_ERROR_TEXT-1) && name[iin] != 0)
-   {
-      msg[fixed_message_ln + iin] = name[iin];
-      ++iin;
-   }
+   if (name != NULL)
+      while (iin < (PNG_MAX_ERROR_TEXT-1) && name[iin] != 0)
+      {
+         msg[fixed_message_ln + iin] = name[iin];
+         ++iin;
+      }
    msg[fixed_message_ln + iin] = 0;
    png_error(png_ptr, msg);
 }
@@ -498,14 +594,111 @@ png_fixed_error,(png_structp png_ptr, png_const_charp name),PNG_NORETURN)
  * otherwise it is necessary for png_default_error to be overridden.
  */
 jmp_buf* PNGAPI
-png_set_longjmp_fn(png_structp png_ptr, png_longjmp_ptr longjmp_fn,
+png_set_longjmp_fn(png_structrp png_ptr, png_longjmp_ptr longjmp_fn,
     size_t jmp_buf_size)
 {
-   if (png_ptr == NULL || jmp_buf_size != png_sizeof(jmp_buf))
+   /* From libpng 1.6.0 the app gets one chance to set a 'jmpbuf_size' value
+    * and it must not change after that.  Libpng doesn't care how big the
+    * buffer is, just that it doesn't change.
+    *
+    * If the buffer size is no *larger* than the size of jmp_buf when libpng is
+    * compiled a built in jmp_buf is returned; this preserves the pre-1.6.0
+    * semantics that this call will not fail.  If the size is larger, however,
+    * the buffer is allocated and this may fail, causing the function to return
+    * NULL.
+    */
+   if (png_ptr == NULL)
       return NULL;
 
+   if (png_ptr->jmp_buf_ptr == NULL)
+   {
+      png_ptr->jmp_buf_size = 0; /* not allocated */
+
+      if (jmp_buf_size <= (sizeof png_ptr->jmp_buf_local))
+         png_ptr->jmp_buf_ptr = &png_ptr->jmp_buf_local;
+
+      else
+      {
+         png_ptr->jmp_buf_ptr = png_voidcast(jmp_buf *,
+            png_malloc_warn(png_ptr, jmp_buf_size));
+
+         if (png_ptr->jmp_buf_ptr == NULL)
+            return NULL; /* new NULL return on OOM */
+
+         png_ptr->jmp_buf_size = jmp_buf_size;
+      }
+   }
+
+   else /* Already allocated: check the size */
+   {
+      size_t size = png_ptr->jmp_buf_size;
+
+      if (size == 0)
+      {
+         size = (sizeof png_ptr->jmp_buf_local);
+         if (png_ptr->jmp_buf_ptr != &png_ptr->jmp_buf_local)
+         {
+            /* This is an internal error in libpng: somehow we have been left
+             * with a stack allocated jmp_buf when the application regained
+             * control.  It's always possible to fix this up, but for the moment
+             * this is a png_error because that makes it easy to detect.
+             */
+            png_error(png_ptr, "Libpng jmp_buf still allocated");
+            /* png_ptr->jmp_buf_ptr = &png_ptr->jmp_buf_local; */
+         }
+      }
+
+      if (size != jmp_buf_size)
+      {
+         png_warning(png_ptr, "Application jmp_buf size changed");
+         return NULL; /* caller will probably crash: no choice here */
+      }
+   }
+
+   /* Finally fill in the function, now we have a satisfactory buffer. It is
+    * valid to change the function on every call.
+    */
    png_ptr->longjmp_fn = longjmp_fn;
-   return &png_ptr->longjmp_buffer;
+   return png_ptr->jmp_buf_ptr;
+}
+
+void /* PRIVATE */
+png_free_jmpbuf(png_structrp png_ptr)
+{
+   if (png_ptr != NULL)
+   {
+      jmp_buf *jb = png_ptr->jmp_buf_ptr;
+
+      /* A size of 0 is used to indicate a local, stack, allocation of the
+       * pointer; used here and in png.c
+       */
+      if (jb != NULL && png_ptr->jmp_buf_size > 0)
+      {
+
+         /* This stuff is so that a failure to free the error control structure
+          * does not leave libpng in a state with no valid error handling: the
+          * free always succeeds, if there is an error it gets ignored.
+          */
+         if (jb != &png_ptr->jmp_buf_local)
+         {
+            /* Make an internal, libpng, jmp_buf to return here */
+            jmp_buf free_jmp_buf;
+
+            if (!setjmp(free_jmp_buf))
+            {
+               png_ptr->jmp_buf_ptr = &free_jmp_buf; /* come back here */
+               png_ptr->jmp_buf_size = 0; /* stack allocation */
+               png_ptr->longjmp_fn = longjmp;
+               png_free(png_ptr, jb); /* Return to setjmp on error */
+            }
+         }
+      }
+
+      /* *Always* cancel everything out: */
+      png_ptr->jmp_buf_size = 0;
+      png_ptr->jmp_buf_ptr = NULL;
+      png_ptr->longjmp_fn = 0;
+   }
 }
 #endif
 
@@ -515,7 +708,7 @@ png_set_longjmp_fn(png_structp png_ptr, png_longjmp_ptr longjmp_fn,
  * error function pointer in png_set_error_fn().
  */
 static PNG_FUNCTION(void /* PRIVATE */,
-png_default_error,(png_structp png_ptr, png_const_charp error_message),
+png_default_error,(png_const_structrp png_ptr, png_const_charp error_message),
    PNG_NORETURN)
 {
 #ifdef PNG_CONSOLE_IO_SUPPORTED
@@ -562,24 +755,23 @@ png_default_error,(png_structp png_ptr, png_const_charp error_message),
 }
 
 PNG_FUNCTION(void,PNGAPI
-png_longjmp,(png_structp png_ptr, int val),PNG_NORETURN)
+png_longjmp,(png_const_structrp png_ptr, int val),PNG_NORETURN)
 {
 #ifdef PNG_SETJMP_SUPPORTED
-   if (png_ptr && png_ptr->longjmp_fn)
-   {
-#  ifdef USE_FAR_KEYWORD
-      {
-         jmp_buf tmp_jmpbuf;
-         png_memcpy(tmp_jmpbuf, png_ptr->longjmp_buffer, png_sizeof(jmp_buf));
-         png_ptr->longjmp_fn(tmp_jmpbuf, val);
-      }
-
-#  else
-   png_ptr->longjmp_fn(png_ptr->longjmp_buffer, val);
-#  endif
-   }
+   if (png_ptr != NULL && png_ptr->longjmp_fn != NULL &&
+       png_ptr->jmp_buf_ptr != NULL)
+      png_ptr->longjmp_fn(*png_ptr->jmp_buf_ptr, val);
+#else
+   PNG_UNUSED(png_ptr)
+   PNG_UNUSED(val)
 #endif
-   /* Here if not setjmp support or if png_ptr is null. */
+
+   /* If control reaches this point, png_longjmp() must not return. The only
+    * choice is to terminate the whole process (or maybe the thread); to do
+    * this the ANSI-C abort() function is used unless a different method is 
+    * implemented by overriding the default configuration setting for
+    * PNG_ABORT().
+    */
    PNG_ABORT();
 }
 
@@ -590,7 +782,7 @@ png_longjmp,(png_structp png_ptr, int val),PNG_NORETURN)
  * not used, but it is passed in case it may be useful.
  */
 static void /* PRIVATE */
-png_default_warning(png_structp png_ptr, png_const_charp warning_message)
+png_default_warning(png_const_structrp png_ptr, png_const_charp warning_message)
 {
 #ifdef PNG_CONSOLE_IO_SUPPORTED
 #  ifdef PNG_ERROR_NUMBERS_SUPPORTED
@@ -632,15 +824,15 @@ png_default_warning(png_structp png_ptr, png_const_charp warning_message)
 #endif
    PNG_UNUSED(png_ptr) /* Make compiler happy */
 }
-#endif /* PNG_WARNINGS_SUPPORTED */
+#endif /* WARNINGS */
 
 /* This function is called when the application wants to use another method
  * of handling errors and warnings.  Note that the error function MUST NOT
  * return to the calling routine or serious problems will occur.  The return
- * method used in the default routine calls longjmp(png_ptr->longjmp_buffer, 1)
+ * method used in the default routine calls longjmp(png_ptr->jmp_buf_ptr, 1)
  */
 void PNGAPI
-png_set_error_fn(png_structp png_ptr, png_voidp error_ptr,
+png_set_error_fn(png_structrp png_ptr, png_voidp error_ptr,
     png_error_ptr error_fn, png_error_ptr warning_fn)
 {
    if (png_ptr == NULL)
@@ -661,7 +853,7 @@ png_set_error_fn(png_structp png_ptr, png_voidp error_ptr,
  * pointer before png_write_destroy and png_read_destroy are called.
  */
 png_voidp PNGAPI
-png_get_error_ptr(png_const_structp png_ptr)
+png_get_error_ptr(png_const_structrp png_ptr)
 {
    if (png_ptr == NULL)
       return NULL;
@@ -672,7 +864,7 @@ png_get_error_ptr(png_const_structp png_ptr)
 
 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
 void PNGAPI
-png_set_strip_error_numbers(png_structp png_ptr, png_uint_32 strip_mode)
+png_set_strip_error_numbers(png_structrp png_ptr, png_uint_32 strip_mode)
 {
    if (png_ptr != NULL)
    {
@@ -682,4 +874,90 @@ png_set_strip_error_numbers(png_structp png_ptr, png_uint_32 strip_mode)
    }
 }
 #endif
-#endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */
+
+#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
+   defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
+   /* Currently the above both depend on SETJMP_SUPPORTED, however it would be
+    * possible to implement without setjmp support just so long as there is some
+    * way to handle the error return here:
+    */
+PNG_FUNCTION(void /* PRIVATE */, (PNGCBAPI
+png_safe_error),(png_structp png_nonconst_ptr, png_const_charp error_message),
+   PNG_NORETURN)
+{
+   const png_const_structrp png_ptr = png_nonconst_ptr;
+   png_imagep image = png_voidcast(png_imagep, png_ptr->error_ptr);
+
+   /* An error is always logged here, overwriting anything (typically a warning)
+    * that is already there:
+    */
+   if (image != NULL)
+   {
+      png_safecat(image->message, (sizeof image->message), 0, error_message);
+      image->warning_or_error |= PNG_IMAGE_ERROR;
+
+      /* Retrieve the jmp_buf from within the png_control, making this work for
+       * C++ compilation too is pretty tricky: C++ wants a pointer to the first
+       * element of a jmp_buf, but C doesn't tell us the type of that.
+       */
+      if (image->opaque != NULL && image->opaque->error_buf != NULL)
+         longjmp(png_control_jmp_buf(image->opaque), 1);
+
+      /* Missing longjmp buffer, the following is to help debugging: */
+      {
+         size_t pos = png_safecat(image->message, (sizeof image->message), 0,
+            "bad longjmp: ");
+         png_safecat(image->message, (sizeof image->message), pos,
+             error_message);
+      }
+   }
+
+   /* Here on an internal programming error. */
+   abort();
+}
+
+#ifdef PNG_WARNINGS_SUPPORTED
+void /* PRIVATE */ PNGCBAPI
+png_safe_warning(png_structp png_nonconst_ptr, png_const_charp warning_message)
+{
+   const png_const_structrp png_ptr = png_nonconst_ptr;
+   png_imagep image = png_voidcast(png_imagep, png_ptr->error_ptr);
+
+   /* A warning is only logged if there is no prior warning or error. */
+   if (image->warning_or_error == 0)
+   {
+      png_safecat(image->message, (sizeof image->message), 0, warning_message);
+      image->warning_or_error |= PNG_IMAGE_WARNING;
+   }
+}
+#endif
+
+int /* PRIVATE */
+png_safe_execute(png_imagep image_in, int (*function)(png_voidp), png_voidp arg)
+{
+   volatile png_imagep image = image_in;
+   volatile int result;
+   volatile png_voidp saved_error_buf;
+   jmp_buf safe_jmpbuf;
+
+   /* Safely execute function(arg) with png_error returning to this function. */
+   saved_error_buf = image->opaque->error_buf;
+   result = setjmp(safe_jmpbuf) == 0;
+
+   if (result != 0)
+   {
+
+      image->opaque->error_buf = safe_jmpbuf;
+      result = function(arg);
+   }
+
+   image->opaque->error_buf = saved_error_buf;
+
+   /* And do the cleanup prior to any failure return. */
+   if (result == 0)
+      png_image_free(image);
+
+   return result;
+}
+#endif /* SIMPLIFIED READ || SIMPLIFIED_WRITE */
+#endif /* READ || WRITE */
diff --git a/src/3rdparty/libpng/pngget.c b/src/3rdparty/libpng/pngget.c
index 43400cd..743a6a9 100644
--- a/src/3rdparty/libpng/pngget.c
+++ b/src/3rdparty/libpng/pngget.c
@@ -1,8 +1,8 @@
 
 /* pngget.c - retrieval of values from info struct
  *
- * Last changed in libpng 1.5.7 [December 15, 2011]
- * Copyright (c) 1998-2011 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.17 [March 26, 2015]
+ * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
@@ -17,7 +17,7 @@
 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
 
 png_uint_32 PNGAPI
-png_get_valid(png_const_structp png_ptr, png_const_infop info_ptr,
+png_get_valid(png_const_structrp png_ptr, png_const_inforp info_ptr,
     png_uint_32 flag)
 {
    if (png_ptr != NULL && info_ptr != NULL)
@@ -27,7 +27,7 @@ png_get_valid(png_const_structp png_ptr, png_const_infop info_ptr,
 }
 
 png_size_t PNGAPI
-png_get_rowbytes(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_rowbytes(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return(info_ptr->rowbytes);
@@ -37,7 +37,7 @@ png_get_rowbytes(png_const_structp png_ptr, png_const_infop info_ptr)
 
 #ifdef PNG_INFO_IMAGE_SUPPORTED
 png_bytepp PNGAPI
-png_get_rows(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_rows(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return(info_ptr->row_pointers);
@@ -49,7 +49,7 @@ png_get_rows(png_const_structp png_ptr, png_const_infop info_ptr)
 #ifdef PNG_EASY_ACCESS_SUPPORTED
 /* Easy access to info, added in libpng-0.99 */
 png_uint_32 PNGAPI
-png_get_image_width(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_image_width(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return info_ptr->width;
@@ -58,7 +58,7 @@ png_get_image_width(png_const_structp png_ptr, png_const_infop info_ptr)
 }
 
 png_uint_32 PNGAPI
-png_get_image_height(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_image_height(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return info_ptr->height;
@@ -67,7 +67,7 @@ png_get_image_height(png_const_structp png_ptr, png_const_infop info_ptr)
 }
 
 png_byte PNGAPI
-png_get_bit_depth(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_bit_depth(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return info_ptr->bit_depth;
@@ -76,7 +76,7 @@ png_get_bit_depth(png_const_structp png_ptr, png_const_infop info_ptr)
 }
 
 png_byte PNGAPI
-png_get_color_type(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_color_type(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return info_ptr->color_type;
@@ -85,7 +85,7 @@ png_get_color_type(png_const_structp png_ptr, png_const_infop info_ptr)
 }
 
 png_byte PNGAPI
-png_get_filter_type(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_filter_type(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return info_ptr->filter_type;
@@ -94,7 +94,7 @@ png_get_filter_type(png_const_structp png_ptr, png_const_infop info_ptr)
 }
 
 png_byte PNGAPI
-png_get_interlace_type(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_interlace_type(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return info_ptr->interlace_type;
@@ -103,7 +103,7 @@ png_get_interlace_type(png_const_structp png_ptr, png_const_infop info_ptr)
 }
 
 png_byte PNGAPI
-png_get_compression_type(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_compression_type(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return info_ptr->compression_type;
@@ -112,10 +112,12 @@ png_get_compression_type(png_const_structp png_ptr, png_const_infop info_ptr)
 }
 
 png_uint_32 PNGAPI
-png_get_x_pixels_per_meter(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_x_pixels_per_meter(png_const_structrp png_ptr, png_const_inforp
+   info_ptr)
 {
 #ifdef PNG_pHYs_SUPPORTED
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_pHYs) != 0)
       {
          png_debug1(1, "in %s retrieval function",
              "png_get_x_pixels_per_meter");
@@ -123,16 +125,21 @@ png_get_x_pixels_per_meter(png_const_structp png_ptr, png_const_infop info_ptr)
          if (info_ptr->phys_unit_type == PNG_RESOLUTION_METER)
             return (info_ptr->x_pixels_per_unit);
       }
+#else
+   PNG_UNUSED(png_ptr)
+   PNG_UNUSED(info_ptr)
 #endif
 
    return (0);
 }
 
 png_uint_32 PNGAPI
-png_get_y_pixels_per_meter(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_y_pixels_per_meter(png_const_structrp png_ptr, png_const_inforp
+    info_ptr)
 {
 #ifdef PNG_pHYs_SUPPORTED
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_pHYs) != 0)
    {
       png_debug1(1, "in %s retrieval function",
           "png_get_y_pixels_per_meter");
@@ -140,16 +147,20 @@ png_get_y_pixels_per_meter(png_const_structp png_ptr, png_const_infop info_ptr)
       if (info_ptr->phys_unit_type == PNG_RESOLUTION_METER)
          return (info_ptr->y_pixels_per_unit);
    }
+#else
+   PNG_UNUSED(png_ptr)
+   PNG_UNUSED(info_ptr)
 #endif
 
    return (0);
 }
 
 png_uint_32 PNGAPI
-png_get_pixels_per_meter(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_pixels_per_meter(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
 #ifdef PNG_pHYs_SUPPORTED
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_pHYs) != 0)
    {
       png_debug1(1, "in %s retrieval function", "png_get_pixels_per_meter");
 
@@ -157,6 +168,9 @@ png_get_pixels_per_meter(png_const_structp png_ptr, png_const_infop info_ptr)
           info_ptr->x_pixels_per_unit == info_ptr->y_pixels_per_unit)
          return (info_ptr->x_pixels_per_unit);
    }
+#else
+   PNG_UNUSED(png_ptr)
+   PNG_UNUSED(info_ptr)
 #endif
 
    return (0);
@@ -164,10 +178,12 @@ png_get_pixels_per_meter(png_const_structp png_ptr, png_const_infop info_ptr)
 
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 float PNGAPI
-png_get_pixel_aspect_ratio(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_pixel_aspect_ratio(png_const_structrp png_ptr, png_const_inforp
+   info_ptr)
 {
 #ifdef PNG_READ_pHYs_SUPPORTED
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_pHYs) != 0)
    {
       png_debug1(1, "in %s retrieval function", "png_get_aspect_ratio");
 
@@ -175,6 +191,9 @@ png_get_pixel_aspect_ratio(png_const_structp png_ptr, png_const_infop info_ptr)
          return ((float)((float)info_ptr->y_pixels_per_unit
              /(float)info_ptr->x_pixels_per_unit));
    }
+#else
+   PNG_UNUSED(png_ptr)
+   PNG_UNUSED(info_ptr)
 #endif
 
    return ((float)0.0);
@@ -183,14 +202,15 @@ png_get_pixel_aspect_ratio(png_const_structp png_ptr, png_const_infop info_ptr)
 
 #ifdef PNG_FIXED_POINT_SUPPORTED
 png_fixed_point PNGAPI
-png_get_pixel_aspect_ratio_fixed(png_const_structp png_ptr,
-    png_const_infop info_ptr)
+png_get_pixel_aspect_ratio_fixed(png_const_structrp png_ptr,
+    png_const_inforp info_ptr)
 {
 #ifdef PNG_READ_pHYs_SUPPORTED
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs)
-       && info_ptr->x_pixels_per_unit > 0 && info_ptr->y_pixels_per_unit > 0
-       && info_ptr->x_pixels_per_unit <= PNG_UINT_31_MAX
-       && info_ptr->y_pixels_per_unit <= PNG_UINT_31_MAX)
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_pHYs) != 0 &&
+       info_ptr->x_pixels_per_unit > 0 && info_ptr->y_pixels_per_unit > 0 &&
+       info_ptr->x_pixels_per_unit <= PNG_UINT_31_MAX &&
+       info_ptr->y_pixels_per_unit <= PNG_UINT_31_MAX)
    {
       png_fixed_point res;
 
@@ -200,9 +220,12 @@ png_get_pixel_aspect_ratio_fixed(png_const_structp png_ptr,
        * range of 0..2^31-1; otherwise the cast might overflow.
        */
       if (png_muldiv(&res, (png_int_32)info_ptr->y_pixels_per_unit, PNG_FP_1,
-          (png_int_32)info_ptr->x_pixels_per_unit))
+          (png_int_32)info_ptr->x_pixels_per_unit) != 0)
          return res;
    }
+#else
+   PNG_UNUSED(png_ptr)
+   PNG_UNUSED(info_ptr)
 #endif
 
    return 0;
@@ -210,64 +233,80 @@ png_get_pixel_aspect_ratio_fixed(png_const_structp png_ptr,
 #endif
 
 png_int_32 PNGAPI
-png_get_x_offset_microns(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_x_offset_microns(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
 #ifdef PNG_oFFs_SUPPORTED
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_oFFs) != 0)
    {
       png_debug1(1, "in %s retrieval function", "png_get_x_offset_microns");
 
       if (info_ptr->offset_unit_type == PNG_OFFSET_MICROMETER)
          return (info_ptr->x_offset);
    }
+#else
+   PNG_UNUSED(png_ptr)
+   PNG_UNUSED(info_ptr)
 #endif
 
    return (0);
 }
 
 png_int_32 PNGAPI
-png_get_y_offset_microns(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_y_offset_microns(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
 #ifdef PNG_oFFs_SUPPORTED
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_oFFs) != 0)
    {
       png_debug1(1, "in %s retrieval function", "png_get_y_offset_microns");
 
       if (info_ptr->offset_unit_type == PNG_OFFSET_MICROMETER)
          return (info_ptr->y_offset);
    }
+#else
+   PNG_UNUSED(png_ptr)
+   PNG_UNUSED(info_ptr)
 #endif
 
    return (0);
 }
 
 png_int_32 PNGAPI
-png_get_x_offset_pixels(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_x_offset_pixels(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
 #ifdef PNG_oFFs_SUPPORTED
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_oFFs) != 0)
    {
       png_debug1(1, "in %s retrieval function", "png_get_x_offset_pixels");
 
       if (info_ptr->offset_unit_type == PNG_OFFSET_PIXEL)
          return (info_ptr->x_offset);
    }
+#else
+   PNG_UNUSED(png_ptr)
+   PNG_UNUSED(info_ptr)
 #endif
 
    return (0);
 }
 
 png_int_32 PNGAPI
-png_get_y_offset_pixels(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_y_offset_pixels(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
 #ifdef PNG_oFFs_SUPPORTED
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_oFFs) != 0)
    {
       png_debug1(1, "in %s retrieval function", "png_get_y_offset_pixels");
 
       if (info_ptr->offset_unit_type == PNG_OFFSET_PIXEL)
          return (info_ptr->y_offset);
    }
+#else
+   PNG_UNUSED(png_ptr)
+   PNG_UNUSED(info_ptr)
 #endif
 
    return (0);
@@ -298,7 +337,7 @@ ppi_from_ppm(png_uint_32 ppm)
     */
    png_fixed_point result;
    if (ppm <= PNG_UINT_31_MAX && png_muldiv(&result, (png_int_32)ppm, 127,
-       5000))
+       5000) != 0)
       return result;
 
    /* Overflow. */
@@ -307,26 +346,26 @@ ppi_from_ppm(png_uint_32 ppm)
 }
 
 png_uint_32 PNGAPI
-png_get_pixels_per_inch(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_pixels_per_inch(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
    return ppi_from_ppm(png_get_pixels_per_meter(png_ptr, info_ptr));
 }
 
 png_uint_32 PNGAPI
-png_get_x_pixels_per_inch(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_x_pixels_per_inch(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
    return ppi_from_ppm(png_get_x_pixels_per_meter(png_ptr, info_ptr));
 }
 
 png_uint_32 PNGAPI
-png_get_y_pixels_per_inch(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_y_pixels_per_inch(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
    return ppi_from_ppm(png_get_y_pixels_per_meter(png_ptr, info_ptr));
 }
 
 #ifdef PNG_FIXED_POINT_SUPPORTED
 static png_fixed_point
-png_fixed_inches_from_microns(png_structp png_ptr, png_int_32 microns)
+png_fixed_inches_from_microns(png_const_structrp png_ptr, png_int_32 microns)
 {
    /* Convert from metres * 1,000,000 to inches * 100,000, meters to
     * inches is simply *(100/2.54), so we want *(10/2.54) == 500/127.
@@ -337,8 +376,8 @@ png_fixed_inches_from_microns(png_structp png_ptr, png_int_32 microns)
 }
 
 png_fixed_point PNGAPI
-png_get_x_offset_inches_fixed(png_structp png_ptr,
-    png_const_infop info_ptr)
+png_get_x_offset_inches_fixed(png_const_structrp png_ptr,
+    png_const_inforp info_ptr)
 {
    return png_fixed_inches_from_microns(png_ptr,
        png_get_x_offset_microns(png_ptr, info_ptr));
@@ -347,8 +386,8 @@ png_get_x_offset_inches_fixed(png_structp png_ptr,
 
 #ifdef PNG_FIXED_POINT_SUPPORTED
 png_fixed_point PNGAPI
-png_get_y_offset_inches_fixed(png_structp png_ptr,
-    png_const_infop info_ptr)
+png_get_y_offset_inches_fixed(png_const_structrp png_ptr,
+    png_const_inforp info_ptr)
 {
    return png_fixed_inches_from_microns(png_ptr,
        png_get_y_offset_microns(png_ptr, info_ptr));
@@ -357,7 +396,7 @@ png_get_y_offset_inches_fixed(png_structp png_ptr,
 
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 float PNGAPI
-png_get_x_offset_inches(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_x_offset_inches(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
    /* To avoid the overflow do the conversion directly in floating
     * point.
@@ -368,7 +407,7 @@ png_get_x_offset_inches(png_const_structp png_ptr, png_const_infop info_ptr)
 
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 float PNGAPI
-png_get_y_offset_inches(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_y_offset_inches(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
    /* To avoid the overflow do the conversion directly in floating
     * point.
@@ -379,12 +418,13 @@ png_get_y_offset_inches(png_const_structp png_ptr, png_const_infop info_ptr)
 
 #ifdef PNG_pHYs_SUPPORTED
 png_uint_32 PNGAPI
-png_get_pHYs_dpi(png_const_structp png_ptr, png_const_infop info_ptr,
+png_get_pHYs_dpi(png_const_structrp png_ptr, png_const_inforp info_ptr,
     png_uint_32 *res_x, png_uint_32 *res_y, int *unit_type)
 {
    png_uint_32 retval = 0;
 
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_pHYs) != 0)
    {
       png_debug1(1, "in %s retrieval function", "pHYs");
 
@@ -415,15 +455,16 @@ png_get_pHYs_dpi(png_const_structp png_ptr, png_const_infop info_ptr,
 
    return (retval);
 }
-#endif /* PNG_pHYs_SUPPORTED */
-#endif  /* PNG_INCH_CONVERSIONS_SUPPORTED */
+#endif /* pHYs */
+#endif  /* INCH_CONVERSIONS */
 
 /* png_get_channels really belongs in here, too, but it's been around longer */
 
-#endif  /* PNG_EASY_ACCESS_SUPPORTED */
+#endif  /* EASY_ACCESS */
+
 
 png_byte PNGAPI
-png_get_channels(png_const_structp png_ptr, png_const_infop info_ptr)
+png_get_channels(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return(info_ptr->channels);
@@ -431,22 +472,25 @@ png_get_channels(png_const_structp png_ptr, png_const_infop info_ptr)
    return (0);
 }
 
+#ifdef PNG_READ_SUPPORTED
 png_const_bytep PNGAPI
-png_get_signature(png_const_structp png_ptr, png_infop info_ptr)
+png_get_signature(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return(info_ptr->signature);
 
    return (NULL);
 }
+#endif
 
 #ifdef PNG_bKGD_SUPPORTED
 png_uint_32 PNGAPI
-png_get_bKGD(png_const_structp png_ptr, png_infop info_ptr,
+png_get_bKGD(png_const_structrp png_ptr, png_inforp info_ptr,
    png_color_16p *background)
 {
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD)
-       && background != NULL)
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_bKGD) != 0 &&
+       background != NULL)
    {
       png_debug1(1, "in %s retrieval function", "bKGD");
 
@@ -463,87 +507,47 @@ png_get_bKGD(png_const_structp png_ptr, png_infop info_ptr,
  * same time to correct the rgb grayscale coefficient defaults obtained from the
  * cHRM chunk in 1.5.4
  */
-png_uint_32 PNGFAPI
-png_get_cHRM_XYZ_fixed(png_structp png_ptr, png_const_infop info_ptr,
-    png_fixed_point *int_red_X, png_fixed_point *int_red_Y,
-    png_fixed_point *int_red_Z, png_fixed_point *int_green_X,
-    png_fixed_point *int_green_Y, png_fixed_point *int_green_Z,
-    png_fixed_point *int_blue_X, png_fixed_point *int_blue_Y,
-    png_fixed_point *int_blue_Z)
-{
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM))
-   {
-      png_xy xy;
-      png_XYZ XYZ;
-
-      png_debug1(1, "in %s retrieval function", "cHRM_XYZ");
-
-      xy.whitex = info_ptr->x_white;
-      xy.whitey = info_ptr->y_white;
-      xy.redx = info_ptr->x_red;
-      xy.redy = info_ptr->y_red;
-      xy.greenx = info_ptr->x_green;
-      xy.greeny = info_ptr->y_green;
-      xy.bluex = info_ptr->x_blue;
-      xy.bluey = info_ptr->y_blue;
-
-      /* The *_checked function handles error reporting, so just return 0 if
-       * there is a failure here.
-       */
-      if (png_XYZ_from_xy_checked(png_ptr, &XYZ, xy))
-      {
-         if (int_red_X != NULL)
-            *int_red_X = XYZ.redX;
-         if (int_red_Y != NULL)
-            *int_red_Y = XYZ.redY;
-         if (int_red_Z != NULL)
-            *int_red_Z = XYZ.redZ;
-         if (int_green_X != NULL)
-            *int_green_X = XYZ.greenX;
-         if (int_green_Y != NULL)
-            *int_green_Y = XYZ.greenY;
-         if (int_green_Z != NULL)
-            *int_green_Z = XYZ.greenZ;
-         if (int_blue_X != NULL)
-            *int_blue_X = XYZ.blueX;
-         if (int_blue_Y != NULL)
-            *int_blue_Y = XYZ.blueY;
-         if (int_blue_Z != NULL)
-            *int_blue_Z = XYZ.blueZ;
-
-         return (PNG_INFO_cHRM);
-      }
-   }
-
-   return (0);
-}
-
 #  ifdef PNG_FLOATING_POINT_SUPPORTED
 png_uint_32 PNGAPI
-png_get_cHRM(png_const_structp png_ptr, png_const_infop info_ptr,
+png_get_cHRM(png_const_structrp png_ptr, png_const_inforp info_ptr,
     double *white_x, double *white_y, double *red_x, double *red_y,
     double *green_x, double *green_y, double *blue_x, double *blue_y)
 {
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM))
+   /* Quiet API change: this code used to only return the end points if a cHRM
+    * chunk was present, but the end points can also come from iCCP or sRGB
+    * chunks, so in 1.6.0 the png_get_ APIs return the end points regardless and
+    * the png_set_ APIs merely check that set end points are mutually
+    * consistent.
+    */
+   if (png_ptr != NULL && info_ptr != NULL &&
+      (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
    {
       png_debug1(1, "in %s retrieval function", "cHRM");
 
       if (white_x != NULL)
-         *white_x = png_float(png_ptr, info_ptr->x_white, "cHRM white X");
+         *white_x = png_float(png_ptr,
+            info_ptr->colorspace.end_points_xy.whitex, "cHRM white X");
       if (white_y != NULL)
-         *white_y = png_float(png_ptr, info_ptr->y_white, "cHRM white Y");
+         *white_y = png_float(png_ptr,
+            info_ptr->colorspace.end_points_xy.whitey, "cHRM white Y");
       if (red_x != NULL)
-         *red_x = png_float(png_ptr, info_ptr->x_red, "cHRM red X");
+         *red_x = png_float(png_ptr, info_ptr->colorspace.end_points_xy.redx,
+            "cHRM red X");
       if (red_y != NULL)
-         *red_y = png_float(png_ptr, info_ptr->y_red, "cHRM red Y");
+         *red_y = png_float(png_ptr, info_ptr->colorspace.end_points_xy.redy,
+            "cHRM red Y");
       if (green_x != NULL)
-         *green_x = png_float(png_ptr, info_ptr->x_green, "cHRM green X");
+         *green_x = png_float(png_ptr,
+            info_ptr->colorspace.end_points_xy.greenx, "cHRM green X");
       if (green_y != NULL)
-         *green_y = png_float(png_ptr, info_ptr->y_green, "cHRM green Y");
+         *green_y = png_float(png_ptr,
+            info_ptr->colorspace.end_points_xy.greeny, "cHRM green Y");
       if (blue_x != NULL)
-         *blue_x = png_float(png_ptr, info_ptr->x_blue, "cHRM blue X");
+         *blue_x = png_float(png_ptr, info_ptr->colorspace.end_points_xy.bluex,
+            "cHRM blue X");
       if (blue_y != NULL)
-         *blue_y = png_float(png_ptr, info_ptr->y_blue, "cHRM blue Y");
+         *blue_y = png_float(png_ptr, info_ptr->colorspace.end_points_xy.bluey,
+            "cHRM blue Y");
       return (PNG_INFO_cHRM);
    }
 
@@ -551,35 +555,43 @@ png_get_cHRM(png_const_structp png_ptr, png_const_infop info_ptr,
 }
 
 png_uint_32 PNGAPI
-png_get_cHRM_XYZ(png_structp png_ptr, png_const_infop info_ptr,
+png_get_cHRM_XYZ(png_const_structrp png_ptr, png_const_inforp info_ptr,
    double *red_X, double *red_Y, double *red_Z, double *green_X,
    double *green_Y, double *green_Z, double *blue_X, double *blue_Y,
    double *blue_Z)
 {
-   png_XYZ XYZ;
-
-   if (png_get_cHRM_XYZ_fixed(png_ptr, info_ptr,
-      &XYZ.redX, &XYZ.redY, &XYZ.redZ, &XYZ.greenX, &XYZ.greenY, &XYZ.greenZ,
-      &XYZ.blueX, &XYZ.blueY, &XYZ.blueZ) & PNG_INFO_cHRM)
+   if (png_ptr != NULL && info_ptr != NULL &&
+      (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
    {
+      png_debug1(1, "in %s retrieval function", "cHRM_XYZ(float)");
+
       if (red_X != NULL)
-         *red_X = png_float(png_ptr, XYZ.redX, "cHRM red X");
+         *red_X = png_float(png_ptr, info_ptr->colorspace.end_points_XYZ.red_X,
+            "cHRM red X");
       if (red_Y != NULL)
-         *red_Y = png_float(png_ptr, XYZ.redY, "cHRM red Y");
+         *red_Y = png_float(png_ptr, info_ptr->colorspace.end_points_XYZ.red_Y,
+            "cHRM red Y");
       if (red_Z != NULL)
-         *red_Z = png_float(png_ptr, XYZ.redZ, "cHRM red Z");
+         *red_Z = png_float(png_ptr, info_ptr->colorspace.end_points_XYZ.red_Z,
+            "cHRM red Z");
       if (green_X != NULL)
-         *green_X = png_float(png_ptr, XYZ.greenX, "cHRM green X");
+         *green_X = png_float(png_ptr,
+            info_ptr->colorspace.end_points_XYZ.green_X, "cHRM green X");
       if (green_Y != NULL)
-         *green_Y = png_float(png_ptr, XYZ.greenY, "cHRM green Y");
+         *green_Y = png_float(png_ptr,
+            info_ptr->colorspace.end_points_XYZ.green_Y, "cHRM green Y");
       if (green_Z != NULL)
-         *green_Z = png_float(png_ptr, XYZ.greenZ, "cHRM green Z");
+         *green_Z = png_float(png_ptr,
+            info_ptr->colorspace.end_points_XYZ.green_Z, "cHRM green Z");
       if (blue_X != NULL)
-         *blue_X = png_float(png_ptr, XYZ.blueX, "cHRM blue X");
+         *blue_X = png_float(png_ptr,
+            info_ptr->colorspace.end_points_XYZ.blue_X, "cHRM blue X");
       if (blue_Y != NULL)
-         *blue_Y = png_float(png_ptr, XYZ.blueY, "cHRM blue Y");
+         *blue_Y = png_float(png_ptr,
+            info_ptr->colorspace.end_points_XYZ.blue_Y, "cHRM blue Y");
       if (blue_Z != NULL)
-         *blue_Z = png_float(png_ptr, XYZ.blueZ, "cHRM blue Z");
+         *blue_Z = png_float(png_ptr,
+            info_ptr->colorspace.end_points_XYZ.blue_Z, "cHRM blue Z");
       return (PNG_INFO_cHRM);
    }
 
@@ -589,31 +601,69 @@ png_get_cHRM_XYZ(png_structp png_ptr, png_const_infop info_ptr,
 
 #  ifdef PNG_FIXED_POINT_SUPPORTED
 png_uint_32 PNGAPI
-png_get_cHRM_fixed(png_const_structp png_ptr, png_const_infop info_ptr,
+png_get_cHRM_XYZ_fixed(png_const_structrp png_ptr, png_const_inforp info_ptr,
+    png_fixed_point *int_red_X, png_fixed_point *int_red_Y,
+    png_fixed_point *int_red_Z, png_fixed_point *int_green_X,
+    png_fixed_point *int_green_Y, png_fixed_point *int_green_Z,
+    png_fixed_point *int_blue_X, png_fixed_point *int_blue_Y,
+    png_fixed_point *int_blue_Z)
+{
+   if (png_ptr != NULL && info_ptr != NULL &&
+      (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
+   {
+      png_debug1(1, "in %s retrieval function", "cHRM_XYZ");
+
+      if (int_red_X != NULL)
+         *int_red_X = info_ptr->colorspace.end_points_XYZ.red_X;
+      if (int_red_Y != NULL)
+         *int_red_Y = info_ptr->colorspace.end_points_XYZ.red_Y;
+      if (int_red_Z != NULL)
+         *int_red_Z = info_ptr->colorspace.end_points_XYZ.red_Z;
+      if (int_green_X != NULL)
+         *int_green_X = info_ptr->colorspace.end_points_XYZ.green_X;
+      if (int_green_Y != NULL)
+         *int_green_Y = info_ptr->colorspace.end_points_XYZ.green_Y;
+      if (int_green_Z != NULL)
+         *int_green_Z = info_ptr->colorspace.end_points_XYZ.green_Z;
+      if (int_blue_X != NULL)
+         *int_blue_X = info_ptr->colorspace.end_points_XYZ.blue_X;
+      if (int_blue_Y != NULL)
+         *int_blue_Y = info_ptr->colorspace.end_points_XYZ.blue_Y;
+      if (int_blue_Z != NULL)
+         *int_blue_Z = info_ptr->colorspace.end_points_XYZ.blue_Z;
+      return (PNG_INFO_cHRM);
+   }
+
+   return (0);
+}
+
+png_uint_32 PNGAPI
+png_get_cHRM_fixed(png_const_structrp png_ptr, png_const_inforp info_ptr,
     png_fixed_point *white_x, png_fixed_point *white_y, png_fixed_point *red_x,
     png_fixed_point *red_y, png_fixed_point *green_x, png_fixed_point *green_y,
     png_fixed_point *blue_x, png_fixed_point *blue_y)
 {
    png_debug1(1, "in %s retrieval function", "cHRM");
 
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM))
+   if (png_ptr != NULL && info_ptr != NULL &&
+      (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
    {
       if (white_x != NULL)
-         *white_x = info_ptr->x_white;
+         *white_x = info_ptr->colorspace.end_points_xy.whitex;
       if (white_y != NULL)
-         *white_y = info_ptr->y_white;
+         *white_y = info_ptr->colorspace.end_points_xy.whitey;
       if (red_x != NULL)
-         *red_x = info_ptr->x_red;
+         *red_x = info_ptr->colorspace.end_points_xy.redx;
       if (red_y != NULL)
-         *red_y = info_ptr->y_red;
+         *red_y = info_ptr->colorspace.end_points_xy.redy;
       if (green_x != NULL)
-         *green_x = info_ptr->x_green;
+         *green_x = info_ptr->colorspace.end_points_xy.greenx;
       if (green_y != NULL)
-         *green_y = info_ptr->y_green;
+         *green_y = info_ptr->colorspace.end_points_xy.greeny;
       if (blue_x != NULL)
-         *blue_x = info_ptr->x_blue;
+         *blue_x = info_ptr->colorspace.end_points_xy.bluex;
       if (blue_y != NULL)
-         *blue_y = info_ptr->y_blue;
+         *blue_y = info_ptr->colorspace.end_points_xy.bluey;
       return (PNG_INFO_cHRM);
    }
 
@@ -623,49 +673,57 @@ png_get_cHRM_fixed(png_const_structp png_ptr, png_const_infop info_ptr,
 #endif
 
 #ifdef PNG_gAMA_SUPPORTED
-png_uint_32 PNGFAPI
-png_get_gAMA_fixed(png_const_structp png_ptr, png_const_infop info_ptr,
+#  ifdef PNG_FIXED_POINT_SUPPORTED
+png_uint_32 PNGAPI
+png_get_gAMA_fixed(png_const_structrp png_ptr, png_const_inforp info_ptr,
     png_fixed_point *file_gamma)
 {
    png_debug1(1, "in %s retrieval function", "gAMA");
 
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_gAMA)
-       && file_gamma != NULL)
+   if (png_ptr != NULL && info_ptr != NULL &&
+      (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) != 0 &&
+      file_gamma != NULL)
    {
-      *file_gamma = info_ptr->gamma;
+      *file_gamma = info_ptr->colorspace.gamma;
       return (PNG_INFO_gAMA);
    }
 
    return (0);
 }
+#  endif
+
 #  ifdef PNG_FLOATING_POINT_SUPPORTED
 png_uint_32 PNGAPI
-png_get_gAMA(png_const_structp png_ptr, png_const_infop info_ptr,
+png_get_gAMA(png_const_structrp png_ptr, png_const_inforp info_ptr,
     double *file_gamma)
 {
-   png_fixed_point igamma;
-   png_uint_32 ok = png_get_gAMA_fixed(png_ptr, info_ptr, &igamma);
+   png_debug1(1, "in %s retrieval function", "gAMA(float)");
 
-   if (ok)
-      *file_gamma = png_float(png_ptr, igamma, "png_get_gAMA");
+   if (png_ptr != NULL && info_ptr != NULL &&
+      (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) != 0 &&
+      file_gamma != NULL)
+   {
+      *file_gamma = png_float(png_ptr, info_ptr->colorspace.gamma,
+         "png_get_gAMA");
+      return (PNG_INFO_gAMA);
+   }
 
-   return ok;
+   return (0);
 }
-
 #  endif
 #endif
 
 #ifdef PNG_sRGB_SUPPORTED
 png_uint_32 PNGAPI
-png_get_sRGB(png_const_structp png_ptr, png_const_infop info_ptr,
+png_get_sRGB(png_const_structrp png_ptr, png_const_inforp info_ptr,
     int *file_srgb_intent)
 {
    png_debug1(1, "in %s retrieval function", "sRGB");
 
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_sRGB)
-       && file_srgb_intent != NULL)
+   if (png_ptr != NULL && info_ptr != NULL &&
+      (info_ptr->valid & PNG_INFO_sRGB) != 0 && file_srgb_intent != NULL)
    {
-      *file_srgb_intent = (int)info_ptr->srgb_intent;
+      *file_srgb_intent = info_ptr->colorspace.rendering_intent;
       return (PNG_INFO_sRGB);
    }
 
@@ -675,23 +733,24 @@ png_get_sRGB(png_const_structp png_ptr, png_const_infop info_ptr,
 
 #ifdef PNG_iCCP_SUPPORTED
 png_uint_32 PNGAPI
-png_get_iCCP(png_const_structp png_ptr, png_const_infop info_ptr,
+png_get_iCCP(png_const_structrp png_ptr, png_inforp info_ptr,
     png_charpp name, int *compression_type,
     png_bytepp profile, png_uint_32 *proflen)
 {
    png_debug1(1, "in %s retrieval function", "iCCP");
 
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_iCCP)
-       && name != NULL && compression_type != NULL && profile != NULL &&
-		 proflen != NULL)
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_iCCP) != 0 &&
+       name != NULL && compression_type != NULL && profile != NULL &&
+           proflen != NULL)
    {
       *name = info_ptr->iccp_name;
       *profile = info_ptr->iccp_profile;
-      /* Compression_type is a dummy so the API won't have to change
-       * if we introduce multiple compression types later.
+      *proflen = png_get_uint_32(info_ptr->iccp_profile);
+      /* This is somewhat irrelevant since the profile data returned has
+       * actually been uncompressed.
        */
-      *proflen = info_ptr->iccp_proflen;
-      *compression_type = info_ptr->iccp_compression;
+      *compression_type = PNG_COMPRESSION_TYPE_BASE;
       return (PNG_INFO_iCCP);
    }
 
@@ -700,14 +759,14 @@ png_get_iCCP(png_const_structp png_ptr, png_const_infop info_ptr,
 #endif
 
 #ifdef PNG_sPLT_SUPPORTED
-png_uint_32 PNGAPI
-png_get_sPLT(png_const_structp png_ptr, png_const_infop info_ptr,
+int PNGAPI
+png_get_sPLT(png_const_structrp png_ptr, png_inforp info_ptr,
     png_sPLT_tpp spalettes)
 {
    if (png_ptr != NULL && info_ptr != NULL && spalettes != NULL)
    {
       *spalettes = info_ptr->splt_palettes;
-      return ((png_uint_32)info_ptr->splt_palettes_num);
+      return info_ptr->splt_palettes_num;
    }
 
    return (0);
@@ -716,13 +775,13 @@ png_get_sPLT(png_const_structp png_ptr, png_const_infop info_ptr,
 
 #ifdef PNG_hIST_SUPPORTED
 png_uint_32 PNGAPI
-png_get_hIST(png_const_structp png_ptr, png_const_infop info_ptr,
+png_get_hIST(png_const_structrp png_ptr, png_inforp info_ptr,
     png_uint_16p *hist)
 {
    png_debug1(1, "in %s retrieval function", "hIST");
 
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST)
-       && hist != NULL)
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_hIST) != 0 && hist != NULL)
    {
       *hist = info_ptr->hist;
       return (PNG_INFO_hIST);
@@ -733,22 +792,27 @@ png_get_hIST(png_const_structp png_ptr, png_const_infop info_ptr,
 #endif
 
 png_uint_32 PNGAPI
-png_get_IHDR(png_structp png_ptr, png_infop info_ptr,
+png_get_IHDR(png_const_structrp png_ptr, png_const_inforp info_ptr,
     png_uint_32 *width, png_uint_32 *height, int *bit_depth,
     int *color_type, int *interlace_type, int *compression_type,
     int *filter_type)
-
 {
    png_debug1(1, "in %s retrieval function", "IHDR");
 
-   if (png_ptr == NULL || info_ptr == NULL || width == NULL ||
-       height == NULL || bit_depth == NULL || color_type == NULL)
+   if (png_ptr == NULL || info_ptr == NULL)
       return (0);
 
-   *width = info_ptr->width;
-   *height = info_ptr->height;
-   *bit_depth = info_ptr->bit_depth;
-   *color_type = info_ptr->color_type;
+   if (width != NULL)
+       *width = info_ptr->width;
+
+   if (height != NULL)
+       *height = info_ptr->height;
+
+   if (bit_depth != NULL)
+       *bit_depth = info_ptr->bit_depth;
+
+   if (color_type != NULL)
+       *color_type = info_ptr->color_type;
 
    if (compression_type != NULL)
       *compression_type = info_ptr->compression_type;
@@ -764,7 +828,7 @@ png_get_IHDR(png_structp png_ptr, png_infop info_ptr,
     * application has ignored our advice not to mess with the members
     * of info_ptr directly.
     */
-   png_check_IHDR (png_ptr, info_ptr->width, info_ptr->height,
+   png_check_IHDR(png_ptr, info_ptr->width, info_ptr->height,
        info_ptr->bit_depth, info_ptr->color_type, info_ptr->interlace_type,
        info_ptr->compression_type, info_ptr->filter_type);
 
@@ -773,13 +837,14 @@ png_get_IHDR(png_structp png_ptr, png_infop info_ptr,
 
 #ifdef PNG_oFFs_SUPPORTED
 png_uint_32 PNGAPI
-png_get_oFFs(png_const_structp png_ptr, png_const_infop info_ptr,
+png_get_oFFs(png_const_structrp png_ptr, png_const_inforp info_ptr,
     png_int_32 *offset_x, png_int_32 *offset_y, int *unit_type)
 {
    png_debug1(1, "in %s retrieval function", "oFFs");
 
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs)
-       && offset_x != NULL && offset_y != NULL && unit_type != NULL)
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_oFFs) != 0 &&
+       offset_x != NULL && offset_y != NULL && unit_type != NULL)
    {
       *offset_x = info_ptr->x_offset;
       *offset_y = info_ptr->y_offset;
@@ -793,14 +858,15 @@ png_get_oFFs(png_const_structp png_ptr, png_const_infop info_ptr,
 
 #ifdef PNG_pCAL_SUPPORTED
 png_uint_32 PNGAPI
-png_get_pCAL(png_const_structp png_ptr, png_const_infop info_ptr,
+png_get_pCAL(png_const_structrp png_ptr, png_inforp info_ptr,
     png_charp *purpose, png_int_32 *X0, png_int_32 *X1, int *type, int *nparams,
     png_charp *units, png_charpp *params)
 {
    png_debug1(1, "in %s retrieval function", "pCAL");
 
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL)
-       && purpose != NULL && X0 != NULL && X1 != NULL && type != NULL &&
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_pCAL) != 0 &&
+       purpose != NULL && X0 != NULL && X1 != NULL && type != NULL &&
        nparams != NULL && units != NULL && params != NULL)
    {
       *purpose = info_ptr->pcal_purpose;
@@ -819,16 +885,20 @@ png_get_pCAL(png_const_structp png_ptr, png_const_infop info_ptr,
 
 #ifdef PNG_sCAL_SUPPORTED
 #  ifdef PNG_FIXED_POINT_SUPPORTED
-#    ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
+#    if defined(PNG_FLOATING_ARITHMETIC_SUPPORTED) || \
+         defined(PNG_FLOATING_POINT_SUPPORTED)
 png_uint_32 PNGAPI
-png_get_sCAL_fixed(png_structp png_ptr, png_const_infop info_ptr,
+png_get_sCAL_fixed(png_const_structrp png_ptr, png_const_inforp info_ptr,
     int *unit, png_fixed_point *width, png_fixed_point *height)
 {
    if (png_ptr != NULL && info_ptr != NULL &&
-       (info_ptr->valid & PNG_INFO_sCAL))
+       (info_ptr->valid & PNG_INFO_sCAL) != 0)
    {
       *unit = info_ptr->scal_unit;
-      /*TODO: make this work without FP support */
+      /*TODO: make this work without FP support; the API is currently eliminated
+       * if neither floating point APIs nor internal floating point arithmetic
+       * are enabled.
+       */
       *width = png_fixed(png_ptr, atof(info_ptr->scal_s_width), "sCAL width");
       *height = png_fixed(png_ptr, atof(info_ptr->scal_s_height),
          "sCAL height");
@@ -841,11 +911,11 @@ png_get_sCAL_fixed(png_structp png_ptr, png_const_infop info_ptr,
 #  endif /* FIXED_POINT */
 #  ifdef PNG_FLOATING_POINT_SUPPORTED
 png_uint_32 PNGAPI
-png_get_sCAL(png_const_structp png_ptr, png_const_infop info_ptr,
+png_get_sCAL(png_const_structrp png_ptr, png_const_inforp info_ptr,
     int *unit, double *width, double *height)
 {
    if (png_ptr != NULL && info_ptr != NULL &&
-       (info_ptr->valid & PNG_INFO_sCAL))
+       (info_ptr->valid & PNG_INFO_sCAL) != 0)
    {
       *unit = info_ptr->scal_unit;
       *width = atof(info_ptr->scal_s_width);
@@ -857,11 +927,11 @@ png_get_sCAL(png_const_structp png_ptr, png_const_infop info_ptr,
 }
 #  endif /* FLOATING POINT */
 png_uint_32 PNGAPI
-png_get_sCAL_s(png_const_structp png_ptr, png_const_infop info_ptr,
+png_get_sCAL_s(png_const_structrp png_ptr, png_const_inforp info_ptr,
     int *unit, png_charpp width, png_charpp height)
 {
    if (png_ptr != NULL && info_ptr != NULL &&
-       (info_ptr->valid & PNG_INFO_sCAL))
+       (info_ptr->valid & PNG_INFO_sCAL) != 0)
    {
       *unit = info_ptr->scal_unit;
       *width = info_ptr->scal_s_width;
@@ -875,7 +945,7 @@ png_get_sCAL_s(png_const_structp png_ptr, png_const_infop info_ptr,
 
 #ifdef PNG_pHYs_SUPPORTED
 png_uint_32 PNGAPI
-png_get_pHYs(png_const_structp png_ptr, png_const_infop info_ptr,
+png_get_pHYs(png_const_structrp png_ptr, png_const_inforp info_ptr,
     png_uint_32 *res_x, png_uint_32 *res_y, int *unit_type)
 {
    png_uint_32 retval = 0;
@@ -883,7 +953,7 @@ png_get_pHYs(png_const_structp png_ptr, png_const_infop info_ptr,
    png_debug1(1, "in %s retrieval function", "pHYs");
 
    if (png_ptr != NULL && info_ptr != NULL &&
-       (info_ptr->valid & PNG_INFO_pHYs))
+       (info_ptr->valid & PNG_INFO_pHYs) != 0)
    {
       if (res_x != NULL)
       {
@@ -909,13 +979,13 @@ png_get_pHYs(png_const_structp png_ptr, png_const_infop info_ptr,
 #endif /* pHYs */
 
 png_uint_32 PNGAPI
-png_get_PLTE(png_const_structp png_ptr, png_const_infop info_ptr,
+png_get_PLTE(png_const_structrp png_ptr, png_inforp info_ptr,
     png_colorp *palette, int *num_palette)
 {
    png_debug1(1, "in %s retrieval function", "PLTE");
 
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_PLTE)
-       && palette != NULL)
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_PLTE) != 0 && palette != NULL)
    {
       *palette = info_ptr->palette;
       *num_palette = info_ptr->num_palette;
@@ -928,13 +998,13 @@ png_get_PLTE(png_const_structp png_ptr, png_const_infop info_ptr,
 
 #ifdef PNG_sBIT_SUPPORTED
 png_uint_32 PNGAPI
-png_get_sBIT(png_const_structp png_ptr, png_infop info_ptr,
+png_get_sBIT(png_const_structrp png_ptr, png_inforp info_ptr,
     png_color_8p *sig_bit)
 {
    png_debug1(1, "in %s retrieval function", "sBIT");
 
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT)
-       && sig_bit != NULL)
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_sBIT) != 0 && sig_bit != NULL)
    {
       *sig_bit = &(info_ptr->sig_bit);
       return (PNG_INFO_sBIT);
@@ -945,8 +1015,8 @@ png_get_sBIT(png_const_structp png_ptr, png_infop info_ptr,
 #endif
 
 #ifdef PNG_TEXT_SUPPORTED
-png_uint_32 PNGAPI
-png_get_text(png_const_structp png_ptr, png_const_infop info_ptr,
+int PNGAPI
+png_get_text(png_const_structrp png_ptr, png_inforp info_ptr,
     png_textp *text_ptr, int *num_text)
 {
    if (png_ptr != NULL && info_ptr != NULL && info_ptr->num_text > 0)
@@ -960,7 +1030,7 @@ png_get_text(png_const_structp png_ptr, png_const_infop info_ptr,
       if (num_text != NULL)
          *num_text = info_ptr->num_text;
 
-      return ((png_uint_32)info_ptr->num_text);
+      return info_ptr->num_text;
    }
 
    if (num_text != NULL)
@@ -972,12 +1042,13 @@ png_get_text(png_const_structp png_ptr, png_const_infop info_ptr,
 
 #ifdef PNG_tIME_SUPPORTED
 png_uint_32 PNGAPI
-png_get_tIME(png_const_structp png_ptr, png_infop info_ptr, png_timep *mod_time)
+png_get_tIME(png_const_structrp png_ptr, png_inforp info_ptr,
+    png_timep *mod_time)
 {
    png_debug1(1, "in %s retrieval function", "tIME");
 
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME)
-       && mod_time != NULL)
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_tIME) != 0 && mod_time != NULL)
    {
       *mod_time = &(info_ptr->mod_time);
       return (PNG_INFO_tIME);
@@ -989,11 +1060,12 @@ png_get_tIME(png_const_structp png_ptr, png_infop info_ptr, png_timep *mod_time)
 
 #ifdef PNG_tRNS_SUPPORTED
 png_uint_32 PNGAPI
-png_get_tRNS(png_const_structp png_ptr, png_infop info_ptr,
+png_get_tRNS(png_const_structrp png_ptr, png_inforp info_ptr,
     png_bytep *trans_alpha, int *num_trans, png_color_16p *trans_color)
 {
    png_uint_32 retval = 0;
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_tRNS) != 0)
    {
       png_debug1(1, "in %s retrieval function", "tRNS");
 
@@ -1032,9 +1104,9 @@ png_get_tRNS(png_const_structp png_ptr, png_infop info_ptr,
 }
 #endif
 
-#ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
+#ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
 int PNGAPI
-png_get_unknown_chunks(png_const_structp png_ptr, png_const_infop info_ptr,
+png_get_unknown_chunks(png_const_structrp png_ptr, png_inforp info_ptr,
     png_unknown_chunkpp unknowns)
 {
    if (png_ptr != NULL && info_ptr != NULL && unknowns != NULL)
@@ -1049,7 +1121,7 @@ png_get_unknown_chunks(png_const_structp png_ptr, png_const_infop info_ptr,
 
 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
 png_byte PNGAPI
-png_get_rgb_to_gray_status (png_const_structp png_ptr)
+png_get_rgb_to_gray_status (png_const_structrp png_ptr)
 {
    return (png_byte)(png_ptr ? png_ptr->rgb_to_gray_status : 0);
 }
@@ -1057,68 +1129,91 @@ png_get_rgb_to_gray_status (png_const_structp png_ptr)
 
 #ifdef PNG_USER_CHUNKS_SUPPORTED
 png_voidp PNGAPI
-png_get_user_chunk_ptr(png_const_structp png_ptr)
+png_get_user_chunk_ptr(png_const_structrp png_ptr)
 {
    return (png_ptr ? png_ptr->user_chunk_ptr : NULL);
 }
 #endif
 
 png_size_t PNGAPI
-png_get_compression_buffer_size(png_const_structp png_ptr)
+png_get_compression_buffer_size(png_const_structrp png_ptr)
 {
-   return (png_ptr ? png_ptr->zbuf_size : 0);
+   if (png_ptr == NULL)
+      return 0;
+
+#ifdef PNG_WRITE_SUPPORTED
+      if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
+#endif
+   {
+#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
+         return png_ptr->IDAT_read_size;
+#else
+         return PNG_IDAT_READ_SIZE;
+#endif
+   }
+
+#ifdef PNG_WRITE_SUPPORTED
+      else
+         return png_ptr->zbuffer_size;
+#endif
 }
 
 #ifdef PNG_SET_USER_LIMITS_SUPPORTED
 /* These functions were added to libpng 1.2.6 and were enabled
  * by default in libpng-1.4.0 */
 png_uint_32 PNGAPI
-png_get_user_width_max (png_const_structp png_ptr)
+png_get_user_width_max (png_const_structrp png_ptr)
 {
    return (png_ptr ? png_ptr->user_width_max : 0);
 }
 
 png_uint_32 PNGAPI
-png_get_user_height_max (png_const_structp png_ptr)
+png_get_user_height_max (png_const_structrp png_ptr)
 {
    return (png_ptr ? png_ptr->user_height_max : 0);
 }
 
 /* This function was added to libpng 1.4.0 */
 png_uint_32 PNGAPI
-png_get_chunk_cache_max (png_const_structp png_ptr)
+png_get_chunk_cache_max (png_const_structrp png_ptr)
 {
    return (png_ptr ? png_ptr->user_chunk_cache_max : 0);
 }
 
 /* This function was added to libpng 1.4.1 */
 png_alloc_size_t PNGAPI
-png_get_chunk_malloc_max (png_const_structp png_ptr)
+png_get_chunk_malloc_max (png_const_structrp png_ptr)
 {
    return (png_ptr ? png_ptr->user_chunk_malloc_max : 0);
 }
-#endif /* ?PNG_SET_USER_LIMITS_SUPPORTED */
+#endif /* SET_USER_LIMITS */
 
 /* These functions were added to libpng 1.4.0 */
 #ifdef PNG_IO_STATE_SUPPORTED
 png_uint_32 PNGAPI
-png_get_io_state (png_structp png_ptr)
+png_get_io_state (png_const_structrp png_ptr)
 {
    return png_ptr->io_state;
 }
 
 png_uint_32 PNGAPI
-png_get_io_chunk_type (png_const_structp png_ptr)
+png_get_io_chunk_type (png_const_structrp png_ptr)
 {
    return png_ptr->chunk_name;
 }
+#endif /* IO_STATE */
 
-png_const_bytep PNGAPI
-png_get_io_chunk_name (png_structp png_ptr)
+#ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
+#  ifdef PNG_GET_PALETTE_MAX_SUPPORTED
+int PNGAPI
+png_get_palette_max(png_const_structp png_ptr, png_const_infop info_ptr)
 {
-   PNG_CSTRING_FROM_CHUNK(png_ptr->io_chunk_string, png_ptr->chunk_name);
-   return png_ptr->io_chunk_string;
+   if (png_ptr != NULL && info_ptr != NULL)
+      return png_ptr->num_palette_max;
+
+   return (-1);
 }
-#endif /* ?PNG_IO_STATE_SUPPORTED */
+#  endif
+#endif
 
-#endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */
+#endif /* READ || WRITE */
diff --git a/src/3rdparty/libpng/pnginfo.h b/src/3rdparty/libpng/pnginfo.h
index a33bfab..c8c874d 100644
--- a/src/3rdparty/libpng/pnginfo.h
+++ b/src/3rdparty/libpng/pnginfo.h
@@ -1,12 +1,11 @@
 
 /* pnginfo.h - header file for PNG reference library
  *
- * Copyright (c) 1998-2011 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.1 [March 28, 2013]
+ * Copyright (c) 1998-2013 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
- * Last changed in libpng 1.5.0 [January 6, 2011]
- *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
  * and license in png.h
@@ -55,7 +54,7 @@
 
 struct png_info_def
 {
-   /* the following are necessary for every PNG file */
+   /* The following are necessary for every PNG file */
    png_uint_32 width;  /* width of image in pixels (from IHDR) */
    png_uint_32 height; /* height of image in pixels (from IHDR) */
    png_uint_32 valid;  /* valid chunk data (see PNG_INFO_ below) */
@@ -70,11 +69,17 @@ struct png_info_def
    png_byte filter_type;    /* must be PNG_FILTER_TYPE_BASE (from IHDR) */
    png_byte interlace_type; /* One of PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */
 
-   /* The following is informational only on read, and not used on writes. */
+   /* The following are set by png_set_IHDR, called from the application on
+    * write, but the are never actually used by the write code.
+    */
    png_byte channels;       /* number of data channels per pixel (1, 2, 3, 4) */
    png_byte pixel_depth;    /* number of bits per pixel */
    png_byte spare_byte;     /* to align the data, and for future use */
+
+#ifdef PNG_READ_SUPPORTED
+   /* This is never set during write */
    png_byte signature[8];   /* magic bytes read by libpng from start of file */
+#endif
 
    /* The rest of the data is optional.  If you are reading, check the
     * valid field to see if the information in these are valid.  If you
@@ -82,18 +87,25 @@ struct png_info_def
     * and initialize the appropriate fields below.
     */
 
-#if defined(PNG_gAMA_SUPPORTED)
-   /* The gAMA chunk describes the gamma characteristics of the system
-    * on which the image was created, normally in the range [1.0, 2.5].
-    * Data is valid if (valid & PNG_INFO_gAMA) is non-zero.
+#if defined(PNG_COLORSPACE_SUPPORTED) || defined(PNG_GAMMA_SUPPORTED)
+   /* png_colorspace only contains 'flags' if neither GAMMA or COLORSPACE are
+    * defined.  When COLORSPACE is switched on all the colorspace-defining
+    * chunks should be enabled, when GAMMA is switched on all the gamma-defining
+    * chunks should be enabled.  If this is not done it becomes possible to read
+    * inconsistent PNG files and assign a probably incorrect interpretation to
+    * the information.  (In other words, by carefully choosing which chunks to
+    * recognize the system configuration can select an interpretation for PNG
+    * files containing ambiguous data and this will result in inconsistent
+    * behavior between different libpng builds!)
     */
-   png_fixed_point gamma;
+   png_colorspace colorspace;
 #endif
 
-#ifdef PNG_sRGB_SUPPORTED
-    /* GR-P, 0.96a */
-    /* Data valid if (valid & PNG_INFO_sRGB) non-zero. */
-   png_byte srgb_intent; /* sRGB rendering intent [0, 1, 2, or 3] */
+#ifdef PNG_iCCP_SUPPORTED
+   /* iCCP chunk data. */
+   png_charp iccp_name;     /* profile name */
+   png_bytep iccp_profile;  /* International Color Consortium profile data */
+   png_uint_32 iccp_proflen;  /* ICC profile data length */
 #endif
 
 #ifdef PNG_TEXT_SUPPORTED
@@ -108,7 +120,7 @@ struct png_info_def
    int num_text; /* number of comments read or comments to write */
    int max_text; /* current size of text array */
    png_textp text; /* array of comments read or comments to write */
-#endif /* PNG_TEXT_SUPPORTED */
+#endif /* TEXT */
 
 #ifdef PNG_tIME_SUPPORTED
    /* The tIME chunk holds the last time the displayed image data was
@@ -183,23 +195,6 @@ defined(PNG_READ_BACKGROUND_SUPPORTED)
    png_uint_16p hist;
 #endif
 
-#ifdef PNG_cHRM_SUPPORTED
-   /* The cHRM chunk describes the CIE color characteristics of the monitor
-    * on which the PNG was created.  This data allows the viewer to do gamut
-    * mapping of the input image to ensure that the viewer sees the same
-    * colors in the image as the creator.  Values are in the range
-    * [0.0, 0.8].  Data valid if (valid & PNG_INFO_cHRM) non-zero.
-    */
-   png_fixed_point x_white;
-   png_fixed_point y_white;
-   png_fixed_point x_red;
-   png_fixed_point y_red;
-   png_fixed_point x_green;
-   png_fixed_point y_green;
-   png_fixed_point x_blue;
-   png_fixed_point y_blue;
-#endif
-
 #ifdef PNG_pCAL_SUPPORTED
    /* The pCAL chunk describes a transformation between the stored pixel
     * values and original physical data values used to create the image.
@@ -224,25 +219,20 @@ defined(PNG_READ_BACKGROUND_SUPPORTED)
 /* New members added in libpng-1.0.6 */
    png_uint_32 free_me;     /* flags items libpng is responsible for freeing */
 
-#if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED) || \
- defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
+#ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
    /* Storage for unknown chunks that the library doesn't recognize. */
    png_unknown_chunkp unknown_chunks;
-   int unknown_chunks_num;
-#endif
 
-#ifdef PNG_iCCP_SUPPORTED
-   /* iCCP chunk data. */
-   png_charp iccp_name;     /* profile name */
-   png_bytep iccp_profile;  /* International Color Consortium profile data */
-   png_uint_32 iccp_proflen;  /* ICC profile data length */
-   png_byte iccp_compression; /* Always zero */
+   /* The type of this field is limited by the type of 
+    * png_struct::user_chunk_cache_max, else overflow can occur.
+    */
+   int                unknown_chunks_num;
 #endif
 
 #ifdef PNG_sPLT_SUPPORTED
    /* Data on sPLT chunks (there may be more than one). */
    png_sPLT_tp splt_palettes;
-   png_uint_32 splt_palettes_num;
+   int         splt_palettes_num; /* Match type returned by png_get API */
 #endif
 
 #ifdef PNG_sCAL_SUPPORTED
diff --git a/src/3rdparty/libpng/pnglibconf.h b/src/3rdparty/libpng/pnglibconf.h
index aa82b57..f0fdcf8 100644
--- a/src/3rdparty/libpng/pnglibconf.h
+++ b/src/3rdparty/libpng/pnglibconf.h
@@ -1,48 +1,31 @@
-
-/* libpng STANDARD API DEFINITION */
+/* libpng 1.6.17 STANDARD API DEFINITION */
 
 /* pnglibconf.h - library build configuration */
 
-/* Libpng 1.5.10 - March 29, 2012 */
+/* Libpng version 1.6.17 - March 26, 2015 */
 
-/* Copyright (c) 1998-2012 Glenn Randers-Pehrson */
+/* Copyright (c) 1998-2014 Glenn Randers-Pehrson */
 
 /* This code is released under the libpng license. */
 /* For conditions of distribution and use, see the disclaimer */
 /* and license in png.h */
 
 /* pnglibconf.h */
+/* Machine generated file: DO NOT EDIT */
 /* Derived from: scripts/pnglibconf.dfa */
-/* If you edit this file by hand you must obey the rules expressed in */
-/* pnglibconf.dfa with respect to the dependencies between the following */
-/* symbols.  It is much better to generate a new file using */
-/* scripts/libpngconf.mak */
-
 #ifndef PNGLCONF_H
 #define PNGLCONF_H
-/* settings */
-#define PNG_API_RULE 0
-#define PNG_CALLOC_SUPPORTED
-#define PNG_COST_SHIFT 3
-#define PNG_DEFAULT_READ_MACROS 1
-#define PNG_GAMMA_THRESHOLD_FIXED 5000
-#define PNG_MAX_GAMMA_8 11
-#define PNG_QUANTIZE_BLUE_BITS 5
-#define PNG_QUANTIZE_GREEN_BITS 5
-#define PNG_QUANTIZE_RED_BITS 5
-#define PNG_sCAL_PRECISION 5
-#define PNG_WEIGHT_SHIFT 8
-#define PNG_ZBUF_SIZE 8192
-/* end of settings */
 /* options */
 #define PNG_16BIT_SUPPORTED
-#define PNG_ALIGN_MEMORY_SUPPORTED
+#define PNG_ALIGNED_MEMORY_SUPPORTED
+/*#undef PNG_ARM_NEON_API_SUPPORTED*/
+/*#undef PNG_ARM_NEON_CHECK_SUPPORTED*/
 #define PNG_BENIGN_ERRORS_SUPPORTED
-#define PNG_bKGD_SUPPORTED
+#define PNG_BENIGN_READ_ERRORS_SUPPORTED
+/*#undef PNG_BENIGN_WRITE_ERRORS_SUPPORTED*/
 #define PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
-#define PNG_CHECK_cHRM_SUPPORTED
 #define PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
-#define PNG_cHRM_SUPPORTED
+#define PNG_COLORSPACE_SUPPORTED
 #define PNG_CONSOLE_IO_SUPPORTED
 #ifndef _WIN32_WCE
 #define PNG_CONVERT_tIME_SUPPORTED
@@ -53,18 +36,15 @@
 #define PNG_FIXED_POINT_SUPPORTED
 #define PNG_FLOATING_ARITHMETIC_SUPPORTED
 #define PNG_FLOATING_POINT_SUPPORTED
-#define PNG_gAMA_SUPPORTED
+#define PNG_FORMAT_AFIRST_SUPPORTED
+#define PNG_FORMAT_BGR_SUPPORTED
+#define PNG_GAMMA_SUPPORTED
+#define PNG_GET_PALETTE_MAX_SUPPORTED
 #define PNG_HANDLE_AS_UNKNOWN_SUPPORTED
-#define PNG_hIST_SUPPORTED
-#define PNG_iCCP_SUPPORTED
 #define PNG_INCH_CONVERSIONS_SUPPORTED
 #define PNG_INFO_IMAGE_SUPPORTED
 #define PNG_IO_STATE_SUPPORTED
-#define PNG_iTXt_SUPPORTED
 #define PNG_MNG_FEATURES_SUPPORTED
-#define PNG_oFFs_SUPPORTED
-#define PNG_pCAL_SUPPORTED
-#define PNG_pHYs_SUPPORTED
 #define PNG_POINTER_INDEXING_SUPPORTED
 #define PNG_PROGRESSIVE_READ_SUPPORTED
 #define PNG_READ_16BIT_SUPPORTED
@@ -72,68 +52,74 @@
 #define PNG_READ_ANCILLARY_CHUNKS_SUPPORTED
 #define PNG_READ_BACKGROUND_SUPPORTED
 #define PNG_READ_BGR_SUPPORTED
-#define PNG_READ_bKGD_SUPPORTED
 #define PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
-#define PNG_READ_cHRM_SUPPORTED
 #define PNG_READ_COMPOSITE_NODIV_SUPPORTED
 #define PNG_READ_COMPRESSED_TEXT_SUPPORTED
 #define PNG_READ_EXPAND_16_SUPPORTED
 #define PNG_READ_EXPAND_SUPPORTED
 #define PNG_READ_FILLER_SUPPORTED
-#define PNG_READ_gAMA_SUPPORTED
 #define PNG_READ_GAMMA_SUPPORTED
+#define PNG_READ_GET_PALETTE_MAX_SUPPORTED
 #define PNG_READ_GRAY_TO_RGB_SUPPORTED
-#define PNG_READ_hIST_SUPPORTED
-#define PNG_READ_iCCP_SUPPORTED
 #define PNG_READ_INTERLACING_SUPPORTED
 #define PNG_READ_INT_FUNCTIONS_SUPPORTED
 #define PNG_READ_INVERT_ALPHA_SUPPORTED
 #define PNG_READ_INVERT_SUPPORTED
-#define PNG_READ_iTXt_SUPPORTED
-#define PNG_READ_oFFs_SUPPORTED
 #define PNG_READ_OPT_PLTE_SUPPORTED
-#define PNG_READ_PACK_SUPPORTED
 #define PNG_READ_PACKSWAP_SUPPORTED
-#define PNG_READ_pCAL_SUPPORTED
-#define PNG_READ_pHYs_SUPPORTED
+#define PNG_READ_PACK_SUPPORTED
 #define PNG_READ_QUANTIZE_SUPPORTED
 #define PNG_READ_RGB_TO_GRAY_SUPPORTED
-#define PNG_READ_sBIT_SUPPORTED
 #define PNG_READ_SCALE_16_TO_8_SUPPORTED
-#define PNG_READ_sCAL_SUPPORTED
 #define PNG_READ_SHIFT_SUPPORTED
-#define PNG_READ_sPLT_SUPPORTED
-#define PNG_READ_sRGB_SUPPORTED
 #define PNG_READ_STRIP_16_TO_8_SUPPORTED
 #define PNG_READ_STRIP_ALPHA_SUPPORTED
 #define PNG_READ_SUPPORTED
 #define PNG_READ_SWAP_ALPHA_SUPPORTED
 #define PNG_READ_SWAP_SUPPORTED
-#define PNG_READ_tEXt_SUPPORTED
 #define PNG_READ_TEXT_SUPPORTED
-#define PNG_READ_tIME_SUPPORTED
 #define PNG_READ_TRANSFORMS_SUPPORTED
-#define PNG_READ_tRNS_SUPPORTED
 #define PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
 #define PNG_READ_USER_CHUNKS_SUPPORTED
 #define PNG_READ_USER_TRANSFORM_SUPPORTED
+#define PNG_READ_bKGD_SUPPORTED
+#define PNG_READ_cHRM_SUPPORTED
+#define PNG_READ_gAMA_SUPPORTED
+#define PNG_READ_hIST_SUPPORTED
+#define PNG_READ_iCCP_SUPPORTED
+#define PNG_READ_iTXt_SUPPORTED
+#define PNG_READ_oFFs_SUPPORTED
+#define PNG_READ_pCAL_SUPPORTED
+#define PNG_READ_pHYs_SUPPORTED
+#define PNG_READ_sBIT_SUPPORTED
+#define PNG_READ_sCAL_SUPPORTED
+#define PNG_READ_sPLT_SUPPORTED
+#define PNG_READ_sRGB_SUPPORTED
+#define PNG_READ_tEXt_SUPPORTED
+#define PNG_READ_tIME_SUPPORTED
+#define PNG_READ_tRNS_SUPPORTED
 #define PNG_READ_zTXt_SUPPORTED
 #define PNG_SAVE_INT_32_SUPPORTED
-#define PNG_sBIT_SUPPORTED
-#define PNG_sCAL_SUPPORTED
+#define PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
 #define PNG_SEQUENTIAL_READ_SUPPORTED
+#define PNG_SETJMP_SUPPORTED
 #define PNG_SET_CHUNK_CACHE_LIMIT_SUPPORTED
 #define PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
-#define PNG_SETJMP_SUPPORTED
+#define PNG_SET_OPTION_SUPPORTED
+#define PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
 #define PNG_SET_USER_LIMITS_SUPPORTED
-#define PNG_sPLT_SUPPORTED
-#define PNG_sRGB_SUPPORTED
+#ifndef _WIN32_WCE
+#define PNG_SIMPLIFIED_READ_AFIRST_SUPPORTED
+#define PNG_SIMPLIFIED_READ_BGR_SUPPORTED
+#define PNG_SIMPLIFIED_READ_SUPPORTED
+#define PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
+#define PNG_SIMPLIFIED_WRITE_BGR_SUPPORTED
+#define PNG_SIMPLIFIED_WRITE_SUPPORTED
+#endif
 #define PNG_STDIO_SUPPORTED
-#define PNG_tEXt_SUPPORTED
+#define PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
 #define PNG_TEXT_SUPPORTED
 #define PNG_TIME_RFC1123_SUPPORTED
-#define PNG_tIME_SUPPORTED
-#define PNG_tRNS_SUPPORTED
 #define PNG_UNKNOWN_CHUNKS_SUPPORTED
 #define PNG_USER_CHUNKS_SUPPORTED
 #define PNG_USER_LIMITS_SUPPORTED
@@ -144,46 +130,89 @@
 #define PNG_WRITE_16BIT_SUPPORTED
 #define PNG_WRITE_ANCILLARY_CHUNKS_SUPPORTED
 #define PNG_WRITE_BGR_SUPPORTED
-#define PNG_WRITE_bKGD_SUPPORTED
 #define PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED
-#define PNG_WRITE_cHRM_SUPPORTED
 #define PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
+#define PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED
 #define PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
 #define PNG_WRITE_FILLER_SUPPORTED
 #define PNG_WRITE_FILTER_SUPPORTED
 #define PNG_WRITE_FLUSH_SUPPORTED
-#define PNG_WRITE_gAMA_SUPPORTED
-#define PNG_WRITE_hIST_SUPPORTED
-#define PNG_WRITE_iCCP_SUPPORTED
+#define PNG_WRITE_GET_PALETTE_MAX_SUPPORTED
 #define PNG_WRITE_INTERLACING_SUPPORTED
 #define PNG_WRITE_INT_FUNCTIONS_SUPPORTED
 #define PNG_WRITE_INVERT_ALPHA_SUPPORTED
 #define PNG_WRITE_INVERT_SUPPORTED
-#define PNG_WRITE_iTXt_SUPPORTED
-#define PNG_WRITE_oFFs_SUPPORTED
 #define PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
-#define PNG_WRITE_PACK_SUPPORTED
 #define PNG_WRITE_PACKSWAP_SUPPORTED
-#define PNG_WRITE_pCAL_SUPPORTED
-#define PNG_WRITE_pHYs_SUPPORTED
-#define PNG_WRITE_sBIT_SUPPORTED
-#define PNG_WRITE_sCAL_SUPPORTED
+#define PNG_WRITE_PACK_SUPPORTED
 #define PNG_WRITE_SHIFT_SUPPORTED
-#define PNG_WRITE_sPLT_SUPPORTED
-#define PNG_WRITE_sRGB_SUPPORTED
 #define PNG_WRITE_SUPPORTED
 #define PNG_WRITE_SWAP_ALPHA_SUPPORTED
 #define PNG_WRITE_SWAP_SUPPORTED
-#define PNG_WRITE_tEXt_SUPPORTED
 #define PNG_WRITE_TEXT_SUPPORTED
-#define PNG_WRITE_tIME_SUPPORTED
 #define PNG_WRITE_TRANSFORMS_SUPPORTED
-#define PNG_WRITE_tRNS_SUPPORTED
 #define PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
 #define PNG_WRITE_USER_TRANSFORM_SUPPORTED
 #define PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
+#define PNG_WRITE_bKGD_SUPPORTED
+#define PNG_WRITE_cHRM_SUPPORTED
+#define PNG_WRITE_gAMA_SUPPORTED
+#define PNG_WRITE_hIST_SUPPORTED
+#define PNG_WRITE_iCCP_SUPPORTED
+#define PNG_WRITE_iTXt_SUPPORTED
+#define PNG_WRITE_oFFs_SUPPORTED
+#define PNG_WRITE_pCAL_SUPPORTED
+#define PNG_WRITE_pHYs_SUPPORTED
+#define PNG_WRITE_sBIT_SUPPORTED
+#define PNG_WRITE_sCAL_SUPPORTED
+#define PNG_WRITE_sPLT_SUPPORTED
+#define PNG_WRITE_sRGB_SUPPORTED
+#define PNG_WRITE_tEXt_SUPPORTED
+#define PNG_WRITE_tIME_SUPPORTED
+#define PNG_WRITE_tRNS_SUPPORTED
 #define PNG_WRITE_zTXt_SUPPORTED
+#define PNG_bKGD_SUPPORTED
+#define PNG_cHRM_SUPPORTED
+#define PNG_gAMA_SUPPORTED
+#define PNG_hIST_SUPPORTED
+#define PNG_iCCP_SUPPORTED
+#define PNG_iTXt_SUPPORTED
+#define PNG_oFFs_SUPPORTED
+#define PNG_pCAL_SUPPORTED
+#define PNG_pHYs_SUPPORTED
+#define PNG_sBIT_SUPPORTED
+#define PNG_sCAL_SUPPORTED
+#define PNG_sPLT_SUPPORTED
+#define PNG_sRGB_SUPPORTED
+#define PNG_tEXt_SUPPORTED
+#define PNG_tIME_SUPPORTED
+#define PNG_tRNS_SUPPORTED
 #define PNG_zTXt_SUPPORTED
 /* end of options */
-#define PNG_SAFE_LIMITS_SUPPORTED
+/* settings */
+#define PNG_API_RULE 0
+#define PNG_COST_SHIFT 3
+#define PNG_DEFAULT_READ_MACROS 1
+#define PNG_GAMMA_THRESHOLD_FIXED 5000
+#define PNG_IDAT_READ_SIZE PNG_ZBUF_SIZE
+#define PNG_INFLATE_BUF_SIZE 1024
+#define PNG_MAX_GAMMA_8 11
+#define PNG_QUANTIZE_BLUE_BITS 5
+#define PNG_QUANTIZE_GREEN_BITS 5
+#define PNG_QUANTIZE_RED_BITS 5
+#define PNG_TEXT_Z_DEFAULT_COMPRESSION (-1)
+#define PNG_TEXT_Z_DEFAULT_STRATEGY 0
+#define PNG_USER_CHUNK_CACHE_MAX 1000
+#define PNG_USER_CHUNK_MALLOC_MAX 8000000
+#define PNG_USER_HEIGHT_MAX 1000000
+#define PNG_USER_WIDTH_MAX 1000000
+#define PNG_WEIGHT_SHIFT 8
+#define PNG_ZBUF_SIZE 8192
+#define PNG_ZLIB_VERNUM 0 /* unknown */
+#define PNG_Z_DEFAULT_COMPRESSION (-1)
+#define PNG_Z_DEFAULT_NOFILTER_STRATEGY 0
+#define PNG_Z_DEFAULT_STRATEGY 1
+#define PNG_sCAL_PRECISION 5
+#define PNG_sRGB_PROFILE_CHECKS 2
+/* end of settings */
 #endif /* PNGLCONF_H */
diff --git a/src/3rdparty/libpng/pngmem.c b/src/3rdparty/libpng/pngmem.c
index bf5ff03..8b157e5 100644
--- a/src/3rdparty/libpng/pngmem.c
+++ b/src/3rdparty/libpng/pngmem.c
@@ -1,8 +1,8 @@
 
 /* pngmem.c - stub functions for memory allocation
  *
- * Last changed in libpng 1.5.7 [December 15, 2011]
- * Copyright (c) 1998-2011 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.15 [November 20, 2014]
+ * Copyright (c) 1998-2014 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
@@ -20,627 +20,241 @@
 #include "pngpriv.h"
 
 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
-
-/* Borland DOS special memory handler */
-#if defined(__TURBOC__) && !defined(_Windows) && !defined(__FLAT__)
-/* If you change this, be sure to change the one in png.h also */
-
-/* Allocate memory for a png_struct.  The malloc and memset can be replaced
-   by a single call to calloc() if this is thought to improve performance. */
-PNG_FUNCTION(png_voidp /* PRIVATE */,
-png_create_struct,(int type),PNG_ALLOCATED)
-{
-#  ifdef PNG_USER_MEM_SUPPORTED
-   return (png_create_struct_2(type, NULL, NULL));
-}
-
-/* Alternate version of png_create_struct, for use with user-defined malloc. */
-PNG_FUNCTION(png_voidp /* PRIVATE */,
-png_create_struct_2,(int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr),
-   PNG_ALLOCATED)
-{
-#  endif /* PNG_USER_MEM_SUPPORTED */
-   png_size_t size;
-   png_voidp struct_ptr;
-
-   if (type == PNG_STRUCT_INFO)
-      size = png_sizeof(png_info);
-
-   else if (type == PNG_STRUCT_PNG)
-      size = png_sizeof(png_struct);
-
-   else
-      return (png_get_copyright(NULL));
-
-#  ifdef PNG_USER_MEM_SUPPORTED
-   if (malloc_fn != NULL)
-   {
-      png_struct dummy_struct;
-      memset(&dummy_struct, 0, sizeof dummy_struct);
-      dummy_struct.mem_ptr=mem_ptr;
-      struct_ptr = (*(malloc_fn))(&dummy_struct, (png_alloc_size_t)size);
-   }
-
-   else
-#  endif /* PNG_USER_MEM_SUPPORTED */
-   struct_ptr = (png_voidp)farmalloc(size);
-   if (struct_ptr != NULL)
-      png_memset(struct_ptr, 0, size);
-
-   return (struct_ptr);
-}
-
-/* Free memory allocated by a png_create_struct() call */
+/* Free a png_struct */
 void /* PRIVATE */
-png_destroy_struct(png_voidp struct_ptr)
+png_destroy_png_struct(png_structrp png_ptr)
 {
-#  ifdef PNG_USER_MEM_SUPPORTED
-   png_destroy_struct_2(struct_ptr, NULL, NULL);
-}
-
-/* Free memory allocated by a png_create_struct() call */
-void /* PRIVATE */
-png_destroy_struct_2(png_voidp struct_ptr, png_free_ptr free_fn,
-    png_voidp mem_ptr)
-{
-#  endif
-   if (struct_ptr != NULL)
+   if (png_ptr != NULL)
    {
-#  ifdef PNG_USER_MEM_SUPPORTED
-      if (free_fn != NULL)
-      {
-         png_struct dummy_struct;
-         memset(&dummy_struct, 0, sizeof dummy_struct);
-         dummy_struct.mem_ptr=mem_ptr;
-         (*(free_fn))(&dummy_struct, struct_ptr);
-         return;
-      }
-
-#  endif /* PNG_USER_MEM_SUPPORTED */
-      farfree (struct_ptr);
+      /* png_free might call png_error and may certainly call
+       * png_get_mem_ptr, so fake a temporary png_struct to support this.
+       */
+      png_struct dummy_struct = *png_ptr;
+      memset(png_ptr, 0, (sizeof *png_ptr));
+      png_free(&dummy_struct, png_ptr);
+
+#     ifdef PNG_SETJMP_SUPPORTED
+         /* We may have a jmp_buf left to deallocate. */
+         png_free_jmpbuf(&dummy_struct);
+#     endif
    }
 }
 
 /* Allocate memory.  For reasonable files, size should never exceed
- * 64K.  However, zlib may allocate more then 64K if you don't tell
- * it not to.  See zconf.h and png.h for more information. zlib does
+ * 64K.  However, zlib may allocate more than 64K if you don't tell
+ * it not to.  See zconf.h and png.h for more information.  zlib does
  * need to allocate exactly 64K, so whatever you call here must
  * have the ability to do that.
- *
- * Borland seems to have a problem in DOS mode for exactly 64K.
- * It gives you a segment with an offset of 8 (perhaps to store its
- * memory stuff).  zlib doesn't like this at all, so we have to
- * detect and deal with it.  This code should not be needed in
- * Windows or OS/2 modes, and only in 16 bit mode.  This code has
- * been updated by Alexander Lehmann for version 0.89 to waste less
- * memory.
- *
- * Note that we can't use png_size_t for the "size" declaration,
- * since on some systems a png_size_t is a 16-bit quantity, and as a
- * result, we would be truncating potentially larger memory requests
- * (which should cause a fatal error) and introducing major problems.
  */
 PNG_FUNCTION(png_voidp,PNGAPI
-png_calloc,(png_structp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
+png_calloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
 {
    png_voidp ret;
 
-   ret = (png_malloc(png_ptr, size));
+   ret = png_malloc(png_ptr, size);
 
    if (ret != NULL)
-      png_memset(ret,0,(png_size_t)size);
-
-   return (ret);
-}
-
-PNG_FUNCTION(png_voidp,PNGAPI
-png_malloc,(png_structp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
-{
-   png_voidp ret;
-
-   if (png_ptr == NULL || size == 0)
-      return (NULL);
-
-#  ifdef PNG_USER_MEM_SUPPORTED
-   if (png_ptr->malloc_fn != NULL)
-      ret = ((png_voidp)(*(png_ptr->malloc_fn))(png_ptr, size));
-
-   else
-      ret = (png_malloc_default(png_ptr, size));
-
-   if (ret == NULL && (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
-       png_error(png_ptr, "Out of memory");
+      memset(ret, 0, size);
 
-   return (ret);
+   return ret;
 }
 
-PNG_FUNCTION(png_voidp,PNGAPI
-png_malloc_default,(png_structp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
+/* png_malloc_base, an internal function added at libpng 1.6.0, does the work of
+ * allocating memory, taking into account limits and PNG_USER_MEM_SUPPORTED.
+ * Checking and error handling must happen outside this routine; it returns NULL
+ * if the allocation cannot be done (for any reason.)
+ */
+PNG_FUNCTION(png_voidp /* PRIVATE */,
+png_malloc_base,(png_const_structrp png_ptr, png_alloc_size_t size),
+   PNG_ALLOCATED)
 {
-   png_voidp ret;
-#  endif /* PNG_USER_MEM_SUPPORTED */
-
-   if (png_ptr == NULL || size == 0)
-      return (NULL);
-
-#  ifdef PNG_MAX_MALLOC_64K
-   if (size > (png_uint_32)65536L)
-   {
-      png_warning(png_ptr, "Cannot Allocate > 64K");
-      ret = NULL;
-   }
-
-   else
-#  endif
-
-   if (size != (size_t)size)
-      ret = NULL;
-
-   else if (size == (png_uint_32)65536L)
+   /* Moved to png_malloc_base from png_malloc_default in 1.6.0; the DOS
+    * allocators have also been removed in 1.6.0, so any 16-bit system now has
+    * to implement a user memory handler.  This checks to be sure it isn't
+    * called with big numbers.
+    */
+#ifndef PNG_USER_MEM_SUPPORTED
+   PNG_UNUSED(png_ptr)
+#endif
+
+   if (size > 0 && size <= PNG_SIZE_MAX
+#     ifdef PNG_MAX_MALLOC_64K
+         && size <= 65536U
+#     endif
+      )
    {
-      if (png_ptr->offset_table == NULL)
-      {
-         /* Try to see if we need to do any of this fancy stuff */
-         ret = farmalloc(size);
-         if (ret == NULL || ((png_size_t)ret & 0xffff))
-         {
-            int num_blocks;
-            png_uint_32 total_size;
-            png_bytep table;
-            int i, mem_level, window_bits;
-            png_byte huge * hptr;
-            int window_bits
-
-            if (ret != NULL)
-            {
-               farfree(ret);
-               ret = NULL;
-            }
-
-            window_bits =
-                png_ptr->zlib_window_bits >= png_ptr->zlib_text_window_bits ?
-                png_ptr->zlib_window_bits : png_ptr->zlib_text_window_bits;
-
-            if (window_bits > 14)
-               num_blocks = (int)(1 << (window_bits - 14));
-
-            else
-               num_blocks = 1;
-
-            mem_level =
-                png_ptr->zlib_mem_level >= png_ptr->zlib_text_mem_level ?
-                png_ptr->zlib_mem_level : png_ptr->zlib_text_mem_level;
-
-            if (mem_level >= 7)
-               num_blocks += (int)(1 << (mem_level - 7));
-
-            else
-               num_blocks++;
-
-            total_size = ((png_uint_32)65536L) * (png_uint_32)num_blocks+16;
-
-            table = farmalloc(total_size);
-
-            if (table == NULL)
-            {
-#  ifndef PNG_USER_MEM_SUPPORTED
-               if ((png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
-                  png_error(png_ptr, "Out Of Memory"); /* Note "O", "M" */
-
-               else
-                  png_warning(png_ptr, "Out Of Memory");
-#  endif
-               return (NULL);
-            }
-
-            if ((png_size_t)table & 0xfff0)
-            {
-#  ifndef PNG_USER_MEM_SUPPORTED
-               if ((png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
-                  png_error(png_ptr,
-                    "Farmalloc didn't return normalized pointer");
-
-               else
-                  png_warning(png_ptr,
-                    "Farmalloc didn't return normalized pointer");
-#  endif
-               return (NULL);
-            }
-
-            png_ptr->offset_table = table;
-            png_ptr->offset_table_ptr = farmalloc(num_blocks *
-               png_sizeof(png_bytep));
-
-            if (png_ptr->offset_table_ptr == NULL)
-            {
-#  ifndef PNG_USER_MEM_SUPPORTED
-               if ((png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
-                  png_error(png_ptr, "Out Of memory"); /* Note "O", "m" */
-
-               else
-                  png_warning(png_ptr, "Out Of memory");
-#  endif
-               return (NULL);
-            }
-
-            hptr = (png_byte huge *)table;
-            if ((png_size_t)hptr & 0xf)
-            {
-               hptr = (png_byte huge *)((long)(hptr) & 0xfffffff0L);
-               hptr = hptr + 16L;  /* "hptr += 16L" fails on Turbo C++ 3.0 */
-            }
-
-            for (i = 0; i < num_blocks; i++)
-            {
-               png_ptr->offset_table_ptr[i] = (png_bytep)hptr;
-               hptr = hptr + (png_uint_32)65536L;  /* "+=" fails on TC++3.0 */
-            }
-
-            png_ptr->offset_table_number = num_blocks;
-            png_ptr->offset_table_count = 0;
-            png_ptr->offset_table_count_free = 0;
-         }
-      }
-
-      if (png_ptr->offset_table_count >= png_ptr->offset_table_number)
-      {
-#  ifndef PNG_USER_MEM_SUPPORTED
-         if ((png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
-            png_error(png_ptr, "Out of Memory"); /* Note "O" and "M" */
-
-         else
-            png_warning(png_ptr, "Out of Memory");
-#  endif
-         return (NULL);
-      }
-
-      ret = png_ptr->offset_table_ptr[png_ptr->offset_table_count++];
-   }
-
-   else
-      ret = farmalloc(size);
-
-#  ifndef PNG_USER_MEM_SUPPORTED
-   if (ret == NULL)
-   {
-      if ((png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
-         png_error(png_ptr, "Out of memory"); /* Note "o" and "m" */
+#ifdef PNG_USER_MEM_SUPPORTED
+      if (png_ptr != NULL && png_ptr->malloc_fn != NULL)
+         return png_ptr->malloc_fn(png_constcast(png_structrp,png_ptr), size);
 
       else
-         png_warning(png_ptr, "Out of memory"); /* Note "o" and "m" */
+#endif
+         return malloc((size_t)size); /* checked for truncation above */
    }
-#  endif
 
-   return (ret);
+   else
+      return NULL;
 }
 
-/* Free a pointer allocated by png_malloc().  In the default
- * configuration, png_ptr is not used, but is passed in case it
- * is needed.  If ptr is NULL, return without taking any action.
+#if defined(PNG_TEXT_SUPPORTED) || defined(PNG_sPLT_SUPPORTED) ||\
+   defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED)
+/* This is really here only to work round a spurious warning in GCC 4.6 and 4.7
+ * that arises because of the checks in png_realloc_array that are repeated in
+ * png_malloc_array.
  */
-void PNGAPI
-png_free(png_structp png_ptr, png_voidp ptr)
+static png_voidp
+png_malloc_array_checked(png_const_structrp png_ptr, int nelements,
+   size_t element_size)
 {
-   if (png_ptr == NULL || ptr == NULL)
-      return;
+   png_alloc_size_t req = nelements; /* known to be > 0 */
 
-#  ifdef PNG_USER_MEM_SUPPORTED
-   if (png_ptr->free_fn != NULL)
-   {
-      (*(png_ptr->free_fn))(png_ptr, ptr);
-      return;
-   }
+   if (req <= PNG_SIZE_MAX/element_size)
+      return png_malloc_base(png_ptr, req * element_size);
 
-   else
-      png_free_default(png_ptr, ptr);
+   /* The failure case when the request is too large */
+   return NULL;
 }
 
-void PNGAPI
-png_free_default(png_structp png_ptr, png_voidp ptr)
-{
-#  endif /* PNG_USER_MEM_SUPPORTED */
-
-   if (png_ptr == NULL || ptr == NULL)
-      return;
-
-   if (png_ptr->offset_table != NULL)
-   {
-      int i;
-
-      for (i = 0; i < png_ptr->offset_table_count; i++)
-      {
-         if (ptr == png_ptr->offset_table_ptr[i])
-         {
-            ptr = NULL;
-            png_ptr->offset_table_count_free++;
-            break;
-         }
-      }
-      if (png_ptr->offset_table_count_free == png_ptr->offset_table_count)
-      {
-         farfree(png_ptr->offset_table);
-         farfree(png_ptr->offset_table_ptr);
-         png_ptr->offset_table = NULL;
-         png_ptr->offset_table_ptr = NULL;
-      }
-   }
-
-   if (ptr != NULL)
-      farfree(ptr);
-}
-
-#else /* Not the Borland DOS special memory handler */
-
-/* Allocate memory for a png_struct or a png_info.  The malloc and
-   memset can be replaced by a single call to calloc() if this is thought
-   to improve performance noticably. */
 PNG_FUNCTION(png_voidp /* PRIVATE */,
-png_create_struct,(int type),PNG_ALLOCATED)
+png_malloc_array,(png_const_structrp png_ptr, int nelements,
+   size_t element_size),PNG_ALLOCATED)
 {
-#  ifdef PNG_USER_MEM_SUPPORTED
-   return (png_create_struct_2(type, NULL, NULL));
+   if (nelements <= 0 || element_size == 0)
+      png_error(png_ptr, "internal error: array alloc");
+
+   return png_malloc_array_checked(png_ptr, nelements, element_size);
 }
 
-/* Allocate memory for a png_struct or a png_info.  The malloc and
-   memset can be replaced by a single call to calloc() if this is thought
-   to improve performance noticably. */
 PNG_FUNCTION(png_voidp /* PRIVATE */,
-png_create_struct_2,(int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr),
-   PNG_ALLOCATED)
+png_realloc_array,(png_const_structrp png_ptr, png_const_voidp old_array,
+   int old_elements, int add_elements, size_t element_size),PNG_ALLOCATED)
 {
-#  endif /* PNG_USER_MEM_SUPPORTED */
-   png_size_t size;
-   png_voidp struct_ptr;
-
-   if (type == PNG_STRUCT_INFO)
-      size = png_sizeof(png_info);
-
-   else if (type == PNG_STRUCT_PNG)
-      size = png_sizeof(png_struct);
-
-   else
-      return (NULL);
-
-#  ifdef PNG_USER_MEM_SUPPORTED
-   if (malloc_fn != NULL)
+   /* These are internal errors: */
+   if (add_elements <= 0 || element_size == 0 || old_elements < 0 ||
+      (old_array == NULL && old_elements > 0))
+      png_error(png_ptr, "internal error: array realloc");
+
+   /* Check for overflow on the elements count (so the caller does not have to
+    * check.)
+    */
+   if (add_elements <= INT_MAX - old_elements)
    {
-      png_struct dummy_struct;
-      png_structp png_ptr = &dummy_struct;
-      png_ptr->mem_ptr=mem_ptr;
-      struct_ptr = (*(malloc_fn))(png_ptr, size);
-
-      if (struct_ptr != NULL)
-         png_memset(struct_ptr, 0, size);
-
-      return (struct_ptr);
-   }
-#  endif /* PNG_USER_MEM_SUPPORTED */
-
-#  if defined(__TURBOC__) && !defined(__FLAT__)
-   struct_ptr = (png_voidp)farmalloc(size);
-#  else
-#    if defined(_MSC_VER) && defined(MAXSEG_64K)
-   struct_ptr = (png_voidp)halloc(size, 1);
-#    else
-   struct_ptr = (png_voidp)malloc(size);
-#    endif
-#  endif
-
-   if (struct_ptr != NULL)
-      png_memset(struct_ptr, 0, size);
-
-   return (struct_ptr);
-}
-
+      png_voidp new_array = png_malloc_array_checked(png_ptr,
+         old_elements+add_elements, element_size);
 
-/* Free memory allocated by a png_create_struct() call */
-void /* PRIVATE */
-png_destroy_struct(png_voidp struct_ptr)
-{
-#  ifdef PNG_USER_MEM_SUPPORTED
-   png_destroy_struct_2(struct_ptr, NULL, NULL);
-}
-
-/* Free memory allocated by a png_create_struct() call */
-void /* PRIVATE */
-png_destroy_struct_2(png_voidp struct_ptr, png_free_ptr free_fn,
-    png_voidp mem_ptr)
-{
-#  endif /* PNG_USER_MEM_SUPPORTED */
-   if (struct_ptr != NULL)
-   {
-#  ifdef PNG_USER_MEM_SUPPORTED
-      if (free_fn != NULL)
+      if (new_array != NULL)
       {
-         png_struct dummy_struct;
-         png_structp png_ptr = &dummy_struct;
-         png_ptr->mem_ptr=mem_ptr;
-         (*(free_fn))(png_ptr, struct_ptr);
-         return;
-      }
-#  endif /* PNG_USER_MEM_SUPPORTED */
-#  if defined(__TURBOC__) && !defined(__FLAT__)
-      farfree(struct_ptr);
-
-#  else
-#    if defined(_MSC_VER) && defined(MAXSEG_64K)
-      hfree(struct_ptr);
+         /* Because png_malloc_array worked the size calculations below cannot
+          * overflow.
+          */
+         if (old_elements > 0)
+            memcpy(new_array, old_array, element_size*(unsigned)old_elements);
 
-#    else
-      free(struct_ptr);
+         memset((char*)new_array + element_size*(unsigned)old_elements, 0,
+            element_size*(unsigned)add_elements);
 
-#    endif
-#  endif
+         return new_array;
+      }
    }
+
+   return NULL; /* error */
 }
+#endif /* TEXT || sPLT || STORE_UNKNOWN_CHUNKS */
 
-/* Allocate memory.  For reasonable files, size should never exceed
- * 64K.  However, zlib may allocate more then 64K if you don't tell
- * it not to.  See zconf.h and png.h for more information.  zlib does
- * need to allocate exactly 64K, so whatever you call here must
- * have the ability to do that.
+/* Various functions that have different error handling are derived from this.
+ * png_malloc always exists, but if PNG_USER_MEM_SUPPORTED is defined a separate
+ * function png_malloc_default is also provided.
  */
-
 PNG_FUNCTION(png_voidp,PNGAPI
-png_calloc,(png_structp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
+png_malloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
 {
    png_voidp ret;
 
-   ret = (png_malloc(png_ptr, size));
+   if (png_ptr == NULL)
+      return NULL;
 
-   if (ret != NULL)
-      png_memset(ret,0,(png_size_t)size);
+   ret = png_malloc_base(png_ptr, size);
 
-   return (ret);
+   if (ret == NULL)
+       png_error(png_ptr, "Out of memory"); /* 'm' means png_malloc */
+
+   return ret;
 }
 
+#ifdef PNG_USER_MEM_SUPPORTED
 PNG_FUNCTION(png_voidp,PNGAPI
-png_malloc,(png_structp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
+png_malloc_default,(png_const_structrp png_ptr, png_alloc_size_t size),
+   PNG_ALLOCATED PNG_DEPRECATED)
 {
    png_voidp ret;
 
-#  ifdef PNG_USER_MEM_SUPPORTED
-   if (png_ptr == NULL || size == 0)
-      return (NULL);
-
-   if (png_ptr->malloc_fn != NULL)
-      ret = ((png_voidp)(*(png_ptr->malloc_fn))(png_ptr, (png_size_t)size));
+   if (png_ptr == NULL)
+      return NULL;
 
-   else
-      ret = (png_malloc_default(png_ptr, size));
+   /* Passing 'NULL' here bypasses the application provided memory handler. */
+   ret = png_malloc_base(NULL/*use malloc*/, size);
 
-   if (ret == NULL && (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
-       png_error(png_ptr, "Out of Memory");
+   if (ret == NULL)
+      png_error(png_ptr, "Out of Memory"); /* 'M' means png_malloc_default */
 
-   return (ret);
+   return ret;
 }
+#endif /* USER_MEM */
 
+/* This function was added at libpng version 1.2.3.  The png_malloc_warn()
+ * function will issue a png_warning and return NULL instead of issuing a
+ * png_error, if it fails to allocate the requested memory.
+ */
 PNG_FUNCTION(png_voidp,PNGAPI
-png_malloc_default,(png_structp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
+png_malloc_warn,(png_const_structrp png_ptr, png_alloc_size_t size),
+   PNG_ALLOCATED)
 {
-   png_voidp ret;
-#  endif /* PNG_USER_MEM_SUPPORTED */
-
-   if (png_ptr == NULL || size == 0)
-      return (NULL);
-
-#  ifdef PNG_MAX_MALLOC_64K
-   if (size > (png_uint_32)65536L)
+   if (png_ptr != NULL)
    {
-#    ifndef PNG_USER_MEM_SUPPORTED
-      if ((png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
-         png_error(png_ptr, "Cannot Allocate > 64K");
-
-      else
-#    endif
-         return NULL;
-   }
-#  endif
-
-   /* Check for overflow */
-#  if defined(__TURBOC__) && !defined(__FLAT__)
-
-   if (size != (unsigned long)size)
-      ret = NULL;
-
-   else
-      ret = farmalloc(size);
-
-#  else
-#    if defined(_MSC_VER) && defined(MAXSEG_64K)
-   if (size != (unsigned long)size)
-      ret = NULL;
-
-   else
-      ret = halloc(size, 1);
+      png_voidp ret = png_malloc_base(png_ptr, size);
 
-#    else
-   if (size != (size_t)size)
-      ret = NULL;
+      if (ret != NULL)
+         return ret;
 
-   else
-      ret = malloc((size_t)size);
-#    endif
-#  endif
-
-#  ifndef PNG_USER_MEM_SUPPORTED
-   if (ret == NULL && (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
-      png_error(png_ptr, "Out of Memory");
-#  endif
+      png_warning(png_ptr, "Out of memory");
+   }
 
-   return (ret);
+   return NULL;
 }
 
 /* Free a pointer allocated by png_malloc().  If ptr is NULL, return
  * without taking any action.
  */
 void PNGAPI
-png_free(png_structp png_ptr, png_voidp ptr)
+png_free(png_const_structrp png_ptr, png_voidp ptr)
 {
    if (png_ptr == NULL || ptr == NULL)
       return;
 
-#  ifdef PNG_USER_MEM_SUPPORTED
+#ifdef PNG_USER_MEM_SUPPORTED
    if (png_ptr->free_fn != NULL)
-   {
-      (*(png_ptr->free_fn))(png_ptr, ptr);
-      return;
-   }
+      png_ptr->free_fn(png_constcast(png_structrp,png_ptr), ptr);
 
    else
       png_free_default(png_ptr, ptr);
 }
 
-void PNGAPI
-png_free_default(png_structp png_ptr, png_voidp ptr)
+PNG_FUNCTION(void,PNGAPI
+png_free_default,(png_const_structrp png_ptr, png_voidp ptr),PNG_DEPRECATED)
 {
    if (png_ptr == NULL || ptr == NULL)
       return;
+#endif /* USER_MEM */
 
-#  endif /* PNG_USER_MEM_SUPPORTED */
-
-#  if defined(__TURBOC__) && !defined(__FLAT__)
-   farfree(ptr);
-
-#  else
-#    if defined(_MSC_VER) && defined(MAXSEG_64K)
-   hfree(ptr);
-
-#    else
    free(ptr);
-
-#    endif
-#  endif
-}
-#endif /* Not Borland DOS special memory handler */
-
-/* This function was added at libpng version 1.2.3.  The png_malloc_warn()
- * function will set up png_malloc() to issue a png_warning and return NULL
- * instead of issuing a png_error, if it fails to allocate the requested
- * memory.
- */
-PNG_FUNCTION(png_voidp,PNGAPI
-png_malloc_warn,(png_structp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
-{
-   png_voidp ptr;
-   png_uint_32 save_flags;
-   if (png_ptr == NULL)
-      return (NULL);
-
-   save_flags = png_ptr->flags;
-   png_ptr->flags|=PNG_FLAG_MALLOC_NULL_MEM_OK;
-   ptr = (png_voidp)png_malloc((png_structp)png_ptr, size);
-   png_ptr->flags=save_flags;
-   return(ptr);
 }
 
-
 #ifdef PNG_USER_MEM_SUPPORTED
 /* This function is called when the application wants to use another method
  * of allocating and freeing memory.
  */
 void PNGAPI
-png_set_mem_fn(png_structp png_ptr, png_voidp mem_ptr, png_malloc_ptr
+png_set_mem_fn(png_structrp png_ptr, png_voidp mem_ptr, png_malloc_ptr
   malloc_fn, png_free_ptr free_fn)
 {
    if (png_ptr != NULL)
@@ -656,12 +270,12 @@ png_set_mem_fn(png_structp png_ptr, png_voidp mem_ptr, png_malloc_ptr
  * pointer before png_write_destroy and png_read_destroy are called.
  */
 png_voidp PNGAPI
-png_get_mem_ptr(png_const_structp png_ptr)
+png_get_mem_ptr(png_const_structrp png_ptr)
 {
    if (png_ptr == NULL)
-      return (NULL);
+      return NULL;
 
-   return ((png_voidp)png_ptr->mem_ptr);
+   return png_ptr->mem_ptr;
 }
-#endif /* PNG_USER_MEM_SUPPORTED */
-#endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */
+#endif /* USER_MEM */
+#endif /* READ || WRITE */
diff --git a/src/3rdparty/libpng/pngpread.c b/src/3rdparty/libpng/pngpread.c
index 8a5aa29..823dcad 100644
--- a/src/3rdparty/libpng/pngpread.c
+++ b/src/3rdparty/libpng/pngpread.c
@@ -1,8 +1,8 @@
 
 /* pngpread.c - read a png file in push mode
  *
- * Last changed in libpng 1.5.9 [February 18, 2012]
- * Copyright (c) 1998-2012 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.17 [March 26, 2015]
+ * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
@@ -26,8 +26,15 @@
 #define PNG_READ_iTXt_MODE  7
 #define PNG_ERROR_MODE      8
 
+#define PNG_PUSH_SAVE_BUFFER_IF_FULL \
+if (png_ptr->push_length + 4 > png_ptr->buffer_size) \
+   { png_push_save_buffer(png_ptr); return; }
+#define PNG_PUSH_SAVE_BUFFER_IF_LT(N) \
+if (png_ptr->buffer_size < N) \
+   { png_push_save_buffer(png_ptr); return; }
+
 void PNGAPI
-png_process_data(png_structp png_ptr, png_infop info_ptr,
+png_process_data(png_structrp png_ptr, png_inforp info_ptr,
     png_bytep buffer, png_size_t buffer_size)
 {
    if (png_ptr == NULL || info_ptr == NULL)
@@ -42,14 +49,14 @@ png_process_data(png_structp png_ptr, png_infop info_ptr,
 }
 
 png_size_t PNGAPI
-png_process_data_pause(png_structp png_ptr, int save)
+png_process_data_pause(png_structrp png_ptr, int save)
 {
    if (png_ptr != NULL)
    {
-      /* It's easiest for the caller if we do the save, then the caller doesn't
+      /* It's easiest for the caller if we do the save; then the caller doesn't
        * have to supply the same data again:
        */
-      if (save)
+      if (save != 0)
          png_push_save_buffer(png_ptr);
       else
       {
@@ -69,7 +76,7 @@ png_process_data_pause(png_structp png_ptr, int save)
 }
 
 png_uint_32 PNGAPI
-png_process_data_skip(png_structp png_ptr)
+png_process_data_skip(png_structrp png_ptr)
 {
    png_uint_32 remaining = 0;
 
@@ -103,7 +110,7 @@ png_process_data_skip(png_structp png_ptr)
  * doing before we ran out of data...
  */
 void /* PRIVATE */
-png_process_some_data(png_structp png_ptr, png_infop info_ptr)
+png_process_some_data(png_structrp png_ptr, png_inforp info_ptr)
 {
    if (png_ptr == NULL)
       return;
@@ -149,10 +156,10 @@ png_process_some_data(png_structp png_ptr, png_infop info_ptr)
  * routine.
  */
 void /* PRIVATE */
-png_push_read_sig(png_structp png_ptr, png_infop info_ptr)
+png_push_read_sig(png_structrp png_ptr, png_inforp info_ptr)
 {
-   png_size_t num_checked = png_ptr->sig_bytes,
-       num_to_check = 8 - num_checked;
+   png_size_t num_checked = png_ptr->sig_bytes, /* SAFE, does not exceed 8 */ 
+             num_to_check = 8 - num_checked;
 
    if (png_ptr->buffer_size < num_to_check)
    {
@@ -172,7 +179,6 @@ png_push_read_sig(png_structp png_ptr, png_infop info_ptr)
       else
          png_error(png_ptr, "PNG file corrupted by ASCII conversion");
    }
-
    else
    {
       if (png_ptr->sig_bytes >= 8)
@@ -183,27 +189,25 @@ png_push_read_sig(png_structp png_ptr, png_infop info_ptr)
 }
 
 void /* PRIVATE */
-png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
+png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr)
 {
    png_uint_32 chunk_name;
+#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+   int keep; /* unknown handling method */
+#endif
 
-   /* First we make sure we have enough data for the 4 byte chunk name
-    * and the 4 byte chunk length before proceeding with decoding the
+   /* First we make sure we have enough data for the 4-byte chunk name
+    * and the 4-byte chunk length before proceeding with decoding the
     * chunk data.  To fully decode each of these chunks, we also make
-    * sure we have enough data in the buffer for the 4 byte CRC at the
+    * sure we have enough data in the buffer for the 4-byte CRC at the
     * end of every chunk (except IDAT, which is handled separately).
     */
-   if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))
+   if ((png_ptr->mode & PNG_HAVE_CHUNK_HEADER) == 0)
    {
       png_byte chunk_length[4];
       png_byte chunk_tag[4];
 
-      if (png_ptr->buffer_size < 8)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_LT(8)
       png_push_fill_buffer(png_ptr, chunk_length, 4);
       png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
       png_reset_crc(png_ptr);
@@ -217,14 +221,29 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 
    if (chunk_name == png_IDAT)
    {
-      /* This is here above the if/else case statement below because if the
-       * unknown handling marks 'IDAT' as unknown then the IDAT handling case is
-       * completely skipped.
-       *
-       * TODO: there must be a better way of doing this.
-       */
-      if (png_ptr->mode & PNG_AFTER_IDAT)
+      if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
          png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
+
+      /* If we reach an IDAT chunk, this means we have read all of the
+       * header chunks, and we can start reading the image (or if this
+       * is called after the image has been read - we have an error).
+       */
+      if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
+         png_error(png_ptr, "Missing IHDR before IDAT");
+
+      else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
+          (png_ptr->mode & PNG_HAVE_PLTE) == 0)
+         png_error(png_ptr, "Missing PLTE before IDAT");
+
+      png_ptr->mode |= PNG_HAVE_IDAT;
+      png_ptr->process_mode = PNG_READ_IDAT_MODE;
+
+      if ((png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) == 0)
+         if (png_ptr->push_length == 0)
+            return;
+
+      if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
+         png_benign_error(png_ptr, "Too many IDATs found");
    }
 
    if (chunk_name == png_IHDR)
@@ -232,23 +251,13 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
       if (png_ptr->push_length != 13)
          png_error(png_ptr, "Invalid IHDR length");
 
-      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_FULL
       png_handle_IHDR(png_ptr, info_ptr, png_ptr->push_length);
    }
 
    else if (chunk_name == png_IEND)
    {
-      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_FULL
       png_handle_IEND(png_ptr, info_ptr, png_ptr->push_length);
 
       png_ptr->process_mode = PNG_READ_DONE_MODE;
@@ -256,70 +265,25 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
    }
 
 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
-   else if (png_chunk_unknown_handling(png_ptr, chunk_name))
+   else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
    {
-      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
-      if (chunk_name == png_IDAT)
-         png_ptr->mode |= PNG_HAVE_IDAT;
-
-      png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length);
+      PNG_PUSH_SAVE_BUFFER_IF_FULL
+      png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length, keep);
 
       if (chunk_name == png_PLTE)
          png_ptr->mode |= PNG_HAVE_PLTE;
-
-      else if (chunk_name == png_IDAT)
-      {
-         if (!(png_ptr->mode & PNG_HAVE_IHDR))
-            png_error(png_ptr, "Missing IHDR before IDAT");
-
-         else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
-             !(png_ptr->mode & PNG_HAVE_PLTE))
-            png_error(png_ptr, "Missing PLTE before IDAT");
-      }
    }
-
 #endif
+
    else if (chunk_name == png_PLTE)
    {
-      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
+      PNG_PUSH_SAVE_BUFFER_IF_FULL
       png_handle_PLTE(png_ptr, info_ptr, png_ptr->push_length);
    }
 
    else if (chunk_name == png_IDAT)
    {
-      /* If we reach an IDAT chunk, this means we have read all of the
-       * header chunks, and we can start reading the image (or if this
-       * is called after the image has been read - we have an error).
-       */
-
-      if (!(png_ptr->mode & PNG_HAVE_IHDR))
-         png_error(png_ptr, "Missing IHDR before IDAT");
-
-      else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
-          !(png_ptr->mode & PNG_HAVE_PLTE))
-         png_error(png_ptr, "Missing PLTE before IDAT");
-
-      if (png_ptr->mode & PNG_HAVE_IDAT)
-      {
-         if (!(png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
-            if (png_ptr->push_length == 0)
-               return;
-
-         if (png_ptr->mode & PNG_AFTER_IDAT)
-            png_benign_error(png_ptr, "Too many IDATs found");
-      }
-
       png_ptr->idat_size = png_ptr->push_length;
-      png_ptr->mode |= PNG_HAVE_IDAT;
       png_ptr->process_mode = PNG_READ_IDAT_MODE;
       png_push_have_info(png_ptr, info_ptr);
       png_ptr->zstream.avail_out =
@@ -332,12 +296,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 #ifdef PNG_READ_gAMA_SUPPORTED
    else if (png_ptr->chunk_name == png_gAMA)
    {
-      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_FULL
       png_handle_gAMA(png_ptr, info_ptr, png_ptr->push_length);
    }
 
@@ -345,12 +304,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 #ifdef PNG_READ_sBIT_SUPPORTED
    else if (png_ptr->chunk_name == png_sBIT)
    {
-      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_FULL
       png_handle_sBIT(png_ptr, info_ptr, png_ptr->push_length);
    }
 
@@ -358,12 +312,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 #ifdef PNG_READ_cHRM_SUPPORTED
    else if (png_ptr->chunk_name == png_cHRM)
    {
-      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_FULL
       png_handle_cHRM(png_ptr, info_ptr, png_ptr->push_length);
    }
 
@@ -371,12 +320,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 #ifdef PNG_READ_sRGB_SUPPORTED
    else if (chunk_name == png_sRGB)
    {
-      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_FULL
       png_handle_sRGB(png_ptr, info_ptr, png_ptr->push_length);
    }
 
@@ -384,12 +328,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 #ifdef PNG_READ_iCCP_SUPPORTED
    else if (png_ptr->chunk_name == png_iCCP)
    {
-      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_FULL
       png_handle_iCCP(png_ptr, info_ptr, png_ptr->push_length);
    }
 
@@ -397,12 +336,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 #ifdef PNG_READ_sPLT_SUPPORTED
    else if (chunk_name == png_sPLT)
    {
-      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_FULL
       png_handle_sPLT(png_ptr, info_ptr, png_ptr->push_length);
    }
 
@@ -410,12 +344,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 #ifdef PNG_READ_tRNS_SUPPORTED
    else if (chunk_name == png_tRNS)
    {
-      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_FULL
       png_handle_tRNS(png_ptr, info_ptr, png_ptr->push_length);
    }
 
@@ -423,12 +352,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 #ifdef PNG_READ_bKGD_SUPPORTED
    else if (chunk_name == png_bKGD)
    {
-      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_FULL
       png_handle_bKGD(png_ptr, info_ptr, png_ptr->push_length);
    }
 
@@ -436,12 +360,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 #ifdef PNG_READ_hIST_SUPPORTED
    else if (chunk_name == png_hIST)
    {
-      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_FULL
       png_handle_hIST(png_ptr, info_ptr, png_ptr->push_length);
    }
 
@@ -449,12 +368,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 #ifdef PNG_READ_pHYs_SUPPORTED
    else if (chunk_name == png_pHYs)
    {
-      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_FULL
       png_handle_pHYs(png_ptr, info_ptr, png_ptr->push_length);
    }
 
@@ -462,12 +376,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 #ifdef PNG_READ_oFFs_SUPPORTED
    else if (chunk_name == png_oFFs)
    {
-      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_FULL
       png_handle_oFFs(png_ptr, info_ptr, png_ptr->push_length);
    }
 #endif
@@ -475,12 +384,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 #ifdef PNG_READ_pCAL_SUPPORTED
    else if (chunk_name == png_pCAL)
    {
-      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_FULL
       png_handle_pCAL(png_ptr, info_ptr, png_ptr->push_length);
    }
 
@@ -488,12 +392,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 #ifdef PNG_READ_sCAL_SUPPORTED
    else if (chunk_name == png_sCAL)
    {
-      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_FULL
       png_handle_sCAL(png_ptr, info_ptr, png_ptr->push_length);
    }
 
@@ -501,12 +400,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 #ifdef PNG_READ_tIME_SUPPORTED
    else if (chunk_name == png_tIME)
    {
-      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_FULL
       png_handle_tIME(png_ptr, info_ptr, png_ptr->push_length);
    }
 
@@ -514,12 +408,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 #ifdef PNG_READ_tEXt_SUPPORTED
    else if (chunk_name == png_tEXt)
    {
-      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_FULL
       png_handle_tEXt(png_ptr, info_ptr, png_ptr->push_length);
    }
 
@@ -527,12 +416,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 #ifdef PNG_READ_zTXt_SUPPORTED
    else if (chunk_name == png_zTXt)
    {
-      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_FULL
       png_handle_zTXt(png_ptr, info_ptr, png_ptr->push_length);
    }
 
@@ -540,40 +424,32 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 #ifdef PNG_READ_iTXt_SUPPORTED
    else if (chunk_name == png_iTXt)
    {
-      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_FULL
       png_handle_iTXt(png_ptr, info_ptr, png_ptr->push_length);
    }
-
 #endif
+
    else
    {
-      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-      png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length);
+      PNG_PUSH_SAVE_BUFFER_IF_FULL
+      png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length,
+         PNG_HANDLE_CHUNK_AS_DEFAULT);
    }
 
    png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
 }
 
 void /* PRIVATE */
-png_push_crc_skip(png_structp png_ptr, png_uint_32 skip)
+png_push_crc_skip(png_structrp png_ptr, png_uint_32 skip)
 {
    png_ptr->process_mode = PNG_SKIP_MODE;
    png_ptr->skip_length = skip;
 }
 
 void /* PRIVATE */
-png_push_crc_finish(png_structp png_ptr)
+png_push_crc_finish(png_structrp png_ptr)
 {
-   if (png_ptr->skip_length && png_ptr->save_buffer_size)
+   if (png_ptr->skip_length != 0 && png_ptr->save_buffer_size != 0)
    {
       png_size_t save_size = png_ptr->save_buffer_size;
       png_uint_32 skip_length = png_ptr->skip_length;
@@ -597,8 +473,7 @@ png_push_crc_finish(png_structp png_ptr)
       png_ptr->save_buffer_size -= save_size;
       png_ptr->save_buffer_ptr += save_size;
    }
-
-   if (png_ptr->skip_length && png_ptr->current_buffer_size)
+   if (png_ptr->skip_length != 0 && png_ptr->current_buffer_size != 0)
    {
       png_size_t save_size = png_ptr->current_buffer_size;
       png_uint_32 skip_length = png_ptr->skip_length;
@@ -619,15 +494,9 @@ png_push_crc_finish(png_structp png_ptr)
       png_ptr->current_buffer_size -= save_size;
       png_ptr->current_buffer_ptr += save_size;
    }
-
-   if (!png_ptr->skip_length)
+   if (png_ptr->skip_length == 0)
    {
-      if (png_ptr->buffer_size < 4)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_LT(4)
       png_crc_finish(png_ptr, 0);
       png_ptr->process_mode = PNG_READ_CHUNK_MODE;
    }
@@ -642,8 +511,7 @@ png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)
       return;
 
    ptr = buffer;
-
-   if (png_ptr->save_buffer_size)
+   if (png_ptr->save_buffer_size != 0)
    {
       png_size_t save_size;
 
@@ -653,15 +521,14 @@ png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)
       else
          save_size = png_ptr->save_buffer_size;
 
-      png_memcpy(ptr, png_ptr->save_buffer_ptr, save_size);
+      memcpy(ptr, png_ptr->save_buffer_ptr, save_size);
       length -= save_size;
       ptr += save_size;
       png_ptr->buffer_size -= save_size;
       png_ptr->save_buffer_size -= save_size;
       png_ptr->save_buffer_ptr += save_size;
    }
-
-   if (length && png_ptr->current_buffer_size)
+   if (length != 0 && png_ptr->current_buffer_size != 0)
    {
       png_size_t save_size;
 
@@ -671,7 +538,7 @@ png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)
       else
          save_size = png_ptr->current_buffer_size;
 
-      png_memcpy(ptr, png_ptr->current_buffer_ptr, save_size);
+      memcpy(ptr, png_ptr->current_buffer_ptr, save_size);
       png_ptr->buffer_size -= save_size;
       png_ptr->current_buffer_size -= save_size;
       png_ptr->current_buffer_ptr += save_size;
@@ -679,9 +546,9 @@ png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)
 }
 
 void /* PRIVATE */
-png_push_save_buffer(png_structp png_ptr)
+png_push_save_buffer(png_structrp png_ptr)
 {
-   if (png_ptr->save_buffer_size)
+   if (png_ptr->save_buffer_size != 0)
    {
       if (png_ptr->save_buffer_ptr != png_ptr->save_buffer)
       {
@@ -690,7 +557,6 @@ png_push_save_buffer(png_structp png_ptr)
          png_bytep dp;
 
          istop = png_ptr->save_buffer_size;
-
          for (i = 0, sp = png_ptr->save_buffer_ptr, dp = png_ptr->save_buffer;
              i < istop; i++, sp++, dp++)
          {
@@ -698,7 +564,6 @@ png_push_save_buffer(png_structp png_ptr)
          }
       }
    }
-
    if (png_ptr->save_buffer_size + png_ptr->current_buffer_size >
        png_ptr->save_buffer_max)
    {
@@ -713,33 +578,34 @@ png_push_save_buffer(png_structp png_ptr)
 
       new_max = png_ptr->save_buffer_size + png_ptr->current_buffer_size + 256;
       old_buffer = png_ptr->save_buffer;
-      png_ptr->save_buffer = (png_bytep)png_malloc_warn(png_ptr, new_max);
+      png_ptr->save_buffer = (png_bytep)png_malloc_warn(png_ptr,
+          (png_size_t)new_max);
 
       if (png_ptr->save_buffer == NULL)
       {
          png_free(png_ptr, old_buffer);
+         old_buffer = NULL;
          png_error(png_ptr, "Insufficient memory for save_buffer");
       }
 
-      png_memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size);
+      memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size);
       png_free(png_ptr, old_buffer);
+      old_buffer = NULL;
       png_ptr->save_buffer_max = new_max;
    }
-
    if (png_ptr->current_buffer_size)
    {
-      png_memcpy(png_ptr->save_buffer + png_ptr->save_buffer_size,
+      memcpy(png_ptr->save_buffer + png_ptr->save_buffer_size,
          png_ptr->current_buffer_ptr, png_ptr->current_buffer_size);
       png_ptr->save_buffer_size += png_ptr->current_buffer_size;
       png_ptr->current_buffer_size = 0;
    }
-
    png_ptr->save_buffer_ptr = png_ptr->save_buffer;
    png_ptr->buffer_size = 0;
 }
 
 void /* PRIVATE */
-png_push_restore_buffer(png_structp png_ptr, png_bytep buffer,
+png_push_restore_buffer(png_structrp png_ptr, png_bytep buffer,
    png_size_t buffer_length)
 {
    png_ptr->current_buffer = buffer;
@@ -749,20 +615,15 @@ png_push_restore_buffer(png_structp png_ptr, png_bytep buffer,
 }
 
 void /* PRIVATE */
-png_push_read_IDAT(png_structp png_ptr)
+png_push_read_IDAT(png_structrp png_ptr)
 {
-   if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))
+   if ((png_ptr->mode & PNG_HAVE_CHUNK_HEADER) == 0)
    {
       png_byte chunk_length[4];
       png_byte chunk_tag[4];
 
       /* TODO: this code can be commoned up with the same code in push_read */
-      if (png_ptr->buffer_size < 8)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_LT(8)
       png_push_fill_buffer(png_ptr, chunk_length, 4);
       png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
       png_reset_crc(png_ptr);
@@ -774,7 +635,7 @@ png_push_read_IDAT(png_structp png_ptr)
       {
          png_ptr->process_mode = PNG_READ_CHUNK_MODE;
 
-         if (!(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
+         if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
             png_error(png_ptr, "Not enough compressed data");
 
          return;
@@ -783,7 +644,7 @@ png_push_read_IDAT(png_structp png_ptr)
       png_ptr->idat_size = png_ptr->push_length;
    }
 
-   if (png_ptr->idat_size && png_ptr->save_buffer_size)
+   if (png_ptr->idat_size != 0 && png_ptr->save_buffer_size != 0)
    {
       png_size_t save_size = png_ptr->save_buffer_size;
       png_uint_32 idat_size = png_ptr->idat_size;
@@ -810,7 +671,7 @@ png_push_read_IDAT(png_structp png_ptr)
       png_ptr->save_buffer_ptr += save_size;
    }
 
-   if (png_ptr->idat_size && png_ptr->current_buffer_size)
+   if (png_ptr->idat_size != 0 && png_ptr->current_buffer_size != 0)
    {
       png_size_t save_size = png_ptr->current_buffer_size;
       png_uint_32 idat_size = png_ptr->idat_size;
@@ -835,23 +696,18 @@ png_push_read_IDAT(png_structp png_ptr)
       png_ptr->current_buffer_size -= save_size;
       png_ptr->current_buffer_ptr += save_size;
    }
-
-   if (!png_ptr->idat_size)
+   if (png_ptr->idat_size == 0)
    {
-      if (png_ptr->buffer_size < 4)
-      {
-         png_push_save_buffer(png_ptr);
-         return;
-      }
-
+      PNG_PUSH_SAVE_BUFFER_IF_LT(4)
       png_crc_finish(png_ptr, 0);
       png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
       png_ptr->mode |= PNG_AFTER_IDAT;
+      png_ptr->zowner = 0;
    }
 }
 
 void /* PRIVATE */
-png_process_IDAT_data(png_structp png_ptr, png_bytep buffer,
+png_process_IDAT_data(png_structrp png_ptr, png_bytep buffer,
    png_size_t buffer_length)
 {
    /* The caller checks for a non-zero buffer length. */
@@ -863,13 +719,14 @@ png_process_IDAT_data(png_structp png_ptr, png_bytep buffer,
     * handle the uncompressed results.
     */
    png_ptr->zstream.next_in = buffer;
+   /* TODO: WARNING: TRUNCATION ERROR: DANGER WILL ROBINSON: */
    png_ptr->zstream.avail_in = (uInt)buffer_length;
 
    /* Keep going until the decompressed data is all processed
     * or the stream marked as finished.
     */
    while (png_ptr->zstream.avail_in > 0 &&
-          !(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
+      (png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
    {
       int ret;
 
@@ -880,9 +737,9 @@ png_process_IDAT_data(png_structp png_ptr, png_bytep buffer,
        */
       if (!(png_ptr->zstream.avail_out > 0))
       {
-         png_ptr->zstream.avail_out =
-             (uInt) PNG_ROWBYTES(png_ptr->pixel_depth,
-             png_ptr->iwidth) + 1;
+         /* TODO: WARNING: TRUNCATION ERROR: DANGER WILL ROBINSON: */
+         png_ptr->zstream.avail_out = (uInt)(PNG_ROWBYTES(png_ptr->pixel_depth,
+             png_ptr->iwidth) + 1);
 
          png_ptr->zstream.next_out = png_ptr->row_buf;
       }
@@ -900,7 +757,8 @@ png_process_IDAT_data(png_structp png_ptr, png_bytep buffer,
       if (ret != Z_OK && ret != Z_STREAM_END)
       {
          /* Terminate the decompression. */
-         png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
+         png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
+         png_ptr->zowner = 0;
 
          /* This may be a truncated stream (missing or
           * damaged end code).  Treat that as a warning.
@@ -928,7 +786,8 @@ png_process_IDAT_data(png_structp png_ptr, png_bytep buffer,
          {
             /* Extra data. */
             png_warning(png_ptr, "Extra compressed data in IDAT");
-            png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
+            png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
+            png_ptr->zowner = 0;
 
             /* Do no more processing; skip the unprocessed
              * input check below.
@@ -943,7 +802,7 @@ png_process_IDAT_data(png_structp png_ptr, png_bytep buffer,
 
       /* And check for the end of the stream. */
       if (ret == Z_STREAM_END)
-         png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
+         png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
    }
 
    /* All the data should have been processed, if anything
@@ -955,7 +814,7 @@ png_process_IDAT_data(png_structp png_ptr, png_bytep buffer,
 }
 
 void /* PRIVATE */
-png_push_process_row(png_structp png_ptr)
+png_push_process_row(png_structrp png_ptr)
 {
    /* 1.5.6: row_info moved out of png_struct to a local here. */
    png_row_info row_info;
@@ -981,10 +840,10 @@ png_push_process_row(png_structp png_ptr)
     * it may not be in the future, so this was changed just to copy the
     * interlaced row count:
     */
-   png_memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
+   memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
 
 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
-   if (png_ptr->transformations)
+   if (png_ptr->transformations != 0)
       png_do_read_transformations(png_ptr, &row_info);
 #endif
 
@@ -1001,15 +860,16 @@ png_push_process_row(png_structp png_ptr)
 
 
 #ifdef PNG_READ_INTERLACING_SUPPORTED
-   /* Blow up interlaced rows to full size */
-   if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
+   /* Expand interlaced rows to full size */
+   if (png_ptr->interlaced != 0 &&
+       (png_ptr->transformations & PNG_INTERLACE) != 0)
    {
       if (png_ptr->pass < 6)
          png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
             png_ptr->transformations);
 
-    switch (png_ptr->pass)
-    {
+      switch (png_ptr->pass)
+      {
          case 0:
          {
             int i;
@@ -1184,26 +1044,26 @@ png_push_process_row(png_structp png_ptr)
 }
 
 void /* PRIVATE */
-png_read_push_finish_row(png_structp png_ptr)
+png_read_push_finish_row(png_structrp png_ptr)
 {
 #ifdef PNG_READ_INTERLACING_SUPPORTED
    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
 
    /* Start of interlace block */
-   static PNG_CONST png_byte FARDATA png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
+   static PNG_CONST png_byte png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
 
    /* Offset to next interlace block */
-   static PNG_CONST png_byte FARDATA png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
+   static PNG_CONST png_byte png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
 
    /* Start of interlace block in the y direction */
-   static PNG_CONST png_byte FARDATA png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
+   static PNG_CONST png_byte png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
 
    /* Offset to next interlace block in the y direction */
-   static PNG_CONST png_byte FARDATA png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
+   static PNG_CONST png_byte png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
 
    /* Height of interlace block.  This is not currently used - if you need
     * it, uncomment it here and in png.h
-   static PNG_CONST png_byte FARDATA png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
+   static PNG_CONST png_byte png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
    */
 #endif
 
@@ -1212,10 +1072,10 @@ png_read_push_finish_row(png_structp png_ptr)
       return;
 
 #ifdef PNG_READ_INTERLACING_SUPPORTED
-   if (png_ptr->interlaced)
+   if (png_ptr->interlaced != 0)
    {
       png_ptr->row_number = 0;
-      png_memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
+      memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
 
       do
       {
@@ -1236,7 +1096,7 @@ png_read_push_finish_row(png_structp png_ptr)
              png_pass_start[png_ptr->pass]) /
              png_pass_inc[png_ptr->pass];
 
-         if (png_ptr->transformations & PNG_INTERLACE)
+         if ((png_ptr->transformations & PNG_INTERLACE) != 0)
             break;
 
          png_ptr->num_rows = (png_ptr->height +
@@ -1246,25 +1106,25 @@ png_read_push_finish_row(png_structp png_ptr)
 
       } while (png_ptr->iwidth == 0 || png_ptr->num_rows == 0);
    }
-#endif /* PNG_READ_INTERLACING_SUPPORTED */
+#endif /* READ_INTERLACING */
 }
 
 void /* PRIVATE */
-png_push_have_info(png_structp png_ptr, png_infop info_ptr)
+png_push_have_info(png_structrp png_ptr, png_inforp info_ptr)
 {
    if (png_ptr->info_fn != NULL)
       (*(png_ptr->info_fn))(png_ptr, info_ptr);
 }
 
 void /* PRIVATE */
-png_push_have_end(png_structp png_ptr, png_infop info_ptr)
+png_push_have_end(png_structrp png_ptr, png_inforp info_ptr)
 {
    if (png_ptr->end_fn != NULL)
       (*(png_ptr->end_fn))(png_ptr, info_ptr);
 }
 
 void /* PRIVATE */
-png_push_have_row(png_structp png_ptr, png_bytep row)
+png_push_have_row(png_structrp png_ptr, png_bytep row)
 {
    if (png_ptr->row_fn != NULL)
       (*(png_ptr->row_fn))(png_ptr, row, png_ptr->row_number,
@@ -1273,7 +1133,7 @@ png_push_have_row(png_structp png_ptr, png_bytep row)
 
 #ifdef PNG_READ_INTERLACING_SUPPORTED
 void PNGAPI
-png_progressive_combine_row (png_structp png_ptr, png_bytep old_row,
+png_progressive_combine_row(png_const_structrp png_ptr, png_bytep old_row,
     png_const_bytep new_row)
 {
    if (png_ptr == NULL)
@@ -1284,12 +1144,12 @@ png_progressive_combine_row (png_structp png_ptr, png_bytep old_row,
     * it must be png_ptr->row_buf+1
     */
    if (new_row != NULL)
-      png_combine_row(png_ptr, old_row, 1/*display*/);
+      png_combine_row(png_ptr, old_row, 1/*blocky display*/);
 }
-#endif /* PNG_READ_INTERLACING_SUPPORTED */
+#endif /* READ_INTERLACING */
 
 void PNGAPI
-png_set_progressive_read_fn(png_structp png_ptr, png_voidp progressive_ptr,
+png_set_progressive_read_fn(png_structrp png_ptr, png_voidp progressive_ptr,
     png_progressive_info_ptr info_fn, png_progressive_row_ptr row_fn,
     png_progressive_end_ptr end_fn)
 {
@@ -1304,11 +1164,11 @@ png_set_progressive_read_fn(png_structp png_ptr, png_voidp progressive_ptr,
 }
 
 png_voidp PNGAPI
-png_get_progressive_ptr(png_const_structp png_ptr)
+png_get_progressive_ptr(png_const_structrp png_ptr)
 {
    if (png_ptr == NULL)
       return (NULL);
 
    return png_ptr->io_ptr;
 }
-#endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
+#endif /* PROGRESSIVE_READ */
diff --git a/src/3rdparty/libpng/pngpriv.h b/src/3rdparty/libpng/pngpriv.h
index dd8c9b9..4031d73 100644
--- a/src/3rdparty/libpng/pngpriv.h
+++ b/src/3rdparty/libpng/pngpriv.h
@@ -1,20 +1,18 @@
 
 /* pngpriv.h - private declarations for use inside libpng
  *
- * For conditions of distribution and use, see copyright notice in png.h
- * Copyright (c) 1998-2012 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.17 [March 26, 2015]
+ * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
- * Last changed in libpng 1.5.10 [March 29, 2012]
- *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
  * and license in png.h
  */
 
 /* The symbols declared in this file (including the functions declared
- * as PNG_EXTERN) are PRIVATE.  They are not part of the libpng public
+ * as extern) are PRIVATE.  They are not part of the libpng public
  * interface, and are not recommended for use by regular applications.
  * Some of them may become public in the future; others may stay private,
  * change in an incompatible way, or even disappear.
@@ -45,15 +43,43 @@
  */
 #define _POSIX_SOURCE 1 /* Just the POSIX 1003.1 and C89 APIs */
 
-/* This is required for the definition of abort(), used as a last ditch
- * error handler when all else fails.
+#ifndef PNG_VERSION_INFO_ONLY
+/* Standard library headers not required by png.h: */
+#  include <stdlib.h>
+#  include <string.h>
+#endif
+
+#define PNGLIB_BUILD /*libpng is being built, not used*/
+
+/* If HAVE_CONFIG_H is defined during the build then the build system must
+ * provide an appropriate "config.h" file on the include path.  The header file
+ * must provide definitions as required below (search for "HAVE_CONFIG_H");
+ * see configure.ac for more details of the requirements.  The macro
+ * "PNG_NO_CONFIG_H" is provided for maintainers to test for dependencies on
+ * 'configure'; define this macro to prevent the configure build including the
+ * configure generated config.h.  Libpng is expected to compile without *any*
+ * special build system support on a reasonably ANSI-C compliant system.
  */
-#include <stdlib.h>
+#if defined(HAVE_CONFIG_H) && !defined(PNG_NO_CONFIG_H)
+#  include <config.h>
 
-/* This is used to find 'offsetof', used below for alignment tests. */
-#include <stddef.h>
+   /* Pick up the definition of 'restrict' from config.h if it was read: */
+#  define PNG_RESTRICT restrict
+#endif
 
-#define PNGLIB_BUILD /*libpng is being built, not used*/
+/* To support symbol prefixing it is necessary to know *before* including png.h
+ * whether the fixed point (and maybe other) APIs are exported, because if they
+ * are not internal definitions may be required.  This is handled below just
+ * before png.h is included, but load the configuration now if it is available.
+ */
+#ifndef PNGLCONF_H
+#  include "pnglibconf.h"
+#endif
+
+/* Local renames may change non-exported API functions from png.h */
+#if defined(PNG_PREFIX) && !defined(PNGPREFIX_H)
+#  include "pngprefix.h"
+#endif
 
 #ifdef PNG_USER_CONFIG
 #  include "pngusr.h"
@@ -66,6 +92,98 @@
 #  endif
 #endif
 
+/* Compile time options.
+ * =====================
+ * In a multi-arch build the compiler may compile the code several times for the
+ * same object module, producing different binaries for different architectures.
+ * When this happens configure-time setting of the target host options cannot be
+ * done and this interferes with the handling of the ARM NEON optimizations, and
+ * possibly other similar optimizations.  Put additional tests here; in general
+ * this is needed when the same option can be changed at both compile time and
+ * run time depending on the target OS (i.e. iOS vs Android.)
+ *
+ * NOTE: symbol prefixing does not pass $(CFLAGS) to the preprocessor, because
+ * this is not possible with certain compilers (Oracle SUN OS CC), as a result
+ * it is necessary to ensure that all extern functions that *might* be used
+ * regardless of $(CFLAGS) get declared in this file.  The test on __ARM_NEON__
+ * below is one example of this behavior because it is controlled by the
+ * presence or not of -mfpu=neon on the GCC command line, it is possible to do
+ * this in $(CC), e.g. "CC=gcc -mfpu=neon", but people who build libpng rarely
+ * do this.
+ */
+#ifndef PNG_ARM_NEON_OPT
+   /* ARM NEON optimizations are being controlled by the compiler settings,
+    * typically the target FPU.  If the FPU has been set to NEON (-mfpu=neon
+    * with GCC) then the compiler will define __ARM_NEON__ and we can rely
+    * unconditionally on NEON instructions not crashing, otherwise we must
+    * disable use of NEON instructions.
+    *
+    * NOTE: at present these optimizations depend on 'ALIGNED_MEMORY', so they
+    * can only be turned on automatically if that is supported too.  If
+    * PNG_ARM_NEON_OPT is set in CPPFLAGS (to >0) then arm/arm_init.c will fail
+    * to compile with an appropriate #error if ALIGNED_MEMORY has been turned
+    * off.
+    *
+    * Note that gcc-4.9 defines __ARM_NEON instead of __ARM_NEON__, so we
+    * check both variants.
+    */
+#  if (defined(__ARM_NEON__) || defined(__ARM_NEON)) && \
+   defined(PNG_ALIGNED_MEMORY_SUPPORTED)
+#     define PNG_ARM_NEON_OPT 2
+#  else
+#     define PNG_ARM_NEON_OPT 0
+#  endif
+#endif
+
+#if PNG_ARM_NEON_OPT > 0
+   /* NEON optimizations are to be at least considered by libpng, so enable the
+    * callbacks to do this.
+    */
+#  define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_neon
+
+   /* By default the 'intrinsics' code in arm/filter_neon_intrinsics.c is used
+    * if possible - if __ARM_NEON__ is set and the compiler version is not known
+    * to be broken.  This is controlled by PNG_ARM_NEON_IMPLEMENTATION which can
+    * be:
+    *
+    *    1  The intrinsics code (the default with __ARM_NEON__)
+    *    2  The hand coded assembler (the default without __ARM_NEON__)
+    *
+    * It is possible to set PNG_ARM_NEON_IMPLEMENTATION in CPPFLAGS, however
+    * this is *NOT* supported and may cease to work even after a minor revision
+    * to libpng.  It *is* valid to do this for testing purposes, e.g. speed
+    * testing or a new compiler, but the results should be communicated to the
+    * libpng implementation list for incorporation in the next minor release.
+    */
+#  ifndef PNG_ARM_NEON_IMPLEMENTATION
+#     if defined(__ARM_NEON__) || defined(__ARM_NEON)
+#        if defined(__clang__)
+            /* At present it is unknown by the libpng developers which versions
+             * of clang support the intrinsics, however some or perhaps all
+             * versions do not work with the assembler so this may be
+             * irrelevant, so just use the default (do nothing here.)
+             */
+#        elif defined(__GNUC__)
+            /* GCC 4.5.4 NEON support is known to be broken.  4.6.3 is known to
+             * work, so if this *is* GCC, or G++, look for a version >4.5
+             */
+#           if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 6)
+#              define PNG_ARM_NEON_IMPLEMENTATION 2
+#           endif /* no GNUC support */
+#        endif /* __GNUC__ */
+#     else /* !defined __ARM_NEON__ */
+         /* The 'intrinsics' code simply won't compile without this -mfpu=neon:
+          */
+#        define PNG_ARM_NEON_IMPLEMENTATION 2
+#     endif /* __ARM_NEON__ */
+#  endif /* !PNG_ARM_NEON_IMPLEMENTATION */
+
+#  ifndef PNG_ARM_NEON_IMPLEMENTATION
+      /* Use the intrinsics code by default. */
+#     define PNG_ARM_NEON_IMPLEMENTATION 1
+#  endif
+#endif /* PNG_ARM_NEON_OPT > 0 */
+
 /* Is this a build of a DLL where compilation of the object modules requires
  * different preprocessor settings to those required for a simple library?  If
  * so PNG_BUILD_DLL must be set.
@@ -135,76 +253,65 @@
 #  define PNG_PRIVATE
 #endif
 
-#include "png.h"
-#include "pnginfo.h"
-#include "pngstruct.h"
+/* Symbol preprocessing support.
+ *
+ * To enable listing global, but internal, symbols the following macros should
+ * always be used to declare an extern data or function object in this file.
+ */
+#ifndef PNG_INTERNAL_DATA
+#  define PNG_INTERNAL_DATA(type, name, array) extern type name array
+#endif
 
-/* pngconf.h does not set PNG_DLL_EXPORT unless it is required, so: */
-#ifndef PNG_DLL_EXPORT
-#  define PNG_DLL_EXPORT
+#ifndef PNG_INTERNAL_FUNCTION
+#  define PNG_INTERNAL_FUNCTION(type, name, args, attributes)\
+      extern PNG_FUNCTION(type, name, args, PNG_EMPTY attributes)
 #endif
 
-/* SECURITY and SAFETY:
+#ifndef PNG_INTERNAL_CALLBACK
+#  define PNG_INTERNAL_CALLBACK(type, name, args, attributes)\
+      extern PNG_FUNCTION(type, (PNGCBAPI name), args, PNG_EMPTY attributes)
+#endif
+
+/* If floating or fixed point APIs are disabled they may still be compiled
+ * internally.  To handle this make sure they are declared as the appropriate
+ * internal extern function (otherwise the symbol prefixing stuff won't work and
+ * the functions will be used without definitions.)
  *
- * By default libpng is built without any internal limits on image size,
- * individual heap (png_malloc) allocations or the total amount of memory used.
- * If PNG_SAFE_LIMITS_SUPPORTED is defined, however, the limits below are used
- * (unless individually overridden).  These limits are believed to be fairly
- * safe, but builders of secure systems should verify the values against the
- * real system capabilities.
- */
-
-#ifdef PNG_SAFE_LIMITS_SUPPORTED
-   /* 'safe' limits */
-#  ifndef PNG_USER_WIDTH_MAX
-#     define PNG_USER_WIDTH_MAX 1000000
-#  endif
-#  ifndef PNG_USER_HEIGHT_MAX
-#     define PNG_USER_HEIGHT_MAX 1000000
-#  endif
-#  ifndef PNG_USER_CHUNK_CACHE_MAX
-#     define PNG_USER_CHUNK_CACHE_MAX 128
-#  endif
-#  ifndef PNG_USER_CHUNK_MALLOC_MAX
-#     define PNG_USER_CHUNK_MALLOC_MAX 8000000
-#  endif
-#else
-   /* values for no limits */
-#  ifndef PNG_USER_WIDTH_MAX
-#     define PNG_USER_WIDTH_MAX 0x7fffffff
-#  endif
-#  ifndef PNG_USER_HEIGHT_MAX
-#     define PNG_USER_HEIGHT_MAX 0x7fffffff
-#  endif
-#  ifndef PNG_USER_CHUNK_CACHE_MAX
-#     define PNG_USER_CHUNK_CACHE_MAX 0
+ * NOTE: although all the API functions are declared here they are not all
+ * actually built!  Because the declarations are still made it is necessary to
+ * fake out types that they depend on.
+ */
+#ifndef PNG_FP_EXPORT
+#  ifndef PNG_FLOATING_POINT_SUPPORTED
+#     define PNG_FP_EXPORT(ordinal, type, name, args)\
+         PNG_INTERNAL_FUNCTION(type, name, args, PNG_EMPTY);
+#     ifndef PNG_VERSION_INFO_ONLY
+         typedef struct png_incomplete png_double;
+         typedef png_double*           png_doublep;
+         typedef const png_double*     png_const_doublep;
+         typedef png_double**          png_doublepp;
+#     endif
 #  endif
-#  ifndef PNG_USER_CHUNK_MALLOC_MAX
-#     define PNG_USER_CHUNK_MALLOC_MAX 0
+#endif
+#ifndef PNG_FIXED_EXPORT
+#  ifndef PNG_FIXED_POINT_SUPPORTED
+#     define PNG_FIXED_EXPORT(ordinal, type, name, args)\
+         PNG_INTERNAL_FUNCTION(type, name, args, PNG_EMPTY);
 #  endif
 #endif
 
-/* This is used for 16 bit gamma tables - only the top level pointers are const,
- * this could be changed:
- */
-typedef PNG_CONST png_uint_16p FAR * png_const_uint_16pp;
-
-/* Added at libpng-1.2.9 */
-/* Moved to pngpriv.h at libpng-1.5.0 */
+#include "png.h"
 
-/* config.h is created by and PNG_CONFIGURE_LIBPNG is set by the "configure"
- * script.  We may need it here to get the correct configuration on things
- * like limits.
- */
-#ifdef PNG_CONFIGURE_LIBPNG
-#  ifdef HAVE_CONFIG_H
-#    include "config.h"
-#  endif
+/* pngconf.h does not set PNG_DLL_EXPORT unless it is required, so: */
+#ifndef PNG_DLL_EXPORT
+#  define PNG_DLL_EXPORT
 #endif
 
-/* Moved to pngpriv.h at libpng-1.5.0 */
-/* NOTE: some of these may have been used in external applications as
- * these definitions were exposed in pngconf.h prior to 1.5.
+/* SECURITY and SAFETY:
+ *
+ * libpng is built with support for internal limits on image dimensions and
+ * memory usage.  These are documented in scripts/pnglibconf.dfa of the
+ * source and recorded in the machine generated header file pnglibconf.h.
  */
 
 /* If you are running on a machine where you cannot allocate more
@@ -240,30 +347,6 @@ typedef PNG_CONST png_uint_16p FAR * png_const_uint_16pp;
 #  define PNG_ZBUF_SIZE 65536L
 #endif
 
-/* PNG_STATIC is used to mark internal file scope functions if they need to be
- * accessed for implementation tests (see the code in tests/?*).
- */
-#ifndef PNG_STATIC
-#   define PNG_STATIC static
-#endif
-
-/* C99 restrict is used where possible, to do this 'restrict' is defined as
- * empty if we can't be sure it is supported.  configure builds have already
- * done this work.
- */
-#ifdef PNG_CONFIGURE_LIBPNG
-#  define PNG_RESTRICT restrict
-#else
-   /* Modern compilers support restrict, but assume not for anything not
-    * recognized here:
-    */
-#  if defined __GNUC__ || defined _MSC_VER || defined __WATCOMC__
-#     define PNG_RESTRICT restrict
-#  else
-#     define PNG_RESTRICT
-#  endif
-#endif
-
 /* If warnings or errors are turned off the code is disabled or redirected here.
  * From 1.5.4 functions have been added to allow very limited formatting of
  * error and warning messages - this code will also be disabled here.
@@ -271,8 +354,6 @@ typedef PNG_CONST png_uint_16p FAR * png_const_uint_16pp;
 #ifdef PNG_WARNINGS_SUPPORTED
 #  define PNG_WARNING_PARAMETERS(p) png_warning_parameters p;
 #else
-#  define png_warning(s1,s2) ((void)(s1))
-#  define png_chunk_warning(s1,s2) ((void)(s1))
 #  define png_warning_parameter(p,number,string) ((void)0)
 #  define png_warning_parameter_unsigned(p,number,format,value) ((void)0)
 #  define png_warning_parameter_signed(p,number,format,value) ((void)0)
@@ -280,8 +361,6 @@ typedef PNG_CONST png_uint_16p FAR * png_const_uint_16pp;
 #  define PNG_WARNING_PARAMETERS(p)
 #endif
 #ifndef PNG_ERROR_TEXT_SUPPORTED
-#  define png_error(s1,s2) png_err(s1)
-#  define png_chunk_error(s1,s2) png_err(s1)
 #  define png_fixed_error(s1,s2) png_err(s1)
 #endif
 
@@ -292,23 +371,18 @@ typedef PNG_CONST png_uint_16p FAR * png_const_uint_16pp;
  */
 #ifdef __cplusplus
 #  define png_voidcast(type, value) static_cast<type>(value)
+#  define png_constcast(type, value) const_cast<type>(value)
+#  define png_aligncast(type, value) \
+   static_cast<type>(static_cast<void*>(value))
+#  define png_aligncastconst(type, value) \
+   static_cast<type>(static_cast<const void*>(value))
 #else
 #  define png_voidcast(type, value) (value)
+#  define png_constcast(type, value) ((type)(value))
+#  define png_aligncast(type, value) ((void*)(value))
+#  define png_aligncastconst(type, value) ((const void*)(value))
 #endif /* __cplusplus */
 
-#ifndef PNG_EXTERN
-/* The functions exported by PNG_EXTERN are internal functions, which
- * aren't usually used outside the library (as far as I know), so it is
- * debatable if they should be exported at all.  In the future, when it
- * is possible to have run-time registry of chunk-handling functions,
- * some of these might be made available again.
- *
- * 1.5.7: turned the use of 'extern' back on, since it is localized to pngpriv.h
- * it should be safe now (it is unclear why it was turned off.)
- */
-#  define PNG_EXTERN extern
-#endif
-
 /* Some fixed point APIs are still required even if not exported because
  * they get used by the corresponding floating point APIs.  This magic
  * deals with this:
@@ -319,6 +393,7 @@ typedef PNG_CONST png_uint_16p FAR * png_const_uint_16pp;
 #  define PNGFAPI /* PRIVATE */
 #endif
 
+#ifndef PNG_VERSION_INFO_ONLY
 /* Other defines specific to compilers can go here.  Try to keep
  * them inside an appropriate ifdef/endif pair for portability.
  */
@@ -365,6 +440,7 @@ typedef PNG_CONST png_uint_16p FAR * png_const_uint_16pp;
 #    include <windows.h>  /* defines _WINDOWS_ macro */
 #  endif
 #endif
+#endif /* PNG_VERSION_INFO_ONLY */
 
 /* Moved here around 1.5.0beta36 from pngconf.h */
 /* Users may want to use these so they are not private.  Any library
@@ -380,34 +456,6 @@ typedef PNG_CONST png_uint_16p FAR * png_const_uint_16pp;
 #  endif
 #endif
 
-#ifdef USE_FAR_KEYWORD
-/* Use this to make far-to-near assignments */
-#  define CHECK   1
-#  define NOCHECK 0
-#  define CVT_PTR(ptr) (png_far_to_near(png_ptr,ptr,CHECK))
-#  define CVT_PTR_NOCHECK(ptr) (png_far_to_near(png_ptr,ptr,NOCHECK))
-#  define png_strlen  _fstrlen
-#  define png_memcmp  _fmemcmp    /* SJT: added */
-#  define png_memcpy  _fmemcpy
-#  define png_memset  _fmemset
-#else
-#  ifdef _WINDOWS_  /* Favor Windows over C runtime fns */
-#    define CVT_PTR(ptr)         (ptr)
-#    define CVT_PTR_NOCHECK(ptr) (ptr)
-#    define png_strlen  lstrlenA
-#    define png_memcmp  memcmp
-#    define png_memcpy  CopyMemory
-#    define png_memset  memset
-#  else
-#    define CVT_PTR(ptr)         (ptr)
-#    define CVT_PTR_NOCHECK(ptr) (ptr)
-#    define png_strlen  strlen
-#    define png_memcmp  memcmp      /* SJT: added */
-#    define png_memcpy  memcpy
-#    define png_memset  memset
-#  endif
-#endif
-
 /* These macros may need to be architecture dependent. */
 #define PNG_ALIGN_NONE   0 /* do not use data alignment */
 #define PNG_ALIGN_ALWAYS 1 /* assume unaligned accesses are OK */
@@ -429,7 +477,7 @@ typedef PNG_CONST png_uint_16p FAR * png_const_uint_16pp;
 #if PNG_ALIGN_TYPE == PNG_ALIGN_SIZE
    /* This is used because in some compiler implementations non-aligned
     * structure members are supported, so the offsetof approach below fails.
-    * Set PNG_ALIGN_TO_SIZE=0 for compiler combinations where unaligned access
+    * Set PNG_ALIGN_SIZE=0 for compiler combinations where unaligned access
     * is good for performance.  Do not do this unless you have tested the result
     * and understand it.
     */
@@ -470,16 +518,17 @@ typedef PNG_CONST png_uint_16p FAR * png_const_uint_16pp;
 #define PNG_HAVE_IDAT               0x04
 /* #define PNG_AFTER_IDAT           0x08 (defined in png.h) */
 #define PNG_HAVE_IEND               0x10
-#define PNG_HAVE_gAMA               0x20
-#define PNG_HAVE_cHRM               0x40
-#define PNG_HAVE_sRGB               0x80
+                   /*               0x20 (unused) */
+                   /*               0x40 (unused) */
+                   /*               0x80 (unused) */
 #define PNG_HAVE_CHUNK_HEADER      0x100
 #define PNG_WROTE_tIME             0x200
 #define PNG_WROTE_INFO_BEFORE_PLTE 0x400
 #define PNG_BACKGROUND_IS_GRAY     0x800
 #define PNG_HAVE_PNG_SIGNATURE    0x1000
 #define PNG_HAVE_CHUNK_AFTER_IDAT 0x2000 /* Have another chunk after IDAT */
-#define PNG_HAVE_iCCP             0x4000
+                   /*             0x4000 (unused) */
+#define PNG_IS_READ_STRUCT        0x8000 /* Else is a write struct */
 
 /* Flags for the transformations the PNG library does on the image data */
 #define PNG_BGR                 0x0001
@@ -507,13 +556,13 @@ typedef PNG_CONST png_uint_16p FAR * png_const_uint_16pp;
 #define PNG_RGB_TO_GRAY_WARN  0x400000
 #define PNG_RGB_TO_GRAY       0x600000 /* two bits, RGB_TO_GRAY_ERR|WARN */
 #define PNG_ENCODE_ALPHA      0x800000 /* Added to libpng-1.5.4 */
-#define PNG_ADD_ALPHA         0x1000000 /* Added to libpng-1.2.7 */
-#define PNG_EXPAND_tRNS       0x2000000 /* Added to libpng-1.2.9 */
-#define PNG_SCALE_16_TO_8     0x4000000 /* Added to libpng-1.5.4 */
-                       /*   0x8000000 unused */
-                       /*  0x10000000 unused */
-                       /*  0x20000000 unused */
-                       /*  0x40000000 unused */
+#define PNG_ADD_ALPHA        0x1000000 /* Added to libpng-1.2.7 */
+#define PNG_EXPAND_tRNS      0x2000000 /* Added to libpng-1.2.9 */
+#define PNG_SCALE_16_TO_8    0x4000000 /* Added to libpng-1.5.4 */
+                       /*    0x8000000 unused */
+                       /*   0x10000000 unused */
+                       /*   0x20000000 unused */
+                       /*   0x40000000 unused */
 /* Flags for png_create_struct */
 #define PNG_STRUCT_PNG   0x0001
 #define PNG_STRUCT_INFO  0x0002
@@ -524,36 +573,36 @@ typedef PNG_CONST png_uint_16p FAR * png_const_uint_16pp;
 
 /* Flags for the png_ptr->flags rather than declaring a byte for each one */
 #define PNG_FLAG_ZLIB_CUSTOM_STRATEGY     0x0001
-#define PNG_FLAG_ZLIB_CUSTOM_LEVEL        0x0002
-#define PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL    0x0004
-#define PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS  0x0008
-#define PNG_FLAG_ZLIB_CUSTOM_METHOD       0x0010
-#define PNG_FLAG_ZLIB_FINISHED            0x0020
+#define PNG_FLAG_ZSTREAM_INITIALIZED      0x0002 /* Added to libpng-1.6.0 */
+                                  /*      0x0004    unused */
+#define PNG_FLAG_ZSTREAM_ENDED            0x0008 /* Added to libpng-1.6.0 */
+                                  /*      0x0010    unused */
+                                  /*      0x0020    unused */
 #define PNG_FLAG_ROW_INIT                 0x0040
 #define PNG_FLAG_FILLER_AFTER             0x0080
 #define PNG_FLAG_CRC_ANCILLARY_USE        0x0100
 #define PNG_FLAG_CRC_ANCILLARY_NOWARN     0x0200
 #define PNG_FLAG_CRC_CRITICAL_USE         0x0400
 #define PNG_FLAG_CRC_CRITICAL_IGNORE      0x0800
-#define PNG_FLAG_ASSUME_sRGB              0x1000  /* Added to libpng-1.5.4 */
-#define PNG_FLAG_OPTIMIZE_ALPHA           0x2000  /* Added to libpng-1.5.4 */
-#define PNG_FLAG_DETECT_UNINITIALIZED     0x4000  /* Added to libpng-1.5.4 */
-#define PNG_FLAG_KEEP_UNKNOWN_CHUNKS      0x8000
-#define PNG_FLAG_KEEP_UNSAFE_CHUNKS       0x10000
-#define PNG_FLAG_LIBRARY_MISMATCH         0x20000
-#define PNG_FLAG_STRIP_ERROR_NUMBERS      0x40000
-#define PNG_FLAG_STRIP_ERROR_TEXT         0x80000
-#define PNG_FLAG_MALLOC_NULL_MEM_OK       0x100000
-                                  /*      0x200000  unused */
-                                  /*      0x400000  unused */
-#define PNG_FLAG_BENIGN_ERRORS_WARN       0x800000  /* Added to libpng-1.4.0 */
-#define PNG_FLAG_ZTXT_CUSTOM_STRATEGY    0x1000000  /* 5 lines added */
-#define PNG_FLAG_ZTXT_CUSTOM_LEVEL       0x2000000  /* to libpng-1.5.4 */
-#define PNG_FLAG_ZTXT_CUSTOM_MEM_LEVEL   0x4000000
-#define PNG_FLAG_ZTXT_CUSTOM_WINDOW_BITS 0x8000000
-#define PNG_FLAG_ZTXT_CUSTOM_METHOD      0x10000000
-                                  /*     0x20000000  unused */
-                                  /*     0x40000000  unused */
+#define PNG_FLAG_ASSUME_sRGB              0x1000 /* Added to libpng-1.5.4 */
+#define PNG_FLAG_OPTIMIZE_ALPHA           0x2000 /* Added to libpng-1.5.4 */
+#define PNG_FLAG_DETECT_UNINITIALIZED     0x4000 /* Added to libpng-1.5.4 */
+/* #define PNG_FLAG_KEEP_UNKNOWN_CHUNKS      0x8000 */
+/* #define PNG_FLAG_KEEP_UNSAFE_CHUNKS      0x10000 */
+#define PNG_FLAG_LIBRARY_MISMATCH        0x20000
+#define PNG_FLAG_STRIP_ERROR_NUMBERS     0x40000
+#define PNG_FLAG_STRIP_ERROR_TEXT        0x80000
+#define PNG_FLAG_BENIGN_ERRORS_WARN     0x100000 /* Added to libpng-1.4.0 */
+#define PNG_FLAG_APP_WARNINGS_WARN      0x200000 /* Added to libpng-1.6.0 */
+#define PNG_FLAG_APP_ERRORS_WARN        0x400000 /* Added to libpng-1.6.0 */
+                                  /*    0x800000    unused */
+                                  /*   0x1000000    unused */
+                                  /*   0x2000000    unused */
+                                  /*   0x4000000    unused */
+                                  /*   0x8000000    unused */
+                                  /*  0x10000000    unused */
+                                  /*  0x20000000    unused */
+                                  /*  0x40000000    unused */
 
 #define PNG_FLAG_CRC_ANCILLARY_MASK (PNG_FLAG_CRC_ANCILLARY_USE | \
                                      PNG_FLAG_CRC_ANCILLARY_NOWARN)
@@ -564,24 +613,23 @@ typedef PNG_CONST png_uint_16p FAR * png_const_uint_16pp;
 #define PNG_FLAG_CRC_MASK           (PNG_FLAG_CRC_ANCILLARY_MASK | \
                                      PNG_FLAG_CRC_CRITICAL_MASK)
 
-/* zlib.h declares a magic type 'uInt' that limits the amount of data that zlib
- * can handle at once.  This type need be no larger than 16 bits (so maximum of
- * 65535), this define allows us to discover how big it is, but limited by the
- * maximuum for png_size_t.  The value can be overriden in a library build
- * (pngusr.h, or set it in CPPFLAGS) and it works to set it to a considerably
- * lower value (e.g. 255 works).  A lower value may help memory usage (slightly)
- * and may even improve performance on some systems (and degrade it on others.)
- */
-#ifndef ZLIB_IO_MAX
-#  define ZLIB_IO_MAX ((uInt)-1)
-#endif
-
 /* Save typing and make code easier to understand */
 
 #define PNG_COLOR_DIST(c1, c2) (abs((int)((c1).red) - (int)((c2).red)) + \
    abs((int)((c1).green) - (int)((c2).green)) + \
    abs((int)((c1).blue) - (int)((c2).blue)))
 
+/* Added to libpng-1.6.0: scale a 16-bit value in the range 0..65535 to 0..255
+ * by dividing by 257 *with rounding*.  This macro is exact for the given range.
+ * See the discourse in pngrtran.c png_do_scale_16_to_8.  The values in the
+ * macro were established by experiment (modifying the added value).  The macro
+ * has a second variant that takes a value already scaled by 255 and divides by
+ * 65535 - this has a maximum error of .502.  Over the range 0..65535*65535 it
+ * only gives off-by-one errors and only for 0.5% (1 in 200) of the values.
+ */
+#define PNG_DIV65535(v24) (((v24) + 32895) >> 16)
+#define PNG_DIV257(v16) PNG_DIV65535((png_uint_32)(v16) * 255)
+
 /* Added to libpng-1.2.6 JB */
 #define PNG_ROWBYTES(pixel_bits, width) \
     ((pixel_bits) >= 8 ? \
@@ -629,10 +677,10 @@ typedef PNG_CONST png_uint_16p FAR * png_const_uint_16pp;
 #ifdef PNG_FIXED_POINT_MACRO_SUPPORTED
 #define png_fixed(png_ptr, fp, s) ((fp) <= 21474 && (fp) >= -21474 ?\
     ((png_fixed_point)(100000 * (fp))) : (png_fixed_error(png_ptr, s),0))
-#else
-PNG_EXTERN png_fixed_point png_fixed PNGARG((png_structp png_ptr, double fp,
-   png_const_charp text));
 #endif
+/* else the corresponding function is defined below, inside the scope of the
+ * cplusplus test.
+ */
 #endif
 
 /* Constants for known chunk types.  If you need to add a chunk, define the name
@@ -649,53 +697,82 @@ PNG_EXTERN png_fixed_point png_fixed PNGARG((png_structp png_ptr, double fp,
  * architectures where (int) is only 16 bits.
  */
 #define PNG_32b(b,s) ((png_uint_32)(b) << (s))
-#define PNG_CHUNK(b1,b2,b3,b4) \
+#define PNG_U32(b1,b2,b3,b4) \
    (PNG_32b(b1,24) | PNG_32b(b2,16) | PNG_32b(b3,8) | PNG_32b(b4,0))
 
-#define png_IHDR PNG_CHUNK( 73,  72,  68,  82)
-#define png_IDAT PNG_CHUNK( 73,  68,  65,  84)
-#define png_IEND PNG_CHUNK( 73,  69,  78,  68)
-#define png_PLTE PNG_CHUNK( 80,  76,  84,  69)
-#define png_bKGD PNG_CHUNK( 98,  75,  71,  68)
-#define png_cHRM PNG_CHUNK( 99,  72,  82,  77)
-#define png_gAMA PNG_CHUNK(103,  65,  77,  65)
-#define png_hIST PNG_CHUNK(104,  73,  83,  84)
-#define png_iCCP PNG_CHUNK(105,  67,  67,  80)
-#define png_iTXt PNG_CHUNK(105,  84,  88, 116)
-#define png_oFFs PNG_CHUNK(111,  70,  70, 115)
-#define png_pCAL PNG_CHUNK(112,  67,  65,  76)
-#define png_sCAL PNG_CHUNK(115,  67,  65,  76)
-#define png_pHYs PNG_CHUNK(112,  72,  89, 115)
-#define png_sBIT PNG_CHUNK(115,  66,  73,  84)
-#define png_sPLT PNG_CHUNK(115,  80,  76,  84)
-#define png_sRGB PNG_CHUNK(115,  82,  71,  66)
-#define png_sTER PNG_CHUNK(115,  84,  69,  82)
-#define png_tEXt PNG_CHUNK(116,  69,  88, 116)
-#define png_tIME PNG_CHUNK(116,  73,  77,  69)
-#define png_tRNS PNG_CHUNK(116,  82,  78,  83)
-#define png_zTXt PNG_CHUNK(122,  84,  88, 116)
+/* Constants for known chunk types.
+ *
+ * MAINTAINERS: If you need to add a chunk, define the name here.
+ * For historical reasons these constants have the form png_<name>; i.e.
+ * the prefix is lower case.  Please use decimal values as the parameters to
+ * match the ISO PNG specification and to avoid relying on the C locale
+ * interpretation of character values.  Please keep the list sorted.
+ *
+ * Notice that PNG_U32 is used to define a 32-bit value for the 4 byte chunk
+ * type.  In fact the specification does not express chunk types this way,
+ * however using a 32-bit value means that the chunk type can be read from the
+ * stream using exactly the same code as used for a 32-bit unsigned value and
+ * can be examined far more efficiently (using one arithmetic compare).
+ *
+ * Prior to 1.5.6 the chunk type constants were expressed as C strings.  The
+ * libpng API still uses strings for 'unknown' chunks and a macro,
+ * PNG_STRING_FROM_CHUNK, allows a string to be generated if required.  Notice
+ * that for portable code numeric values must still be used; the string "IHDR"
+ * is not portable and neither is PNG_U32('I', 'H', 'D', 'R').
+ *
+ * In 1.7.0 the definitions will be made public in png.h to avoid having to
+ * duplicate the same definitions in application code.
+ */
+#define png_IDAT PNG_U32( 73,  68,  65,  84)
+#define png_IEND PNG_U32( 73,  69,  78,  68)
+#define png_IHDR PNG_U32( 73,  72,  68,  82)
+#define png_PLTE PNG_U32( 80,  76,  84,  69)
+#define png_bKGD PNG_U32( 98,  75,  71,  68)
+#define png_cHRM PNG_U32( 99,  72,  82,  77)
+#define png_fRAc PNG_U32(102,  82,  65,  99) /* registered, not defined */
+#define png_gAMA PNG_U32(103,  65,  77,  65)
+#define png_gIFg PNG_U32(103,  73,  70, 103)
+#define png_gIFt PNG_U32(103,  73,  70, 116) /* deprecated */
+#define png_gIFx PNG_U32(103,  73,  70, 120)
+#define png_hIST PNG_U32(104,  73,  83,  84)
+#define png_iCCP PNG_U32(105,  67,  67,  80)
+#define png_iTXt PNG_U32(105,  84,  88, 116)
+#define png_oFFs PNG_U32(111,  70,  70, 115)
+#define png_pCAL PNG_U32(112,  67,  65,  76)
+#define png_pHYs PNG_U32(112,  72,  89, 115)
+#define png_sBIT PNG_U32(115,  66,  73,  84)
+#define png_sCAL PNG_U32(115,  67,  65,  76)
+#define png_sPLT PNG_U32(115,  80,  76,  84)
+#define png_sRGB PNG_U32(115,  82,  71,  66)
+#define png_sTER PNG_U32(115,  84,  69,  82)
+#define png_tEXt PNG_U32(116,  69,  88, 116)
+#define png_tIME PNG_U32(116,  73,  77,  69)
+#define png_tRNS PNG_U32(116,  82,  78,  83)
+#define png_zTXt PNG_U32(122,  84,  88, 116)
 
 /* The following will work on (signed char*) strings, whereas the get_uint_32
  * macro will fail on top-bit-set values because of the sign extension.
  */
 #define PNG_CHUNK_FROM_STRING(s)\
-   PNG_CHUNK(0xff&(s)[0], 0xff&(s)[1], 0xff&(s)[2], 0xff&(s)[3])
+   PNG_U32(0xff & (s)[0], 0xff & (s)[1], 0xff & (s)[2], 0xff & (s)[3])
 
 /* This uses (char), not (png_byte) to avoid warnings on systems where (char) is
  * signed and the argument is a (char[])  This macro will fail miserably on
  * systems where (char) is more than 8 bits.
  */
 #define PNG_STRING_FROM_CHUNK(s,c)\
-   (void)(((char*)(s))[0]=(char)((c)>>24), ((char*)(s))[1]=(char)((c)>>16),\
-   ((char*)(s))[2]=(char)((c)>>8), ((char*)(s))[3]=(char)((c)))
+   (void)(((char*)(s))[0]=(char)(((c)>>24) & 0xff), \
+   ((char*)(s))[1]=(char)(((c)>>16) & 0xff),\
+   ((char*)(s))[2]=(char)(((c)>>8) & 0xff), \
+   ((char*)(s))[3]=(char)((c & 0xff)))
 
 /* Do the same but terminate with a null character. */
 #define PNG_CSTRING_FROM_CHUNK(s,c)\
    (void)(PNG_STRING_FROM_CHUNK(s,c), ((char*)(s))[4] = 0)
 
 /* Test on flag values as defined in the spec (section 5.4): */
-#define PNG_CHUNK_ANCILLIARY(c)   (1 & ((c) >> 29))
-#define PNG_CHUNK_CRITICAL(c)     (!PNG_CHUNK_ANCILLIARY(c))
+#define PNG_CHUNK_ANCILLARY(c)   (1 & ((c) >> 29))
+#define PNG_CHUNK_CRITICAL(c)     (!PNG_CHUNK_ANCILLARY(c))
 #define PNG_CHUNK_PRIVATE(c)      (1 & ((c) >> 21))
 #define PNG_CHUNK_RESERVED(c)     (1 & ((c) >> 13))
 #define PNG_CHUNK_SAFE_TO_COPY(c) (1 & ((c) >>  5))
@@ -705,113 +782,212 @@ PNG_EXTERN png_fixed_point png_fixed PNGARG((png_structp png_ptr, double fp,
 #define PNG_GAMMA_MAC_INVERSE 65909
 #define PNG_GAMMA_sRGB_INVERSE 45455
 
+/* Almost everything below is C specific; the #defines above can be used in
+ * non-C code (so long as it is C-preprocessed) the rest of this stuff cannot.
+ */
+#ifndef PNG_VERSION_INFO_ONLY
+
+#include "pngstruct.h"
+#include "pnginfo.h"
+
+/* Validate the include paths - the include path used to generate pnglibconf.h
+ * must match that used in the build, or we must be using pnglibconf.h.prebuilt:
+ */
+#if PNG_ZLIB_VERNUM != 0 && PNG_ZLIB_VERNUM != ZLIB_VERNUM
+#  error ZLIB_VERNUM != PNG_ZLIB_VERNUM \
+      "-I (include path) error: see the notes in pngpriv.h"
+   /* This means that when pnglibconf.h was built the copy of zlib.h that it
+    * used is not the same as the one being used here.  Because the build of
+    * libpng makes decisions to use inflateInit2 and inflateReset2 based on the
+    * zlib version number and because this affects handling of certain broken
+    * PNG files the -I directives must match.
+    *
+    * The most likely explanation is that you passed a -I in CFLAGS. This will
+    * not work; all the preprocessor directories and in particular all the -I
+    * directives must be in CPPFLAGS.
+    */
+#endif
+
+/* This is used for 16 bit gamma tables -- only the top level pointers are
+ * const; this could be changed:
+ */
+typedef const png_uint_16p * png_const_uint_16pp;
+
+/* Added to libpng-1.5.7: sRGB conversion tables */
+#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
+   defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
+#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
+PNG_INTERNAL_DATA(const png_uint_16, png_sRGB_table, [256]);
+   /* Convert from an sRGB encoded value 0..255 to a 16-bit linear value,
+    * 0..65535.  This table gives the closest 16-bit answers (no errors).
+    */
+#endif
+
+PNG_INTERNAL_DATA(const png_uint_16, png_sRGB_base, [512]);
+PNG_INTERNAL_DATA(const png_byte, png_sRGB_delta, [512]);
+
+#define PNG_sRGB_FROM_LINEAR(linear) \
+  ((png_byte)(0xff & ((png_sRGB_base[(linear)>>15] \
+   + ((((linear) & 0x7fff)*png_sRGB_delta[(linear)>>15])>>12)) >> 8)))
+   /* Given a value 'linear' in the range 0..255*65535 calculate the 8-bit sRGB
+    * encoded value with maximum error 0.646365.  Note that the input is not a
+    * 16-bit value; it has been multiplied by 255! */
+#endif /* SIMPLIFIED_READ/WRITE */
+
 
 /* Inhibit C++ name-mangling for libpng functions but not for system calls. */
 #ifdef __cplusplus
 extern "C" {
 #endif /* __cplusplus */
 
-/* These functions are used internally in the code.  They generally
- * shouldn't be used unless you are writing code to add or replace some
- * functionality in libpng.  More information about most functions can
- * be found in the files where the functions are located.
+/* Internal functions; these are not exported from a DLL however because they
+ * are used within several of the C source files they have to be C extern.
+ *
+ * All of these functions must be declared with PNG_INTERNAL_FUNCTION.
  */
 
+/* Zlib support */
+#define PNG_UNEXPECTED_ZLIB_RETURN (-7)
+PNG_INTERNAL_FUNCTION(void, png_zstream_error,(png_structrp png_ptr, int ret),
+   PNG_EMPTY);
+   /* Used by the zlib handling functions to ensure that z_stream::msg is always
+    * set before they return.
+    */
+
+#ifdef PNG_WRITE_SUPPORTED
+PNG_INTERNAL_FUNCTION(void,png_free_buffer_list,(png_structrp png_ptr,
+   png_compression_bufferp *list),PNG_EMPTY);
+   /* Free the buffer list used by the compressed write code. */
+#endif
+
+#if defined(PNG_FLOATING_POINT_SUPPORTED) && \
+   !defined(PNG_FIXED_POINT_MACRO_SUPPORTED) && \
+   (defined(PNG_gAMA_SUPPORTED) || defined(PNG_cHRM_SUPPORTED) || \
+   defined(PNG_sCAL_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) || \
+   defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)) || \
+   (defined(PNG_sCAL_SUPPORTED) && \
+   defined(PNG_FLOATING_ARITHMETIC_SUPPORTED))
+PNG_INTERNAL_FUNCTION(png_fixed_point,png_fixed,(png_const_structrp png_ptr,
+   double fp, png_const_charp text),PNG_EMPTY);
+#endif
+
 /* Check the user version string for compatibility, returns false if the version
  * numbers aren't compatible.
  */
-PNG_EXTERN int png_user_version_check(png_structp png_ptr,
-   png_const_charp user_png_ver);
+PNG_INTERNAL_FUNCTION(int,png_user_version_check,(png_structrp png_ptr,
+   png_const_charp user_png_ver),PNG_EMPTY);
 
-/* Allocate memory for an internal libpng struct */
-PNG_EXTERN PNG_FUNCTION(png_voidp,png_create_struct,PNGARG((int type)),
-   PNG_ALLOCATED);
+/* Internal base allocator - no messages, NULL on failure to allocate.  This
+ * does, however, call the application provided allocator and that could call
+ * png_error (although that would be a bug in the application implementation.)
+ */
+PNG_INTERNAL_FUNCTION(png_voidp,png_malloc_base,(png_const_structrp png_ptr,
+   png_alloc_size_t size),PNG_ALLOCATED);
 
-/* Free memory from internal libpng struct */
-PNG_EXTERN void png_destroy_struct PNGARG((png_voidp struct_ptr));
+#if defined(PNG_TEXT_SUPPORTED) || defined(PNG_sPLT_SUPPORTED) ||\
+   defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED)
+/* Internal array allocator, outputs no error or warning messages on failure,
+ * just returns NULL.
+ */
+PNG_INTERNAL_FUNCTION(png_voidp,png_malloc_array,(png_const_structrp png_ptr,
+   int nelements, size_t element_size),PNG_ALLOCATED);
 
-PNG_EXTERN PNG_FUNCTION(png_voidp,png_create_struct_2,
-   PNGARG((int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr)),
-   PNG_ALLOCATED);
-PNG_EXTERN void png_destroy_struct_2 PNGARG((png_voidp struct_ptr,
-    png_free_ptr free_fn, png_voidp mem_ptr));
+/* The same but an existing array is extended by add_elements.  This function
+ * also memsets the new elements to 0 and copies the old elements.  The old
+ * array is not freed or altered.
+ */
+PNG_INTERNAL_FUNCTION(png_voidp,png_realloc_array,(png_const_structrp png_ptr,
+   png_const_voidp array, int old_elements, int add_elements,
+   size_t element_size),PNG_ALLOCATED);
+#endif /* text, sPLT or unknown chunks */
+
+/* Magic to create a struct when there is no struct to call the user supplied
+ * memory allocators.  Because error handling has not been set up the memory
+ * handlers can't safely call png_error, but this is an obscure and undocumented
+ * restriction so libpng has to assume that the 'free' handler, at least, might
+ * call png_error.
+ */
+PNG_INTERNAL_FUNCTION(png_structp,png_create_png_struct,
+   (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
+    png_error_ptr warn_fn, png_voidp mem_ptr, png_malloc_ptr malloc_fn,
+    png_free_ptr free_fn),PNG_ALLOCATED);
 
-/* Free any memory that info_ptr points to and reset struct. */
-PNG_EXTERN void png_info_destroy PNGARG((png_structp png_ptr,
-    png_infop info_ptr));
+/* Free memory from internal libpng struct */
+PNG_INTERNAL_FUNCTION(void,png_destroy_png_struct,(png_structrp png_ptr),
+   PNG_EMPTY);
+
+/* Free an allocated jmp_buf (always succeeds) */
+PNG_INTERNAL_FUNCTION(void,png_free_jmpbuf,(png_structrp png_ptr),PNG_EMPTY);
 
 /* Function to allocate memory for zlib.  PNGAPI is disallowed. */
-PNG_EXTERN PNG_FUNCTION(voidpf,png_zalloc,PNGARG((voidpf png_ptr, uInt items,
-   uInt size)),PNG_ALLOCATED);
+PNG_INTERNAL_FUNCTION(voidpf,png_zalloc,(voidpf png_ptr, uInt items, uInt size),
+   PNG_ALLOCATED);
 
 /* Function to free memory for zlib.  PNGAPI is disallowed. */
-PNG_EXTERN void png_zfree PNGARG((voidpf png_ptr, voidpf ptr));
+PNG_INTERNAL_FUNCTION(void,png_zfree,(voidpf png_ptr, voidpf ptr),PNG_EMPTY);
 
 /* Next four functions are used internally as callbacks.  PNGCBAPI is required
  * but not PNG_EXPORT.  PNGAPI added at libpng version 1.2.3, changed to
  * PNGCBAPI at 1.5.0
  */
 
-PNG_EXTERN void PNGCBAPI png_default_read_data PNGARG((png_structp png_ptr,
-    png_bytep data, png_size_t length));
+PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_default_read_data,(png_structp png_ptr,
+    png_bytep data, png_size_t length),PNG_EMPTY);
 
 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
-PNG_EXTERN void PNGCBAPI png_push_fill_buffer PNGARG((png_structp png_ptr,
-    png_bytep buffer, png_size_t length));
+PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_push_fill_buffer,(png_structp png_ptr,
+    png_bytep buffer, png_size_t length),PNG_EMPTY);
 #endif
 
-PNG_EXTERN void PNGCBAPI png_default_write_data PNGARG((png_structp png_ptr,
-    png_bytep data, png_size_t length));
+PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_default_write_data,(png_structp png_ptr,
+    png_bytep data, png_size_t length),PNG_EMPTY);
 
 #ifdef PNG_WRITE_FLUSH_SUPPORTED
 #  ifdef PNG_STDIO_SUPPORTED
-PNG_EXTERN void PNGCBAPI png_default_flush PNGARG((png_structp png_ptr));
+PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_default_flush,(png_structp png_ptr),
+   PNG_EMPTY);
 #  endif
 #endif
 
 /* Reset the CRC variable */
-PNG_EXTERN void png_reset_crc PNGARG((png_structp png_ptr));
+PNG_INTERNAL_FUNCTION(void,png_reset_crc,(png_structrp png_ptr),PNG_EMPTY);
 
 /* Write the "data" buffer to whatever output you are using */
-PNG_EXTERN void png_write_data PNGARG((png_structp png_ptr,
-    png_const_bytep data, png_size_t length));
+PNG_INTERNAL_FUNCTION(void,png_write_data,(png_structrp png_ptr,
+    png_const_bytep data, png_size_t length),PNG_EMPTY);
 
 /* Read and check the PNG file signature */
-PNG_EXTERN void png_read_sig PNGARG((png_structp png_ptr, png_infop info_ptr));
+PNG_INTERNAL_FUNCTION(void,png_read_sig,(png_structrp png_ptr,
+   png_inforp info_ptr),PNG_EMPTY);
 
 /* Read the chunk header (length + type name) */
-PNG_EXTERN png_uint_32 png_read_chunk_header PNGARG((png_structp png_ptr));
+PNG_INTERNAL_FUNCTION(png_uint_32,png_read_chunk_header,(png_structrp png_ptr),
+   PNG_EMPTY);
 
 /* Read data from whatever input you are using into the "data" buffer */
-PNG_EXTERN void png_read_data PNGARG((png_structp png_ptr, png_bytep data,
-    png_size_t length));
+PNG_INTERNAL_FUNCTION(void,png_read_data,(png_structrp png_ptr, png_bytep data,
+    png_size_t length),PNG_EMPTY);
 
 /* Read bytes into buf, and update png_ptr->crc */
-PNG_EXTERN void png_crc_read PNGARG((png_structp png_ptr, png_bytep buf,
-    png_size_t length));
-
-/* Decompress data in a chunk that uses compression */
-#if defined(PNG_READ_COMPRESSED_TEXT_SUPPORTED)
-PNG_EXTERN void png_decompress_chunk PNGARG((png_structp png_ptr,
-    int comp_type, png_size_t chunklength, png_size_t prefix_length,
-    png_size_t *data_length));
-#endif
+PNG_INTERNAL_FUNCTION(void,png_crc_read,(png_structrp png_ptr, png_bytep buf,
+    png_uint_32 length),PNG_EMPTY);
 
 /* Read "skip" bytes, read the file crc, and (optionally) verify png_ptr->crc */
-PNG_EXTERN int png_crc_finish PNGARG((png_structp png_ptr, png_uint_32 skip));
+PNG_INTERNAL_FUNCTION(int,png_crc_finish,(png_structrp png_ptr,
+   png_uint_32 skip),PNG_EMPTY);
 
 /* Read the CRC from the file and compare it to the libpng calculated CRC */
-PNG_EXTERN int png_crc_error PNGARG((png_structp png_ptr));
+PNG_INTERNAL_FUNCTION(int,png_crc_error,(png_structrp png_ptr),PNG_EMPTY);
 
 /* Calculate the CRC over a section of data.  Note that we are only
  * passing a maximum of 64K on systems that have this as a memory limit,
  * since this is the maximum buffer size we can specify.
  */
-PNG_EXTERN void png_calculate_crc PNGARG((png_structp png_ptr,
-    png_const_bytep ptr, png_size_t length));
+PNG_INTERNAL_FUNCTION(void,png_calculate_crc,(png_structrp png_ptr,
+   png_const_bytep ptr, png_size_t length),PNG_EMPTY);
 
 #ifdef PNG_WRITE_FLUSH_SUPPORTED
-PNG_EXTERN void png_flush PNGARG((png_structp png_ptr));
+PNG_INTERNAL_FUNCTION(void,png_flush,(png_structrp png_ptr),PNG_EMPTY);
 #endif
 
 /* Write various chunks */
@@ -819,145 +995,130 @@ PNG_EXTERN void png_flush PNGARG((png_structp png_ptr));
 /* Write the IHDR chunk, and update the png_struct with the necessary
  * information.
  */
-PNG_EXTERN void png_write_IHDR PNGARG((png_structp png_ptr, png_uint_32 width,
-    png_uint_32 height,
-    int bit_depth, int color_type, int compression_method, int filter_method,
-    int interlace_method));
+PNG_INTERNAL_FUNCTION(void,png_write_IHDR,(png_structrp png_ptr,
+   png_uint_32 width, png_uint_32 height, int bit_depth, int color_type,
+   int compression_method, int filter_method, int interlace_method),PNG_EMPTY);
 
-PNG_EXTERN void png_write_PLTE PNGARG((png_structp png_ptr,
-    png_const_colorp palette, png_uint_32 num_pal));
+PNG_INTERNAL_FUNCTION(void,png_write_PLTE,(png_structrp png_ptr,
+   png_const_colorp palette, png_uint_32 num_pal),PNG_EMPTY);
 
-PNG_EXTERN void png_write_IDAT PNGARG((png_structp png_ptr, png_bytep data,
-    png_size_t length));
+PNG_INTERNAL_FUNCTION(void,png_compress_IDAT,(png_structrp png_ptr,
+   png_const_bytep row_data, png_alloc_size_t row_data_length, int flush),
+   PNG_EMPTY);
 
-PNG_EXTERN void png_write_IEND PNGARG((png_structp png_ptr));
+PNG_INTERNAL_FUNCTION(void,png_write_IEND,(png_structrp png_ptr),PNG_EMPTY);
 
 #ifdef PNG_WRITE_gAMA_SUPPORTED
-#  ifdef PNG_FLOATING_POINT_SUPPORTED
-PNG_EXTERN void png_write_gAMA PNGARG((png_structp png_ptr, double file_gamma));
-#  endif
-#  ifdef PNG_FIXED_POINT_SUPPORTED
-PNG_EXTERN void png_write_gAMA_fixed PNGARG((png_structp png_ptr,
-    png_fixed_point file_gamma));
-#  endif
+PNG_INTERNAL_FUNCTION(void,png_write_gAMA_fixed,(png_structrp png_ptr,
+    png_fixed_point file_gamma),PNG_EMPTY);
 #endif
 
 #ifdef PNG_WRITE_sBIT_SUPPORTED
-PNG_EXTERN void png_write_sBIT PNGARG((png_structp png_ptr,
-    png_const_color_8p sbit, int color_type));
+PNG_INTERNAL_FUNCTION(void,png_write_sBIT,(png_structrp png_ptr,
+    png_const_color_8p sbit, int color_type),PNG_EMPTY);
 #endif
 
 #ifdef PNG_WRITE_cHRM_SUPPORTED
-#  ifdef PNG_FLOATING_POINT_SUPPORTED
-PNG_EXTERN void png_write_cHRM PNGARG((png_structp png_ptr,
-    double white_x, double white_y,
-    double red_x, double red_y, double green_x, double green_y,
-    double blue_x, double blue_y));
-#  endif
-PNG_EXTERN void png_write_cHRM_fixed PNGARG((png_structp png_ptr,
-    png_fixed_point int_white_x, png_fixed_point int_white_y,
-    png_fixed_point int_red_x, png_fixed_point int_red_y, png_fixed_point
-    int_green_x, png_fixed_point int_green_y, png_fixed_point int_blue_x,
-    png_fixed_point int_blue_y));
+PNG_INTERNAL_FUNCTION(void,png_write_cHRM_fixed,(png_structrp png_ptr,
+    const png_xy *xy), PNG_EMPTY);
+    /* The xy value must have been previously validated */
 #endif
 
 #ifdef PNG_WRITE_sRGB_SUPPORTED
-PNG_EXTERN void png_write_sRGB PNGARG((png_structp png_ptr,
-    int intent));
+PNG_INTERNAL_FUNCTION(void,png_write_sRGB,(png_structrp png_ptr,
+    int intent),PNG_EMPTY);
 #endif
 
 #ifdef PNG_WRITE_iCCP_SUPPORTED
-PNG_EXTERN void png_write_iCCP PNGARG((png_structp png_ptr,
-    png_const_charp name, int compression_type,
-    png_const_charp profile, int proflen));
-   /* Note to maintainer: profile should be png_bytep */
+PNG_INTERNAL_FUNCTION(void,png_write_iCCP,(png_structrp png_ptr,
+   png_const_charp name, png_const_bytep profile), PNG_EMPTY);
+   /* The profile must have been previously validated for correctness, the
+    * length comes from the first four bytes.  Only the base, deflate,
+    * compression is supported.
+    */
 #endif
 
 #ifdef PNG_WRITE_sPLT_SUPPORTED
-PNG_EXTERN void png_write_sPLT PNGARG((png_structp png_ptr,
-    png_const_sPLT_tp palette));
+PNG_INTERNAL_FUNCTION(void,png_write_sPLT,(png_structrp png_ptr,
+    png_const_sPLT_tp palette),PNG_EMPTY);
 #endif
 
 #ifdef PNG_WRITE_tRNS_SUPPORTED
-PNG_EXTERN void png_write_tRNS PNGARG((png_structp png_ptr,
+PNG_INTERNAL_FUNCTION(void,png_write_tRNS,(png_structrp png_ptr,
     png_const_bytep trans, png_const_color_16p values, int number,
-    int color_type));
+    int color_type),PNG_EMPTY);
 #endif
 
 #ifdef PNG_WRITE_bKGD_SUPPORTED
-PNG_EXTERN void png_write_bKGD PNGARG((png_structp png_ptr,
-    png_const_color_16p values, int color_type));
+PNG_INTERNAL_FUNCTION(void,png_write_bKGD,(png_structrp png_ptr,
+    png_const_color_16p values, int color_type),PNG_EMPTY);
 #endif
 
 #ifdef PNG_WRITE_hIST_SUPPORTED
-PNG_EXTERN void png_write_hIST PNGARG((png_structp png_ptr,
-    png_const_uint_16p hist, int num_hist));
+PNG_INTERNAL_FUNCTION(void,png_write_hIST,(png_structrp png_ptr,
+    png_const_uint_16p hist, int num_hist),PNG_EMPTY);
 #endif
 
 /* Chunks that have keywords */
-#if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_pCAL_SUPPORTED) || \
-    defined(PNG_WRITE_iCCP_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
-PNG_EXTERN png_size_t png_check_keyword PNGARG((png_structp png_ptr,
-    png_const_charp key, png_charpp new_key));
-#endif
-
 #ifdef PNG_WRITE_tEXt_SUPPORTED
-PNG_EXTERN void png_write_tEXt PNGARG((png_structp png_ptr, png_const_charp key,
-    png_const_charp text, png_size_t text_len));
+PNG_INTERNAL_FUNCTION(void,png_write_tEXt,(png_structrp png_ptr,
+   png_const_charp key, png_const_charp text, png_size_t text_len),PNG_EMPTY);
 #endif
 
 #ifdef PNG_WRITE_zTXt_SUPPORTED
-PNG_EXTERN void png_write_zTXt PNGARG((png_structp png_ptr, png_const_charp key,
-    png_const_charp text, png_size_t text_len, int compression));
+PNG_INTERNAL_FUNCTION(void,png_write_zTXt,(png_structrp png_ptr, png_const_charp
+    key, png_const_charp text, int compression),PNG_EMPTY);
 #endif
 
 #ifdef PNG_WRITE_iTXt_SUPPORTED
-PNG_EXTERN void png_write_iTXt PNGARG((png_structp png_ptr,
+PNG_INTERNAL_FUNCTION(void,png_write_iTXt,(png_structrp png_ptr,
     int compression, png_const_charp key, png_const_charp lang,
-    png_const_charp lang_key, png_const_charp text));
+    png_const_charp lang_key, png_const_charp text),PNG_EMPTY);
 #endif
 
 #ifdef PNG_TEXT_SUPPORTED  /* Added at version 1.0.14 and 1.2.4 */
-PNG_EXTERN int png_set_text_2 PNGARG((png_structp png_ptr,
-    png_infop info_ptr, png_const_textp text_ptr, int num_text));
+PNG_INTERNAL_FUNCTION(int,png_set_text_2,(png_const_structrp png_ptr,
+    png_inforp info_ptr, png_const_textp text_ptr, int num_text),PNG_EMPTY);
 #endif
 
 #ifdef PNG_WRITE_oFFs_SUPPORTED
-PNG_EXTERN void png_write_oFFs PNGARG((png_structp png_ptr,
-    png_int_32 x_offset, png_int_32 y_offset, int unit_type));
+PNG_INTERNAL_FUNCTION(void,png_write_oFFs,(png_structrp png_ptr,
+    png_int_32 x_offset, png_int_32 y_offset, int unit_type),PNG_EMPTY);
 #endif
 
 #ifdef PNG_WRITE_pCAL_SUPPORTED
-PNG_EXTERN void png_write_pCAL PNGARG((png_structp png_ptr, png_charp purpose,
-    png_int_32 X0, png_int_32 X1, int type, int nparams,
-    png_const_charp units, png_charpp params));
+PNG_INTERNAL_FUNCTION(void,png_write_pCAL,(png_structrp png_ptr,
+    png_charp purpose, png_int_32 X0, png_int_32 X1, int type, int nparams,
+    png_const_charp units, png_charpp params),PNG_EMPTY);
 #endif
 
 #ifdef PNG_WRITE_pHYs_SUPPORTED
-PNG_EXTERN void png_write_pHYs PNGARG((png_structp png_ptr,
+PNG_INTERNAL_FUNCTION(void,png_write_pHYs,(png_structrp png_ptr,
     png_uint_32 x_pixels_per_unit, png_uint_32 y_pixels_per_unit,
-    int unit_type));
+    int unit_type),PNG_EMPTY);
 #endif
 
 #ifdef PNG_WRITE_tIME_SUPPORTED
-PNG_EXTERN void png_write_tIME PNGARG((png_structp png_ptr,
-    png_const_timep mod_time));
+PNG_INTERNAL_FUNCTION(void,png_write_tIME,(png_structrp png_ptr,
+    png_const_timep mod_time),PNG_EMPTY);
 #endif
 
 #ifdef PNG_WRITE_sCAL_SUPPORTED
-PNG_EXTERN void png_write_sCAL_s PNGARG((png_structp png_ptr,
-    int unit, png_const_charp width, png_const_charp height));
+PNG_INTERNAL_FUNCTION(void,png_write_sCAL_s,(png_structrp png_ptr,
+    int unit, png_const_charp width, png_const_charp height),PNG_EMPTY);
 #endif
 
 /* Called when finished processing a row of data */
-PNG_EXTERN void png_write_finish_row PNGARG((png_structp png_ptr));
+PNG_INTERNAL_FUNCTION(void,png_write_finish_row,(png_structrp png_ptr),
+    PNG_EMPTY);
 
 /* Internal use only.   Called before first row of data */
-PNG_EXTERN void png_write_start_row PNGARG((png_structp png_ptr));
+PNG_INTERNAL_FUNCTION(void,png_write_start_row,(png_structrp png_ptr),
+    PNG_EMPTY);
 
 /* Combine a row of data, dealing with alpha, etc. if requested.  'row' is an
  * array of png_ptr->width pixels.  If the image is not interlaced or this
- * is the final pass this just does a png_memcpy, otherwise the "display" flag
+ * is the final pass this just does a memcpy, otherwise the "display" flag
  * is used to determine whether to copy pixels that are not in the current pass.
  *
  * Because 'png_do_read_interlace' (below) replicates pixels this allows this
@@ -981,8 +1142,8 @@ PNG_EXTERN void png_write_start_row PNGARG((png_structp png_ptr));
 #ifndef PNG_USE_COMPILE_TIME_MASKS
 #  define PNG_USE_COMPILE_TIME_MASKS 1
 #endif
-PNG_EXTERN void png_combine_row PNGARG((png_structp png_ptr, png_bytep row,
-    int display));
+PNG_INTERNAL_FUNCTION(void,png_combine_row,(png_const_structrp png_ptr,
+    png_bytep row, int display),PNG_EMPTY);
 
 #ifdef PNG_READ_INTERLACING_SUPPORTED
 /* Expand an interlaced row: the 'row_info' describes the pass data that has
@@ -991,188 +1152,99 @@ PNG_EXTERN void png_combine_row PNGARG((png_structp png_ptr, png_bytep row,
  * the pixels are *replicated* to the intervening space.  This is essential for
  * the correct operation of png_combine_row, above.
  */
-PNG_EXTERN void png_do_read_interlace PNGARG((png_row_infop row_info,
-    png_bytep row, int pass, png_uint_32 transformations));
+PNG_INTERNAL_FUNCTION(void,png_do_read_interlace,(png_row_infop row_info,
+    png_bytep row, int pass, png_uint_32 transformations),PNG_EMPTY);
 #endif
 
 /* GRR TO DO (2.0 or whenever):  simplify other internal calling interfaces */
 
 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
 /* Grab pixels out of a row for an interlaced pass */
-PNG_EXTERN void png_do_write_interlace PNGARG((png_row_infop row_info,
-    png_bytep row, int pass));
+PNG_INTERNAL_FUNCTION(void,png_do_write_interlace,(png_row_infop row_info,
+    png_bytep row, int pass),PNG_EMPTY);
 #endif
 
 /* Unfilter a row: check the filter value before calling this, there is no point
  * calling it for PNG_FILTER_VALUE_NONE.
  */
-PNG_EXTERN void png_read_filter_row PNGARG((png_structp pp, png_row_infop row_info,
-    png_bytep row, png_const_bytep prev_row, int filter));
-
-PNG_EXTERN void png_read_filter_row_up_neon PNGARG((png_row_infop row_info,
-    png_bytep row, png_const_bytep prev_row));
-PNG_EXTERN void png_read_filter_row_sub3_neon PNGARG((png_row_infop row_info,
-    png_bytep row, png_const_bytep prev_row));
-PNG_EXTERN void png_read_filter_row_sub4_neon PNGARG((png_row_infop row_info,
-    png_bytep row, png_const_bytep prev_row));
-PNG_EXTERN void png_read_filter_row_avg3_neon PNGARG((png_row_infop row_info,
-    png_bytep row, png_const_bytep prev_row));
-PNG_EXTERN void png_read_filter_row_avg4_neon PNGARG((png_row_infop row_info,
-    png_bytep row, png_const_bytep prev_row));
-PNG_EXTERN void png_read_filter_row_paeth3_neon PNGARG((png_row_infop row_info,
-    png_bytep row, png_const_bytep prev_row));
-PNG_EXTERN void png_read_filter_row_paeth4_neon PNGARG((png_row_infop row_info,
-    png_bytep row, png_const_bytep prev_row));
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row,(png_structrp pp, png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row, int filter),PNG_EMPTY);
+
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_up_neon,(png_row_infop row_info,
+    png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_neon,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_neon,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_neon,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_neon,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_neon,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_neon,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 
 /* Choose the best filter to use and filter the row data */
-PNG_EXTERN void png_write_find_filter PNGARG((png_structp png_ptr,
-    png_row_infop row_info));
+PNG_INTERNAL_FUNCTION(void,png_write_find_filter,(png_structrp png_ptr,
+    png_row_infop row_info),PNG_EMPTY);
+
+#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
+PNG_INTERNAL_FUNCTION(void,png_read_IDAT_data,(png_structrp png_ptr,
+   png_bytep output, png_alloc_size_t avail_out),PNG_EMPTY);
+   /* Read 'avail_out' bytes of data from the IDAT stream.  If the output buffer
+    * is NULL the function checks, instead, for the end of the stream.  In this
+    * case a benign error will be issued if the stream end is not found or if
+    * extra data has to be consumed.
+    */
+PNG_INTERNAL_FUNCTION(void,png_read_finish_IDAT,(png_structrp png_ptr),
+   PNG_EMPTY);
+   /* This cleans up when the IDAT LZ stream does not end when the last image
+    * byte is read; there is still some pending input.
+    */
 
-/* Finish a row while reading, dealing with interlacing passes, etc. */
-PNG_EXTERN void png_read_finish_row PNGARG((png_structp png_ptr));
+PNG_INTERNAL_FUNCTION(void,png_read_finish_row,(png_structrp png_ptr),
+   PNG_EMPTY);
+   /* Finish a row while reading, dealing with interlacing passes, etc. */
+#endif /* SEQUENTIAL_READ */
 
 /* Initialize the row buffers, etc. */
-PNG_EXTERN void png_read_start_row PNGARG((png_structp png_ptr));
+PNG_INTERNAL_FUNCTION(void,png_read_start_row,(png_structrp png_ptr),PNG_EMPTY);
 
 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
 /* Optional call to update the users info structure */
-PNG_EXTERN void png_read_transform_info PNGARG((png_structp png_ptr,
-    png_infop info_ptr));
-#endif
-
-/* These are the functions that do the transformations */
-#ifdef PNG_READ_FILLER_SUPPORTED
-PNG_EXTERN void png_do_read_filler PNGARG((png_row_infop row_info,
-    png_bytep row, png_uint_32 filler, png_uint_32 flags));
-#endif
-
-#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
-PNG_EXTERN void png_do_read_swap_alpha PNGARG((png_row_infop row_info,
-    png_bytep row));
-#endif
-
-#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
-PNG_EXTERN void png_do_write_swap_alpha PNGARG((png_row_infop row_info,
-    png_bytep row));
-#endif
-
-#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
-PNG_EXTERN void png_do_read_invert_alpha PNGARG((png_row_infop row_info,
-    png_bytep row));
-#endif
-
-#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
-PNG_EXTERN void png_do_write_invert_alpha PNGARG((png_row_infop row_info,
-    png_bytep row));
+PNG_INTERNAL_FUNCTION(void,png_read_transform_info,(png_structrp png_ptr,
+    png_inforp info_ptr),PNG_EMPTY);
 #endif
 
+/* Shared transform functions, defined in pngtran.c */
 #if defined(PNG_WRITE_FILLER_SUPPORTED) || \
     defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
-PNG_EXTERN void png_do_strip_channel PNGARG((png_row_infop row_info,
-    png_bytep row, int at_start));
+PNG_INTERNAL_FUNCTION(void,png_do_strip_channel,(png_row_infop row_info,
+    png_bytep row, int at_start),PNG_EMPTY);
 #endif
 
 #ifdef PNG_16BIT_SUPPORTED
 #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
-PNG_EXTERN void png_do_swap PNGARG((png_row_infop row_info,
-    png_bytep row));
+PNG_INTERNAL_FUNCTION(void,png_do_swap,(png_row_infop row_info,
+    png_bytep row),PNG_EMPTY);
 #endif
 #endif
 
 #if defined(PNG_READ_PACKSWAP_SUPPORTED) || \
     defined(PNG_WRITE_PACKSWAP_SUPPORTED)
-PNG_EXTERN void png_do_packswap PNGARG((png_row_infop row_info,
-    png_bytep row));
-#endif
-
-#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
-PNG_EXTERN int png_do_rgb_to_gray PNGARG((png_structp png_ptr,
-    png_row_infop row_info, png_bytep row));
-#endif
-
-#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
-PNG_EXTERN void png_do_gray_to_rgb PNGARG((png_row_infop row_info,
-    png_bytep row));
-#endif
-
-#ifdef PNG_READ_PACK_SUPPORTED
-PNG_EXTERN void png_do_unpack PNGARG((png_row_infop row_info,
-    png_bytep row));
-#endif
-
-#ifdef PNG_READ_SHIFT_SUPPORTED
-PNG_EXTERN void png_do_unshift PNGARG((png_row_infop row_info,
-    png_bytep row, png_const_color_8p sig_bits));
+PNG_INTERNAL_FUNCTION(void,png_do_packswap,(png_row_infop row_info,
+    png_bytep row),PNG_EMPTY);
 #endif
 
 #if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
-PNG_EXTERN void png_do_invert PNGARG((png_row_infop row_info,
-    png_bytep row));
-#endif
-
-#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
-PNG_EXTERN void png_do_scale_16_to_8 PNGARG((png_row_infop row_info,
-    png_bytep row));
-#endif
-
-#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
-PNG_EXTERN void png_do_chop PNGARG((png_row_infop row_info,
-    png_bytep row));
-#endif
-
-#ifdef PNG_READ_QUANTIZE_SUPPORTED
-PNG_EXTERN void png_do_quantize PNGARG((png_row_infop row_info,
-    png_bytep row, png_const_bytep palette_lookup,
-    png_const_bytep quantize_lookup));
-
-#  ifdef PNG_CORRECT_PALETTE_SUPPORTED
-PNG_EXTERN void png_correct_palette PNGARG((png_structp png_ptr,
-    png_colorp palette, int num_palette));
-#  endif
+PNG_INTERNAL_FUNCTION(void,png_do_invert,(png_row_infop row_info,
+    png_bytep row),PNG_EMPTY);
 #endif
 
 #if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
-PNG_EXTERN void png_do_bgr PNGARG((png_row_infop row_info,
-    png_bytep row));
-#endif
-
-#ifdef PNG_WRITE_PACK_SUPPORTED
-PNG_EXTERN void png_do_pack PNGARG((png_row_infop row_info,
-   png_bytep row, png_uint_32 bit_depth));
-#endif
-
-#ifdef PNG_WRITE_SHIFT_SUPPORTED
-PNG_EXTERN void png_do_shift PNGARG((png_row_infop row_info,
-    png_bytep row, png_const_color_8p bit_depth));
-#endif
-
-#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
-    defined(PNG_READ_ALPHA_MODE_SUPPORTED)
-PNG_EXTERN void png_do_compose PNGARG((png_row_infop row_info,
-    png_bytep row, png_structp png_ptr));
-#endif
-
-#ifdef PNG_READ_GAMMA_SUPPORTED
-PNG_EXTERN void png_do_gamma PNGARG((png_row_infop row_info,
-    png_bytep row, png_structp png_ptr));
-#endif
-
-#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
-PNG_EXTERN void png_do_encode_alpha PNGARG((png_row_infop row_info,
-   png_bytep row, png_structp png_ptr));
-#endif
-
-#ifdef PNG_READ_EXPAND_SUPPORTED
-PNG_EXTERN void png_do_expand_palette PNGARG((png_row_infop row_info,
-    png_bytep row, png_const_colorp palette, png_const_bytep trans,
-    int num_trans));
-PNG_EXTERN void png_do_expand PNGARG((png_row_infop row_info,
-    png_bytep row, png_const_color_16p trans_color));
-#endif
-
-#ifdef PNG_READ_EXPAND_16_SUPPORTED
-PNG_EXTERN void png_do_expand_16 PNGARG((png_row_infop row_info,
-    png_bytep row));
+PNG_INTERNAL_FUNCTION(void,png_do_bgr,(png_row_infop row_info,
+    png_bytep row),PNG_EMPTY);
 #endif
 
 /* The following decodes the appropriate chunks, and does error correction,
@@ -1180,256 +1252,283 @@ PNG_EXTERN void png_do_expand_16 PNGARG((png_row_infop row_info,
  */
 
 /* Decode the IHDR chunk */
-PNG_EXTERN void png_handle_IHDR PNGARG((png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 length));
-PNG_EXTERN void png_handle_PLTE PNGARG((png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 length));
-PNG_EXTERN void png_handle_IEND PNGARG((png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 length));
+PNG_INTERNAL_FUNCTION(void,png_handle_IHDR,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_handle_PLTE,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_handle_IEND,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
 
 #ifdef PNG_READ_bKGD_SUPPORTED
-PNG_EXTERN void png_handle_bKGD PNGARG((png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 length));
+PNG_INTERNAL_FUNCTION(void,png_handle_bKGD,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
 #endif
 
 #ifdef PNG_READ_cHRM_SUPPORTED
-PNG_EXTERN void png_handle_cHRM PNGARG((png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 length));
+PNG_INTERNAL_FUNCTION(void,png_handle_cHRM,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
 #endif
 
 #ifdef PNG_READ_gAMA_SUPPORTED
-PNG_EXTERN void png_handle_gAMA PNGARG((png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 length));
+PNG_INTERNAL_FUNCTION(void,png_handle_gAMA,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
 #endif
 
 #ifdef PNG_READ_hIST_SUPPORTED
-PNG_EXTERN void png_handle_hIST PNGARG((png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 length));
+PNG_INTERNAL_FUNCTION(void,png_handle_hIST,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
 #endif
 
 #ifdef PNG_READ_iCCP_SUPPORTED
-PNG_EXTERN void png_handle_iCCP PNGARG((png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 length));
-#endif /* PNG_READ_iCCP_SUPPORTED */
+PNG_INTERNAL_FUNCTION(void,png_handle_iCCP,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
+#endif /* READ_iCCP */
 
 #ifdef PNG_READ_iTXt_SUPPORTED
-PNG_EXTERN void png_handle_iTXt PNGARG((png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 length));
+PNG_INTERNAL_FUNCTION(void,png_handle_iTXt,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
 #endif
 
 #ifdef PNG_READ_oFFs_SUPPORTED
-PNG_EXTERN void png_handle_oFFs PNGARG((png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 length));
+PNG_INTERNAL_FUNCTION(void,png_handle_oFFs,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
 #endif
 
 #ifdef PNG_READ_pCAL_SUPPORTED
-PNG_EXTERN void png_handle_pCAL PNGARG((png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 length));
+PNG_INTERNAL_FUNCTION(void,png_handle_pCAL,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
 #endif
 
 #ifdef PNG_READ_pHYs_SUPPORTED
-PNG_EXTERN void png_handle_pHYs PNGARG((png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 length));
+PNG_INTERNAL_FUNCTION(void,png_handle_pHYs,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
 #endif
 
 #ifdef PNG_READ_sBIT_SUPPORTED
-PNG_EXTERN void png_handle_sBIT PNGARG((png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 length));
+PNG_INTERNAL_FUNCTION(void,png_handle_sBIT,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
 #endif
 
 #ifdef PNG_READ_sCAL_SUPPORTED
-PNG_EXTERN void png_handle_sCAL PNGARG((png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 length));
+PNG_INTERNAL_FUNCTION(void,png_handle_sCAL,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
 #endif
 
 #ifdef PNG_READ_sPLT_SUPPORTED
-PNG_EXTERN void png_handle_sPLT PNGARG((png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 length));
-#endif /* PNG_READ_sPLT_SUPPORTED */
+PNG_INTERNAL_FUNCTION(void,png_handle_sPLT,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
+#endif /* READ_sPLT */
 
 #ifdef PNG_READ_sRGB_SUPPORTED
-PNG_EXTERN void png_handle_sRGB PNGARG((png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 length));
+PNG_INTERNAL_FUNCTION(void,png_handle_sRGB,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
 #endif
 
 #ifdef PNG_READ_tEXt_SUPPORTED
-PNG_EXTERN void png_handle_tEXt PNGARG((png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 length));
+PNG_INTERNAL_FUNCTION(void,png_handle_tEXt,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
 #endif
 
 #ifdef PNG_READ_tIME_SUPPORTED
-PNG_EXTERN void png_handle_tIME PNGARG((png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 length));
+PNG_INTERNAL_FUNCTION(void,png_handle_tIME,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
 #endif
 
 #ifdef PNG_READ_tRNS_SUPPORTED
-PNG_EXTERN void png_handle_tRNS PNGARG((png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 length));
+PNG_INTERNAL_FUNCTION(void,png_handle_tRNS,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
 #endif
 
 #ifdef PNG_READ_zTXt_SUPPORTED
-PNG_EXTERN void png_handle_zTXt PNGARG((png_structp png_ptr, png_infop info_ptr,
-    png_uint_32 length));
+PNG_INTERNAL_FUNCTION(void,png_handle_zTXt,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
 #endif
 
-#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
-PNG_EXTERN void png_handle_unknown PNGARG((png_structp png_ptr,
-    png_infop info_ptr, png_uint_32 length));
-#endif
+PNG_INTERNAL_FUNCTION(void,png_check_chunk_name,(png_structrp png_ptr,
+    png_uint_32 chunk_name),PNG_EMPTY);
 
-PNG_EXTERN void png_check_chunk_name PNGARG((png_structp png_ptr,
-    png_uint_32 chunk_name));
+PNG_INTERNAL_FUNCTION(void,png_handle_unknown,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length, int keep),PNG_EMPTY);
+   /* This is the function that gets called for unknown chunks.  The 'keep'
+    * argument is either non-zero for a known chunk that has been set to be
+    * handled as unknown or zero for an unknown chunk.  By default the function
+    * just skips the chunk or errors out if it is critical.
+    */
 
-#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
-/* Exactly as png_handle_as_unknown() except that the argument is a 32-bit chunk
- * name, not a string.
- */
-PNG_EXTERN int png_chunk_unknown_handling PNGARG((png_structp png_ptr,
-    png_uint_32 chunk_name));
-#endif
+#if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) ||\
+    defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
+PNG_INTERNAL_FUNCTION(int,png_chunk_unknown_handling,
+    (png_const_structrp png_ptr, png_uint_32 chunk_name),PNG_EMPTY);
+   /* Exactly as the API png_handle_as_unknown() except that the argument is a
+    * 32-bit chunk name, not a string.
+    */
+#endif /* READ_UNKNOWN_CHUNKS || HANDLE_AS_UNKNOWN */
 
 /* Handle the transformations for reading and writing */
 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
-PNG_EXTERN void png_do_read_transformations PNGARG((png_structp png_ptr,
-   png_row_infop row_info));
+PNG_INTERNAL_FUNCTION(void,png_do_read_transformations,(png_structrp png_ptr,
+   png_row_infop row_info),PNG_EMPTY);
 #endif
 #ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
-PNG_EXTERN void png_do_write_transformations PNGARG((png_structp png_ptr,
-   png_row_infop row_info));
+PNG_INTERNAL_FUNCTION(void,png_do_write_transformations,(png_structrp png_ptr,
+   png_row_infop row_info),PNG_EMPTY);
 #endif
 
 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
-PNG_EXTERN void png_init_read_transformations PNGARG((png_structp png_ptr));
+PNG_INTERNAL_FUNCTION(void,png_init_read_transformations,(png_structrp png_ptr),
+    PNG_EMPTY);
 #endif
 
 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
-PNG_EXTERN void png_push_read_chunk PNGARG((png_structp png_ptr,
-    png_infop info_ptr));
-PNG_EXTERN void png_push_read_sig PNGARG((png_structp png_ptr,
-    png_infop info_ptr));
-PNG_EXTERN void png_push_check_crc PNGARG((png_structp png_ptr));
-PNG_EXTERN void png_push_crc_skip PNGARG((png_structp png_ptr,
-    png_uint_32 length));
-PNG_EXTERN void png_push_crc_finish PNGARG((png_structp png_ptr));
-PNG_EXTERN void png_push_save_buffer PNGARG((png_structp png_ptr));
-PNG_EXTERN void png_push_restore_buffer PNGARG((png_structp png_ptr,
-    png_bytep buffer, png_size_t buffer_length));
-PNG_EXTERN void png_push_read_IDAT PNGARG((png_structp png_ptr));
-PNG_EXTERN void png_process_IDAT_data PNGARG((png_structp png_ptr,
-    png_bytep buffer, png_size_t buffer_length));
-PNG_EXTERN void png_push_process_row PNGARG((png_structp png_ptr));
-PNG_EXTERN void png_push_handle_unknown PNGARG((png_structp png_ptr,
-   png_infop info_ptr, png_uint_32 length));
-PNG_EXTERN void png_push_have_info PNGARG((png_structp png_ptr,
-   png_infop info_ptr));
-PNG_EXTERN void png_push_have_end PNGARG((png_structp png_ptr,
-   png_infop info_ptr));
-PNG_EXTERN void png_push_have_row PNGARG((png_structp png_ptr, png_bytep row));
-PNG_EXTERN void png_push_read_end PNGARG((png_structp png_ptr,
-    png_infop info_ptr));
-PNG_EXTERN void png_process_some_data PNGARG((png_structp png_ptr,
-    png_infop info_ptr));
-PNG_EXTERN void png_read_push_finish_row PNGARG((png_structp png_ptr));
+PNG_INTERNAL_FUNCTION(void,png_push_read_chunk,(png_structrp png_ptr,
+    png_inforp info_ptr),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_push_read_sig,(png_structrp png_ptr,
+    png_inforp info_ptr),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_push_check_crc,(png_structrp png_ptr),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_push_crc_skip,(png_structrp png_ptr,
+    png_uint_32 length),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_push_crc_finish,(png_structrp png_ptr),
+    PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_push_save_buffer,(png_structrp png_ptr),
+    PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_push_restore_buffer,(png_structrp png_ptr,
+    png_bytep buffer, png_size_t buffer_length),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_push_read_IDAT,(png_structrp png_ptr),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_process_IDAT_data,(png_structrp png_ptr,
+    png_bytep buffer, png_size_t buffer_length),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_push_process_row,(png_structrp png_ptr),
+    PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_push_handle_unknown,(png_structrp png_ptr,
+   png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_push_have_info,(png_structrp png_ptr,
+   png_inforp info_ptr),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_push_have_end,(png_structrp png_ptr,
+   png_inforp info_ptr),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_push_have_row,(png_structrp png_ptr,
+     png_bytep row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_push_read_end,(png_structrp png_ptr,
+    png_inforp info_ptr),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_process_some_data,(png_structrp png_ptr,
+    png_inforp info_ptr),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_push_finish_row,(png_structrp png_ptr),
+    PNG_EMPTY);
 #  ifdef PNG_READ_tEXt_SUPPORTED
-PNG_EXTERN void png_push_handle_tEXt PNGARG((png_structp png_ptr,
-    png_infop info_ptr, png_uint_32 length));
-PNG_EXTERN void png_push_read_tEXt PNGARG((png_structp png_ptr,
-    png_infop info_ptr));
+PNG_INTERNAL_FUNCTION(void,png_push_handle_tEXt,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_push_read_tEXt,(png_structrp png_ptr,
+    png_inforp info_ptr),PNG_EMPTY);
 #  endif
 #  ifdef PNG_READ_zTXt_SUPPORTED
-PNG_EXTERN void png_push_handle_zTXt PNGARG((png_structp png_ptr,
-    png_infop info_ptr, png_uint_32 length));
-PNG_EXTERN void png_push_read_zTXt PNGARG((png_structp png_ptr,
-    png_infop info_ptr));
+PNG_INTERNAL_FUNCTION(void,png_push_handle_zTXt,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_push_read_zTXt,(png_structrp png_ptr,
+    png_inforp info_ptr),PNG_EMPTY);
 #  endif
 #  ifdef PNG_READ_iTXt_SUPPORTED
-PNG_EXTERN void png_push_handle_iTXt PNGARG((png_structp png_ptr,
-    png_infop info_ptr, png_uint_32 length));
-PNG_EXTERN void png_push_read_iTXt PNGARG((png_structp png_ptr,
-    png_infop info_ptr));
+PNG_INTERNAL_FUNCTION(void,png_push_handle_iTXt,(png_structrp png_ptr,
+    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_push_read_iTXt,(png_structrp png_ptr,
+    png_inforp info_ptr),PNG_EMPTY);
 #  endif
 
-#endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
+#endif /* PROGRESSIVE_READ */
 
-#ifdef PNG_MNG_FEATURES_SUPPORTED
-PNG_EXTERN void png_do_read_intrapixel PNGARG((png_row_infop row_info,
-    png_bytep row));
-PNG_EXTERN void png_do_write_intrapixel PNGARG((png_row_infop row_info,
-    png_bytep row));
-#endif
+/* Added at libpng version 1.6.0 */
+#ifdef PNG_GAMMA_SUPPORTED
+PNG_INTERNAL_FUNCTION(void,png_colorspace_set_gamma,(png_const_structrp png_ptr,
+    png_colorspacerp colorspace, png_fixed_point gAMA), PNG_EMPTY);
+   /* Set the colorspace gamma with a value provided by the application or by
+    * the gAMA chunk on read.  The value will override anything set by an ICC
+    * profile.
+    */
 
-/* Added at libpng version 1.4.0 */
-#ifdef PNG_CHECK_cHRM_SUPPORTED
-PNG_EXTERN int png_check_cHRM_fixed PNGARG((png_structp png_ptr,
-    png_fixed_point int_white_x, png_fixed_point int_white_y,
-    png_fixed_point int_red_x, png_fixed_point int_red_y, png_fixed_point
-    int_green_x, png_fixed_point int_green_y, png_fixed_point int_blue_x,
-    png_fixed_point int_blue_y));
-#endif
+PNG_INTERNAL_FUNCTION(void,png_colorspace_sync_info,(png_const_structrp png_ptr,
+    png_inforp info_ptr), PNG_EMPTY);
+    /* Synchronize the info 'valid' flags with the colorspace */
 
-#ifdef PNG_CHECK_cHRM_SUPPORTED
-/* Added at libpng version 1.2.34 and 1.4.0 */
-/* Currently only used by png_check_cHRM_fixed */
-PNG_EXTERN void png_64bit_product PNGARG((long v1, long v2,
-    unsigned long *hi_product, unsigned long *lo_product));
+PNG_INTERNAL_FUNCTION(void,png_colorspace_sync,(png_const_structrp png_ptr,
+    png_inforp info_ptr), PNG_EMPTY);
+    /* Copy the png_struct colorspace to the info_struct and call the above to
+     * synchronize the flags.  Checks for NULL info_ptr and does nothing.
+     */
 #endif
 
-#ifdef PNG_cHRM_SUPPORTED
-/* Added at libpng version 1.5.5 */
-typedef struct png_xy
-{
-   png_fixed_point redx, redy;
-   png_fixed_point greenx, greeny;
-   png_fixed_point bluex, bluey;
-   png_fixed_point whitex, whitey;
-} png_xy;
-
-typedef struct png_XYZ
-{
-   png_fixed_point redX, redY, redZ;
-   png_fixed_point greenX, greenY, greenZ;
-   png_fixed_point blueX, blueY, blueZ;
-} png_XYZ;
-
-/* The conversion APIs return 0 on success, non-zero on a parameter error. They
- * allow conversion between the above representations of a color encoding.  When
- * converting from XYZ end points to chromaticities the absolute magnitude of
- * the end points is lost, when converting back the sum of the Y values of the
- * three end points will be 1.0
+/* Added at libpng version 1.4.0 */
+#ifdef PNG_COLORSPACE_SUPPORTED
+/* These internal functions are for maintaining the colorspace structure within
+ * a png_info or png_struct (or, indeed, both).
  */
-PNG_EXTERN int png_xy_from_XYZ PNGARG((png_xy *xy, png_XYZ XYZ));
-PNG_EXTERN int png_XYZ_from_xy PNGARG((png_XYZ *XYZ, png_xy xy));
-PNG_EXTERN int png_XYZ_from_xy_checked PNGARG((png_structp png_ptr,
-   png_XYZ *XYZ, png_xy xy));
+PNG_INTERNAL_FUNCTION(int,png_colorspace_set_chromaticities,
+   (png_const_structrp png_ptr, png_colorspacerp colorspace, const png_xy *xy,
+    int preferred), PNG_EMPTY);
+
+PNG_INTERNAL_FUNCTION(int,png_colorspace_set_endpoints,
+   (png_const_structrp png_ptr, png_colorspacerp colorspace, const png_XYZ *XYZ,
+    int preferred), PNG_EMPTY);
+
+#ifdef PNG_sRGB_SUPPORTED
+PNG_INTERNAL_FUNCTION(int,png_colorspace_set_sRGB,(png_const_structrp png_ptr,
+   png_colorspacerp colorspace, int intent), PNG_EMPTY);
+   /* This does set the colorspace gAMA and cHRM values too, but doesn't set the
+    * flags to write them, if it returns false there was a problem and an error
+    * message has already been output (but the colorspace may still need to be
+    * synced to record the invalid flag).
+    */
+#endif /* sRGB */
+
+#ifdef PNG_iCCP_SUPPORTED
+PNG_INTERNAL_FUNCTION(int,png_colorspace_set_ICC,(png_const_structrp png_ptr,
+   png_colorspacerp colorspace, png_const_charp name,
+   png_uint_32 profile_length, png_const_bytep profile, int color_type),
+   PNG_EMPTY);
+   /* The 'name' is used for information only */
+
+/* Routines for checking parts of an ICC profile. */
+PNG_INTERNAL_FUNCTION(int,png_icc_check_length,(png_const_structrp png_ptr,
+   png_colorspacerp colorspace, png_const_charp name,
+   png_uint_32 profile_length), PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(int,png_icc_check_header,(png_const_structrp png_ptr,
+   png_colorspacerp colorspace, png_const_charp name,
+   png_uint_32 profile_length,
+   png_const_bytep profile /* first 132 bytes only */, int color_type),
+   PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(int,png_icc_check_tag_table,(png_const_structrp png_ptr,
+   png_colorspacerp colorspace, png_const_charp name,
+   png_uint_32 profile_length,
+   png_const_bytep profile /* header plus whole tag table */), PNG_EMPTY);
+#ifdef PNG_sRGB_SUPPORTED
+PNG_INTERNAL_FUNCTION(void,png_icc_set_sRGB,(
+   png_const_structrp png_ptr, png_colorspacerp colorspace,
+   png_const_bytep profile, uLong adler), PNG_EMPTY);
+   /* 'adler' is the Adler32 checksum of the uncompressed profile data. It may
+    * be zero to indicate that it is not available.  It is used, if provided,
+    * as a fast check on the profile when checking to see if it is sRGB.
+    */
 #endif
+#endif /* iCCP */
+
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+PNG_INTERNAL_FUNCTION(void,png_colorspace_set_rgb_coefficients,
+   (png_structrp png_ptr), PNG_EMPTY);
+   /* Set the rgb_to_gray coefficients from the colorspace Y values */
+#endif /* READ_RGB_TO_GRAY */
+#endif /* COLORSPACE */
 
 /* Added at libpng version 1.4.0 */
-PNG_EXTERN void png_check_IHDR PNGARG((png_structp png_ptr,
+PNG_INTERNAL_FUNCTION(void,png_check_IHDR,(png_const_structrp png_ptr,
     png_uint_32 width, png_uint_32 height, int bit_depth,
     int color_type, int interlace_type, int compression_type,
-    int filter_type));
+    int filter_type),PNG_EMPTY);
 
 /* Added at libpng version 1.5.10 */
 #if defined(PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED) || \
     defined(PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED)
-PNG_EXTERN void png_do_check_palette_indexes PNGARG((png_structp png_ptr,
-    png_row_infop row_info));
+PNG_INTERNAL_FUNCTION(void,png_do_check_palette_indexes,
+   (png_structrp png_ptr, png_row_infop row_info),PNG_EMPTY);
 #endif
 
-/* Free all memory used by the read (old method - NOT DLL EXPORTED) */
-PNG_EXTERN void png_read_destroy PNGARG((png_structp png_ptr,
-    png_infop info_ptr, png_infop end_info_ptr));
-
-/* Free any memory used in png_ptr struct (old method - NOT DLL EXPORTED) */
-PNG_EXTERN void png_write_destroy PNGARG((png_structp png_ptr));
-
-#ifdef USE_FAR_KEYWORD  /* memory model conversion function */
-PNG_EXTERN void *png_far_to_near PNGARG((png_structp png_ptr, png_voidp ptr,
-    int check));
-#endif /* USE_FAR_KEYWORD */
-
 #if defined(PNG_FLOATING_POINT_SUPPORTED) && defined(PNG_ERROR_TEXT_SUPPORTED)
-PNG_EXTERN PNG_FUNCTION(void, png_fixed_error, (png_structp png_ptr,
+PNG_INTERNAL_FUNCTION(void,png_fixed_error,(png_const_structrp png_ptr,
    png_const_charp name),PNG_NORETURN);
 #endif
 
@@ -1437,8 +1536,8 @@ PNG_EXTERN PNG_FUNCTION(void, png_fixed_error, (png_structp png_ptr,
  * the end.  Always leaves the buffer nul terminated.  Never errors out (and
  * there is no error code.)
  */
-PNG_EXTERN size_t png_safecat(png_charp buffer, size_t bufsize, size_t pos,
-    png_const_charp string);
+PNG_INTERNAL_FUNCTION(size_t,png_safecat,(png_charp buffer, size_t bufsize,
+   size_t pos, png_const_charp string),PNG_EMPTY);
 
 /* Various internal functions to handle formatted warning messages, currently
  * only implemented for warnings.
@@ -1449,8 +1548,8 @@ PNG_EXTERN size_t png_safecat(png_charp buffer, size_t bufsize, size_t pos,
  * Returns the pointer to the start of the formatted string.  This utility only
  * does unsigned values.
  */
-PNG_EXTERN png_charp png_format_number(png_const_charp start, png_charp end,
-   int format, png_alloc_size_t number);
+PNG_INTERNAL_FUNCTION(png_charp,png_format_number,(png_const_charp start,
+   png_charp end, int format, png_alloc_size_t number),PNG_EMPTY);
 
 /* Convenience macro that takes an array: */
 #define PNG_FORMAT_NUMBER(buffer,format,number) \
@@ -1474,7 +1573,7 @@ PNG_EXTERN png_charp png_format_number(png_const_charp start, png_charp end,
 #ifdef PNG_WARNINGS_SUPPORTED
 /* New defines and members adding in libpng-1.5.4 */
 #  define PNG_WARNING_PARAMETER_SIZE 32
-#  define PNG_WARNING_PARAMETER_COUNT 8
+#  define PNG_WARNING_PARAMETER_COUNT 8 /* Maximum 9; see pngerror.c */
 
 /* An l-value of this type has to be passed to the APIs below to cache the
  * values of the parameters to a formatted warning message.
@@ -1482,48 +1581,97 @@ PNG_EXTERN png_charp png_format_number(png_const_charp start, png_charp end,
 typedef char png_warning_parameters[PNG_WARNING_PARAMETER_COUNT][
    PNG_WARNING_PARAMETER_SIZE];
 
-PNG_EXTERN void png_warning_parameter(png_warning_parameters p, int number,
-    png_const_charp string);
-    /* Parameters are limited in size to PNG_WARNING_PARAMETER_SIZE characters,
-     * including the trailing '\0'.
-     */
-PNG_EXTERN void png_warning_parameter_unsigned(png_warning_parameters p,
-    int number, int format, png_alloc_size_t value);
-    /* Use png_alloc_size_t because it is an unsigned type as big as any we
-     * need to output.  Use the following for a signed value.
-     */
-PNG_EXTERN void png_warning_parameter_signed(png_warning_parameters p,
-    int number, int format, png_int_32 value);
-
-PNG_EXTERN void png_formatted_warning(png_structp png_ptr,
-    png_warning_parameters p, png_const_charp message);
-    /* 'message' follows the X/Open approach of using @1, @2 to insert
-     * parameters previously supplied using the above functions.  Errors in
-     * specifying the paramters will simple result in garbage substitutions.
-     */
+PNG_INTERNAL_FUNCTION(void,png_warning_parameter,(png_warning_parameters p,
+   int number, png_const_charp string),PNG_EMPTY);
+   /* Parameters are limited in size to PNG_WARNING_PARAMETER_SIZE characters,
+    * including the trailing '\0'.
+    */
+PNG_INTERNAL_FUNCTION(void,png_warning_parameter_unsigned,
+   (png_warning_parameters p, int number, int format, png_alloc_size_t value),
+   PNG_EMPTY);
+   /* Use png_alloc_size_t because it is an unsigned type as big as any we
+    * need to output.  Use the following for a signed value.
+    */
+PNG_INTERNAL_FUNCTION(void,png_warning_parameter_signed,
+   (png_warning_parameters p, int number, int format, png_int_32 value),
+   PNG_EMPTY);
+
+PNG_INTERNAL_FUNCTION(void,png_formatted_warning,(png_const_structrp png_ptr,
+   png_warning_parameters p, png_const_charp message),PNG_EMPTY);
+   /* 'message' follows the X/Open approach of using @1, @2 to insert
+    * parameters previously supplied using the above functions.  Errors in
+    * specifying the parameters will simply result in garbage substitutions.
+    */
 #endif
 
+#ifdef PNG_BENIGN_ERRORS_SUPPORTED
+/* Application errors (new in 1.6); use these functions (declared below) for
+ * errors in the parameters or order of API function calls on read.  The
+ * 'warning' should be used for an error that can be handled completely; the
+ * 'error' for one which can be handled safely but which may lose application
+ * information or settings.
+ *
+ * By default these both result in a png_error call prior to release, while in a
+ * released version the 'warning' is just a warning.  However if the application
+ * explicitly disables benign errors (explicitly permitting the code to lose
+ * information) they both turn into warnings.
+ *
+ * If benign errors aren't supported they end up as the corresponding base call
+ * (png_warning or png_error.)
+ */
+PNG_INTERNAL_FUNCTION(void,png_app_warning,(png_const_structrp png_ptr,
+   png_const_charp message),PNG_EMPTY);
+   /* The application provided invalid parameters to an API function or called
+    * an API function at the wrong time, libpng can completely recover.
+    */
+
+PNG_INTERNAL_FUNCTION(void,png_app_error,(png_const_structrp png_ptr,
+   png_const_charp message),PNG_EMPTY);
+   /* As above but libpng will ignore the call, or attempt some other partial
+    * recovery from the error.
+    */
+#else
+#  define png_app_warning(pp,s) png_warning(pp,s)
+#  define png_app_error(pp,s) png_error(pp,s)
+#endif
+
+PNG_INTERNAL_FUNCTION(void,png_chunk_report,(png_const_structrp png_ptr,
+   png_const_charp message, int error),PNG_EMPTY);
+   /* Report a recoverable issue in chunk data.  On read this is used to report
+    * a problem found while reading a particular chunk and the
+    * png_chunk_benign_error or png_chunk_warning function is used as
+    * appropriate.  On write this is used to report an error that comes from
+    * data set via an application call to a png_set_ API and png_app_error or
+    * png_app_warning is used as appropriate.
+    *
+    * The 'error' parameter must have one of the following values:
+    */
+#define PNG_CHUNK_WARNING     0 /* never an error */
+#define PNG_CHUNK_WRITE_ERROR 1 /* an error only on write */
+#define PNG_CHUNK_ERROR       2 /* always an error */
+
 /* ASCII to FP interfaces, currently only implemented if sCAL
  * support is required.
  */
-#if defined(PNG_READ_sCAL_SUPPORTED)
+#if defined(PNG_sCAL_SUPPORTED)
 /* MAX_DIGITS is actually the maximum number of characters in an sCAL
  * width or height, derived from the precision (number of significant
- * digits - a build time settable option) and assumpitions about the
+ * digits - a build time settable option) and assumptions about the
  * maximum ridiculous exponent.
  */
 #define PNG_sCAL_MAX_DIGITS (PNG_sCAL_PRECISION+1/*.*/+1/*E*/+10/*exponent*/)
 
 #ifdef PNG_FLOATING_POINT_SUPPORTED
-PNG_EXTERN void png_ascii_from_fp PNGARG((png_structp png_ptr, png_charp ascii,
-    png_size_t size, double fp, unsigned int precision));
+PNG_INTERNAL_FUNCTION(void,png_ascii_from_fp,(png_const_structrp png_ptr,
+   png_charp ascii, png_size_t size, double fp, unsigned int precision),
+   PNG_EMPTY);
 #endif /* FLOATING_POINT */
 
 #ifdef PNG_FIXED_POINT_SUPPORTED
-PNG_EXTERN void png_ascii_from_fixed PNGARG((png_structp png_ptr,
-    png_charp ascii, png_size_t size, png_fixed_point fp));
+PNG_INTERNAL_FUNCTION(void,png_ascii_from_fixed,(png_const_structrp png_ptr,
+   png_charp ascii, png_size_t size, png_fixed_point fp),PNG_EMPTY);
 #endif /* FIXED_POINT */
-#endif /* READ_sCAL */
+#endif /* sCAL */
 
 #if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED)
 /* An internal API to validate the format of a floating point number.
@@ -1547,7 +1695,7 @@ PNG_EXTERN void png_ascii_from_fixed PNGARG((png_structp png_ptr,
  * NOTE: The dangling E problem.
  *   There is a PNG valid floating point number in the following:
  *
- *       PNG floating point numb1.ers are not greedy.
+ *       PNG floating point numbers are not greedy.
  *
  *   Working this out requires *TWO* character lookahead (because of the
  *   sign), the parser does not do this - it will fail at the 'r' - this
@@ -1598,14 +1746,14 @@ PNG_EXTERN void png_ascii_from_fixed PNGARG((png_structp png_ptr,
 #define PNG_FP_IS_POSITIVE(state) (((state) & PNG_FP_NZ_MASK) == PNG_FP_Z_MASK)
 #define PNG_FP_IS_NEGATIVE(state) (((state) & PNG_FP_NZ_MASK) == PNG_FP_NZ_MASK)
 
-/* The actual parser.  This can be called repeatedly, it updates
+/* The actual parser.  This can be called repeatedly. It updates
  * the index into the string and the state variable (which must
- * be initialzed to 0).  It returns a result code, as above.  There
+ * be initialized to 0).  It returns a result code, as above.  There
  * is no point calling the parser any more if it fails to advance to
  * the end of the string - it is stuck on an invalid character (or
  * terminated by '\0').
  *
- * Note that the pointer will consume an E or even an E+ then leave
+ * Note that the pointer will consume an E or even an E+ and then leave
  * a 'maybe' state even though a preceding integer.fraction is valid.
  * The PNG_FP_WAS_VALID flag indicates that a preceding substring was
  * a valid number.  It's possible to recover from this by calling
@@ -1613,8 +1761,8 @@ PNG_EXTERN void png_ascii_from_fixed PNGARG((png_structp png_ptr,
  * that omits the last character (i.e. set the size to the index of
  * the problem character.)  This has not been tested within libpng.
  */
-PNG_EXTERN int png_check_fp_number PNGARG((png_const_charp string,
-    png_size_t size, int *statep, png_size_tp whereami));
+PNG_INTERNAL_FUNCTION(int,png_check_fp_number,(png_const_charp string,
+   png_size_t size, int *statep, png_size_tp whereami),PNG_EMPTY);
 
 /* This is the same but it checks a complete string and returns true
  * only if it just contains a floating point number.  As of 1.5.4 this
@@ -1622,11 +1770,11 @@ PNG_EXTERN int png_check_fp_number PNGARG((png_const_charp string,
  * it was valid (otherwise it returns 0.)  This can be used for testing
  * for negative or zero values using the sticky flag.
  */
-PNG_EXTERN int png_check_fp_string PNGARG((png_const_charp string,
-    png_size_t size));
+PNG_INTERNAL_FUNCTION(int,png_check_fp_string,(png_const_charp string,
+   png_size_t size),PNG_EMPTY);
 #endif /* pCAL || sCAL */
 
-#if defined(PNG_READ_GAMMA_SUPPORTED) ||\
+#if defined(PNG_GAMMA_SUPPORTED) ||\
     defined(PNG_INCH_CONVERSIONS_SUPPORTED) || defined(PNG_READ_pHYs_SUPPORTED)
 /* Added at libpng version 1.5.0 */
 /* This is a utility to provide a*times/div (rounded) and indicate
@@ -1634,29 +1782,37 @@ PNG_EXTERN int png_check_fp_string PNGARG((png_const_charp string,
  * for overflow, true (1) if no overflow, in which case *res
  * holds the result.
  */
-PNG_EXTERN int png_muldiv PNGARG((png_fixed_point_p res, png_fixed_point a,
-    png_int_32 multiplied_by, png_int_32 divided_by));
+PNG_INTERNAL_FUNCTION(int,png_muldiv,(png_fixed_point_p res, png_fixed_point a,
+   png_int_32 multiplied_by, png_int_32 divided_by),PNG_EMPTY);
 #endif
 
 #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_INCH_CONVERSIONS_SUPPORTED)
 /* Same deal, but issue a warning on overflow and return 0. */
-PNG_EXTERN png_fixed_point png_muldiv_warn PNGARG((png_structp png_ptr,
-    png_fixed_point a, png_int_32 multiplied_by, png_int_32 divided_by));
+PNG_INTERNAL_FUNCTION(png_fixed_point,png_muldiv_warn,
+   (png_const_structrp png_ptr, png_fixed_point a, png_int_32 multiplied_by,
+   png_int_32 divided_by),PNG_EMPTY);
 #endif
 
-#ifdef PNG_READ_GAMMA_SUPPORTED
+#ifdef PNG_GAMMA_SUPPORTED
 /* Calculate a reciprocal - used for gamma values.  This returns
- * 0 if the argument is 0 in order to maintain an undefined value,
+ * 0 if the argument is 0 in order to maintain an undefined value;
  * there are no warnings.
  */
-PNG_EXTERN png_fixed_point png_reciprocal PNGARG((png_fixed_point a));
+PNG_INTERNAL_FUNCTION(png_fixed_point,png_reciprocal,(png_fixed_point a),
+   PNG_EMPTY);
 
+#ifdef PNG_READ_GAMMA_SUPPORTED
 /* The same but gives a reciprocal of the product of two fixed point
  * values.  Accuracy is suitable for gamma calculations but this is
- * not exact - use png_muldiv for that.
+ * not exact - use png_muldiv for that.  Only required at present on read.
  */
-PNG_EXTERN png_fixed_point png_reciprocal2 PNGARG((png_fixed_point a,
-    png_fixed_point b));
+PNG_INTERNAL_FUNCTION(png_fixed_point,png_reciprocal2,(png_fixed_point a,
+   png_fixed_point b),PNG_EMPTY);
+#endif
+
+/* Return true if the gamma value is significantly different from 1.0 */
+PNG_INTERNAL_FUNCTION(int,png_gamma_significant,(png_fixed_point gamma_value),
+   PNG_EMPTY);
 #endif
 
 #ifdef PNG_READ_GAMMA_SUPPORTED
@@ -1667,19 +1823,93 @@ PNG_EXTERN png_fixed_point png_reciprocal2 PNGARG((png_fixed_point a,
  * While the input is an 'unsigned' value it must actually be the
  * correct bit value - 0..255 or 0..65535 as required.
  */
-PNG_EXTERN png_uint_16 png_gamma_correct PNGARG((png_structp png_ptr,
-    unsigned int value, png_fixed_point gamma_value));
-PNG_EXTERN int png_gamma_significant PNGARG((png_fixed_point gamma_value));
-PNG_EXTERN png_uint_16 png_gamma_16bit_correct PNGARG((unsigned int value,
-    png_fixed_point gamma_value));
-PNG_EXTERN png_byte png_gamma_8bit_correct PNGARG((unsigned int value,
-    png_fixed_point gamma_value));
-PNG_EXTERN void png_destroy_gamma_table(png_structp png_ptr);
-PNG_EXTERN void png_build_gamma_table PNGARG((png_structp png_ptr,
-    int bit_depth));
+PNG_INTERNAL_FUNCTION(png_uint_16,png_gamma_correct,(png_structrp png_ptr,
+   unsigned int value, png_fixed_point gamma_value),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(png_uint_16,png_gamma_16bit_correct,(unsigned int value,
+   png_fixed_point gamma_value),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(png_byte,png_gamma_8bit_correct,(unsigned int value,
+   png_fixed_point gamma_value),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_destroy_gamma_table,(png_structrp png_ptr),
+   PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_build_gamma_table,(png_structrp png_ptr,
+   int bit_depth),PNG_EMPTY);
+#endif
+
+/* SIMPLIFIED READ/WRITE SUPPORT */
+#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
+   defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
+/* The internal structure that png_image::opaque points to. */
+typedef struct png_control
+{
+   png_structp png_ptr;
+   png_infop   info_ptr;
+   png_voidp   error_buf;           /* Always a jmp_buf at present. */
+
+   png_const_bytep memory;          /* Memory buffer. */
+   png_size_t      size;            /* Size of the memory buffer. */
+
+   unsigned int for_write       :1; /* Otherwise it is a read structure */
+   unsigned int owned_file      :1; /* We own the file in io_ptr */
+} png_control;
+
+/* Return the pointer to the jmp_buf from a png_control: necessary because C
+ * does not reveal the type of the elements of jmp_buf.
+ */
+#ifdef __cplusplus
+#  define png_control_jmp_buf(pc) (((jmp_buf*)((pc)->error_buf))[0])
+#else
+#  define png_control_jmp_buf(pc) ((pc)->error_buf)
+#endif
+
+/* Utility to safely execute a piece of libpng code catching and logging any
+ * errors that might occur.  Returns true on success, false on failure (either
+ * of the function or as a result of a png_error.)
+ */
+PNG_INTERNAL_CALLBACK(void,png_safe_error,(png_structp png_ptr,
+   png_const_charp error_message),PNG_NORETURN);
+
+#ifdef PNG_WARNINGS_SUPPORTED
+PNG_INTERNAL_CALLBACK(void,png_safe_warning,(png_structp png_ptr,
+   png_const_charp warning_message),PNG_EMPTY);
+#else
+#  define png_safe_warning 0/*dummy argument*/
+#endif
+
+PNG_INTERNAL_FUNCTION(int,png_safe_execute,(png_imagep image,
+   int (*function)(png_voidp), png_voidp arg),PNG_EMPTY);
+
+/* Utility to log an error; this also cleans up the png_image; the function
+ * always returns 0 (false).
+ */
+PNG_INTERNAL_FUNCTION(int,png_image_error,(png_imagep image,
+   png_const_charp error_message),PNG_EMPTY);
+
+#ifndef PNG_SIMPLIFIED_READ_SUPPORTED
+/* png_image_free is used by the write code but not exported */
+PNG_INTERNAL_FUNCTION(void, png_image_free, (png_imagep image), PNG_EMPTY);
+#endif /* !SIMPLIFIED_READ */
+
+#endif /* SIMPLIFIED READ/WRITE */
+
+/* These are initialization functions for hardware specific PNG filter
+ * optimizations; list these here then select the appropriate one at compile
+ * time using the macro PNG_FILTER_OPTIMIZATIONS.  If the macro is not defined
+ * the generic code is used.
+ */
+#ifdef PNG_FILTER_OPTIMIZATIONS
+PNG_INTERNAL_FUNCTION(void, PNG_FILTER_OPTIMIZATIONS, (png_structp png_ptr,
+   unsigned int bpp), PNG_EMPTY);
+   /* Just declare the optimization that will be used */
+#else
+   /* List *all* the possible optimizations here - this branch is required if
+    * the builder of libpng passes the definition of PNG_FILTER_OPTIMIZATIONS in
+    * CFLAGS in place of CPPFLAGS *and* uses symbol prefixing.
+    */
+PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_neon,
+   (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
 #endif
 
-/* Maintainer: Put new private prototypes here ^ and in libpngpf.3 */
+/* Maintainer: Put new private prototypes here ^ */
 
 #include "pngdebug.h"
 
@@ -1687,4 +1917,5 @@ PNG_EXTERN void png_build_gamma_table PNGARG((png_structp png_ptr,
 }
 #endif
 
+#endif /* PNG_VERSION_INFO_ONLY */
 #endif /* PNGPRIV_H */
diff --git a/src/3rdparty/libpng/pngread.c b/src/3rdparty/libpng/pngread.c
index 1d8c6b3..6764dbe 100644
--- a/src/3rdparty/libpng/pngread.c
+++ b/src/3rdparty/libpng/pngread.c
@@ -1,8 +1,8 @@
 
 /* pngread.c - read a PNG file
  *
- * Last changed in libpng 1.5.10 [March 8, 2012]
- * Copyright (c) 1998-2012 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.17 [March 26, 2015]
+ * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
@@ -15,6 +15,9 @@
  */
 
 #include "pngpriv.h"
+#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) && defined(PNG_STDIO_SUPPORTED)
+#  include <errno.h>
+#endif
 
 #ifdef PNG_READ_SUPPORTED
 
@@ -23,10 +26,12 @@ PNG_FUNCTION(png_structp,PNGAPI
 png_create_read_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
     png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED)
 {
-
-#ifdef PNG_USER_MEM_SUPPORTED
-   return (png_create_read_struct_2(user_png_ver, error_ptr, error_fn,
-       warn_fn, NULL, NULL, NULL));
+#ifndef PNG_USER_MEM_SUPPORTED
+   png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
+      error_fn, warn_fn, NULL, NULL, NULL);
+#else
+   return png_create_read_struct_2(user_png_ver, error_ptr, error_fn,
+       warn_fn, NULL, NULL, NULL);
 }
 
 /* Alternate create PNG structure for reading, and allocate any memory
@@ -37,131 +42,40 @@ png_create_read_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
     png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
     png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
 {
-#endif /* PNG_USER_MEM_SUPPORTED */
-
-#ifdef PNG_SETJMP_SUPPORTED
-   volatile
-#endif
-   png_structp png_ptr;
-   volatile int png_cleanup_needed = 0;
-
-#ifdef PNG_SETJMP_SUPPORTED
-#ifdef USE_FAR_KEYWORD
-   jmp_buf tmp_jmpbuf;
-#endif
-#endif
-
-   png_debug(1, "in png_create_read_struct");
-
-#ifdef PNG_USER_MEM_SUPPORTED
-   png_ptr = (png_structp)png_create_struct_2(PNG_STRUCT_PNG,
-       malloc_fn, mem_ptr);
-#else
-   png_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG);
-#endif
-   if (png_ptr == NULL)
-      return (NULL);
-
-   /* Added at libpng-1.2.6 */
-#ifdef PNG_USER_LIMITS_SUPPORTED
-   png_ptr->user_width_max = PNG_USER_WIDTH_MAX;
-   png_ptr->user_height_max = PNG_USER_HEIGHT_MAX;
-
-   /* Added at libpng-1.2.43 and 1.4.0 */
-   png_ptr->user_chunk_cache_max = PNG_USER_CHUNK_CACHE_MAX;
-
-   /* Added at libpng-1.2.43 and 1.4.1 */
-   png_ptr->user_chunk_malloc_max = PNG_USER_CHUNK_MALLOC_MAX;
-#endif
-
-#ifdef PNG_SETJMP_SUPPORTED
-/* Applications that neglect to set up their own setjmp() and then
- * encounter a png_error() will longjmp here.  Since the jmpbuf is
- * then meaningless we abort instead of returning.
- */
-#ifdef USE_FAR_KEYWORD
-   if (setjmp(tmp_jmpbuf))
-#else
-   if (setjmp(png_jmpbuf(png_ptr))) /* Sets longjmp to match setjmp */
-#endif
-      PNG_ABORT();
-#ifdef USE_FAR_KEYWORD
-   png_memcpy(png_jmpbuf(png_ptr), tmp_jmpbuf, png_sizeof(jmp_buf));
-#endif
-#endif /* PNG_SETJMP_SUPPORTED */
-
-#ifdef PNG_USER_MEM_SUPPORTED
-   png_set_mem_fn(png_ptr, mem_ptr, malloc_fn, free_fn);
-#endif
-
-   png_set_error_fn(png_ptr, error_ptr, error_fn, warn_fn);
-
-   /* Call the general version checker (shared with read and write code): */
-   if (!png_user_version_check(png_ptr, user_png_ver))
-      png_cleanup_needed = 1;
-
-   if (!png_cleanup_needed)
-   {
-   /* Initialize zbuf - compression buffer */
-   png_ptr->zbuf_size = PNG_ZBUF_SIZE;
-   png_ptr->zbuf = (png_bytep)png_malloc_warn(png_ptr, png_ptr->zbuf_size);
-
-   if (png_ptr->zbuf == NULL)
-      png_cleanup_needed = 1;
-   }
-
-   png_ptr->zstream.zalloc = png_zalloc;
-   png_ptr->zstream.zfree = png_zfree;
-   png_ptr->zstream.opaque = (voidpf)png_ptr;
+   png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
+      error_fn, warn_fn, mem_ptr, malloc_fn, free_fn);
+#endif /* USER_MEM */
 
-   if (!png_cleanup_needed)
+   if (png_ptr != NULL)
    {
-      switch (inflateInit(&png_ptr->zstream))
-      {
-         case Z_OK:
-            break; /* Do nothing */
-
-         case Z_MEM_ERROR:
-            png_warning(png_ptr, "zlib memory error");
-            png_cleanup_needed = 1;
-            break;
+      png_ptr->mode = PNG_IS_READ_STRUCT;
 
-         case Z_STREAM_ERROR:
-            png_warning(png_ptr, "zlib stream error");
-            png_cleanup_needed = 1;
-            break;
-
-         case Z_VERSION_ERROR:
-            png_warning(png_ptr, "zlib version error");
-            png_cleanup_needed = 1;
-            break;
+      /* Added in libpng-1.6.0; this can be used to detect a read structure if
+       * required (it will be zero in a write structure.)
+       */
+#     ifdef PNG_SEQUENTIAL_READ_SUPPORTED
+         png_ptr->IDAT_read_size = PNG_IDAT_READ_SIZE;
+#     endif
 
-         default: png_warning(png_ptr, "Unknown zlib error");
-            png_cleanup_needed = 1;
-      }
-   }
+#     ifdef PNG_BENIGN_READ_ERRORS_SUPPORTED
+         png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN;
 
-   if (png_cleanup_needed)
-   {
-      /* Clean up PNG structure and deallocate any memory. */
-      png_free(png_ptr, png_ptr->zbuf);
-      png_ptr->zbuf = NULL;
-#ifdef PNG_USER_MEM_SUPPORTED
-      png_destroy_struct_2((png_voidp)png_ptr,
-          (png_free_ptr)free_fn, (png_voidp)mem_ptr);
-#else
-      png_destroy_struct((png_voidp)png_ptr);
-#endif
-      return (NULL);
+         /* In stable builds only warn if an application error can be completely
+          * handled.
+          */
+#        if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC
+            png_ptr->flags |= PNG_FLAG_APP_WARNINGS_WARN;
+#        endif
+#     endif
+
+      /* TODO: delay this, it can be done in png_init_io (if the app doesn't
+       * do it itself) avoiding setting the default function if it is not
+       * required.
+       */
+      png_set_read_fn(png_ptr, NULL, NULL);
    }
 
-   png_ptr->zstream.next_out = png_ptr->zbuf;
-   png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
-
-   png_set_read_fn(png_ptr, NULL, NULL);
-
-
-   return (png_ptr);
+   return png_ptr;
 }
 
 
@@ -175,8 +89,12 @@ png_create_read_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
  * read if it is determined that this isn't a valid PNG file.
  */
 void PNGAPI
-png_read_info(png_structp png_ptr, png_infop info_ptr)
+png_read_info(png_structrp png_ptr, png_inforp info_ptr)
 {
+#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+   int keep;
+#endif
+
    png_debug(1, "in png_read_info");
 
    if (png_ptr == NULL || info_ptr == NULL)
@@ -190,13 +108,30 @@ png_read_info(png_structp png_ptr, png_infop info_ptr)
       png_uint_32 length = png_read_chunk_header(png_ptr);
       png_uint_32 chunk_name = png_ptr->chunk_name;
 
-      /* This should be a binary subdivision search or a hash for
-       * matching the chunk name rather than a linear search.
+      /* IDAT logic needs to happen here to simplify getting the two flags
+       * right.
        */
       if (chunk_name == png_IDAT)
-         if (png_ptr->mode & PNG_AFTER_IDAT)
-            png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
+      {
+         if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
+            png_chunk_error(png_ptr, "Missing IHDR before IDAT");
+
+         else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
+             (png_ptr->mode & PNG_HAVE_PLTE) == 0)
+            png_chunk_error(png_ptr, "Missing PLTE before IDAT");
+
+         else if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
+            png_chunk_benign_error(png_ptr, "Too many IDATs found");
+
+         png_ptr->mode |= PNG_HAVE_IDAT;
+      }
+
+      else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
+         png_ptr->mode |= PNG_AFTER_IDAT;
 
+      /* This should be a binary subdivision search or a hash for
+       * matching the chunk name rather than a linear search.
+       */
       if (chunk_name == png_IHDR)
          png_handle_IHDR(png_ptr, info_ptr, length);
 
@@ -204,26 +139,16 @@ png_read_info(png_structp png_ptr, png_infop info_ptr)
          png_handle_IEND(png_ptr, info_ptr, length);
 
 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
-      else if (png_chunk_unknown_handling(png_ptr, chunk_name) !=
-         PNG_HANDLE_CHUNK_AS_DEFAULT)
+      else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
       {
-         if (chunk_name == png_IDAT)
-            png_ptr->mode |= PNG_HAVE_IDAT;
-
-         png_handle_unknown(png_ptr, info_ptr, length);
+         png_handle_unknown(png_ptr, info_ptr, length, keep);
 
          if (chunk_name == png_PLTE)
             png_ptr->mode |= PNG_HAVE_PLTE;
 
          else if (chunk_name == png_IDAT)
          {
-            if (!(png_ptr->mode & PNG_HAVE_IHDR))
-               png_error(png_ptr, "Missing IHDR before IDAT");
-
-            else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
-                !(png_ptr->mode & PNG_HAVE_PLTE))
-               png_error(png_ptr, "Missing PLTE before IDAT");
-
+            png_ptr->idat_size = 0; /* It has been consumed */
             break;
          }
       }
@@ -233,15 +158,7 @@ png_read_info(png_structp png_ptr, png_infop info_ptr)
 
       else if (chunk_name == png_IDAT)
       {
-         if (!(png_ptr->mode & PNG_HAVE_IHDR))
-            png_error(png_ptr, "Missing IHDR before IDAT");
-
-         else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
-             !(png_ptr->mode & PNG_HAVE_PLTE))
-            png_error(png_ptr, "Missing PLTE before IDAT");
-
          png_ptr->idat_size = length;
-         png_ptr->mode |= PNG_HAVE_IDAT;
          break;
       }
 
@@ -331,27 +248,36 @@ png_read_info(png_structp png_ptr, png_infop info_ptr)
 #endif
 
       else
-         png_handle_unknown(png_ptr, info_ptr, length);
+         png_handle_unknown(png_ptr, info_ptr, length,
+            PNG_HANDLE_CHUNK_AS_DEFAULT);
    }
 }
-#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
+#endif /* SEQUENTIAL_READ */
 
 /* Optional call to update the users info_ptr structure */
 void PNGAPI
-png_read_update_info(png_structp png_ptr, png_infop info_ptr)
+png_read_update_info(png_structrp png_ptr, png_inforp info_ptr)
 {
    png_debug(1, "in png_read_update_info");
 
-   if (png_ptr == NULL)
-      return;
+   if (png_ptr != NULL)
+   {
+      if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
+      {
+         png_read_start_row(png_ptr);
 
-   png_read_start_row(png_ptr);
+#        ifdef PNG_READ_TRANSFORMS_SUPPORTED
+            png_read_transform_info(png_ptr, info_ptr);
+#        else
+            PNG_UNUSED(info_ptr)
+#        endif
+      }
 
-#ifdef PNG_READ_TRANSFORMS_SUPPORTED
-   png_read_transform_info(png_ptr, info_ptr);
-#else
-   PNG_UNUSED(info_ptr)
-#endif
+      /* New in 1.6.0 this avoids the bug of doing the initializations twice */
+      else
+         png_app_error(png_ptr,
+            "png_read_update_info/png_start_read_image: duplicate call");
+   }
 }
 
 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
@@ -361,21 +287,93 @@ png_read_update_info(png_structp png_ptr, png_infop info_ptr)
  * If the user doesn't call this, we will do it ourselves.
  */
 void PNGAPI
-png_start_read_image(png_structp png_ptr)
+png_start_read_image(png_structrp png_ptr)
 {
    png_debug(1, "in png_start_read_image");
 
    if (png_ptr != NULL)
-     png_read_start_row(png_ptr);
+   {
+      if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
+         png_read_start_row(png_ptr);
+
+      /* New in 1.6.0 this avoids the bug of doing the initializations twice */
+      else
+         png_app_error(png_ptr,
+            "png_start_read_image/png_read_update_info: duplicate call");
+   }
 }
-#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
+#endif /* SEQUENTIAL_READ */
 
 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
-void PNGAPI
-png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
+#ifdef PNG_MNG_FEATURES_SUPPORTED
+/* Undoes intrapixel differencing,
+ * NOTE: this is apparently only supported in the 'sequential' reader.
+ */
+static void
+png_do_read_intrapixel(png_row_infop row_info, png_bytep row)
 {
-   int ret;
+   png_debug(1, "in png_do_read_intrapixel");
+
+   if (
+       (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
+   {
+      int bytes_per_pixel;
+      png_uint_32 row_width = row_info->width;
+
+      if (row_info->bit_depth == 8)
+      {
+         png_bytep rp;
+         png_uint_32 i;
+
+         if (row_info->color_type == PNG_COLOR_TYPE_RGB)
+            bytes_per_pixel = 3;
+
+         else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+            bytes_per_pixel = 4;
+
+         else
+            return;
+
+         for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
+         {
+            *(rp) = (png_byte)((256 + *rp + *(rp + 1)) & 0xff);
+            *(rp+2) = (png_byte)((256 + *(rp + 2) + *(rp + 1)) & 0xff);
+         }
+      }
+      else if (row_info->bit_depth == 16)
+      {
+         png_bytep rp;
+         png_uint_32 i;
+
+         if (row_info->color_type == PNG_COLOR_TYPE_RGB)
+            bytes_per_pixel = 6;
 
+         else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+            bytes_per_pixel = 8;
+
+         else
+            return;
+
+         for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
+         {
+            png_uint_32 s0   = (*(rp    ) << 8) | *(rp + 1);
+            png_uint_32 s1   = (*(rp + 2) << 8) | *(rp + 3);
+            png_uint_32 s2   = (*(rp + 4) << 8) | *(rp + 5);
+            png_uint_32 red  = (s0 + s1 + 65536) & 0xffff;
+            png_uint_32 blue = (s2 + s1 + 65536) & 0xffff;
+            *(rp    ) = (png_byte)((red >> 8) & 0xff);
+            *(rp + 1) = (png_byte)(red & 0xff);
+            *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
+            *(rp + 5) = (png_byte)(blue & 0xff);
+         }
+      }
+   }
+}
+#endif /* MNG_FEATURES */
+
+void PNGAPI
+png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row)
+{
    png_row_info row_info;
 
    if (png_ptr == NULL)
@@ -387,7 +385,7 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
    /* png_read_start_row sets the information (in particular iwidth) for this
     * interlace pass.
     */
-   if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
+   if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
       png_read_start_row(png_ptr);
 
    /* 1.5.6: row_info moved out of png_struct to a local here. */
@@ -398,45 +396,47 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
    row_info.pixel_depth = png_ptr->pixel_depth;
    row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
 
+#ifdef PNG_WARNINGS_SUPPORTED
    if (png_ptr->row_number == 0 && png_ptr->pass == 0)
    {
    /* Check for transforms that have been set but were defined out */
 #if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED)
-   if (png_ptr->transformations & PNG_INVERT_MONO)
+   if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
       png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined");
 #endif
 
 #if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED)
-   if (png_ptr->transformations & PNG_FILLER)
+   if ((png_ptr->transformations & PNG_FILLER) != 0)
       png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined");
 #endif
 
 #if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
     !defined(PNG_READ_PACKSWAP_SUPPORTED)
-   if (png_ptr->transformations & PNG_PACKSWAP)
+   if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
       png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined");
 #endif
 
 #if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED)
-   if (png_ptr->transformations & PNG_PACK)
+   if ((png_ptr->transformations & PNG_PACK) != 0)
       png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined");
 #endif
 
 #if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED)
-   if (png_ptr->transformations & PNG_SHIFT)
+   if ((png_ptr->transformations & PNG_SHIFT) != 0)
       png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined");
 #endif
 
 #if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED)
-   if (png_ptr->transformations & PNG_BGR)
+   if ((png_ptr->transformations & PNG_BGR) != 0)
       png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined");
 #endif
 
 #if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED)
-   if (png_ptr->transformations & PNG_SWAP_BYTES)
+   if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
       png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined");
 #endif
    }
+#endif /* WARNINGS */
 
 #ifdef PNG_READ_INTERLACING_SUPPORTED
    /* If interlaced and we do not need a new row, combine row and return.
@@ -445,7 +445,8 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
     * untransformed) and, because of the libpng API for interlaced images, this
     * means we must transform before de-interlacing.
     */
-   if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
+   if (png_ptr->interlaced != 0 &&
+       (png_ptr->transformations & PNG_INTERLACE) != 0)
    {
       switch (png_ptr->pass)
       {
@@ -502,6 +503,7 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
                return;
             }
             break;
+
          case 5:
             if ((png_ptr->row_number & 1) || png_ptr->width < 2)
             {
@@ -515,7 +517,7 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
 
          default:
          case 6:
-            if (!(png_ptr->row_number & 1))
+            if ((png_ptr->row_number & 1) == 0)
             {
                png_read_finish_row(png_ptr);
                return;
@@ -525,52 +527,11 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
    }
 #endif
 
-   if (!(png_ptr->mode & PNG_HAVE_IDAT))
+   if ((png_ptr->mode & PNG_HAVE_IDAT) == 0)
       png_error(png_ptr, "Invalid attempt to read row data");
 
-   png_ptr->zstream.next_out = png_ptr->row_buf;
-   png_ptr->zstream.avail_out =
-       (uInt)(PNG_ROWBYTES(png_ptr->pixel_depth,
-       png_ptr->iwidth) + 1);
-
-   do
-   {
-      if (!(png_ptr->zstream.avail_in))
-      {
-         while (!png_ptr->idat_size)
-         {
-            png_crc_finish(png_ptr, 0);
-
-            png_ptr->idat_size = png_read_chunk_header(png_ptr);
-            if (png_ptr->chunk_name != png_IDAT)
-               png_error(png_ptr, "Not enough image data");
-         }
-         png_ptr->zstream.avail_in = (uInt)png_ptr->zbuf_size;
-         png_ptr->zstream.next_in = png_ptr->zbuf;
-         if (png_ptr->zbuf_size > png_ptr->idat_size)
-            png_ptr->zstream.avail_in = (uInt)png_ptr->idat_size;
-         png_crc_read(png_ptr, png_ptr->zbuf,
-             (png_size_t)png_ptr->zstream.avail_in);
-         png_ptr->idat_size -= png_ptr->zstream.avail_in;
-      }
-
-      ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
-
-      if (ret == Z_STREAM_END)
-      {
-         if (png_ptr->zstream.avail_out || png_ptr->zstream.avail_in ||
-            png_ptr->idat_size)
-            png_benign_error(png_ptr, "Extra compressed data");
-         png_ptr->mode |= PNG_AFTER_IDAT;
-         png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
-         break;
-      }
-
-      if (ret != Z_OK)
-         png_error(png_ptr, png_ptr->zstream.msg ? png_ptr->zstream.msg :
-             "Decompression error");
-
-   } while (png_ptr->zstream.avail_out);
+   /* Fill the row with IDAT data: */
+   png_read_IDAT_data(png_ptr, png_ptr->row_buf, row_info.rowbytes + 1);
 
    if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
    {
@@ -586,10 +547,10 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
     * it may not be in the future, so this was changed just to copy the
     * interlaced count:
     */
-   png_memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
+   memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
 
 #ifdef PNG_MNG_FEATURES_SUPPORTED
-   if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
+   if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
        (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
    {
       /* Intrapixel differencing */
@@ -597,7 +558,6 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
    }
 #endif
 
-
 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
    if (png_ptr->transformations)
       png_do_read_transformations(png_ptr, &row_info);
@@ -615,9 +575,9 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
       png_error(png_ptr, "internal sequential row size calculation error");
 
 #ifdef PNG_READ_INTERLACING_SUPPORTED
-   /* Blow up interlaced rows to full size */
-   if (png_ptr->interlaced &&
-      (png_ptr->transformations & PNG_INTERLACE))
+   /* Expand interlaced rows to full size */
+   if (png_ptr->interlaced != 0 &&
+      (png_ptr->transformations & PNG_INTERLACE) != 0)
    {
       if (png_ptr->pass < 6)
          png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
@@ -643,8 +603,9 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
 
    if (png_ptr->read_row_fn != NULL)
       (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
+
 }
-#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
+#endif /* SEQUENTIAL_READ */
 
 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 /* Read one or more rows of image data.  If the image is interlaced,
@@ -672,7 +633,7 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
  */
 
 void PNGAPI
-png_read_rows(png_structp png_ptr, png_bytepp row,
+png_read_rows(png_structrp png_ptr, png_bytepp row,
     png_bytepp display_row, png_uint_32 num_rows)
 {
    png_uint_32 i;
@@ -711,7 +672,7 @@ png_read_rows(png_structp png_ptr, png_bytepp row,
          dp++;
       }
 }
-#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
+#endif /* SEQUENTIAL_READ */
 
 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 /* Read the entire image.  If the image has an alpha channel or a tRNS
@@ -727,7 +688,7 @@ png_read_rows(png_structp png_ptr, png_bytepp row,
  * [*] png_handle_alpha() does not exist yet, as of this version of libpng
  */
 void PNGAPI
-png_read_image(png_structp png_ptr, png_bytepp image)
+png_read_image(png_structrp png_ptr, png_bytepp image)
 {
    png_uint_32 i, image_height;
    int pass, j;
@@ -739,7 +700,7 @@ png_read_image(png_structp png_ptr, png_bytepp image)
       return;
 
 #ifdef PNG_READ_INTERLACING_SUPPORTED
-   if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
+   if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
    {
       pass = png_set_interlace_handling(png_ptr);
       /* And make sure transforms are initialized. */
@@ -747,7 +708,8 @@ png_read_image(png_structp png_ptr, png_bytepp image)
    }
    else
    {
-      if (png_ptr->interlaced && !(png_ptr->transformations & PNG_INTERLACE))
+      if (png_ptr->interlaced != 0 &&
+          (png_ptr->transformations & PNG_INTERLACE) == 0)
       {
          /* Caller called png_start_read_image or png_read_update_info without
           * first turning on the PNG_INTERLACE transform.  We can fix this here,
@@ -784,7 +746,7 @@ png_read_image(png_structp png_ptr, png_bytepp image)
       }
    }
 }
-#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
+#endif /* SEQUENTIAL_READ */
 
 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 /* Read the end of the PNG file.  Will not read past the end of the
@@ -792,14 +754,24 @@ png_read_image(png_structp png_ptr, png_bytepp image)
  * or time information at the end of the file, if info is not NULL.
  */
 void PNGAPI
-png_read_end(png_structp png_ptr, png_infop info_ptr)
+png_read_end(png_structrp png_ptr, png_inforp info_ptr)
 {
+#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+   int keep;
+#endif
+
    png_debug(1, "in png_read_end");
 
    if (png_ptr == NULL)
       return;
 
-   png_crc_finish(png_ptr, 0); /* Finish off CRC from last IDAT chunk */
+   /* If png_read_end is called in the middle of reading the rows there may
+    * still be pending IDAT data and an owned zstream.  Deal with this here.
+    */
+#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+   if (png_chunk_unknown_handling(png_ptr, png_IDAT) == 0)
+#endif
+      png_read_finish_IDAT(png_ptr);
 
 #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
    /* Report invalid palette index; added at libng-1.5.10 */
@@ -813,22 +785,25 @@ png_read_end(png_structp png_ptr, png_infop info_ptr)
       png_uint_32 length = png_read_chunk_header(png_ptr);
       png_uint_32 chunk_name = png_ptr->chunk_name;
 
-      if (chunk_name == png_IHDR)
+      if (chunk_name == png_IEND)
+         png_handle_IEND(png_ptr, info_ptr, length);
+
+      else if (chunk_name == png_IHDR)
          png_handle_IHDR(png_ptr, info_ptr, length);
 
-      else if (chunk_name == png_IEND)
-         png_handle_IEND(png_ptr, info_ptr, length);
+      else if (info_ptr == NULL)
+         png_crc_finish(png_ptr, length);
 
 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
-      else if (png_chunk_unknown_handling(png_ptr, chunk_name) !=
-         PNG_HANDLE_CHUNK_AS_DEFAULT)
+      else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
       {
          if (chunk_name == png_IDAT)
          {
-            if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
+            if ((length > 0) ||
+                (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
                png_benign_error(png_ptr, "Too many IDATs found");
          }
-         png_handle_unknown(png_ptr, info_ptr, length);
+         png_handle_unknown(png_ptr, info_ptr, length, keep);
          if (chunk_name == png_PLTE)
             png_ptr->mode |= PNG_HAVE_PLTE;
       }
@@ -839,7 +814,7 @@ png_read_end(png_structp png_ptr, png_infop info_ptr)
          /* Zero length IDATs are legal after the last IDAT has been
           * read, but not after other chunks have been read.
           */
-         if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
+         if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
             png_benign_error(png_ptr, "Too many IDATs found");
 
          png_crc_finish(png_ptr, length);
@@ -933,181 +908,106 @@ png_read_end(png_structp png_ptr, png_infop info_ptr)
 #endif
 
       else
-         png_handle_unknown(png_ptr, info_ptr, length);
-   } while (!(png_ptr->mode & PNG_HAVE_IEND));
-}
-#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
-
-/* Free all memory used by the read */
-void PNGAPI
-png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
-    png_infopp end_info_ptr_ptr)
-{
-   png_structp png_ptr = NULL;
-   png_infop info_ptr = NULL, end_info_ptr = NULL;
-#ifdef PNG_USER_MEM_SUPPORTED
-   png_free_ptr free_fn = NULL;
-   png_voidp mem_ptr = NULL;
-#endif
-
-   png_debug(1, "in png_destroy_read_struct");
-
-   if (png_ptr_ptr != NULL)
-      png_ptr = *png_ptr_ptr;
-   if (png_ptr == NULL)
-      return;
-
-#ifdef PNG_USER_MEM_SUPPORTED
-   free_fn = png_ptr->free_fn;
-   mem_ptr = png_ptr->mem_ptr;
-#endif
-
-   if (info_ptr_ptr != NULL)
-      info_ptr = *info_ptr_ptr;
-
-   if (end_info_ptr_ptr != NULL)
-      end_info_ptr = *end_info_ptr_ptr;
-
-   png_read_destroy(png_ptr, info_ptr, end_info_ptr);
-
-   if (info_ptr != NULL)
-   {
-#ifdef PNG_TEXT_SUPPORTED
-      png_free_data(png_ptr, info_ptr, PNG_FREE_TEXT, -1);
-#endif
-
-#ifdef PNG_USER_MEM_SUPPORTED
-      png_destroy_struct_2((png_voidp)info_ptr, (png_free_ptr)free_fn,
-          (png_voidp)mem_ptr);
-#else
-      png_destroy_struct((png_voidp)info_ptr);
-#endif
-      *info_ptr_ptr = NULL;
-   }
-
-   if (end_info_ptr != NULL)
-   {
-#ifdef PNG_READ_TEXT_SUPPORTED
-      png_free_data(png_ptr, end_info_ptr, PNG_FREE_TEXT, -1);
-#endif
-#ifdef PNG_USER_MEM_SUPPORTED
-      png_destroy_struct_2((png_voidp)end_info_ptr, (png_free_ptr)free_fn,
-          (png_voidp)mem_ptr);
-#else
-      png_destroy_struct((png_voidp)end_info_ptr);
-#endif
-      *end_info_ptr_ptr = NULL;
-   }
-
-   if (png_ptr != NULL)
-   {
-#ifdef PNG_USER_MEM_SUPPORTED
-      png_destroy_struct_2((png_voidp)png_ptr, (png_free_ptr)free_fn,
-          (png_voidp)mem_ptr);
-#else
-      png_destroy_struct((png_voidp)png_ptr);
-#endif
-      *png_ptr_ptr = NULL;
-   }
+         png_handle_unknown(png_ptr, info_ptr, length,
+            PNG_HANDLE_CHUNK_AS_DEFAULT);
+   } while ((png_ptr->mode & PNG_HAVE_IEND) == 0);
 }
+#endif /* SEQUENTIAL_READ */
 
-/* Free all memory used by the read (old method) */
-void /* PRIVATE */
-png_read_destroy(png_structp png_ptr, png_infop info_ptr,
-    png_infop end_info_ptr)
+/* Free all memory used in the read struct */
+static void
+png_read_destroy(png_structrp png_ptr)
 {
-#ifdef PNG_SETJMP_SUPPORTED
-   jmp_buf tmp_jmp;
-#endif
-   png_error_ptr error_fn;
-#ifdef PNG_WARNINGS_SUPPORTED
-   png_error_ptr warning_fn;
-#endif
-   png_voidp error_ptr;
-#ifdef PNG_USER_MEM_SUPPORTED
-   png_free_ptr free_fn;
-#endif
-
    png_debug(1, "in png_read_destroy");
 
-   if (info_ptr != NULL)
-      png_info_destroy(png_ptr, info_ptr);
-
-   if (end_info_ptr != NULL)
-      png_info_destroy(png_ptr, end_info_ptr);
-
 #ifdef PNG_READ_GAMMA_SUPPORTED
    png_destroy_gamma_table(png_ptr);
 #endif
 
-   png_free(png_ptr, png_ptr->zbuf);
    png_free(png_ptr, png_ptr->big_row_buf);
+   png_ptr->big_row_buf = NULL;
    png_free(png_ptr, png_ptr->big_prev_row);
-   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->big_prev_row = NULL;
+   png_free(png_ptr, png_ptr->read_buffer);
+   png_ptr->read_buffer = NULL;
 
 #ifdef PNG_READ_QUANTIZE_SUPPORTED
    png_free(png_ptr, png_ptr->palette_lookup);
+   png_ptr->palette_lookup = NULL;
    png_free(png_ptr, png_ptr->quantize_index);
+   png_ptr->quantize_index = NULL;
 #endif
 
-   if (png_ptr->free_me & PNG_FREE_PLTE)
+   if ((png_ptr->free_me & PNG_FREE_PLTE) != 0)
+   {
       png_zfree(png_ptr, png_ptr->palette);
+      png_ptr->palette = NULL;
+   }
    png_ptr->free_me &= ~PNG_FREE_PLTE;
 
 #if defined(PNG_tRNS_SUPPORTED) || \
     defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
-   if (png_ptr->free_me & PNG_FREE_TRNS)
+   if ((png_ptr->free_me & PNG_FREE_TRNS) != 0)
+   {
       png_free(png_ptr, png_ptr->trans_alpha);
+      png_ptr->trans_alpha = NULL;
+   }
    png_ptr->free_me &= ~PNG_FREE_TRNS;
 #endif
 
-#ifdef PNG_READ_hIST_SUPPORTED
-   if (png_ptr->free_me & PNG_FREE_HIST)
-      png_free(png_ptr, png_ptr->hist);
-   png_ptr->free_me &= ~PNG_FREE_HIST;
-#endif
-
    inflateEnd(&png_ptr->zstream);
 
 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
    png_free(png_ptr, png_ptr->save_buffer);
+   png_ptr->save_buffer = NULL;
 #endif
 
-   /* Save the important info out of the png_struct, in case it is
-    * being used again.
-    */
-#ifdef PNG_SETJMP_SUPPORTED
-   png_memcpy(tmp_jmp, png_ptr->longjmp_buffer, png_sizeof(jmp_buf));
+#if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) && \
+   defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
+   png_free(png_ptr, png_ptr->unknown_chunk.data);
+   png_ptr->unknown_chunk.data = NULL;
 #endif
 
-   error_fn = png_ptr->error_fn;
-#ifdef PNG_WARNINGS_SUPPORTED
-   warning_fn = png_ptr->warning_fn;
-#endif
-   error_ptr = png_ptr->error_ptr;
-#ifdef PNG_USER_MEM_SUPPORTED
-   free_fn = png_ptr->free_fn;
+#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
+   png_free(png_ptr, png_ptr->chunk_list);
+   png_ptr->chunk_list = NULL;
 #endif
 
-   png_memset(png_ptr, 0, png_sizeof(png_struct));
+   /* NOTE: the 'setjmp' buffer may still be allocated and the memory and error
+    * callbacks are still set at this point.  They are required to complete the
+    * destruction of the png_struct itself.
+    */
+}
 
-   png_ptr->error_fn = error_fn;
-#ifdef PNG_WARNINGS_SUPPORTED
-   png_ptr->warning_fn = warning_fn;
-#endif
-   png_ptr->error_ptr = error_ptr;
-#ifdef PNG_USER_MEM_SUPPORTED
-   png_ptr->free_fn = free_fn;
-#endif
+/* Free all memory used by the read */
+void PNGAPI
+png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
+    png_infopp end_info_ptr_ptr)
+{
+   png_structrp png_ptr = NULL;
 
-#ifdef PNG_SETJMP_SUPPORTED
-   png_memcpy(png_ptr->longjmp_buffer, tmp_jmp, png_sizeof(jmp_buf));
-#endif
+   png_debug(1, "in png_destroy_read_struct");
+
+   if (png_ptr_ptr != NULL)
+      png_ptr = *png_ptr_ptr;
+
+   if (png_ptr == NULL)
+      return;
 
+   /* libpng 1.6.0: use the API to destroy info structs to ensure consistent
+    * behavior.  Prior to 1.6.0 libpng did extra 'info' destruction in this API.
+    * The extra was, apparently, unnecessary yet this hides memory leak bugs.
+    */
+   png_destroy_info_struct(png_ptr, end_info_ptr_ptr);
+   png_destroy_info_struct(png_ptr, info_ptr_ptr);
+
+   *png_ptr_ptr = NULL;
+   png_read_destroy(png_ptr);
+   png_destroy_png_struct(png_ptr);
 }
 
 void PNGAPI
-png_set_read_status_fn(png_structp png_ptr, png_read_status_ptr read_row_fn)
+png_set_read_status_fn(png_structrp png_ptr, png_read_status_ptr read_row_fn)
 {
    if (png_ptr == NULL)
       return;
@@ -1119,12 +1019,10 @@ png_set_read_status_fn(png_structp png_ptr, png_read_status_ptr read_row_fn)
 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 #ifdef PNG_INFO_IMAGE_SUPPORTED
 void PNGAPI
-png_read_png(png_structp png_ptr, png_infop info_ptr,
+png_read_png(png_structrp png_ptr, png_inforp info_ptr,
                            int transforms,
                            voidp params)
 {
-   int row;
-
    if (png_ptr == NULL || info_ptr == NULL)
       return;
 
@@ -1132,130 +1030,153 @@ png_read_png(png_structp png_ptr, png_infop info_ptr,
     * PNG file before the first IDAT (image data chunk).
     */
    png_read_info(png_ptr, info_ptr);
-   if (info_ptr->height > PNG_UINT_32_MAX/png_sizeof(png_bytep))
+   if (info_ptr->height > PNG_UINT_32_MAX/(sizeof (png_bytep)))
       png_error(png_ptr, "Image is too high to process with png_read_png()");
 
    /* -------------- image transformations start here ------------------- */
+   /* libpng 1.6.10: add code to cause a png_app_error if a selected TRANSFORM
+    * is not implemented.  This will only happen in de-configured (non-default)
+    * libpng builds.  The results can be unexpected - png_read_png may return
+    * short or mal-formed rows because the transform is skipped.
+    */
 
-#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
    /* Tell libpng to strip 16-bit/color files down to 8 bits per color.
     */
-   if (transforms & PNG_TRANSFORM_SCALE_16)
-   {
+   if ((transforms & PNG_TRANSFORM_SCALE_16) != 0)
      /* Added at libpng-1.5.4. "strip_16" produces the same result that it
       * did in earlier versions, while "scale_16" is now more accurate.
       */
+#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
       png_set_scale_16(png_ptr);
-   }
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_SCALE_16 not supported");
 #endif
 
-#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
    /* If both SCALE and STRIP are required pngrtran will effectively cancel the
     * latter by doing SCALE first.  This is ok and allows apps not to check for
     * which is supported to get the right answer.
     */
-   if (transforms & PNG_TRANSFORM_STRIP_16)
+   if ((transforms & PNG_TRANSFORM_STRIP_16) != 0)
+#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
       png_set_strip_16(png_ptr);
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_16 not supported");
 #endif
 
-#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
    /* Strip alpha bytes from the input data without combining with
     * the background (not recommended).
     */
-   if (transforms & PNG_TRANSFORM_STRIP_ALPHA)
+   if ((transforms & PNG_TRANSFORM_STRIP_ALPHA) != 0)
+#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
       png_set_strip_alpha(png_ptr);
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_ALPHA not supported");
 #endif
 
-#if defined(PNG_READ_PACK_SUPPORTED) && !defined(PNG_READ_EXPAND_SUPPORTED)
    /* Extract multiple pixels with bit depths of 1, 2, or 4 from a single
     * byte into separate bytes (useful for paletted and grayscale images).
     */
-   if (transforms & PNG_TRANSFORM_PACKING)
+   if ((transforms & PNG_TRANSFORM_PACKING) != 0)
+#ifdef PNG_READ_PACK_SUPPORTED
       png_set_packing(png_ptr);
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported");
 #endif
 
-#ifdef PNG_READ_PACKSWAP_SUPPORTED
    /* Change the order of packed pixels to least significant bit first
     * (not useful if you are using png_set_packing).
     */
-   if (transforms & PNG_TRANSFORM_PACKSWAP)
+   if ((transforms & PNG_TRANSFORM_PACKSWAP) != 0)
+#ifdef PNG_READ_PACKSWAP_SUPPORTED
       png_set_packswap(png_ptr);
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported");
 #endif
 
-#ifdef PNG_READ_EXPAND_SUPPORTED
    /* Expand paletted colors into true RGB triplets
     * Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel
     * Expand paletted or RGB images with transparency to full alpha
     * channels so the data will be available as RGBA quartets.
     */
-   if (transforms & PNG_TRANSFORM_EXPAND)
-      if ((png_ptr->bit_depth < 8) ||
-          (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ||
-          (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)))
-         png_set_expand(png_ptr);
+   if ((transforms & PNG_TRANSFORM_EXPAND) != 0)
+#ifdef PNG_READ_EXPAND_SUPPORTED
+      png_set_expand(png_ptr);
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND not supported");
 #endif
 
    /* We don't handle background color or gamma transformation or quantizing.
     */
 
-#ifdef PNG_READ_INVERT_SUPPORTED
    /* Invert monochrome files to have 0 as white and 1 as black
     */
-   if (transforms & PNG_TRANSFORM_INVERT_MONO)
+   if ((transforms & PNG_TRANSFORM_INVERT_MONO) != 0)
+#ifdef PNG_READ_INVERT_SUPPORTED
       png_set_invert_mono(png_ptr);
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported");
 #endif
 
-#ifdef PNG_READ_SHIFT_SUPPORTED
    /* If you want to shift the pixel values from the range [0,255] or
     * [0,65535] to the original [0,7] or [0,31], or whatever range the
     * colors were originally in:
     */
-   if ((transforms & PNG_TRANSFORM_SHIFT)
-       && png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT))
-   {
-      png_color_8p sig_bit;
-
-      png_get_sBIT(png_ptr, info_ptr, &sig_bit);
-      png_set_shift(png_ptr, sig_bit);
-   }
+   if ((transforms & PNG_TRANSFORM_SHIFT) != 0)
+#ifdef PNG_READ_SHIFT_SUPPORTED
+      if ((info_ptr->valid & PNG_INFO_sBIT) != 0)
+         png_set_shift(png_ptr, &info_ptr->sig_bit);
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported");
 #endif
 
-#ifdef PNG_READ_BGR_SUPPORTED
    /* Flip the RGB pixels to BGR (or RGBA to BGRA) */
-   if (transforms & PNG_TRANSFORM_BGR)
+   if ((transforms & PNG_TRANSFORM_BGR) != 0)
+#ifdef PNG_READ_BGR_SUPPORTED
       png_set_bgr(png_ptr);
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported");
 #endif
 
-#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
    /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
-   if (transforms & PNG_TRANSFORM_SWAP_ALPHA)
+   if ((transforms & PNG_TRANSFORM_SWAP_ALPHA) != 0)
+#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
       png_set_swap_alpha(png_ptr);
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported");
 #endif
 
-#ifdef PNG_READ_SWAP_SUPPORTED
    /* Swap bytes of 16-bit files to least significant byte first */
-   if (transforms & PNG_TRANSFORM_SWAP_ENDIAN)
+   if ((transforms & PNG_TRANSFORM_SWAP_ENDIAN) != 0)
+#ifdef PNG_READ_SWAP_SUPPORTED
       png_set_swap(png_ptr);
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported");
 #endif
 
 /* Added at libpng-1.2.41 */
-#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
    /* Invert the alpha channel from opacity to transparency */
-   if (transforms & PNG_TRANSFORM_INVERT_ALPHA)
+   if ((transforms & PNG_TRANSFORM_INVERT_ALPHA) != 0)
+#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
       png_set_invert_alpha(png_ptr);
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported");
 #endif
 
 /* Added at libpng-1.2.41 */
-#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
    /* Expand grayscale image to RGB */
-   if (transforms & PNG_TRANSFORM_GRAY_TO_RGB)
+   if ((transforms & PNG_TRANSFORM_GRAY_TO_RGB) != 0)
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
       png_set_gray_to_rgb(png_ptr);
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_GRAY_TO_RGB not supported");
 #endif
 
 /* Added at libpng-1.5.4 */
+   if ((transforms & PNG_TRANSFORM_EXPAND_16) != 0)
 #ifdef PNG_READ_EXPAND_16_SUPPORTED
-   if (transforms & PNG_TRANSFORM_EXPAND_16)
       png_set_expand_16(png_ptr);
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND_16 not supported");
 #endif
 
    /* We don't handle adding filler bytes */
@@ -1278,16 +1199,17 @@ png_read_png(png_structp png_ptr, png_infop info_ptr,
    {
       png_uint_32 iptr;
 
-      info_ptr->row_pointers = (png_bytepp)png_malloc(png_ptr,
-          info_ptr->height * png_sizeof(png_bytep));
+      info_ptr->row_pointers = png_voidcast(png_bytepp, png_malloc(png_ptr,
+          info_ptr->height * (sizeof (png_bytep))));
+
       for (iptr=0; iptr<info_ptr->height; iptr++)
          info_ptr->row_pointers[iptr] = NULL;
 
       info_ptr->free_me |= PNG_FREE_ROWS;
 
-      for (row = 0; row < (int)info_ptr->height; row++)
-         info_ptr->row_pointers[row] = (png_bytep)png_malloc(png_ptr,
-            png_get_rowbytes(png_ptr, info_ptr));
+      for (iptr = 0; iptr < info_ptr->height; iptr++)
+         info_ptr->row_pointers[iptr] = png_voidcast(png_bytep,
+            png_malloc(png_ptr, info_ptr->rowbytes));
    }
 
    png_read_image(png_ptr, info_ptr->row_pointers);
@@ -1296,10 +1218,2917 @@ png_read_png(png_structp png_ptr, png_infop info_ptr,
    /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
    png_read_end(png_ptr, info_ptr);
 
-   PNG_UNUSED(transforms)   /* Quiet compiler warnings */
    PNG_UNUSED(params)
+}
+#endif /* INFO_IMAGE */
+#endif /* SEQUENTIAL_READ */
+
+#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
+/* SIMPLIFIED READ
+ *
+ * This code currently relies on the sequential reader, though it could easily
+ * be made to work with the progressive one.
+ */
+/* Arguments to png_image_finish_read: */
+
+/* Encoding of PNG data (used by the color-map code) */
+#  define P_NOTSET  0 /* File encoding not yet known */
+#  define P_sRGB    1 /* 8-bit encoded to sRGB gamma */
+#  define P_LINEAR  2 /* 16-bit linear: not encoded, NOT pre-multiplied! */
+#  define P_FILE    3 /* 8-bit encoded to file gamma, not sRGB or linear */
+#  define P_LINEAR8 4 /* 8-bit linear: only from a file value */
+
+/* Color-map processing: after libpng has run on the PNG image further
+ * processing may be needed to convert the data to color-map indices.
+ */
+#define PNG_CMAP_NONE      0
+#define PNG_CMAP_GA        1 /* Process GA data to a color-map with alpha */
+#define PNG_CMAP_TRANS     2 /* Process GA data to a background index */
+#define PNG_CMAP_RGB       3 /* Process RGB data */
+#define PNG_CMAP_RGB_ALPHA 4 /* Process RGBA data */
+
+/* The following document where the background is for each processing case. */
+#define PNG_CMAP_NONE_BACKGROUND      256
+#define PNG_CMAP_GA_BACKGROUND        231
+#define PNG_CMAP_TRANS_BACKGROUND     254
+#define PNG_CMAP_RGB_BACKGROUND       256
+#define PNG_CMAP_RGB_ALPHA_BACKGROUND 216
+
+typedef struct
+{
+   /* Arguments: */
+   png_imagep image;
+   png_voidp  buffer;
+   png_int_32 row_stride;
+   png_voidp  colormap;
+   png_const_colorp background;
+   /* Local variables: */
+   png_voidp       local_row;
+   png_voidp       first_row;
+   ptrdiff_t       row_bytes;           /* step between rows */
+   int             file_encoding;       /* E_ values above */
+   png_fixed_point gamma_to_linear;     /* For P_FILE, reciprocal of gamma */
+   int             colormap_processing; /* PNG_CMAP_ values above */
+} png_image_read_control;
+
+/* Do all the *safe* initialization - 'safe' means that png_error won't be
+ * called, so setting up the jmp_buf is not required.  This means that anything
+ * called from here must *not* call png_malloc - it has to call png_malloc_warn
+ * instead so that control is returned safely back to this routine.
+ */
+static int
+png_image_read_init(png_imagep image)
+{
+   if (image->opaque == NULL)
+   {
+      png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, image,
+          png_safe_error, png_safe_warning);
+
+      /* And set the rest of the structure to NULL to ensure that the various
+       * fields are consistent.
+       */
+      memset(image, 0, (sizeof *image));
+      image->version = PNG_IMAGE_VERSION;
+
+      if (png_ptr != NULL)
+      {
+         png_infop info_ptr = png_create_info_struct(png_ptr);
+
+         if (info_ptr != NULL)
+         {
+            png_controlp control = png_voidcast(png_controlp,
+               png_malloc_warn(png_ptr, (sizeof *control)));
+
+            if (control != NULL)
+            {
+               memset(control, 0, (sizeof *control));
+
+               control->png_ptr = png_ptr;
+               control->info_ptr = info_ptr;
+               control->for_write = 0;
+
+               image->opaque = control;
+               return 1;
+            }
+
+            /* Error clean up */
+            png_destroy_info_struct(png_ptr, &info_ptr);
+         }
+
+         png_destroy_read_struct(&png_ptr, NULL, NULL);
+      }
+
+      return png_image_error(image, "png_image_read: out of memory");
+   }
+
+   return png_image_error(image, "png_image_read: opaque pointer not NULL");
+}
+
+/* Utility to find the base format of a PNG file from a png_struct. */
+static png_uint_32
+png_image_format(png_structrp png_ptr)
+{
+   png_uint_32 format = 0;
+
+   if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
+      format |= PNG_FORMAT_FLAG_COLOR;
+
+   if ((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
+      format |= PNG_FORMAT_FLAG_ALPHA;
+
+   /* Use png_ptr here, not info_ptr, because by examination png_handle_tRNS
+    * sets the png_struct fields; that's all we are interested in here.  The
+    * precise interaction with an app call to png_set_tRNS and PNG file reading
+    * is unclear.
+    */
+   else if (png_ptr->num_trans > 0)
+      format |= PNG_FORMAT_FLAG_ALPHA;
+
+   if (png_ptr->bit_depth == 16)
+      format |= PNG_FORMAT_FLAG_LINEAR;
+
+   if ((png_ptr->color_type & PNG_COLOR_MASK_PALETTE) != 0)
+      format |= PNG_FORMAT_FLAG_COLORMAP;
+
+   return format;
+}
+
+/* Is the given gamma significantly different from sRGB?  The test is the same
+ * one used in pngrtran.c when deciding whether to do gamma correction.  The
+ * arithmetic optimizes the division by using the fact that the inverse of the
+ * file sRGB gamma is 2.2
+ */
+static int
+png_gamma_not_sRGB(png_fixed_point g)
+{
+   if (g < PNG_FP_1)
+   {
+      /* An uninitialized gamma is assumed to be sRGB for the simplified API. */
+      if (g == 0)
+         return 0;
+
+      return png_gamma_significant((g * 11 + 2)/5 /* i.e. *2.2, rounded */);
+   }
+
+   return 1;
+}
+
+/* Do the main body of a 'png_image_begin_read' function; read the PNG file
+ * header and fill in all the information.  This is executed in a safe context,
+ * unlike the init routine above.
+ */
+static int
+png_image_read_header(png_voidp argument)
+{
+   png_imagep image = png_voidcast(png_imagep, argument);
+   png_structrp png_ptr = image->opaque->png_ptr;
+   png_inforp info_ptr = image->opaque->info_ptr;
+
+   png_set_benign_errors(png_ptr, 1/*warn*/);
+   png_read_info(png_ptr, info_ptr);
+
+   /* Do this the fast way; just read directly out of png_struct. */
+   image->width = png_ptr->width;
+   image->height = png_ptr->height;
+
+   {
+      png_uint_32 format = png_image_format(png_ptr);
+
+      image->format = format;
+
+#ifdef PNG_COLORSPACE_SUPPORTED
+      /* Does the colorspace match sRGB?  If there is no color endpoint
+       * (colorant) information assume yes, otherwise require the
+       * 'ENDPOINTS_MATCHP_sRGB' colorspace flag to have been set.  If the
+       * colorspace has been determined to be invalid ignore it.
+       */
+      if ((format & PNG_FORMAT_FLAG_COLOR) != 0 && ((png_ptr->colorspace.flags
+         & (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB|
+            PNG_COLORSPACE_INVALID)) == PNG_COLORSPACE_HAVE_ENDPOINTS))
+         image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB;
+#endif
+   }
+
+   /* We need the maximum number of entries regardless of the format the
+    * application sets here.
+    */
+   {
+      png_uint_32 cmap_entries;
+
+      switch (png_ptr->color_type)
+      {
+         case PNG_COLOR_TYPE_GRAY:
+            cmap_entries = 1U << png_ptr->bit_depth;
+            break;
+
+         case PNG_COLOR_TYPE_PALETTE:
+            cmap_entries = png_ptr->num_palette;
+            break;
+
+         default:
+            cmap_entries = 256;
+            break;
+      }
+
+      if (cmap_entries > 256)
+         cmap_entries = 256;
+
+      image->colormap_entries = cmap_entries;
+   }
+
+   return 1;
+}
+
+#ifdef PNG_STDIO_SUPPORTED
+int PNGAPI
+png_image_begin_read_from_stdio(png_imagep image, FILE* file)
+{
+   if (image != NULL && image->version == PNG_IMAGE_VERSION)
+   {
+      if (file != NULL)
+      {
+         if (png_image_read_init(image) != 0)
+         {
+            /* This is slightly evil, but png_init_io doesn't do anything other
+             * than this and we haven't changed the standard IO functions so
+             * this saves a 'safe' function.
+             */
+            image->opaque->png_ptr->io_ptr = file;
+            return png_safe_execute(image, png_image_read_header, image);
+         }
+      }
+
+      else
+         return png_image_error(image,
+            "png_image_begin_read_from_stdio: invalid argument");
+   }
+
+   else if (image != NULL)
+      return png_image_error(image,
+         "png_image_begin_read_from_stdio: incorrect PNG_IMAGE_VERSION");
+
+   return 0;
+}
+
+int PNGAPI
+png_image_begin_read_from_file(png_imagep image, const char *file_name)
+{
+   if (image != NULL && image->version == PNG_IMAGE_VERSION)
+   {
+      if (file_name != NULL)
+      {
+         FILE *fp = fopen(file_name, "rb");
+
+         if (fp != NULL)
+         {
+            if (png_image_read_init(image) != 0)
+            {
+               image->opaque->png_ptr->io_ptr = fp;
+               image->opaque->owned_file = 1;
+               return png_safe_execute(image, png_image_read_header, image);
+            }
+
+            /* Clean up: just the opened file. */
+            (void)fclose(fp);
+         }
+
+         else
+            return png_image_error(image, strerror(errno));
+      }
+
+      else
+         return png_image_error(image,
+            "png_image_begin_read_from_file: invalid argument");
+   }
+
+   else if (image != NULL)
+      return png_image_error(image,
+         "png_image_begin_read_from_file: incorrect PNG_IMAGE_VERSION");
+
+   return 0;
+}
+#endif /* STDIO */
+
+static void PNGCBAPI
+png_image_memory_read(png_structp png_ptr, png_bytep out, png_size_t need)
+{
+   if (png_ptr != NULL)
+   {
+      png_imagep image = png_voidcast(png_imagep, png_ptr->io_ptr);
+      if (image != NULL)
+      {
+         png_controlp cp = image->opaque;
+         if (cp != NULL)
+         {
+            png_const_bytep memory = cp->memory;
+            png_size_t size = cp->size;
+
+            if (memory != NULL && size >= need)
+            {
+               memcpy(out, memory, need);
+               cp->memory = memory + need;
+               cp->size = size - need;
+               return;
+            }
+
+            png_error(png_ptr, "read beyond end of data");
+         }
+      }
+
+      png_error(png_ptr, "invalid memory read");
+   }
+}
+
+int PNGAPI png_image_begin_read_from_memory(png_imagep image,
+   png_const_voidp memory, png_size_t size)
+{
+   if (image != NULL && image->version == PNG_IMAGE_VERSION)
+   {
+      if (memory != NULL && size > 0)
+      {
+         if (png_image_read_init(image) != 0)
+         {
+            /* Now set the IO functions to read from the memory buffer and
+             * store it into io_ptr.  Again do this in-place to avoid calling a
+             * libpng function that requires error handling.
+             */
+            image->opaque->memory = png_voidcast(png_const_bytep, memory);
+            image->opaque->size = size;
+            image->opaque->png_ptr->io_ptr = image;
+            image->opaque->png_ptr->read_data_fn = png_image_memory_read;
+
+            return png_safe_execute(image, png_image_read_header, image);
+         }
+      }
+
+      else
+         return png_image_error(image,
+            "png_image_begin_read_from_memory: invalid argument");
+   }
+
+   else if (image != NULL)
+      return png_image_error(image,
+         "png_image_begin_read_from_memory: incorrect PNG_IMAGE_VERSION");
+
+   return 0;
+}
+
+/* Utility function to skip chunks that are not used by the simplified image
+ * read functions and an appropriate macro to call it.
+ */
+#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+static void
+png_image_skip_unused_chunks(png_structrp png_ptr)
+{
+   /* Prepare the reader to ignore all recognized chunks whose data will not
+    * be used, i.e., all chunks recognized by libpng except for those
+    * involved in basic image reading:
+    *
+    *    IHDR, PLTE, IDAT, IEND
+    *
+    * Or image data handling:
+    *
+    *    tRNS, bKGD, gAMA, cHRM, sRGB, [iCCP] and sBIT.
+    *
+    * This provides a small performance improvement and eliminates any
+    * potential vulnerability to security problems in the unused chunks.
+    *
+    * At present the iCCP chunk data isn't used, so iCCP chunk can be ignored
+    * too.  This allows the simplified API to be compiled without iCCP support,
+    * however if the support is there the chunk is still checked to detect
+    * errors (which are unfortunately quite common.)
+    */
+   {
+         static PNG_CONST png_byte chunks_to_process[] = {
+            98,  75,  71,  68, '\0',  /* bKGD */
+            99,  72,  82,  77, '\0',  /* cHRM */
+           103,  65,  77,  65, '\0',  /* gAMA */
+#        ifdef PNG_READ_iCCP_SUPPORTED
+           105,  67,  67,  80, '\0',  /* iCCP */
+#        endif
+           115,  66,  73,  84, '\0',  /* sBIT */
+           115,  82,  71,  66, '\0',  /* sRGB */
+           };
+
+       /* Ignore unknown chunks and all other chunks except for the
+        * IHDR, PLTE, tRNS, IDAT, and IEND chunks.
+        */
+       png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_NEVER,
+         NULL, -1);
+
+       /* But do not ignore image data handling chunks */
+       png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_AS_DEFAULT,
+         chunks_to_process, (int)/*SAFE*/(sizeof chunks_to_process)/5);
+    }
+}
+
+#  define PNG_SKIP_CHUNKS(p) png_image_skip_unused_chunks(p)
+#else
+#  define PNG_SKIP_CHUNKS(p) ((void)0)
+#endif /* HANDLE_AS_UNKNOWN */
+
+/* The following macro gives the exact rounded answer for all values in the
+ * range 0..255 (it actually divides by 51.2, but the rounding still generates
+ * the correct numbers 0..5
+ */
+#define PNG_DIV51(v8) (((v8) * 5 + 130) >> 8)
+
+/* Utility functions to make particular color-maps */
+static void
+set_file_encoding(png_image_read_control *display)
+{
+   png_fixed_point g = display->image->opaque->png_ptr->colorspace.gamma;
+   if (png_gamma_significant(g) != 0)
+   {
+      if (png_gamma_not_sRGB(g) != 0)
+      {
+         display->file_encoding = P_FILE;
+         display->gamma_to_linear = png_reciprocal(g);
+      }
+
+      else
+         display->file_encoding = P_sRGB;
+   }
+
+   else
+      display->file_encoding = P_LINEAR8;
+}
+
+static unsigned int
+decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding)
+{
+   if (encoding == P_FILE) /* double check */
+      encoding = display->file_encoding;
+
+   if (encoding == P_NOTSET) /* must be the file encoding */
+   {
+      set_file_encoding(display);
+      encoding = display->file_encoding;
+   }
+
+   switch (encoding)
+   {
+      case P_FILE:
+         value = png_gamma_16bit_correct(value*257, display->gamma_to_linear);
+         break;
+
+      case P_sRGB:
+         value = png_sRGB_table[value];
+         break;
+
+      case P_LINEAR:
+         break;
+
+      case P_LINEAR8:
+         value *= 257;
+         break;
+
+      default:
+         png_error(display->image->opaque->png_ptr,
+            "unexpected encoding (internal error)");
+         break;
+   }
+
+   return value;
+}
+
+static png_uint_32
+png_colormap_compose(png_image_read_control *display,
+   png_uint_32 foreground, int foreground_encoding, png_uint_32 alpha,
+   png_uint_32 background, int encoding)
+{
+   /* The file value is composed on the background, the background has the given
+    * encoding and so does the result, the file is encoded with P_FILE and the
+    * file and alpha are 8-bit values.  The (output) encoding will always be
+    * P_LINEAR or P_sRGB.
+    */
+   png_uint_32 f = decode_gamma(display, foreground, foreground_encoding);
+   png_uint_32 b = decode_gamma(display, background, encoding);
+
+   /* The alpha is always an 8-bit value (it comes from the palette), the value
+    * scaled by 255 is what PNG_sRGB_FROM_LINEAR requires.
+    */
+   f = f * alpha + b * (255-alpha);
+
+   if (encoding == P_LINEAR)
+   {
+      /* Scale to 65535; divide by 255, approximately (in fact this is extremely
+       * accurate, it divides by 255.00000005937181414556, with no overflow.)
+       */
+      f *= 257; /* Now scaled by 65535 */
+      f += f >> 16;
+      f = (f+32768) >> 16;
+   }
+
+   else /* P_sRGB */
+      f = PNG_sRGB_FROM_LINEAR(f);
+
+   return f;
+}
+
+/* NOTE: P_LINEAR values to this routine must be 16-bit, but P_FILE values must
+ * be 8-bit.
+ */
+static void
+png_create_colormap_entry(png_image_read_control *display,
+   png_uint_32 ip, png_uint_32 red, png_uint_32 green, png_uint_32 blue,
+   png_uint_32 alpha, int encoding)
+{
+   png_imagep image = display->image;
+   const int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
+      P_LINEAR : P_sRGB;
+   const int convert_to_Y = (image->format & PNG_FORMAT_FLAG_COLOR) == 0 &&
+      (red != green || green != blue);
+
+   if (ip > 255)
+      png_error(image->opaque->png_ptr, "color-map index out of range");
+
+   /* Update the cache with whether the file gamma is significantly different
+    * from sRGB.
+    */
+   if (encoding == P_FILE)
+   {
+      if (display->file_encoding == P_NOTSET)
+         set_file_encoding(display);
+
+      /* Note that the cached value may be P_FILE too, but if it is then the
+       * gamma_to_linear member has been set.
+       */
+      encoding = display->file_encoding;
+   }
+
+   if (encoding == P_FILE)
+   {
+      png_fixed_point g = display->gamma_to_linear;
+
+      red = png_gamma_16bit_correct(red*257, g);
+      green = png_gamma_16bit_correct(green*257, g);
+      blue = png_gamma_16bit_correct(blue*257, g);
+
+      if (convert_to_Y != 0 || output_encoding == P_LINEAR)
+      {
+         alpha *= 257;
+         encoding = P_LINEAR;
+      }
+
+      else
+      {
+         red = PNG_sRGB_FROM_LINEAR(red * 255);
+         green = PNG_sRGB_FROM_LINEAR(green * 255);
+         blue = PNG_sRGB_FROM_LINEAR(blue * 255);
+         encoding = P_sRGB;
+      }
+   }
+
+   else if (encoding == P_LINEAR8)
+   {
+      /* This encoding occurs quite frequently in test cases because PngSuite
+       * includes a gAMA 1.0 chunk with most images.
+       */
+      red *= 257;
+      green *= 257;
+      blue *= 257;
+      alpha *= 257;
+      encoding = P_LINEAR;
+   }
+
+   else if (encoding == P_sRGB &&
+       (convert_to_Y  != 0 || output_encoding == P_LINEAR))
+   {
+      /* The values are 8-bit sRGB values, but must be converted to 16-bit
+       * linear.
+       */
+      red = png_sRGB_table[red];
+      green = png_sRGB_table[green];
+      blue = png_sRGB_table[blue];
+      alpha *= 257;
+      encoding = P_LINEAR;
+   }
+
+   /* This is set if the color isn't gray but the output is. */
+   if (encoding == P_LINEAR)
+   {
+      if (convert_to_Y != 0)
+      {
+         /* NOTE: these values are copied from png_do_rgb_to_gray */
+         png_uint_32 y = (png_uint_32)6968 * red  + (png_uint_32)23434 * green +
+            (png_uint_32)2366 * blue;
+
+         if (output_encoding == P_LINEAR)
+            y = (y + 16384) >> 15;
+
+         else
+         {
+            /* y is scaled by 32768, we need it scaled by 255: */
+            y = (y + 128) >> 8;
+            y *= 255;
+            y = PNG_sRGB_FROM_LINEAR((y + 64) >> 7);
+            alpha = PNG_DIV257(alpha);
+            encoding = P_sRGB;
+         }
 
+         blue = red = green = y;
+      }
+
+      else if (output_encoding == P_sRGB)
+      {
+         red = PNG_sRGB_FROM_LINEAR(red * 255);
+         green = PNG_sRGB_FROM_LINEAR(green * 255);
+         blue = PNG_sRGB_FROM_LINEAR(blue * 255);
+         alpha = PNG_DIV257(alpha);
+         encoding = P_sRGB;
+      }
+   }
+
+   if (encoding != output_encoding)
+      png_error(image->opaque->png_ptr, "bad encoding (internal error)");
+
+   /* Store the value. */
+   {
+#     ifdef PNG_FORMAT_AFIRST_SUPPORTED
+         const int afirst = (image->format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
+            (image->format & PNG_FORMAT_FLAG_ALPHA) != 0;
+#     else
+#        define afirst 0
+#     endif
+#     ifdef PNG_FORMAT_BGR_SUPPORTED
+         const int bgr = (image->format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0;
+#     else
+#        define bgr 0
+#     endif
+
+      if (output_encoding == P_LINEAR)
+      {
+         png_uint_16p entry = png_voidcast(png_uint_16p, display->colormap);
+
+         entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
+
+         /* The linear 16-bit values must be pre-multiplied by the alpha channel
+          * value, if less than 65535 (this is, effectively, composite on black
+          * if the alpha channel is removed.)
+          */
+         switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
+         {
+            case 4:
+               entry[afirst ? 0 : 3] = (png_uint_16)alpha;
+               /* FALL THROUGH */
+
+            case 3:
+               if (alpha < 65535)
+               {
+                  if (alpha > 0)
+                  {
+                     blue = (blue * alpha + 32767U)/65535U;
+                     green = (green * alpha + 32767U)/65535U;
+                     red = (red * alpha + 32767U)/65535U;
+                  }
+
+                  else
+                     red = green = blue = 0;
+               }
+               entry[afirst + (2 ^ bgr)] = (png_uint_16)blue;
+               entry[afirst + 1] = (png_uint_16)green;
+               entry[afirst + bgr] = (png_uint_16)red;
+               break;
+
+            case 2:
+               entry[1 ^ afirst] = (png_uint_16)alpha;
+               /* FALL THROUGH */
+
+            case 1:
+               if (alpha < 65535)
+               {
+                  if (alpha > 0)
+                     green = (green * alpha + 32767U)/65535U;
+
+                  else
+                     green = 0;
+               }
+               entry[afirst] = (png_uint_16)green;
+               break;
+
+            default:
+               break;
+         }
+      }
+
+      else /* output encoding is P_sRGB */
+      {
+         png_bytep entry = png_voidcast(png_bytep, display->colormap);
+
+         entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
+
+         switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
+         {
+            case 4:
+               entry[afirst ? 0 : 3] = (png_byte)alpha;
+            case 3:
+               entry[afirst + (2 ^ bgr)] = (png_byte)blue;
+               entry[afirst + 1] = (png_byte)green;
+               entry[afirst + bgr] = (png_byte)red;
+               break;
+
+            case 2:
+               entry[1 ^ afirst] = (png_byte)alpha;
+            case 1:
+               entry[afirst] = (png_byte)green;
+               break;
+
+            default:
+               break;
+         }
+      }
+
+#     ifdef afirst
+#        undef afirst
+#     endif
+#     ifdef bgr
+#        undef bgr
+#     endif
+   }
+}
+
+static int
+make_gray_file_colormap(png_image_read_control *display)
+{
+   unsigned int i;
+
+   for (i=0; i<256; ++i)
+      png_create_colormap_entry(display, i, i, i, i, 255, P_FILE);
+
+   return i;
+}
+
+static int
+make_gray_colormap(png_image_read_control *display)
+{
+   unsigned int i;
+
+   for (i=0; i<256; ++i)
+      png_create_colormap_entry(display, i, i, i, i, 255, P_sRGB);
+
+   return i;
+}
+#define PNG_GRAY_COLORMAP_ENTRIES 256
+
+static int
+make_ga_colormap(png_image_read_control *display)
+{
+   unsigned int i, a;
+
+   /* Alpha is retained, the output will be a color-map with entries
+    * selected by six levels of alpha.  One transparent entry, 6 gray
+    * levels for all the intermediate alpha values, leaving 230 entries
+    * for the opaque grays.  The color-map entries are the six values
+    * [0..5]*51, the GA processing uses PNG_DIV51(value) to find the
+    * relevant entry.
+    *
+    * if (alpha > 229) // opaque
+    * {
+    *    // The 231 entries are selected to make the math below work:
+    *    base = 0;
+    *    entry = (231 * gray + 128) >> 8;
+    * }
+    * else if (alpha < 26) // transparent
+    * {
+    *    base = 231;
+    *    entry = 0;
+    * }
+    * else // partially opaque
+    * {
+    *    base = 226 + 6 * PNG_DIV51(alpha);
+    *    entry = PNG_DIV51(gray);
+    * }
+    */
+   i = 0;
+   while (i < 231)
+   {
+      unsigned int gray = (i * 256 + 115) / 231;
+      png_create_colormap_entry(display, i++, gray, gray, gray, 255, P_sRGB);
+   }
+
+   /* 255 is used here for the component values for consistency with the code
+    * that undoes premultiplication in pngwrite.c.
+    */
+   png_create_colormap_entry(display, i++, 255, 255, 255, 0, P_sRGB);
+
+   for (a=1; a<5; ++a)
+   {
+      unsigned int g;
+
+      for (g=0; g<6; ++g)
+         png_create_colormap_entry(display, i++, g*51, g*51, g*51, a*51,
+            P_sRGB);
+   }
+
+   return i;
+}
+
+#define PNG_GA_COLORMAP_ENTRIES 256
+
+static int
+make_rgb_colormap(png_image_read_control *display)
+{
+   unsigned int i, r;
+
+   /* Build a 6x6x6 opaque RGB cube */
+   for (i=r=0; r<6; ++r)
+   {
+      unsigned int g;
+
+      for (g=0; g<6; ++g)
+      {
+         unsigned int b;
+
+         for (b=0; b<6; ++b)
+            png_create_colormap_entry(display, i++, r*51, g*51, b*51, 255,
+               P_sRGB);
+      }
+   }
+
+   return i;
+}
+
+#define PNG_RGB_COLORMAP_ENTRIES 216
+
+/* Return a palette index to the above palette given three 8-bit sRGB values. */
+#define PNG_RGB_INDEX(r,g,b) \
+   ((png_byte)(6 * (6 * PNG_DIV51(r) + PNG_DIV51(g)) + PNG_DIV51(b)))
+
+static int
+png_image_read_colormap(png_voidp argument)
+{
+   png_image_read_control *display =
+      png_voidcast(png_image_read_control*, argument);
+   const png_imagep image = display->image;
+
+   const png_structrp png_ptr = image->opaque->png_ptr;
+   const png_uint_32 output_format = image->format;
+   const int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
+      P_LINEAR : P_sRGB;
+
+   unsigned int cmap_entries;
+   unsigned int output_processing;        /* Output processing option */
+   unsigned int data_encoding = P_NOTSET; /* Encoding libpng must produce */
+
+   /* Background information; the background color and the index of this color
+    * in the color-map if it exists (else 256).
+    */
+   unsigned int background_index = 256;
+   png_uint_32 back_r, back_g, back_b;
+
+   /* Flags to accumulate things that need to be done to the input. */
+   int expand_tRNS = 0;
+
+   /* Exclude the NYI feature of compositing onto a color-mapped buffer; it is
+    * very difficult to do, the results look awful, and it is difficult to see
+    * what possible use it is because the application can't control the
+    * color-map.
+    */
+   if (((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0 ||
+         png_ptr->num_trans > 0) /* alpha in input */ &&
+      ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) /* no alpha in output */)
+   {
+      if (output_encoding == P_LINEAR) /* compose on black */
+         back_b = back_g = back_r = 0;
+
+      else if (display->background == NULL /* no way to remove it */)
+         png_error(png_ptr,
+            "a background color must be supplied to remove alpha/transparency");
+
+      /* Get a copy of the background color (this avoids repeating the checks
+       * below.)  The encoding is 8-bit sRGB or 16-bit linear, depending on the
+       * output format.
+       */
+      else
+      {
+         back_g = display->background->green;
+         if ((output_format & PNG_FORMAT_FLAG_COLOR) != 0)
+         {
+            back_r = display->background->red;
+            back_b = display->background->blue;
+         }
+         else
+            back_b = back_r = back_g;
+      }
+   }
+
+   else if (output_encoding == P_LINEAR)
+      back_b = back_r = back_g = 65535;
+
+   else
+      back_b = back_r = back_g = 255;
+
+   /* Default the input file gamma if required - this is necessary because
+    * libpng assumes that if no gamma information is present the data is in the
+    * output format, but the simplified API deduces the gamma from the input
+    * format.
+    */
+   if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) == 0)
+   {
+      /* Do this directly, not using the png_colorspace functions, to ensure
+       * that it happens even if the colorspace is invalid (though probably if
+       * it is the setting will be ignored)  Note that the same thing can be
+       * achieved at the application interface with png_set_gAMA.
+       */
+      if (png_ptr->bit_depth == 16 &&
+         (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
+         png_ptr->colorspace.gamma = PNG_GAMMA_LINEAR;
+
+      else
+         png_ptr->colorspace.gamma = PNG_GAMMA_sRGB_INVERSE;
+
+      png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
+   }
+
+   /* Decide what to do based on the PNG color type of the input data.  The
+    * utility function png_create_colormap_entry deals with most aspects of the
+    * output transformations; this code works out how to produce bytes of
+    * color-map entries from the original format.
+    */
+   switch (png_ptr->color_type)
+   {
+      case PNG_COLOR_TYPE_GRAY:
+         if (png_ptr->bit_depth <= 8)
+         {
+            /* There at most 256 colors in the output, regardless of
+             * transparency.
+             */
+            unsigned int step, i, val, trans = 256/*ignore*/, back_alpha = 0;
+
+            cmap_entries = 1U << png_ptr->bit_depth;
+            if (cmap_entries > image->colormap_entries)
+               png_error(png_ptr, "gray[8] color-map: too few entries");
+
+            step = 255 / (cmap_entries - 1);
+            output_processing = PNG_CMAP_NONE;
+
+            /* If there is a tRNS chunk then this either selects a transparent
+             * value or, if the output has no alpha, the background color.
+             */
+            if (png_ptr->num_trans > 0)
+            {
+               trans = png_ptr->trans_color.gray;
+
+               if ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0)
+                  back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
+            }
+
+            /* png_create_colormap_entry just takes an RGBA and writes the
+             * corresponding color-map entry using the format from 'image',
+             * including the required conversion to sRGB or linear as
+             * appropriate.  The input values are always either sRGB (if the
+             * gamma correction flag is 0) or 0..255 scaled file encoded values
+             * (if the function must gamma correct them).
+             */
+            for (i=val=0; i<cmap_entries; ++i, val += step)
+            {
+               /* 'i' is a file value.  While this will result in duplicated
+                * entries for 8-bit non-sRGB encoded files it is necessary to
+                * have non-gamma corrected values to do tRNS handling.
+                */
+               if (i != trans)
+                  png_create_colormap_entry(display, i, val, val, val, 255,
+                     P_FILE/*8-bit with file gamma*/);
+
+               /* Else this entry is transparent.  The colors don't matter if
+                * there is an alpha channel (back_alpha == 0), but it does no
+                * harm to pass them in; the values are not set above so this
+                * passes in white.
+                *
+                * NOTE: this preserves the full precision of the application
+                * supplied background color when it is used.
+                */
+               else
+                  png_create_colormap_entry(display, i, back_r, back_g, back_b,
+                     back_alpha, output_encoding);
+            }
+
+            /* We need libpng to preserve the original encoding. */
+            data_encoding = P_FILE;
+
+            /* The rows from libpng, while technically gray values, are now also
+             * color-map indices; however, they may need to be expanded to 1
+             * byte per pixel.  This is what png_set_packing does (i.e., it
+             * unpacks the bit values into bytes.)
+             */
+            if (png_ptr->bit_depth < 8)
+               png_set_packing(png_ptr);
+         }
+
+         else /* bit depth is 16 */
+         {
+            /* The 16-bit input values can be converted directly to 8-bit gamma
+             * encoded values; however, if a tRNS chunk is present 257 color-map
+             * entries are required.  This means that the extra entry requires
+             * special processing; add an alpha channel, sacrifice gray level
+             * 254 and convert transparent (alpha==0) entries to that.
+             *
+             * Use libpng to chop the data to 8 bits.  Convert it to sRGB at the
+             * same time to minimize quality loss.  If a tRNS chunk is present
+             * this means libpng must handle it too; otherwise it is impossible
+             * to do the exact match on the 16-bit value.
+             *
+             * If the output has no alpha channel *and* the background color is
+             * gray then it is possible to let libpng handle the substitution by
+             * ensuring that the corresponding gray level matches the background
+             * color exactly.
+             */
+            data_encoding = P_sRGB;
+
+            if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
+               png_error(png_ptr, "gray[16] color-map: too few entries");
+
+            cmap_entries = make_gray_colormap(display);
+
+            if (png_ptr->num_trans > 0)
+            {
+               unsigned int back_alpha;
+
+               if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
+                  back_alpha = 0;
+
+               else
+               {
+                  if (back_r == back_g && back_g == back_b)
+                  {
+                     /* Background is gray; no special processing will be
+                      * required.
+                      */
+                     png_color_16 c;
+                     png_uint_32 gray = back_g;
+
+                     if (output_encoding == P_LINEAR)
+                     {
+                        gray = PNG_sRGB_FROM_LINEAR(gray * 255);
+
+                        /* And make sure the corresponding palette entry
+                         * matches.
+                         */
+                        png_create_colormap_entry(display, gray, back_g, back_g,
+                           back_g, 65535, P_LINEAR);
+                     }
+
+                     /* The background passed to libpng, however, must be the
+                      * sRGB value.
+                      */
+                     c.index = 0; /*unused*/
+                     c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
+
+                     /* NOTE: does this work without expanding tRNS to alpha?
+                      * It should be the color->gray case below apparently
+                      * doesn't.
+                      */
+                     png_set_background_fixed(png_ptr, &c,
+                        PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
+                        0/*gamma: not used*/);
+
+                     output_processing = PNG_CMAP_NONE;
+                     break;
+                  }
+#ifdef __COVERITY__
+                 /* Coverity claims that output_encoding cannot be 2 (P_LINEAR)
+                  * here.
+                  */
+                  back_alpha = 255;
+#else
+                  back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
+#endif
+               }
+
+               /* output_processing means that the libpng-processed row will be
+                * 8-bit GA and it has to be processing to single byte color-map
+                * values.  Entry 254 is replaced by either a completely
+                * transparent entry or by the background color at full
+                * precision (and the background color is not a simple gray
+                * level in this case.)
+                */
+               expand_tRNS = 1;
+               output_processing = PNG_CMAP_TRANS;
+               background_index = 254;
+
+               /* And set (overwrite) color-map entry 254 to the actual
+                * background color at full precision.
+                */
+               png_create_colormap_entry(display, 254, back_r, back_g, back_b,
+                  back_alpha, output_encoding);
+            }
+
+            else
+               output_processing = PNG_CMAP_NONE;
+         }
+         break;
+
+      case PNG_COLOR_TYPE_GRAY_ALPHA:
+         /* 8-bit or 16-bit PNG with two channels - gray and alpha.  A minimum
+          * of 65536 combinations.  If, however, the alpha channel is to be
+          * removed there are only 256 possibilities if the background is gray.
+          * (Otherwise there is a subset of the 65536 possibilities defined by
+          * the triangle between black, white and the background color.)
+          *
+          * Reduce 16-bit files to 8-bit and sRGB encode the result.  No need to
+          * worry about tRNS matching - tRNS is ignored if there is an alpha
+          * channel.
+          */
+         data_encoding = P_sRGB;
+
+         if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
+         {
+            if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
+               png_error(png_ptr, "gray+alpha color-map: too few entries");
+
+            cmap_entries = make_ga_colormap(display);
+
+            background_index = PNG_CMAP_GA_BACKGROUND;
+            output_processing = PNG_CMAP_GA;
+         }
+
+         else /* alpha is removed */
+         {
+            /* Alpha must be removed as the PNG data is processed when the
+             * background is a color because the G and A channels are
+             * independent and the vector addition (non-parallel vectors) is a
+             * 2-D problem.
+             *
+             * This can be reduced to the same algorithm as above by making a
+             * colormap containing gray levels (for the opaque grays), a
+             * background entry (for a transparent pixel) and a set of four six
+             * level color values, one set for each intermediate alpha value.
+             * See the comments in make_ga_colormap for how this works in the
+             * per-pixel processing.
+             *
+             * If the background is gray, however, we only need a 256 entry gray
+             * level color map.  It is sufficient to make the entry generated
+             * for the background color be exactly the color specified.
+             */
+            if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0 ||
+               (back_r == back_g && back_g == back_b))
+            {
+               /* Background is gray; no special processing will be required. */
+               png_color_16 c;
+               png_uint_32 gray = back_g;
+
+               if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
+                  png_error(png_ptr, "gray-alpha color-map: too few entries");
+
+               cmap_entries = make_gray_colormap(display);
+
+               if (output_encoding == P_LINEAR)
+               {
+                  gray = PNG_sRGB_FROM_LINEAR(gray * 255);
+
+                  /* And make sure the corresponding palette entry matches. */
+                  png_create_colormap_entry(display, gray, back_g, back_g,
+                     back_g, 65535, P_LINEAR);
+               }
+
+               /* The background passed to libpng, however, must be the sRGB
+                * value.
+                */
+               c.index = 0; /*unused*/
+               c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
+
+               png_set_background_fixed(png_ptr, &c,
+                  PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
+                  0/*gamma: not used*/);
+
+               output_processing = PNG_CMAP_NONE;
+            }
+
+            else
+            {
+               png_uint_32 i, a;
+
+               /* This is the same as png_make_ga_colormap, above, except that
+                * the entries are all opaque.
+                */
+               if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
+                  png_error(png_ptr, "ga-alpha color-map: too few entries");
+
+               i = 0;
+               while (i < 231)
+               {
+                  png_uint_32 gray = (i * 256 + 115) / 231;
+                  png_create_colormap_entry(display, i++, gray, gray, gray,
+                     255, P_sRGB);
+               }
+
+               /* NOTE: this preserves the full precision of the application
+                * background color.
+                */
+               background_index = i;
+               png_create_colormap_entry(display, i++, back_r, back_g, back_b,
+#ifdef __COVERITY__
+                 /* Coverity claims that output_encoding cannot be 2 (P_LINEAR)
+                  * here.
+                  */ 255U,
+#else
+                  output_encoding == P_LINEAR ? 65535U : 255U,
+#endif
+                  output_encoding);
+
+               /* For non-opaque input composite on the sRGB background - this
+                * requires inverting the encoding for each component.  The input
+                * is still converted to the sRGB encoding because this is a
+                * reasonable approximate to the logarithmic curve of human
+                * visual sensitivity, at least over the narrow range which PNG
+                * represents.  Consequently 'G' is always sRGB encoded, while
+                * 'A' is linear.  We need the linear background colors.
+                */
+               if (output_encoding == P_sRGB) /* else already linear */
+               {
+                  /* This may produce a value not exactly matching the
+                   * background, but that's ok because these numbers are only
+                   * used when alpha != 0
+                   */
+                  back_r = png_sRGB_table[back_r];
+                  back_g = png_sRGB_table[back_g];
+                  back_b = png_sRGB_table[back_b];
+               }
+
+               for (a=1; a<5; ++a)
+               {
+                  unsigned int g;
+
+                  /* PNG_sRGB_FROM_LINEAR expects a 16-bit linear value scaled
+                   * by an 8-bit alpha value (0..255).
+                   */
+                  png_uint_32 alpha = 51 * a;
+                  png_uint_32 back_rx = (255-alpha) * back_r;
+                  png_uint_32 back_gx = (255-alpha) * back_g;
+                  png_uint_32 back_bx = (255-alpha) * back_b;
+
+                  for (g=0; g<6; ++g)
+                  {
+                     png_uint_32 gray = png_sRGB_table[g*51] * alpha;
+
+                     png_create_colormap_entry(display, i++,
+                        PNG_sRGB_FROM_LINEAR(gray + back_rx),
+                        PNG_sRGB_FROM_LINEAR(gray + back_gx),
+                        PNG_sRGB_FROM_LINEAR(gray + back_bx), 255, P_sRGB);
+                  }
+               }
+
+               cmap_entries = i;
+               output_processing = PNG_CMAP_GA;
+            }
+         }
+         break;
+
+      case PNG_COLOR_TYPE_RGB:
+      case PNG_COLOR_TYPE_RGB_ALPHA:
+         /* Exclude the case where the output is gray; we can always handle this
+          * with the cases above.
+          */
+         if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0)
+         {
+            /* The color-map will be grayscale, so we may as well convert the
+             * input RGB values to a simple grayscale and use the grayscale
+             * code above.
+             *
+             * NOTE: calling this apparently damages the recognition of the
+             * transparent color in background color handling; call
+             * png_set_tRNS_to_alpha before png_set_background_fixed.
+             */
+            png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, -1,
+               -1);
+            data_encoding = P_sRGB;
+
+            /* The output will now be one or two 8-bit gray or gray+alpha
+             * channels.  The more complex case arises when the input has alpha.
+             */
+            if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
+               png_ptr->num_trans > 0) &&
+               (output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
+            {
+               /* Both input and output have an alpha channel, so no background
+                * processing is required; just map the GA bytes to the right
+                * color-map entry.
+                */
+               expand_tRNS = 1;
+
+               if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
+                  png_error(png_ptr, "rgb[ga] color-map: too few entries");
+
+               cmap_entries = make_ga_colormap(display);
+               background_index = PNG_CMAP_GA_BACKGROUND;
+               output_processing = PNG_CMAP_GA;
+            }
+
+            else
+            {
+               /* Either the input or the output has no alpha channel, so there
+                * will be no non-opaque pixels in the color-map; it will just be
+                * grayscale.
+                */
+               if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
+                  png_error(png_ptr, "rgb[gray] color-map: too few entries");
+
+               /* Ideally this code would use libpng to do the gamma correction,
+                * but if an input alpha channel is to be removed we will hit the
+                * libpng bug in gamma+compose+rgb-to-gray (the double gamma
+                * correction bug).  Fix this by dropping the gamma correction in
+                * this case and doing it in the palette; this will result in
+                * duplicate palette entries, but that's better than the
+                * alternative of double gamma correction.
+                */
+               if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
+                  png_ptr->num_trans > 0) &&
+                  png_gamma_not_sRGB(png_ptr->colorspace.gamma) != 0)
+               {
+                  cmap_entries = make_gray_file_colormap(display);
+                  data_encoding = P_FILE;
+               }
+
+               else
+                  cmap_entries = make_gray_colormap(display);
+
+               /* But if the input has alpha or transparency it must be removed
+                */
+               if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
+                  png_ptr->num_trans > 0)
+               {
+                  png_color_16 c;
+                  png_uint_32 gray = back_g;
+
+                  /* We need to ensure that the application background exists in
+                   * the colormap and that completely transparent pixels map to
+                   * it.  Achieve this simply by ensuring that the entry
+                   * selected for the background really is the background color.
+                   */
+                  if (data_encoding == P_FILE) /* from the fixup above */
+                  {
+                     /* The app supplied a gray which is in output_encoding, we
+                      * need to convert it to a value of the input (P_FILE)
+                      * encoding then set this palette entry to the required
+                      * output encoding.
+                      */
+                     if (output_encoding == P_sRGB)
+                        gray = png_sRGB_table[gray]; /* now P_LINEAR */
+
+                     gray = PNG_DIV257(png_gamma_16bit_correct(gray,
+                        png_ptr->colorspace.gamma)); /* now P_FILE */
+
+                     /* And make sure the corresponding palette entry contains
+                      * exactly the required sRGB value.
+                      */
+                     png_create_colormap_entry(display, gray, back_g, back_g,
+                        back_g, 0/*unused*/, output_encoding);
+                  }
+
+                  else if (output_encoding == P_LINEAR)
+                  {
+                     gray = PNG_sRGB_FROM_LINEAR(gray * 255);
+
+                     /* And make sure the corresponding palette entry matches.
+                      */
+                     png_create_colormap_entry(display, gray, back_g, back_g,
+                        back_g, 0/*unused*/, P_LINEAR);
+                  }
+
+                  /* The background passed to libpng, however, must be the
+                   * output (normally sRGB) value.
+                   */
+                  c.index = 0; /*unused*/
+                  c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
+
+                  /* NOTE: the following is apparently a bug in libpng. Without
+                   * it the transparent color recognition in
+                   * png_set_background_fixed seems to go wrong.
+                   */
+                  expand_tRNS = 1;
+                  png_set_background_fixed(png_ptr, &c,
+                     PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
+                     0/*gamma: not used*/);
+               }
+
+               output_processing = PNG_CMAP_NONE;
+            }
+         }
+
+         else /* output is color */
+         {
+            /* We could use png_quantize here so long as there is no transparent
+             * color or alpha; png_quantize ignores alpha.  Easier overall just
+             * to do it once and using PNG_DIV51 on the 6x6x6 reduced RGB cube.
+             * Consequently we always want libpng to produce sRGB data.
+             */
+            data_encoding = P_sRGB;
+
+            /* Is there any transparency or alpha? */
+            if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
+               png_ptr->num_trans > 0)
+            {
+               /* Is there alpha in the output too?  If so all four channels are
+                * processed into a special RGB cube with alpha support.
+                */
+               if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
+               {
+                  png_uint_32 r;
+
+                  if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
+                     png_error(png_ptr, "rgb+alpha color-map: too few entries");
+
+                  cmap_entries = make_rgb_colormap(display);
+
+                  /* Add a transparent entry. */
+                  png_create_colormap_entry(display, cmap_entries, 255, 255,
+                     255, 0, P_sRGB);
+
+                  /* This is stored as the background index for the processing
+                   * algorithm.
+                   */
+                  background_index = cmap_entries++;
+
+                  /* Add 27 r,g,b entries each with alpha 0.5. */
+                  for (r=0; r<256; r = (r << 1) | 0x7f)
+                  {
+                     png_uint_32 g;
+
+                     for (g=0; g<256; g = (g << 1) | 0x7f)
+                     {
+                        png_uint_32 b;
+
+                        /* This generates components with the values 0, 127 and
+                         * 255
+                         */
+                        for (b=0; b<256; b = (b << 1) | 0x7f)
+                           png_create_colormap_entry(display, cmap_entries++,
+                              r, g, b, 128, P_sRGB);
+                     }
+                  }
+
+                  expand_tRNS = 1;
+                  output_processing = PNG_CMAP_RGB_ALPHA;
+               }
+
+               else
+               {
+                  /* Alpha/transparency must be removed.  The background must
+                   * exist in the color map (achieved by setting adding it after
+                   * the 666 color-map).  If the standard processing code will
+                   * pick up this entry automatically that's all that is
+                   * required; libpng can be called to do the background
+                   * processing.
+                   */
+                  unsigned int sample_size =
+                     PNG_IMAGE_SAMPLE_SIZE(output_format);
+                  png_uint_32 r, g, b; /* sRGB background */
+
+                  if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
+                     png_error(png_ptr, "rgb-alpha color-map: too few entries");
+
+                  cmap_entries = make_rgb_colormap(display);
+
+                  png_create_colormap_entry(display, cmap_entries, back_r,
+                        back_g, back_b, 0/*unused*/, output_encoding);
+
+                  if (output_encoding == P_LINEAR)
+                  {
+                     r = PNG_sRGB_FROM_LINEAR(back_r * 255);
+                     g = PNG_sRGB_FROM_LINEAR(back_g * 255);
+                     b = PNG_sRGB_FROM_LINEAR(back_b * 255);
+                  }
+
+                  else
+                  {
+                     r = back_r;
+                     g = back_g;
+                     b = back_g;
+                  }
+
+                  /* Compare the newly-created color-map entry with the one the
+                   * PNG_CMAP_RGB algorithm will use.  If the two entries don't
+                   * match, add the new one and set this as the background
+                   * index.
+                   */
+                  if (memcmp((png_const_bytep)display->colormap +
+                        sample_size * cmap_entries,
+                     (png_const_bytep)display->colormap +
+                        sample_size * PNG_RGB_INDEX(r,g,b),
+                     sample_size) != 0)
+                  {
+                     /* The background color must be added. */
+                     background_index = cmap_entries++;
+
+                     /* Add 27 r,g,b entries each with created by composing with
+                      * the background at alpha 0.5.
+                      */
+                     for (r=0; r<256; r = (r << 1) | 0x7f)
+                     {
+                        for (g=0; g<256; g = (g << 1) | 0x7f)
+                        {
+                           /* This generates components with the values 0, 127
+                            * and 255
+                            */
+                           for (b=0; b<256; b = (b << 1) | 0x7f)
+                              png_create_colormap_entry(display, cmap_entries++,
+                                 png_colormap_compose(display, r, P_sRGB, 128,
+                                    back_r, output_encoding),
+                                 png_colormap_compose(display, g, P_sRGB, 128,
+                                    back_g, output_encoding),
+                                 png_colormap_compose(display, b, P_sRGB, 128,
+                                    back_b, output_encoding),
+                                 0/*unused*/, output_encoding);
+                        }
+                     }
+
+                     expand_tRNS = 1;
+                     output_processing = PNG_CMAP_RGB_ALPHA;
+                  }
+
+                  else /* background color is in the standard color-map */
+                  {
+                     png_color_16 c;
+
+                     c.index = 0; /*unused*/
+                     c.red = (png_uint_16)back_r;
+                     c.gray = c.green = (png_uint_16)back_g;
+                     c.blue = (png_uint_16)back_b;
+
+                     png_set_background_fixed(png_ptr, &c,
+                        PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
+                        0/*gamma: not used*/);
+
+                     output_processing = PNG_CMAP_RGB;
+                  }
+               }
+            }
+
+            else /* no alpha or transparency in the input */
+            {
+               /* Alpha in the output is irrelevant, simply map the opaque input
+                * pixels to the 6x6x6 color-map.
+                */
+               if (PNG_RGB_COLORMAP_ENTRIES > image->colormap_entries)
+                  png_error(png_ptr, "rgb color-map: too few entries");
+
+               cmap_entries = make_rgb_colormap(display);
+               output_processing = PNG_CMAP_RGB;
+            }
+         }
+         break;
+
+      case PNG_COLOR_TYPE_PALETTE:
+         /* It's already got a color-map.  It may be necessary to eliminate the
+          * tRNS entries though.
+          */
+         {
+            unsigned int num_trans = png_ptr->num_trans;
+            png_const_bytep trans = num_trans > 0 ? png_ptr->trans_alpha : NULL;
+            png_const_colorp colormap = png_ptr->palette;
+            const int do_background = trans != NULL &&
+               (output_format & PNG_FORMAT_FLAG_ALPHA) == 0;
+            unsigned int i;
+
+            /* Just in case: */
+            if (trans == NULL)
+               num_trans = 0;
+
+            output_processing = PNG_CMAP_NONE;
+            data_encoding = P_FILE; /* Don't change from color-map indices */
+            cmap_entries = png_ptr->num_palette;
+            if (cmap_entries > 256)
+               cmap_entries = 256;
+
+            if (cmap_entries > image->colormap_entries)
+               png_error(png_ptr, "palette color-map: too few entries");
+
+            for (i=0; i < cmap_entries; ++i)
+            {
+               if (do_background != 0 && i < num_trans && trans[i] < 255)
+               {
+                  if (trans[i] == 0)
+                     png_create_colormap_entry(display, i, back_r, back_g,
+                        back_b, 0, output_encoding);
+
+                  else
+                  {
+                     /* Must compose the PNG file color in the color-map entry
+                      * on the sRGB color in 'back'.
+                      */
+                     png_create_colormap_entry(display, i,
+                        png_colormap_compose(display, colormap[i].red, P_FILE,
+                           trans[i], back_r, output_encoding),
+                        png_colormap_compose(display, colormap[i].green, P_FILE,
+                           trans[i], back_g, output_encoding),
+                        png_colormap_compose(display, colormap[i].blue, P_FILE,
+                           trans[i], back_b, output_encoding),
+                        output_encoding == P_LINEAR ? trans[i] * 257U :
+                           trans[i],
+                        output_encoding);
+                  }
+               }
+
+               else
+                  png_create_colormap_entry(display, i, colormap[i].red,
+                     colormap[i].green, colormap[i].blue,
+                     i < num_trans ? trans[i] : 255U, P_FILE/*8-bit*/);
+            }
+
+            /* The PNG data may have indices packed in fewer than 8 bits, it
+             * must be expanded if so.
+             */
+            if (png_ptr->bit_depth < 8)
+               png_set_packing(png_ptr);
+         }
+         break;
+
+      default:
+         png_error(png_ptr, "invalid PNG color type");
+         /*NOT REACHED*/
+         break;
+   }
+
+   /* Now deal with the output processing */
+   if (expand_tRNS != 0 && png_ptr->num_trans > 0 &&
+       (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) == 0)
+      png_set_tRNS_to_alpha(png_ptr);
+
+   switch (data_encoding)
+   {
+      default:
+         png_error(png_ptr, "bad data option (internal error)");
+         break;
+
+      case P_sRGB:
+         /* Change to 8-bit sRGB */
+         png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, PNG_GAMMA_sRGB);
+         /* FALL THROUGH */
+
+      case P_FILE:
+         if (png_ptr->bit_depth > 8)
+            png_set_scale_16(png_ptr);
+         break;
+   }
+
+   if (cmap_entries > 256 || cmap_entries > image->colormap_entries)
+      png_error(png_ptr, "color map overflow (BAD internal error)");
+
+   image->colormap_entries = cmap_entries;
+
+   /* Double check using the recorded background index */
+   switch (output_processing)
+   {
+      case PNG_CMAP_NONE:
+         if (background_index != PNG_CMAP_NONE_BACKGROUND)
+            goto bad_background;
+         break;
+
+      case PNG_CMAP_GA:
+         if (background_index != PNG_CMAP_GA_BACKGROUND)
+            goto bad_background;
+         break;
+
+      case PNG_CMAP_TRANS:
+         if (background_index >= cmap_entries ||
+            background_index != PNG_CMAP_TRANS_BACKGROUND)
+            goto bad_background;
+         break;
+
+      case PNG_CMAP_RGB:
+         if (background_index != PNG_CMAP_RGB_BACKGROUND)
+            goto bad_background;
+         break;
+
+      case PNG_CMAP_RGB_ALPHA:
+         if (background_index != PNG_CMAP_RGB_ALPHA_BACKGROUND)
+            goto bad_background;
+         break;
+
+      default:
+         png_error(png_ptr, "bad processing option (internal error)");
+
+      bad_background:
+         png_error(png_ptr, "bad background index (internal error)");
+   }
+
+   display->colormap_processing = output_processing;
+
+   return 1/*ok*/;
+}
+
+/* The final part of the color-map read called from png_image_finish_read. */
+static int
+png_image_read_and_map(png_voidp argument)
+{
+   png_image_read_control *display = png_voidcast(png_image_read_control*,
+      argument);
+   png_imagep image = display->image;
+   png_structrp png_ptr = image->opaque->png_ptr;
+   int passes;
+
+   /* Called when the libpng data must be transformed into the color-mapped
+    * form.  There is a local row buffer in display->local and this routine must
+    * do the interlace handling.
+    */
+   switch (png_ptr->interlaced)
+   {
+      case PNG_INTERLACE_NONE:
+         passes = 1;
+         break;
+
+      case PNG_INTERLACE_ADAM7:
+         passes = PNG_INTERLACE_ADAM7_PASSES;
+         break;
+
+      default:
+         png_error(png_ptr, "unknown interlace type");
+   }
+
+   {
+      png_uint_32  height = image->height;
+      png_uint_32  width = image->width;
+      int          proc = display->colormap_processing;
+      png_bytep    first_row = png_voidcast(png_bytep, display->first_row);
+      ptrdiff_t    step_row = display->row_bytes;
+      int pass;
+
+      for (pass = 0; pass < passes; ++pass)
+      {
+         unsigned int     startx, stepx, stepy;
+         png_uint_32      y;
+
+         if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
+         {
+            /* The row may be empty for a short image: */
+            if (PNG_PASS_COLS(width, pass) == 0)
+               continue;
+
+            startx = PNG_PASS_START_COL(pass);
+            stepx = PNG_PASS_COL_OFFSET(pass);
+            y = PNG_PASS_START_ROW(pass);
+            stepy = PNG_PASS_ROW_OFFSET(pass);
+         }
+
+         else
+         {
+            y = 0;
+            startx = 0;
+            stepx = stepy = 1;
+         }
+
+         for (; y<height; y += stepy)
+         {
+            png_bytep inrow = png_voidcast(png_bytep, display->local_row);
+            png_bytep outrow = first_row + y * step_row;
+            png_const_bytep end_row = outrow + width;
+
+            /* Read read the libpng data into the temporary buffer. */
+            png_read_row(png_ptr, inrow, NULL);
+
+            /* Now process the row according to the processing option, note
+             * that the caller verifies that the format of the libpng output
+             * data is as required.
+             */
+            outrow += startx;
+            switch (proc)
+            {
+               case PNG_CMAP_GA:
+                  for (; outrow < end_row; outrow += stepx)
+                  {
+                     /* The data is always in the PNG order */
+                     unsigned int gray = *inrow++;
+                     unsigned int alpha = *inrow++;
+                     unsigned int entry;
+
+                     /* NOTE: this code is copied as a comment in
+                      * make_ga_colormap above.  Please update the
+                      * comment if you change this code!
+                      */
+                     if (alpha > 229) /* opaque */
+                     {
+                        entry = (231 * gray + 128) >> 8;
+                     }
+                     else if (alpha < 26) /* transparent */
+                     {
+                        entry = 231;
+                     }
+                     else /* partially opaque */
+                     {
+                        entry = 226 + 6 * PNG_DIV51(alpha) + PNG_DIV51(gray);
+                     }
+
+                     *outrow = (png_byte)entry;
+                  }
+                  break;
+
+               case PNG_CMAP_TRANS:
+                  for (; outrow < end_row; outrow += stepx)
+                  {
+                     png_byte gray = *inrow++;
+                     png_byte alpha = *inrow++;
+
+                     if (alpha == 0)
+                        *outrow = PNG_CMAP_TRANS_BACKGROUND;
+
+                     else if (gray != PNG_CMAP_TRANS_BACKGROUND)
+                        *outrow = gray;
+
+                     else
+                        *outrow = (png_byte)(PNG_CMAP_TRANS_BACKGROUND+1);
+                  }
+                  break;
+
+               case PNG_CMAP_RGB:
+                  for (; outrow < end_row; outrow += stepx)
+                  {
+                     *outrow = PNG_RGB_INDEX(inrow[0], inrow[1], inrow[2]);
+                     inrow += 3;
+                  }
+                  break;
+
+               case PNG_CMAP_RGB_ALPHA:
+                  for (; outrow < end_row; outrow += stepx)
+                  {
+                     unsigned int alpha = inrow[3];
+
+                     /* Because the alpha entries only hold alpha==0.5 values
+                      * split the processing at alpha==0.25 (64) and 0.75
+                      * (196).
+                      */
+
+                     if (alpha >= 196)
+                        *outrow = PNG_RGB_INDEX(inrow[0], inrow[1],
+                           inrow[2]);
+
+                     else if (alpha < 64)
+                        *outrow = PNG_CMAP_RGB_ALPHA_BACKGROUND;
+
+                     else
+                     {
+                        /* Likewise there are three entries for each of r, g
+                         * and b.  We could select the entry by popcount on
+                         * the top two bits on those architectures that
+                         * support it, this is what the code below does,
+                         * crudely.
+                         */
+                        unsigned int back_i = PNG_CMAP_RGB_ALPHA_BACKGROUND+1;
+
+                        /* Here are how the values map:
+                         *
+                         * 0x00 .. 0x3f -> 0
+                         * 0x40 .. 0xbf -> 1
+                         * 0xc0 .. 0xff -> 2
+                         *
+                         * So, as above with the explicit alpha checks, the
+                         * breakpoints are at 64 and 196.
+                         */
+                        if (inrow[0] & 0x80) back_i += 9; /* red */
+                        if (inrow[0] & 0x40) back_i += 9;
+                        if (inrow[0] & 0x80) back_i += 3; /* green */
+                        if (inrow[0] & 0x40) back_i += 3;
+                        if (inrow[0] & 0x80) back_i += 1; /* blue */
+                        if (inrow[0] & 0x40) back_i += 1;
+
+                        *outrow = (png_byte)back_i;
+                     }
+
+                     inrow += 4;
+                  }
+                  break;
+
+               default:
+                  break;
+            }
+         }
+      }
+   }
+
+   return 1;
+}
+
+static int
+png_image_read_colormapped(png_voidp argument)
+{
+   png_image_read_control *display = png_voidcast(png_image_read_control*,
+      argument);
+   png_imagep image = display->image;
+   png_controlp control = image->opaque;
+   png_structrp png_ptr = control->png_ptr;
+   png_inforp info_ptr = control->info_ptr;
+
+   int passes = 0; /* As a flag */
+
+   PNG_SKIP_CHUNKS(png_ptr);
+
+   /* Update the 'info' structure and make sure the result is as required; first
+    * make sure to turn on the interlace handling if it will be required
+    * (because it can't be turned on *after* the call to png_read_update_info!)
+    */
+   if (display->colormap_processing == PNG_CMAP_NONE)
+      passes = png_set_interlace_handling(png_ptr);
+
+   png_read_update_info(png_ptr, info_ptr);
+
+   /* The expected output can be deduced from the colormap_processing option. */
+   switch (display->colormap_processing)
+   {
+      case PNG_CMAP_NONE:
+         /* Output must be one channel and one byte per pixel, the output
+          * encoding can be anything.
+          */
+         if ((info_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
+            info_ptr->color_type == PNG_COLOR_TYPE_GRAY) &&
+            info_ptr->bit_depth == 8)
+            break;
+
+         goto bad_output;
+
+      case PNG_CMAP_TRANS:
+      case PNG_CMAP_GA:
+         /* Output must be two channels and the 'G' one must be sRGB, the latter
+          * can be checked with an exact number because it should have been set
+          * to this number above!
+          */
+         if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA &&
+            info_ptr->bit_depth == 8 &&
+            png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
+            image->colormap_entries == 256)
+            break;
+
+         goto bad_output;
+
+      case PNG_CMAP_RGB:
+         /* Output must be 8-bit sRGB encoded RGB */
+         if (info_ptr->color_type == PNG_COLOR_TYPE_RGB &&
+            info_ptr->bit_depth == 8 &&
+            png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
+            image->colormap_entries == 216)
+            break;
+
+         goto bad_output;
+
+      case PNG_CMAP_RGB_ALPHA:
+         /* Output must be 8-bit sRGB encoded RGBA */
+         if (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
+            info_ptr->bit_depth == 8 &&
+            png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
+            image->colormap_entries == 244 /* 216 + 1 + 27 */)
+            break;
+
+         /* goto bad_output; */
+         /* FALL THROUGH */
+
+      default:
+      bad_output:
+         png_error(png_ptr, "bad color-map processing (internal error)");
+   }
+
+   /* Now read the rows.  Do this here if it is possible to read directly into
+    * the output buffer, otherwise allocate a local row buffer of the maximum
+    * size libpng requires and call the relevant processing routine safely.
+    */
+   {
+      png_voidp first_row = display->buffer;
+      ptrdiff_t row_bytes = display->row_stride;
+
+      /* The following expression is designed to work correctly whether it gives
+       * a signed or an unsigned result.
+       */
+      if (row_bytes < 0)
+      {
+         char *ptr = png_voidcast(char*, first_row);
+         ptr += (image->height-1) * (-row_bytes);
+         first_row = png_voidcast(png_voidp, ptr);
+      }
+
+      display->first_row = first_row;
+      display->row_bytes = row_bytes;
+   }
+
+   if (passes == 0)
+   {
+      int result;
+      png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
+
+      display->local_row = row;
+      result = png_safe_execute(image, png_image_read_and_map, display);
+      display->local_row = NULL;
+      png_free(png_ptr, row);
+
+      return result;
+   }
+
+   else
+   {
+      png_alloc_size_t row_bytes = display->row_bytes;
+
+      while (--passes >= 0)
+      {
+         png_uint_32      y = image->height;
+         png_bytep        row = png_voidcast(png_bytep, display->first_row);
+
+         while (y-- > 0)
+         {
+            png_read_row(png_ptr, row, NULL);
+            row += row_bytes;
+         }
+      }
+
+      return 1;
+   }
+}
+
+/* Just the row reading part of png_image_read. */
+static int
+png_image_read_composite(png_voidp argument)
+{
+   png_image_read_control *display = png_voidcast(png_image_read_control*,
+      argument);
+   png_imagep image = display->image;
+   png_structrp png_ptr = image->opaque->png_ptr;
+   int passes;
+
+   switch (png_ptr->interlaced)
+   {
+      case PNG_INTERLACE_NONE:
+         passes = 1;
+         break;
+
+      case PNG_INTERLACE_ADAM7:
+         passes = PNG_INTERLACE_ADAM7_PASSES;
+         break;
+
+      default:
+         png_error(png_ptr, "unknown interlace type");
+   }
+
+   {
+      png_uint_32  height = image->height;
+      png_uint_32  width = image->width;
+      ptrdiff_t    step_row = display->row_bytes;
+      unsigned int channels =
+          (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1;
+      int pass;
+
+      for (pass = 0; pass < passes; ++pass)
+      {
+         unsigned int     startx, stepx, stepy;
+         png_uint_32      y;
+
+         if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
+         {
+            /* The row may be empty for a short image: */
+            if (PNG_PASS_COLS(width, pass) == 0)
+               continue;
+
+            startx = PNG_PASS_START_COL(pass) * channels;
+            stepx = PNG_PASS_COL_OFFSET(pass) * channels;
+            y = PNG_PASS_START_ROW(pass);
+            stepy = PNG_PASS_ROW_OFFSET(pass);
+         }
+
+         else
+         {
+            y = 0;
+            startx = 0;
+            stepx = channels;
+            stepy = 1;
+         }
+
+         for (; y<height; y += stepy)
+         {
+            png_bytep inrow = png_voidcast(png_bytep, display->local_row);
+            png_bytep outrow;
+            png_const_bytep end_row;
+
+            /* Read the row, which is packed: */
+            png_read_row(png_ptr, inrow, NULL);
+
+            outrow = png_voidcast(png_bytep, display->first_row);
+            outrow += y * step_row;
+            end_row = outrow + width * channels;
+
+            /* Now do the composition on each pixel in this row. */
+            outrow += startx;
+            for (; outrow < end_row; outrow += stepx)
+            {
+               png_byte alpha = inrow[channels];
+
+               if (alpha > 0) /* else no change to the output */
+               {
+                  unsigned int c;
+
+                  for (c=0; c<channels; ++c)
+                  {
+                     png_uint_32 component = inrow[c];
+
+                     if (alpha < 255) /* else just use component */
+                     {
+                        /* This is PNG_OPTIMIZED_ALPHA, the component value
+                         * is a linear 8-bit value.  Combine this with the
+                         * current outrow[c] value which is sRGB encoded.
+                         * Arithmetic here is 16-bits to preserve the output
+                         * values correctly.
+                         */
+                        component *= 257*255; /* =65535 */
+                        component += (255-alpha)*png_sRGB_table[outrow[c]];
+
+                        /* So 'component' is scaled by 255*65535 and is
+                         * therefore appropriate for the sRGB to linear
+                         * conversion table.
+                         */
+                        component = PNG_sRGB_FROM_LINEAR(component);
+                     }
+
+                     outrow[c] = (png_byte)component;
+                  }
+               }
+
+               inrow += channels+1; /* components and alpha channel */
+            }
+         }
+      }
+   }
+
+   return 1;
+}
+
+/* The do_local_background case; called when all the following transforms are to
+ * be done:
+ *
+ * PNG_RGB_TO_GRAY
+ * PNG_COMPOSITE
+ * PNG_GAMMA
+ *
+ * This is a work-around for the fact that both the PNG_RGB_TO_GRAY and
+ * PNG_COMPOSITE code performs gamma correction, so we get double gamma
+ * correction.  The fix-up is to prevent the PNG_COMPOSITE operation from
+ * happening inside libpng, so this routine sees an 8 or 16-bit gray+alpha
+ * row and handles the removal or pre-multiplication of the alpha channel.
+ */
+static int
+png_image_read_background(png_voidp argument)
+{
+   png_image_read_control *display = png_voidcast(png_image_read_control*,
+      argument);
+   png_imagep image = display->image;
+   png_structrp png_ptr = image->opaque->png_ptr;
+   png_inforp info_ptr = image->opaque->info_ptr;
+   png_uint_32 height = image->height;
+   png_uint_32 width = image->width;
+   int pass, passes;
+
+   /* Double check the convoluted logic below.  We expect to get here with
+    * libpng doing rgb to gray and gamma correction but background processing
+    * left to the png_image_read_background function.  The rows libpng produce
+    * might be 8 or 16-bit but should always have two channels; gray plus alpha.
+    */
+   if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
+      png_error(png_ptr, "lost rgb to gray");
+
+   if ((png_ptr->transformations & PNG_COMPOSE) != 0)
+      png_error(png_ptr, "unexpected compose");
+
+   if (png_get_channels(png_ptr, info_ptr) != 2)
+      png_error(png_ptr, "lost/gained channels");
+
+   /* Expect the 8-bit case to always remove the alpha channel */
+   if ((image->format & PNG_FORMAT_FLAG_LINEAR) == 0 &&
+      (image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
+      png_error(png_ptr, "unexpected 8-bit transformation");
+
+   switch (png_ptr->interlaced)
+   {
+      case PNG_INTERLACE_NONE:
+         passes = 1;
+         break;
+
+      case PNG_INTERLACE_ADAM7:
+         passes = PNG_INTERLACE_ADAM7_PASSES;
+         break;
+
+      default:
+         png_error(png_ptr, "unknown interlace type");
+   }
+
+   /* Use direct access to info_ptr here because otherwise the simplified API
+    * would require PNG_EASY_ACCESS_SUPPORTED (just for this.)  Note this is
+    * checking the value after libpng expansions, not the original value in the
+    * PNG.
+    */
+   switch (info_ptr->bit_depth)
+   {
+      default:
+         png_error(png_ptr, "unexpected bit depth");
+         break;
+
+      case 8:
+         /* 8-bit sRGB gray values with an alpha channel; the alpha channel is
+          * to be removed by composing on a background: either the row if
+          * display->background is NULL or display->background->green if not.
+          * Unlike the code above ALPHA_OPTIMIZED has *not* been done.
+          */
+         {
+            png_bytep first_row = png_voidcast(png_bytep, display->first_row);
+            ptrdiff_t step_row = display->row_bytes;
+
+            for (pass = 0; pass < passes; ++pass)
+            {
+               png_bytep        row = png_voidcast(png_bytep,
+                                                   display->first_row);
+               unsigned int     startx, stepx, stepy;
+               png_uint_32      y;
+
+               if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
+               {
+                  /* The row may be empty for a short image: */
+                  if (PNG_PASS_COLS(width, pass) == 0)
+                     continue;
+
+                  startx = PNG_PASS_START_COL(pass);
+                  stepx = PNG_PASS_COL_OFFSET(pass);
+                  y = PNG_PASS_START_ROW(pass);
+                  stepy = PNG_PASS_ROW_OFFSET(pass);
+               }
+
+               else
+               {
+                  y = 0;
+                  startx = 0;
+                  stepx = stepy = 1;
+               }
+
+               if (display->background == NULL)
+               {
+                  for (; y<height; y += stepy)
+                  {
+                     png_bytep inrow = png_voidcast(png_bytep,
+                        display->local_row);
+                     png_bytep outrow = first_row + y * step_row;
+                     png_const_bytep end_row = outrow + width;
+
+                     /* Read the row, which is packed: */
+                     png_read_row(png_ptr, inrow, NULL);
+
+                     /* Now do the composition on each pixel in this row. */
+                     outrow += startx;
+                     for (; outrow < end_row; outrow += stepx)
+                     {
+                        png_byte alpha = inrow[1];
+
+                        if (alpha > 0) /* else no change to the output */
+                        {
+                           png_uint_32 component = inrow[0];
+
+                           if (alpha < 255) /* else just use component */
+                           {
+                              /* Since PNG_OPTIMIZED_ALPHA was not set it is
+                               * necessary to invert the sRGB transfer
+                               * function and multiply the alpha out.
+                               */
+                              component = png_sRGB_table[component] * alpha;
+                              component += png_sRGB_table[outrow[0]] *
+                                 (255-alpha);
+                              component = PNG_sRGB_FROM_LINEAR(component);
+                           }
+
+                           outrow[0] = (png_byte)component;
+                        }
+
+                        inrow += 2; /* gray and alpha channel */
+                     }
+                  }
+               }
+
+               else /* constant background value */
+               {
+                  png_byte background8 = display->background->green;
+                  png_uint_16 background = png_sRGB_table[background8];
+
+                  for (; y<height; y += stepy)
+                  {
+                     png_bytep inrow = png_voidcast(png_bytep,
+                        display->local_row);
+                     png_bytep outrow = first_row + y * step_row;
+                     png_const_bytep end_row = outrow + width;
+
+                     /* Read the row, which is packed: */
+                     png_read_row(png_ptr, inrow, NULL);
+
+                     /* Now do the composition on each pixel in this row. */
+                     outrow += startx;
+                     for (; outrow < end_row; outrow += stepx)
+                     {
+                        png_byte alpha = inrow[1];
+
+                        if (alpha > 0) /* else use background */
+                        {
+                           png_uint_32 component = inrow[0];
+
+                           if (alpha < 255) /* else just use component */
+                           {
+                              component = png_sRGB_table[component] * alpha;
+                              component += background * (255-alpha);
+                              component = PNG_sRGB_FROM_LINEAR(component);
+                           }
+
+                           outrow[0] = (png_byte)component;
+                        }
+
+                        else
+                           outrow[0] = background8;
+
+                        inrow += 2; /* gray and alpha channel */
+                     }
+
+                     row += display->row_bytes;
+                  }
+               }
+            }
+         }
+         break;
+
+      case 16:
+         /* 16-bit linear with pre-multiplied alpha; the pre-multiplication must
+          * still be done and, maybe, the alpha channel removed.  This code also
+          * handles the alpha-first option.
+          */
+         {
+            png_uint_16p first_row = png_voidcast(png_uint_16p,
+               display->first_row);
+            /* The division by two is safe because the caller passed in a
+             * stride which was multiplied by 2 (below) to get row_bytes.
+             */
+            ptrdiff_t    step_row = display->row_bytes / 2;
+            int preserve_alpha = (image->format & PNG_FORMAT_FLAG_ALPHA) != 0;
+            unsigned int outchannels = 1+preserve_alpha;
+            int swap_alpha = 0;
+
+#           ifdef PNG_SIMPLIFIED_READ_AFIRST_SUPPORTED
+               if (preserve_alpha != 0 &&
+                   (image->format & PNG_FORMAT_FLAG_AFIRST) != 0)
+                  swap_alpha = 1;
+#           endif
+
+            for (pass = 0; pass < passes; ++pass)
+            {
+               unsigned int     startx, stepx, stepy;
+               png_uint_32      y;
+
+               /* The 'x' start and step are adjusted to output components here.
+                */
+               if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
+               {
+                  /* The row may be empty for a short image: */
+                  if (PNG_PASS_COLS(width, pass) == 0)
+                     continue;
+
+                  startx = PNG_PASS_START_COL(pass) * outchannels;
+                  stepx = PNG_PASS_COL_OFFSET(pass) * outchannels;
+                  y = PNG_PASS_START_ROW(pass);
+                  stepy = PNG_PASS_ROW_OFFSET(pass);
+               }
+
+               else
+               {
+                  y = 0;
+                  startx = 0;
+                  stepx = outchannels;
+                  stepy = 1;
+               }
+
+               for (; y<height; y += stepy)
+               {
+                  png_const_uint_16p inrow;
+                  png_uint_16p outrow = first_row + y*step_row;
+                  png_uint_16p end_row = outrow + width * outchannels;
+
+                  /* Read the row, which is packed: */
+                  png_read_row(png_ptr, png_voidcast(png_bytep,
+                     display->local_row), NULL);
+                  inrow = png_voidcast(png_const_uint_16p, display->local_row);
+
+                  /* Now do the pre-multiplication on each pixel in this row.
+                   */
+                  outrow += startx;
+                  for (; outrow < end_row; outrow += stepx)
+                  {
+                     png_uint_32 component = inrow[0];
+                     png_uint_16 alpha = inrow[1];
+
+                     if (alpha > 0) /* else 0 */
+                     {
+                        if (alpha < 65535) /* else just use component */
+                        {
+                           component *= alpha;
+                           component += 32767;
+                           component /= 65535;
+                        }
+                     }
+
+                     else
+                        component = 0;
+
+                     outrow[swap_alpha] = (png_uint_16)component;
+                     if (preserve_alpha != 0)
+                        outrow[1 ^ swap_alpha] = alpha;
+
+                     inrow += 2; /* components and alpha channel */
+                  }
+               }
+            }
+         }
+         break;
+   }
+
+   return 1;
+}
+
+/* The guts of png_image_finish_read as a png_safe_execute callback. */
+static int
+png_image_read_direct(png_voidp argument)
+{
+   png_image_read_control *display = png_voidcast(png_image_read_control*,
+      argument);
+   png_imagep image = display->image;
+   png_structrp png_ptr = image->opaque->png_ptr;
+   png_inforp info_ptr = image->opaque->info_ptr;
+
+   png_uint_32 format = image->format;
+   int linear = (format & PNG_FORMAT_FLAG_LINEAR) != 0;
+   int do_local_compose = 0;
+   int do_local_background = 0; /* to avoid double gamma correction bug */
+   int passes = 0;
+
+   /* Add transforms to ensure the correct output format is produced then check
+    * that the required implementation support is there.  Always expand; always
+    * need 8 bits minimum, no palette and expanded tRNS.
+    */
+   png_set_expand(png_ptr);
+
+   /* Now check the format to see if it was modified. */
+   {
+      png_uint_32 base_format = png_image_format(png_ptr) &
+         ~PNG_FORMAT_FLAG_COLORMAP /* removed by png_set_expand */;
+      png_uint_32 change = format ^ base_format;
+      png_fixed_point output_gamma;
+      int mode; /* alpha mode */
+
+      /* Do this first so that we have a record if rgb to gray is happening. */
+      if ((change & PNG_FORMAT_FLAG_COLOR) != 0)
+      {
+         /* gray<->color transformation required. */
+         if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
+            png_set_gray_to_rgb(png_ptr);
+
+         else
+         {
+            /* libpng can't do both rgb to gray and
+             * background/pre-multiplication if there is also significant gamma
+             * correction, because both operations require linear colors and
+             * the code only supports one transform doing the gamma correction.
+             * Handle this by doing the pre-multiplication or background
+             * operation in this code, if necessary.
+             *
+             * TODO: fix this by rewriting pngrtran.c (!)
+             *
+             * For the moment (given that fixing this in pngrtran.c is an
+             * enormous change) 'do_local_background' is used to indicate that
+             * the problem exists.
+             */
+            if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
+               do_local_background = 1/*maybe*/;
+
+            png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE,
+               PNG_RGB_TO_GRAY_DEFAULT, PNG_RGB_TO_GRAY_DEFAULT);
+         }
+
+         change &= ~PNG_FORMAT_FLAG_COLOR;
+      }
+
+      /* Set the gamma appropriately, linear for 16-bit input, sRGB otherwise.
+       */
+      {
+         png_fixed_point input_gamma_default;
+
+         if ((base_format & PNG_FORMAT_FLAG_LINEAR) != 0 &&
+             (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
+            input_gamma_default = PNG_GAMMA_LINEAR;
+         else
+            input_gamma_default = PNG_DEFAULT_sRGB;
+
+         /* Call png_set_alpha_mode to set the default for the input gamma; the
+          * output gamma is set by a second call below.
+          */
+         png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, input_gamma_default);
+      }
+
+      if (linear != 0)
+      {
+         /* If there *is* an alpha channel in the input it must be multiplied
+          * out; use PNG_ALPHA_STANDARD, otherwise just use PNG_ALPHA_PNG.
+          */
+         if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
+            mode = PNG_ALPHA_STANDARD; /* associated alpha */
+
+         else
+            mode = PNG_ALPHA_PNG;
+
+         output_gamma = PNG_GAMMA_LINEAR;
+      }
+
+      else
+      {
+         mode = PNG_ALPHA_PNG;
+         output_gamma = PNG_DEFAULT_sRGB;
+      }
+
+      /* If 'do_local_background' is set check for the presence of gamma
+       * correction; this is part of the work-round for the libpng bug
+       * described above.
+       *
+       * TODO: fix libpng and remove this.
+       */
+      if (do_local_background != 0)
+      {
+         png_fixed_point gtest;
+
+         /* This is 'png_gamma_threshold' from pngrtran.c; the test used for
+          * gamma correction, the screen gamma hasn't been set on png_struct
+          * yet; it's set below.  png_struct::gamma, however, is set to the
+          * final value.
+          */
+         if (png_muldiv(&gtest, output_gamma, png_ptr->colorspace.gamma,
+               PNG_FP_1) != 0 && png_gamma_significant(gtest) == 0)
+            do_local_background = 0;
+
+         else if (mode == PNG_ALPHA_STANDARD)
+         {
+            do_local_background = 2/*required*/;
+            mode = PNG_ALPHA_PNG; /* prevent libpng doing it */
+         }
+
+         /* else leave as 1 for the checks below */
+      }
+
+      /* If the bit-depth changes then handle that here. */
+      if ((change & PNG_FORMAT_FLAG_LINEAR) != 0)
+      {
+         if (linear != 0 /*16-bit output*/)
+            png_set_expand_16(png_ptr);
+
+         else /* 8-bit output */
+            png_set_scale_16(png_ptr);
+
+         change &= ~PNG_FORMAT_FLAG_LINEAR;
+      }
+
+      /* Now the background/alpha channel changes. */
+      if ((change & PNG_FORMAT_FLAG_ALPHA) != 0)
+      {
+         /* Removing an alpha channel requires composition for the 8-bit
+          * formats; for the 16-bit it is already done, above, by the
+          * pre-multiplication and the channel just needs to be stripped.
+          */
+         if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
+         {
+            /* If RGB->gray is happening the alpha channel must be left and the
+             * operation completed locally.
+             *
+             * TODO: fix libpng and remove this.
+             */
+            if (do_local_background != 0)
+               do_local_background = 2/*required*/;
+
+            /* 16-bit output: just remove the channel */
+            else if (linear != 0) /* compose on black (well, pre-multiply) */
+               png_set_strip_alpha(png_ptr);
+
+            /* 8-bit output: do an appropriate compose */
+            else if (display->background != NULL)
+            {
+               png_color_16 c;
+
+               c.index = 0; /*unused*/
+               c.red = display->background->red;
+               c.green = display->background->green;
+               c.blue = display->background->blue;
+               c.gray = display->background->green;
+
+               /* This is always an 8-bit sRGB value, using the 'green' channel
+                * for gray is much better than calculating the luminance here;
+                * we can get off-by-one errors in that calculation relative to
+                * the app expectations and that will show up in transparent
+                * pixels.
+                */
+               png_set_background_fixed(png_ptr, &c,
+                  PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
+                  0/*gamma: not used*/);
+            }
+
+            else /* compose on row: implemented below. */
+            {
+               do_local_compose = 1;
+               /* This leaves the alpha channel in the output, so it has to be
+                * removed by the code below.  Set the encoding to the 'OPTIMIZE'
+                * one so the code only has to hack on the pixels that require
+                * composition.
+                */
+               mode = PNG_ALPHA_OPTIMIZED;
+            }
+         }
+
+         else /* output needs an alpha channel */
+         {
+            /* This is tricky because it happens before the swap operation has
+             * been accomplished; however, the swap does *not* swap the added
+             * alpha channel (weird API), so it must be added in the correct
+             * place.
+             */
+            png_uint_32 filler; /* opaque filler */
+            int where;
+
+            if (linear != 0)
+               filler = 65535;
+
+            else
+               filler = 255;
+
+#           ifdef PNG_FORMAT_AFIRST_SUPPORTED
+               if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
+               {
+                  where = PNG_FILLER_BEFORE;
+                  change &= ~PNG_FORMAT_FLAG_AFIRST;
+               }
+
+               else
+#           endif
+               where = PNG_FILLER_AFTER;
+
+            png_set_add_alpha(png_ptr, filler, where);
+         }
+
+         /* This stops the (irrelevant) call to swap_alpha below. */
+         change &= ~PNG_FORMAT_FLAG_ALPHA;
+      }
+
+      /* Now set the alpha mode correctly; this is always done, even if there is
+       * no alpha channel in either the input or the output because it correctly
+       * sets the output gamma.
+       */
+      png_set_alpha_mode_fixed(png_ptr, mode, output_gamma);
+
+#     ifdef PNG_FORMAT_BGR_SUPPORTED
+         if ((change & PNG_FORMAT_FLAG_BGR) != 0)
+         {
+            /* Check only the output format; PNG is never BGR; don't do this if
+             * the output is gray, but fix up the 'format' value in that case.
+             */
+            if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
+               png_set_bgr(png_ptr);
+
+            else
+               format &= ~PNG_FORMAT_FLAG_BGR;
+
+            change &= ~PNG_FORMAT_FLAG_BGR;
+         }
+#     endif
+
+#     ifdef PNG_FORMAT_AFIRST_SUPPORTED
+         if ((change & PNG_FORMAT_FLAG_AFIRST) != 0)
+         {
+            /* Only relevant if there is an alpha channel - it's particularly
+             * important to handle this correctly because do_local_compose may
+             * be set above and then libpng will keep the alpha channel for this
+             * code to remove.
+             */
+            if ((format & PNG_FORMAT_FLAG_ALPHA) != 0)
+            {
+               /* Disable this if doing a local background,
+                * TODO: remove this when local background is no longer required.
+                */
+               if (do_local_background != 2)
+                  png_set_swap_alpha(png_ptr);
+            }
+
+            else
+               format &= ~PNG_FORMAT_FLAG_AFIRST;
+
+            change &= ~PNG_FORMAT_FLAG_AFIRST;
+         }
+#     endif
+
+      /* If the *output* is 16-bit then we need to check for a byte-swap on this
+       * architecture.
+       */
+      if (linear != 0)
+      {
+         PNG_CONST png_uint_16 le = 0x0001;
+
+         if ((*(png_const_bytep) & le) != 0)
+            png_set_swap(png_ptr);
+      }
+
+      /* If change is not now 0 some transformation is missing - error out. */
+      if (change != 0)
+         png_error(png_ptr, "png_read_image: unsupported transformation");
+   }
+
+   PNG_SKIP_CHUNKS(png_ptr);
+
+   /* Update the 'info' structure and make sure the result is as required; first
+    * make sure to turn on the interlace handling if it will be required
+    * (because it can't be turned on *after* the call to png_read_update_info!)
+    *
+    * TODO: remove the do_local_background fixup below.
+    */
+   if (do_local_compose == 0 && do_local_background != 2)
+      passes = png_set_interlace_handling(png_ptr);
+
+   png_read_update_info(png_ptr, info_ptr);
+
+   {
+      png_uint_32 info_format = 0;
+
+      if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
+         info_format |= PNG_FORMAT_FLAG_COLOR;
+
+      if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
+      {
+         /* do_local_compose removes this channel below. */
+         if (do_local_compose == 0)
+         {
+            /* do_local_background does the same if required. */
+            if (do_local_background != 2 ||
+               (format & PNG_FORMAT_FLAG_ALPHA) != 0)
+               info_format |= PNG_FORMAT_FLAG_ALPHA;
+         }
+      }
+
+      else if (do_local_compose != 0) /* internal error */
+         png_error(png_ptr, "png_image_read: alpha channel lost");
+
+      if (info_ptr->bit_depth == 16)
+         info_format |= PNG_FORMAT_FLAG_LINEAR;
+
+#     ifdef PNG_FORMAT_BGR_SUPPORTED
+         if ((png_ptr->transformations & PNG_BGR) != 0)
+            info_format |= PNG_FORMAT_FLAG_BGR;
+#     endif
+
+#     ifdef PNG_FORMAT_AFIRST_SUPPORTED
+         if (do_local_background == 2)
+         {
+            if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
+               info_format |= PNG_FORMAT_FLAG_AFIRST;
+         }
+
+         if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0 ||
+            ((png_ptr->transformations & PNG_ADD_ALPHA) != 0 &&
+            (png_ptr->flags & PNG_FLAG_FILLER_AFTER) == 0))
+         {
+            if (do_local_background == 2)
+               png_error(png_ptr, "unexpected alpha swap transformation");
+
+            info_format |= PNG_FORMAT_FLAG_AFIRST;
+         }
+#     endif
+
+      /* This is actually an internal error. */
+      if (info_format != format)
+         png_error(png_ptr, "png_read_image: invalid transformations");
+   }
+
+   /* Now read the rows.  If do_local_compose is set then it is necessary to use
+    * a local row buffer.  The output will be GA, RGBA or BGRA and must be
+    * converted to G, RGB or BGR as appropriate.  The 'local_row' member of the
+    * display acts as a flag.
+    */
+   {
+      png_voidp first_row = display->buffer;
+      ptrdiff_t row_bytes = display->row_stride;
+
+      if (linear != 0)
+         row_bytes *= 2;
+
+      /* The following expression is designed to work correctly whether it gives
+       * a signed or an unsigned result.
+       */
+      if (row_bytes < 0)
+      {
+         char *ptr = png_voidcast(char*, first_row);
+         ptr += (image->height-1) * (-row_bytes);
+         first_row = png_voidcast(png_voidp, ptr);
+      }
+
+      display->first_row = first_row;
+      display->row_bytes = row_bytes;
+   }
+
+   if (do_local_compose != 0)
+   {
+      int result;
+      png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
+
+      display->local_row = row;
+      result = png_safe_execute(image, png_image_read_composite, display);
+      display->local_row = NULL;
+      png_free(png_ptr, row);
+
+      return result;
+   }
+
+   else if (do_local_background == 2)
+   {
+      int result;
+      png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
+
+      display->local_row = row;
+      result = png_safe_execute(image, png_image_read_background, display);
+      display->local_row = NULL;
+      png_free(png_ptr, row);
+
+      return result;
+   }
+
+   else
+   {
+      png_alloc_size_t row_bytes = display->row_bytes;
+
+      while (--passes >= 0)
+      {
+         png_uint_32      y = image->height;
+         png_bytep        row = png_voidcast(png_bytep, display->first_row);
+
+         while (y-- > 0)
+         {
+            png_read_row(png_ptr, row, NULL);
+            row += row_bytes;
+         }
+      }
+
+      return 1;
+   }
 }
-#endif /* PNG_INFO_IMAGE_SUPPORTED */
-#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
-#endif /* PNG_READ_SUPPORTED */
+
+int PNGAPI
+png_image_finish_read(png_imagep image, png_const_colorp background,
+   void *buffer, png_int_32 row_stride, void *colormap)
+{
+   if (image != NULL && image->version == PNG_IMAGE_VERSION)
+   {
+      png_uint_32 check;
+
+      if (row_stride == 0)
+         row_stride = PNG_IMAGE_ROW_STRIDE(*image);
+
+      if (row_stride < 0)
+         check = -row_stride;
+
+      else
+         check = row_stride;
+
+      if (image->opaque != NULL && buffer != NULL &&
+         check >= PNG_IMAGE_ROW_STRIDE(*image))
+      {
+         if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 ||
+            (image->colormap_entries > 0 && colormap != NULL))
+         {
+            int result;
+            png_image_read_control display;
+
+            memset(&display, 0, (sizeof display));
+            display.image = image;
+            display.buffer = buffer;
+            display.row_stride = row_stride;
+            display.colormap = colormap;
+            display.background = background;
+            display.local_row = NULL;
+
+            /* Choose the correct 'end' routine; for the color-map case all the
+             * setup has already been done.
+             */
+            if ((image->format & PNG_FORMAT_FLAG_COLORMAP) != 0)
+               result =
+                  png_safe_execute(image, png_image_read_colormap, &display) &&
+                  png_safe_execute(image, png_image_read_colormapped, &display);
+
+            else
+               result =
+                  png_safe_execute(image, png_image_read_direct, &display);
+
+            png_image_free(image);
+            return result;
+         }
+
+         else
+            return png_image_error(image,
+               "png_image_finish_read[color-map]: no color-map");
+      }
+
+      else
+         return png_image_error(image,
+            "png_image_finish_read: invalid argument");
+   }
+
+   else if (image != NULL)
+      return png_image_error(image,
+         "png_image_finish_read: damaged PNG_IMAGE_VERSION");
+
+   return 0;
+}
+
+#endif /* SIMPLIFIED_READ */
+#endif /* READ */
diff --git a/src/3rdparty/libpng/pngrio.c b/src/3rdparty/libpng/pngrio.c
index e9c381c..bb5c825 100644
--- a/src/3rdparty/libpng/pngrio.c
+++ b/src/3rdparty/libpng/pngrio.c
@@ -1,8 +1,8 @@
 
 /* pngrio.c - functions for data input
  *
- * Last changed in libpng 1.5.0 [January 6, 2011]
- * Copyright (c) 1998-2011 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.17 [March 26, 2015]
+ * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
@@ -26,10 +26,10 @@
  * reads from a file pointer.  Note that this routine sometimes gets called
  * with very small lengths, so you should implement some kind of simple
  * buffering if you are using unbuffered reads.  This should never be asked
- * to read more then 64K on a 16 bit machine.
+ * to read more than 64K on a 16 bit machine.
  */
 void /* PRIVATE */
-png_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
+png_read_data(png_structrp png_ptr, png_bytep data, png_size_t length)
 {
    png_debug1(4, "reading %d bytes", (int)length);
 
@@ -46,7 +46,6 @@ png_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
  * read_data function and use it at run time with png_set_read_fn(), rather
  * than changing the library.
  */
-#  ifndef USE_FAR_KEYWORD
 void PNGCBAPI
 png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
 {
@@ -58,68 +57,11 @@ png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
    /* fread() returns 0 on error, so it is OK to store this in a png_size_t
     * instead of an int, which is what fread() actually returns.
     */
-   check = fread(data, 1, length, (png_FILE_p)png_ptr->io_ptr);
+   check = fread(data, 1, length, png_voidcast(png_FILE_p, png_ptr->io_ptr));
 
    if (check != length)
       png_error(png_ptr, "Read Error");
 }
-#  else
-/* This is the model-independent version. Since the standard I/O library
-   can't handle far buffers in the medium and small models, we have to copy
-   the data.
-*/
-
-#define NEAR_BUF_SIZE 1024
-#define MIN(a,b) (a <= b ? a : b)
-
-static void PNGCBAPI
-png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
-{
-   png_size_t check;
-   png_byte *n_data;
-   png_FILE_p io_ptr;
-
-   if (png_ptr == NULL)
-      return;
-
-   /* Check if data really is near. If so, use usual code. */
-   n_data = (png_byte *)CVT_PTR_NOCHECK(data);
-   io_ptr = (png_FILE_p)CVT_PTR(png_ptr->io_ptr);
-
-   if ((png_bytep)n_data == data)
-   {
-      check = fread(n_data, 1, length, io_ptr);
-   }
-
-   else
-   {
-      png_byte buf[NEAR_BUF_SIZE];
-      png_size_t read, remaining, err;
-      check = 0;
-      remaining = length;
-
-      do
-      {
-         read = MIN(NEAR_BUF_SIZE, remaining);
-         err = fread(buf, 1, read, io_ptr);
-         png_memcpy(data, buf, read); /* copy far buffer to near buffer */
-
-         if (err != read)
-            break;
-
-         else
-            check += err;
-
-         data += read;
-         remaining -= read;
-      }
-      while (remaining != 0);
-   }
-
-   if ((png_uint_32)check != (png_uint_32)length)
-      png_error(png_ptr, "read Error");
-}
-#  endif
 #endif
 
 /* This function allows the application to supply a new input function
@@ -142,7 +84,7 @@ png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
  *                be used.
  */
 void PNGAPI
-png_set_read_fn(png_structp png_ptr, png_voidp io_ptr,
+png_set_read_fn(png_structrp png_ptr, png_voidp io_ptr,
    png_rw_ptr read_data_fn)
 {
    if (png_ptr == NULL)
@@ -160,6 +102,7 @@ png_set_read_fn(png_structp png_ptr, png_voidp io_ptr,
    png_ptr->read_data_fn = read_data_fn;
 #endif
 
+#ifdef PNG_WRITE_SUPPORTED
    /* It is an error to write to a read device */
    if (png_ptr->write_data_fn != NULL)
    {
@@ -168,9 +111,10 @@ png_set_read_fn(png_structp png_ptr, png_voidp io_ptr,
           "Can't set both read_data_fn and write_data_fn in the"
           " same structure");
    }
+#endif
 
 #ifdef PNG_WRITE_FLUSH_SUPPORTED
    png_ptr->output_flush_fn = NULL;
 #endif
 }
-#endif /* PNG_READ_SUPPORTED */
+#endif /* READ */
diff --git a/src/3rdparty/libpng/pngrtran.c b/src/3rdparty/libpng/pngrtran.c
index 5561852..cad7a8d 100644
--- a/src/3rdparty/libpng/pngrtran.c
+++ b/src/3rdparty/libpng/pngrtran.c
@@ -1,8 +1,8 @@
 
 /* pngrtran.c - transforms the data in a row for PNG readers
  *
- * Last changed in libpng 1.5.10 [March 8, 2012]
- * Copyright (c) 1998-2012 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.17 [March 26, 2015]
+ * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
@@ -22,7 +22,7 @@
 
 /* Set the action on getting a CRC error for an ancillary or critical chunk. */
 void PNGAPI
-png_set_crc_action(png_structp png_ptr, int crit_action, int ancil_action)
+png_set_crc_action(png_structrp png_ptr, int crit_action, int ancil_action)
 {
    png_debug(1, "in png_set_crc_action");
 
@@ -88,16 +88,47 @@ png_set_crc_action(png_structp png_ptr, int crit_action, int ancil_action)
    }
 }
 
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
+/* Is it OK to set a transformation now?  Only if png_start_read_image or
+ * png_read_update_info have not been called.  It is not necessary for the IHDR
+ * to have been read in all cases; the need_IHDR parameter allows for this
+ * check too.
+ */
+static int
+png_rtran_ok(png_structrp png_ptr, int need_IHDR)
+{
+   if (png_ptr != NULL)
+   {
+      if ((png_ptr->flags & PNG_FLAG_ROW_INIT) != 0)
+         png_app_error(png_ptr,
+            "invalid after png_start_read_image or png_read_update_info");
+
+      else if (need_IHDR && (png_ptr->mode & PNG_HAVE_IHDR) == 0)
+         png_app_error(png_ptr, "invalid before the PNG header has been read");
+
+      else
+      {
+         /* Turn on failure to initialize correctly for all transforms. */
+         png_ptr->flags |= PNG_FLAG_DETECT_UNINITIALIZED;
+
+         return 1; /* Ok */
+      }
+   }
+
+   return 0; /* no png_error possible! */
+}
+#endif
+
 #ifdef PNG_READ_BACKGROUND_SUPPORTED
 /* Handle alpha and tRNS via a background color */
 void PNGFAPI
-png_set_background_fixed(png_structp png_ptr,
+png_set_background_fixed(png_structrp png_ptr,
     png_const_color_16p background_color, int background_gamma_code,
     int need_expand, png_fixed_point background_gamma)
 {
    png_debug(1, "in png_set_background_fixed");
 
-   if (png_ptr == NULL)
+   if (png_rtran_ok(png_ptr, 0) == 0 || background_color == NULL)
       return;
 
    if (background_gamma_code == PNG_BACKGROUND_GAMMA_UNKNOWN)
@@ -110,11 +141,10 @@ png_set_background_fixed(png_structp png_ptr,
    png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
    png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
 
-   png_memcpy(&(png_ptr->background), background_color,
-      png_sizeof(png_color_16));
+   png_ptr->background = *background_color;
    png_ptr->background_gamma = background_gamma;
    png_ptr->background_gamma_type = (png_byte)(background_gamma_code);
-   if (need_expand)
+   if (need_expand != 0)
       png_ptr->transformations |= PNG_BACKGROUND_EXPAND;
    else
       png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
@@ -122,7 +152,7 @@ png_set_background_fixed(png_structp png_ptr,
 
 #  ifdef PNG_FLOATING_POINT_SUPPORTED
 void PNGAPI
-png_set_background(png_structp png_ptr,
+png_set_background(png_structrp png_ptr,
     png_const_color_16p background_color, int background_gamma_code,
     int need_expand, double background_gamma)
 {
@@ -138,11 +168,11 @@ png_set_background(png_structp png_ptr,
  */
 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
 void PNGAPI
-png_set_scale_16(png_structp png_ptr)
+png_set_scale_16(png_structrp png_ptr)
 {
    png_debug(1, "in png_set_scale_16");
 
-   if (png_ptr == NULL)
+   if (png_rtran_ok(png_ptr, 0) == 0)
       return;
 
    png_ptr->transformations |= PNG_SCALE_16_TO_8;
@@ -152,11 +182,11 @@ png_set_scale_16(png_structp png_ptr)
 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
 /* Chop 16-bit depth files to 8-bit depth */
 void PNGAPI
-png_set_strip_16(png_structp png_ptr)
+png_set_strip_16(png_structrp png_ptr)
 {
    png_debug(1, "in png_set_strip_16");
 
-   if (png_ptr == NULL)
+   if (png_rtran_ok(png_ptr, 0) == 0)
       return;
 
    png_ptr->transformations |= PNG_16_TO_8;
@@ -165,11 +195,11 @@ png_set_strip_16(png_structp png_ptr)
 
 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
 void PNGAPI
-png_set_strip_alpha(png_structp png_ptr)
+png_set_strip_alpha(png_structrp png_ptr)
 {
    png_debug(1, "in png_set_strip_alpha");
 
-   if (png_ptr == NULL)
+   if (png_rtran_ok(png_ptr, 0) == 0)
       return;
 
    png_ptr->transformations |= PNG_STRIP_ALPHA;
@@ -178,7 +208,7 @@ png_set_strip_alpha(png_structp png_ptr)
 
 #if defined(PNG_READ_ALPHA_MODE_SUPPORTED) || defined(PNG_READ_GAMMA_SUPPORTED)
 static png_fixed_point
-translate_gamma_flags(png_structp png_ptr, png_fixed_point output_gamma,
+translate_gamma_flags(png_structrp png_ptr, png_fixed_point output_gamma,
    int is_screen)
 {
    /* Check for flag values.  The main reason for having the old Mac value as a
@@ -194,8 +224,10 @@ translate_gamma_flags(png_structp png_ptr, png_fixed_point output_gamma,
        */
 #     ifdef PNG_READ_sRGB_SUPPORTED
          png_ptr->flags |= PNG_FLAG_ASSUME_sRGB;
+#     else
+         PNG_UNUSED(png_ptr)
 #     endif
-      if (is_screen)
+      if (is_screen != 0)
          output_gamma = PNG_GAMMA_sRGB;
       else
          output_gamma = PNG_GAMMA_sRGB_INVERSE;
@@ -204,7 +236,7 @@ translate_gamma_flags(png_structp png_ptr, png_fixed_point output_gamma,
    else if (output_gamma == PNG_GAMMA_MAC_18 ||
       output_gamma == PNG_FP_1 / PNG_GAMMA_MAC_18)
    {
-      if (is_screen)
+      if (is_screen != 0)
          output_gamma = PNG_GAMMA_MAC_OLD;
       else
          output_gamma = PNG_GAMMA_MAC_INVERSE;
@@ -215,7 +247,7 @@ translate_gamma_flags(png_structp png_ptr, png_fixed_point output_gamma,
 
 #  ifdef PNG_FLOATING_POINT_SUPPORTED
 static png_fixed_point
-convert_gamma_value(png_structp png_ptr, double output_gamma)
+convert_gamma_value(png_structrp png_ptr, double output_gamma)
 {
    /* The following silently ignores cases where fixed point (times 100,000)
     * gamma values are passed to the floating point API.  This is safe and it
@@ -240,7 +272,7 @@ convert_gamma_value(png_structp png_ptr, double output_gamma)
 
 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
 void PNGFAPI
-png_set_alpha_mode_fixed(png_structp png_ptr, int mode,
+png_set_alpha_mode_fixed(png_structrp png_ptr, int mode,
    png_fixed_point output_gamma)
 {
    int compose = 0;
@@ -248,7 +280,7 @@ png_set_alpha_mode_fixed(png_structp png_ptr, int mode,
 
    png_debug(1, "in png_set_alpha_mode");
 
-   if (png_ptr == NULL)
+   if (png_rtran_ok(png_ptr, 0) == 0)
       return;
 
    output_gamma = translate_gamma_flags(png_ptr, output_gamma, 1/*screen*/);
@@ -320,8 +352,11 @@ png_set_alpha_mode_fixed(png_structp png_ptr, int mode,
     * the side effect that the gamma in a second call to png_set_alpha_mode will
     * be ignored.)
     */
-   if (png_ptr->gamma == 0)
-      png_ptr->gamma = file_gamma;
+   if (png_ptr->colorspace.gamma == 0)
+   {
+      png_ptr->colorspace.gamma = file_gamma;
+      png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
+   }
 
    /* But always set the output gamma: */
    png_ptr->screen_gamma = output_gamma;
@@ -329,28 +364,25 @@ png_set_alpha_mode_fixed(png_structp png_ptr, int mode,
    /* Finally, if pre-multiplying, set the background fields to achieve the
     * desired result.
     */
-   if (compose)
+   if (compose != 0)
    {
       /* And obtain alpha pre-multiplication by composing on black: */
-      png_memset(&png_ptr->background, 0, sizeof png_ptr->background);
-      png_ptr->background_gamma = png_ptr->gamma; /* just in case */
+      memset(&png_ptr->background, 0, (sizeof png_ptr->background));
+      png_ptr->background_gamma = png_ptr->colorspace.gamma; /* just in case */
       png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_FILE;
       png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
 
-      if (png_ptr->transformations & PNG_COMPOSE)
+      if ((png_ptr->transformations & PNG_COMPOSE) != 0)
          png_error(png_ptr,
             "conflicting calls to set alpha mode and background");
 
       png_ptr->transformations |= PNG_COMPOSE;
    }
-
-   /* New API, make sure apps call the correct initializers: */
-   png_ptr->flags |= PNG_FLAG_DETECT_UNINITIALIZED;
 }
 
 #  ifdef PNG_FLOATING_POINT_SUPPORTED
 void PNGAPI
-png_set_alpha_mode(png_structp png_ptr, int mode, double output_gamma)
+png_set_alpha_mode(png_structrp png_ptr, int mode, double output_gamma)
 {
    png_set_alpha_mode_fixed(png_ptr, mode, convert_gamma_value(png_ptr,
       output_gamma));
@@ -362,7 +394,7 @@ png_set_alpha_mode(png_structp png_ptr, int mode, double output_gamma)
 /* Dither file to 8-bit.  Supply a palette, the current number
  * of elements in the palette, the maximum number of elements
  * allowed, and a histogram if possible.  If the current number
- * of colors is greater then the maximum number, the palette will be
+ * of colors is greater than the maximum number, the palette will be
  * modified to fit in the maximum number.  "full_quantize" indicates
  * whether we need a quantizing cube set up for RGB images, or if we
  * simply are reducing the number of colors in a paletted image.
@@ -370,31 +402,31 @@ png_set_alpha_mode(png_structp png_ptr, int mode, double output_gamma)
 
 typedef struct png_dsort_struct
 {
-   struct png_dsort_struct FAR * next;
+   struct png_dsort_struct * next;
    png_byte left;
    png_byte right;
 } png_dsort;
-typedef png_dsort FAR *       png_dsortp;
-typedef png_dsort FAR * FAR * png_dsortpp;
+typedef png_dsort *   png_dsortp;
+typedef png_dsort * * png_dsortpp;
 
 void PNGAPI
-png_set_quantize(png_structp png_ptr, png_colorp palette,
+png_set_quantize(png_structrp png_ptr, png_colorp palette,
     int num_palette, int maximum_colors, png_const_uint_16p histogram,
     int full_quantize)
 {
    png_debug(1, "in png_set_quantize");
 
-   if (png_ptr == NULL)
+   if (png_rtran_ok(png_ptr, 0) == 0)
       return;
 
    png_ptr->transformations |= PNG_QUANTIZE;
 
-   if (!full_quantize)
+   if (full_quantize == 0)
    {
       int i;
 
       png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr,
-          (png_uint_32)(num_palette * png_sizeof(png_byte)));
+          (png_uint_32)(num_palette * (sizeof (png_byte))));
       for (i = 0; i < num_palette; i++)
          png_ptr->quantize_index[i] = (png_byte)i;
    }
@@ -411,7 +443,7 @@ png_set_quantize(png_structp png_ptr, png_colorp palette,
 
          /* Initialize an array to sort colors */
          png_ptr->quantize_sort = (png_bytep)png_malloc(png_ptr,
-             (png_uint_32)(num_palette * png_sizeof(png_byte)));
+             (png_uint_32)(num_palette * (sizeof (png_byte))));
 
          /* Initialize the quantize_sort array */
          for (i = 0; i < num_palette; i++)
@@ -444,12 +476,12 @@ png_set_quantize(png_structp png_ptr, png_colorp palette,
                }
             }
 
-            if (done)
+            if (done != 0)
                break;
          }
 
          /* Swap the palette around, and set up a table, if necessary */
-         if (full_quantize)
+         if (full_quantize != 0)
          {
             int j = num_palette;
 
@@ -545,9 +577,9 @@ png_set_quantize(png_structp png_ptr, png_colorp palette,
 
          /* Initialize palette index arrays */
          png_ptr->index_to_palette = (png_bytep)png_malloc(png_ptr,
-             (png_uint_32)(num_palette * png_sizeof(png_byte)));
+             (png_uint_32)(num_palette * (sizeof (png_byte))));
          png_ptr->palette_to_index = (png_bytep)png_malloc(png_ptr,
-             (png_uint_32)(num_palette * png_sizeof(png_byte)));
+             (png_uint_32)(num_palette * (sizeof (png_byte))));
 
          /* Initialize the sort array */
          for (i = 0; i < num_palette; i++)
@@ -557,7 +589,7 @@ png_set_quantize(png_structp png_ptr, png_colorp palette,
          }
 
          hash = (png_dsortpp)png_calloc(png_ptr, (png_uint_32)(769 *
-             png_sizeof(png_dsortp)));
+             (sizeof (png_dsortp))));
 
          num_new_palette = num_palette;
 
@@ -587,7 +619,7 @@ png_set_quantize(png_structp png_ptr, png_colorp palette,
                   {
 
                      t = (png_dsortp)png_malloc_warn(png_ptr,
-                         (png_uint_32)(png_sizeof(png_dsort)));
+                         (png_uint_32)(sizeof (png_dsort)));
 
                      if (t == NULL)
                          break;
@@ -632,7 +664,7 @@ png_set_quantize(png_structp png_ptr, png_colorp palette,
                         num_new_palette--;
                         palette[png_ptr->index_to_palette[j]]
                             = palette[num_new_palette];
-                        if (!full_quantize)
+                        if (full_quantize == 0)
                         {
                            int k;
 
@@ -700,7 +732,7 @@ png_set_quantize(png_structp png_ptr, png_colorp palette,
    }
    png_ptr->num_palette = (png_uint_16)num_palette;
 
-   if (full_quantize)
+   if (full_quantize != 0)
    {
       int i;
       png_bytep distance;
@@ -712,12 +744,12 @@ png_set_quantize(png_structp png_ptr, png_colorp palette,
       png_size_t num_entries = ((png_size_t)1 << total_bits);
 
       png_ptr->palette_lookup = (png_bytep)png_calloc(png_ptr,
-          (png_uint_32)(num_entries * png_sizeof(png_byte)));
+          (png_uint_32)(num_entries * (sizeof (png_byte))));
 
       distance = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_entries *
-          png_sizeof(png_byte)));
+          (sizeof (png_byte))));
 
-      png_memset(distance, 0xff, num_entries * png_sizeof(png_byte));
+      memset(distance, 0xff, num_entries * (sizeof (png_byte)));
 
       for (i = 0; i < num_palette; i++)
       {
@@ -762,23 +794,22 @@ png_set_quantize(png_structp png_ptr, png_colorp palette,
       png_free(png_ptr, distance);
    }
 }
-#endif /* PNG_READ_QUANTIZE_SUPPORTED */
+#endif /* READ_QUANTIZE */
 
 #ifdef PNG_READ_GAMMA_SUPPORTED
 void PNGFAPI
-png_set_gamma_fixed(png_structp png_ptr, png_fixed_point scrn_gamma,
+png_set_gamma_fixed(png_structrp png_ptr, png_fixed_point scrn_gamma,
    png_fixed_point file_gamma)
 {
    png_debug(1, "in png_set_gamma_fixed");
 
-   if (png_ptr == NULL)
+   if (png_rtran_ok(png_ptr, 0) == 0)
       return;
 
    /* New in libpng-1.5.4 - reserve particular negative values as flags. */
    scrn_gamma = translate_gamma_flags(png_ptr, scrn_gamma, 1/*screen*/);
    file_gamma = translate_gamma_flags(png_ptr, file_gamma, 0/*file*/);
 
-#if PNG_LIBPNG_VER >= 10600
    /* Checking the gamma values for being >0 was added in 1.5.4 along with the
     * premultiplied alpha support; this actually hides an undocumented feature
     * of the previous implementation which allowed gamma processing to be
@@ -787,31 +818,32 @@ png_set_gamma_fixed(png_structp png_ptr, png_fixed_point scrn_gamma,
     * accept '0' for the gamma value it takes, because it isn't always used.
     *
     * Since this is an API change (albeit a very minor one that removes an
-    * undocumented API feature) it will not be made until libpng-1.6.0.
+    * undocumented API feature) the following checks were only enabled in
+    * libpng-1.6.0.
     */
    if (file_gamma <= 0)
       png_error(png_ptr, "invalid file gamma in png_set_gamma");
 
    if (scrn_gamma <= 0)
       png_error(png_ptr, "invalid screen gamma in png_set_gamma");
-#endif
 
    /* Set the gamma values unconditionally - this overrides the value in the PNG
     * file if a gAMA chunk was present.  png_set_alpha_mode provides a
     * different, easier, way to default the file gamma.
     */
-   png_ptr->gamma = file_gamma;
+   png_ptr->colorspace.gamma = file_gamma;
+   png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
    png_ptr->screen_gamma = scrn_gamma;
 }
 
 #  ifdef PNG_FLOATING_POINT_SUPPORTED
 void PNGAPI
-png_set_gamma(png_structp png_ptr, double scrn_gamma, double file_gamma)
+png_set_gamma(png_structrp png_ptr, double scrn_gamma, double file_gamma)
 {
    png_set_gamma_fixed(png_ptr, convert_gamma_value(png_ptr, scrn_gamma),
       convert_gamma_value(png_ptr, file_gamma));
 }
-#  endif /* FLOATING_POINT_SUPPORTED */
+#  endif /* FLOATING_POINT */
 #endif /* READ_GAMMA */
 
 #ifdef PNG_READ_EXPAND_SUPPORTED
@@ -820,15 +852,14 @@ png_set_gamma(png_structp png_ptr, double scrn_gamma, double file_gamma)
  * to alpha channels.
  */
 void PNGAPI
-png_set_expand(png_structp png_ptr)
+png_set_expand(png_structrp png_ptr)
 {
    png_debug(1, "in png_set_expand");
 
-   if (png_ptr == NULL)
+   if (png_rtran_ok(png_ptr, 0) == 0)
       return;
 
    png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
-   png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
 }
 
 /* GRR 19990627:  the following three functions currently are identical
@@ -851,90 +882,85 @@ png_set_expand(png_structp png_ptr)
 
 /* Expand paletted images to RGB. */
 void PNGAPI
-png_set_palette_to_rgb(png_structp png_ptr)
+png_set_palette_to_rgb(png_structrp png_ptr)
 {
    png_debug(1, "in png_set_palette_to_rgb");
 
-   if (png_ptr == NULL)
+   if (png_rtran_ok(png_ptr, 0) == 0)
       return;
 
    png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
-   png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
 }
 
 /* Expand grayscale images of less than 8-bit depth to 8 bits. */
 void PNGAPI
-png_set_expand_gray_1_2_4_to_8(png_structp png_ptr)
+png_set_expand_gray_1_2_4_to_8(png_structrp png_ptr)
 {
    png_debug(1, "in png_set_expand_gray_1_2_4_to_8");
 
-   if (png_ptr == NULL)
+   if (png_rtran_ok(png_ptr, 0) == 0)
       return;
 
    png_ptr->transformations |= PNG_EXPAND;
-   png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
 }
 
-
-
 /* Expand tRNS chunks to alpha channels. */
 void PNGAPI
-png_set_tRNS_to_alpha(png_structp png_ptr)
+png_set_tRNS_to_alpha(png_structrp png_ptr)
 {
    png_debug(1, "in png_set_tRNS_to_alpha");
 
+   if (png_rtran_ok(png_ptr, 0) == 0)
+      return;
+
    png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
-   png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
 }
-#endif /* defined(PNG_READ_EXPAND_SUPPORTED) */
+#endif /* READ_EXPAND */
 
 #ifdef PNG_READ_EXPAND_16_SUPPORTED
 /* Expand to 16-bit channels, expand the tRNS chunk too (because otherwise
  * it may not work correctly.)
  */
 void PNGAPI
-png_set_expand_16(png_structp png_ptr)
+png_set_expand_16(png_structrp png_ptr)
 {
    png_debug(1, "in png_set_expand_16");
 
-   if (png_ptr == NULL)
+   if (png_rtran_ok(png_ptr, 0) == 0)
       return;
 
    png_ptr->transformations |= (PNG_EXPAND_16 | PNG_EXPAND | PNG_EXPAND_tRNS);
-   png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
-
-   /* New API, make sure apps call the correct initializers: */
-   png_ptr->flags |= PNG_FLAG_DETECT_UNINITIALIZED;
 }
 #endif
 
 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
 void PNGAPI
-png_set_gray_to_rgb(png_structp png_ptr)
+png_set_gray_to_rgb(png_structrp png_ptr)
 {
    png_debug(1, "in png_set_gray_to_rgb");
 
-   if (png_ptr != NULL)
-   {
-      /* Because rgb must be 8 bits or more: */
-      png_set_expand_gray_1_2_4_to_8(png_ptr);
-      png_ptr->transformations |= PNG_GRAY_TO_RGB;
-      png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
-   }
+   if (png_rtran_ok(png_ptr, 0) == 0)
+      return;
+
+   /* Because rgb must be 8 bits or more: */
+   png_set_expand_gray_1_2_4_to_8(png_ptr);
+   png_ptr->transformations |= PNG_GRAY_TO_RGB;
 }
 #endif
 
 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
 void PNGFAPI
-png_set_rgb_to_gray_fixed(png_structp png_ptr, int error_action,
+png_set_rgb_to_gray_fixed(png_structrp png_ptr, int error_action,
     png_fixed_point red, png_fixed_point green)
 {
    png_debug(1, "in png_set_rgb_to_gray");
 
-   if (png_ptr == NULL)
+   /* Need the IHDR here because of the check on color_type below. */
+   /* TODO: fix this */
+   if (png_rtran_ok(png_ptr, 1) == 0)
       return;
 
-   switch(error_action)
+   switch (error_action)
    {
       case PNG_ERROR_ACTION_NONE:
          png_ptr->transformations |= PNG_RGB_TO_GRAY;
@@ -952,15 +978,19 @@ png_set_rgb_to_gray_fixed(png_structp png_ptr, int error_action,
          png_error(png_ptr, "invalid error action to rgb_to_gray");
          break;
    }
+
    if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
 #ifdef PNG_READ_EXPAND_SUPPORTED
       png_ptr->transformations |= PNG_EXPAND;
 #else
    {
-      png_warning(png_ptr,
+      /* Make this an error in 1.6 because otherwise the application may assume
+       * that it just worked and get a memory overwrite.
+       */
+      png_error(png_ptr,
         "Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED");
 
-      png_ptr->transformations &= ~PNG_RGB_TO_GRAY;
+      /* png_ptr->transformations &= ~PNG_RGB_TO_GRAY; */
    }
 #endif
    {
@@ -969,7 +999,7 @@ png_set_rgb_to_gray_fixed(png_structp png_ptr, int error_action,
          png_uint_16 red_int, green_int;
 
          /* NOTE: this calculation does not round, but this behavior is retained
-          * for consistency, the inaccuracy is very small.  The code here always
+          * for consistency; the inaccuracy is very small.  The code here always
           * overwrites the coefficients, regardless of whether they have been
           * defaulted or set already.
           */
@@ -984,7 +1014,7 @@ png_set_rgb_to_gray_fixed(png_structp png_ptr, int error_action,
       else
       {
          if (red >= 0 && green >= 0)
-            png_warning(png_ptr,
+            png_app_warning(png_ptr,
                "ignoring out of range rgb_to_gray coefficients");
 
          /* Use the defaults, from the cHRM chunk if set, else the historical
@@ -1010,31 +1040,25 @@ png_set_rgb_to_gray_fixed(png_structp png_ptr, int error_action,
  */
 
 void PNGAPI
-png_set_rgb_to_gray(png_structp png_ptr, int error_action, double red,
+png_set_rgb_to_gray(png_structrp png_ptr, int error_action, double red,
    double green)
 {
-   if (png_ptr == NULL)
-      return;
-
    png_set_rgb_to_gray_fixed(png_ptr, error_action,
       png_fixed(png_ptr, red, "rgb to gray red coefficient"),
       png_fixed(png_ptr, green, "rgb to gray green coefficient"));
 }
 #endif /* FLOATING POINT */
 
-#endif
+#endif /* RGB_TO_GRAY */
 
 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
     defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
 void PNGAPI
-png_set_read_user_transform_fn(png_structp png_ptr, png_user_transform_ptr
+png_set_read_user_transform_fn(png_structrp png_ptr, png_user_transform_ptr
     read_user_transform_fn)
 {
    png_debug(1, "in png_set_read_user_transform_fn");
 
-   if (png_ptr == NULL)
-      return;
-
 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
    png_ptr->transformations |= PNG_USER_TRANSFORM;
    png_ptr->read_user_transform_fn = read_user_transform_fn;
@@ -1068,13 +1092,13 @@ png_gamma_threshold(png_fixed_point screen_gamma, png_fixed_point file_gamma)
  * the palette.
  */
 
-/*For the moment 'png_init_palette_transformations' and
+/* For the moment 'png_init_palette_transformations' and
  * 'png_init_rgb_transformations' only do some flag canceling optimizations.
  * The intent is that these two routines should have palette or rgb operations
  * extracted from 'png_init_read_transformations'.
  */
 static void /* PRIVATE */
-png_init_palette_transformations(png_structp png_ptr)
+png_init_palette_transformations(png_structrp png_ptr)
 {
    /* Called to handle the (input) palette case.  In png_do_read_transformations
     * the first step is to expand the palette if requested, so this code must
@@ -1093,25 +1117,31 @@ png_init_palette_transformations(png_structp png_ptr)
 
       /* Ignore if all the entries are opaque (unlikely!) */
       for (i=0; i<png_ptr->num_trans; ++i)
+      {
          if (png_ptr->trans_alpha[i] == 255)
             continue;
          else if (png_ptr->trans_alpha[i] == 0)
             input_has_transparency = 1;
          else
+         {
+            input_has_transparency = 1;
             input_has_alpha = 1;
+            break;
+         }
+      }
    }
 
    /* If no alpha we can optimize. */
-   if (!input_has_alpha)
+   if (input_has_alpha == 0)
    {
       /* Any alpha means background and associative alpha processing is
-       * required, however if the alpha is 0 or 1 throughout OPTIIMIZE_ALPHA
+       * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA
        * and ENCODE_ALPHA are irrelevant.
        */
       png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
       png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
 
-      if (!input_has_transparency)
+      if (input_has_transparency == 0)
          png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
    }
 
@@ -1124,8 +1154,8 @@ png_init_palette_transformations(png_structp png_ptr)
    /* The following code cannot be entered in the alpha pre-multiplication case
     * because PNG_BACKGROUND_EXPAND is cancelled below.
     */
-   if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
-       (png_ptr->transformations & PNG_EXPAND))
+   if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 &&
+       (png_ptr->transformations & PNG_EXPAND) != 0)
    {
       {
          png_ptr->background.red   =
@@ -1136,9 +1166,9 @@ png_init_palette_transformations(png_structp png_ptr)
              png_ptr->palette[png_ptr->background.index].blue;
 
 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
-        if (png_ptr->transformations & PNG_INVERT_ALPHA)
+        if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
         {
-           if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
+           if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0)
            {
               /* Invert the alpha channel (in tRNS) unless the pixels are
                * going to be expanded, in which case leave it for later
@@ -1150,14 +1180,14 @@ png_init_palette_transformations(png_structp png_ptr)
                     png_ptr->trans_alpha[i]);
            }
         }
-#endif /* PNG_READ_INVERT_ALPHA_SUPPORTED */
+#endif /* READ_INVERT_ALPHA */
       }
    } /* background expand and (therefore) no alpha association. */
-#endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */
+#endif /* READ_EXPAND && READ_BACKGROUND */
 }
 
 static void /* PRIVATE */
-png_init_rgb_transformations(png_structp png_ptr)
+png_init_rgb_transformations(png_structrp png_ptr)
 {
    /* Added to libpng-1.5.4: check the color type to determine whether there
     * is any alpha or transparency in the image and simply cancel the
@@ -1167,10 +1197,10 @@ png_init_rgb_transformations(png_structp png_ptr)
    int input_has_transparency = png_ptr->num_trans > 0;
 
    /* If no alpha we can optimize. */
-   if (!input_has_alpha)
+   if (input_has_alpha == 0)
    {
       /* Any alpha means background and associative alpha processing is
-       * required, however if the alpha is 0 or 1 throughout OPTIIMIZE_ALPHA
+       * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA
        * and ENCODE_ALPHA are irrelevant.
        */
 #     ifdef PNG_READ_ALPHA_MODE_SUPPORTED
@@ -1178,7 +1208,7 @@ png_init_rgb_transformations(png_structp png_ptr)
          png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
 #     endif
 
-      if (!input_has_transparency)
+      if (input_has_transparency == 0)
          png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
    }
 
@@ -1191,9 +1221,9 @@ png_init_rgb_transformations(png_structp png_ptr)
    /* The following code cannot be entered in the alpha pre-multiplication case
     * because PNG_BACKGROUND_EXPAND is cancelled below.
     */
-   if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
-       (png_ptr->transformations & PNG_EXPAND) &&
-       !(png_ptr->color_type & PNG_COLOR_MASK_COLOR))
+   if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 &&
+       (png_ptr->transformations & PNG_EXPAND) != 0 &&
+       (png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
        /* i.e., GRAY or GRAY_ALPHA */
    {
       {
@@ -1221,7 +1251,7 @@ png_init_rgb_transformations(png_structp png_ptr)
             default:
 
             case 8:
-               /* Already 8 bits, fall through */
+               /* FALL THROUGH (Already 8 bits) */
 
             case 16:
                /* Already a full 16 bits */
@@ -1231,18 +1261,18 @@ png_init_rgb_transformations(png_structp png_ptr)
          png_ptr->background.red = png_ptr->background.green =
             png_ptr->background.blue = (png_uint_16)gray;
 
-         if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
+         if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0)
          {
             png_ptr->trans_color.red = png_ptr->trans_color.green =
                png_ptr->trans_color.blue = (png_uint_16)trans_gray;
          }
       }
    } /* background expand and (therefore) no alpha association. */
-#endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */
+#endif /* READ_EXPAND && READ_BACKGROUND */
 }
 
 void /* PRIVATE */
-png_init_read_transformations(png_structp png_ptr)
+png_init_read_transformations(png_structrp png_ptr)
 {
    png_debug(1, "in png_init_read_transformations");
 
@@ -1267,17 +1297,17 @@ png_init_read_transformations(png_structp png_ptr)
        */
       int gamma_correction = 0;
 
-      if (png_ptr->gamma != 0) /* has been set */
+      if (png_ptr->colorspace.gamma != 0) /* has been set */
       {
          if (png_ptr->screen_gamma != 0) /* screen set too */
-            gamma_correction = png_gamma_threshold(png_ptr->gamma,
+            gamma_correction = png_gamma_threshold(png_ptr->colorspace.gamma,
                png_ptr->screen_gamma);
 
          else
             /* Assume the output matches the input; a long time default behavior
              * of libpng, although the standard has nothing to say about this.
              */
-            png_ptr->screen_gamma = png_reciprocal(png_ptr->gamma);
+            png_ptr->screen_gamma = png_reciprocal(png_ptr->colorspace.gamma);
       }
 
       else if (png_ptr->screen_gamma != 0)
@@ -1286,7 +1316,7 @@ png_init_read_transformations(png_structp png_ptr)
           * png_set_alpha_mode (even if the alpha handling mode isn't required
           * or isn't changed from the default.)
           */
-         png_ptr->gamma = png_reciprocal(png_ptr->screen_gamma);
+         png_ptr->colorspace.gamma = png_reciprocal(png_ptr->screen_gamma);
 
       else /* neither are set */
          /* Just in case the following prevents any processing - file and screen
@@ -1294,7 +1324,10 @@ png_init_read_transformations(png_structp png_ptr)
           * third gamma value other than png_set_background with 'UNIQUE', and,
           * prior to 1.5.4
           */
-         png_ptr->screen_gamma = png_ptr->gamma = PNG_FP_1;
+         png_ptr->screen_gamma = png_ptr->colorspace.gamma = PNG_FP_1;
+
+      /* We have a gamma value now. */
+      png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
 
       /* Now turn the gamma transformation on or off as appropriate.  Notice
        * that PNG_GAMMA just refers to the file->screen correction.  Alpha
@@ -1304,7 +1337,7 @@ png_init_read_transformations(png_structp png_ptr)
        * the code immediately below if the transform can be handled outside the
        * row loop.
        */
-      if (gamma_correction)
+      if (gamma_correction != 0)
          png_ptr->transformations |= PNG_GAMMA;
 
       else
@@ -1313,7 +1346,7 @@ png_init_read_transformations(png_structp png_ptr)
 #endif
 
    /* Certain transformations have the effect of preventing other
-    * transformations that happen afterward in png_do_read_transformations,
+    * transformations that happen afterward in png_do_read_transformations;
     * resolve the interdependencies here.  From the code of
     * png_do_read_transformations the order is:
     *
@@ -1331,19 +1364,19 @@ png_init_read_transformations(png_structp png_ptr)
     * 12) PNG_EXPAND_16
     * 13) PNG_GRAY_TO_RGB iff PNG_BACKGROUND_IS_GRAY
     * 14) PNG_INVERT_MONO
-    * 15) PNG_SHIFT
-    * 16) PNG_PACK
-    * 17) PNG_BGR
-    * 18) PNG_PACKSWAP
-    * 19) PNG_FILLER (includes PNG_ADD_ALPHA)
-    * 20) PNG_INVERT_ALPHA
+    * 15) PNG_INVERT_ALPHA
+    * 16) PNG_SHIFT
+    * 17) PNG_PACK
+    * 18) PNG_BGR
+    * 19) PNG_PACKSWAP
+    * 20) PNG_FILLER (includes PNG_ADD_ALPHA)
     * 21) PNG_SWAP_ALPHA
     * 22) PNG_SWAP_BYTES
     * 23) PNG_USER_TRANSFORM [must be last]
     */
 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
-   if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
-      !(png_ptr->transformations & PNG_COMPOSE))
+   if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
+       (png_ptr->transformations & PNG_COMPOSE) == 0)
    {
       /* Stripping the alpha channel happens immediately after the 'expand'
        * transformations, before all other transformation, so it cancels out
@@ -1369,16 +1402,23 @@ png_init_read_transformations(png_structp png_ptr)
    /* If the screen gamma is about 1.0 then the OPTIMIZE_ALPHA and ENCODE_ALPHA
     * settings will have no effect.
     */
-   if (!png_gamma_significant(png_ptr->screen_gamma))
+   if (png_gamma_significant(png_ptr->screen_gamma) == 0)
    {
       png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
       png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
    }
 #endif
 
-#if defined(PNG_READ_EXPAND_SUPPORTED) && \
-   defined(PNG_READ_BACKGROUND_SUPPORTED) && \
-   defined(PNG_READ_GRAY_TO_RGB_SUPPORTED)
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+   /* Make sure the coefficients for the rgb to gray conversion are set
+    * appropriately.
+    */
+   if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
+      png_colorspace_set_rgb_coefficients(png_ptr);
+#endif
+
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
+#if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
    /* Detect gray background and attempt to enable optimization for
     * gray --> RGB case.
     *
@@ -1394,23 +1434,23 @@ png_init_read_transformations(png_structp png_ptr)
     * png_set_background, along with the bit depth, then the code has a record
     * of exactly what color space the background is currently in.
     */
-   if (png_ptr->transformations & PNG_BACKGROUND_EXPAND)
+   if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0)
    {
       /* PNG_BACKGROUND_EXPAND: the background is in the file color space, so if
        * the file was grayscale the background value is gray.
        */
-      if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR))
+      if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
          png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
    }
 
-   else if (png_ptr->transformations & PNG_COMPOSE)
+   else if ((png_ptr->transformations & PNG_COMPOSE) != 0)
    {
       /* PNG_COMPOSE: png_set_background was called with need_expand false,
        * so the color is in the color space of the output or png_set_alpha_mode
        * was called and the color is black.  Ignore RGB_TO_GRAY because that
        * happens before GRAY_TO_RGB.
        */
-      if (png_ptr->transformations & PNG_GRAY_TO_RGB)
+      if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
       {
          if (png_ptr->background.red == png_ptr->background.green &&
              png_ptr->background.red == png_ptr->background.blue)
@@ -1420,7 +1460,8 @@ png_init_read_transformations(png_structp png_ptr)
          }
       }
    }
-#endif /* PNG_READ_GRAY_TO_RGB_SUPPORTED (etc) */
+#endif /* READ_EXPAND && READ_BACKGROUND */
+#endif /* READ_GRAY_TO_RGB */
 
    /* For indexed PNG data (PNG_COLOR_TYPE_PALETTE) many of the transformations
     * can be performed directly on the palette, and some (such as rgb to gray)
@@ -1441,10 +1482,10 @@ png_init_read_transformations(png_structp png_ptr)
 
 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
    defined(PNG_READ_EXPAND_16_SUPPORTED)
-   if ((png_ptr->transformations & PNG_EXPAND_16) &&
-      (png_ptr->transformations & PNG_COMPOSE) &&
-      !(png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
-      png_ptr->bit_depth != 16)
+   if ((png_ptr->transformations & PNG_EXPAND_16) != 0 &&
+       (png_ptr->transformations & PNG_COMPOSE) != 0 &&
+       (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 &&
+       png_ptr->bit_depth != 16)
    {
       /* TODO: fix this.  Because the expand_16 operation is after the compose
        * handling the background color must be 8, not 16, bits deep, but the
@@ -1456,22 +1497,22 @@ png_init_read_transformations(png_structp png_ptr)
        * NOTE: this discards the low 16 bits of the user supplied background
        * color, but until expand_16 works properly there is no choice!
        */
-#     define CHOP(x) (x)=((png_uint_16)(((png_uint_32)(x)*255+32895) >> 16))
+#     define CHOP(x) (x)=((png_uint_16)PNG_DIV257(x))
       CHOP(png_ptr->background.red);
       CHOP(png_ptr->background.green);
       CHOP(png_ptr->background.blue);
       CHOP(png_ptr->background.gray);
 #     undef CHOP
    }
-#endif /* PNG_READ_BACKGROUND_SUPPORTED && PNG_READ_EXPAND_16_SUPPORTED */
+#endif /* READ_BACKGROUND && READ_EXPAND_16 */
 
 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
    (defined(PNG_READ_SCALE_16_TO_8_SUPPORTED) || \
    defined(PNG_READ_STRIP_16_TO_8_SUPPORTED))
-   if ((png_ptr->transformations & (PNG_16_TO_8|PNG_SCALE_16_TO_8)) &&
-      (png_ptr->transformations & PNG_COMPOSE) &&
-      !(png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
-      png_ptr->bit_depth == 16)
+   if ((png_ptr->transformations & (PNG_16_TO_8|PNG_SCALE_16_TO_8)) != 0 &&
+       (png_ptr->transformations & PNG_COMPOSE) != 0 &&
+       (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 &&
+       png_ptr->bit_depth == 16)
    {
       /* On the other hand, if a 16-bit file is to be reduced to 8-bits per
        * component this will also happen after PNG_COMPOSE and so the background
@@ -1514,25 +1555,24 @@ png_init_read_transformations(png_structp png_ptr)
     * file gamma - if it is not 1.0 both RGB_TO_GRAY and COMPOSE need the
     * tables.
     */
-   if ((png_ptr->transformations & PNG_GAMMA)
-      || ((png_ptr->transformations & PNG_RGB_TO_GRAY)
-         && (png_gamma_significant(png_ptr->gamma) ||
-            png_gamma_significant(png_ptr->screen_gamma)))
-      || ((png_ptr->transformations & PNG_COMPOSE)
-         && (png_gamma_significant(png_ptr->gamma)
-            || png_gamma_significant(png_ptr->screen_gamma)
+   if ((png_ptr->transformations & PNG_GAMMA) != 0 ||
+       ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0 &&
+        (png_gamma_significant(png_ptr->colorspace.gamma) != 0 ||
+         png_gamma_significant(png_ptr->screen_gamma) != 0)) ||
+        ((png_ptr->transformations & PNG_COMPOSE) != 0 &&
+         (png_gamma_significant(png_ptr->colorspace.gamma) != 0 ||
+          png_gamma_significant(png_ptr->screen_gamma) != 0
 #  ifdef PNG_READ_BACKGROUND_SUPPORTED
-            || (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE
-               && png_gamma_significant(png_ptr->background_gamma))
+         || (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE &&
+           png_gamma_significant(png_ptr->background_gamma) != 0)
 #  endif
-      )) || ((png_ptr->transformations & PNG_ENCODE_ALPHA)
-         && png_gamma_significant(png_ptr->screen_gamma))
-      )
+        )) || ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 &&
+       png_gamma_significant(png_ptr->screen_gamma) != 0))
    {
       png_build_gamma_table(png_ptr, png_ptr->bit_depth);
 
 #ifdef PNG_READ_BACKGROUND_SUPPORTED
-      if (png_ptr->transformations & PNG_COMPOSE)
+      if ((png_ptr->transformations & PNG_COMPOSE) != 0)
       {
          /* Issue a warning about this combination: because RGB_TO_GRAY is
           * optimized to do the gamma transform if present yet do_background has
@@ -1540,11 +1580,11 @@ png_init_read_transformations(png_structp png_ptr)
           * double-gamma-correction happens.  This is true in all versions of
           * libpng to date.
           */
-         if (png_ptr->transformations & PNG_RGB_TO_GRAY)
+         if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
             png_warning(png_ptr,
                "libpng does not support gamma+background+rgb_to_gray");
 
-         if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+         if ((png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) != 0)
          {
             /* We don't get to here unless there is a tRNS chunk with non-opaque
              * entries - see the checking code at the start of this function.
@@ -1576,8 +1616,8 @@ png_init_read_transformations(png_structp png_ptr)
                      break;
 
                   case PNG_BACKGROUND_GAMMA_FILE:
-                     g = png_reciprocal(png_ptr->gamma);
-                     gs = png_reciprocal2(png_ptr->gamma,
+                     g = png_reciprocal(png_ptr->colorspace.gamma);
+                     gs = png_reciprocal2(png_ptr->colorspace.gamma,
                         png_ptr->screen_gamma);
                      break;
 
@@ -1592,7 +1632,7 @@ png_init_read_transformations(png_structp png_ptr)
                      break;
                }
 
-               if (png_gamma_significant(gs))
+               if (png_gamma_significant(gs) != 0)
                {
                   back.red = png_gamma_8bit_correct(png_ptr->background.red,
                       gs);
@@ -1609,7 +1649,7 @@ png_init_read_transformations(png_structp png_ptr)
                   back.blue  = (png_byte)png_ptr->background.blue;
                }
 
-               if (png_gamma_significant(g))
+               if (png_gamma_significant(g) != 0)
                {
                   back_1.red = png_gamma_8bit_correct(png_ptr->background.red,
                      g);
@@ -1685,8 +1725,9 @@ png_init_read_transformations(png_structp png_ptr)
                   break;
 
                case PNG_BACKGROUND_GAMMA_FILE:
-                  g = png_reciprocal(png_ptr->gamma);
-                  gs = png_reciprocal2(png_ptr->gamma, png_ptr->screen_gamma);
+                  g = png_reciprocal(png_ptr->colorspace.gamma);
+                  gs = png_reciprocal2(png_ptr->colorspace.gamma,
+                     png_ptr->screen_gamma);
                   break;
 
                case PNG_BACKGROUND_GAMMA_UNIQUE:
@@ -1702,11 +1743,11 @@ png_init_read_transformations(png_structp png_ptr)
             g_sig = png_gamma_significant(g);
             gs_sig = png_gamma_significant(gs);
 
-            if (g_sig)
+            if (g_sig != 0)
                png_ptr->background_1.gray = png_gamma_correct(png_ptr,
                    png_ptr->background.gray, g);
 
-            if (gs_sig)
+            if (gs_sig != 0)
                png_ptr->background.gray = png_gamma_correct(png_ptr,
                    png_ptr->background.gray, gs);
 
@@ -1715,7 +1756,7 @@ png_init_read_transformations(png_structp png_ptr)
                 (png_ptr->background.red != png_ptr->background.gray))
             {
                /* RGB or RGBA with color background */
-               if (g_sig)
+               if (g_sig != 0)
                {
                   png_ptr->background_1.red = png_gamma_correct(png_ptr,
                       png_ptr->background.red, g);
@@ -1727,7 +1768,7 @@ png_init_read_transformations(png_structp png_ptr)
                       png_ptr->background.blue, g);
                }
 
-               if (gs_sig)
+               if (gs_sig != 0)
                {
                   png_ptr->background.red = png_gamma_correct(png_ptr,
                       png_ptr->background.red, gs);
@@ -1757,7 +1798,7 @@ png_init_read_transformations(png_structp png_ptr)
 
       else
       /* Transformation does not include PNG_BACKGROUND */
-#endif /* PNG_READ_BACKGROUND_SUPPORTED */
+#endif /* READ_BACKGROUND */
       if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE
 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
          /* RGB_TO_GRAY needs to have non-gamma-corrected values! */
@@ -1770,8 +1811,8 @@ png_init_read_transformations(png_structp png_ptr)
          int num_palette = png_ptr->num_palette;
          int i;
 
-         /*NOTE: there are other transformations that should probably be in here
-          * too.
+         /* NOTE: there are other transformations that should probably be in
+          * here too.
           */
          for (i = 0; i < num_palette; i++)
          {
@@ -1787,11 +1828,11 @@ png_init_read_transformations(png_structp png_ptr)
 #ifdef PNG_READ_BACKGROUND_SUPPORTED
    else
 #endif
-#endif /* PNG_READ_GAMMA_SUPPORTED */
+#endif /* READ_GAMMA */
 
 #ifdef PNG_READ_BACKGROUND_SUPPORTED
    /* No GAMMA transformation (see the hanging else 4 lines above) */
-   if ((png_ptr->transformations & PNG_COMPOSE) &&
+   if ((png_ptr->transformations & PNG_COMPOSE) != 0 &&
        (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
    {
       int i;
@@ -1826,11 +1867,11 @@ png_init_read_transformations(png_structp png_ptr)
 
       png_ptr->transformations &= ~PNG_COMPOSE;
    }
-#endif /* PNG_READ_BACKGROUND_SUPPORTED */
+#endif /* READ_BACKGROUND */
 
 #ifdef PNG_READ_SHIFT_SUPPORTED
-   if ((png_ptr->transformations & PNG_SHIFT) &&
-      !(png_ptr->transformations & PNG_EXPAND) &&
+   if ((png_ptr->transformations & PNG_SHIFT) != 0 &&
+       (png_ptr->transformations & PNG_EXPAND) == 0 &&
        (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
    {
       int i;
@@ -1843,33 +1884,36 @@ png_init_read_transformations(png_structp png_ptr)
        * the number of significant bits is 0 then no shift is done (this is an
        * error condition which is silently ignored.)
        */
-      if (shift > 0 && shift < 8) for (i=0; i<istop; ++i)
-      {
-         int component = png_ptr->palette[i].red;
+      if (shift > 0 && shift < 8)
+         for (i=0; i<istop; ++i)
+         {
+            int component = png_ptr->palette[i].red;
 
-         component >>= shift;
-         png_ptr->palette[i].red = (png_byte)component;
-      }
+            component >>= shift;
+            png_ptr->palette[i].red = (png_byte)component;
+         }
 
       shift = 8 - png_ptr->sig_bit.green;
-      if (shift > 0 && shift < 8) for (i=0; i<istop; ++i)
-      {
-         int component = png_ptr->palette[i].green;
+      if (shift > 0 && shift < 8)
+         for (i=0; i<istop; ++i)
+         {
+            int component = png_ptr->palette[i].green;
 
-         component >>= shift;
-         png_ptr->palette[i].green = (png_byte)component;
-      }
+            component >>= shift;
+            png_ptr->palette[i].green = (png_byte)component;
+         }
 
       shift = 8 - png_ptr->sig_bit.blue;
-      if (shift > 0 && shift < 8) for (i=0; i<istop; ++i)
-      {
-         int component = png_ptr->palette[i].blue;
+      if (shift > 0 && shift < 8)
+         for (i=0; i<istop; ++i)
+         {
+            int component = png_ptr->palette[i].blue;
 
-         component >>= shift;
-         png_ptr->palette[i].blue = (png_byte)component;
-      }
+            component >>= shift;
+            png_ptr->palette[i].blue = (png_byte)component;
+         }
    }
-#endif  /* PNG_READ_SHIFT_SUPPORTED */
+#endif  /* READ_SHIFT */
 }
 
 /* Modify the info structure to reflect the transformations.  The
@@ -1877,12 +1921,12 @@ png_init_read_transformations(png_structp png_ptr)
  * assuming the transformations result in valid PNG data.
  */
 void /* PRIVATE */
-png_read_transform_info(png_structp png_ptr, png_infop info_ptr)
+png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
 {
    png_debug(1, "in png_read_transform_info");
 
 #ifdef PNG_READ_EXPAND_SUPPORTED
-   if (png_ptr->transformations & PNG_EXPAND)
+   if ((png_ptr->transformations & PNG_EXPAND) != 0)
    {
       if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
       {
@@ -1898,12 +1942,15 @@ png_read_transform_info(png_structp png_ptr, png_infop info_ptr)
 
          info_ptr->bit_depth = 8;
          info_ptr->num_trans = 0;
+
+         if (png_ptr->palette == NULL)
+            png_error (png_ptr, "Palette is NULL in indexed image");
       }
       else
       {
-         if (png_ptr->num_trans)
+         if (png_ptr->num_trans != 0)
          {
-            if (png_ptr->transformations & PNG_EXPAND_tRNS)
+            if ((png_ptr->transformations & PNG_EXPAND_tRNS) != 0)
                info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
          }
          if (info_ptr->bit_depth < 8)
@@ -1919,7 +1966,7 @@ png_read_transform_info(png_structp png_ptr, png_infop info_ptr)
    /* The following is almost certainly wrong unless the background value is in
     * the screen space!
     */
-   if (png_ptr->transformations & PNG_COMPOSE)
+   if ((png_ptr->transformations & PNG_COMPOSE) != 0)
       info_ptr->background = png_ptr->background;
 #endif
 
@@ -1928,20 +1975,24 @@ png_read_transform_info(png_structp png_ptr, png_infop info_ptr)
     * however it seems that the code in png_init_read_transformations, which has
     * been called before this from png_read_update_info->png_read_start_row
     * sometimes does the gamma transform and cancels the flag.
+    *
+    * TODO: this looks wrong; the info_ptr should end up with a gamma equal to
+    * the screen_gamma value.  The following probably results in weirdness if
+    * the info_ptr is used by the app after the rows have been read.
     */
-   info_ptr->gamma = png_ptr->gamma;
+   info_ptr->colorspace.gamma = png_ptr->colorspace.gamma;
 #endif
 
    if (info_ptr->bit_depth == 16)
    {
 #  ifdef PNG_READ_16BIT_SUPPORTED
 #     ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
-         if (png_ptr->transformations & PNG_SCALE_16_TO_8)
+         if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0)
             info_ptr->bit_depth = 8;
 #     endif
 
 #     ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
-         if (png_ptr->transformations & PNG_16_TO_8)
+         if ((png_ptr->transformations & PNG_16_TO_8) != 0)
             info_ptr->bit_depth = 8;
 #     endif
 
@@ -1967,27 +2018,27 @@ png_read_transform_info(png_structp png_ptr, png_infop info_ptr)
             CONFIGURATION ERROR: you must enable at least one 16 to 8 method
 #        endif
 #    endif
-#endif /* !READ_16BIT_SUPPORTED */
+#endif /* !READ_16BIT */
    }
 
 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
-   if (png_ptr->transformations & PNG_GRAY_TO_RGB)
+   if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
       info_ptr->color_type = (png_byte)(info_ptr->color_type |
          PNG_COLOR_MASK_COLOR);
 #endif
 
 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
-   if (png_ptr->transformations & PNG_RGB_TO_GRAY)
+   if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
       info_ptr->color_type = (png_byte)(info_ptr->color_type &
          ~PNG_COLOR_MASK_COLOR);
 #endif
 
 #ifdef PNG_READ_QUANTIZE_SUPPORTED
-   if (png_ptr->transformations & PNG_QUANTIZE)
+   if ((png_ptr->transformations & PNG_QUANTIZE) != 0)
    {
       if (((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
           (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)) &&
-          png_ptr->palette_lookup && info_ptr->bit_depth == 8)
+          png_ptr->palette_lookup != 0 && info_ptr->bit_depth == 8)
       {
          info_ptr->color_type = PNG_COLOR_TYPE_PALETTE;
       }
@@ -1995,29 +2046,31 @@ png_read_transform_info(png_structp png_ptr, png_infop info_ptr)
 #endif
 
 #ifdef PNG_READ_EXPAND_16_SUPPORTED
-   if (png_ptr->transformations & PNG_EXPAND_16 && info_ptr->bit_depth == 8 &&
-      info_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
+   if ((png_ptr->transformations & PNG_EXPAND_16) != 0 &&
+       info_ptr->bit_depth == 8 &&
+       info_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
    {
       info_ptr->bit_depth = 16;
    }
 #endif
 
 #ifdef PNG_READ_PACK_SUPPORTED
-   if ((png_ptr->transformations & PNG_PACK) && (info_ptr->bit_depth < 8))
+   if ((png_ptr->transformations & PNG_PACK) != 0 &&
+       (info_ptr->bit_depth < 8))
       info_ptr->bit_depth = 8;
 #endif
 
    if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
       info_ptr->channels = 1;
 
-   else if (info_ptr->color_type & PNG_COLOR_MASK_COLOR)
+   else if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
       info_ptr->channels = 3;
 
    else
       info_ptr->channels = 1;
 
 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
-   if (png_ptr->transformations & PNG_STRIP_ALPHA)
+   if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0)
    {
       info_ptr->color_type = (png_byte)(info_ptr->color_type &
          ~PNG_COLOR_MASK_ALPHA);
@@ -2025,25 +2078,25 @@ png_read_transform_info(png_structp png_ptr, png_infop info_ptr)
    }
 #endif
 
-   if (info_ptr->color_type & PNG_COLOR_MASK_ALPHA)
+   if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
       info_ptr->channels++;
 
 #ifdef PNG_READ_FILLER_SUPPORTED
    /* STRIP_ALPHA and FILLER allowed:  MASK_ALPHA bit stripped above */
-   if ((png_ptr->transformations & PNG_FILLER) &&
-       ((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
-       (info_ptr->color_type == PNG_COLOR_TYPE_GRAY)))
+   if ((png_ptr->transformations & PNG_FILLER) != 0 &&
+       (info_ptr->color_type == PNG_COLOR_TYPE_RGB ||
+       info_ptr->color_type == PNG_COLOR_TYPE_GRAY))
    {
       info_ptr->channels++;
       /* If adding a true alpha channel not just filler */
-      if (png_ptr->transformations & PNG_ADD_ALPHA)
+      if ((png_ptr->transformations & PNG_ADD_ALPHA) != 0)
          info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
    }
 #endif
 
 #if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \
 defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
-   if (png_ptr->transformations & PNG_USER_TRANSFORM)
+   if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
    {
       if (info_ptr->bit_depth < png_ptr->user_transform_depth)
          info_ptr->bit_depth = png_ptr->user_transform_depth;
@@ -2067,306 +2120,11 @@ defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
    png_ptr->info_rowbytes = info_ptr->rowbytes;
 
 #ifndef PNG_READ_EXPAND_SUPPORTED
-   if (png_ptr)
+   if (png_ptr != NULL)
       return;
 #endif
 }
 
-/* Transform the row.  The order of transformations is significant,
- * and is very touchy.  If you add a transformation, take care to
- * decide how it fits in with the other transformations here.
- */
-void /* PRIVATE */
-png_do_read_transformations(png_structp png_ptr, png_row_infop row_info)
-{
-   png_debug(1, "in png_do_read_transformations");
-
-   if (png_ptr->row_buf == NULL)
-   {
-      /* Prior to 1.5.4 this output row/pass where the NULL pointer is, but this
-       * error is incredibly rare and incredibly easy to debug without this
-       * information.
-       */
-      png_error(png_ptr, "NULL row buffer");
-   }
-
-   /* The following is debugging; prior to 1.5.4 the code was never compiled in;
-    * in 1.5.4 PNG_FLAG_DETECT_UNINITIALIZED was added and the macro
-    * PNG_WARN_UNINITIALIZED_ROW removed.  In 1.5 the new flag is set only for
-    * selected new APIs to ensure that there is no API change.
-    */
-   if ((png_ptr->flags & PNG_FLAG_DETECT_UNINITIALIZED) != 0 &&
-      !(png_ptr->flags & PNG_FLAG_ROW_INIT))
-   {
-      /* Application has failed to call either png_read_start_image() or
-       * png_read_update_info() after setting transforms that expand pixels.
-       * This check added to libpng-1.2.19 (but not enabled until 1.5.4).
-       */
-      png_error(png_ptr, "Uninitialized row");
-   }
-
-#ifdef PNG_READ_EXPAND_SUPPORTED
-   if (png_ptr->transformations & PNG_EXPAND)
-   {
-      if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
-      {
-         png_do_expand_palette(row_info, png_ptr->row_buf + 1,
-             png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans);
-      }
-
-      else
-      {
-         if (png_ptr->num_trans &&
-             (png_ptr->transformations & PNG_EXPAND_tRNS))
-            png_do_expand(row_info, png_ptr->row_buf + 1,
-                &(png_ptr->trans_color));
-
-         else
-            png_do_expand(row_info, png_ptr->row_buf + 1,
-                NULL);
-      }
-   }
-#endif
-
-#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
-   if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
-      !(png_ptr->transformations & PNG_COMPOSE) &&
-      (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
-      row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
-      png_do_strip_channel(row_info, png_ptr->row_buf + 1,
-         0 /* at_start == false, because SWAP_ALPHA happens later */);
-#endif
-
-#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
-   if (png_ptr->transformations & PNG_RGB_TO_GRAY)
-   {
-      int rgb_error =
-          png_do_rgb_to_gray(png_ptr, row_info,
-              png_ptr->row_buf + 1);
-
-      if (rgb_error)
-      {
-         png_ptr->rgb_to_gray_status=1;
-         if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
-             PNG_RGB_TO_GRAY_WARN)
-            png_warning(png_ptr, "png_do_rgb_to_gray found nongray pixel");
-
-         if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
-             PNG_RGB_TO_GRAY_ERR)
-            png_error(png_ptr, "png_do_rgb_to_gray found nongray pixel");
-      }
-   }
-#endif
-
-/* From Andreas Dilger e-mail to png-implement, 26 March 1998:
- *
- *   In most cases, the "simple transparency" should be done prior to doing
- *   gray-to-RGB, or you will have to test 3x as many bytes to check if a
- *   pixel is transparent.  You would also need to make sure that the
- *   transparency information is upgraded to RGB.
- *
- *   To summarize, the current flow is:
- *   - Gray + simple transparency -> compare 1 or 2 gray bytes and composite
- *                                   with background "in place" if transparent,
- *                                   convert to RGB if necessary
- *   - Gray + alpha -> composite with gray background and remove alpha bytes,
- *                                   convert to RGB if necessary
- *
- *   To support RGB backgrounds for gray images we need:
- *   - Gray + simple transparency -> convert to RGB + simple transparency,
- *                                   compare 3 or 6 bytes and composite with
- *                                   background "in place" if transparent
- *                                   (3x compare/pixel compared to doing
- *                                   composite with gray bkgrnd)
- *   - Gray + alpha -> convert to RGB + alpha, composite with background and
- *                                   remove alpha bytes (3x float
- *                                   operations/pixel compared with composite
- *                                   on gray background)
- *
- *  Greg's change will do this.  The reason it wasn't done before is for
- *  performance, as this increases the per-pixel operations.  If we would check
- *  in advance if the background was gray or RGB, and position the gray-to-RGB
- *  transform appropriately, then it would save a lot of work/time.
- */
-
-#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
-   /* If gray -> RGB, do so now only if background is non-gray; else do later
-    * for performance reasons
-    */
-   if ((png_ptr->transformations & PNG_GRAY_TO_RGB) &&
-       !(png_ptr->mode & PNG_BACKGROUND_IS_GRAY))
-      png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
-#endif
-
-#if (defined PNG_READ_BACKGROUND_SUPPORTED) ||\
-   (defined PNG_READ_ALPHA_MODE_SUPPORTED)
-   if (png_ptr->transformations & PNG_COMPOSE)
-      png_do_compose(row_info, png_ptr->row_buf + 1, png_ptr);
-#endif
-
-#ifdef PNG_READ_GAMMA_SUPPORTED
-   if ((png_ptr->transformations & PNG_GAMMA) &&
-#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
-      /* Because RGB_TO_GRAY does the gamma transform. */
-      !(png_ptr->transformations & PNG_RGB_TO_GRAY) &&
-#endif
-#if (defined PNG_READ_BACKGROUND_SUPPORTED) ||\
-   (defined PNG_READ_ALPHA_MODE_SUPPORTED)
-      /* Because PNG_COMPOSE does the gamma transform if there is something to
-       * do (if there is an alpha channel or transparency.)
-       */
-       !((png_ptr->transformations & PNG_COMPOSE) &&
-       ((png_ptr->num_trans != 0) ||
-       (png_ptr->color_type & PNG_COLOR_MASK_ALPHA))) &&
-#endif
-      /* Because png_init_read_transformations transforms the palette, unless
-       * RGB_TO_GRAY will do the transform.
-       */
-       (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE))
-      png_do_gamma(row_info, png_ptr->row_buf + 1, png_ptr);
-#endif
-
-#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
-   if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
-      (png_ptr->transformations & PNG_COMPOSE) &&
-      (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
-      row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
-      png_do_strip_channel(row_info, png_ptr->row_buf + 1,
-         0 /* at_start == false, because SWAP_ALPHA happens later */);
-#endif
-
-#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
-   if ((png_ptr->transformations & PNG_ENCODE_ALPHA) &&
-      (row_info->color_type & PNG_COLOR_MASK_ALPHA))
-      png_do_encode_alpha(row_info, png_ptr->row_buf + 1, png_ptr);
-#endif
-
-#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
-   if (png_ptr->transformations & PNG_SCALE_16_TO_8)
-      png_do_scale_16_to_8(row_info, png_ptr->row_buf + 1);
-#endif
-
-#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
-   /* There is no harm in doing both of these because only one has any effect,
-    * by putting the 'scale' option first if the app asks for scale (either by
-    * calling the API or in a TRANSFORM flag) this is what happens.
-    */
-   if (png_ptr->transformations & PNG_16_TO_8)
-      png_do_chop(row_info, png_ptr->row_buf + 1);
-#endif
-
-#ifdef PNG_READ_QUANTIZE_SUPPORTED
-   if (png_ptr->transformations & PNG_QUANTIZE)
-   {
-      png_do_quantize(row_info, png_ptr->row_buf + 1,
-          png_ptr->palette_lookup, png_ptr->quantize_index);
-
-      if (row_info->rowbytes == 0)
-         png_error(png_ptr, "png_do_quantize returned rowbytes=0");
-   }
-#endif /* PNG_READ_QUANTIZE_SUPPORTED */
-
-#ifdef PNG_READ_EXPAND_16_SUPPORTED
-   /* Do the expansion now, after all the arithmetic has been done.  Notice
-    * that previous transformations can handle the PNG_EXPAND_16 flag if this
-    * is efficient (particularly true in the case of gamma correction, where
-    * better accuracy results faster!)
-    */
-   if (png_ptr->transformations & PNG_EXPAND_16)
-      png_do_expand_16(row_info, png_ptr->row_buf + 1);
-#endif
-
-#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
-   /*NOTE: moved here in 1.5.4 (from much later in this list.) */
-   if ((png_ptr->transformations & PNG_GRAY_TO_RGB) &&
-       (png_ptr->mode & PNG_BACKGROUND_IS_GRAY))
-      png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
-#endif
-
-#ifdef PNG_READ_INVERT_SUPPORTED
-   if (png_ptr->transformations & PNG_INVERT_MONO)
-      png_do_invert(row_info, png_ptr->row_buf + 1);
-#endif
-
-#ifdef PNG_READ_SHIFT_SUPPORTED
-   if (png_ptr->transformations & PNG_SHIFT)
-      png_do_unshift(row_info, png_ptr->row_buf + 1,
-          &(png_ptr->shift));
-#endif
-
-#ifdef PNG_READ_PACK_SUPPORTED
-   if (png_ptr->transformations & PNG_PACK)
-      png_do_unpack(row_info, png_ptr->row_buf + 1);
-#endif
-
-#ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
-   /* Added at libpng-1.5.10 */
-   if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
-      png_do_check_palette_indexes(png_ptr, row_info);
-#endif
-
-#ifdef PNG_READ_BGR_SUPPORTED
-   if (png_ptr->transformations & PNG_BGR)
-      png_do_bgr(row_info, png_ptr->row_buf + 1);
-#endif
-
-#ifdef PNG_READ_PACKSWAP_SUPPORTED
-   if (png_ptr->transformations & PNG_PACKSWAP)
-      png_do_packswap(row_info, png_ptr->row_buf + 1);
-#endif
-
-#ifdef PNG_READ_FILLER_SUPPORTED
-   if (png_ptr->transformations & PNG_FILLER)
-      png_do_read_filler(row_info, png_ptr->row_buf + 1,
-          (png_uint_32)png_ptr->filler, png_ptr->flags);
-#endif
-
-#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
-   if (png_ptr->transformations & PNG_INVERT_ALPHA)
-      png_do_read_invert_alpha(row_info, png_ptr->row_buf + 1);
-#endif
-
-#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
-   if (png_ptr->transformations & PNG_SWAP_ALPHA)
-      png_do_read_swap_alpha(row_info, png_ptr->row_buf + 1);
-#endif
-
-#ifdef PNG_READ_16BIT_SUPPORTED
-#ifdef PNG_READ_SWAP_SUPPORTED
-   if (png_ptr->transformations & PNG_SWAP_BYTES)
-      png_do_swap(row_info, png_ptr->row_buf + 1);
-#endif
-#endif
-
-#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
-   if (png_ptr->transformations & PNG_USER_TRANSFORM)
-    {
-      if (png_ptr->read_user_transform_fn != NULL)
-         (*(png_ptr->read_user_transform_fn)) /* User read transform function */
-             (png_ptr,     /* png_ptr */
-             row_info,     /* row_info: */
-                /*  png_uint_32 width;       width of row */
-                /*  png_size_t rowbytes;     number of bytes in row */
-                /*  png_byte color_type;     color type of pixels */
-                /*  png_byte bit_depth;      bit depth of samples */
-                /*  png_byte channels;       number of channels (1-4) */
-                /*  png_byte pixel_depth;    bits per pixel (depth*channels) */
-             png_ptr->row_buf + 1);    /* start of pixel data for row */
-#ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
-      if (png_ptr->user_transform_depth)
-         row_info->bit_depth = png_ptr->user_transform_depth;
-
-      if (png_ptr->user_transform_channels)
-         row_info->channels = png_ptr->user_transform_channels;
-#endif
-      row_info->pixel_depth = (png_byte)(row_info->bit_depth *
-          row_info->channels);
-
-      row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_info->width);
-   }
-#endif
-}
-
 #ifdef PNG_READ_PACK_SUPPORTED
 /* Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel,
  * without changing the actual values.  Thus, if you had a row with
@@ -2374,7 +2132,7 @@ png_do_read_transformations(png_structp png_ptr, png_row_infop row_info)
  * the numbers 0 or 1.  If you would rather they contain 0 and 255, use
  * png_do_shift() after this.
  */
-void /* PRIVATE */
+static void
 png_do_unpack(png_row_infop row_info, png_bytep row)
 {
    png_debug(1, "in png_do_unpack");
@@ -2472,7 +2230,7 @@ png_do_unpack(png_row_infop row_info, png_bytep row)
  * a row of bit depth 8, but only 5 are significant, this will shift
  * the values back to 0 through 31.
  */
-void /* PRIVATE */
+static void
 png_do_unshift(png_row_infop row_info, png_bytep row,
     png_const_color_8p sig_bits)
 {
@@ -2489,7 +2247,7 @@ png_do_unshift(png_row_infop row_info, png_bytep row,
       int channels = 0;
       int bit_depth = row_info->bit_depth;
 
-      if (color_type & PNG_COLOR_MASK_COLOR)
+      if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
       {
          shift[channels++] = bit_depth - sig_bits->red;
          shift[channels++] = bit_depth - sig_bits->green;
@@ -2501,7 +2259,7 @@ png_do_unshift(png_row_infop row_info, png_bytep row,
          shift[channels++] = bit_depth - sig_bits->gray;
       }
 
-      if (color_type & PNG_COLOR_MASK_ALPHA)
+      if ((color_type & PNG_COLOR_MASK_ALPHA) != 0)
       {
          shift[channels++] = bit_depth - sig_bits->alpha;
       }
@@ -2521,7 +2279,7 @@ png_do_unshift(png_row_infop row_info, png_bytep row,
                have_shift = 1;
          }
 
-         if (!have_shift)
+         if (have_shift == 0)
             return;
       }
 
@@ -2599,7 +2357,7 @@ png_do_unshift(png_row_infop row_info, png_bytep row,
                if (++channel >= channels)
                   channel = 0;
                *bp++ = (png_byte)(value >> 8);
-               *bp++ = (png_byte)(value & 0xff);
+               *bp++ = (png_byte)value;
             }
             break;
          }
@@ -2611,7 +2369,7 @@ png_do_unshift(png_row_infop row_info, png_bytep row,
 
 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
 /* Scale rows of bit depth 16 down to 8 accurately */
-void /* PRIVATE */
+static void
 png_do_scale_16_to_8(png_row_infop row_info, png_bytep row)
 {
    png_debug(1, "in png_do_scale_16_to_8");
@@ -2669,7 +2427,7 @@ png_do_scale_16_to_8(png_row_infop row_info, png_bytep row)
 #endif
 
 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
-void /* PRIVATE */
+static void
 /* Simply discard the low byte.  This was the default behavior prior
  * to libpng-1.5.4.
  */
@@ -2697,7 +2455,7 @@ png_do_chop(png_row_infop row_info, png_bytep row)
 #endif
 
 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
-void /* PRIVATE */
+static void
 png_do_read_swap_alpha(png_row_infop row_info, png_bytep row)
 {
    png_debug(1, "in png_do_read_swap_alpha");
@@ -2794,7 +2552,7 @@ png_do_read_swap_alpha(png_row_infop row_info, png_bytep row)
 #endif
 
 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
-void /* PRIVATE */
+static void
 png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
 {
    png_uint_32 row_width;
@@ -2896,7 +2654,7 @@ png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
 
 #ifdef PNG_READ_FILLER_SUPPORTED
 /* Add filler channel if we have RGB color */
-void /* PRIVATE */
+static void
 png_do_read_filler(png_row_infop row_info, png_bytep row,
     png_uint_32 filler, png_uint_32 flags)
 {
@@ -2904,9 +2662,9 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
    png_uint_32 row_width = row_info->width;
 
 #ifdef PNG_READ_16BIT_SUPPORTED
-   png_byte hi_filler = (png_byte)((filler>>8) & 0xff);
+   png_byte hi_filler = (png_byte)(filler>>8);
 #endif
-   png_byte lo_filler = (png_byte)(filler & 0xff);
+   png_byte lo_filler = (png_byte)filler;
 
    png_debug(1, "in png_do_read_filler");
 
@@ -2915,7 +2673,7 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
    {
       if (row_info->bit_depth == 8)
       {
-         if (flags & PNG_FLAG_FILLER_AFTER)
+         if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
          {
             /* This changes the data from G to GX */
             png_bytep sp = row + (png_size_t)row_width;
@@ -2950,20 +2708,20 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
 #ifdef PNG_READ_16BIT_SUPPORTED
       else if (row_info->bit_depth == 16)
       {
-         if (flags & PNG_FLAG_FILLER_AFTER)
+         if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
          {
             /* This changes the data from GG to GGXX */
             png_bytep sp = row + (png_size_t)row_width * 2;
             png_bytep dp = sp  + (png_size_t)row_width * 2;
             for (i = 1; i < row_width; i++)
             {
-               *(--dp) = hi_filler;
                *(--dp) = lo_filler;
+               *(--dp) = hi_filler;
                *(--dp) = *(--sp);
                *(--dp) = *(--sp);
             }
-            *(--dp) = hi_filler;
             *(--dp) = lo_filler;
+            *(--dp) = hi_filler;
             row_info->channels = 2;
             row_info->pixel_depth = 32;
             row_info->rowbytes = row_width * 4;
@@ -2978,8 +2736,8 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
             {
                *(--dp) = *(--sp);
                *(--dp) = *(--sp);
-               *(--dp) = hi_filler;
                *(--dp) = lo_filler;
+               *(--dp) = hi_filler;
             }
             row_info->channels = 2;
             row_info->pixel_depth = 32;
@@ -2992,7 +2750,7 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
    {
       if (row_info->bit_depth == 8)
       {
-         if (flags & PNG_FLAG_FILLER_AFTER)
+         if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
          {
             /* This changes the data from RGB to RGBX */
             png_bytep sp = row + (png_size_t)row_width * 3;
@@ -3031,15 +2789,15 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
 #ifdef PNG_READ_16BIT_SUPPORTED
       else if (row_info->bit_depth == 16)
       {
-         if (flags & PNG_FLAG_FILLER_AFTER)
+         if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
          {
             /* This changes the data from RRGGBB to RRGGBBXX */
             png_bytep sp = row + (png_size_t)row_width * 6;
             png_bytep dp = sp  + (png_size_t)row_width * 2;
             for (i = 1; i < row_width; i++)
             {
-               *(--dp) = hi_filler;
                *(--dp) = lo_filler;
+               *(--dp) = hi_filler;
                *(--dp) = *(--sp);
                *(--dp) = *(--sp);
                *(--dp) = *(--sp);
@@ -3047,8 +2805,8 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
                *(--dp) = *(--sp);
                *(--dp) = *(--sp);
             }
-            *(--dp) = hi_filler;
             *(--dp) = lo_filler;
+            *(--dp) = hi_filler;
             row_info->channels = 4;
             row_info->pixel_depth = 64;
             row_info->rowbytes = row_width * 8;
@@ -3067,8 +2825,8 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
                *(--dp) = *(--sp);
                *(--dp) = *(--sp);
                *(--dp) = *(--sp);
-               *(--dp) = hi_filler;
                *(--dp) = lo_filler;
+               *(--dp) = hi_filler;
             }
 
             row_info->channels = 4;
@@ -3083,7 +2841,7 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
 
 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
 /* Expand grayscale files to RGB, with or without alpha */
-void /* PRIVATE */
+static void
 png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
 {
    png_uint_32 i;
@@ -3092,7 +2850,7 @@ png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
    png_debug(1, "in png_do_gray_to_rgb");
 
    if (row_info->bit_depth >= 8 &&
-       !(row_info->color_type & PNG_COLOR_MASK_COLOR))
+       (row_info->color_type & PNG_COLOR_MASK_COLOR) == 0)
    {
       if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
       {
@@ -3222,16 +2980,16 @@ png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
  *  calculated to make the sum 32768.  This will result in different rounding
  *  to that used above.
  */
-int /* PRIVATE */
-png_do_rgb_to_gray(png_structp png_ptr, png_row_infop row_info, png_bytep row)
+static int
+png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
 
 {
    int rgb_error = 0;
 
    png_debug(1, "in png_do_rgb_to_gray");
 
-   if (!(row_info->color_type & PNG_COLOR_MASK_PALETTE) &&
-       (row_info->color_type & PNG_COLOR_MASK_COLOR))
+   if ((row_info->color_type & PNG_COLOR_MASK_PALETTE) == 0 &&
+       (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
    {
       PNG_CONST png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff;
       PNG_CONST png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff;
@@ -3242,7 +3000,7 @@ png_do_rgb_to_gray(png_structp png_ptr, png_row_infop row_info, png_bytep row)
 
       if (row_info->bit_depth == 8)
       {
-#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
          /* Notice that gamma to/from 1 are not necessarily inverses (if
           * there is an overall gamma correction).  Prior to 1.5.5 this code
           * checked the linearized values for equality; this doesn't match
@@ -3282,7 +3040,7 @@ png_do_rgb_to_gray(png_structp png_ptr, png_row_infop row_info, png_bytep row)
                   *(dp++) = red;
                }
 
-               if (have_alpha)
+               if (have_alpha != 0)
                   *(dp++) = *(sp++);
             }
          }
@@ -3302,7 +3060,7 @@ png_do_rgb_to_gray(png_structp png_ptr, png_row_infop row_info, png_bytep row)
                if (red != green || red != blue)
                {
                   rgb_error |= 1;
-                  /*NOTE: this is the historical approach which simply
+                  /* NOTE: this is the historical approach which simply
                    * truncates the results.
                    */
                   *(dp++) = (png_byte)((rc*red + gc*green + bc*blue)>>15);
@@ -3311,7 +3069,7 @@ png_do_rgb_to_gray(png_structp png_ptr, png_row_infop row_info, png_bytep row)
                else
                   *(dp++) = red;
 
-               if (have_alpha)
+               if (have_alpha != 0)
                   *(dp++) = *(sp++);
             }
          }
@@ -3319,7 +3077,7 @@ png_do_rgb_to_gray(png_structp png_ptr, png_row_infop row_info, png_bytep row)
 
       else /* RGB bit_depth == 16 */
       {
-#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
          if (png_ptr->gamma_16_to_1 != NULL && png_ptr->gamma_16_from_1 != NULL)
          {
             png_bytep sp = row;
@@ -3329,16 +3087,17 @@ png_do_rgb_to_gray(png_structp png_ptr, png_row_infop row_info, png_bytep row)
             for (i = 0; i < row_width; i++)
             {
                png_uint_16 red, green, blue, w;
+               png_byte hi,lo;
 
-               red   = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
-               green = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
-               blue  = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
+               hi=*(sp)++; lo=*(sp)++; red   = (png_uint_16)((hi << 8) | (lo));
+               hi=*(sp)++; lo=*(sp)++; green = (png_uint_16)((hi << 8) | (lo));
+               hi=*(sp)++; lo=*(sp)++; blue  = (png_uint_16)((hi << 8) | (lo));
 
                if (red == green && red == blue)
                {
                   if (png_ptr->gamma_16_table != NULL)
-                     w = png_ptr->gamma_16_table[(red&0xff)
-                         >> png_ptr->gamma_shift][red>>8];
+                     w = png_ptr->gamma_16_table[(red & 0xff)
+                         >> png_ptr->gamma_shift][red >> 8];
 
                   else
                      w = red;
@@ -3346,16 +3105,16 @@ png_do_rgb_to_gray(png_structp png_ptr, png_row_infop row_info, png_bytep row)
 
                else
                {
-                  png_uint_16 red_1   = png_ptr->gamma_16_to_1[(red&0xff)
+                  png_uint_16 red_1   = png_ptr->gamma_16_to_1[(red & 0xff)
                       >> png_ptr->gamma_shift][red>>8];
                   png_uint_16 green_1 =
-                      png_ptr->gamma_16_to_1[(green&0xff) >>
+                      png_ptr->gamma_16_to_1[(green & 0xff) >>
                       png_ptr->gamma_shift][green>>8];
-                  png_uint_16 blue_1  = png_ptr->gamma_16_to_1[(blue&0xff)
+                  png_uint_16 blue_1  = png_ptr->gamma_16_to_1[(blue & 0xff)
                       >> png_ptr->gamma_shift][blue>>8];
                   png_uint_16 gray16  = (png_uint_16)((rc*red_1 + gc*green_1
                       + bc*blue_1 + 16384)>>15);
-                  w = png_ptr->gamma_16_from_1[(gray16&0xff) >>
+                  w = png_ptr->gamma_16_from_1[(gray16 & 0xff) >>
                       png_ptr->gamma_shift][gray16 >> 8];
                   rgb_error |= 1;
                }
@@ -3363,7 +3122,7 @@ png_do_rgb_to_gray(png_structp png_ptr, png_row_infop row_info, png_bytep row)
                *(dp++) = (png_byte)((w>>8) & 0xff);
                *(dp++) = (png_byte)(w & 0xff);
 
-               if (have_alpha)
+               if (have_alpha != 0)
                {
                   *(dp++) = *(sp++);
                   *(dp++) = *(sp++);
@@ -3380,10 +3139,11 @@ png_do_rgb_to_gray(png_structp png_ptr, png_row_infop row_info, png_bytep row)
             for (i = 0; i < row_width; i++)
             {
                png_uint_16 red, green, blue, gray16;
+               png_byte hi,lo;
 
-               red   = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
-               green = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
-               blue  = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
+               hi=*(sp)++; lo=*(sp)++; red   = (png_uint_16)((hi << 8) | (lo));
+               hi=*(sp)++; lo=*(sp)++; green = (png_uint_16)((hi << 8) | (lo));
+               hi=*(sp)++; lo=*(sp)++; blue  = (png_uint_16)((hi << 8) | (lo));
 
                if (red != green || red != blue)
                   rgb_error |= 1;
@@ -3394,10 +3154,10 @@ png_do_rgb_to_gray(png_structp png_ptr, png_row_infop row_info, png_bytep row)
                 */
                gray16  = (png_uint_16)((rc*red + gc*green + bc*blue + 16384) >>
                   15);
-               *(dp++) = (png_byte)((gray16>>8) & 0xff);
+               *(dp++) = (png_byte)((gray16 >> 8) & 0xff);
                *(dp++) = (png_byte)(gray16 & 0xff);
 
-               if (have_alpha)
+               if (have_alpha != 0)
                {
                   *(dp++) = *(sp++);
                   *(dp++) = *(sp++);
@@ -3416,74 +3176,15 @@ png_do_rgb_to_gray(png_structp png_ptr, png_row_infop row_info, png_bytep row)
    return rgb_error;
 }
 #endif
-#endif /* PNG_READ_TRANSFORMS_SUPPORTED */
-
-#ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
-/* Build a grayscale palette.  Palette is assumed to be 1 << bit_depth
- * large of png_color.  This lets grayscale images be treated as
- * paletted.  Most useful for gamma correction and simplification
- * of code.  This API is not used internally.
- */
-void PNGAPI
-png_build_grayscale_palette(int bit_depth, png_colorp palette)
-{
-   int num_palette;
-   int color_inc;
-   int i;
-   int v;
-
-   png_debug(1, "in png_do_build_grayscale_palette");
-
-   if (palette == NULL)
-      return;
-
-   switch (bit_depth)
-   {
-      case 1:
-         num_palette = 2;
-         color_inc = 0xff;
-         break;
-
-      case 2:
-         num_palette = 4;
-         color_inc = 0x55;
-         break;
-
-      case 4:
-         num_palette = 16;
-         color_inc = 0x11;
-         break;
-
-      case 8:
-         num_palette = 256;
-         color_inc = 1;
-         break;
-
-      default:
-         num_palette = 0;
-         color_inc = 0;
-         break;
-   }
-
-   for (i = 0, v = 0; i < num_palette; i++, v += color_inc)
-   {
-      palette[i].red = (png_byte)v;
-      palette[i].green = (png_byte)v;
-      palette[i].blue = (png_byte)v;
-   }
-}
-#endif
-
 
-#ifdef PNG_READ_TRANSFORMS_SUPPORTED
-#if (defined PNG_READ_BACKGROUND_SUPPORTED) ||\
-   (defined PNG_READ_ALPHA_MODE_SUPPORTED)
+#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
+   defined(PNG_READ_ALPHA_MODE_SUPPORTED)
 /* Replace any alpha or transparency with the supplied background color.
  * "background" is already in the screen gamma, while "background_1" is
  * at a gamma of 1.0.  Paletted files have already been taken care of.
  */
-void /* PRIVATE */
-png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
+static void
+png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
 {
 #ifdef PNG_READ_GAMMA_SUPPORTED
    png_const_bytep gamma_table = png_ptr->gamma_table;
@@ -3493,12 +3194,12 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
    png_const_uint_16pp gamma_16_from_1 = png_ptr->gamma_16_from_1;
    png_const_uint_16pp gamma_16_to_1 = png_ptr->gamma_16_to_1;
    int gamma_shift = png_ptr->gamma_shift;
+   int optimize = (png_ptr->flags & PNG_FLAG_OPTIMIZE_ALPHA) != 0;
 #endif
 
    png_bytep sp;
    png_uint_32 i;
    png_uint_32 row_width = row_info->width;
-   int optimize = (png_ptr->flags & PNG_FLAG_OPTIMIZE_ALPHA) != 0;
    int shift;
 
    png_debug(1, "in png_do_compose");
@@ -3519,11 +3220,12 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
                      if ((png_uint_16)((*sp >> shift) & 0x01)
                         == png_ptr->trans_color.gray)
                      {
-                        *sp &= (png_byte)((0x7f7f >> (7 - shift)) & 0xff);
-                        *sp |= (png_byte)(png_ptr->background.gray << shift);
+                        unsigned int tmp = *sp & (0x7f7f >> (7 - shift));
+                        tmp |= png_ptr->background.gray << shift;
+                        *sp = (png_byte)(tmp & 0xff);
                      }
 
-                     if (!shift)
+                     if (shift == 0)
                      {
                         shift = 7;
                         sp++;
@@ -3547,20 +3249,22 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
                         if ((png_uint_16)((*sp >> shift) & 0x03)
                             == png_ptr->trans_color.gray)
                         {
-                           *sp &= (png_byte)((0x3f3f >> (6 - shift)) & 0xff);
-                           *sp |= (png_byte)(png_ptr->background.gray << shift);
+                           unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
+                           tmp |= png_ptr->background.gray << shift;
+                           *sp = (png_byte)(tmp & 0xff);
                         }
 
                         else
                         {
-                           png_byte p = (png_byte)((*sp >> shift) & 0x03);
-                           png_byte g = (png_byte)((gamma_table [p | (p << 2) |
-                               (p << 4) | (p << 6)] >> 6) & 0x03);
-                           *sp &= (png_byte)((0x3f3f >> (6 - shift)) & 0xff);
-                           *sp |= (png_byte)(g << shift);
+                           unsigned int p = (*sp >> shift) & 0x03;
+                           unsigned int g = (gamma_table [p | (p << 2) |
+                               (p << 4) | (p << 6)] >> 6) & 0x03;
+                           unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
+                           tmp |= g << shift;
+                           *sp = (png_byte)(tmp & 0xff);
                         }
 
-                        if (!shift)
+                        if (shift == 0)
                         {
                            shift = 6;
                            sp++;
@@ -3581,11 +3285,12 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
                         if ((png_uint_16)((*sp >> shift) & 0x03)
                             == png_ptr->trans_color.gray)
                         {
-                           *sp &= (png_byte)((0x3f3f >> (6 - shift)) & 0xff);
-                           *sp |= (png_byte)(png_ptr->background.gray << shift);
+                           unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
+                           tmp |= png_ptr->background.gray << shift;
+                           *sp = (png_byte)(tmp & 0xff);
                         }
 
-                        if (!shift)
+                        if (shift == 0)
                         {
                            shift = 6;
                            sp++;
@@ -3610,20 +3315,22 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
                         if ((png_uint_16)((*sp >> shift) & 0x0f)
                             == png_ptr->trans_color.gray)
                         {
-                           *sp &= (png_byte)((0xf0f >> (4 - shift)) & 0xff);
-                           *sp |= (png_byte)(png_ptr->background.gray << shift);
+                           unsigned int tmp = *sp & (0xf0f >> (4 - shift));
+                           tmp |= png_ptr->background.gray << shift;
+                           *sp = (png_byte)(tmp & 0xff);
                         }
 
                         else
                         {
-                           png_byte p = (png_byte)((*sp >> shift) & 0x0f);
-                           png_byte g = (png_byte)((gamma_table[p |
-                               (p << 4)] >> 4) & 0x0f);
-                           *sp &= (png_byte)((0xf0f >> (4 - shift)) & 0xff);
-                           *sp |= (png_byte)(g << shift);
+                           unsigned int p = (*sp >> shift) & 0x0f;
+                           unsigned int g = (gamma_table[p | (p << 4)] >> 4) &
+                              0x0f;
+                           unsigned int tmp = *sp & (0xf0f >> (4 - shift));
+                           tmp |= g << shift;
+                           *sp = (png_byte)(tmp & 0xff);
                         }
 
-                        if (!shift)
+                        if (shift == 0)
                         {
                            shift = 4;
                            sp++;
@@ -3644,11 +3351,12 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
                         if ((png_uint_16)((*sp >> shift) & 0x0f)
                             == png_ptr->trans_color.gray)
                         {
-                           *sp &= (png_byte)((0xf0f >> (4 - shift)) & 0xff);
-                           *sp |= (png_byte)(png_ptr->background.gray << shift);
+                           unsigned int tmp = *sp & (0xf0f >> (4 - shift));
+                           tmp |= png_ptr->background.gray << shift;
+                           *sp = (png_byte)(tmp & 0xff);
                         }
 
-                        if (!shift)
+                        if (shift == 0)
                         {
                            shift = 4;
                            sp++;
@@ -3704,8 +3412,10 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
                         if (v == png_ptr->trans_color.gray)
                         {
                            /* Background is already in screen gamma */
-                           *sp = (png_byte)((png_ptr->background.gray >> 8) & 0xff);
-                           *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
+                           *sp = (png_byte)((png_ptr->background.gray >> 8)
+                                & 0xff);
+                           *(sp + 1) = (png_byte)(png_ptr->background.gray
+                                & 0xff);
                         }
 
                         else
@@ -3728,8 +3438,10 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
 
                         if (v == png_ptr->trans_color.gray)
                         {
-                           *sp = (png_byte)((png_ptr->background.gray >> 8) & 0xff);
-                           *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
+                           *sp = (png_byte)((png_ptr->background.gray >> 8)
+                                & 0xff);
+                           *(sp + 1) = (png_byte)(png_ptr->background.gray
+                                & 0xff);
                         }
                      }
                   }
@@ -3809,9 +3521,12 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
                         /* Background is already in screen gamma */
                         *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
                         *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
-                        *(sp + 2) = (png_byte)((png_ptr->background.green >> 8) & 0xff);
-                        *(sp + 3) = (png_byte)(png_ptr->background.green & 0xff);
-                        *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8) & 0xff);
+                        *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
+                                & 0xff);
+                        *(sp + 3) = (png_byte)(png_ptr->background.green
+                                & 0xff);
+                        *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
+                                & 0xff);
                         *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
                      }
 
@@ -3852,9 +3567,12 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
                      {
                         *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
                         *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
-                        *(sp + 2) = (png_byte)((png_ptr->background.green >> 8) & 0xff);
-                        *(sp + 3) = (png_byte)(png_ptr->background.green & 0xff);
-                        *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8) & 0xff);
+                        *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
+                                & 0xff);
+                        *(sp + 3) = (png_byte)(png_ptr->background.green
+                                & 0xff);
+                        *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
+                                & 0xff);
                         *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
                      }
                   }
@@ -3891,7 +3609,7 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
 
                         v = gamma_to_1[*sp];
                         png_composite(w, v, a, png_ptr->background_1.gray);
-                        if (!optimize)
+                        if (optimize == 0)
                            w = gamma_from_1[w];
                         *sp = w;
                      }
@@ -3909,7 +3627,7 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
                         *sp = (png_byte)png_ptr->background.gray;
 
                      else if (a < 0xff)
-                        png_composite(*sp, *sp, a, png_ptr->background_1.gray);
+                        png_composite(*sp, *sp, a, png_ptr->background.gray);
                   }
                }
             }
@@ -3937,7 +3655,8 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
                      else if (a == 0)
                      {
                         /* Background is already in screen gamma */
-                        *sp = (png_byte)((png_ptr->background.gray >> 8) & 0xff);
+                        *sp = (png_byte)((png_ptr->background.gray >> 8)
+                                & 0xff);
                         *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
                      }
 
@@ -3947,10 +3666,11 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
 
                         g = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
                         png_composite_16(v, g, a, png_ptr->background_1.gray);
-                        if (optimize)
+                        if (optimize != 0)
                            w = v;
                         else
-                           w = gamma_16_from_1[(v&0xff) >> gamma_shift][v >> 8];
+                           w = gamma_16_from_1[(v & 0xff) >>
+                               gamma_shift][v >> 8];
                         *sp = (png_byte)((w >> 8) & 0xff);
                         *(sp + 1) = (png_byte)(w & 0xff);
                      }
@@ -3967,7 +3687,8 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
 
                      if (a == 0)
                      {
-                        *sp = (png_byte)((png_ptr->background.gray >> 8) & 0xff);
+                        *sp = (png_byte)((png_ptr->background.gray >> 8)
+                                & 0xff);
                         *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
                      }
 
@@ -3976,7 +3697,7 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
                         png_uint_16 g, v;
 
                         g = (png_uint_16)(((*sp) << 8) + *(sp + 1));
-                        png_composite_16(v, g, a, png_ptr->background_1.gray);
+                        png_composite_16(v, g, a, png_ptr->background.gray);
                         *sp = (png_byte)((v >> 8) & 0xff);
                         *(sp + 1) = (png_byte)(v & 0xff);
                      }
@@ -4020,17 +3741,17 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
 
                         v = gamma_to_1[*sp];
                         png_composite(w, v, a, png_ptr->background_1.red);
-                        if (!optimize) w = gamma_from_1[w];
+                        if (optimize == 0) w = gamma_from_1[w];
                         *sp = w;
 
                         v = gamma_to_1[*(sp + 1)];
                         png_composite(w, v, a, png_ptr->background_1.green);
-                        if (!optimize) w = gamma_from_1[w];
+                        if (optimize == 0) w = gamma_from_1[w];
                         *(sp + 1) = w;
 
                         v = gamma_to_1[*(sp + 2)];
                         png_composite(w, v, a, png_ptr->background_1.blue);
-                        if (!optimize) w = gamma_from_1[w];
+                        if (optimize == 0) w = gamma_from_1[w];
                         *(sp + 2) = w;
                      }
                   }
@@ -4097,9 +3818,12 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
                         /* Background is already in screen gamma */
                         *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
                         *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
-                        *(sp + 2) = (png_byte)((png_ptr->background.green >> 8) & 0xff);
-                        *(sp + 3) = (png_byte)(png_ptr->background.green & 0xff);
-                        *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8) & 0xff);
+                        *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
+                                & 0xff);
+                        *(sp + 3) = (png_byte)(png_ptr->background.green
+                                & 0xff);
+                        *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
+                                & 0xff);
                         *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
                      }
 
@@ -4109,23 +3833,26 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
 
                         v = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
                         png_composite_16(w, v, a, png_ptr->background_1.red);
-                        if (!optimize)
-                           w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >> 8];
+                        if (optimize == 0)
+                           w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >>
+                                8];
                         *sp = (png_byte)((w >> 8) & 0xff);
                         *(sp + 1) = (png_byte)(w & 0xff);
 
                         v = gamma_16_to_1[*(sp + 3) >> gamma_shift][*(sp + 2)];
                         png_composite_16(w, v, a, png_ptr->background_1.green);
-                        if (!optimize)
-                           w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >> 8];
+                        if (optimize == 0)
+                           w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >>
+                                8];
 
                         *(sp + 2) = (png_byte)((w >> 8) & 0xff);
                         *(sp + 3) = (png_byte)(w & 0xff);
 
                         v = gamma_16_to_1[*(sp + 5) >> gamma_shift][*(sp + 4)];
                         png_composite_16(w, v, a, png_ptr->background_1.blue);
-                        if (!optimize)
-                           w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >> 8];
+                        if (optimize == 0)
+                           w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >>
+                                8];
 
                         *(sp + 4) = (png_byte)((w >> 8) & 0xff);
                         *(sp + 5) = (png_byte)(w & 0xff);
@@ -4146,9 +3873,12 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
                      {
                         *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
                         *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
-                        *(sp + 2) = (png_byte)((png_ptr->background.green >> 8) & 0xff);
-                        *(sp + 3) = (png_byte)(png_ptr->background.green & 0xff);
-                        *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8) & 0xff);
+                        *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
+                                & 0xff);
+                        *(sp + 3) = (png_byte)(png_ptr->background.green
+                                & 0xff);
+                        *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
+                                & 0xff);
                         *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
                      }
 
@@ -4185,7 +3915,7 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
       }
    }
 }
-#endif /* PNG_READ_BACKGROUND_SUPPORTED || PNG_READ_ALPHA_MODE_SUPPORTED */
+#endif /* READ_BACKGROUND || READ_ALPHA_MODE */
 
 #ifdef PNG_READ_GAMMA_SUPPORTED
 /* Gamma correct the image, avoiding the alpha channel.  Make sure
@@ -4194,8 +3924,8 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
  * is 16, use gamma_16_table and gamma_shift.  Build these with
  * build_gamma_table().
  */
-void /* PRIVATE */
-png_do_gamma(png_row_infop row_info, png_bytep row, png_structp png_ptr)
+static void
+png_do_gamma(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
 {
    png_const_bytep gamma_table = png_ptr->gamma_table;
    png_const_uint_16pp gamma_16_table = png_ptr->gamma_16_table;
@@ -4395,14 +4125,14 @@ png_do_gamma(png_row_infop row_info, png_bytep row, png_structp png_ptr)
  * linear.)  Called only with color types that have an alpha channel.  Needs the
  * from_1 tables.
  */
-void /* PRIVATE */
-png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structp png_ptr)
+static void
+png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
 {
    png_uint_32 row_width = row_info->width;
 
    png_debug(1, "in png_do_encode_alpha");
 
-   if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
+   if ((row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
    {
       if (row_info->bit_depth == 8)
       {
@@ -4461,7 +4191,7 @@ png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structp png_ptr)
 /* Expands a palette row to an RGB or RGBA row depending
  * upon whether you supply trans and num_trans.
  */
-void /* PRIVATE */
+static void
 png_do_expand_palette(png_row_infop row_info, png_bytep row,
    png_const_colorp palette, png_const_bytep trans_alpha, int num_trans)
 {
@@ -4614,7 +4344,7 @@ png_do_expand_palette(png_row_infop row_info, png_bytep row,
 /* If the bit depth < 8, it is expanded to 8.  Also, if the already
  * expanded transparency value is supplied, an alpha channel is built.
  */
-void /* PRIVATE */
+static void
 png_do_expand(png_row_infop row_info, png_bytep row,
     png_const_color_16p trans_color)
 {
@@ -4628,7 +4358,7 @@ png_do_expand(png_row_infop row_info, png_bytep row,
    {
       if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
       {
-         png_uint_16 gray = (png_uint_16)(trans_color ? trans_color->gray : 0);
+         unsigned int gray = trans_color != NULL ? trans_color->gray : 0;
 
          if (row_info->bit_depth < 8)
          {
@@ -4636,7 +4366,7 @@ png_do_expand(png_row_infop row_info, png_bytep row,
             {
                case 1:
                {
-                  gray = (png_uint_16)((gray & 0x01) * 0xff);
+                  gray = (gray & 0x01) * 0xff;
                   sp = row + (png_size_t)((row_width - 1) >> 3);
                   dp = row + (png_size_t)row_width - 1;
                   shift = 7 - (int)((row_width + 7) & 0x07);
@@ -4664,7 +4394,7 @@ png_do_expand(png_row_infop row_info, png_bytep row,
 
                case 2:
                {
-                  gray = (png_uint_16)((gray & 0x03) * 0x55);
+                  gray = (gray & 0x03) * 0x55;
                   sp = row + (png_size_t)((row_width - 1) >> 2);
                   dp = row + (png_size_t)row_width - 1;
                   shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
@@ -4689,7 +4419,7 @@ png_do_expand(png_row_infop row_info, png_bytep row,
 
                case 4:
                {
-                  gray = (png_uint_16)((gray & 0x0f) * 0x11);
+                  gray = (gray & 0x0f) * 0x11;
                   sp = row + (png_size_t)((row_width - 1) >> 1);
                   dp = row + (png_size_t)row_width - 1;
                   shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
@@ -4742,8 +4472,8 @@ png_do_expand(png_row_infop row_info, png_bytep row,
 
             else if (row_info->bit_depth == 16)
             {
-               png_byte gray_high = (png_byte)((gray >> 8) & 0xff);
-               png_byte gray_low = (png_byte)(gray & 0xff);
+               unsigned int gray_high = (gray >> 8) & 0xff;
+               unsigned int gray_low = gray & 0xff;
                sp = row + row_info->rowbytes - 1;
                dp = row + (row_info->rowbytes << 1) - 1;
                for (i = 0; i < row_width; i++)
@@ -4772,7 +4502,8 @@ png_do_expand(png_row_infop row_info, png_bytep row,
                row_width);
          }
       }
-      else if (row_info->color_type == PNG_COLOR_TYPE_RGB && trans_color)
+      else if (row_info->color_type == PNG_COLOR_TYPE_RGB &&
+          trans_color != NULL)
       {
          if (row_info->bit_depth == 8)
          {
@@ -4844,7 +4575,7 @@ png_do_expand(png_row_infop row_info, png_bytep row,
 /* If the bit depth is 8 and the color type is not a palette type expand the
  * whole row to 16 bits.  Has no effect otherwise.
  */
-void /* PRIVATE */
+static void
 png_do_expand_16(png_row_infop row_info, png_bytep row)
 {
    if (row_info->bit_depth == 8 &&
@@ -4872,7 +4603,7 @@ png_do_expand_16(png_row_infop row_info, png_bytep row)
 #endif
 
 #ifdef PNG_READ_QUANTIZE_SUPPORTED
-void /* PRIVATE */
+static void
 png_do_quantize(png_row_infop row_info, png_bytep row,
     png_const_bytep palette_lookup, png_const_bytep quantize_lookup)
 {
@@ -4963,70 +4694,304 @@ png_do_quantize(png_row_infop row_info, png_bytep row,
       }
    }
 }
-#endif /* PNG_READ_QUANTIZE_SUPPORTED */
-#endif /* PNG_READ_TRANSFORMS_SUPPORTED */
+#endif /* READ_QUANTIZE */
 
-#ifdef PNG_MNG_FEATURES_SUPPORTED
-/* Undoes intrapixel differencing  */
+/* Transform the row.  The order of transformations is significant,
+ * and is very touchy.  If you add a transformation, take care to
+ * decide how it fits in with the other transformations here.
+ */
 void /* PRIVATE */
-png_do_read_intrapixel(png_row_infop row_info, png_bytep row)
+png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
 {
-   png_debug(1, "in png_do_read_intrapixel");
+   png_debug(1, "in png_do_read_transformations");
 
-   if (
-       (row_info->color_type & PNG_COLOR_MASK_COLOR))
+   if (png_ptr->row_buf == NULL)
    {
-      int bytes_per_pixel;
-      png_uint_32 row_width = row_info->width;
+      /* Prior to 1.5.4 this output row/pass where the NULL pointer is, but this
+       * error is incredibly rare and incredibly easy to debug without this
+       * information.
+       */
+      png_error(png_ptr, "NULL row buffer");
+   }
 
-      if (row_info->bit_depth == 8)
-      {
-         png_bytep rp;
-         png_uint_32 i;
+   /* The following is debugging; prior to 1.5.4 the code was never compiled in;
+    * in 1.5.4 PNG_FLAG_DETECT_UNINITIALIZED was added and the macro
+    * PNG_WARN_UNINITIALIZED_ROW removed.  In 1.6 the new flag is set only for
+    * all transformations, however in practice the ROW_INIT always gets done on
+    * demand, if necessary.
+    */
+   if ((png_ptr->flags & PNG_FLAG_DETECT_UNINITIALIZED) != 0 &&
+       (png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
+   {
+      /* Application has failed to call either png_read_start_image() or
+       * png_read_update_info() after setting transforms that expand pixels.
+       * This check added to libpng-1.2.19 (but not enabled until 1.5.4).
+       */
+      png_error(png_ptr, "Uninitialized row");
+   }
 
-         if (row_info->color_type == PNG_COLOR_TYPE_RGB)
-            bytes_per_pixel = 3;
+#ifdef PNG_READ_EXPAND_SUPPORTED
+   if ((png_ptr->transformations & PNG_EXPAND) != 0)
+   {
+      if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
+      {
+         png_do_expand_palette(row_info, png_ptr->row_buf + 1,
+             png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans);
+      }
 
-         else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
-            bytes_per_pixel = 4;
+      else
+      {
+         if (png_ptr->num_trans != 0 &&
+             (png_ptr->transformations & PNG_EXPAND_tRNS) != 0)
+            png_do_expand(row_info, png_ptr->row_buf + 1,
+                &(png_ptr->trans_color));
 
          else
-            return;
-
-         for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
-         {
-            *(rp) = (png_byte)((256 + *rp + *(rp + 1)) & 0xff);
-            *(rp+2) = (png_byte)((256 + *(rp + 2) + *(rp + 1)) & 0xff);
-         }
+            png_do_expand(row_info, png_ptr->row_buf + 1,
+                NULL);
       }
-      else if (row_info->bit_depth == 16)
-      {
-         png_bytep rp;
-         png_uint_32 i;
+   }
+#endif
 
-         if (row_info->color_type == PNG_COLOR_TYPE_RGB)
-            bytes_per_pixel = 6;
+#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
+   if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
+       (png_ptr->transformations & PNG_COMPOSE) == 0 &&
+       (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
+       row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
+      png_do_strip_channel(row_info, png_ptr->row_buf + 1,
+         0 /* at_start == false, because SWAP_ALPHA happens later */);
+#endif
 
-         else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
-            bytes_per_pixel = 8;
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+   if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
+   {
+      int rgb_error =
+          png_do_rgb_to_gray(png_ptr, row_info,
+              png_ptr->row_buf + 1);
 
-         else
-            return;
+      if (rgb_error != 0)
+      {
+         png_ptr->rgb_to_gray_status=1;
+         if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
+             PNG_RGB_TO_GRAY_WARN)
+            png_warning(png_ptr, "png_do_rgb_to_gray found nongray pixel");
 
-         for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
-         {
-            png_uint_32 s0   = (*(rp    ) << 8) | *(rp + 1);
-            png_uint_32 s1   = (*(rp + 2) << 8) | *(rp + 3);
-            png_uint_32 s2   = (*(rp + 4) << 8) | *(rp + 5);
-            png_uint_32 red  = (s0 + s1 + 65536) & 0xffff;
-            png_uint_32 blue = (s2 + s1 + 65536) & 0xffff;
-            *(rp    ) = (png_byte)((red >> 8) & 0xff);
-            *(rp + 1) = (png_byte)(red & 0xff);
-            *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
-            *(rp + 5) = (png_byte)(blue & 0xff);
-         }
+         if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
+             PNG_RGB_TO_GRAY_ERR)
+            png_error(png_ptr, "png_do_rgb_to_gray found nongray pixel");
       }
    }
+#endif
+
+/* From Andreas Dilger e-mail to png-implement, 26 March 1998:
+ *
+ *   In most cases, the "simple transparency" should be done prior to doing
+ *   gray-to-RGB, or you will have to test 3x as many bytes to check if a
+ *   pixel is transparent.  You would also need to make sure that the
+ *   transparency information is upgraded to RGB.
+ *
+ *   To summarize, the current flow is:
+ *   - Gray + simple transparency -> compare 1 or 2 gray bytes and composite
+ *                                   with background "in place" if transparent,
+ *                                   convert to RGB if necessary
+ *   - Gray + alpha -> composite with gray background and remove alpha bytes,
+ *                                   convert to RGB if necessary
+ *
+ *   To support RGB backgrounds for gray images we need:
+ *   - Gray + simple transparency -> convert to RGB + simple transparency,
+ *                                   compare 3 or 6 bytes and composite with
+ *                                   background "in place" if transparent
+ *                                   (3x compare/pixel compared to doing
+ *                                   composite with gray bkgrnd)
+ *   - Gray + alpha -> convert to RGB + alpha, composite with background and
+ *                                   remove alpha bytes (3x float
+ *                                   operations/pixel compared with composite
+ *                                   on gray background)
+ *
+ *  Greg's change will do this.  The reason it wasn't done before is for
+ *  performance, as this increases the per-pixel operations.  If we would check
+ *  in advance if the background was gray or RGB, and position the gray-to-RGB
+ *  transform appropriately, then it would save a lot of work/time.
+ */
+
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
+   /* If gray -> RGB, do so now only if background is non-gray; else do later
+    * for performance reasons
+    */
+   if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0 &&
+       (png_ptr->mode & PNG_BACKGROUND_IS_GRAY) == 0)
+      png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
+#endif
+
+#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
+   defined(PNG_READ_ALPHA_MODE_SUPPORTED)
+   if ((png_ptr->transformations & PNG_COMPOSE) != 0)
+      png_do_compose(row_info, png_ptr->row_buf + 1, png_ptr);
+#endif
+
+#ifdef PNG_READ_GAMMA_SUPPORTED
+   if ((png_ptr->transformations & PNG_GAMMA) != 0 &&
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+      /* Because RGB_TO_GRAY does the gamma transform. */
+      (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0 &&
+#endif
+#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
+   defined(PNG_READ_ALPHA_MODE_SUPPORTED)
+      /* Because PNG_COMPOSE does the gamma transform if there is something to
+       * do (if there is an alpha channel or transparency.)
+       */
+       !((png_ptr->transformations & PNG_COMPOSE) != 0 &&
+       ((png_ptr->num_trans != 0) ||
+       (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)) &&
+#endif
+      /* Because png_init_read_transformations transforms the palette, unless
+       * RGB_TO_GRAY will do the transform.
+       */
+       (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE))
+      png_do_gamma(row_info, png_ptr->row_buf + 1, png_ptr);
+#endif
+
+#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
+   if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
+       (png_ptr->transformations & PNG_COMPOSE) != 0 &&
+       (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
+       row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
+      png_do_strip_channel(row_info, png_ptr->row_buf + 1,
+          0 /* at_start == false, because SWAP_ALPHA happens later */);
+#endif
+
+#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
+   if ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 &&
+       (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
+      png_do_encode_alpha(row_info, png_ptr->row_buf + 1, png_ptr);
+#endif
+
+#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
+   if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0)
+      png_do_scale_16_to_8(row_info, png_ptr->row_buf + 1);
+#endif
+
+#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
+   /* There is no harm in doing both of these because only one has any effect,
+    * by putting the 'scale' option first if the app asks for scale (either by
+    * calling the API or in a TRANSFORM flag) this is what happens.
+    */
+   if ((png_ptr->transformations & PNG_16_TO_8) != 0)
+      png_do_chop(row_info, png_ptr->row_buf + 1);
+#endif
+
+#ifdef PNG_READ_QUANTIZE_SUPPORTED
+   if ((png_ptr->transformations & PNG_QUANTIZE) != 0)
+   {
+      png_do_quantize(row_info, png_ptr->row_buf + 1,
+          png_ptr->palette_lookup, png_ptr->quantize_index);
+
+      if (row_info->rowbytes == 0)
+         png_error(png_ptr, "png_do_quantize returned rowbytes=0");
+   }
+#endif /* READ_QUANTIZE */
+
+#ifdef PNG_READ_EXPAND_16_SUPPORTED
+   /* Do the expansion now, after all the arithmetic has been done.  Notice
+    * that previous transformations can handle the PNG_EXPAND_16 flag if this
+    * is efficient (particularly true in the case of gamma correction, where
+    * better accuracy results faster!)
+    */
+   if ((png_ptr->transformations & PNG_EXPAND_16) != 0)
+      png_do_expand_16(row_info, png_ptr->row_buf + 1);
+#endif
+
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
+   /* NOTE: moved here in 1.5.4 (from much later in this list.) */
+   if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0 &&
+       (png_ptr->mode & PNG_BACKGROUND_IS_GRAY) != 0)
+      png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
+#endif
+
+#ifdef PNG_READ_INVERT_SUPPORTED
+   if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
+      png_do_invert(row_info, png_ptr->row_buf + 1);
+#endif
+
+#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
+   if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
+      png_do_read_invert_alpha(row_info, png_ptr->row_buf + 1);
+#endif
+
+#ifdef PNG_READ_SHIFT_SUPPORTED
+   if ((png_ptr->transformations & PNG_SHIFT) != 0)
+      png_do_unshift(row_info, png_ptr->row_buf + 1,
+          &(png_ptr->shift));
+#endif
+
+#ifdef PNG_READ_PACK_SUPPORTED
+   if ((png_ptr->transformations & PNG_PACK) != 0)
+      png_do_unpack(row_info, png_ptr->row_buf + 1);
+#endif
+
+#ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
+   /* Added at libpng-1.5.10 */
+   if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
+       png_ptr->num_palette_max >= 0)
+      png_do_check_palette_indexes(png_ptr, row_info);
+#endif
+
+#ifdef PNG_READ_BGR_SUPPORTED
+   if ((png_ptr->transformations & PNG_BGR) != 0)
+      png_do_bgr(row_info, png_ptr->row_buf + 1);
+#endif
+
+#ifdef PNG_READ_PACKSWAP_SUPPORTED
+   if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
+      png_do_packswap(row_info, png_ptr->row_buf + 1);
+#endif
+
+#ifdef PNG_READ_FILLER_SUPPORTED
+   if ((png_ptr->transformations & PNG_FILLER) != 0)
+      png_do_read_filler(row_info, png_ptr->row_buf + 1,
+          (png_uint_32)png_ptr->filler, png_ptr->flags);
+#endif
+
+#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
+   if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0)
+      png_do_read_swap_alpha(row_info, png_ptr->row_buf + 1);
+#endif
+
+#ifdef PNG_READ_16BIT_SUPPORTED
+#ifdef PNG_READ_SWAP_SUPPORTED
+   if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
+      png_do_swap(row_info, png_ptr->row_buf + 1);
+#endif
+#endif
+
+#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
+   if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
+   {
+      if (png_ptr->read_user_transform_fn != NULL)
+         (*(png_ptr->read_user_transform_fn)) /* User read transform function */
+             (png_ptr,     /* png_ptr */
+             row_info,     /* row_info: */
+                /*  png_uint_32 width;       width of row */
+                /*  png_size_t rowbytes;     number of bytes in row */
+                /*  png_byte color_type;     color type of pixels */
+                /*  png_byte bit_depth;      bit depth of samples */
+                /*  png_byte channels;       number of channels (1-4) */
+                /*  png_byte pixel_depth;    bits per pixel (depth*channels) */
+             png_ptr->row_buf + 1);    /* start of pixel data for row */
+#ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
+      if (png_ptr->user_transform_depth != 0)
+         row_info->bit_depth = png_ptr->user_transform_depth;
+
+      if (png_ptr->user_transform_channels != 0)
+         row_info->channels = png_ptr->user_transform_channels;
+#endif
+      row_info->pixel_depth = (png_byte)(row_info->bit_depth *
+          row_info->channels);
+
+      row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_info->width);
+   }
+#endif
 }
-#endif /* PNG_MNG_FEATURES_SUPPORTED */
-#endif /* PNG_READ_SUPPORTED */
+
+#endif /* READ_TRANSFORMS */
+#endif /* READ */
diff --git a/src/3rdparty/libpng/pngrutil.c b/src/3rdparty/libpng/pngrutil.c
index aa592cc..6c5c375 100644
--- a/src/3rdparty/libpng/pngrutil.c
+++ b/src/3rdparty/libpng/pngrutil.c
@@ -1,8 +1,8 @@
 
 /* pngrutil.c - utilities to read a PNG file
  *
- * Last changed in libpng 1.5.10 [March 8, 2012]
- * Copyright (c) 1998-2012 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.17 [March 26, 2015]
+ * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
@@ -18,10 +18,8 @@
 
 #ifdef PNG_READ_SUPPORTED
 
-#define png_strtod(p,a,b) strtod(a,b)
-
 png_uint_32 PNGAPI
-png_get_uint_31(png_structp png_ptr, png_const_bytep buf)
+png_get_uint_31(png_const_structrp png_ptr, png_const_bytep buf)
 {
    png_uint_32 uval = png_get_uint_32(buf);
 
@@ -40,7 +38,7 @@ png_get_uint_31(png_structp png_ptr, png_const_bytep buf)
 #define PNG_FIXED_ERROR (-1)
 
 static png_fixed_point /* PRIVATE */
-png_get_fixed_point(png_structp png_ptr, png_const_bytep buf)
+png_get_fixed_point(png_structrp png_ptr, png_const_bytep buf)
 {
    png_uint_32 uval = png_get_uint_32(buf);
 
@@ -110,11 +108,11 @@ png_get_uint_16)(png_const_bytep buf)
    return (png_uint_16)val;
 }
 
-#endif /* PNG_READ_INT_FUNCTIONS_SUPPORTED */
+#endif /* READ_INT_FUNCTIONS */
 
 /* Read and check the PNG file signature */
 void /* PRIVATE */
-png_read_sig(png_structp png_ptr, png_infop info_ptr)
+png_read_sig(png_structrp png_ptr, png_inforp info_ptr)
 {
    png_size_t num_checked, num_to_check;
 
@@ -133,7 +131,7 @@ png_read_sig(png_structp png_ptr, png_infop info_ptr)
    png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
    png_ptr->sig_bytes = 8;
 
-   if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
+   if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check) != 0)
    {
       if (num_checked < 4 &&
           png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
@@ -149,7 +147,7 @@ png_read_sig(png_structp png_ptr, png_infop info_ptr)
  * Put the type name into png_ptr->chunk_name, and return the length.
  */
 png_uint_32 /* PRIVATE */
-png_read_chunk_header(png_structp png_ptr)
+png_read_chunk_header(png_structrp png_ptr)
 {
    png_byte buf[8];
    png_uint_32 length;
@@ -186,7 +184,7 @@ png_read_chunk_header(png_structp png_ptr)
 
 /* Read data, and (optionally) run it through the CRC. */
 void /* PRIVATE */
-png_crc_read(png_structp png_ptr, png_bytep buf, png_size_t length)
+png_crc_read(png_structrp png_ptr, png_bytep buf, png_uint_32 length)
 {
    if (png_ptr == NULL)
       return;
@@ -196,40 +194,40 @@ png_crc_read(png_structp png_ptr, png_bytep buf, png_size_t length)
 }
 
 /* Optionally skip data and then check the CRC.  Depending on whether we
- * are reading a ancillary or critical chunk, and how the program has set
+ * are reading an ancillary or critical chunk, and how the program has set
  * things up, we may calculate the CRC on the data and print a message.
  * Returns '1' if there was a CRC error, '0' otherwise.
  */
 int /* PRIVATE */
-png_crc_finish(png_structp png_ptr, png_uint_32 skip)
+png_crc_finish(png_structrp png_ptr, png_uint_32 skip)
 {
-   png_size_t i;
-   png_size_t istop = png_ptr->zbuf_size;
-
-   for (i = (png_size_t)skip; i > istop; i -= istop)
+   /* The size of the local buffer for inflate is a good guess as to a
+    * reasonable size to use for buffering reads from the application.
+    */
+   while (skip > 0)
    {
-      png_crc_read(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
-   }
+      png_uint_32 len;
+      png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
 
-   if (i)
-   {
-      png_crc_read(png_ptr, png_ptr->zbuf, i);
+      len = (sizeof tmpbuf);
+      if (len > skip)
+         len = skip;
+      skip -= len;
+
+      png_crc_read(png_ptr, tmpbuf, len);
    }
 
-   if (png_crc_error(png_ptr))
+   if (png_crc_error(png_ptr) != 0)
    {
-      if (PNG_CHUNK_ANCILLIARY(png_ptr->chunk_name) ?
-          !(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) :
-          (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE))
+      if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0 ?
+          (png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) == 0 :
+          (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE) != 0)
       {
          png_chunk_warning(png_ptr, "CRC error");
       }
 
       else
-      {
-         png_chunk_benign_error(png_ptr, "CRC error");
-         return (0);
-      }
+         png_chunk_error(png_ptr, "CRC error");
 
       return (1);
    }
@@ -241,13 +239,13 @@ png_crc_finish(png_structp png_ptr, png_uint_32 skip)
  * the data it has read thus far.
  */
 int /* PRIVATE */
-png_crc_error(png_structp png_ptr)
+png_crc_error(png_structrp png_ptr)
 {
    png_byte crc_bytes[4];
    png_uint_32 crc;
    int need_crc = 1;
 
-   if (PNG_CHUNK_ANCILLIARY(png_ptr->chunk_name))
+   if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0)
    {
       if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
           (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
@@ -256,7 +254,7 @@ png_crc_error(png_structp png_ptr)
 
    else /* critical */
    {
-      if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
+      if ((png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) != 0)
          need_crc = 0;
    }
 
@@ -267,7 +265,7 @@ png_crc_error(png_structp png_ptr)
    /* The chunk CRC must be serialized in a single I/O call. */
    png_read_data(png_ptr, crc_bytes, 4);
 
-   if (need_crc)
+   if (need_crc != 0)
    {
       crc = png_get_uint_32(crc_bytes);
       return ((int)(crc != png_ptr->crc));
@@ -277,248 +275,522 @@ png_crc_error(png_structp png_ptr)
       return (0);
 }
 
-#ifdef PNG_READ_COMPRESSED_TEXT_SUPPORTED
-static png_size_t
-png_inflate(png_structp png_ptr, png_bytep data, png_size_t size,
-    png_bytep output, png_size_t output_size)
+#if defined(PNG_READ_iCCP_SUPPORTED) || defined(PNG_READ_iTXt_SUPPORTED) ||\
+    defined(PNG_READ_pCAL_SUPPORTED) || defined(PNG_READ_sCAL_SUPPORTED) ||\
+    defined(PNG_READ_sPLT_SUPPORTED) || defined(PNG_READ_tEXt_SUPPORTED) ||\
+    defined(PNG_READ_zTXt_SUPPORTED) || defined(PNG_SEQUENTIAL_READ_SUPPORTED)
+/* Manage the read buffer; this simply reallocates the buffer if it is not small
+ * enough (or if it is not allocated).  The routine returns a pointer to the
+ * buffer; if an error occurs and 'warn' is set the routine returns NULL, else
+ * it will call png_error (via png_malloc) on failure.  (warn == 2 means
+ * 'silent').
+ */
+static png_bytep
+png_read_buffer(png_structrp png_ptr, png_alloc_size_t new_size, int warn)
 {
-   png_size_t count = 0;
-
-   /* zlib can't necessarily handle more than 65535 bytes at once (i.e. it can't
-    * even necessarily handle 65536 bytes) because the type uInt is "16 bits or
-    * more".  Consequently it is necessary to chunk the input to zlib.  This
-    * code uses ZLIB_IO_MAX, from pngpriv.h, as the maximum (the maximum value
-    * that can be stored in a uInt.)  It is possible to set ZLIB_IO_MAX to a
-    * lower value in pngpriv.h and this may sometimes have a performance
-    * advantage, because it forces access of the input data to be separated from
-    * at least some of the use by some period of time.
-    */
-   png_ptr->zstream.next_in = data;
-   /* avail_in is set below from 'size' */
-   png_ptr->zstream.avail_in = 0;
+   png_bytep buffer = png_ptr->read_buffer;
 
-   while (1)
+   if (buffer != NULL && new_size > png_ptr->read_buffer_size)
    {
-      int ret, avail;
+      png_ptr->read_buffer = NULL;
+      png_ptr->read_buffer = NULL;
+      png_ptr->read_buffer_size = 0;
+      png_free(png_ptr, buffer);
+      buffer = NULL;
+   }
 
-      /* The setting of 'avail_in' used to be outside the loop; by setting it
-       * inside it is possible to chunk the input to zlib and simply rely on
-       * zlib to advance the 'next_in' pointer.  This allows arbitrary amounts o
-       * data to be passed through zlib at the unavoidable cost of requiring a
-       * window save (memcpy of up to 32768 output bytes) every ZLIB_IO_MAX
-       * input bytes.
-       */
-      if (png_ptr->zstream.avail_in == 0 && size > 0)
+   if (buffer == NULL)
+   {
+      buffer = png_voidcast(png_bytep, png_malloc_base(png_ptr, new_size));
+
+      if (buffer != NULL)
       {
-         if (size <= ZLIB_IO_MAX)
-         {
-            /* The value is less than ZLIB_IO_MAX so the cast is safe: */
-            png_ptr->zstream.avail_in = (uInt)size;
-            size = 0;
-         }
+         png_ptr->read_buffer = buffer;
+         png_ptr->read_buffer_size = new_size;
+      }
+
+      else if (warn < 2) /* else silent */
+      {
+         if (warn != 0)
+             png_chunk_warning(png_ptr, "insufficient memory to read chunk");
 
          else
-         {
-            png_ptr->zstream.avail_in = ZLIB_IO_MAX;
-            size -= ZLIB_IO_MAX;
-         }
+             png_chunk_error(png_ptr, "insufficient memory to read chunk");
       }
+   }
 
-      /* Reset the output buffer each time round - we empty it
-       * after every inflate call.
+   return buffer;
+}
+#endif /* READ_iCCP|iTXt|pCAL|sCAL|sPLT|tEXt|zTXt|SEQUENTIAL_READ */
+
+/* png_inflate_claim: claim the zstream for some nefarious purpose that involves
+ * decompression.  Returns Z_OK on success, else a zlib error code.  It checks
+ * the owner but, in final release builds, just issues a warning if some other
+ * chunk apparently owns the stream.  Prior to release it does a png_error.
+ */
+static int
+png_inflate_claim(png_structrp png_ptr, png_uint_32 owner)
+{
+   if (png_ptr->zowner != 0)
+   {
+      char msg[64];
+
+      PNG_STRING_FROM_CHUNK(msg, png_ptr->zowner);
+      /* So the message that results is "<chunk> using zstream"; this is an
+       * internal error, but is very useful for debugging.  i18n requirements
+       * are minimal.
        */
-      png_ptr->zstream.next_out = png_ptr->zbuf;
-      png_ptr->zstream.avail_out = png_ptr->zbuf_size;
+      (void)png_safecat(msg, (sizeof msg), 4, " using zstream");
+#if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC
+      png_chunk_warning(png_ptr, msg);
+      png_ptr->zowner = 0;
+#else
+      png_chunk_error(png_ptr, msg);
+#endif
+   }
 
-      ret = inflate(&png_ptr->zstream, Z_NO_FLUSH);
-      avail = png_ptr->zbuf_size - png_ptr->zstream.avail_out;
+   /* Implementation note: unlike 'png_deflate_claim' this internal function
+    * does not take the size of the data as an argument.  Some efficiency could
+    * be gained by using this when it is known *if* the zlib stream itself does
+    * not record the number; however, this is an illusion: the original writer
+    * of the PNG may have selected a lower window size, and we really must
+    * follow that because, for systems with with limited capabilities, we
+    * would otherwise reject the application's attempts to use a smaller window
+    * size (zlib doesn't have an interface to say "this or lower"!).
+    *
+    * inflateReset2 was added to zlib 1.2.4; before this the window could not be
+    * reset, therefore it is necessary to always allocate the maximum window
+    * size with earlier zlibs just in case later compressed chunks need it.
+    */
+   {
+      int ret; /* zlib return code */
+#if PNG_ZLIB_VERNUM >= 0x1240
 
-      /* First copy/count any new output - but only if we didn't
-       * get an error code.
+# if defined(PNG_SET_OPTION_SUPPORTED) && defined(PNG_MAXIMUM_INFLATE_WINDOW)
+      int window_bits;
+
+      if (((png_ptr->options >> PNG_MAXIMUM_INFLATE_WINDOW) & 3) ==
+          PNG_OPTION_ON)
+         window_bits = 15;
+
+      else
+         window_bits = 0;
+# else
+#   define window_bits 0
+# endif
+#endif
+
+      /* Set this for safety, just in case the previous owner left pointers to
+       * memory allocations.
        */
-      if ((ret == Z_OK || ret == Z_STREAM_END) && avail > 0)
-      {
-         png_size_t space = avail; /* > 0, see above */
+      png_ptr->zstream.next_in = NULL;
+      png_ptr->zstream.avail_in = 0;
+      png_ptr->zstream.next_out = NULL;
+      png_ptr->zstream.avail_out = 0;
 
-         if (output != 0 && output_size > count)
-         {
-            png_size_t copy = output_size - count;
+      if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
+      {
+#if PNG_ZLIB_VERNUM < 0x1240
+         ret = inflateReset(&png_ptr->zstream);
+#else
+         ret = inflateReset2(&png_ptr->zstream, window_bits);
+#endif
+      }
 
-            if (space < copy)
-               copy = space;
+      else
+      {
+#if PNG_ZLIB_VERNUM < 0x1240
+         ret = inflateInit(&png_ptr->zstream);
+#else
+         ret = inflateInit2(&png_ptr->zstream, window_bits);
+#endif
 
-            png_memcpy(output + count, png_ptr->zbuf, copy);
-         }
-         count += space;
+         if (ret == Z_OK)
+            png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
       }
 
       if (ret == Z_OK)
-         continue;
+         png_ptr->zowner = owner;
+
+      else
+         png_zstream_error(png_ptr, ret);
+
+      return ret;
+   }
+
+#ifdef window_bits
+# undef window_bits
+#endif
+}
 
-      /* Termination conditions - always reset the zstream, it
-       * must be left in inflateInit state.
+#ifdef PNG_READ_COMPRESSED_TEXT_SUPPORTED
+/* png_inflate now returns zlib error codes including Z_OK and Z_STREAM_END to
+ * allow the caller to do multiple calls if required.  If the 'finish' flag is
+ * set Z_FINISH will be passed to the final inflate() call and Z_STREAM_END must
+ * be returned or there has been a problem, otherwise Z_SYNC_FLUSH is used and
+ * Z_OK or Z_STREAM_END will be returned on success.
+ *
+ * The input and output sizes are updated to the actual amounts of data consumed
+ * or written, not the amount available (as in a z_stream).  The data pointers
+ * are not changed, so the next input is (data+input_size) and the next
+ * available output is (output+output_size).
+ */
+static int
+png_inflate(png_structrp png_ptr, png_uint_32 owner, int finish,
+    /* INPUT: */ png_const_bytep input, png_uint_32p input_size_ptr,
+    /* OUTPUT: */ png_bytep output, png_alloc_size_t *output_size_ptr)
+{
+   if (png_ptr->zowner == owner) /* Else not claimed */
+   {
+      int ret;
+      png_alloc_size_t avail_out = *output_size_ptr;
+      png_uint_32 avail_in = *input_size_ptr;
+
+      /* zlib can't necessarily handle more than 65535 bytes at once (i.e. it
+       * can't even necessarily handle 65536 bytes) because the type uInt is
+       * "16 bits or more".  Consequently it is necessary to chunk the input to
+       * zlib.  This code uses ZLIB_IO_MAX, from pngpriv.h, as the maximum (the
+       * maximum value that can be stored in a uInt.)  It is possible to set
+       * ZLIB_IO_MAX to a lower value in pngpriv.h and this may sometimes have
+       * a performance advantage, because it reduces the amount of data accessed
+       * at each step and that may give the OS more time to page it in.
        */
+      png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input);
+      /* avail_in and avail_out are set below from 'size' */
       png_ptr->zstream.avail_in = 0;
-      inflateReset(&png_ptr->zstream);
-
-      if (ret == Z_STREAM_END)
-         return count; /* NOTE: may be zero. */
+      png_ptr->zstream.avail_out = 0;
 
-      /* Now handle the error codes - the API always returns 0
-       * and the error message is dumped into the uncompressed
-       * buffer if available.
+      /* Read directly into the output if it is available (this is set to
+       * a local buffer below if output is NULL).
        */
-#     ifdef PNG_WARNINGS_SUPPORTED
+      if (output != NULL)
+         png_ptr->zstream.next_out = output;
+
+      do
       {
-         png_const_charp msg;
+         uInt avail;
+         Byte local_buffer[PNG_INFLATE_BUF_SIZE];
+
+         /* zlib INPUT BUFFER */
+         /* The setting of 'avail_in' used to be outside the loop; by setting it
+          * inside it is possible to chunk the input to zlib and simply rely on
+          * zlib to advance the 'next_in' pointer.  This allows arbitrary
+          * amounts of data to be passed through zlib at the unavoidable cost of
+          * requiring a window save (memcpy of up to 32768 output bytes)
+          * every ZLIB_IO_MAX input bytes.
+          */
+         avail_in += png_ptr->zstream.avail_in; /* not consumed last time */
 
-         if (png_ptr->zstream.msg != 0)
-            msg = png_ptr->zstream.msg;
+         avail = ZLIB_IO_MAX;
 
-         else switch (ret)
-         {
-            case Z_BUF_ERROR:
-               msg = "Buffer error in compressed datastream";
-               break;
+         if (avail_in < avail)
+            avail = (uInt)avail_in; /* safe: < than ZLIB_IO_MAX */
 
-            case Z_DATA_ERROR:
-               msg = "Data error in compressed datastream";
-               break;
+         avail_in -= avail;
+         png_ptr->zstream.avail_in = avail;
 
-            default:
-               msg = "Incomplete compressed datastream";
-               break;
+         /* zlib OUTPUT BUFFER */
+         avail_out += png_ptr->zstream.avail_out; /* not written last time */
+
+         avail = ZLIB_IO_MAX; /* maximum zlib can process */
+
+         if (output == NULL)
+         {
+            /* Reset the output buffer each time round if output is NULL and
+             * make available the full buffer, up to 'remaining_space'
+             */
+            png_ptr->zstream.next_out = local_buffer;
+            if ((sizeof local_buffer) < avail)
+               avail = (sizeof local_buffer);
          }
 
-         png_chunk_warning(png_ptr, msg);
-      }
-#     endif
+         if (avail_out < avail)
+            avail = (uInt)avail_out; /* safe: < ZLIB_IO_MAX */
 
-      /* 0 means an error - notice that this code simply ignores
-       * zero length compressed chunks as a result.
+         png_ptr->zstream.avail_out = avail;
+         avail_out -= avail;
+
+         /* zlib inflate call */
+         /* In fact 'avail_out' may be 0 at this point, that happens at the end
+          * of the read when the final LZ end code was not passed at the end of
+          * the previous chunk of input data.  Tell zlib if we have reached the
+          * end of the output buffer.
+          */
+         ret = inflate(&png_ptr->zstream, avail_out > 0 ? Z_NO_FLUSH :
+             (finish ? Z_FINISH : Z_SYNC_FLUSH));
+      } while (ret == Z_OK);
+
+      /* For safety kill the local buffer pointer now */
+      if (output == NULL)
+         png_ptr->zstream.next_out = NULL;
+
+      /* Claw back the 'size' and 'remaining_space' byte counts. */
+      avail_in += png_ptr->zstream.avail_in;
+      avail_out += png_ptr->zstream.avail_out;
+
+      /* Update the input and output sizes; the updated values are the amount
+       * consumed or written, effectively the inverse of what zlib uses.
        */
-      return 0;
+      if (avail_out > 0)
+         *output_size_ptr -= avail_out;
+
+      if (avail_in > 0)
+         *input_size_ptr -= avail_in;
+
+      /* Ensure png_ptr->zstream.msg is set (even in the success case!) */
+      png_zstream_error(png_ptr, ret);
+      return ret;
+   }
+
+   else
+   {
+      /* This is a bad internal error.  The recovery assigns to the zstream msg
+       * pointer, which is not owned by the caller, but this is safe; it's only
+       * used on errors!
+       */
+      png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
+      return Z_STREAM_ERROR;
    }
 }
 
 /*
- * Decompress trailing data in a chunk.  The assumption is that chunkdata
+ * Decompress trailing data in a chunk.  The assumption is that read_buffer
  * points at an allocated area holding the contents of a chunk with a
  * trailing compressed part.  What we get back is an allocated area
  * holding the original prefix part and an uncompressed version of the
  * trailing part (the malloc area passed in is freed).
  */
-void /* PRIVATE */
-png_decompress_chunk(png_structp png_ptr, int comp_type,
-    png_size_t chunklength,
-    png_size_t prefix_size, png_size_t *newlength)
+static int
+png_decompress_chunk(png_structrp png_ptr,
+   png_uint_32 chunklength, png_uint_32 prefix_size,
+   png_alloc_size_t *newlength /* must be initialized to the maximum! */,
+   int terminate /*add a '\0' to the end of the uncompressed data*/)
 {
-   /* The caller should guarantee this */
-   if (prefix_size > chunklength)
-   {
-      /* The recovery is to delete the chunk. */
-      png_warning(png_ptr, "invalid chunklength");
-      prefix_size = 0; /* To delete everything */
-   }
+   /* TODO: implement different limits for different types of chunk.
+    *
+    * The caller supplies *newlength set to the maximum length of the
+    * uncompressed data, but this routine allocates space for the prefix and
+    * maybe a '\0' terminator too.  We have to assume that 'prefix_size' is
+    * limited only by the maximum chunk size.
+    */
+   png_alloc_size_t limit = PNG_SIZE_MAX;
 
-   else if (comp_type == PNG_COMPRESSION_TYPE_BASE)
+# ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
+   if (png_ptr->user_chunk_malloc_max > 0 &&
+       png_ptr->user_chunk_malloc_max < limit)
+      limit = png_ptr->user_chunk_malloc_max;
+# elif PNG_USER_CHUNK_MALLOC_MAX > 0
+   if (PNG_USER_CHUNK_MALLOC_MAX < limit)
+      limit = PNG_USER_CHUNK_MALLOC_MAX;
+# endif
+
+   if (limit >= prefix_size + (terminate != 0))
    {
-      png_size_t expanded_size = png_inflate(png_ptr,
-          (png_bytep)(png_ptr->chunkdata + prefix_size),
-          chunklength - prefix_size,
-          0,            /* output */
-          0);           /* output size */
+      int ret;
 
-      /* Now check the limits on this chunk - if the limit fails the
-       * compressed data will be removed, the prefix will remain.
-       */
-      if (prefix_size >= (~(png_size_t)0) - 1 ||
-         expanded_size >= (~(png_size_t)0) - 1 - prefix_size
-#ifdef PNG_USER_LIMITS_SUPPORTED
-         || (png_ptr->user_chunk_malloc_max &&
-          (prefix_size + expanded_size >= png_ptr->user_chunk_malloc_max - 1))
-#else
-         || ((PNG_USER_CHUNK_MALLOC_MAX > 0) &&
-          prefix_size + expanded_size >= PNG_USER_CHUNK_MALLOC_MAX - 1)
-#endif
-         )
-         png_warning(png_ptr, "Exceeded size limit while expanding chunk");
+      limit -= prefix_size + (terminate != 0);
 
-      /* If the size is zero either there was an error and a message
-       * has already been output (warning) or the size really is zero
-       * and we have nothing to do - the code will exit through the
-       * error case below.
-       */
-      else if (expanded_size > 0)
+      if (limit < *newlength)
+         *newlength = limit;
+
+      /* Now try to claim the stream. */
+      ret = png_inflate_claim(png_ptr, png_ptr->chunk_name);
+
+      if (ret == Z_OK)
       {
-         /* Success (maybe) - really uncompress the chunk. */
-         png_size_t new_size = 0;
-         png_charp text = (png_charp)png_malloc_warn(png_ptr,
-             prefix_size + expanded_size + 1);
+         png_uint_32 lzsize = chunklength - prefix_size;
+
+         ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
+            /* input: */ png_ptr->read_buffer + prefix_size, &lzsize,
+            /* output: */ NULL, newlength);
 
-         if (text != NULL)
+         if (ret == Z_STREAM_END)
          {
-            png_memcpy(text, png_ptr->chunkdata, prefix_size);
-            new_size = png_inflate(png_ptr,
-                (png_bytep)(png_ptr->chunkdata + prefix_size),
-                chunklength - prefix_size,
-                (png_bytep)(text + prefix_size), expanded_size);
-            text[prefix_size + expanded_size] = 0; /* just in case */
-
-            if (new_size == expanded_size)
+            /* Use 'inflateReset' here, not 'inflateReset2' because this
+             * preserves the previously decided window size (otherwise it would
+             * be necessary to store the previous window size.)  In practice
+             * this doesn't matter anyway, because png_inflate will call inflate
+             * with Z_FINISH in almost all cases, so the window will not be
+             * maintained.
+             */
+            if (inflateReset(&png_ptr->zstream) == Z_OK)
             {
-               png_free(png_ptr, png_ptr->chunkdata);
-               png_ptr->chunkdata = text;
-               *newlength = prefix_size + expanded_size;
-               return; /* The success return! */
+               /* Because of the limit checks above we know that the new,
+                * expanded, size will fit in a size_t (let alone an
+                * png_alloc_size_t).  Use png_malloc_base here to avoid an
+                * extra OOM message.
+                */
+               png_alloc_size_t new_size = *newlength;
+               png_alloc_size_t buffer_size = prefix_size + new_size +
+                  (terminate != 0);
+               png_bytep text = png_voidcast(png_bytep, png_malloc_base(png_ptr,
+                  buffer_size));
+
+               if (text != NULL)
+               {
+                  ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
+                     png_ptr->read_buffer + prefix_size, &lzsize,
+                     text + prefix_size, newlength);
+
+                  if (ret == Z_STREAM_END)
+                  {
+                     if (new_size == *newlength)
+                     {
+                        if (terminate != 0)
+                           text[prefix_size + *newlength] = 0;
+
+                        if (prefix_size > 0)
+                           memcpy(text, png_ptr->read_buffer, prefix_size);
+
+                        {
+                           png_bytep old_ptr = png_ptr->read_buffer;
+
+                           png_ptr->read_buffer = text;
+                           png_ptr->read_buffer_size = buffer_size;
+                           text = old_ptr; /* freed below */
+                        }
+                     }
+
+                     else
+                     {
+                        /* The size changed on the second read, there can be no
+                         * guarantee that anything is correct at this point.
+                         * The 'msg' pointer has been set to "unexpected end of
+                         * LZ stream", which is fine, but return an error code
+                         * that the caller won't accept.
+                         */
+                        ret = PNG_UNEXPECTED_ZLIB_RETURN;
+                     }
+                  }
+
+                  else if (ret == Z_OK)
+                     ret = PNG_UNEXPECTED_ZLIB_RETURN; /* for safety */
+
+                  /* Free the text pointer (this is the old read_buffer on
+                   * success)
+                   */
+                  png_free(png_ptr, text);
+                  text = NULL;
+
+                  /* This really is very benign, but it's still an error because
+                   * the extra space may otherwise be used as a Trojan Horse.
+                   */
+                  if (ret == Z_STREAM_END &&
+                     chunklength - prefix_size != lzsize)
+                     png_chunk_benign_error(png_ptr, "extra compressed data");
+               }
+
+               else
+               {
+                  /* Out of memory allocating the buffer */
+                  ret = Z_MEM_ERROR;
+                  png_zstream_error(png_ptr, Z_MEM_ERROR);
+               }
             }
 
-            png_warning(png_ptr, "png_inflate logic error");
-            png_free(png_ptr, text);
+            else
+            {
+               /* inflateReset failed, store the error message */
+               png_zstream_error(png_ptr, ret);
+
+               if (ret == Z_STREAM_END)
+                  ret = PNG_UNEXPECTED_ZLIB_RETURN;
+            }
          }
 
-         else
-            png_warning(png_ptr, "Not enough memory to decompress chunk");
+         else if (ret == Z_OK)
+            ret = PNG_UNEXPECTED_ZLIB_RETURN;
+
+         /* Release the claimed stream */
+         png_ptr->zowner = 0;
       }
+
+      else /* the claim failed */ if (ret == Z_STREAM_END) /* impossible! */
+         ret = PNG_UNEXPECTED_ZLIB_RETURN;
+
+      return ret;
    }
 
-   else /* if (comp_type != PNG_COMPRESSION_TYPE_BASE) */
+   else
    {
-      PNG_WARNING_PARAMETERS(p)
-      png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_d, comp_type);
-      png_formatted_warning(png_ptr, p, "Unknown compression type @1");
-
-      /* The recovery is to simply drop the data. */
+      /* Application/configuration limits exceeded */
+      png_zstream_error(png_ptr, Z_MEM_ERROR);
+      return Z_MEM_ERROR;
    }
+}
+#endif /* READ_COMPRESSED_TEXT */
 
-   /* Generic error return - leave the prefix, delete the compressed
-    * data, reallocate the chunkdata to remove the potentially large
-    * amount of compressed data.
-    */
+#ifdef PNG_READ_iCCP_SUPPORTED
+/* Perform a partial read and decompress, producing 'avail_out' bytes and
+ * reading from the current chunk as required.
+ */
+static int
+png_inflate_read(png_structrp png_ptr, png_bytep read_buffer, uInt read_size,
+   png_uint_32p chunk_bytes, png_bytep next_out, png_alloc_size_t *out_size,
+   int finish)
+{
+   if (png_ptr->zowner == png_ptr->chunk_name)
    {
-      png_charp text = (png_charp)png_malloc_warn(png_ptr, prefix_size + 1);
+      int ret;
+
+      /* next_in and avail_in must have been initialized by the caller. */
+      png_ptr->zstream.next_out = next_out;
+      png_ptr->zstream.avail_out = 0; /* set in the loop */
 
-      if (text != NULL)
+      do
       {
-         if (prefix_size > 0)
-            png_memcpy(text, png_ptr->chunkdata, prefix_size);
+         if (png_ptr->zstream.avail_in == 0)
+         {
+            if (read_size > *chunk_bytes)
+               read_size = (uInt)*chunk_bytes;
+            *chunk_bytes -= read_size;
+
+            if (read_size > 0)
+               png_crc_read(png_ptr, read_buffer, read_size);
+
+            png_ptr->zstream.next_in = read_buffer;
+            png_ptr->zstream.avail_in = read_size;
+         }
+
+         if (png_ptr->zstream.avail_out == 0)
+         {
+            uInt avail = ZLIB_IO_MAX;
+            if (avail > *out_size)
+               avail = (uInt)*out_size;
+            *out_size -= avail;
 
-         png_free(png_ptr, png_ptr->chunkdata);
-         png_ptr->chunkdata = text;
+            png_ptr->zstream.avail_out = avail;
+         }
 
-         /* This is an extra zero in the 'uncompressed' part. */
-         *(png_ptr->chunkdata + prefix_size) = 0x00;
+         /* Use Z_SYNC_FLUSH when there is no more chunk data to ensure that all
+          * the available output is produced; this allows reading of truncated
+          * streams.
+          */
+         ret = inflate(&png_ptr->zstream,
+            *chunk_bytes > 0 ? Z_NO_FLUSH : (finish ? Z_FINISH : Z_SYNC_FLUSH));
       }
-      /* Ignore a malloc error here - it is safe. */
+      while (ret == Z_OK && (*out_size > 0 || png_ptr->zstream.avail_out > 0));
+
+      *out_size += png_ptr->zstream.avail_out;
+      png_ptr->zstream.avail_out = 0; /* Should not be required, but is safe */
+
+      /* Ensure the error message pointer is always set: */
+      png_zstream_error(png_ptr, ret);
+      return ret;
    }
 
-   *newlength = prefix_size;
+   else
+   {
+      png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
+      return Z_STREAM_ERROR;
+   }
 }
-#endif /* PNG_READ_COMPRESSED_TEXT_SUPPORTED */
+#endif
 
 /* Read and check the IDHR chunk */
+
 void /* PRIVATE */
-png_handle_IHDR(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    png_byte buf[13];
    png_uint_32 width, height;
@@ -527,12 +799,12 @@ png_handle_IHDR(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    png_debug(1, "in png_handle_IHDR");
 
-   if (png_ptr->mode & PNG_HAVE_IHDR)
-      png_error(png_ptr, "Out of place IHDR");
+   if ((png_ptr->mode & PNG_HAVE_IHDR) != 0)
+      png_chunk_error(png_ptr, "out of place");
 
    /* Check the length */
    if (length != 13)
-      png_error(png_ptr, "Invalid IHDR chunk");
+      png_chunk_error(png_ptr, "invalid");
 
    png_ptr->mode |= PNG_HAVE_IHDR;
 
@@ -581,8 +853,7 @@ png_handle_IHDR(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 
    /* Set up other useful info */
-   png_ptr->pixel_depth = (png_byte)(png_ptr->bit_depth *
-   png_ptr->channels);
+   png_ptr->pixel_depth = (png_byte)(png_ptr->bit_depth * png_ptr->channels);
    png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->width);
    png_debug1(3, "bit_depth = %d", png_ptr->bit_depth);
    png_debug1(3, "channels = %d", png_ptr->channels);
@@ -593,7 +864,7 @@ png_handle_IHDR(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
 /* Read and check the palette */
 void /* PRIVATE */
-png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    png_color palette[PNG_MAX_PALETTE_LENGTH];
    int num, i;
@@ -603,26 +874,33 @@ png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    png_debug(1, "in png_handle_PLTE");
 
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before PLTE");
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
+      png_chunk_error(png_ptr, "missing IHDR");
 
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   /* Moved to before the 'after IDAT' check below because otherwise duplicate
+    * PLTE chunks are potentially ignored (the spec says there shall not be more
+    * than one PLTE, the error is not treated as benign, so this check trumps
+    * the requirement that PLTE appears before IDAT.)
+    */
+   else if ((png_ptr->mode & PNG_HAVE_PLTE) != 0)
+      png_chunk_error(png_ptr, "duplicate");
+
+   else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
    {
-      png_warning(png_ptr, "Invalid PLTE after IDAT");
+      /* This is benign because the non-benign error happened before, when an
+       * IDAT was encountered in a color-mapped image with no PLTE.
+       */
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
 
-   else if (png_ptr->mode & PNG_HAVE_PLTE)
-      png_error(png_ptr, "Duplicate PLTE chunk");
-
    png_ptr->mode |= PNG_HAVE_PLTE;
 
-   if (!(png_ptr->color_type&PNG_COLOR_MASK_COLOR))
+   if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
    {
-      png_warning(png_ptr,
-          "Ignoring PLTE chunk in grayscale PNG");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "ignored in grayscale PNG");
       return;
    }
 
@@ -636,19 +914,18 @@ png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    if (length > 3*PNG_MAX_PALETTE_LENGTH || length % 3)
    {
+      png_crc_finish(png_ptr, length);
+
       if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
-      {
-         png_warning(png_ptr, "Invalid palette chunk");
-         png_crc_finish(png_ptr, length);
-         return;
-      }
+         png_chunk_benign_error(png_ptr, "invalid");
 
       else
-      {
-         png_error(png_ptr, "Invalid palette chunk");
-      }
+         png_chunk_error(png_ptr, "invalid");
+
+      return;
    }
 
+   /* The cast is safe because 'length' is less than 3*PNG_MAX_PALETTE_LENGTH */
    num = (int)length / 3;
 
 #ifdef PNG_POINTER_INDEXING_SUPPORTED
@@ -687,214 +964,196 @@ png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 
 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
-   else if (png_crc_error(png_ptr))  /* Only if we have a CRC error */
+   else if (png_crc_error(png_ptr) != 0)  /* Only if we have a CRC error */
    {
       /* If we don't want to use the data from an ancillary chunk,
        * we have two options: an error abort, or a warning and we
        * ignore the data in this chunk (which should be OK, since
        * it's considered ancillary for a RGB or RGBA image).
+       *
+       * IMPLEMENTATION NOTE: this is only here because png_crc_finish uses the
+       * chunk type to determine whether to check the ancillary or the critical
+       * flags.
        */
-      if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE))
+      if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE) == 0)
       {
-         if (png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)
-         {
-            png_chunk_benign_error(png_ptr, "CRC error");
-         }
+         if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) != 0)
+            return;
 
          else
-         {
-            png_chunk_warning(png_ptr, "CRC error");
-            return;
-         }
+            png_chunk_error(png_ptr, "CRC error");
       }
 
       /* Otherwise, we (optionally) emit a warning and use the chunk. */
-      else if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN))
-      {
+      else if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) == 0)
          png_chunk_warning(png_ptr, "CRC error");
-      }
    }
 #endif
 
+   /* TODO: png_set_PLTE has the side effect of setting png_ptr->palette to its
+    * own copy of the palette.  This has the side effect that when png_start_row
+    * is called (this happens after any call to png_read_update_info) the
+    * info_ptr palette gets changed.  This is extremely unexpected and
+    * confusing.
+    *
+    * Fix this by not sharing the palette in this way.
+    */
    png_set_PLTE(png_ptr, info_ptr, palette, num);
 
+   /* The three chunks, bKGD, hIST and tRNS *must* appear after PLTE and before
+    * IDAT.  Prior to 1.6.0 this was not checked; instead the code merely
+    * checked the apparent validity of a tRNS chunk inserted before PLTE on a
+    * palette PNG.  1.6.0 attempts to rigorously follow the standard and
+    * therefore does a benign error if the erroneous condition is detected *and*
+    * cancels the tRNS if the benign error returns.  The alternative is to
+    * amend the standard since it would be rather hypocritical of the standards
+    * maintainers to ignore it.
+    */
 #ifdef PNG_READ_tRNS_SUPPORTED
-   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+   if (png_ptr->num_trans > 0 ||
+       (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0))
    {
-      if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
-      {
-         if (png_ptr->num_trans > (png_uint_16)num)
-         {
-            png_warning(png_ptr, "Truncating incorrect tRNS chunk length");
-            png_ptr->num_trans = (png_uint_16)num;
-         }
+      /* Cancel this because otherwise it would be used if the transforms
+       * require it.  Don't cancel the 'valid' flag because this would prevent
+       * detection of duplicate chunks.
+       */
+      png_ptr->num_trans = 0;
 
-         if (info_ptr->num_trans > (png_uint_16)num)
-         {
-            png_warning(png_ptr, "Truncating incorrect info tRNS chunk length");
-            info_ptr->num_trans = (png_uint_16)num;
-         }
-      }
+      if (info_ptr != NULL)
+         info_ptr->num_trans = 0;
+
+      png_chunk_benign_error(png_ptr, "tRNS must be after");
    }
 #endif
 
+#ifdef PNG_READ_hIST_SUPPORTED
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0)
+      png_chunk_benign_error(png_ptr, "hIST must be after");
+#endif
+
+#ifdef PNG_READ_bKGD_SUPPORTED
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0)
+      png_chunk_benign_error(png_ptr, "bKGD must be after");
+#endif
 }
 
 void /* PRIVATE */
-png_handle_IEND(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_IEND(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    png_debug(1, "in png_handle_IEND");
 
-   if (!(png_ptr->mode & PNG_HAVE_IHDR) || !(png_ptr->mode & PNG_HAVE_IDAT))
-   {
-      png_error(png_ptr, "No image in file");
-   }
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0 ||
+       (png_ptr->mode & PNG_HAVE_IDAT) == 0)
+      png_chunk_error(png_ptr, "out of place");
 
    png_ptr->mode |= (PNG_AFTER_IDAT | PNG_HAVE_IEND);
 
-   if (length != 0)
-   {
-      png_warning(png_ptr, "Incorrect IEND chunk length");
-   }
-
    png_crc_finish(png_ptr, length);
 
-   PNG_UNUSED(info_ptr) /* Quiet compiler warnings about unused info_ptr */
+   if (length != 0)
+      png_chunk_benign_error(png_ptr, "invalid");
+
+   PNG_UNUSED(info_ptr)
 }
 
 #ifdef PNG_READ_gAMA_SUPPORTED
 void /* PRIVATE */
-png_handle_gAMA(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_gAMA(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    png_fixed_point igamma;
    png_byte buf[4];
 
    png_debug(1, "in png_handle_gAMA");
 
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before gAMA");
-
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
-   {
-      png_warning(png_ptr, "Invalid gAMA after IDAT");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   else if (png_ptr->mode & PNG_HAVE_PLTE)
-      /* Should be an error, but we can cope with it */
-      png_warning(png_ptr, "Out of place gAMA chunk");
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
+      png_chunk_error(png_ptr, "missing IHDR");
 
-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_gAMA)
-#ifdef PNG_READ_sRGB_SUPPORTED
-       && !(info_ptr->valid & PNG_INFO_sRGB)
-#endif
-       )
+   else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
    {
-      png_warning(png_ptr, "Duplicate gAMA chunk");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
 
    if (length != 4)
    {
-      png_warning(png_ptr, "Incorrect gAMA chunk length");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 
    png_crc_read(png_ptr, buf, 4);
 
-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
       return;
 
    igamma = png_get_fixed_point(NULL, buf);
 
-   /* Check for zero gamma or an error. */
-   if (igamma <= 0)
-   {
-      png_warning(png_ptr,
-          "Ignoring gAMA chunk with out of range gamma");
-
-      return;
-   }
-
-#  ifdef PNG_READ_sRGB_SUPPORTED
-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sRGB))
-   {
-      if (PNG_OUT_OF_RANGE(igamma, 45500, 500))
-      {
-         PNG_WARNING_PARAMETERS(p)
-         png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_fixed, igamma);
-         png_formatted_warning(png_ptr, p,
-             "Ignoring incorrect gAMA value @1 when sRGB is also present");
-         return;
-      }
-   }
-#  endif /* PNG_READ_sRGB_SUPPORTED */
-
-#  ifdef PNG_READ_GAMMA_SUPPORTED
-   /* Gamma correction on read is supported. */
-   png_ptr->gamma = igamma;
-#  endif
-   /* And set the 'info' structure members. */
-   png_set_gAMA_fixed(png_ptr, info_ptr, igamma);
+   png_colorspace_set_gamma(png_ptr, &png_ptr->colorspace, igamma);
+   png_colorspace_sync(png_ptr, info_ptr);
 }
 #endif
 
 #ifdef PNG_READ_sBIT_SUPPORTED
 void /* PRIVATE */
-png_handle_sBIT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
-   png_size_t truelen;
+   unsigned int truelen, i;
+   png_byte sample_depth;
    png_byte buf[4];
 
    png_debug(1, "in png_handle_sBIT");
 
-   buf[0] = buf[1] = buf[2] = buf[3] = 0;
-
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before sBIT");
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
+      png_chunk_error(png_ptr, "missing IHDR");
 
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
    {
-      png_warning(png_ptr, "Invalid sBIT after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
 
-   else if (png_ptr->mode & PNG_HAVE_PLTE)
-   {
-      /* Should be an error, but we can cope with it */
-      png_warning(png_ptr, "Out of place sBIT chunk");
-   }
-
-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT))
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT) != 0)
    {
-      png_warning(png_ptr, "Duplicate sBIT chunk");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
 
    if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+   {
       truelen = 3;
+      sample_depth = 8;
+   }
 
    else
-      truelen = (png_size_t)png_ptr->channels;
+   {
+      truelen = png_ptr->channels;
+      sample_depth = png_ptr->bit_depth;
+   }
 
    if (length != truelen || length > 4)
    {
-      png_warning(png_ptr, "Incorrect sBIT chunk length");
+      png_chunk_benign_error(png_ptr, "invalid");
       png_crc_finish(png_ptr, length);
       return;
    }
 
+   buf[0] = buf[1] = buf[2] = buf[3] = sample_depth;
    png_crc_read(png_ptr, buf, truelen);
 
-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
       return;
 
-   if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
+   for (i=0; i<truelen; ++i)
+      if (buf[i] == 0 || buf[i] > sample_depth)
+      {
+         png_chunk_benign_error(png_ptr, "invalid");
+         return;
+      }
+
+   if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
    {
       png_ptr->sig_bit.red = buf[0];
       png_ptr->sig_bit.green = buf[1];
@@ -917,474 +1176,418 @@ png_handle_sBIT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
 #ifdef PNG_READ_cHRM_SUPPORTED
 void /* PRIVATE */
-png_handle_cHRM(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_cHRM(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    png_byte buf[32];
-   png_fixed_point x_white, y_white, x_red, y_red, x_green, y_green, x_blue,
-      y_blue;
+   png_xy xy;
 
    png_debug(1, "in png_handle_cHRM");
 
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before cHRM");
-
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
-   {
-      png_warning(png_ptr, "Invalid cHRM after IDAT");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   else if (png_ptr->mode & PNG_HAVE_PLTE)
-      /* Should be an error, but we can cope with it */
-      png_warning(png_ptr, "Out of place cHRM chunk");
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
+      png_chunk_error(png_ptr, "missing IHDR");
 
-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM)
-#  ifdef PNG_READ_sRGB_SUPPORTED
-       && !(info_ptr->valid & PNG_INFO_sRGB)
-#  endif
-      )
+   else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
    {
-      png_warning(png_ptr, "Duplicate cHRM chunk");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
 
    if (length != 32)
    {
-      png_warning(png_ptr, "Incorrect cHRM chunk length");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 
    png_crc_read(png_ptr, buf, 32);
 
-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
       return;
 
-   x_white = png_get_fixed_point(NULL, buf);
-   y_white = png_get_fixed_point(NULL, buf + 4);
-   x_red   = png_get_fixed_point(NULL, buf + 8);
-   y_red   = png_get_fixed_point(NULL, buf + 12);
-   x_green = png_get_fixed_point(NULL, buf + 16);
-   y_green = png_get_fixed_point(NULL, buf + 20);
-   x_blue  = png_get_fixed_point(NULL, buf + 24);
-   y_blue  = png_get_fixed_point(NULL, buf + 28);
-
-   if (x_white == PNG_FIXED_ERROR ||
-       y_white == PNG_FIXED_ERROR ||
-       x_red   == PNG_FIXED_ERROR ||
-       y_red   == PNG_FIXED_ERROR ||
-       x_green == PNG_FIXED_ERROR ||
-       y_green == PNG_FIXED_ERROR ||
-       x_blue  == PNG_FIXED_ERROR ||
-       y_blue  == PNG_FIXED_ERROR)
-   {
-      png_warning(png_ptr, "Ignoring cHRM chunk with negative chromaticities");
+   xy.whitex = png_get_fixed_point(NULL, buf);
+   xy.whitey = png_get_fixed_point(NULL, buf + 4);
+   xy.redx   = png_get_fixed_point(NULL, buf + 8);
+   xy.redy   = png_get_fixed_point(NULL, buf + 12);
+   xy.greenx = png_get_fixed_point(NULL, buf + 16);
+   xy.greeny = png_get_fixed_point(NULL, buf + 20);
+   xy.bluex  = png_get_fixed_point(NULL, buf + 24);
+   xy.bluey  = png_get_fixed_point(NULL, buf + 28);
+
+   if (xy.whitex == PNG_FIXED_ERROR ||
+       xy.whitey == PNG_FIXED_ERROR ||
+       xy.redx   == PNG_FIXED_ERROR ||
+       xy.redy   == PNG_FIXED_ERROR ||
+       xy.greenx == PNG_FIXED_ERROR ||
+       xy.greeny == PNG_FIXED_ERROR ||
+       xy.bluex  == PNG_FIXED_ERROR ||
+       xy.bluey  == PNG_FIXED_ERROR)
+   {
+      png_chunk_benign_error(png_ptr, "invalid values");
       return;
    }
 
-#ifdef PNG_READ_sRGB_SUPPORTED
-   if ((info_ptr != NULL) && (info_ptr->valid & PNG_INFO_sRGB))
-   {
-      if (PNG_OUT_OF_RANGE(x_white, 31270,  1000) ||
-          PNG_OUT_OF_RANGE(y_white, 32900,  1000) ||
-          PNG_OUT_OF_RANGE(x_red,   64000,  1000) ||
-          PNG_OUT_OF_RANGE(y_red,   33000,  1000) ||
-          PNG_OUT_OF_RANGE(x_green, 30000,  1000) ||
-          PNG_OUT_OF_RANGE(y_green, 60000,  1000) ||
-          PNG_OUT_OF_RANGE(x_blue,  15000,  1000) ||
-          PNG_OUT_OF_RANGE(y_blue,   6000,  1000))
-      {
-         PNG_WARNING_PARAMETERS(p)
-
-         png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_fixed, x_white);
-         png_warning_parameter_signed(p, 2, PNG_NUMBER_FORMAT_fixed, y_white);
-         png_warning_parameter_signed(p, 3, PNG_NUMBER_FORMAT_fixed, x_red);
-         png_warning_parameter_signed(p, 4, PNG_NUMBER_FORMAT_fixed, y_red);
-         png_warning_parameter_signed(p, 5, PNG_NUMBER_FORMAT_fixed, x_green);
-         png_warning_parameter_signed(p, 6, PNG_NUMBER_FORMAT_fixed, y_green);
-         png_warning_parameter_signed(p, 7, PNG_NUMBER_FORMAT_fixed, x_blue);
-         png_warning_parameter_signed(p, 8, PNG_NUMBER_FORMAT_fixed, y_blue);
-
-         png_formatted_warning(png_ptr, p,
-             "Ignoring incorrect cHRM white(@1,@2) r(@3,@4)g(@5,@6)b(@7,@8) "
-             "when sRGB is also present");
-      }
+   /* If a colorspace error has already been output skip this chunk */
+   if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
       return;
-   }
-#endif /* PNG_READ_sRGB_SUPPORTED */
 
-#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
-   /* Store the _white values as default coefficients for the rgb to gray
-    * operation if it is supported.  Check if the transform is already set to
-    * avoid destroying the transform values.
-    */
-   if (!png_ptr->rgb_to_gray_coefficients_set)
+   if ((png_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM) != 0)
    {
-      /* png_set_background has not been called and we haven't seen an sRGB
-       * chunk yet.  Find the XYZ of the three end points.
-       */
-      png_XYZ XYZ;
-      png_xy xy;
-
-      xy.redx = x_red;
-      xy.redy = y_red;
-      xy.greenx = x_green;
-      xy.greeny = y_green;
-      xy.bluex = x_blue;
-      xy.bluey = y_blue;
-      xy.whitex = x_white;
-      xy.whitey = y_white;
-
-      if (png_XYZ_from_xy_checked(png_ptr, &XYZ, xy))
-      {
-         /* The success case, because XYZ_from_xy normalises to a reference
-          * white Y of 1.0 we just need to scale the numbers.  This should
-          * always work just fine. It is an internal error if this overflows.
-          */
-         {
-            png_fixed_point r, g, b;
-            if (png_muldiv(&r, XYZ.redY, 32768, PNG_FP_1) &&
-               r >= 0 && r <= 32768 &&
-               png_muldiv(&g, XYZ.greenY, 32768, PNG_FP_1) &&
-               g >= 0 && g <= 32768 &&
-               png_muldiv(&b, XYZ.blueY, 32768, PNG_FP_1) &&
-               b >= 0 && b <= 32768 &&
-               r+g+b <= 32769)
-            {
-               /* We allow 0 coefficients here.  r+g+b may be 32769 if two or
-                * all of the coefficients were rounded up.  Handle this by
-                * reducing the *largest* coefficient by 1; this matches the
-                * approach used for the default coefficients in pngrtran.c
-                */
-               int add = 0;
-
-               if (r+g+b > 32768)
-                  add = -1;
-               else if (r+g+b < 32768)
-                  add = 1;
-
-               if (add != 0)
-               {
-                  if (g >= r && g >= b)
-                     g += add;
-                  else if (r >= g && r >= b)
-                     r += add;
-                  else
-                     b += add;
-               }
-
-               /* Check for an internal error. */
-               if (r+g+b != 32768)
-                  png_error(png_ptr,
-                     "internal error handling cHRM coefficients");
-
-               png_ptr->rgb_to_gray_red_coeff   = (png_uint_16)r;
-               png_ptr->rgb_to_gray_green_coeff = (png_uint_16)g;
-            }
-
-            /* This is a png_error at present even though it could be ignored -
-             * it should never happen, but it is important that if it does, the
-             * bug is fixed.
-             */
-            else
-               png_error(png_ptr, "internal error handling cHRM->XYZ");
-         }
-      }
+      png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
+      png_colorspace_sync(png_ptr, info_ptr);
+      png_chunk_benign_error(png_ptr, "duplicate");
+      return;
    }
-#endif
 
-   png_set_cHRM_fixed(png_ptr, info_ptr, x_white, y_white, x_red, y_red,
-      x_green, y_green, x_blue, y_blue);
+   png_ptr->colorspace.flags |= PNG_COLORSPACE_FROM_cHRM;
+   (void)png_colorspace_set_chromaticities(png_ptr, &png_ptr->colorspace, &xy,
+      1/*prefer cHRM values*/);
+   png_colorspace_sync(png_ptr, info_ptr);
 }
 #endif
 
 #ifdef PNG_READ_sRGB_SUPPORTED
 void /* PRIVATE */
-png_handle_sRGB(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_sRGB(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
-   int intent;
-   png_byte buf[1];
+   png_byte intent;
 
    png_debug(1, "in png_handle_sRGB");
 
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before sRGB");
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
+      png_chunk_error(png_ptr, "missing IHDR");
 
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
    {
-      png_warning(png_ptr, "Invalid sRGB after IDAT");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   else if (png_ptr->mode & PNG_HAVE_PLTE)
-      /* Should be an error, but we can cope with it */
-      png_warning(png_ptr, "Out of place sRGB chunk");
-
-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sRGB))
-   {
-      png_warning(png_ptr, "Duplicate sRGB chunk");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
 
    if (length != 1)
    {
-      png_warning(png_ptr, "Incorrect sRGB chunk length");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 
-   png_crc_read(png_ptr, buf, 1);
+   png_crc_read(png_ptr, &intent, 1);
 
-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
       return;
 
-   intent = buf[0];
-
-   /* Check for bad intent */
-   if (intent >= PNG_sRGB_INTENT_LAST)
-   {
-      png_warning(png_ptr, "Unknown sRGB intent");
+   /* If a colorspace error has already been output skip this chunk */
+   if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
       return;
-   }
 
-#if defined(PNG_READ_gAMA_SUPPORTED) && defined(PNG_READ_GAMMA_SUPPORTED)
-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_gAMA))
+   /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
+    * this.
+    */
+   if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) != 0)
    {
-      if (PNG_OUT_OF_RANGE(info_ptr->gamma, 45500, 500))
-      {
-         PNG_WARNING_PARAMETERS(p)
-
-         png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_fixed,
-            info_ptr->gamma);
-
-         png_formatted_warning(png_ptr, p,
-             "Ignoring incorrect gAMA value @1 when sRGB is also present");
-      }
+      png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
+      png_colorspace_sync(png_ptr, info_ptr);
+      png_chunk_benign_error(png_ptr, "too many profiles");
+      return;
    }
-#endif /* PNG_READ_gAMA_SUPPORTED */
-
-#ifdef PNG_READ_cHRM_SUPPORTED
-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM))
-      if (PNG_OUT_OF_RANGE(info_ptr->x_white, 31270,  1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->y_white, 32900,  1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->x_red,   64000,  1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->y_red,   33000,  1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->x_green, 30000,  1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->y_green, 60000,  1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->x_blue,  15000,  1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->y_blue,   6000,  1000))
-      {
-         png_warning(png_ptr,
-             "Ignoring incorrect cHRM value when sRGB is also present");
-      }
-#endif /* PNG_READ_cHRM_SUPPORTED */
-
-   /* This is recorded for use when handling the cHRM chunk above.  An sRGB
-    * chunk unconditionally overwrites the coefficients for grayscale conversion
-    * too.
-    */
-   png_ptr->is_sRGB = 1;
-
-#  ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
-      /* Don't overwrite user supplied values: */
-      if (!png_ptr->rgb_to_gray_coefficients_set)
-      {
-         /* These numbers come from the sRGB specification (or, since one has to
-          * pay much money to get a copy, the wikipedia sRGB page) the
-          * chromaticity values quoted have been inverted to get the reverse
-          * transformation from RGB to XYZ and the 'Y' coefficients scaled by
-          * 32768 (then rounded).
-          *
-          * sRGB and ITU Rec-709 both truncate the values for the D65 white
-          * point to four digits and, even though it actually stores five
-          * digits, the PNG spec gives the truncated value.
-          *
-          * This means that when the chromaticities are converted back to XYZ
-          * end points we end up with (6968,23435,2366), which, as described in
-          * pngrtran.c, would overflow.  If the five digit precision and up is
-          * used we get, instead:
-          *
-          *    6968*R + 23435*G + 2365*B
-          *
-          * (Notice that this rounds the blue coefficient down, rather than the
-          * choice used in pngrtran.c which is to round the green one down.)
-          */
-         png_ptr->rgb_to_gray_red_coeff   =  6968; /* 0.212639005871510 */
-         png_ptr->rgb_to_gray_green_coeff = 23434; /* 0.715168678767756 */
-         /* png_ptr->rgb_to_gray_blue_coeff  =  2366; 0.072192315360734	*/
-
-         /* The following keeps the cHRM chunk from destroying the
-          * coefficients again in the event that it follows the sRGB chunk.
-          */
-         png_ptr->rgb_to_gray_coefficients_set = 1;
-      }
-#  endif
 
-   png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr, intent);
+   (void)png_colorspace_set_sRGB(png_ptr, &png_ptr->colorspace, intent);
+   png_colorspace_sync(png_ptr, info_ptr);
 }
-#endif /* PNG_READ_sRGB_SUPPORTED */
+#endif /* READ_sRGB */
 
 #ifdef PNG_READ_iCCP_SUPPORTED
 void /* PRIVATE */
-png_handle_iCCP(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
-/* Note: this does not properly handle chunks that are > 64K under DOS */
+png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+/* Note: this does not properly handle profiles that are > 64K under DOS */
 {
-   png_byte compression_type;
-   png_bytep pC;
-   png_charp profile;
-   png_uint_32 skip = 0;
-   png_uint_32 profile_size;
-   png_alloc_size_t profile_length;
-   png_size_t slength, prefix_length, data_length;
+   png_const_charp errmsg = NULL; /* error message output, or no error */
+   int finished = 0; /* crc checked */
 
    png_debug(1, "in png_handle_iCCP");
 
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before iCCP");
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
+      png_chunk_error(png_ptr, "missing IHDR");
 
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
    {
-      png_warning(png_ptr, "Invalid iCCP after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
 
-   else if (png_ptr->mode & PNG_HAVE_PLTE)
-      /* Should be an error, but we can cope with it */
-      png_warning(png_ptr, "Out of place iCCP chunk");
-
-   if ((png_ptr->mode & PNG_HAVE_iCCP) || (info_ptr != NULL &&
-      (info_ptr->valid & (PNG_INFO_iCCP|PNG_INFO_sRGB))))
+   /* Consistent with all the above colorspace handling an obviously *invalid*
+    * chunk is just ignored, so does not invalidate the color space.  An
+    * alternative is to set the 'invalid' flags at the start of this routine
+    * and only clear them in they were not set before and all the tests pass.
+    * The minimum 'deflate' stream is assumed to be just the 2 byte header and
+    * 4 byte checksum.  The keyword must be at least one character and there is
+    * a terminator (0) byte and the compression method.
+    */
+   if (length < 9)
    {
-      png_warning(png_ptr, "Duplicate iCCP chunk");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "too short");
       return;
    }
 
-   png_ptr->mode |= PNG_HAVE_iCCP;
-
-#ifdef PNG_MAX_MALLOC_64K
-   if (length > (png_uint_32)65535L)
+   /* If a colorspace error has already been output skip this chunk */
+   if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
    {
-      png_warning(png_ptr, "iCCP chunk too large to fit in memory");
-      skip = length - (png_uint_32)65535L;
-      length = (png_uint_32)65535L;
+      png_crc_finish(png_ptr, length);
+      return;
    }
-#endif
 
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = (png_charp)png_malloc(png_ptr, length + 1);
-   slength = length;
-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
-
-   if (png_crc_finish(png_ptr, skip))
+   /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
+    * this.
+    */
+   if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) == 0)
    {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
+      uInt read_length, keyword_length;
+      char keyword[81];
 
-   png_ptr->chunkdata[slength] = 0x00;
+      /* Find the keyword; the keyword plus separator and compression method
+       * bytes can be at most 81 characters long.
+       */
+      read_length = 81; /* maximum */
+      if (read_length > length)
+         read_length = (uInt)length;
 
-   for (profile = png_ptr->chunkdata; *profile; profile++)
-      /* Empty loop to find end of name */ ;
+      png_crc_read(png_ptr, (png_bytep)keyword, read_length);
+      length -= read_length;
 
-   ++profile;
+      keyword_length = 0;
+      while (keyword_length < 80 && keyword_length < read_length &&
+         keyword[keyword_length] != 0)
+         ++keyword_length;
 
-   /* There should be at least one zero (the compression type byte)
-    * following the separator, and we should be on it
-    */
-   if (profile >= png_ptr->chunkdata + slength - 1)
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      png_warning(png_ptr, "Malformed iCCP chunk");
-      return;
-   }
+      /* TODO: make the keyword checking common */
+      if (keyword_length >= 1 && keyword_length <= 79)
+      {
+         /* We only understand '0' compression - deflate - so if we get a
+          * different value we can't safely decode the chunk.
+          */
+         if (keyword_length+1 < read_length &&
+            keyword[keyword_length+1] == PNG_COMPRESSION_TYPE_BASE)
+         {
+            read_length -= keyword_length+2;
 
-   /* Compression_type should always be zero */
-   compression_type = *profile++;
+            if (png_inflate_claim(png_ptr, png_iCCP) == Z_OK)
+            {
+               Byte profile_header[132];
+               Byte local_buffer[PNG_INFLATE_BUF_SIZE];
+               png_alloc_size_t size = (sizeof profile_header);
 
-   if (compression_type)
-   {
-      png_warning(png_ptr, "Ignoring nonzero compression type in iCCP chunk");
-      compression_type = 0x00;  /* Reset it to zero (libpng-1.0.6 through 1.0.8
-                                 wrote nonzero) */
-   }
+               png_ptr->zstream.next_in = (Bytef*)keyword + (keyword_length+2);
+               png_ptr->zstream.avail_in = read_length;
+               (void)png_inflate_read(png_ptr, local_buffer,
+                  (sizeof local_buffer), &length, profile_header, &size,
+                  0/*finish: don't, because the output is too small*/);
 
-   prefix_length = profile - png_ptr->chunkdata;
-   png_decompress_chunk(png_ptr, compression_type,
-       slength, prefix_length, &data_length);
+               if (size == 0)
+               {
+                  /* We have the ICC profile header; do the basic header checks.
+                   */
+                  const png_uint_32 profile_length =
+                     png_get_uint_32(profile_header);
 
-   profile_length = data_length - prefix_length;
+                  if (png_icc_check_length(png_ptr, &png_ptr->colorspace,
+                     keyword, profile_length) != 0)
+                  {
+                     /* The length is apparently ok, so we can check the 132
+                      * byte header.
+                      */
+                     if (png_icc_check_header(png_ptr, &png_ptr->colorspace,
+                        keyword, profile_length, profile_header,
+                        png_ptr->color_type) != 0)
+                     {
+                        /* Now read the tag table; a variable size buffer is
+                         * needed at this point, allocate one for the whole
+                         * profile.  The header check has already validated
+                         * that none of these stuff will overflow.
+                         */
+                        const png_uint_32 tag_count = png_get_uint_32(
+                           profile_header+128);
+                        png_bytep profile = png_read_buffer(png_ptr,
+                           profile_length, 2/*silent*/);
+
+                        if (profile != NULL)
+                        {
+                           memcpy(profile, profile_header,
+                              (sizeof profile_header));
+
+                           size = 12 * tag_count;
+
+                           (void)png_inflate_read(png_ptr, local_buffer,
+                              (sizeof local_buffer), &length,
+                              profile + (sizeof profile_header), &size, 0);
+
+                           /* Still expect a buffer error because we expect
+                            * there to be some tag data!
+                            */
+                           if (size == 0)
+                           {
+                              if (png_icc_check_tag_table(png_ptr,
+                                 &png_ptr->colorspace, keyword, profile_length,
+                                 profile) != 0)
+                              {
+                                 /* The profile has been validated for basic
+                                  * security issues, so read the whole thing in.
+                                  */
+                                 size = profile_length - (sizeof profile_header)
+                                    - 12 * tag_count;
+
+                                 (void)png_inflate_read(png_ptr, local_buffer,
+                                    (sizeof local_buffer), &length,
+                                    profile + (sizeof profile_header) +
+                                    12 * tag_count, &size, 1/*finish*/);
+
+                                 if (length > 0 && !(png_ptr->flags &
+                                       PNG_FLAG_BENIGN_ERRORS_WARN))
+                                    errmsg = "extra compressed data";
+
+                                 /* But otherwise allow extra data: */
+                                 else if (size == 0)
+                                 {
+                                    if (length > 0)
+                                    {
+                                       /* This can be handled completely, so
+                                        * keep going.
+                                        */
+                                       png_chunk_warning(png_ptr,
+                                          "extra compressed data");
+                                    }
+
+                                    png_crc_finish(png_ptr, length);
+                                    finished = 1;
+
+#                                   ifdef PNG_sRGB_SUPPORTED
+                                       /* Check for a match against sRGB */
+                                       png_icc_set_sRGB(png_ptr,
+                                          &png_ptr->colorspace, profile,
+                                          png_ptr->zstream.adler);
+#                                   endif
+
+                                    /* Steal the profile for info_ptr. */
+                                    if (info_ptr != NULL)
+                                    {
+                                       png_free_data(png_ptr, info_ptr,
+                                          PNG_FREE_ICCP, 0);
+
+                                       info_ptr->iccp_name = png_voidcast(char*,
+                                          png_malloc_base(png_ptr,
+                                          keyword_length+1));
+                                       if (info_ptr->iccp_name != NULL)
+                                       {
+                                          memcpy(info_ptr->iccp_name, keyword,
+                                             keyword_length+1);
+                                          info_ptr->iccp_proflen =
+                                             profile_length;
+                                          info_ptr->iccp_profile = profile;
+                                          png_ptr->read_buffer = NULL; /*steal*/
+                                          info_ptr->free_me |= PNG_FREE_ICCP;
+                                          info_ptr->valid |= PNG_INFO_iCCP;
+                                       }
+
+                                       else
+                                       {
+                                          png_ptr->colorspace.flags |=
+                                             PNG_COLORSPACE_INVALID;
+                                          errmsg = "out of memory";
+                                       }
+                                    }
+
+                                    /* else the profile remains in the read
+                                     * buffer which gets reused for subsequent
+                                     * chunks.
+                                     */
+
+                                    if (info_ptr != NULL)
+                                       png_colorspace_sync(png_ptr, info_ptr);
+
+                                    if (errmsg == NULL)
+                                    {
+                                       png_ptr->zowner = 0;
+                                       return;
+                                    }
+                                 }
+
+                                 else if (size > 0)
+                                    errmsg = "truncated";
+
+#ifndef __COVERITY__
+                                 else
+                                    errmsg = png_ptr->zstream.msg;
+#endif
+                              }
 
-   if (prefix_length > data_length || profile_length < 4)
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      png_warning(png_ptr, "Profile size field missing from iCCP chunk");
-      return;
-   }
+                              /* else png_icc_check_tag_table output an error */
+                           }
 
-   /* Check the profile_size recorded in the first 32 bits of the ICC profile */
-   pC = (png_bytep)(png_ptr->chunkdata + prefix_length);
-   profile_size = ((*(pC    )) << 24) |
-                  ((*(pC + 1)) << 16) |
-                  ((*(pC + 2)) <<  8) |
-                  ((*(pC + 3))      );
+                           else /* profile truncated */
+                              errmsg = png_ptr->zstream.msg;
+                        }
 
-   /* NOTE: the following guarantees that 'profile_length' fits into 32 bits,
-    * because profile_size is a 32 bit value.
-    */
-   if (profile_size < profile_length)
-      profile_length = profile_size;
+                        else
+                           errmsg = "out of memory";
+                     }
 
-   /* And the following guarantees that profile_size == profile_length. */
-   if (profile_size > profile_length)
-   {
-      PNG_WARNING_PARAMETERS(p)
+                     /* else png_icc_check_header output an error */
+                  }
 
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
+                  /* else png_icc_check_length output an error */
+               }
 
-      png_warning_parameter_unsigned(p, 1, PNG_NUMBER_FORMAT_u, profile_size);
-      png_warning_parameter_unsigned(p, 2, PNG_NUMBER_FORMAT_u, profile_length);
-      png_formatted_warning(png_ptr, p,
-         "Ignoring iCCP chunk with declared size = @1 and actual length = @2");
-      return;
+               else /* profile truncated */
+                  errmsg = png_ptr->zstream.msg;
+
+               /* Release the stream */
+               png_ptr->zowner = 0;
+            }
+
+            else /* png_inflate_claim failed */
+               errmsg = png_ptr->zstream.msg;
+         }
+
+         else
+            errmsg = "bad compression method"; /* or missing */
+      }
+
+      else
+         errmsg = "bad keyword";
    }
 
-   png_set_iCCP(png_ptr, info_ptr, png_ptr->chunkdata,
-       compression_type, (png_bytep)png_ptr->chunkdata + prefix_length,
-       profile_size);
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = NULL;
+   else
+      errmsg = "too many profiles";
+
+   /* Failure: the reason is in 'errmsg' */
+   if (finished == 0)
+      png_crc_finish(png_ptr, length);
+
+   png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
+   png_colorspace_sync(png_ptr, info_ptr);
+   if (errmsg != NULL) /* else already output */
+      png_chunk_benign_error(png_ptr, errmsg);
 }
-#endif /* PNG_READ_iCCP_SUPPORTED */
+#endif /* READ_iCCP */
 
 #ifdef PNG_READ_sPLT_SUPPORTED
 void /* PRIVATE */
-png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 /* Note: this does not properly handle chunks that are > 64K under DOS */
 {
-   png_bytep entry_start;
+   png_bytep entry_start, buffer;
    png_sPLT_t new_palette;
    png_sPLT_entryp pp;
    png_uint_32 data_length;
    int entry_size, i;
    png_uint_32 skip = 0;
-   png_size_t slength;
    png_uint_32 dl;
    png_size_t max_dl;
 
    png_debug(1, "in png_handle_sPLT");
 
 #ifdef PNG_USER_LIMITS_SUPPORTED
-
    if (png_ptr->user_chunk_cache_max != 0)
    {
       if (png_ptr->user_chunk_cache_max == 1)
@@ -1402,55 +1605,53 @@ png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 #endif
 
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before sPLT");
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
+      png_chunk_error(png_ptr, "missing IHDR");
 
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
    {
-      png_warning(png_ptr, "Invalid sPLT after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
 
 #ifdef PNG_MAX_MALLOC_64K
-   if (length > (png_uint_32)65535L)
+   if (length > 65535U)
    {
-      png_warning(png_ptr, "sPLT chunk too large to fit in memory");
-      skip = length - (png_uint_32)65535L;
-      length = (png_uint_32)65535L;
+      png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "too large to fit in memory");
+      return;
    }
 #endif
 
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = (png_charp)png_malloc(png_ptr, length + 1);
+   buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
+   if (buffer == NULL)
+   {
+      png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of memory");
+      return;
+   }
+
 
    /* WARNING: this may break if size_t is less than 32 bits; it is assumed
     * that the PNG_MAX_MALLOC_64K test is enabled in this case, but this is a
     * potential breakage point if the types in pngconf.h aren't exactly right.
     */
-   slength = length;
-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+   png_crc_read(png_ptr, buffer, length);
 
-   if (png_crc_finish(png_ptr, skip))
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
+   if (png_crc_finish(png_ptr, skip) != 0)
       return;
-   }
 
-   png_ptr->chunkdata[slength] = 0x00;
+   buffer[length] = 0;
 
-   for (entry_start = (png_bytep)png_ptr->chunkdata; *entry_start;
-       entry_start++)
+   for (entry_start = buffer; *entry_start; entry_start++)
       /* Empty loop to find end of name */ ;
 
    ++entry_start;
 
    /* A sample depth should follow the separator, and we should be on it  */
-   if (entry_start > (png_bytep)png_ptr->chunkdata + slength - 2)
+   if (entry_start > buffer + length - 2)
    {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
       png_warning(png_ptr, "malformed sPLT chunk");
       return;
    }
@@ -1458,23 +1659,19 @@ png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    new_palette.depth = *entry_start++;
    entry_size = (new_palette.depth == 8 ? 6 : 10);
    /* This must fit in a png_uint_32 because it is derived from the original
-    * chunk data length (and use 'length', not 'slength' here for clarity -
-    * they are guaranteed to be the same, see the tests above.)
+    * chunk data length.
     */
-   data_length = length - (png_uint_32)(entry_start -
-      (png_bytep)png_ptr->chunkdata);
+   data_length = length - (png_uint_32)(entry_start - buffer);
 
    /* Integrity-check the data length */
-   if (data_length % entry_size)
+   if ((data_length % entry_size) != 0)
    {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
       png_warning(png_ptr, "sPLT chunk has bad length");
       return;
    }
 
    dl = (png_int_32)(data_length / entry_size);
-   max_dl = PNG_SIZE_MAX / png_sizeof(png_sPLT_entry);
+   max_dl = PNG_SIZE_MAX / (sizeof (png_sPLT_entry));
 
    if (dl > max_dl)
    {
@@ -1485,7 +1682,7 @@ png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    new_palette.nentries = (png_int_32)(data_length / entry_size);
 
    new_palette.entries = (png_sPLT_entryp)png_malloc_warn(
-       png_ptr, new_palette.nentries * png_sizeof(png_sPLT_entry));
+       png_ptr, new_palette.nentries * (sizeof (png_sPLT_entry)));
 
    if (new_palette.entries == NULL)
    {
@@ -1543,38 +1740,36 @@ png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 #endif
 
    /* Discard all chunk data except the name and stash that */
-   new_palette.name = png_ptr->chunkdata;
+   new_palette.name = (png_charp)buffer;
 
    png_set_sPLT(png_ptr, info_ptr, &new_palette, 1);
 
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = NULL;
    png_free(png_ptr, new_palette.entries);
 }
-#endif /* PNG_READ_sPLT_SUPPORTED */
+#endif /* READ_sPLT */
 
 #ifdef PNG_READ_tRNS_SUPPORTED
 void /* PRIVATE */
-png_handle_tRNS(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    png_byte readbuf[PNG_MAX_PALETTE_LENGTH];
 
    png_debug(1, "in png_handle_tRNS");
 
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before tRNS");
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
+      png_chunk_error(png_ptr, "missing IHDR");
 
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
    {
-      png_warning(png_ptr, "Invalid tRNS after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
 
-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0)
    {
-      png_warning(png_ptr, "Duplicate tRNS chunk");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
 
@@ -1584,8 +1779,8 @@ png_handle_tRNS(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
       if (length != 2)
       {
-         png_warning(png_ptr, "Incorrect tRNS chunk length");
          png_crc_finish(png_ptr, length);
+         png_chunk_benign_error(png_ptr, "invalid");
          return;
       }
 
@@ -1600,12 +1795,12 @@ png_handle_tRNS(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
       if (length != 6)
       {
-         png_warning(png_ptr, "Incorrect tRNS chunk length");
          png_crc_finish(png_ptr, length);
+         png_chunk_benign_error(png_ptr, "invalid");
          return;
       }
 
-      png_crc_read(png_ptr, buf, (png_size_t)length);
+      png_crc_read(png_ptr, buf, length);
       png_ptr->num_trans = 1;
       png_ptr->trans_color.red = png_get_uint_16(buf);
       png_ptr->trans_color.green = png_get_uint_16(buf + 2);
@@ -1614,44 +1809,43 @@ png_handle_tRNS(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
    {
-      if (!(png_ptr->mode & PNG_HAVE_PLTE))
-      {
-         /* Should be an error, but we can cope with it. */
-         png_warning(png_ptr, "Missing PLTE before tRNS");
-      }
-
-      if (length > (png_uint_32)png_ptr->num_palette ||
-          length > PNG_MAX_PALETTE_LENGTH)
+      if ((png_ptr->mode & PNG_HAVE_PLTE) == 0)
       {
-         png_warning(png_ptr, "Incorrect tRNS chunk length");
+         /* TODO: is this actually an error in the ISO spec? */
          png_crc_finish(png_ptr, length);
+         png_chunk_benign_error(png_ptr, "out of place");
          return;
       }
 
-      if (length == 0)
+      if (length > png_ptr->num_palette || length > PNG_MAX_PALETTE_LENGTH ||
+         length == 0)
       {
-         png_warning(png_ptr, "Zero length tRNS chunk");
          png_crc_finish(png_ptr, length);
+         png_chunk_benign_error(png_ptr, "invalid");
          return;
       }
 
-      png_crc_read(png_ptr, readbuf, (png_size_t)length);
+      png_crc_read(png_ptr, readbuf, length);
       png_ptr->num_trans = (png_uint_16)length;
    }
 
    else
    {
-      png_warning(png_ptr, "tRNS chunk not allowed with alpha channel");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "invalid with alpha channel");
       return;
    }
 
-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
    {
       png_ptr->num_trans = 0;
       return;
    }
 
+   /* TODO: this is a horrible side effect in the palette case because the
+    * png_struct ends up with a pointer to the tRNS buffer owned by the
+    * png_info.  Fix this.
+    */
    png_set_tRNS(png_ptr, info_ptr, readbuf, png_ptr->num_trans,
        &(png_ptr->trans_color));
 }
@@ -1659,43 +1853,37 @@ png_handle_tRNS(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
 #ifdef PNG_READ_bKGD_SUPPORTED
 void /* PRIVATE */
-png_handle_bKGD(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
-   png_size_t truelen;
+   unsigned int truelen;
    png_byte buf[6];
    png_color_16 background;
 
    png_debug(1, "in png_handle_bKGD");
 
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before bKGD");
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
+      png_chunk_error(png_ptr, "missing IHDR");
 
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0 ||
+       (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
+       (png_ptr->mode & PNG_HAVE_PLTE) == 0))
    {
-      png_warning(png_ptr, "Invalid bKGD after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
 
-   else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
-       !(png_ptr->mode & PNG_HAVE_PLTE))
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0)
    {
-      png_warning(png_ptr, "Missing PLTE before bKGD");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD))
-   {
-      png_warning(png_ptr, "Duplicate bKGD chunk");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
 
    if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
       truelen = 1;
 
-   else if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
+   else if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
       truelen = 6;
 
    else
@@ -1703,14 +1891,14 @@ png_handle_bKGD(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    if (length != truelen)
    {
-      png_warning(png_ptr, "Incorrect bKGD chunk length");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 
    png_crc_read(png_ptr, buf, truelen);
 
-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
       return;
 
    /* We convert the index value into RGB components so that we can allow
@@ -1722,11 +1910,11 @@ png_handle_bKGD(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    {
       background.index = buf[0];
 
-      if (info_ptr && info_ptr->num_palette)
+      if (info_ptr != NULL && info_ptr->num_palette != 0)
       {
          if (buf[0] >= info_ptr->num_palette)
          {
-            png_warning(png_ptr, "Incorrect bKGD chunk index value");
+            png_chunk_benign_error(png_ptr, "invalid index");
             return;
          }
 
@@ -1741,7 +1929,7 @@ png_handle_bKGD(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       background.gray = 0;
    }
 
-   else if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR)) /* GRAY */
+   else if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0) /* GRAY */
    {
       background.index = 0;
       background.red =
@@ -1765,47 +1953,40 @@ png_handle_bKGD(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
 #ifdef PNG_READ_hIST_SUPPORTED
 void /* PRIVATE */
-png_handle_hIST(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    unsigned int num, i;
    png_uint_16 readbuf[PNG_MAX_PALETTE_LENGTH];
 
    png_debug(1, "in png_handle_hIST");
 
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before hIST");
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
+      png_chunk_error(png_ptr, "missing IHDR");
 
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0 ||
+       (png_ptr->mode & PNG_HAVE_PLTE) == 0)
    {
-      png_warning(png_ptr, "Invalid hIST after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
 
-   else if (!(png_ptr->mode & PNG_HAVE_PLTE))
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0)
    {
-      png_warning(png_ptr, "Missing PLTE before hIST");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
 
-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST))
-   {
-      png_warning(png_ptr, "Duplicate hIST chunk");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
+   num = length / 2 ;
 
-   if (length > 2*PNG_MAX_PALETTE_LENGTH ||
-       length != (unsigned int) (2*png_ptr->num_palette))
+   if (num != png_ptr->num_palette || num > PNG_MAX_PALETTE_LENGTH)
    {
-      png_warning(png_ptr, "Incorrect hIST chunk length");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 
-   num = length / 2 ;
-
    for (i = 0; i < num; i++)
    {
       png_byte buf[2];
@@ -1814,7 +1995,7 @@ png_handle_hIST(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       readbuf[i] = png_get_uint_16(buf);
    }
 
-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
       return;
 
    png_set_hIST(png_ptr, info_ptr, readbuf);
@@ -1823,7 +2004,7 @@ png_handle_hIST(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
 #ifdef PNG_READ_pHYs_SUPPORTED
 void /* PRIVATE */
-png_handle_pHYs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_pHYs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    png_byte buf[9];
    png_uint_32 res_x, res_y;
@@ -1831,33 +2012,33 @@ png_handle_pHYs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    png_debug(1, "in png_handle_pHYs");
 
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before pHYs");
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
+      png_chunk_error(png_ptr, "missing IHDR");
 
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
    {
-      png_warning(png_ptr, "Invalid pHYs after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
 
-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs) != 0)
    {
-      png_warning(png_ptr, "Duplicate pHYs chunk");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
 
    if (length != 9)
    {
-      png_warning(png_ptr, "Incorrect pHYs chunk length");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 
    png_crc_read(png_ptr, buf, 9);
 
-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
       return;
 
    res_x = png_get_uint_32(buf);
@@ -1869,7 +2050,7 @@ png_handle_pHYs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
 #ifdef PNG_READ_oFFs_SUPPORTED
 void /* PRIVATE */
-png_handle_oFFs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_oFFs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    png_byte buf[9];
    png_int_32 offset_x, offset_y;
@@ -1877,33 +2058,33 @@ png_handle_oFFs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    png_debug(1, "in png_handle_oFFs");
 
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before oFFs");
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
+      png_chunk_error(png_ptr, "missing IHDR");
 
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
    {
-      png_warning(png_ptr, "Invalid oFFs after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
 
-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs) != 0)
    {
-      png_warning(png_ptr, "Duplicate oFFs chunk");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
 
    if (length != 9)
    {
-      png_warning(png_ptr, "Incorrect oFFs chunk length");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 
    png_crc_read(png_ptr, buf, 9);
 
-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
       return;
 
    offset_x = png_get_int_32(buf);
@@ -1916,71 +2097,64 @@ png_handle_oFFs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 #ifdef PNG_READ_pCAL_SUPPORTED
 /* Read the pCAL chunk (described in the PNG Extensions document) */
 void /* PRIVATE */
-png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    png_int_32 X0, X1;
    png_byte type, nparams;
-   png_charp buf, units, endptr;
+   png_bytep buffer, buf, units, endptr;
    png_charpp params;
-   png_size_t slength;
    int i;
 
    png_debug(1, "in png_handle_pCAL");
 
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before pCAL");
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
+      png_chunk_error(png_ptr, "missing IHDR");
 
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
    {
-      png_warning(png_ptr, "Invalid pCAL after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
 
-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL))
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL) != 0)
    {
-      png_warning(png_ptr, "Duplicate pCAL chunk");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
 
    png_debug1(2, "Allocating and reading pCAL chunk data (%u bytes)",
        length + 1);
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
 
-   if (png_ptr->chunkdata == NULL)
+   buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
+
+   if (buffer == NULL)
    {
-      png_warning(png_ptr, "No memory for pCAL purpose");
+      png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of memory");
       return;
    }
 
-   slength = length;
-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+   png_crc_read(png_ptr, buffer, length);
 
-   if (png_crc_finish(png_ptr, 0))
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
+   if (png_crc_finish(png_ptr, 0) != 0)
       return;
-   }
 
-   png_ptr->chunkdata[slength] = 0x00; /* Null terminate the last string */
+   buffer[length] = 0; /* Null terminate the last string */
 
    png_debug(3, "Finding end of pCAL purpose string");
-   for (buf = png_ptr->chunkdata; *buf; buf++)
+   for (buf = buffer; *buf; buf++)
       /* Empty loop */ ;
 
-   endptr = png_ptr->chunkdata + slength;
+   endptr = buffer + length;
 
    /* We need to have at least 12 bytes after the purpose string
     * in order to get the parameter information.
     */
    if (endptr <= buf + 12)
    {
-      png_warning(png_ptr, "Invalid pCAL data");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
+      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 
@@ -2000,15 +2174,13 @@ png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
        (type == PNG_EQUATION_ARBITRARY && nparams != 3) ||
        (type == PNG_EQUATION_HYPERBOLIC && nparams != 4))
    {
-      png_warning(png_ptr, "Invalid pCAL parameters for equation type");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
+      png_chunk_benign_error(png_ptr, "invalid parameter count");
       return;
    }
 
    else if (type >= PNG_EQUATION_LAST)
    {
-      png_warning(png_ptr, "Unrecognized equation type for pCAL chunk");
+      png_chunk_benign_error(png_ptr, "unrecognized equation type");
    }
 
    for (buf = units; *buf; buf++)
@@ -2016,43 +2188,37 @@ png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    png_debug(3, "Allocating pCAL parameters array");
 
-   params = (png_charpp)png_malloc_warn(png_ptr,
-       (png_size_t)(nparams * png_sizeof(png_charp)));
+   params = png_voidcast(png_charpp, png_malloc_warn(png_ptr,
+       nparams * (sizeof (png_charp))));
 
    if (params == NULL)
    {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      png_warning(png_ptr, "No memory for pCAL params");
+      png_chunk_benign_error(png_ptr, "out of memory");
       return;
    }
 
    /* Get pointers to the start of each parameter string. */
-   for (i = 0; i < (int)nparams; i++)
+   for (i = 0; i < nparams; i++)
    {
       buf++; /* Skip the null string terminator from previous parameter. */
 
       png_debug1(3, "Reading pCAL parameter %d", i);
 
-      for (params[i] = buf; buf <= endptr && *buf != 0x00; buf++)
+      for (params[i] = (png_charp)buf; buf <= endptr && *buf != 0; buf++)
          /* Empty loop to move past each parameter string */ ;
 
       /* Make sure we haven't run out of data yet */
       if (buf > endptr)
       {
-         png_warning(png_ptr, "Invalid pCAL data");
-         png_free(png_ptr, png_ptr->chunkdata);
-         png_ptr->chunkdata = NULL;
          png_free(png_ptr, params);
+         png_chunk_benign_error(png_ptr, "invalid data");
          return;
       }
    }
 
-   png_set_pCAL(png_ptr, info_ptr, png_ptr->chunkdata, X0, X1, type, nparams,
-      units, params);
+   png_set_pCAL(png_ptr, info_ptr, (png_charp)buffer, X0, X1, type, nparams,
+      (png_charp)units, params);
 
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = NULL;
    png_free(png_ptr, params);
 }
 #endif
@@ -2060,67 +2226,61 @@ png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 #ifdef PNG_READ_sCAL_SUPPORTED
 /* Read the sCAL chunk */
 void /* PRIVATE */
-png_handle_sCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
-   png_size_t slength, i;
+   png_bytep buffer;
+   png_size_t i;
    int state;
 
    png_debug(1, "in png_handle_sCAL");
 
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before sCAL");
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
+      png_chunk_error(png_ptr, "missing IHDR");
 
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
    {
-      png_warning(png_ptr, "Invalid sCAL after IDAT");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
 
-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sCAL))
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sCAL) != 0)
    {
-      png_warning(png_ptr, "Duplicate sCAL chunk");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
 
    /* Need unit type, width, \0, height: minimum 4 bytes */
    else if (length < 4)
    {
-      png_warning(png_ptr, "sCAL chunk too short");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 
    png_debug1(2, "Allocating and reading sCAL chunk data (%u bytes)",
       length + 1);
 
-   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+   buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
 
-   if (png_ptr->chunkdata == NULL)
+   if (buffer == NULL)
    {
-      png_warning(png_ptr, "Out of memory while processing sCAL chunk");
+      png_chunk_benign_error(png_ptr, "out of memory");
       png_crc_finish(png_ptr, length);
       return;
    }
 
-   slength = length;
-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
-   png_ptr->chunkdata[slength] = 0x00; /* Null terminate the last string */
+   png_crc_read(png_ptr, buffer, length);
+   buffer[length] = 0; /* Null terminate the last string */
 
-   if (png_crc_finish(png_ptr, 0))
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
+   if (png_crc_finish(png_ptr, 0) != 0)
       return;
-   }
 
    /* Validate the unit. */
-   if (png_ptr->chunkdata[0] != 1 && png_ptr->chunkdata[0] != 2)
+   if (buffer[0] != 1 && buffer[0] != 2)
    {
-      png_warning(png_ptr, "Invalid sCAL ignored: invalid unit");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
+      png_chunk_benign_error(png_ptr, "invalid unit");
       return;
    }
 
@@ -2130,70 +2290,65 @@ png_handle_sCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    i = 1;
    state = 0;
 
-   if (!png_check_fp_number(png_ptr->chunkdata, slength, &state, &i) ||
-       i >= slength || png_ptr->chunkdata[i++] != 0)
-      png_warning(png_ptr, "Invalid sCAL chunk ignored: bad width format");
+   if (png_check_fp_number((png_const_charp)buffer, length, &state, &i) == 0 ||
+       i >= length || buffer[i++] != 0)
+      png_chunk_benign_error(png_ptr, "bad width format");
 
-   else if (!PNG_FP_IS_POSITIVE(state))
-      png_warning(png_ptr, "Invalid sCAL chunk ignored: non-positive width");
+   else if (PNG_FP_IS_POSITIVE(state) == 0)
+      png_chunk_benign_error(png_ptr, "non-positive width");
 
    else
    {
       png_size_t heighti = i;
 
       state = 0;
-      if (!png_check_fp_number(png_ptr->chunkdata, slength, &state, &i) ||
-          i != slength)
-         png_warning(png_ptr, "Invalid sCAL chunk ignored: bad height format");
+      if (png_check_fp_number((png_const_charp)buffer, length,
+          &state, &i) == 0 || i != length)
+         png_chunk_benign_error(png_ptr, "bad height format");
 
-      else if (!PNG_FP_IS_POSITIVE(state))
-         png_warning(png_ptr,
-            "Invalid sCAL chunk ignored: non-positive height");
+      else if (PNG_FP_IS_POSITIVE(state) == 0)
+         png_chunk_benign_error(png_ptr, "non-positive height");
 
       else
          /* This is the (only) success case. */
-         png_set_sCAL_s(png_ptr, info_ptr, png_ptr->chunkdata[0],
-            png_ptr->chunkdata+1, png_ptr->chunkdata+heighti);
+         png_set_sCAL_s(png_ptr, info_ptr, buffer[0],
+            (png_charp)buffer+1, (png_charp)buffer+heighti);
    }
-
-   /* Clean up - just free the temporarily allocated buffer. */
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = NULL;
 }
 #endif
 
 #ifdef PNG_READ_tIME_SUPPORTED
 void /* PRIVATE */
-png_handle_tIME(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_tIME(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    png_byte buf[7];
    png_time mod_time;
 
    png_debug(1, "in png_handle_tIME");
 
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Out of place tIME chunk");
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
+      png_chunk_error(png_ptr, "missing IHDR");
 
-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME))
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME) != 0)
    {
-      png_warning(png_ptr, "Duplicate tIME chunk");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
 
-   if (png_ptr->mode & PNG_HAVE_IDAT)
+   if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
       png_ptr->mode |= PNG_AFTER_IDAT;
 
    if (length != 7)
    {
-      png_warning(png_ptr, "Incorrect tIME chunk length");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 
    png_crc_read(png_ptr, buf, 7);
 
-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
       return;
 
    mod_time.second = buf[6];
@@ -2210,14 +2365,13 @@ png_handle_tIME(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 #ifdef PNG_READ_tEXt_SUPPORTED
 /* Note: this does not properly handle chunks that are > 64K under DOS */
 void /* PRIVATE */
-png_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_tEXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
-   png_textp text_ptr;
+   png_text  text_info;
+   png_bytep buffer;
    png_charp key;
    png_charp text;
    png_uint_32 skip = 0;
-   png_size_t slength;
-   int ret;
 
    png_debug(1, "in png_handle_tEXt");
 
@@ -2232,84 +2386,59 @@ png_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
       if (--png_ptr->user_chunk_cache_max == 1)
       {
-         png_warning(png_ptr, "No space in chunk cache for tEXt");
          png_crc_finish(png_ptr, length);
+         png_chunk_benign_error(png_ptr, "no space in chunk cache");
          return;
       }
    }
 #endif
 
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before tEXt");
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
+      png_chunk_error(png_ptr, "missing IHDR");
 
-   if (png_ptr->mode & PNG_HAVE_IDAT)
+   if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
       png_ptr->mode |= PNG_AFTER_IDAT;
 
 #ifdef PNG_MAX_MALLOC_64K
-   if (length > (png_uint_32)65535L)
+   if (length > 65535U)
    {
-      png_warning(png_ptr, "tEXt chunk too large to fit in memory");
-      skip = length - (png_uint_32)65535L;
-      length = (png_uint_32)65535L;
+      png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "too large to fit in memory");
+      return;
    }
 #endif
 
-   png_free(png_ptr, png_ptr->chunkdata);
-
-   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+   buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
 
-   if (png_ptr->chunkdata == NULL)
+   if (buffer == NULL)
    {
-     png_warning(png_ptr, "No memory to process text chunk");
+     png_chunk_benign_error(png_ptr, "out of memory");
      return;
    }
 
-   slength = length;
-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+   png_crc_read(png_ptr, buffer, length);
 
-   if (png_crc_finish(png_ptr, skip))
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
+   if (png_crc_finish(png_ptr, skip) != 0)
       return;
-   }
-
-   key = png_ptr->chunkdata;
 
-   key[slength] = 0x00;
+   key = (png_charp)buffer;
+   key[length] = 0;
 
    for (text = key; *text; text++)
       /* Empty loop to find end of key */ ;
 
-   if (text != key + slength)
+   if (text != key + length)
       text++;
 
-   text_ptr = (png_textp)png_malloc_warn(png_ptr,
-       png_sizeof(png_text));
-
-   if (text_ptr == NULL)
-   {
-      png_warning(png_ptr, "Not enough memory to process text chunk");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
-
-   text_ptr->compression = PNG_TEXT_COMPRESSION_NONE;
-   text_ptr->key = key;
-   text_ptr->lang = NULL;
-   text_ptr->lang_key = NULL;
-   text_ptr->itxt_length = 0;
-   text_ptr->text = text;
-   text_ptr->text_length = png_strlen(text);
-
-   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
-
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = NULL;
-   png_free(png_ptr, text_ptr);
+   text_info.compression = PNG_TEXT_COMPRESSION_NONE;
+   text_info.key = key;
+   text_info.lang = NULL;
+   text_info.lang_key = NULL;
+   text_info.itxt_length = 0;
+   text_info.text = text;
+   text_info.text_length = strlen(text);
 
-   if (ret)
+   if (png_set_text_2(png_ptr, info_ptr, &text_info, 1) != 0)
       png_warning(png_ptr, "Insufficient memory to process text chunk");
 }
 #endif
@@ -2317,13 +2446,11 @@ png_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 #ifdef PNG_READ_zTXt_SUPPORTED
 /* Note: this does not correctly handle chunks that are > 64K under DOS */
 void /* PRIVATE */
-png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
-   png_textp text_ptr;
-   png_charp text;
-   int comp_type;
-   int ret;
-   png_size_t slength, prefix_len, data_len;
+   png_const_charp errmsg = NULL;
+   png_bytep       buffer;
+   png_uint_32     keyword_length;
 
    png_debug(1, "in png_handle_zTXt");
 
@@ -2338,123 +2465,101 @@ png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
       if (--png_ptr->user_chunk_cache_max == 1)
       {
-         png_warning(png_ptr, "No space in chunk cache for zTXt");
          png_crc_finish(png_ptr, length);
+         png_chunk_benign_error(png_ptr, "no space in chunk cache");
          return;
       }
    }
 #endif
 
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before zTXt");
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
+      png_chunk_error(png_ptr, "missing IHDR");
 
-   if (png_ptr->mode & PNG_HAVE_IDAT)
+   if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
       png_ptr->mode |= PNG_AFTER_IDAT;
 
-#ifdef PNG_MAX_MALLOC_64K
-   /* We will no doubt have problems with chunks even half this size, but
-    * there is no hard and fast rule to tell us where to stop.
-    */
-   if (length > (png_uint_32)65535L)
+   buffer = png_read_buffer(png_ptr, length, 2/*silent*/);
+
+   if (buffer == NULL)
    {
-      png_warning(png_ptr, "zTXt chunk too large to fit in memory");
       png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of memory");
       return;
    }
-#endif
 
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+   png_crc_read(png_ptr, buffer, length);
 
-   if (png_ptr->chunkdata == NULL)
-   {
-      png_warning(png_ptr, "Out of memory processing zTXt chunk");
+   if (png_crc_finish(png_ptr, 0) != 0)
       return;
-   }
-
-   slength = length;
-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
 
-   if (png_crc_finish(png_ptr, 0))
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
+   /* TODO: also check that the keyword contents match the spec! */
+   for (keyword_length = 0;
+      keyword_length < length && buffer[keyword_length] != 0;
+      ++keyword_length)
+      /* Empty loop to find end of name */ ;
 
-   png_ptr->chunkdata[slength] = 0x00;
+   if (keyword_length > 79 || keyword_length < 1)
+      errmsg = "bad keyword";
 
-   for (text = png_ptr->chunkdata; *text; text++)
-      /* Empty loop */ ;
+   /* zTXt must have some LZ data after the keyword, although it may expand to
+    * zero bytes; we need a '\0' at the end of the keyword, the compression type
+    * then the LZ data:
+    */
+   else if (keyword_length + 3 > length)
+      errmsg = "truncated";
 
-   /* zTXt must have some text after the chunkdataword */
-   if (text >= png_ptr->chunkdata + slength - 2)
-   {
-      png_warning(png_ptr, "Truncated zTXt chunk");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
+   else if (buffer[keyword_length+1] != PNG_COMPRESSION_TYPE_BASE)
+      errmsg = "unknown compression type";
 
    else
    {
-       comp_type = *(++text);
-
-       if (comp_type != PNG_TEXT_COMPRESSION_zTXt)
-       {
-          png_warning(png_ptr, "Unknown compression type in zTXt chunk");
-          comp_type = PNG_TEXT_COMPRESSION_zTXt;
-       }
+      png_alloc_size_t uncompressed_length = PNG_SIZE_MAX;
 
-       text++;        /* Skip the compression_method byte */
-   }
-
-   prefix_len = text - png_ptr->chunkdata;
-
-   png_decompress_chunk(png_ptr, comp_type,
-       (png_size_t)length, prefix_len, &data_len);
+      /* TODO: at present png_decompress_chunk imposes a single application
+       * level memory limit, this should be split to different values for iCCP
+       * and text chunks.
+       */
+      if (png_decompress_chunk(png_ptr, length, keyword_length+2,
+         &uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
+      {
+         png_text text;
 
-   text_ptr = (png_textp)png_malloc_warn(png_ptr,
-       png_sizeof(png_text));
+         /* It worked; png_ptr->read_buffer now looks like a tEXt chunk except
+          * for the extra compression type byte and the fact that it isn't
+          * necessarily '\0' terminated.
+          */
+         buffer = png_ptr->read_buffer;
+         buffer[uncompressed_length+(keyword_length+2)] = 0;
+
+         text.compression = PNG_TEXT_COMPRESSION_zTXt;
+         text.key = (png_charp)buffer;
+         text.text = (png_charp)(buffer + keyword_length+2);
+         text.text_length = uncompressed_length;
+         text.itxt_length = 0;
+         text.lang = NULL;
+         text.lang_key = NULL;
+
+         if (png_set_text_2(png_ptr, info_ptr, &text, 1) != 0)
+            errmsg = "insufficient memory";
+      }
 
-   if (text_ptr == NULL)
-   {
-      png_warning(png_ptr, "Not enough memory to process zTXt chunk");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
+      else
+         errmsg = png_ptr->zstream.msg;
    }
 
-   text_ptr->compression = comp_type;
-   text_ptr->key = png_ptr->chunkdata;
-   text_ptr->lang = NULL;
-   text_ptr->lang_key = NULL;
-   text_ptr->itxt_length = 0;
-   text_ptr->text = png_ptr->chunkdata + prefix_len;
-   text_ptr->text_length = data_len;
-
-   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
-
-   png_free(png_ptr, text_ptr);
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = NULL;
-
-   if (ret)
-      png_error(png_ptr, "Insufficient memory to store zTXt chunk");
+   if (errmsg != NULL)
+      png_chunk_benign_error(png_ptr, errmsg);
 }
 #endif
 
 #ifdef PNG_READ_iTXt_SUPPORTED
 /* Note: this does not correctly handle chunks that are > 64K under DOS */
 void /* PRIVATE */
-png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
-   png_textp text_ptr;
-   png_charp key, lang, text, lang_key;
-   int comp_flag;
-   int comp_type = 0;
-   int ret;
-   png_size_t slength, prefix_len, data_len;
+   png_const_charp errmsg = NULL;
+   png_bytep buffer;
+   png_uint_32 prefix_length;
 
    png_debug(1, "in png_handle_iTXt");
 
@@ -2469,279 +2574,393 @@ png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
       if (--png_ptr->user_chunk_cache_max == 1)
       {
-         png_warning(png_ptr, "No space in chunk cache for iTXt");
          png_crc_finish(png_ptr, length);
+         png_chunk_benign_error(png_ptr, "no space in chunk cache");
          return;
       }
    }
 #endif
 
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before iTXt");
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
+      png_chunk_error(png_ptr, "missing IHDR");
 
-   if (png_ptr->mode & PNG_HAVE_IDAT)
+   if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
       png_ptr->mode |= PNG_AFTER_IDAT;
 
-#ifdef PNG_MAX_MALLOC_64K
-   /* We will no doubt have problems with chunks even half this size, but
-    * there is no hard and fast rule to tell us where to stop.
-    */
-   if (length > (png_uint_32)65535L)
-   {
-      png_warning(png_ptr, "iTXt chunk too large to fit in memory");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-#endif
-
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+   buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
 
-   if (png_ptr->chunkdata == NULL)
+   if (buffer == NULL)
    {
-      png_warning(png_ptr, "No memory to process iTXt chunk");
+      png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of memory");
       return;
    }
 
-   slength = length;
-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+   png_crc_read(png_ptr, buffer, length);
 
-   if (png_crc_finish(png_ptr, 0))
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
+   if (png_crc_finish(png_ptr, 0) != 0)
       return;
-   }
 
-   png_ptr->chunkdata[slength] = 0x00;
-
-   for (lang = png_ptr->chunkdata; *lang; lang++)
+   /* First the keyword. */
+   for (prefix_length=0;
+      prefix_length < length && buffer[prefix_length] != 0;
+      ++prefix_length)
       /* Empty loop */ ;
 
-   lang++;        /* Skip NUL separator */
+   /* Perform a basic check on the keyword length here. */
+   if (prefix_length > 79 || prefix_length < 1)
+      errmsg = "bad keyword";
 
-   /* iTXt must have a language tag (possibly empty), two compression bytes,
-    * translated keyword (possibly empty), and possibly some text after the
-    * keyword
+   /* Expect keyword, compression flag, compression type, language, translated
+    * keyword (both may be empty but are 0 terminated) then the text, which may
+    * be empty.
     */
+   else if (prefix_length + 5 > length)
+      errmsg = "truncated";
 
-   if (lang >= png_ptr->chunkdata + slength - 3)
+   else if (buffer[prefix_length+1] == 0 ||
+      (buffer[prefix_length+1] == 1 &&
+      buffer[prefix_length+2] == PNG_COMPRESSION_TYPE_BASE))
    {
-      png_warning(png_ptr, "Truncated iTXt chunk");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
+      int compressed = buffer[prefix_length+1] != 0;
+      png_uint_32 language_offset, translated_keyword_offset;
+      png_alloc_size_t uncompressed_length = 0;
 
-   else
-   {
-      comp_flag = *lang++;
-      comp_type = *lang++;
-   }
+      /* Now the language tag */
+      prefix_length += 3;
+      language_offset = prefix_length;
 
-   if (comp_type || (comp_flag && comp_flag != PNG_TEXT_COMPRESSION_zTXt))
-   {
-      png_warning(png_ptr, "Unknown iTXt compression type or method");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
+      for (; prefix_length < length && buffer[prefix_length] != 0;
+         ++prefix_length)
+         /* Empty loop */ ;
 
-   for (lang_key = lang; *lang_key; lang_key++)
-      /* Empty loop */ ;
+      /* WARNING: the length may be invalid here, this is checked below. */
+      translated_keyword_offset = ++prefix_length;
 
-   lang_key++;        /* Skip NUL separator */
+      for (; prefix_length < length && buffer[prefix_length] != 0;
+         ++prefix_length)
+         /* Empty loop */ ;
 
-   if (lang_key >= png_ptr->chunkdata + slength)
-   {
-      png_warning(png_ptr, "Truncated iTXt chunk");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
+      /* prefix_length should now be at the trailing '\0' of the translated
+       * keyword, but it may already be over the end.  None of this arithmetic
+       * can overflow because chunks are at most 2^31 bytes long, but on 16-bit
+       * systems the available allocation may overflow.
+       */
+      ++prefix_length;
 
-   for (text = lang_key; *text; text++)
-      /* Empty loop */ ;
+      if (compressed == 0 && prefix_length <= length)
+         uncompressed_length = length - prefix_length;
 
-   text++;        /* Skip NUL separator */
+      else if (compressed != 0 && prefix_length < length)
+      {
+         uncompressed_length = PNG_SIZE_MAX;
 
-   if (text >= png_ptr->chunkdata + slength)
-   {
-      png_warning(png_ptr, "Malformed iTXt chunk");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
+         /* TODO: at present png_decompress_chunk imposes a single application
+          * level memory limit, this should be split to different values for
+          * iCCP and text chunks.
+          */
+         if (png_decompress_chunk(png_ptr, length, prefix_length,
+            &uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
+            buffer = png_ptr->read_buffer;
 
-   prefix_len = text - png_ptr->chunkdata;
+         else
+            errmsg = png_ptr->zstream.msg;
+      }
 
-   key=png_ptr->chunkdata;
+      else
+         errmsg = "truncated";
 
-   if (comp_flag)
-      png_decompress_chunk(png_ptr, comp_type,
-          (size_t)length, prefix_len, &data_len);
+      if (errmsg == NULL)
+      {
+         png_text text;
 
-   else
-      data_len = png_strlen(png_ptr->chunkdata + prefix_len);
+         buffer[uncompressed_length+prefix_length] = 0;
 
-   text_ptr = (png_textp)png_malloc_warn(png_ptr,
-       png_sizeof(png_text));
+         if (compressed == 0)
+            text.compression = PNG_ITXT_COMPRESSION_NONE;
 
-   if (text_ptr == NULL)
-   {
-      png_warning(png_ptr, "Not enough memory to process iTXt chunk");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
+         else
+            text.compression = PNG_ITXT_COMPRESSION_zTXt;
 
-   text_ptr->compression = (int)comp_flag + 1;
-   text_ptr->lang_key = png_ptr->chunkdata + (lang_key - key);
-   text_ptr->lang = png_ptr->chunkdata + (lang - key);
-   text_ptr->itxt_length = data_len;
-   text_ptr->text_length = 0;
-   text_ptr->key = png_ptr->chunkdata;
-   text_ptr->text = png_ptr->chunkdata + prefix_len;
+         text.key = (png_charp)buffer;
+         text.lang = (png_charp)buffer + language_offset;
+         text.lang_key = (png_charp)buffer + translated_keyword_offset;
+         text.text = (png_charp)buffer + prefix_length;
+         text.text_length = 0;
+         text.itxt_length = uncompressed_length;
 
-   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
+         if (png_set_text_2(png_ptr, info_ptr, &text, 1) != 0)
+            errmsg = "insufficient memory";
+      }
+   }
 
-   png_free(png_ptr, text_ptr);
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = NULL;
+   else
+      errmsg = "bad compression info";
 
-   if (ret)
-      png_error(png_ptr, "Insufficient memory to store iTXt chunk");
+   if (errmsg != NULL)
+      png_chunk_benign_error(png_ptr, errmsg);
 }
 #endif
 
-/* This function is called when we haven't found a handler for a
- * chunk.  If there isn't a problem with the chunk itself (ie bad
- * chunk name, CRC, or a critical chunk), the chunk is silently ignored
- * -- unless the PNG_FLAG_UNKNOWN_CHUNKS_SUPPORTED flag is on in which
- * case it will be saved away to be written out later.
- */
-void /* PRIVATE */
-png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
+/* Utility function for png_handle_unknown; set up png_ptr::unknown_chunk */
+static int
+png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length)
 {
-   png_uint_32 skip = 0;
+   png_alloc_size_t limit = PNG_SIZE_MAX;
 
-   png_debug(1, "in png_handle_unknown");
+   if (png_ptr->unknown_chunk.data != NULL)
+   {
+      png_free(png_ptr, png_ptr->unknown_chunk.data);
+      png_ptr->unknown_chunk.data = NULL;
+   }
 
-#ifdef PNG_USER_LIMITS_SUPPORTED
-   if (png_ptr->user_chunk_cache_max != 0)
+#  ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
+      if (png_ptr->user_chunk_malloc_max > 0 &&
+          png_ptr->user_chunk_malloc_max < limit)
+         limit = png_ptr->user_chunk_malloc_max;
+
+#  elif PNG_USER_CHUNK_MALLOC_MAX > 0
+      if (PNG_USER_CHUNK_MALLOC_MAX < limit)
+         limit = PNG_USER_CHUNK_MALLOC_MAX;
+#  endif
+
+   if (length <= limit)
    {
-      if (png_ptr->user_chunk_cache_max == 1)
-      {
-         png_crc_finish(png_ptr, length);
-         return;
-      }
+      PNG_CSTRING_FROM_CHUNK(png_ptr->unknown_chunk.name, png_ptr->chunk_name);
+      /* The following is safe because of the PNG_SIZE_MAX init above */
+      png_ptr->unknown_chunk.size = (png_size_t)length/*SAFE*/;
+      /* 'mode' is a flag array, only the bottom four bits matter here */
+      png_ptr->unknown_chunk.location = (png_byte)png_ptr->mode/*SAFE*/;
 
-      if (--png_ptr->user_chunk_cache_max == 1)
+      if (length == 0)
+         png_ptr->unknown_chunk.data = NULL;
+
+      else
       {
-         png_warning(png_ptr, "No space in chunk cache for unknown chunk");
-         png_crc_finish(png_ptr, length);
-         return;
+         /* Do a 'warn' here - it is handled below. */
+         png_ptr->unknown_chunk.data = png_voidcast(png_bytep,
+            png_malloc_warn(png_ptr, length));
       }
    }
-#endif
 
-   if (png_ptr->mode & PNG_HAVE_IDAT)
+   if (png_ptr->unknown_chunk.data == NULL && length > 0)
    {
-      if (png_ptr->chunk_name != png_IDAT)
-         png_ptr->mode |= PNG_AFTER_IDAT;
+      /* This is benign because we clean up correctly */
+      png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "unknown chunk exceeds memory limits");
+      return 0;
    }
 
-   if (PNG_CHUNK_CRITICAL(png_ptr->chunk_name))
+   else
    {
-#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
-      if (png_chunk_unknown_handling(png_ptr, png_ptr->chunk_name) !=
-          PNG_HANDLE_CHUNK_ALWAYS
-#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
-          && png_ptr->read_user_chunk_fn == NULL
-#endif
-          )
-#endif
-         png_chunk_error(png_ptr, "unknown critical chunk");
+      if (length > 0)
+         png_crc_read(png_ptr, png_ptr->unknown_chunk.data, length);
+      png_crc_finish(png_ptr, 0);
+      return 1;
    }
+}
+#endif /* READ_UNKNOWN_CHUNKS */
+
+/* Handle an unknown, or known but disabled, chunk */
+void /* PRIVATE */
+png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
+   png_uint_32 length, int keep)
+{
+   int handled = 0; /* the chunk was handled */
+
+   png_debug(1, "in png_handle_unknown");
 
 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
-   if ((png_ptr->flags & PNG_FLAG_KEEP_UNKNOWN_CHUNKS)
-#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
-       || (png_ptr->read_user_chunk_fn != NULL)
-#endif
-       )
-   {
-#ifdef PNG_MAX_MALLOC_64K
-      if (length > 65535)
-      {
-         png_warning(png_ptr, "unknown chunk too large to fit in memory");
-         skip = length - 65535;
-         length = 65535;
-      }
-#endif
+   /* NOTE: this code is based on the code in libpng-1.4.12 except for fixing
+    * the bug which meant that setting a non-default behavior for a specific
+    * chunk would be ignored (the default was always used unless a user
+    * callback was installed).
+    *
+    * 'keep' is the value from the png_chunk_unknown_handling, the setting for
+    * this specific chunk_name, if PNG_HANDLE_AS_UNKNOWN_SUPPORTED, if not it
+    * will always be PNG_HANDLE_CHUNK_AS_DEFAULT and it needs to be set here.
+    * This is just an optimization to avoid multiple calls to the lookup
+    * function.
+    */
+#  ifndef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+#     ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
+         keep = png_chunk_unknown_handling(png_ptr, png_ptr->chunk_name);
+#     endif
+#  endif
 
-      /* TODO: this code is very close to the unknown handling in pngpread.c,
-       * maybe it can be put into a common utility routine?
-       * png_struct::unknown_chunk is just used as a temporary variable, along
-       * with the data into which the chunk is read.  These can be eliminated.
+   /* One of the following methods will read the chunk or skip it (at least one
+    * of these is always defined because this is the only way to switch on
+    * PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
+    */
+#  ifdef PNG_READ_USER_CHUNKS_SUPPORTED
+      /* The user callback takes precedence over the chunk keep value, but the
+       * keep value is still required to validate a save of a critical chunk.
        */
-      PNG_CSTRING_FROM_CHUNK(png_ptr->unknown_chunk.name, png_ptr->chunk_name);
-      png_ptr->unknown_chunk.size = (png_size_t)length;
+      if (png_ptr->read_user_chunk_fn != NULL)
+      {
+         if (png_cache_unknown_chunk(png_ptr, length) != 0)
+         {
+            /* Callback to user unknown chunk handler */
+            int ret = (*(png_ptr->read_user_chunk_fn))(png_ptr,
+               &png_ptr->unknown_chunk);
+
+            /* ret is:
+             * negative: An error occurred; png_chunk_error will be called.
+             *     zero: The chunk was not handled, the chunk will be discarded
+             *           unless png_set_keep_unknown_chunks has been used to set
+             *           a 'keep' behavior for this particular chunk, in which
+             *           case that will be used.  A critical chunk will cause an
+             *           error at this point unless it is to be saved.
+             * positive: The chunk was handled, libpng will ignore/discard it.
+             */
+            if (ret < 0)
+               png_chunk_error(png_ptr, "error in user chunk");
 
-      if (length == 0)
-         png_ptr->unknown_chunk.data = NULL;
+            else if (ret == 0)
+            {
+               /* If the keep value is 'default' or 'never' override it, but
+                * still error out on critical chunks unless the keep value is
+                * 'always'  While this is weird it is the behavior in 1.4.12.
+                * A possible improvement would be to obey the value set for the
+                * chunk, but this would be an API change that would probably
+                * damage some applications.
+                *
+                * The png_app_warning below catches the case that matters, where
+                * the application has not set specific save or ignore for this
+                * chunk or global save or ignore.
+                */
+               if (keep < PNG_HANDLE_CHUNK_IF_SAFE)
+               {
+#                 ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
+                     if (png_ptr->unknown_default < PNG_HANDLE_CHUNK_IF_SAFE)
+                     {
+                        png_chunk_warning(png_ptr, "Saving unknown chunk:");
+                        png_app_warning(png_ptr,
+                           "forcing save of an unhandled chunk;"
+                           " please call png_set_keep_unknown_chunks");
+                           /* with keep = PNG_HANDLE_CHUNK_IF_SAFE */
+                     }
+#                 endif
+                  keep = PNG_HANDLE_CHUNK_IF_SAFE;
+               }
+            }
+
+            else /* chunk was handled */
+            {
+               handled = 1;
+               /* Critical chunks can be safely discarded at this point. */
+               keep = PNG_HANDLE_CHUNK_NEVER;
+            }
+         }
+
+         else
+            keep = PNG_HANDLE_CHUNK_NEVER; /* insufficient memory */
+      }
 
       else
+         /* Use the SAVE_UNKNOWN_CHUNKS code or skip the chunk */
+#  endif /* READ_USER_CHUNKS */
+
+#  ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
       {
-         png_ptr->unknown_chunk.data = (png_bytep)png_malloc(png_ptr, length);
-         png_crc_read(png_ptr, png_ptr->unknown_chunk.data, length);
+         /* keep is currently just the per-chunk setting, if there was no
+          * setting change it to the global default now (not that this may
+          * still be AS_DEFAULT) then obtain the cache of the chunk if required,
+          * if not simply skip the chunk.
+          */
+         if (keep == PNG_HANDLE_CHUNK_AS_DEFAULT)
+            keep = png_ptr->unknown_default;
+
+         if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
+            (keep == PNG_HANDLE_CHUNK_IF_SAFE &&
+             PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
+         {
+            if (png_cache_unknown_chunk(png_ptr, length) == 0)
+               keep = PNG_HANDLE_CHUNK_NEVER;
+         }
+
+         else
+            png_crc_finish(png_ptr, length);
       }
+#  else
+#     ifndef PNG_READ_USER_CHUNKS_SUPPORTED
+#        error no method to support READ_UNKNOWN_CHUNKS
+#     endif
 
-#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
-      if (png_ptr->read_user_chunk_fn != NULL)
       {
-         /* Callback to user unknown chunk handler */
-         int ret;
-
-         ret = (*(png_ptr->read_user_chunk_fn))
-             (png_ptr, &png_ptr->unknown_chunk);
+         /* If here there is no read callback pointer set and no support is
+          * compiled in to just save the unknown chunks, so simply skip this
+          * chunk.  If 'keep' is something other than AS_DEFAULT or NEVER then
+          * the app has erroneously asked for unknown chunk saving when there
+          * is no support.
+          */
+         if (keep > PNG_HANDLE_CHUNK_NEVER)
+            png_app_error(png_ptr, "no unknown chunk support available");
 
-         if (ret < 0)
-            png_chunk_error(png_ptr, "error in user chunk");
+         png_crc_finish(png_ptr, length);
+      }
+#  endif
 
-         if (ret == 0)
+#  ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
+      /* Now store the chunk in the chunk list if appropriate, and if the limits
+       * permit it.
+       */
+      if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
+         (keep == PNG_HANDLE_CHUNK_IF_SAFE &&
+          PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
+      {
+#     ifdef PNG_USER_LIMITS_SUPPORTED
+         switch (png_ptr->user_chunk_cache_max)
          {
-            if (PNG_CHUNK_CRITICAL(png_ptr->chunk_name))
-            {
-#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
-               if (png_chunk_unknown_handling(png_ptr, png_ptr->chunk_name) !=
-                   PNG_HANDLE_CHUNK_ALWAYS)
-#endif
-                  png_chunk_error(png_ptr, "unknown critical chunk");
-            }
+            case 2:
+               png_ptr->user_chunk_cache_max = 1;
+               png_chunk_benign_error(png_ptr, "no space in chunk cache");
+               /* FALL THROUGH */
+            case 1:
+               /* NOTE: prior to 1.6.0 this case resulted in an unknown critical
+                * chunk being skipped, now there will be a hard error below.
+                */
+               break;
 
-            png_set_unknown_chunks(png_ptr, info_ptr,
-                &png_ptr->unknown_chunk, 1);
+            default: /* not at limit */
+               --(png_ptr->user_chunk_cache_max);
+               /* FALL THROUGH */
+            case 0: /* no limit */
+#     endif /* USER_LIMITS */
+               /* Here when the limit isn't reached or when limits are compiled
+                * out; store the chunk.
+                */
+               png_set_unknown_chunks(png_ptr, info_ptr,
+                  &png_ptr->unknown_chunk, 1);
+               handled = 1;
+#     ifdef PNG_USER_LIMITS_SUPPORTED
+               break;
          }
+#     endif
       }
+#  else /* no store support: the chunk must be handled by the user callback */
+      PNG_UNUSED(info_ptr)
+#  endif
 
-      else
-#endif
-         png_set_unknown_chunks(png_ptr, info_ptr, &png_ptr->unknown_chunk, 1);
-
+   /* Regardless of the error handling below the cached data (if any) can be
+    * freed now.  Notice that the data is not freed if there is a png_error, but
+    * it will be freed by destroy_read_struct.
+    */
+   if (png_ptr->unknown_chunk.data != NULL)
       png_free(png_ptr, png_ptr->unknown_chunk.data);
-      png_ptr->unknown_chunk.data = NULL;
-   }
-
-   else
-#endif
-      skip = length;
+   png_ptr->unknown_chunk.data = NULL;
 
-   png_crc_finish(png_ptr, skip);
+#else /* !PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
+   /* There is no support to read an unknown chunk, so just skip it. */
+   png_crc_finish(png_ptr, length);
+   PNG_UNUSED(info_ptr)
+   PNG_UNUSED(keep)
+#endif /* !READ_UNKNOWN_CHUNKS */
 
-#ifndef PNG_READ_USER_CHUNKS_SUPPORTED
-   PNG_UNUSED(info_ptr) /* Quiet compiler warnings about unused info_ptr */
-#endif
+   /* Check for unhandled critical chunks */
+   if (handled == 0 && PNG_CHUNK_CRITICAL(png_ptr->chunk_name))
+      png_chunk_error(png_ptr, "unhandled critical chunk");
 }
 
 /* This function is called to verify that a chunk name is valid.
@@ -2757,7 +2976,7 @@ png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
  */
 
 void /* PRIVATE */
-png_check_chunk_name(png_structp png_ptr, png_uint_32 chunk_name)
+png_check_chunk_name(png_structrp png_ptr, png_uint_32 chunk_name)
 {
    int i;
 
@@ -2782,11 +3001,11 @@ png_check_chunk_name(png_structp png_ptr, png_uint_32 chunk_name)
  * 'display' is false only those pixels present in the pass are filled in.
  */
 void /* PRIVATE */
-png_combine_row(png_structp png_ptr, png_bytep dp, int display)
+png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
 {
    unsigned int pixel_depth = png_ptr->transformed_pixel_depth;
    png_const_bytep sp = png_ptr->row_buf + 1;
-   png_uint_32 row_width = png_ptr->width;
+   png_alloc_size_t row_width = png_ptr->width;
    unsigned int pass = png_ptr->pass;
    png_bytep end_ptr = 0;
    png_byte end_byte = 0;
@@ -2823,7 +3042,8 @@ png_combine_row(png_structp png_ptr, png_bytep dp, int display)
       end_ptr = dp + PNG_ROWBYTES(pixel_depth, row_width) - 1;
       end_byte = *end_ptr;
 #     ifdef PNG_READ_PACKSWAP_SUPPORTED
-         if (png_ptr->transformations & PNG_PACKSWAP) /* little-endian byte */
+         if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
+            /* little-endian byte */
             end_mask = 0xff << end_mask;
 
          else /* big-endian byte */
@@ -2832,17 +3052,18 @@ png_combine_row(png_structp png_ptr, png_bytep dp, int display)
       /* end_mask is now the bits to *keep* from the destination row */
    }
 
-   /* For non-interlaced images this reduces to a png_memcpy(). A png_memcpy()
+   /* For non-interlaced images this reduces to a memcpy(). A memcpy()
     * will also happen if interlacing isn't supported or if the application
     * does not call png_set_interlace_handling().  In the latter cases the
     * caller just gets a sequence of the unexpanded rows from each interlace
     * pass.
     */
 #ifdef PNG_READ_INTERLACING_SUPPORTED
-   if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE) &&
-      pass < 6 && (display == 0 ||
-      /* The following copies everything for 'display' on passes 0, 2 and 4. */
-      (display == 1 && (pass & 1) != 0)))
+   if (png_ptr->interlaced != 0 &&
+       (png_ptr->transformations & PNG_INTERLACE) != 0 &&
+       pass < 6 && (display == 0 ||
+       /* The following copies everything for 'display' on passes 0, 2 and 4. */
+       (display == 1 && (pass & 1) != 0)))
    {
       /* Narrow images may have no bits in a pass; the caller should handle
        * this, but this test is cheap:
@@ -2938,7 +3159,7 @@ png_combine_row(png_structp png_ptr, png_bytep dp, int display)
 #        define S_MASKS(d,s) { S_MASK(0,d,s), S_MASK(1,d,s), S_MASK(2,d,s),\
             S_MASK(3,d,s), S_MASK(4,d,s), S_MASK(5,d,s) }
 
-#        define B_MASKS(d,s) { B_MASK(1,d,s), S_MASK(3,d,s), S_MASK(5,d,s) }
+#        define B_MASKS(d,s) { B_MASK(1,d,s), B_MASK(3,d,s), B_MASK(5,d,s) }
 
 #        define DEPTH_INDEX(d) ((d)==1?0:((d)==2?1:2))
 
@@ -2974,10 +3195,10 @@ png_combine_row(png_structp png_ptr, png_bytep dp, int display)
           */
 #        define MASK(pass,depth,display,png)\
             ((display)?B_MASK(pass,depth,png):S_MASK(pass,depth,png))
-#endif /* !PNG_USE_COMPILE_TIME_MASKS */
+#endif /* !USE_COMPILE_TIME_MASKS */
 
          /* Use the appropriate mask to copy the required bits.  In some cases
-          * the byte mask will be 0 or 0xff, optimize these cases.  row_width is
+          * the byte mask will be 0 or 0xff; optimize these cases.  row_width is
           * the number of pixels, but the code copies bytes, so it is necessary
           * to special case the end.
           */
@@ -2985,7 +3206,7 @@ png_combine_row(png_structp png_ptr, png_bytep dp, int display)
          png_uint_32 mask;
 
 #        ifdef PNG_READ_PACKSWAP_SUPPORTED
-            if (png_ptr->transformations & PNG_PACKSWAP)
+            if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
                mask = MASK(pass, pixel_depth, display, 0);
 
             else
@@ -3049,7 +3270,7 @@ png_combine_row(png_structp png_ptr, png_bytep dp, int display)
          }
 
          /* Work out the bytes to copy. */
-         if (display)
+         if (display != 0)
          {
             /* When doing the 'block' algorithm the pixel in the pass gets
              * replicated to adjacent pixels.  This is why the even (0,2,4,6)
@@ -3059,7 +3280,7 @@ png_combine_row(png_structp png_ptr, png_bytep dp, int display)
 
             /* But don't allow this number to exceed the actual row width. */
             if (bytes_to_copy > row_width)
-               bytes_to_copy = row_width;
+               bytes_to_copy = (unsigned int)/*SAFE*/row_width;
          }
 
          else /* normal row; Adam7 only ever gives us one pixel to copy. */
@@ -3116,7 +3337,7 @@ png_combine_row(png_structp png_ptr, png_bytep dp, int display)
                /* This can only be the RGB case, so each copy is exactly one
                 * pixel and it is not necessary to check for a partial copy.
                 */
-               for(;;)
+               for (;;)
                {
                   dp[0] = sp[0], dp[1] = sp[1], dp[2] = sp[2];
 
@@ -3133,26 +3354,27 @@ png_combine_row(png_structp png_ptr, png_bytep dp, int display)
                /* Check for double byte alignment and, if possible, use a
                 * 16-bit copy.  Don't attempt this for narrow images - ones that
                 * are less than an interlace panel wide.  Don't attempt it for
-                * wide bytes_to_copy either - use the png_memcpy there.
+                * wide bytes_to_copy either - use the memcpy there.
                 */
-               if (bytes_to_copy < 16 /*else use png_memcpy*/ &&
-                  png_isaligned(dp, png_uint_16) &&
-                  png_isaligned(sp, png_uint_16) &&
-                  bytes_to_copy % sizeof (png_uint_16) == 0 &&
-                  bytes_to_jump % sizeof (png_uint_16) == 0)
+               if (bytes_to_copy < 16 /*else use memcpy*/ &&
+                   png_isaligned(dp, png_uint_16) &&
+                   png_isaligned(sp, png_uint_16) &&
+                   bytes_to_copy % (sizeof (png_uint_16)) == 0 &&
+                   bytes_to_jump % (sizeof (png_uint_16)) == 0)
                {
                   /* Everything is aligned for png_uint_16 copies, but try for
                    * png_uint_32 first.
                    */
-                  if (png_isaligned(dp, png_uint_32) &&
-                     png_isaligned(sp, png_uint_32) &&
-                     bytes_to_copy % sizeof (png_uint_32) == 0 &&
-                     bytes_to_jump % sizeof (png_uint_32) == 0)
+                  if (png_isaligned(dp, png_uint_32) != 0 &&
+                      png_isaligned(sp, png_uint_32) != 0 &&
+                      bytes_to_copy % (sizeof (png_uint_32)) == 0 &&
+                      bytes_to_jump % (sizeof (png_uint_32)) == 0)
                   {
-                     png_uint_32p dp32 = (png_uint_32p)dp;
-                     png_const_uint_32p sp32 = (png_const_uint_32p)sp;
-                     unsigned int skip = (bytes_to_jump-bytes_to_copy) /
-                        sizeof (png_uint_32);
+                     png_uint_32p dp32 = png_aligncast(png_uint_32p,dp);
+                     png_const_uint_32p sp32 = png_aligncastconst(
+                         png_const_uint_32p, sp);
+                     size_t skip = (bytes_to_jump-bytes_to_copy) /
+                         (sizeof (png_uint_32));
 
                      do
                      {
@@ -3160,7 +3382,7 @@ png_combine_row(png_structp png_ptr, png_bytep dp, int display)
                         do
                         {
                            *dp32++ = *sp32++;
-                           c -= sizeof (png_uint_32);
+                           c -= (sizeof (png_uint_32));
                         }
                         while (c > 0);
 
@@ -3190,10 +3412,11 @@ png_combine_row(png_structp png_ptr, png_bytep dp, int display)
                    */
                   else
                   {
-                     png_uint_16p dp16 = (png_uint_16p)dp;
-                     png_const_uint_16p sp16 = (png_const_uint_16p)sp;
-                     unsigned int skip = (bytes_to_jump-bytes_to_copy) /
-                        sizeof (png_uint_16);
+                     png_uint_16p dp16 = png_aligncast(png_uint_16p, dp);
+                     png_const_uint_16p sp16 = png_aligncastconst(
+                        png_const_uint_16p, sp);
+                     size_t skip = (bytes_to_jump-bytes_to_copy) /
+                        (sizeof (png_uint_16));
 
                      do
                      {
@@ -3201,7 +3424,7 @@ png_combine_row(png_structp png_ptr, png_bytep dp, int display)
                         do
                         {
                            *dp16++ = *sp16++;
-                           c -= sizeof (png_uint_16);
+                           c -= (sizeof (png_uint_16));
                         }
                         while (c > 0);
 
@@ -3223,12 +3446,12 @@ png_combine_row(png_structp png_ptr, png_bytep dp, int display)
                      return;
                   }
                }
-#endif /* PNG_ALIGN_ code */
+#endif /* ALIGN_TYPE code */
 
-               /* The true default - use a png_memcpy: */
+               /* The true default - use a memcpy: */
                for (;;)
                {
-                  png_memcpy(dp, sp, bytes_to_copy);
+                  memcpy(dp, sp, bytes_to_copy);
 
                   if (row_width <= bytes_to_jump)
                      return;
@@ -3237,7 +3460,7 @@ png_combine_row(png_structp png_ptr, png_bytep dp, int display)
                   dp += bytes_to_jump;
                   row_width -= bytes_to_jump;
                   if (bytes_to_copy > row_width)
-                     bytes_to_copy = row_width;
+                     bytes_to_copy = (unsigned int)/*SAFE*/row_width;
                }
          }
 
@@ -3247,13 +3470,13 @@ png_combine_row(png_structp png_ptr, png_bytep dp, int display)
       /* Here if pixel_depth < 8 to check 'end_ptr' below. */
    }
    else
-#endif
+#endif /* READ_INTERLACING */
 
-   /* If here then the switch above wasn't used so just png_memcpy the whole row
+   /* If here then the switch above wasn't used so just memcpy the whole row
     * from the temporary row buffer (notice that this overwrites the end of the
     * destination row if it is a partial byte.)
     */
-   png_memcpy(dp, sp, PNG_ROWBYTES(pixel_depth, row_width));
+   memcpy(dp, sp, PNG_ROWBYTES(pixel_depth, row_width));
 
    /* Restore the overwritten bits from the last byte if necessary. */
    if (end_ptr != NULL)
@@ -3290,7 +3513,7 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
             int j;
 
 #ifdef PNG_READ_PACKSWAP_SUPPORTED
-            if (transformations & PNG_PACKSWAP)
+            if ((transformations & PNG_PACKSWAP) != 0)
             {
                 sshift = (int)((row_info->width + 7) & 0x07);
                 dshift = (int)((final_width + 7) & 0x07);
@@ -3314,8 +3537,9 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
                v = (png_byte)((*sp >> sshift) & 0x01);
                for (j = 0; j < jstop; j++)
                {
-                  *dp &= (png_byte)((0x7f7f >> (7 - dshift)) & 0xff);
-                  *dp |= (png_byte)(v << dshift);
+                  unsigned int tmp = *dp & (0x7f7f >> (7 - dshift));
+                  tmp |= v << dshift;
+                  *dp = (png_byte)(tmp & 0xff);
 
                   if (dshift == s_end)
                   {
@@ -3349,7 +3573,7 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
             png_uint_32 i;
 
 #ifdef PNG_READ_PACKSWAP_SUPPORTED
-            if (transformations & PNG_PACKSWAP)
+            if ((transformations & PNG_PACKSWAP) != 0)
             {
                sshift = (int)(((row_info->width + 3) & 0x03) << 1);
                dshift = (int)(((final_width + 3) & 0x03) << 1);
@@ -3376,8 +3600,9 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
                v = (png_byte)((*sp >> sshift) & 0x03);
                for (j = 0; j < jstop; j++)
                {
-                  *dp &= (png_byte)((0x3f3f >> (6 - dshift)) & 0xff);
-                  *dp |= (png_byte)(v << dshift);
+                  unsigned int tmp = *dp & (0x3f3f >> (6 - dshift));
+                  tmp |= v << dshift;
+                  *dp = (png_byte)(tmp & 0xff);
 
                   if (dshift == s_end)
                   {
@@ -3411,7 +3636,7 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
             int jstop = png_pass_inc[pass];
 
 #ifdef PNG_READ_PACKSWAP_SUPPORTED
-            if (transformations & PNG_PACKSWAP)
+            if ((transformations & PNG_PACKSWAP) != 0)
             {
                sshift = (int)(((row_info->width + 1) & 0x01) << 2);
                dshift = (int)(((final_width + 1) & 0x01) << 2);
@@ -3437,8 +3662,9 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
 
                for (j = 0; j < jstop; j++)
                {
-                  *dp &= (png_byte)((0xf0f >> (4 - dshift)) & 0xff);
-                  *dp |= (png_byte)(v << dshift);
+                  unsigned int tmp = *dp & (0xf0f >> (4 - dshift));
+                  tmp |= v << dshift;
+                  *dp = (png_byte)(tmp & 0xff);
 
                   if (dshift == s_end)
                   {
@@ -3476,14 +3702,14 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
 
             for (i = 0; i < row_info->width; i++)
             {
-               png_byte v[8];
+               png_byte v[8]; /* SAFE; pixel_depth does not exceed 64 */
                int j;
 
-               png_memcpy(v, sp, pixel_bytes);
+               memcpy(v, sp, pixel_bytes);
 
                for (j = 0; j < jstop; j++)
                {
-                  png_memcpy(dp, v, pixel_bytes);
+                  memcpy(dp, v, pixel_bytes);
                   dp -= pixel_bytes;
                }
 
@@ -3500,7 +3726,7 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
    PNG_UNUSED(transformations)  /* Silence compiler warning */
 #endif
 }
-#endif /* PNG_READ_INTERLACING_SUPPORTED */
+#endif /* READ_INTERLACING */
 
 static void
 png_read_filter_row_sub(png_row_infop row_info, png_bytep row,
@@ -3654,74 +3880,22 @@ png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row,
       if (pb < pa) pa = pb, a = b;
       if (pc < pa) a = c;
 
-      c = b;
       a += *row;
       *row++ = (png_byte)a;
    }
 }
 
-#ifdef PNG_ARM_NEON
-
-#ifdef __linux__
-#include <stdio.h>
-#include <elf.h>
-#include <asm/hwcap.h>
-
-static int png_have_hwcap(unsigned cap)
-{
-   FILE *f = fopen("/proc/self/auxv", "r");
-   Elf32_auxv_t aux;
-   int have_cap = 0;
-
-   if (!f)
-      return 0;
-
-   while (fread(&aux, sizeof(aux), 1, f) > 0)
-   {
-      if (aux.a_type == AT_HWCAP &&
-          aux.a_un.a_val & cap)
-      {
-         have_cap = 1;
-         break;
-      }
-   }
-
-   fclose(f);
-
-   return have_cap;
-}
-#endif /* __linux__ */
-
 static void
-png_init_filter_functions_neon(png_structp pp, unsigned int bpp)
-{
-#ifdef __linux__
-   if (!png_have_hwcap(HWCAP_NEON))
-      return;
-#endif
-
-   pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up_neon;
-
-   if (bpp == 3)
-   {
-      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_neon;
-      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_neon;
-      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] = 
-         png_read_filter_row_paeth3_neon;
-   }
-
-   else if (bpp == 4)
-   {
-      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_neon;
-      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_neon;
-      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
-          png_read_filter_row_paeth4_neon;
-   }
-}
-#endif /* PNG_ARM_NEON */
-
-static void
-png_init_filter_functions(png_structp pp)
+png_init_filter_functions(png_structrp pp)
+   /* This function is called once for every PNG image (except for PNG images
+    * that only use PNG_FILTER_VALUE_NONE for all rows) to set the
+    * implementations required to reverse the filtering of PNG rows.  Reversing
+    * the filter is the first transformation performed on the row data.  It is
+    * performed in place, therefore an implementation can be selected based on
+    * the image pixel format.  If the implementation depends on image width then
+    * take care to ensure that it works correctly if the image is interlaced -
+    * interlacing causes the actual row width to vary.
+    */
 {
    unsigned int bpp = (pp->pixel_depth + 7) >> 3;
 
@@ -3735,26 +3909,217 @@ png_init_filter_functions(png_structp pp)
       pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
          png_read_filter_row_paeth_multibyte_pixel;
 
-#ifdef PNG_ARM_NEON
-   png_init_filter_functions_neon(pp, bpp);
+#ifdef PNG_FILTER_OPTIMIZATIONS
+   /* To use this define PNG_FILTER_OPTIMIZATIONS as the name of a function to
+    * call to install hardware optimizations for the above functions; simply
+    * replace whatever elements of the pp->read_filter[] array with a hardware
+    * specific (or, for that matter, generic) optimization.
+    *
+    * To see an example of this examine what configure.ac does when
+    * --enable-arm-neon is specified on the command line.
+    */
+   PNG_FILTER_OPTIMIZATIONS(pp, bpp);
 #endif
 }
 
 void /* PRIVATE */
-png_read_filter_row(png_structp pp, png_row_infop row_info, png_bytep row,
+png_read_filter_row(png_structrp pp, png_row_infop row_info, png_bytep row,
    png_const_bytep prev_row, int filter)
 {
-   if (pp->read_filter[0] == NULL)
-      png_init_filter_functions(pp);
+   /* OPTIMIZATION: DO NOT MODIFY THIS FUNCTION, instead #define
+    * PNG_FILTER_OPTIMIZATIONS to a function that overrides the generic
+    * implementations.  See png_init_filter_functions above.
+    */
    if (filter > PNG_FILTER_VALUE_NONE && filter < PNG_FILTER_VALUE_LAST)
+   {
+      if (pp->read_filter[0] == NULL)
+         png_init_filter_functions(pp);
+
       pp->read_filter[filter-1](row_info, row, prev_row);
+   }
 }
 
 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 void /* PRIVATE */
-png_read_finish_row(png_structp png_ptr)
+png_read_IDAT_data(png_structrp png_ptr, png_bytep output,
+   png_alloc_size_t avail_out)
+{
+   /* Loop reading IDATs and decompressing the result into output[avail_out] */
+   png_ptr->zstream.next_out = output;
+   png_ptr->zstream.avail_out = 0; /* safety: set below */
+
+   if (output == NULL)
+      avail_out = 0;
+
+   do
+   {
+      int ret;
+      png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
+
+      if (png_ptr->zstream.avail_in == 0)
+      {
+         uInt avail_in;
+         png_bytep buffer;
+
+         while (png_ptr->idat_size == 0)
+         {
+            png_crc_finish(png_ptr, 0);
+
+            png_ptr->idat_size = png_read_chunk_header(png_ptr);
+            /* This is an error even in the 'check' case because the code just
+             * consumed a non-IDAT header.
+             */
+            if (png_ptr->chunk_name != png_IDAT)
+               png_error(png_ptr, "Not enough image data");
+         }
+
+         avail_in = png_ptr->IDAT_read_size;
+
+         if (avail_in > png_ptr->idat_size)
+            avail_in = (uInt)png_ptr->idat_size;
+
+         /* A PNG with a gradually increasing IDAT size will defeat this attempt
+          * to minimize memory usage by causing lots of re-allocs, but
+          * realistically doing IDAT_read_size re-allocs is not likely to be a
+          * big problem.
+          */
+         buffer = png_read_buffer(png_ptr, avail_in, 0/*error*/);
+
+         png_crc_read(png_ptr, buffer, avail_in);
+         png_ptr->idat_size -= avail_in;
+
+         png_ptr->zstream.next_in = buffer;
+         png_ptr->zstream.avail_in = avail_in;
+      }
+
+      /* And set up the output side. */
+      if (output != NULL) /* standard read */
+      {
+         uInt out = ZLIB_IO_MAX;
+
+         if (out > avail_out)
+            out = (uInt)avail_out;
+
+         avail_out -= out;
+         png_ptr->zstream.avail_out = out;
+      }
+
+      else /* after last row, checking for end */
+      {
+         png_ptr->zstream.next_out = tmpbuf;
+         png_ptr->zstream.avail_out = (sizeof tmpbuf);
+      }
+
+      /* Use NO_FLUSH; this gives zlib the maximum opportunity to optimize the
+       * process.  If the LZ stream is truncated the sequential reader will
+       * terminally damage the stream, above, by reading the chunk header of the
+       * following chunk (it then exits with png_error).
+       *
+       * TODO: deal more elegantly with truncated IDAT lists.
+       */
+      ret = inflate(&png_ptr->zstream, Z_NO_FLUSH);
+
+      /* Take the unconsumed output back. */
+      if (output != NULL)
+         avail_out += png_ptr->zstream.avail_out;
+
+      else /* avail_out counts the extra bytes */
+         avail_out += (sizeof tmpbuf) - png_ptr->zstream.avail_out;
+
+      png_ptr->zstream.avail_out = 0;
+
+      if (ret == Z_STREAM_END)
+      {
+         /* Do this for safety; we won't read any more into this row. */
+         png_ptr->zstream.next_out = NULL;
+
+         png_ptr->mode |= PNG_AFTER_IDAT;
+         png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
+
+         if (png_ptr->zstream.avail_in > 0 || png_ptr->idat_size > 0)
+            png_chunk_benign_error(png_ptr, "Extra compressed data");
+         break;
+      }
+
+      if (ret != Z_OK)
+      {
+         png_zstream_error(png_ptr, ret);
+
+         if (output != NULL)
+            png_chunk_error(png_ptr, png_ptr->zstream.msg);
+
+         else /* checking */
+         {
+            png_chunk_benign_error(png_ptr, png_ptr->zstream.msg);
+            return;
+         }
+      }
+   } while (avail_out > 0);
+
+   if (avail_out > 0)
+   {
+      /* The stream ended before the image; this is the same as too few IDATs so
+       * should be handled the same way.
+       */
+      if (output != NULL)
+         png_error(png_ptr, "Not enough image data");
+
+      else /* the deflate stream contained extra data */
+         png_chunk_benign_error(png_ptr, "Too much image data");
+   }
+}
+
+void /* PRIVATE */
+png_read_finish_IDAT(png_structrp png_ptr)
+{
+   /* We don't need any more data and the stream should have ended, however the
+    * LZ end code may actually not have been processed.  In this case we must
+    * read it otherwise stray unread IDAT data or, more likely, an IDAT chunk
+    * may still remain to be consumed.
+    */
+   if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
+   {
+      /* The NULL causes png_read_IDAT_data to swallow any remaining bytes in
+       * the compressed stream, but the stream may be damaged too, so even after
+       * this call we may need to terminate the zstream ownership.
+       */
+      png_read_IDAT_data(png_ptr, NULL, 0);
+      png_ptr->zstream.next_out = NULL; /* safety */
+
+      /* Now clear everything out for safety; the following may not have been
+       * done.
+       */
+      if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
+      {
+         png_ptr->mode |= PNG_AFTER_IDAT;
+         png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
+      }
+   }
+
+   /* If the zstream has not been released do it now *and* terminate the reading
+    * of the final IDAT chunk.
+    */
+   if (png_ptr->zowner == png_IDAT)
+   {
+      /* Always do this; the pointers otherwise point into the read buffer. */
+      png_ptr->zstream.next_in = NULL;
+      png_ptr->zstream.avail_in = 0;
+
+      /* Now we no longer own the zstream. */
+      png_ptr->zowner = 0;
+
+      /* The slightly weird semantics of the sequential IDAT reading is that we
+       * are always in or at the end of an IDAT chunk, so we always need to do a
+       * crc_finish here.  If idat_size is non-zero we also need to read the
+       * spurious bytes at the end of the chunk now.
+       */
+      (void)png_crc_finish(png_ptr, png_ptr->idat_size);
+   }
+}
+
+void /* PRIVATE */
+png_read_finish_row(png_structrp png_ptr)
 {
-#ifdef PNG_READ_INTERLACING_SUPPORTED
    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
 
    /* Start of interlace block */
@@ -3768,22 +4133,20 @@ png_read_finish_row(png_structp png_ptr)
 
    /* Offset to next interlace block in the y direction */
    static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
-#endif /* PNG_READ_INTERLACING_SUPPORTED */
 
    png_debug(1, "in png_read_finish_row");
    png_ptr->row_number++;
    if (png_ptr->row_number < png_ptr->num_rows)
       return;
 
-#ifdef PNG_READ_INTERLACING_SUPPORTED
-   if (png_ptr->interlaced)
+   if (png_ptr->interlaced != 0)
    {
       png_ptr->row_number = 0;
 
       /* TO DO: don't do this if prev_row isn't needed (requires
        * read-ahead of the next row's filter byte.
        */
-      png_memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
+      memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
 
       do
       {
@@ -3797,7 +4160,7 @@ png_read_finish_row(png_structp png_ptr)
             png_pass_start[png_ptr->pass]) /
             png_pass_inc[png_ptr->pass];
 
-         if (!(png_ptr->transformations & PNG_INTERLACE))
+         if ((png_ptr->transformations & PNG_INTERLACE) == 0)
          {
             png_ptr->num_rows = (png_ptr->height +
                 png_pass_yinc[png_ptr->pass] - 1 -
@@ -3813,80 +4176,15 @@ png_read_finish_row(png_structp png_ptr)
       if (png_ptr->pass < 7)
          return;
    }
-#endif /* PNG_READ_INTERLACING_SUPPORTED */
-
-   if (!(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
-   {
-      char extra;
-      int ret;
-
-      png_ptr->zstream.next_out = (Byte *)&extra;
-      png_ptr->zstream.avail_out = (uInt)1;
-
-      for (;;)
-      {
-         if (!(png_ptr->zstream.avail_in))
-         {
-            while (!png_ptr->idat_size)
-            {
-               png_crc_finish(png_ptr, 0);
-               png_ptr->idat_size = png_read_chunk_header(png_ptr);
-               if (png_ptr->chunk_name != png_IDAT)
-                  png_error(png_ptr, "Not enough image data");
-            }
-
-            png_ptr->zstream.avail_in = (uInt)png_ptr->zbuf_size;
-            png_ptr->zstream.next_in = png_ptr->zbuf;
-
-            if (png_ptr->zbuf_size > png_ptr->idat_size)
-               png_ptr->zstream.avail_in = (uInt)png_ptr->idat_size;
-
-            png_crc_read(png_ptr, png_ptr->zbuf, png_ptr->zstream.avail_in);
-            png_ptr->idat_size -= png_ptr->zstream.avail_in;
-         }
-
-         ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
-
-         if (ret == Z_STREAM_END)
-         {
-            if (!(png_ptr->zstream.avail_out) || png_ptr->zstream.avail_in ||
-                png_ptr->idat_size)
-               png_warning(png_ptr, "Extra compressed data");
-
-            png_ptr->mode |= PNG_AFTER_IDAT;
-            png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
-            break;
-         }
-
-         if (ret != Z_OK)
-            png_error(png_ptr, png_ptr->zstream.msg ? png_ptr->zstream.msg :
-                "Decompression Error");
-
-         if (!(png_ptr->zstream.avail_out))
-         {
-            png_warning(png_ptr, "Extra compressed data");
-            png_ptr->mode |= PNG_AFTER_IDAT;
-            png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
-            break;
-         }
-
-      }
-      png_ptr->zstream.avail_out = 0;
-   }
-
-   if (png_ptr->idat_size || png_ptr->zstream.avail_in)
-      png_warning(png_ptr, "Extra compression data");
 
-   inflateReset(&png_ptr->zstream);
-
-   png_ptr->mode |= PNG_AFTER_IDAT;
+   /* Here after at the end of the last row of the last pass. */
+   png_read_finish_IDAT(png_ptr);
 }
-#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
+#endif /* SEQUENTIAL_READ */
 
 void /* PRIVATE */
-png_read_start_row(png_structp png_ptr)
+png_read_start_row(png_structrp png_ptr)
 {
-#ifdef PNG_READ_INTERLACING_SUPPORTED
    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
 
    /* Start of interlace block */
@@ -3900,20 +4198,18 @@ png_read_start_row(png_structp png_ptr)
 
    /* Offset to next interlace block in the y direction */
    static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
-#endif
 
    int max_pixel_depth;
    png_size_t row_bytes;
 
    png_debug(1, "in png_read_start_row");
-   png_ptr->zstream.avail_in = 0;
+
 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
    png_init_read_transformations(png_ptr);
 #endif
-#ifdef PNG_READ_INTERLACING_SUPPORTED
-   if (png_ptr->interlaced)
+   if (png_ptr->interlaced != 0)
    {
-      if (!(png_ptr->transformations & PNG_INTERLACE))
+      if ((png_ptr->transformations & PNG_INTERLACE) == 0)
          png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
              png_pass_ystart[0]) / png_pass_yinc[0];
 
@@ -3927,7 +4223,6 @@ png_read_start_row(png_structp png_ptr)
    }
 
    else
-#endif /* PNG_READ_INTERLACING_SUPPORTED */
    {
       png_ptr->num_rows = png_ptr->height;
       png_ptr->iwidth = png_ptr->width;
@@ -3935,7 +4230,7 @@ png_read_start_row(png_structp png_ptr)
 
    max_pixel_depth = png_ptr->pixel_depth;
 
-   /* WARNING: * png_read_transform_info (pngrtran.c) performs a simpliar set of
+   /* WARNING: * png_read_transform_info (pngrtran.c) performs a simpler set of
     * calculations to calculate the final pixel depth, then
     * png_do_read_transforms actually does the transforms.  This means that the
     * code which effectively calculates this value is actually repeated in three
@@ -3946,16 +4241,16 @@ png_read_start_row(png_structp png_ptr)
     * TODO: fix this.
     */
 #ifdef PNG_READ_PACK_SUPPORTED
-   if ((png_ptr->transformations & PNG_PACK) && png_ptr->bit_depth < 8)
+   if ((png_ptr->transformations & PNG_PACK) != 0 && png_ptr->bit_depth < 8)
       max_pixel_depth = 8;
 #endif
 
 #ifdef PNG_READ_EXPAND_SUPPORTED
-   if (png_ptr->transformations & PNG_EXPAND)
+   if ((png_ptr->transformations & PNG_EXPAND) != 0)
    {
       if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
       {
-         if (png_ptr->num_trans)
+         if (png_ptr->num_trans != 0)
             max_pixel_depth = 32;
 
          else
@@ -3967,13 +4262,13 @@ png_read_start_row(png_structp png_ptr)
          if (max_pixel_depth < 8)
             max_pixel_depth = 8;
 
-         if (png_ptr->num_trans)
+         if (png_ptr->num_trans != 0)
             max_pixel_depth *= 2;
       }
 
       else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
       {
-         if (png_ptr->num_trans)
+         if (png_ptr->num_trans != 0)
          {
             max_pixel_depth *= 4;
             max_pixel_depth /= 3;
@@ -3983,13 +4278,13 @@ png_read_start_row(png_structp png_ptr)
 #endif
 
 #ifdef PNG_READ_EXPAND_16_SUPPORTED
-   if (png_ptr->transformations & PNG_EXPAND_16)
+   if ((png_ptr->transformations & PNG_EXPAND_16) != 0)
    {
 #     ifdef PNG_READ_EXPAND_SUPPORTED
          /* In fact it is an error if it isn't supported, but checking is
           * the safe way.
           */
-         if (png_ptr->transformations & PNG_EXPAND)
+         if ((png_ptr->transformations & PNG_EXPAND) != 0)
          {
             if (png_ptr->bit_depth < 16)
                max_pixel_depth *= 2;
@@ -4001,7 +4296,7 @@ png_read_start_row(png_structp png_ptr)
 #endif
 
 #ifdef PNG_READ_FILLER_SUPPORTED
-   if (png_ptr->transformations & (PNG_FILLER))
+   if ((png_ptr->transformations & (PNG_FILLER)) != 0)
    {
       if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
       {
@@ -4025,14 +4320,15 @@ png_read_start_row(png_structp png_ptr)
 #endif
 
 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
-   if (png_ptr->transformations & PNG_GRAY_TO_RGB)
+   if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
    {
       if (
 #ifdef PNG_READ_EXPAND_SUPPORTED
-          (png_ptr->num_trans && (png_ptr->transformations & PNG_EXPAND)) ||
+          (png_ptr->num_trans != 0 &&
+          (png_ptr->transformations & PNG_EXPAND) != 0) ||
 #endif
 #ifdef PNG_READ_FILLER_SUPPORTED
-          (png_ptr->transformations & (PNG_FILLER)) ||
+          (png_ptr->transformations & (PNG_FILLER)) != 0 ||
 #endif
           png_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
       {
@@ -4065,7 +4361,7 @@ png_read_start_row(png_structp png_ptr)
 
 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) && \
 defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
-   if (png_ptr->transformations & PNG_USER_TRANSFORM)
+   if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
    {
       int user_pixel_depth = png_ptr->user_transform_depth *
          png_ptr->user_transform_channels;
@@ -4101,7 +4397,7 @@ defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
      png_free(png_ptr, png_ptr->big_row_buf);
      png_free(png_ptr, png_ptr->big_prev_row);
 
-     if (png_ptr->interlaced)
+     if (png_ptr->interlaced != 0)
         png_ptr->big_row_buf = (png_bytep)png_calloc(png_ptr,
             row_bytes + 48);
 
@@ -4144,7 +4440,7 @@ defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
    if (png_ptr->rowbytes > (PNG_SIZE_MAX - 1))
       png_error(png_ptr, "Row has too many bytes to allocate in memory");
 
-   png_memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
+   memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
 
    png_debug1(3, "width = %u,", png_ptr->width);
    png_debug1(3, "height = %u,", png_ptr->height);
@@ -4154,6 +4450,27 @@ defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
    png_debug1(3, "irowbytes = %lu",
        (unsigned long)PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1);
 
+   /* The sequential reader needs a buffer for IDAT, but the progressive reader
+    * does not, so free the read buffer now regardless; the sequential reader
+    * reallocates it on demand.
+    */
+   if (png_ptr->read_buffer != 0)
+   {
+      png_bytep buffer = png_ptr->read_buffer;
+
+      png_ptr->read_buffer_size = 0;
+      png_ptr->read_buffer = NULL;
+      png_free(png_ptr, buffer);
+   }
+
+   /* Finally claim the zstream for the inflate of the IDAT data, use the bits
+    * value from the stream (note that this will result in a fatal error if the
+    * IDAT stream has a bogus deflate header window_bits value, but this should
+    * not be happening any longer!)
+    */
+   if (png_inflate_claim(png_ptr, png_IDAT) != Z_OK)
+      png_error(png_ptr, png_ptr->zstream.msg);
+
    png_ptr->flags |= PNG_FLAG_ROW_INIT;
 }
-#endif /* PNG_READ_SUPPORTED */
+#endif /* READ */
diff --git a/src/3rdparty/libpng/pngset.c b/src/3rdparty/libpng/pngset.c
index e0118fa..fce3039 100644
--- a/src/3rdparty/libpng/pngset.c
+++ b/src/3rdparty/libpng/pngset.c
@@ -1,8 +1,8 @@
 
 /* pngset.c - storage of image information into info struct
  *
- * Last changed in libpng 1.5.10 [(PENDING RELEASE)]
- * Copyright (c) 1998-2012 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.17 [March 26, 2015]
+ * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
@@ -22,50 +22,51 @@
 
 #ifdef PNG_bKGD_SUPPORTED
 void PNGAPI
-png_set_bKGD(png_structp png_ptr, png_infop info_ptr,
+png_set_bKGD(png_const_structrp png_ptr, png_inforp info_ptr,
     png_const_color_16p background)
 {
    png_debug1(1, "in %s storage function", "bKGD");
 
-   if (png_ptr == NULL || info_ptr == NULL)
+   if (png_ptr == NULL || info_ptr == NULL || background == NULL)
       return;
 
-   png_memcpy(&(info_ptr->background), background, png_sizeof(png_color_16));
+   info_ptr->background = *background;
    info_ptr->valid |= PNG_INFO_bKGD;
 }
 #endif
 
 #ifdef PNG_cHRM_SUPPORTED
 void PNGFAPI
-png_set_cHRM_fixed(png_structp png_ptr, png_infop info_ptr,
+png_set_cHRM_fixed(png_const_structrp png_ptr, png_inforp info_ptr,
     png_fixed_point white_x, png_fixed_point white_y, png_fixed_point red_x,
     png_fixed_point red_y, png_fixed_point green_x, png_fixed_point green_y,
     png_fixed_point blue_x, png_fixed_point blue_y)
 {
+   png_xy xy;
+
    png_debug1(1, "in %s storage function", "cHRM fixed");
 
    if (png_ptr == NULL || info_ptr == NULL)
       return;
 
-#  ifdef PNG_CHECK_cHRM_SUPPORTED
-   if (png_check_cHRM_fixed(png_ptr,
-       white_x, white_y, red_x, red_y, green_x, green_y, blue_x, blue_y))
-#  endif
-   {
-      info_ptr->x_white = white_x;
-      info_ptr->y_white = white_y;
-      info_ptr->x_red   = red_x;
-      info_ptr->y_red   = red_y;
-      info_ptr->x_green = green_x;
-      info_ptr->y_green = green_y;
-      info_ptr->x_blue  = blue_x;
-      info_ptr->y_blue  = blue_y;
-      info_ptr->valid |= PNG_INFO_cHRM;
-   }
+   xy.redx = red_x;
+   xy.redy = red_y;
+   xy.greenx = green_x;
+   xy.greeny = green_y;
+   xy.bluex = blue_x;
+   xy.bluey = blue_y;
+   xy.whitex = white_x;
+   xy.whitey = white_y;
+
+   if (png_colorspace_set_chromaticities(png_ptr, &info_ptr->colorspace, &xy,
+       2/* override with app values*/) != 0)
+      info_ptr->colorspace.flags |= PNG_COLORSPACE_FROM_cHRM;
+
+   png_colorspace_sync_info(png_ptr, info_ptr);
 }
 
 void PNGFAPI
-png_set_cHRM_XYZ_fixed(png_structp png_ptr, png_infop info_ptr,
+png_set_cHRM_XYZ_fixed(png_const_structrp png_ptr, png_inforp info_ptr,
     png_fixed_point int_red_X, png_fixed_point int_red_Y,
     png_fixed_point int_red_Z, png_fixed_point int_green_X,
     png_fixed_point int_green_Y, png_fixed_point int_green_Z,
@@ -73,33 +74,32 @@ png_set_cHRM_XYZ_fixed(png_structp png_ptr, png_infop info_ptr,
     png_fixed_point int_blue_Z)
 {
    png_XYZ XYZ;
-   png_xy xy;
 
    png_debug1(1, "in %s storage function", "cHRM XYZ fixed");
 
    if (png_ptr == NULL || info_ptr == NULL)
       return;
 
-   XYZ.redX = int_red_X;
-   XYZ.redY = int_red_Y;
-   XYZ.redZ = int_red_Z;
-   XYZ.greenX = int_green_X;
-   XYZ.greenY = int_green_Y;
-   XYZ.greenZ = int_green_Z;
-   XYZ.blueX = int_blue_X;
-   XYZ.blueY = int_blue_Y;
-   XYZ.blueZ = int_blue_Z;
-
-   if (png_xy_from_XYZ(&xy, XYZ))
-      png_error(png_ptr, "XYZ values out of representable range");
-
-   png_set_cHRM_fixed(png_ptr, info_ptr, xy.whitex, xy.whitey, xy.redx, xy.redy,
-      xy.greenx, xy.greeny, xy.bluex, xy.bluey);
+   XYZ.red_X = int_red_X;
+   XYZ.red_Y = int_red_Y;
+   XYZ.red_Z = int_red_Z;
+   XYZ.green_X = int_green_X;
+   XYZ.green_Y = int_green_Y;
+   XYZ.green_Z = int_green_Z;
+   XYZ.blue_X = int_blue_X;
+   XYZ.blue_Y = int_blue_Y;
+   XYZ.blue_Z = int_blue_Z;
+
+   if (png_colorspace_set_endpoints(png_ptr, &info_ptr->colorspace,
+       &XYZ, 2) != 0)
+      info_ptr->colorspace.flags |= PNG_COLORSPACE_FROM_cHRM;
+
+   png_colorspace_sync_info(png_ptr, info_ptr);
 }
 
 #  ifdef PNG_FLOATING_POINT_SUPPORTED
 void PNGAPI
-png_set_cHRM(png_structp png_ptr, png_infop info_ptr,
+png_set_cHRM(png_const_structrp png_ptr, png_inforp info_ptr,
     double white_x, double white_y, double red_x, double red_y,
     double green_x, double green_y, double blue_x, double blue_y)
 {
@@ -115,7 +115,7 @@ png_set_cHRM(png_structp png_ptr, png_infop info_ptr,
 }
 
 void PNGAPI
-png_set_cHRM_XYZ(png_structp png_ptr, png_infop info_ptr, double red_X,
+png_set_cHRM_XYZ(png_const_structrp png_ptr, png_inforp info_ptr, double red_X,
     double red_Y, double red_Z, double green_X, double green_Y, double green_Z,
     double blue_X, double blue_Y, double blue_Z)
 {
@@ -130,41 +130,27 @@ png_set_cHRM_XYZ(png_structp png_ptr, png_infop info_ptr, double red_X,
       png_fixed(png_ptr, blue_Y, "cHRM Red Y"),
       png_fixed(png_ptr, blue_Z, "cHRM Red Z"));
 }
-#  endif /* PNG_FLOATING_POINT_SUPPORTED */
+#  endif /* FLOATING_POINT */
 
-#endif /* PNG_cHRM_SUPPORTED */
+#endif /* cHRM */
 
 #ifdef PNG_gAMA_SUPPORTED
 void PNGFAPI
-png_set_gAMA_fixed(png_structp png_ptr, png_infop info_ptr, png_fixed_point
-    file_gamma)
+png_set_gAMA_fixed(png_const_structrp png_ptr, png_inforp info_ptr,
+    png_fixed_point file_gamma)
 {
    png_debug1(1, "in %s storage function", "gAMA");
 
    if (png_ptr == NULL || info_ptr == NULL)
       return;
 
-   /* Changed in libpng-1.5.4 to limit the values to ensure overflow can't
-    * occur.  Since the fixed point representation is assymetrical it is
-    * possible for 1/gamma to overflow the limit of 21474 and this means the
-    * gamma value must be at least 5/100000 and hence at most 20000.0.  For
-    * safety the limits here are a little narrower.  The values are 0.00016 to
-    * 6250.0, which are truly ridiculous gammma values (and will produce
-    * displays that are all black or all white.)
-    */
-   if (file_gamma < 16 || file_gamma > 625000000)
-      png_warning(png_ptr, "Out of range gamma value ignored");
-
-   else
-   {
-      info_ptr->gamma = file_gamma;
-      info_ptr->valid |= PNG_INFO_gAMA;
-   }
+   png_colorspace_set_gamma(png_ptr, &info_ptr->colorspace, file_gamma);
+   png_colorspace_sync_info(png_ptr, info_ptr);
 }
 
 #  ifdef PNG_FLOATING_POINT_SUPPORTED
 void PNGAPI
-png_set_gAMA(png_structp png_ptr, png_infop info_ptr, double file_gamma)
+png_set_gAMA(png_const_structrp png_ptr, png_inforp info_ptr, double file_gamma)
 {
    png_set_gAMA_fixed(png_ptr, info_ptr, png_fixed(png_ptr, file_gamma,
        "png_set_gAMA"));
@@ -174,7 +160,8 @@ png_set_gAMA(png_structp png_ptr, png_infop info_ptr, double file_gamma)
 
 #ifdef PNG_hIST_SUPPORTED
 void PNGAPI
-png_set_hIST(png_structp png_ptr, png_infop info_ptr, png_const_uint_16p hist)
+png_set_hIST(png_const_structrp png_ptr, png_inforp info_ptr,
+    png_const_uint_16p hist)
 {
    int i;
 
@@ -197,26 +184,27 @@ png_set_hIST(png_structp png_ptr, png_infop info_ptr, png_const_uint_16p hist)
    /* Changed from info->num_palette to PNG_MAX_PALETTE_LENGTH in
     * version 1.2.1
     */
-   png_ptr->hist = (png_uint_16p)png_malloc_warn(png_ptr,
-       PNG_MAX_PALETTE_LENGTH * png_sizeof(png_uint_16));
+   info_ptr->hist = png_voidcast(png_uint_16p, png_malloc_warn(png_ptr,
+       PNG_MAX_PALETTE_LENGTH * (sizeof (png_uint_16))));
 
-   if (png_ptr->hist == NULL)
+   if (info_ptr->hist == NULL)
    {
       png_warning(png_ptr, "Insufficient memory for hIST chunk data");
+
       return;
    }
 
+   info_ptr->free_me |= PNG_FREE_HIST;
+
    for (i = 0; i < info_ptr->num_palette; i++)
-      png_ptr->hist[i] = hist[i];
+      info_ptr->hist[i] = hist[i];
 
-   info_ptr->hist = png_ptr->hist;
    info_ptr->valid |= PNG_INFO_hIST;
-   info_ptr->free_me |= PNG_FREE_HIST;
 }
 #endif
 
 void PNGAPI
-png_set_IHDR(png_structp png_ptr, png_infop info_ptr,
+png_set_IHDR(png_const_structrp png_ptr, png_inforp info_ptr,
     png_uint_32 width, png_uint_32 height, int bit_depth,
     int color_type, int interlace_type, int compression_type,
     int filter_type)
@@ -241,32 +229,23 @@ png_set_IHDR(png_structp png_ptr, png_infop info_ptr,
    if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
       info_ptr->channels = 1;
 
-   else if (info_ptr->color_type & PNG_COLOR_MASK_COLOR)
+   else if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
       info_ptr->channels = 3;
 
    else
       info_ptr->channels = 1;
 
-   if (info_ptr->color_type & PNG_COLOR_MASK_ALPHA)
+   if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
       info_ptr->channels++;
 
    info_ptr->pixel_depth = (png_byte)(info_ptr->channels * info_ptr->bit_depth);
 
-   /* Check for potential overflow */
-   if (width >
-       (PNG_UINT_32_MAX >> 3)      /* 8-byte RRGGBBAA pixels */
-       - 48       /* bigrowbuf hack */
-       - 1        /* filter byte */
-       - 7*8      /* rounding of width to multiple of 8 pixels */
-       - 8)       /* extra max_pixel_depth pad */
-      info_ptr->rowbytes = 0;
-   else
-      info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, width);
+   info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, width);
 }
 
 #ifdef PNG_oFFs_SUPPORTED
 void PNGAPI
-png_set_oFFs(png_structp png_ptr, png_infop info_ptr,
+png_set_oFFs(png_const_structrp png_ptr, png_inforp info_ptr,
     png_int_32 offset_x, png_int_32 offset_y, int unit_type)
 {
    png_debug1(1, "in %s storage function", "oFFs");
@@ -283,7 +262,7 @@ png_set_oFFs(png_structp png_ptr, png_infop info_ptr,
 
 #ifdef PNG_pCAL_SUPPORTED
 void PNGAPI
-png_set_pCAL(png_structp png_ptr, png_infop info_ptr,
+png_set_pCAL(png_const_structrp png_ptr, png_inforp info_ptr,
     png_const_charp purpose, png_int_32 X0, png_int_32 X1, int type,
     int nparams, png_const_charp units, png_charpp params)
 {
@@ -292,10 +271,11 @@ png_set_pCAL(png_structp png_ptr, png_infop info_ptr,
 
    png_debug1(1, "in %s storage function", "pCAL");
 
-   if (png_ptr == NULL || info_ptr == NULL)
+   if (png_ptr == NULL || info_ptr == NULL || purpose == NULL || units == NULL
+       || (nparams > 0 && params == NULL))
       return;
 
-   length = png_strlen(purpose) + 1;
+   length = strlen(purpose) + 1;
    png_debug1(3, "allocating purpose for info (%lu bytes)",
        (unsigned long)length);
 
@@ -305,20 +285,28 @@ png_set_pCAL(png_structp png_ptr, png_infop info_ptr,
    if (type < 0 || type > 3)
       png_error(png_ptr, "Invalid pCAL equation type");
 
+   if (nparams < 0 || nparams > 255)
+      png_error(png_ptr, "Invalid pCAL parameter count");
+
    /* Validate params[nparams] */
    for (i=0; i<nparams; ++i)
-      if (!png_check_fp_string(params[i], png_strlen(params[i])))
+   {
+      if (params[i] == NULL ||
+          !png_check_fp_string(params[i], strlen(params[i])))
          png_error(png_ptr, "Invalid format for pCAL parameter");
+   }
 
-   info_ptr->pcal_purpose = (png_charp)png_malloc_warn(png_ptr, length);
+   info_ptr->pcal_purpose = png_voidcast(png_charp,
+       png_malloc_warn(png_ptr, length));
 
    if (info_ptr->pcal_purpose == NULL)
    {
       png_warning(png_ptr, "Insufficient memory for pCAL purpose");
+
       return;
    }
 
-   png_memcpy(info_ptr->pcal_purpose, purpose, length);
+   memcpy(info_ptr->pcal_purpose, purpose, length);
 
    png_debug(3, "storing X0, X1, type, and nparams in info");
    info_ptr->pcal_X0 = X0;
@@ -326,34 +314,37 @@ png_set_pCAL(png_structp png_ptr, png_infop info_ptr,
    info_ptr->pcal_type = (png_byte)type;
    info_ptr->pcal_nparams = (png_byte)nparams;
 
-   length = png_strlen(units) + 1;
+   length = strlen(units) + 1;
    png_debug1(3, "allocating units for info (%lu bytes)",
      (unsigned long)length);
 
-   info_ptr->pcal_units = (png_charp)png_malloc_warn(png_ptr, length);
+   info_ptr->pcal_units = png_voidcast(png_charp,
+      png_malloc_warn(png_ptr, length));
 
    if (info_ptr->pcal_units == NULL)
    {
       png_warning(png_ptr, "Insufficient memory for pCAL units");
+
       return;
    }
 
-   png_memcpy(info_ptr->pcal_units, units, length);
+   memcpy(info_ptr->pcal_units, units, length);
 
-   info_ptr->pcal_params = (png_charpp)png_malloc_warn(png_ptr,
-       (png_size_t)((nparams + 1) * png_sizeof(png_charp)));
+   info_ptr->pcal_params = png_voidcast(png_charpp, png_malloc_warn(png_ptr,
+       (png_size_t)((nparams + 1) * (sizeof (png_charp)))));
 
    if (info_ptr->pcal_params == NULL)
    {
       png_warning(png_ptr, "Insufficient memory for pCAL params");
+
       return;
    }
 
-   png_memset(info_ptr->pcal_params, 0, (nparams + 1) * png_sizeof(png_charp));
+   memset(info_ptr->pcal_params, 0, (nparams + 1) * (sizeof (png_charp)));
 
    for (i = 0; i < nparams; i++)
    {
-      length = png_strlen(params[i]) + 1;
+      length = strlen(params[i]) + 1;
       png_debug2(3, "allocating parameter %d for info (%lu bytes)", i,
           (unsigned long)length);
 
@@ -362,10 +353,11 @@ png_set_pCAL(png_structp png_ptr, png_infop info_ptr,
       if (info_ptr->pcal_params[i] == NULL)
       {
          png_warning(png_ptr, "Insufficient memory for pCAL parameter");
+
          return;
       }
 
-      png_memcpy(info_ptr->pcal_params[i], params[i], length);
+      memcpy(info_ptr->pcal_params[i], params[i], length);
    }
 
    info_ptr->valid |= PNG_INFO_pCAL;
@@ -375,7 +367,7 @@ png_set_pCAL(png_structp png_ptr, png_infop info_ptr,
 
 #ifdef PNG_sCAL_SUPPORTED
 void PNGAPI
-png_set_sCAL_s(png_structp png_ptr, png_infop info_ptr,
+png_set_sCAL_s(png_const_structrp png_ptr, png_inforp info_ptr,
     int unit, png_const_charp swidth, png_const_charp sheight)
 {
    png_size_t lengthw = 0, lengthh = 0;
@@ -391,11 +383,11 @@ png_set_sCAL_s(png_structp png_ptr, png_infop info_ptr,
    if (unit != 1 && unit != 2)
       png_error(png_ptr, "Invalid sCAL unit");
 
-   if (swidth == NULL || (lengthw = png_strlen(swidth)) == 0 ||
+   if (swidth == NULL || (lengthw = strlen(swidth)) == 0 ||
        swidth[0] == 45 /* '-' */ || !png_check_fp_string(swidth, lengthw))
       png_error(png_ptr, "Invalid sCAL width");
 
-   if (sheight == NULL || (lengthh = png_strlen(sheight)) == 0 ||
+   if (sheight == NULL || (lengthh = strlen(sheight)) == 0 ||
        sheight[0] == 45 /* '-' */ || !png_check_fp_string(sheight, lengthh))
       png_error(png_ptr, "Invalid sCAL height");
 
@@ -405,21 +397,24 @@ png_set_sCAL_s(png_structp png_ptr, png_infop info_ptr,
 
    png_debug1(3, "allocating unit for info (%u bytes)", (unsigned int)lengthw);
 
-   info_ptr->scal_s_width = (png_charp)png_malloc_warn(png_ptr, lengthw);
+   info_ptr->scal_s_width = png_voidcast(png_charp,
+      png_malloc_warn(png_ptr, lengthw));
 
    if (info_ptr->scal_s_width == NULL)
    {
       png_warning(png_ptr, "Memory allocation failed while processing sCAL");
+
       return;
    }
 
-   png_memcpy(info_ptr->scal_s_width, swidth, lengthw);
+   memcpy(info_ptr->scal_s_width, swidth, lengthw);
 
    ++lengthh;
 
    png_debug1(3, "allocating unit for info (%u bytes)", (unsigned int)lengthh);
 
-   info_ptr->scal_s_height = (png_charp)png_malloc_warn(png_ptr, lengthh);
+   info_ptr->scal_s_height = png_voidcast(png_charp,
+      png_malloc_warn(png_ptr, lengthh));
 
    if (info_ptr->scal_s_height == NULL)
    {
@@ -427,10 +422,11 @@ png_set_sCAL_s(png_structp png_ptr, png_infop info_ptr,
       info_ptr->scal_s_width = NULL;
 
       png_warning(png_ptr, "Memory allocation failed while processing sCAL");
+
       return;
    }
 
-   png_memcpy(info_ptr->scal_s_height, sheight, lengthh);
+   memcpy(info_ptr->scal_s_height, sheight, lengthh);
 
    info_ptr->valid |= PNG_INFO_sCAL;
    info_ptr->free_me |= PNG_FREE_SCAL;
@@ -438,8 +434,8 @@ png_set_sCAL_s(png_structp png_ptr, png_infop info_ptr,
 
 #  ifdef PNG_FLOATING_POINT_SUPPORTED
 void PNGAPI
-png_set_sCAL(png_structp png_ptr, png_infop info_ptr, int unit, double width,
-    double height)
+png_set_sCAL(png_const_structrp png_ptr, png_inforp info_ptr, int unit,
+    double width, double height)
 {
    png_debug1(1, "in %s storage function", "sCAL");
 
@@ -456,9 +452,9 @@ png_set_sCAL(png_structp png_ptr, png_infop info_ptr, int unit, double width,
       char swidth[PNG_sCAL_MAX_DIGITS+1];
       char sheight[PNG_sCAL_MAX_DIGITS+1];
 
-      png_ascii_from_fp(png_ptr, swidth, sizeof swidth, width,
+      png_ascii_from_fp(png_ptr, swidth, (sizeof swidth), width,
          PNG_sCAL_PRECISION);
-      png_ascii_from_fp(png_ptr, sheight, sizeof sheight, height,
+      png_ascii_from_fp(png_ptr, sheight, (sizeof sheight), height,
          PNG_sCAL_PRECISION);
 
       png_set_sCAL_s(png_ptr, info_ptr, unit, swidth, sheight);
@@ -468,7 +464,7 @@ png_set_sCAL(png_structp png_ptr, png_infop info_ptr, int unit, double width,
 
 #  ifdef PNG_FIXED_POINT_SUPPORTED
 void PNGAPI
-png_set_sCAL_fixed(png_structp png_ptr, png_infop info_ptr, int unit,
+png_set_sCAL_fixed(png_const_structrp png_ptr, png_inforp info_ptr, int unit,
     png_fixed_point width, png_fixed_point height)
 {
    png_debug1(1, "in %s storage function", "sCAL");
@@ -486,8 +482,8 @@ png_set_sCAL_fixed(png_structp png_ptr, png_infop info_ptr, int unit,
       char swidth[PNG_sCAL_MAX_DIGITS+1];
       char sheight[PNG_sCAL_MAX_DIGITS+1];
 
-      png_ascii_from_fixed(png_ptr, swidth, sizeof swidth, width);
-      png_ascii_from_fixed(png_ptr, sheight, sizeof sheight, height);
+      png_ascii_from_fixed(png_ptr, swidth, (sizeof swidth), width);
+      png_ascii_from_fixed(png_ptr, sheight, (sizeof sheight), height);
 
       png_set_sCAL_s(png_ptr, info_ptr, unit, swidth, sheight);
    }
@@ -497,7 +493,7 @@ png_set_sCAL_fixed(png_structp png_ptr, png_infop info_ptr, int unit,
 
 #ifdef PNG_pHYs_SUPPORTED
 void PNGAPI
-png_set_pHYs(png_structp png_ptr, png_infop info_ptr,
+png_set_pHYs(png_const_structrp png_ptr, png_inforp info_ptr,
     png_uint_32 res_x, png_uint_32 res_y, int unit_type)
 {
    png_debug1(1, "in %s storage function", "pHYs");
@@ -513,7 +509,7 @@ png_set_pHYs(png_structp png_ptr, png_infop info_ptr,
 #endif
 
 void PNGAPI
-png_set_PLTE(png_structp png_ptr, png_infop info_ptr,
+png_set_PLTE(png_structrp png_ptr, png_inforp info_ptr,
     png_const_colorp palette, int num_palette)
 {
 
@@ -530,13 +526,27 @@ png_set_PLTE(png_structp png_ptr, png_infop info_ptr,
       else
       {
          png_warning(png_ptr, "Invalid palette length");
+
          return;
       }
    }
 
+   if ((num_palette > 0 && palette == NULL) ||
+      (num_palette == 0
+#        ifdef PNG_MNG_FEATURES_SUPPORTED
+            && (png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0
+#        endif
+      ))
+   {
+      png_error(png_ptr, "Invalid palette");
+   }
+
    /* It may not actually be necessary to set png_ptr->palette here;
     * we do it for backward compatibility with the way the png_handle_tRNS
     * function used to do the allocation.
+    *
+    * 1.6.0: the above statement appears to be incorrect; something has to set
+    * the palette inside png_struct on read.
     */
    png_free_data(png_ptr, info_ptr, PNG_FREE_PLTE, 0);
 
@@ -544,10 +554,11 @@ png_set_PLTE(png_structp png_ptr, png_infop info_ptr,
     * of num_palette entries, in case of an invalid PNG file that has
     * too-large sample values.
     */
-   png_ptr->palette = (png_colorp)png_calloc(png_ptr,
-       PNG_MAX_PALETTE_LENGTH * png_sizeof(png_color));
+   png_ptr->palette = png_voidcast(png_colorp, png_calloc(png_ptr,
+       PNG_MAX_PALETTE_LENGTH * (sizeof (png_color))));
 
-   png_memcpy(png_ptr->palette, palette, num_palette * png_sizeof(png_color));
+   if (num_palette > 0)
+      memcpy(png_ptr->palette, palette, num_palette * (sizeof (png_color)));
    info_ptr->palette = png_ptr->palette;
    info_ptr->num_palette = png_ptr->num_palette = (png_uint_16)num_palette;
 
@@ -558,34 +569,34 @@ png_set_PLTE(png_structp png_ptr, png_infop info_ptr,
 
 #ifdef PNG_sBIT_SUPPORTED
 void PNGAPI
-png_set_sBIT(png_structp png_ptr, png_infop info_ptr,
+png_set_sBIT(png_const_structrp png_ptr, png_inforp info_ptr,
     png_const_color_8p sig_bit)
 {
    png_debug1(1, "in %s storage function", "sBIT");
 
-   if (png_ptr == NULL || info_ptr == NULL)
+   if (png_ptr == NULL || info_ptr == NULL || sig_bit == NULL)
       return;
 
-   png_memcpy(&(info_ptr->sig_bit), sig_bit, png_sizeof(png_color_8));
+   info_ptr->sig_bit = *sig_bit;
    info_ptr->valid |= PNG_INFO_sBIT;
 }
 #endif
 
 #ifdef PNG_sRGB_SUPPORTED
 void PNGAPI
-png_set_sRGB(png_structp png_ptr, png_infop info_ptr, int srgb_intent)
+png_set_sRGB(png_const_structrp png_ptr, png_inforp info_ptr, int srgb_intent)
 {
    png_debug1(1, "in %s storage function", "sRGB");
 
    if (png_ptr == NULL || info_ptr == NULL)
       return;
 
-   info_ptr->srgb_intent = (png_byte)srgb_intent;
-   info_ptr->valid |= PNG_INFO_sRGB;
+   (void)png_colorspace_set_sRGB(png_ptr, &info_ptr->colorspace, srgb_intent);
+   png_colorspace_sync_info(png_ptr, info_ptr);
 }
 
 void PNGAPI
-png_set_sRGB_gAMA_and_cHRM(png_structp png_ptr, png_infop info_ptr,
+png_set_sRGB_gAMA_and_cHRM(png_const_structrp png_ptr, png_inforp info_ptr,
     int srgb_intent)
 {
    png_debug1(1, "in %s storage function", "sRGB_gAMA_and_cHRM");
@@ -593,28 +604,22 @@ png_set_sRGB_gAMA_and_cHRM(png_structp png_ptr, png_infop info_ptr,
    if (png_ptr == NULL || info_ptr == NULL)
       return;
 
-   png_set_sRGB(png_ptr, info_ptr, srgb_intent);
-
-#  ifdef PNG_gAMA_SUPPORTED
-   png_set_gAMA_fixed(png_ptr, info_ptr, PNG_GAMMA_sRGB_INVERSE);
-#  endif
+   if (png_colorspace_set_sRGB(png_ptr, &info_ptr->colorspace,
+       srgb_intent) != 0)
+   {
+      /* This causes the gAMA and cHRM to be written too */
+      info_ptr->colorspace.flags |=
+         PNG_COLORSPACE_FROM_gAMA|PNG_COLORSPACE_FROM_cHRM;
+   }
 
-#  ifdef PNG_cHRM_SUPPORTED
-   png_set_cHRM_fixed(png_ptr, info_ptr,
-      /* color      x       y */
-      /* white */ 31270, 32900,
-      /* red   */ 64000, 33000,
-      /* green */ 30000, 60000,
-      /* blue  */ 15000,  6000
-   );
-#  endif /* cHRM */
+   png_colorspace_sync_info(png_ptr, info_ptr);
 }
 #endif /* sRGB */
 
 
 #ifdef PNG_iCCP_SUPPORTED
 void PNGAPI
-png_set_iCCP(png_structp png_ptr, png_infop info_ptr,
+png_set_iCCP(png_const_structrp png_ptr, png_inforp info_ptr,
     png_const_charp name, int compression_type,
     png_const_bytep profile, png_uint_32 proflen)
 {
@@ -627,37 +632,61 @@ png_set_iCCP(png_structp png_ptr, png_infop info_ptr,
    if (png_ptr == NULL || info_ptr == NULL || name == NULL || profile == NULL)
       return;
 
-   length = png_strlen(name)+1;
-   new_iccp_name = (png_charp)png_malloc_warn(png_ptr, length);
+   if (compression_type != PNG_COMPRESSION_TYPE_BASE)
+      png_app_error(png_ptr, "Invalid iCCP compression method");
+
+   /* Set the colorspace first because this validates the profile; do not
+    * override previously set app cHRM or gAMA here (because likely as not the
+    * application knows better than libpng what the correct values are.)  Pass
+    * the info_ptr color_type field to png_colorspace_set_ICC because in the
+    * write case it has not yet been stored in png_ptr.
+    */
+   {
+      int result = png_colorspace_set_ICC(png_ptr, &info_ptr->colorspace, name,
+         proflen, profile, info_ptr->color_type);
+
+      png_colorspace_sync_info(png_ptr, info_ptr);
+
+      /* Don't do any of the copying if the profile was bad, or inconsistent. */
+      if (result == 0)
+         return;
+
+      /* But do write the gAMA and cHRM chunks from the profile. */
+      info_ptr->colorspace.flags |=
+         PNG_COLORSPACE_FROM_gAMA|PNG_COLORSPACE_FROM_cHRM;
+   }
+
+   length = strlen(name)+1;
+   new_iccp_name = png_voidcast(png_charp, png_malloc_warn(png_ptr, length));
 
    if (new_iccp_name == NULL)
    {
-        png_warning(png_ptr, "Insufficient memory to process iCCP chunk");
+      png_benign_error(png_ptr, "Insufficient memory to process iCCP chunk");
+
       return;
    }
 
-   png_memcpy(new_iccp_name, name, length);
-   new_iccp_profile = (png_bytep)png_malloc_warn(png_ptr, proflen);
+   memcpy(new_iccp_name, name, length);
+   new_iccp_profile = png_voidcast(png_bytep,
+      png_malloc_warn(png_ptr, proflen));
 
    if (new_iccp_profile == NULL)
    {
-      png_free (png_ptr, new_iccp_name);
-      png_warning(png_ptr,
+      png_free(png_ptr, new_iccp_name);
+      new_iccp_name = NULL;
+      png_benign_error(png_ptr,
           "Insufficient memory to process iCCP profile");
+
       return;
    }
 
-   png_memcpy(new_iccp_profile, profile, (png_size_t)proflen);
+   memcpy(new_iccp_profile, profile, proflen);
 
    png_free_data(png_ptr, info_ptr, PNG_FREE_ICCP, 0);
 
    info_ptr->iccp_proflen = proflen;
    info_ptr->iccp_name = new_iccp_name;
    info_ptr->iccp_profile = new_iccp_profile;
-   /* Compression is always zero but is here so the API and info structure
-    * does not have to change if we introduce multiple compression types
-    */
-   info_ptr->iccp_compression = (png_byte)compression_type;
    info_ptr->free_me |= PNG_FREE_ICCP;
    info_ptr->valid |= PNG_INFO_iCCP;
 }
@@ -665,18 +694,18 @@ png_set_iCCP(png_structp png_ptr, png_infop info_ptr,
 
 #ifdef PNG_TEXT_SUPPORTED
 void PNGAPI
-png_set_text(png_structp png_ptr, png_infop info_ptr, png_const_textp text_ptr,
-    int num_text)
+png_set_text(png_const_structrp png_ptr, png_inforp info_ptr,
+    png_const_textp text_ptr, int num_text)
 {
    int ret;
    ret = png_set_text_2(png_ptr, info_ptr, text_ptr, num_text);
 
-   if (ret)
+   if (ret != 0)
       png_error(png_ptr, "Insufficient memory to store text");
 }
 
 int /* PRIVATE */
-png_set_text_2(png_structp png_ptr, png_infop info_ptr,
+png_set_text_2(png_const_structrp png_ptr, png_inforp info_ptr,
     png_const_textp text_ptr, int num_text)
 {
    int i;
@@ -684,63 +713,63 @@ png_set_text_2(png_structp png_ptr, png_infop info_ptr,
    png_debug1(1, "in %lx storage function", png_ptr == NULL ? "unexpected" :
       (unsigned long)png_ptr->chunk_name);
 
-   if (png_ptr == NULL || info_ptr == NULL || num_text == 0)
+   if (png_ptr == NULL || info_ptr == NULL || num_text <= 0 || text_ptr == NULL)
       return(0);
 
    /* Make sure we have enough space in the "text" array in info_struct
-    * to hold all of the incoming text_ptr objects.
+    * to hold all of the incoming text_ptr objects.  This compare can't overflow
+    * because max_text >= num_text (anyway, subtract of two positive integers
+    * can't overflow in any case.)
     */
-   if (info_ptr->num_text + num_text > info_ptr->max_text)
+   if (num_text > info_ptr->max_text - info_ptr->num_text)
    {
-      int old_max_text = info_ptr->max_text;
       int old_num_text = info_ptr->num_text;
+      int max_text;
+      png_textp new_text = NULL;
 
-      if (info_ptr->text != NULL)
+      /* Calculate an appropriate max_text, checking for overflow. */
+      max_text = old_num_text;
+      if (num_text <= INT_MAX - max_text)
       {
-         png_textp old_text;
-
-         info_ptr->max_text = info_ptr->num_text + num_text + 8;
-         old_text = info_ptr->text;
+         max_text += num_text;
 
-         info_ptr->text = (png_textp)png_malloc_warn(png_ptr,
-            (png_size_t)(info_ptr->max_text * png_sizeof(png_text)));
+         /* Round up to a multiple of 8 */
+         if (max_text < INT_MAX-8)
+            max_text = (max_text + 8) & ~0x7;
 
-         if (info_ptr->text == NULL)
-         {
-            /* Restore to previous condition */
-            info_ptr->max_text = old_max_text;
-            info_ptr->text = old_text;
-            return(1);
-         }
-
-         png_memcpy(info_ptr->text, old_text, (png_size_t)(old_max_text *
-             png_sizeof(png_text)));
-         png_free(png_ptr, old_text);
+         else
+            max_text = INT_MAX;
+
+         /* Now allocate a new array and copy the old members in; this does all
+          * the overflow checks.
+          */
+         new_text = png_voidcast(png_textp,png_realloc_array(png_ptr,
+            info_ptr->text, old_num_text, max_text-old_num_text,
+            sizeof *new_text));
       }
 
-      else
+      if (new_text == NULL)
       {
-         info_ptr->max_text = num_text + 8;
-         info_ptr->num_text = 0;
-         info_ptr->text = (png_textp)png_malloc_warn(png_ptr,
-             (png_size_t)(info_ptr->max_text * png_sizeof(png_text)));
-         if (info_ptr->text == NULL)
-         {
-            /* Restore to previous condition */
-            info_ptr->num_text = old_num_text;
-            info_ptr->max_text = old_max_text;
-            return(1);
-         }
-         info_ptr->free_me |= PNG_FREE_TEXT;
+         png_chunk_report(png_ptr, "too many text chunks",
+            PNG_CHUNK_WRITE_ERROR);
+
+         return 1;
       }
 
-      png_debug1(3, "allocated %d entries for info_ptr->text",
-          info_ptr->max_text);
+      png_free(png_ptr, info_ptr->text);
+
+      info_ptr->text = new_text;
+      info_ptr->free_me |= PNG_FREE_TEXT;
+      info_ptr->max_text = max_text;
+      /* num_text is adjusted below as the entries are copied in */
+
+      png_debug1(3, "allocated %d entries for info_ptr->text", max_text);
    }
+
    for (i = 0; i < num_text; i++)
    {
-      png_size_t text_length, key_len;
-      png_size_t lang_len, lang_key_len;
+      size_t text_length, key_len;
+      size_t lang_len, lang_key_len;
       png_textp textp = &(info_ptr->text[info_ptr->num_text]);
 
       if (text_ptr[i].key == NULL)
@@ -749,11 +778,12 @@ png_set_text_2(png_structp png_ptr, png_infop info_ptr,
       if (text_ptr[i].compression < PNG_TEXT_COMPRESSION_NONE ||
           text_ptr[i].compression >= PNG_TEXT_COMPRESSION_LAST)
       {
-         png_warning(png_ptr, "text compression mode is out of range");
+         png_chunk_report(png_ptr, "text compression mode is out of range",
+            PNG_CHUNK_WRITE_ERROR);
          continue;
       }
 
-      key_len = png_strlen(text_ptr[i].key);
+      key_len = strlen(text_ptr[i].key);
 
       if (text_ptr[i].compression <= 0)
       {
@@ -767,20 +797,21 @@ png_set_text_2(png_structp png_ptr, png_infop info_ptr,
          /* Set iTXt data */
 
          if (text_ptr[i].lang != NULL)
-            lang_len = png_strlen(text_ptr[i].lang);
+            lang_len = strlen(text_ptr[i].lang);
 
          else
             lang_len = 0;
 
          if (text_ptr[i].lang_key != NULL)
-            lang_key_len = png_strlen(text_ptr[i].lang_key);
+            lang_key_len = strlen(text_ptr[i].lang_key);
 
          else
             lang_key_len = 0;
       }
-#  else /* PNG_iTXt_SUPPORTED */
+#  else /* iTXt */
       {
-         png_warning(png_ptr, "iTXt chunk not supported");
+         png_chunk_report(png_ptr, "iTXt chunk not supported",
+            PNG_CHUNK_WRITE_ERROR);
          continue;
       }
 #  endif
@@ -799,32 +830,36 @@ png_set_text_2(png_structp png_ptr, png_infop info_ptr,
 
       else
       {
-         text_length = png_strlen(text_ptr[i].text);
+         text_length = strlen(text_ptr[i].text);
          textp->compression = text_ptr[i].compression;
       }
 
-      textp->key = (png_charp)png_malloc_warn(png_ptr,
-          (png_size_t)
-          (key_len + text_length + lang_len + lang_key_len + 4));
+      textp->key = png_voidcast(png_charp,png_malloc_base(png_ptr,
+          key_len + text_length + lang_len + lang_key_len + 4));
 
       if (textp->key == NULL)
-         return(1);
+      {
+         png_chunk_report(png_ptr, "text chunk: out of memory",
+               PNG_CHUNK_WRITE_ERROR);
+
+         return 1;
+      }
 
       png_debug2(2, "Allocated %lu bytes at %p in png_set_text",
           (unsigned long)(png_uint_32)
           (key_len + lang_len + lang_key_len + text_length + 4),
           textp->key);
 
-      png_memcpy(textp->key, text_ptr[i].key,(png_size_t)(key_len));
+      memcpy(textp->key, text_ptr[i].key, key_len);
       *(textp->key + key_len) = '\0';
 
       if (text_ptr[i].compression > 0)
       {
          textp->lang = textp->key + key_len + 1;
-         png_memcpy(textp->lang, text_ptr[i].lang, lang_len);
+         memcpy(textp->lang, text_ptr[i].lang, lang_len);
          *(textp->lang + lang_len) = '\0';
          textp->lang_key = textp->lang + lang_len + 1;
-         png_memcpy(textp->lang_key, text_ptr[i].lang_key, lang_key_len);
+         memcpy(textp->lang_key, text_ptr[i].lang_key, lang_key_len);
          *(textp->lang_key + lang_key_len) = '\0';
          textp->text = textp->lang_key + lang_key_len + 1;
       }
@@ -836,9 +871,8 @@ png_set_text_2(png_structp png_ptr, png_infop info_ptr,
          textp->text = textp->key + key_len + 1;
       }
 
-      if (text_length)
-         png_memcpy(textp->text, text_ptr[i].text,
-             (png_size_t)(text_length));
+      if (text_length != 0)
+         memcpy(textp->text, text_ptr[i].text, text_length);
 
       *(textp->text + text_length) = '\0';
 
@@ -859,18 +893,20 @@ png_set_text_2(png_structp png_ptr, png_infop info_ptr,
       info_ptr->num_text++;
       png_debug1(3, "transferred text chunk %d", info_ptr->num_text);
    }
+
    return(0);
 }
 #endif
 
 #ifdef PNG_tIME_SUPPORTED
 void PNGAPI
-png_set_tIME(png_structp png_ptr, png_infop info_ptr, png_const_timep mod_time)
+png_set_tIME(png_const_structrp png_ptr, png_inforp info_ptr,
+    png_const_timep mod_time)
 {
    png_debug1(1, "in %s storage function", "tIME");
 
-   if (png_ptr == NULL || info_ptr == NULL ||
-       (png_ptr->mode & PNG_WROTE_tIME))
+   if (png_ptr == NULL || info_ptr == NULL || mod_time == NULL ||
+       (png_ptr->mode & PNG_WROTE_tIME) != 0)
       return;
 
    if (mod_time->month == 0   || mod_time->month > 12  ||
@@ -879,22 +915,24 @@ png_set_tIME(png_structp png_ptr, png_infop info_ptr, png_const_timep mod_time)
        mod_time->second > 60)
    {
       png_warning(png_ptr, "Ignoring invalid time value");
+
       return;
    }
 
-   png_memcpy(&(info_ptr->mod_time), mod_time, png_sizeof(png_time));
+   info_ptr->mod_time = *mod_time;
    info_ptr->valid |= PNG_INFO_tIME;
 }
 #endif
 
 #ifdef PNG_tRNS_SUPPORTED
 void PNGAPI
-png_set_tRNS(png_structp png_ptr, png_infop info_ptr,
+png_set_tRNS(png_structrp png_ptr, png_inforp info_ptr,
     png_const_bytep trans_alpha, int num_trans, png_const_color_16p trans_color)
 {
    png_debug1(1, "in %s storage function", "tRNS");
 
    if (png_ptr == NULL || info_ptr == NULL)
+
       return;
 
    if (trans_alpha != NULL)
@@ -902,33 +940,41 @@ png_set_tRNS(png_structp png_ptr, png_infop info_ptr,
        /* It may not actually be necessary to set png_ptr->trans_alpha here;
         * we do it for backward compatibility with the way the png_handle_tRNS
         * function used to do the allocation.
+        *
+        * 1.6.0: The above statement is incorrect; png_handle_tRNS effectively
+        * relies on png_set_tRNS storing the information in png_struct
+        * (otherwise it won't be there for the code in pngrtran.c).
         */
 
        png_free_data(png_ptr, info_ptr, PNG_FREE_TRNS, 0);
 
        /* Changed from num_trans to PNG_MAX_PALETTE_LENGTH in version 1.2.1 */
-       png_ptr->trans_alpha = info_ptr->trans_alpha =
-           (png_bytep)png_malloc(png_ptr, (png_size_t)PNG_MAX_PALETTE_LENGTH);
+       png_ptr->trans_alpha = info_ptr->trans_alpha = png_voidcast(png_bytep,
+         png_malloc(png_ptr, PNG_MAX_PALETTE_LENGTH));
 
        if (num_trans > 0 && num_trans <= PNG_MAX_PALETTE_LENGTH)
-          png_memcpy(info_ptr->trans_alpha, trans_alpha, (png_size_t)num_trans);
+          memcpy(info_ptr->trans_alpha, trans_alpha, (png_size_t)num_trans);
    }
 
    if (trans_color != NULL)
    {
-      int sample_max = (1 << info_ptr->bit_depth);
-
-      if ((info_ptr->color_type == PNG_COLOR_TYPE_GRAY &&
-          (int)trans_color->gray > sample_max) ||
-          (info_ptr->color_type == PNG_COLOR_TYPE_RGB &&
-          ((int)trans_color->red > sample_max ||
-          (int)trans_color->green > sample_max ||
-          (int)trans_color->blue > sample_max)))
-         png_warning(png_ptr,
-            "tRNS chunk has out-of-range samples for bit_depth");
+#ifdef PNG_WARNINGS_SUPPORTED
+      if (info_ptr->bit_depth < 16)
+      {
+         int sample_max = (1 << info_ptr->bit_depth) - 1;
+
+         if ((info_ptr->color_type == PNG_COLOR_TYPE_GRAY &&
+             trans_color->gray > sample_max) ||
+             (info_ptr->color_type == PNG_COLOR_TYPE_RGB &&
+             (trans_color->red > sample_max ||
+             trans_color->green > sample_max ||
+             trans_color->blue > sample_max)))
+            png_warning(png_ptr,
+               "tRNS chunk has out-of-range samples for bit_depth");
+      }
+#endif
 
-      png_memcpy(&(info_ptr->trans_color), trans_color,
-         png_sizeof(png_color_16));
+      info_ptr->trans_color = *trans_color;
 
       if (num_trans == 0)
          num_trans = 1;
@@ -946,8 +992,8 @@ png_set_tRNS(png_structp png_ptr, png_infop info_ptr,
 
 #ifdef PNG_sPLT_SUPPORTED
 void PNGAPI
-png_set_sPLT(png_structp png_ptr,
-    png_infop info_ptr, png_const_sPLT_tp entries, int nentries)
+png_set_sPLT(png_const_structrp png_ptr,
+    png_inforp info_ptr, png_const_sPLT_tp entries, int nentries)
 /*
  *  entries        - array of png_sPLT_t structures
  *                   to be added to the list of palettes
@@ -958,220 +1004,462 @@ png_set_sPLT(png_structp png_ptr,
  */
 {
    png_sPLT_tp np;
-   int i;
 
-   if (png_ptr == NULL || info_ptr == NULL)
+   if (png_ptr == NULL || info_ptr == NULL || nentries <= 0 || entries == NULL)
       return;
 
-   np = (png_sPLT_tp)png_malloc_warn(png_ptr,
-       (info_ptr->splt_palettes_num + nentries) *
-       (png_size_t)png_sizeof(png_sPLT_t));
+   /* Use the internal realloc function, which checks for all the possible
+    * overflows.  Notice that the parameters are (int) and (size_t)
+    */
+   np = png_voidcast(png_sPLT_tp,png_realloc_array(png_ptr,
+      info_ptr->splt_palettes, info_ptr->splt_palettes_num, nentries,
+      sizeof *np));
 
    if (np == NULL)
    {
-      png_warning(png_ptr, "No memory for sPLT palettes");
+      /* Out of memory or too many chunks */
+      png_chunk_report(png_ptr, "too many sPLT chunks", PNG_CHUNK_WRITE_ERROR);
+
       return;
    }
 
-   png_memcpy(np, info_ptr->splt_palettes,
-       info_ptr->splt_palettes_num * png_sizeof(png_sPLT_t));
-
    png_free(png_ptr, info_ptr->splt_palettes);
-   info_ptr->splt_palettes=NULL;
+   info_ptr->splt_palettes = np;
+   info_ptr->free_me |= PNG_FREE_SPLT;
 
-   for (i = 0; i < nentries; i++)
+   np += info_ptr->splt_palettes_num;
+
+   do
    {
-      png_sPLT_tp to = np + info_ptr->splt_palettes_num + i;
-      png_const_sPLT_tp from = entries + i;
       png_size_t length;
 
-      length = png_strlen(from->name) + 1;
-      to->name = (png_charp)png_malloc_warn(png_ptr, length);
-
-      if (to->name == NULL)
+      /* Skip invalid input entries */
+      if (entries->name == NULL || entries->entries == NULL)
       {
-         png_warning(png_ptr,
-             "Out of memory while processing sPLT chunk");
+         /* png_handle_sPLT doesn't do this, so this is an app error */
+         png_app_error(png_ptr, "png_set_sPLT: invalid sPLT");
+         /* Just skip the invalid entry */
          continue;
       }
 
-      png_memcpy(to->name, from->name, length);
-      to->entries = (png_sPLT_entryp)png_malloc_warn(png_ptr,
-          from->nentries * png_sizeof(png_sPLT_entry));
+      np->depth = entries->depth;
+
+      /* In the event of out-of-memory just return - there's no point keeping
+       * on trying to add sPLT chunks.
+       */
+      length = strlen(entries->name) + 1;
+      np->name = png_voidcast(png_charp, png_malloc_base(png_ptr, length));
+
+      if (np->name == NULL)
+         break;
+
+      memcpy(np->name, entries->name, length);
 
-      if (to->entries == NULL)
+      /* IMPORTANT: we have memory now that won't get freed if something else
+       * goes wrong; this code must free it.  png_malloc_array produces no
+       * warnings; use a png_chunk_report (below) if there is an error.
+       */
+      np->entries = png_voidcast(png_sPLT_entryp, png_malloc_array(png_ptr,
+          entries->nentries, sizeof (png_sPLT_entry)));
+
+      if (np->entries == NULL)
       {
-         png_warning(png_ptr,
-             "Out of memory while processing sPLT chunk");
-         png_free(png_ptr, to->name);
-         to->name = NULL;
-         continue;
+         png_free(png_ptr, np->name);
+         np->name = NULL;
+         break;
       }
 
-      png_memcpy(to->entries, from->entries,
-          from->nentries * png_sizeof(png_sPLT_entry));
+      np->nentries = entries->nentries;
+      /* This multiply can't overflow because png_malloc_array has already
+       * checked it when doing the allocation.
+       */
+      memcpy(np->entries, entries->entries,
+         entries->nentries * sizeof (png_sPLT_entry));
+
+      /* Note that 'continue' skips the advance of the out pointer and out
+       * count, so an invalid entry is not added.
+       */
+      info_ptr->valid |= PNG_INFO_sPLT;
+      ++(info_ptr->splt_palettes_num);
+      ++np;
+   }
+   while (++entries, --nentries);
+
+   if (nentries > 0)
+      png_chunk_report(png_ptr, "sPLT out of memory", PNG_CHUNK_WRITE_ERROR);
+}
+#endif /* sPLT */
+
+#ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
+static png_byte
+check_location(png_const_structrp png_ptr, int location)
+{
+   location &= (PNG_HAVE_IHDR|PNG_HAVE_PLTE|PNG_AFTER_IDAT);
 
-      to->nentries = from->nentries;
-      to->depth = from->depth;
+   /* New in 1.6.0; copy the location and check it.  This is an API
+    * change; previously the app had to use the
+    * png_set_unknown_chunk_location API below for each chunk.
+    */
+   if (location == 0 && (png_ptr->mode & PNG_IS_READ_STRUCT) == 0)
+   {
+      /* Write struct, so unknown chunks come from the app */
+      png_app_warning(png_ptr,
+         "png_set_unknown_chunks now expects a valid location");
+      /* Use the old behavior */
+      location = (png_byte)(png_ptr->mode &
+         (PNG_HAVE_IHDR|PNG_HAVE_PLTE|PNG_AFTER_IDAT));
    }
 
-   info_ptr->splt_palettes = np;
-   info_ptr->splt_palettes_num += nentries;
-   info_ptr->valid |= PNG_INFO_sPLT;
-   info_ptr->free_me |= PNG_FREE_SPLT;
+   /* This need not be an internal error - if the app calls
+    * png_set_unknown_chunks on a read pointer it must get the location right.
+    */
+   if (location == 0)
+      png_error(png_ptr, "invalid location in png_set_unknown_chunks");
+
+   /* Now reduce the location to the top-most set bit by removing each least
+    * significant bit in turn.
+    */
+   while (location != (location & -location))
+      location &= ~(location & -location);
+
+   /* The cast is safe because 'location' is a bit mask and only the low four
+    * bits are significant.
+    */
+   return (png_byte)location;
 }
-#endif /* PNG_sPLT_SUPPORTED */
 
-#ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
 void PNGAPI
-png_set_unknown_chunks(png_structp png_ptr,
-   png_infop info_ptr, png_const_unknown_chunkp unknowns, int num_unknowns)
+png_set_unknown_chunks(png_const_structrp png_ptr,
+   png_inforp info_ptr, png_const_unknown_chunkp unknowns, int num_unknowns)
 {
    png_unknown_chunkp np;
-   int i;
 
-   if (png_ptr == NULL || info_ptr == NULL || num_unknowns == 0)
+   if (png_ptr == NULL || info_ptr == NULL || num_unknowns <= 0 ||
+       unknowns == NULL)
       return;
 
-   np = (png_unknown_chunkp)png_malloc_warn(png_ptr,
-       (png_size_t)(info_ptr->unknown_chunks_num + num_unknowns) *
-       png_sizeof(png_unknown_chunk));
+   /* Check for the failure cases where support has been disabled at compile
+    * time.  This code is hardly ever compiled - it's here because
+    * STORE_UNKNOWN_CHUNKS is set by both read and write code (compiling in this
+    * code) but may be meaningless if the read or write handling of unknown
+    * chunks is not compiled in.
+    */
+#  if !defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) && \
+      defined(PNG_READ_SUPPORTED)
+      if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
+      {
+         png_app_error(png_ptr, "no unknown chunk support on read");
+
+         return;
+      }
+#  endif
+#  if !defined(PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED) && \
+      defined(PNG_WRITE_SUPPORTED)
+      if ((png_ptr->mode & PNG_IS_READ_STRUCT) == 0)
+      {
+         png_app_error(png_ptr, "no unknown chunk support on write");
+
+         return;
+      }
+#  endif
+
+   /* Prior to 1.6.0 this code used png_malloc_warn; however, this meant that
+    * unknown critical chunks could be lost with just a warning resulting in
+    * undefined behavior.  Now png_chunk_report is used to provide behavior
+    * appropriate to read or write.
+    */
+   np = png_voidcast(png_unknown_chunkp, png_realloc_array(png_ptr,
+         info_ptr->unknown_chunks, info_ptr->unknown_chunks_num, num_unknowns,
+         sizeof *np));
 
    if (np == NULL)
    {
-      png_warning(png_ptr,
-          "Out of memory while processing unknown chunk");
+      png_chunk_report(png_ptr, "too many unknown chunks",
+         PNG_CHUNK_WRITE_ERROR);
+
       return;
    }
 
-   png_memcpy(np, info_ptr->unknown_chunks,
-       (png_size_t)info_ptr->unknown_chunks_num *
-       png_sizeof(png_unknown_chunk));
-
    png_free(png_ptr, info_ptr->unknown_chunks);
-   info_ptr->unknown_chunks = NULL;
-
-   for (i = 0; i < num_unknowns; i++)
-   {
-      png_unknown_chunkp to = np + info_ptr->unknown_chunks_num + i;
-      png_const_unknown_chunkp from = unknowns + i;
+   info_ptr->unknown_chunks = np; /* safe because it is initialized */
+   info_ptr->free_me |= PNG_FREE_UNKN;
 
-      png_memcpy(to->name, from->name, png_sizeof(from->name));
-      to->name[png_sizeof(to->name)-1] = '\0';
-      to->size = from->size;
+   np += info_ptr->unknown_chunks_num;
 
-      /* Note our location in the read or write sequence */
-      to->location = (png_byte)(png_ptr->mode & 0xff);
+   /* Increment unknown_chunks_num each time round the loop to protect the
+    * just-allocated chunk data.
+    */
+   for (; num_unknowns > 0; --num_unknowns, ++unknowns)
+   {
+      memcpy(np->name, unknowns->name, (sizeof np->name));
+      np->name[(sizeof np->name)-1] = '\0';
+      np->location = check_location(png_ptr, unknowns->location);
 
-      if (from->size == 0)
-         to->data=NULL;
+      if (unknowns->size == 0)
+      {
+         np->data = NULL;
+         np->size = 0;
+      }
 
       else
       {
-         to->data = (png_bytep)png_malloc_warn(png_ptr,
-             (png_size_t)from->size);
+         np->data = png_voidcast(png_bytep,
+            png_malloc_base(png_ptr, unknowns->size));
 
-         if (to->data == NULL)
+         if (np->data == NULL)
          {
-            png_warning(png_ptr,
-                "Out of memory while processing unknown chunk");
-            to->size = 0;
+            png_chunk_report(png_ptr, "unknown chunk: out of memory",
+               PNG_CHUNK_WRITE_ERROR);
+            /* But just skip storing the unknown chunk */
+            continue;
          }
 
-         else
-            png_memcpy(to->data, from->data, from->size);
+         memcpy(np->data, unknowns->data, unknowns->size);
+         np->size = unknowns->size;
       }
-   }
 
-   info_ptr->unknown_chunks = np;
-   info_ptr->unknown_chunks_num += num_unknowns;
-   info_ptr->free_me |= PNG_FREE_UNKN;
+      /* These increments are skipped on out-of-memory for the data - the
+       * unknown chunk entry gets overwritten if the png_chunk_report returns.
+       * This is correct in the read case (the chunk is just dropped.)
+       */
+      ++np;
+      ++(info_ptr->unknown_chunks_num);
+   }
 }
 
 void PNGAPI
-png_set_unknown_chunk_location(png_structp png_ptr, png_infop info_ptr,
+png_set_unknown_chunk_location(png_const_structrp png_ptr, png_inforp info_ptr,
     int chunk, int location)
 {
-   if (png_ptr != NULL && info_ptr != NULL && chunk >= 0 && chunk <
-       info_ptr->unknown_chunks_num)
-      info_ptr->unknown_chunks[chunk].location = (png_byte)location;
-}
-#endif
+   /* This API is pretty pointless in 1.6.0 because the location can be set
+    * before the call to png_set_unknown_chunks.
+    *
+    * TODO: add a png_app_warning in 1.7
+    */
+   if (png_ptr != NULL && info_ptr != NULL && chunk >= 0 &&
+      chunk < info_ptr->unknown_chunks_num)
+   {
+      if ((location & (PNG_HAVE_IHDR|PNG_HAVE_PLTE|PNG_AFTER_IDAT)) == 0)
+      {
+         png_app_error(png_ptr, "invalid unknown chunk location");
+         /* Fake out the pre 1.6.0 behavior: */
+         if ((location & PNG_HAVE_IDAT) != 0) /* undocumented! */
+            location = PNG_AFTER_IDAT;
+
+         else
+            location = PNG_HAVE_IHDR; /* also undocumented */
+      }
 
+      info_ptr->unknown_chunks[chunk].location =
+         check_location(png_ptr, location);
+   }
+}
+#endif /* STORE_UNKNOWN_CHUNKS */
 
 #ifdef PNG_MNG_FEATURES_SUPPORTED
 png_uint_32 PNGAPI
-png_permit_mng_features (png_structp png_ptr, png_uint_32 mng_features)
+png_permit_mng_features (png_structrp png_ptr, png_uint_32 mng_features)
 {
    png_debug(1, "in png_permit_mng_features");
 
    if (png_ptr == NULL)
-      return (png_uint_32)0;
+      return 0;
 
-   png_ptr->mng_features_permitted =
-       (png_byte)(mng_features & PNG_ALL_MNG_FEATURES);
+   png_ptr->mng_features_permitted = mng_features & PNG_ALL_MNG_FEATURES;
 
-   return (png_uint_32)png_ptr->mng_features_permitted;
+   return png_ptr->mng_features_permitted;
 }
 #endif
 
 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+static unsigned int
+add_one_chunk(png_bytep list, unsigned int count, png_const_bytep add, int keep)
+{
+   unsigned int i;
+
+   /* Utility function: update the 'keep' state of a chunk if it is already in
+    * the list, otherwise add it to the list.
+    */
+   for (i=0; i<count; ++i, list += 5)
+   {
+      if (memcmp(list, add, 4) == 0)
+      {
+         list[4] = (png_byte)keep;
+
+         return count;
+      }
+   }
+
+   if (keep != PNG_HANDLE_CHUNK_AS_DEFAULT)
+   {
+      ++count;
+      memcpy(list, add, 4);
+      list[4] = (png_byte)keep;
+   }
+
+   return count;
+}
+
 void PNGAPI
-png_set_keep_unknown_chunks(png_structp png_ptr, int keep, png_const_bytep
-    chunk_list, int num_chunks)
+png_set_keep_unknown_chunks(png_structrp png_ptr, int keep,
+    png_const_bytep chunk_list, int num_chunks_in)
 {
-   png_bytep new_list, p;
-   int i, old_num_chunks;
+   png_bytep new_list;
+   unsigned int num_chunks, old_num_chunks;
+
    if (png_ptr == NULL)
       return;
 
-   if (num_chunks == 0)
+   if (keep < 0 || keep >= PNG_HANDLE_CHUNK_LAST)
    {
-      if (keep == PNG_HANDLE_CHUNK_ALWAYS || keep == PNG_HANDLE_CHUNK_IF_SAFE)
-         png_ptr->flags |= PNG_FLAG_KEEP_UNKNOWN_CHUNKS;
+      png_app_error(png_ptr, "png_set_keep_unknown_chunks: invalid keep");
 
-      else
-         png_ptr->flags &= ~PNG_FLAG_KEEP_UNKNOWN_CHUNKS;
+      return;
+   }
 
-      if (keep == PNG_HANDLE_CHUNK_ALWAYS)
-         png_ptr->flags |= PNG_FLAG_KEEP_UNSAFE_CHUNKS;
+   if (num_chunks_in <= 0)
+   {
+      png_ptr->unknown_default = keep;
 
-      else
-         png_ptr->flags &= ~PNG_FLAG_KEEP_UNSAFE_CHUNKS;
+      /* '0' means just set the flags, so stop here */
+      if (num_chunks_in == 0)
+        return;
+   }
 
-      return;
+   if (num_chunks_in < 0)
+   {
+      /* Ignore all unknown chunks and all chunks recognized by
+       * libpng except for IHDR, PLTE, tRNS, IDAT, and IEND
+       */
+      static PNG_CONST png_byte chunks_to_ignore[] = {
+         98,  75,  71,  68, '\0',  /* bKGD */
+         99,  72,  82,  77, '\0',  /* cHRM */
+        103,  65,  77,  65, '\0',  /* gAMA */
+        104,  73,  83,  84, '\0',  /* hIST */
+        105,  67,  67,  80, '\0',  /* iCCP */
+        105,  84,  88, 116, '\0',  /* iTXt */
+        111,  70,  70, 115, '\0',  /* oFFs */
+        112,  67,  65,  76, '\0',  /* pCAL */
+        112,  72,  89, 115, '\0',  /* pHYs */
+        115,  66,  73,  84, '\0',  /* sBIT */
+        115,  67,  65,  76, '\0',  /* sCAL */
+        115,  80,  76,  84, '\0',  /* sPLT */
+        115,  84,  69,  82, '\0',  /* sTER */
+        115,  82,  71,  66, '\0',  /* sRGB */
+        116,  69,  88, 116, '\0',  /* tEXt */
+        116,  73,  77,  69, '\0',  /* tIME */
+        122,  84,  88, 116, '\0'   /* zTXt */
+      };
+
+      chunk_list = chunks_to_ignore;
+      num_chunks = (unsigned int)/*SAFE*/(sizeof chunks_to_ignore)/5U;
    }
 
-   if (chunk_list == NULL)
-      return;
+   else /* num_chunks_in > 0 */
+   {
+      if (chunk_list == NULL)
+      {
+         /* Prior to 1.6.0 this was silently ignored, now it is an app_error
+          * which can be switched off.
+          */
+         png_app_error(png_ptr, "png_set_keep_unknown_chunks: no chunk list");
+
+         return;
+      }
+
+      num_chunks = num_chunks_in;
+   }
 
    old_num_chunks = png_ptr->num_chunk_list;
-   new_list=(png_bytep)png_malloc(png_ptr,
-       (png_size_t)(5*(num_chunks + old_num_chunks)));
+   if (png_ptr->chunk_list == NULL)
+      old_num_chunks = 0;
+
+   /* Since num_chunks is always restricted to UINT_MAX/5 this can't overflow.
+    */
+   if (num_chunks + old_num_chunks > UINT_MAX/5)
+   {
+      png_app_error(png_ptr, "png_set_keep_unknown_chunks: too many chunks");
+
+      return;
+   }
 
-   if (png_ptr->chunk_list != NULL)
+   /* If these chunks are being reset to the default then no more memory is
+    * required because add_one_chunk above doesn't extend the list if the 'keep'
+    * parameter is the default.
+    */
+   if (keep != 0)
    {
-      png_memcpy(new_list, png_ptr->chunk_list,
-          (png_size_t)(5*old_num_chunks));
-      png_free(png_ptr, png_ptr->chunk_list);
-      png_ptr->chunk_list=NULL;
+      new_list = png_voidcast(png_bytep, png_malloc(png_ptr,
+          5 * (num_chunks + old_num_chunks)));
+
+      if (old_num_chunks > 0)
+         memcpy(new_list, png_ptr->chunk_list, 5*old_num_chunks);
    }
 
-   png_memcpy(new_list + 5*old_num_chunks, chunk_list,
-       (png_size_t)(5*num_chunks));
+   else if (old_num_chunks > 0)
+      new_list = png_ptr->chunk_list;
+
+   else
+      new_list = NULL;
+
+   /* Add the new chunks together with each one's handling code.  If the chunk
+    * already exists the code is updated, otherwise the chunk is added to the
+    * end.  (In libpng 1.6.0 order no longer matters because this code enforces
+    * the earlier convention that the last setting is the one that is used.)
+    */
+   if (new_list != NULL)
+   {
+      png_const_bytep inlist;
+      png_bytep outlist;
+      unsigned int i;
+
+      for (i=0; i<num_chunks; ++i)
+      {
+         old_num_chunks = add_one_chunk(new_list, old_num_chunks,
+            chunk_list+5*i, keep);
+      }
 
-   for (p = new_list + 5*old_num_chunks + 4, i = 0; i<num_chunks; i++, p += 5)
-      *p=(png_byte)keep;
+      /* Now remove any spurious 'default' entries. */
+      num_chunks = 0;
+      for (i=0, inlist=outlist=new_list; i<old_num_chunks; ++i, inlist += 5)
+      {
+         if (inlist[4])
+         {
+            if (outlist != inlist)
+               memcpy(outlist, inlist, 5);
+            outlist += 5;
+            ++num_chunks;
+         }
+      }
+
+      /* This means the application has removed all the specialized handling. */
+      if (num_chunks == 0)
+      {
+         if (png_ptr->chunk_list != new_list)
+            png_free(png_ptr, new_list);
+
+         new_list = NULL;
+      }
+   }
+
+   else
+      num_chunks = 0;
+
+   png_ptr->num_chunk_list = num_chunks;
+
+   if (png_ptr->chunk_list != new_list)
+   {
+      if (png_ptr->chunk_list != NULL)
+         png_free(png_ptr, png_ptr->chunk_list);
 
-   png_ptr->num_chunk_list = old_num_chunks + num_chunks;
-   png_ptr->chunk_list = new_list;
-   png_ptr->free_me |= PNG_FREE_LIST;
+      png_ptr->chunk_list = new_list;
+   }
 }
 #endif
 
 #ifdef PNG_READ_USER_CHUNKS_SUPPORTED
 void PNGAPI
-png_set_read_user_chunk_fn(png_structp png_ptr, png_voidp user_chunk_ptr,
+png_set_read_user_chunk_fn(png_structrp png_ptr, png_voidp user_chunk_ptr,
     png_user_chunk_ptr read_user_chunk_fn)
 {
    png_debug(1, "in png_set_read_user_chunk_fn");
@@ -1186,64 +1474,94 @@ png_set_read_user_chunk_fn(png_structp png_ptr, png_voidp user_chunk_ptr,
 
 #ifdef PNG_INFO_IMAGE_SUPPORTED
 void PNGAPI
-png_set_rows(png_structp png_ptr, png_infop info_ptr, png_bytepp row_pointers)
+png_set_rows(png_const_structrp png_ptr, png_inforp info_ptr,
+    png_bytepp row_pointers)
 {
    png_debug1(1, "in %s storage function", "rows");
 
    if (png_ptr == NULL || info_ptr == NULL)
       return;
 
-   if (info_ptr->row_pointers && (info_ptr->row_pointers != row_pointers))
+   if (info_ptr->row_pointers != NULL &&
+       (info_ptr->row_pointers != row_pointers))
       png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0);
 
    info_ptr->row_pointers = row_pointers;
 
-   if (row_pointers)
+   if (row_pointers != NULL)
       info_ptr->valid |= PNG_INFO_IDAT;
 }
 #endif
 
 void PNGAPI
-png_set_compression_buffer_size(png_structp png_ptr, png_size_t size)
+png_set_compression_buffer_size(png_structrp png_ptr, png_size_t size)
 {
     if (png_ptr == NULL)
        return;
 
-    png_free(png_ptr, png_ptr->zbuf);
+    if (size == 0 || size > PNG_UINT_31_MAX)
+       png_error(png_ptr, "invalid compression buffer size");
 
-    if (size > ZLIB_IO_MAX)
-    {
-       png_warning(png_ptr, "Attempt to set buffer size beyond max ignored");
-       png_ptr->zbuf_size = ZLIB_IO_MAX;
-       size = ZLIB_IO_MAX; /* must fit */
-    }
+#  ifdef PNG_SEQUENTIAL_READ_SUPPORTED
+      if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
+      {
+         png_ptr->IDAT_read_size = (png_uint_32)size; /* checked above */
+         return;
+      }
+#  endif
 
-    else
-       png_ptr->zbuf_size = (uInt)size;
+#  ifdef PNG_WRITE_SUPPORTED
+      if ((png_ptr->mode & PNG_IS_READ_STRUCT) == 0)
+      {
+         if (png_ptr->zowner != 0)
+         {
+            png_warning(png_ptr,
+              "Compression buffer size cannot be changed because it is in use");
 
-    png_ptr->zbuf = (png_bytep)png_malloc(png_ptr, size);
+            return;
+         }
 
-    /* The following ensures a relatively safe failure if this gets called while
-     * the buffer is actually in use.
-     */
-    png_ptr->zstream.next_out = png_ptr->zbuf;
-    png_ptr->zstream.avail_out = 0;
-    png_ptr->zstream.avail_in = 0;
+#ifndef __COVERITY__
+         if (size > ZLIB_IO_MAX)
+         {
+            png_warning(png_ptr,
+               "Compression buffer size limited to system maximum");
+            size = ZLIB_IO_MAX; /* must fit */
+         }
+#endif
+
+         if (size < 6)
+         {
+            /* Deflate will potentially go into an infinite loop on a SYNC_FLUSH
+             * if this is permitted.
+             */
+            png_warning(png_ptr,
+               "Compression buffer size cannot be reduced below 6");
+
+            return;
+         }
+
+         if (png_ptr->zbuffer_size != size)
+         {
+            png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list);
+            png_ptr->zbuffer_size = (uInt)size;
+         }
+      }
+#  endif
 }
 
 void PNGAPI
-png_set_invalid(png_structp png_ptr, png_infop info_ptr, int mask)
+png_set_invalid(png_const_structrp png_ptr, png_inforp info_ptr, int mask)
 {
-   if (png_ptr && info_ptr)
+   if (png_ptr != NULL && info_ptr != NULL)
       info_ptr->valid &= ~mask;
 }
 
 
-
 #ifdef PNG_SET_USER_LIMITS_SUPPORTED
 /* This function was added to libpng 1.2.6 */
 void PNGAPI
-png_set_user_limits (png_structp png_ptr, png_uint_32 user_width_max,
+png_set_user_limits (png_structrp png_ptr, png_uint_32 user_width_max,
     png_uint_32 user_height_max)
 {
    /* Images with dimensions larger than these limits will be
@@ -1259,51 +1577,64 @@ png_set_user_limits (png_structp png_ptr, png_uint_32 user_width_max,
 
 /* This function was added to libpng 1.4.0 */
 void PNGAPI
-png_set_chunk_cache_max (png_structp png_ptr,
-   png_uint_32 user_chunk_cache_max)
+png_set_chunk_cache_max (png_structrp png_ptr, png_uint_32 user_chunk_cache_max)
 {
-    if (png_ptr)
-       png_ptr->user_chunk_cache_max = user_chunk_cache_max;
+   if (png_ptr != NULL)
+      png_ptr->user_chunk_cache_max = user_chunk_cache_max;
 }
 
 /* This function was added to libpng 1.4.1 */
 void PNGAPI
-png_set_chunk_malloc_max (png_structp png_ptr,
+png_set_chunk_malloc_max (png_structrp png_ptr,
     png_alloc_size_t user_chunk_malloc_max)
 {
-   if (png_ptr)
+   if (png_ptr != NULL)
       png_ptr->user_chunk_malloc_max = user_chunk_malloc_max;
 }
-#endif /* ?PNG_SET_USER_LIMITS_SUPPORTED */
+#endif /* ?SET_USER_LIMITS */
 
 
 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
 void PNGAPI
-png_set_benign_errors(png_structp png_ptr, int allowed)
+png_set_benign_errors(png_structrp png_ptr, int allowed)
 {
    png_debug(1, "in png_set_benign_errors");
 
-   if (allowed)
-      png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN;
+   /* If allowed is 1, png_benign_error() is treated as a warning.
+    *
+    * If allowed is 0, png_benign_error() is treated as an error (which
+    * is the default behavior if png_set_benign_errors() is not called).
+    */
+
+   if (allowed != 0)
+      png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN |
+         PNG_FLAG_APP_WARNINGS_WARN | PNG_FLAG_APP_ERRORS_WARN;
 
    else
-      png_ptr->flags &= ~PNG_FLAG_BENIGN_ERRORS_WARN;
+      png_ptr->flags &= ~(PNG_FLAG_BENIGN_ERRORS_WARN |
+         PNG_FLAG_APP_WARNINGS_WARN | PNG_FLAG_APP_ERRORS_WARN);
 }
-#endif /* PNG_BENIGN_ERRORS_SUPPORTED */
-
-#ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
-   /* Do not report invalid palette index; added at libng-1.5.10 */
+#endif /* BENIGN_ERRORS */
+
+#ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
+   /* Whether to report invalid palette index; added at libng-1.5.10.
+    * It is possible for an indexed (color-type==3) PNG file to contain
+    * pixels with invalid (out-of-range) indexes if the PLTE chunk has
+    * fewer entries than the image's bit-depth would allow. We recover
+    * from this gracefully by filling any incomplete palette with zeros
+    * (opaque black).  By default, when this occurs libpng will issue
+    * a benign error.  This API can be used to override that behavior.
+    */
 void PNGAPI
-png_set_check_for_invalid_index(png_structp png_ptr, int allowed)
+png_set_check_for_invalid_index(png_structrp png_ptr, int allowed)
 {
    png_debug(1, "in png_set_check_for_invalid_index");
 
-   if (allowed)
+   if (allowed > 0)
       png_ptr->num_palette_max = 0;
 
    else
       png_ptr->num_palette_max = -1;
 }
 #endif
-
-#endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */
+#endif /* READ || WRITE */
diff --git a/src/3rdparty/libpng/pngstruct.h b/src/3rdparty/libpng/pngstruct.h
index 43a45cd..8420d09 100644
--- a/src/3rdparty/libpng/pngstruct.h
+++ b/src/3rdparty/libpng/pngstruct.h
@@ -1,12 +1,11 @@
 
 /* pngstruct.h - header file for PNG reference library
  *
- * Copyright (c) 1998-2011 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.1 [March 28, 2013]
+ * Copyright (c) 1998-2013 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
- * Last changed in libpng 1.5.9 [March 29, 2012]
- *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
  * and license in png.h
@@ -24,13 +23,130 @@
  * in this structure and is required for decompressing the LZ compressed
  * data in PNG files.
  */
+#ifndef ZLIB_CONST
+   /* We must ensure that zlib uses 'const' in declarations. */
+#  define ZLIB_CONST
+#endif
 #include "zlib.h"
+#ifdef const
+   /* zlib.h sometimes #defines const to nothing, undo this. */
+#  undef const
+#endif
+
+/* zlib.h has mediocre z_const use before 1.2.6, this stuff is for compatibility
+ * with older builds.
+ */
+#if ZLIB_VERNUM < 0x1260
+#  define PNGZ_MSG_CAST(s) png_constcast(char*,s)
+#  define PNGZ_INPUT_CAST(b) png_constcast(png_bytep,b)
+#else
+#  define PNGZ_MSG_CAST(s) (s)
+#  define PNGZ_INPUT_CAST(b) (b)
+#endif
+
+/* zlib.h declares a magic type 'uInt' that limits the amount of data that zlib
+ * can handle at once.  This type need be no larger than 16 bits (so maximum of
+ * 65535), this define allows us to discover how big it is, but limited by the
+ * maximuum for png_size_t.  The value can be overriden in a library build
+ * (pngusr.h, or set it in CPPFLAGS) and it works to set it to a considerably
+ * lower value (e.g. 255 works).  A lower value may help memory usage (slightly)
+ * and may even improve performance on some systems (and degrade it on others.)
+ */
+#ifndef ZLIB_IO_MAX
+#  define ZLIB_IO_MAX ((uInt)-1)
+#endif
+
+#ifdef PNG_WRITE_SUPPORTED
+/* The type of a compression buffer list used by the write code. */
+typedef struct png_compression_buffer
+{
+   struct png_compression_buffer *next;
+   png_byte                       output[1]; /* actually zbuf_size */
+} png_compression_buffer, *png_compression_bufferp;
+
+#define PNG_COMPRESSION_BUFFER_SIZE(pp)\
+   (offsetof(png_compression_buffer, output) + (pp)->zbuffer_size)
+#endif
+
+/* Colorspace support; structures used in png_struct, png_info and in internal
+ * functions to hold and communicate information about the color space.
+ *
+ * PNG_COLORSPACE_SUPPORTED is only required if the application will perform
+ * colorspace corrections, otherwise all the colorspace information can be
+ * skipped and the size of libpng can be reduced (significantly) by compiling
+ * out the colorspace support.
+ */
+#ifdef PNG_COLORSPACE_SUPPORTED
+/* The chromaticities of the red, green and blue colorants and the chromaticity
+ * of the corresponding white point (i.e. of rgb(1.0,1.0,1.0)).
+ */
+typedef struct png_xy
+{
+   png_fixed_point redx, redy;
+   png_fixed_point greenx, greeny;
+   png_fixed_point bluex, bluey;
+   png_fixed_point whitex, whitey;
+} png_xy;
+
+/* The same data as above but encoded as CIE XYZ values.  When this data comes
+ * from chromaticities the sum of the Y values is assumed to be 1.0
+ */
+typedef struct png_XYZ
+{
+   png_fixed_point red_X, red_Y, red_Z;
+   png_fixed_point green_X, green_Y, green_Z;
+   png_fixed_point blue_X, blue_Y, blue_Z;
+} png_XYZ;
+#endif /* COLORSPACE */
+
+#if defined(PNG_COLORSPACE_SUPPORTED) || defined(PNG_GAMMA_SUPPORTED)
+/* A colorspace is all the above plus, potentially, profile information;
+ * however at present libpng does not use the profile internally so it is only
+ * stored in the png_info struct (if iCCP is supported.)  The rendering intent
+ * is retained here and is checked.
+ *
+ * The file gamma encoding information is also stored here and gamma correction
+ * is done by libpng, whereas color correction must currently be done by the
+ * application.
+ */
+typedef struct png_colorspace
+{
+#ifdef PNG_GAMMA_SUPPORTED
+   png_fixed_point gamma;        /* File gamma */
+#endif
+
+#ifdef PNG_COLORSPACE_SUPPORTED
+   png_xy      end_points_xy;    /* End points as chromaticities */
+   png_XYZ     end_points_XYZ;   /* End points as CIE XYZ colorant values */
+   png_uint_16 rendering_intent; /* Rendering intent of a profile */
+#endif
+
+   /* Flags are always defined to simplify the code. */
+   png_uint_16 flags;            /* As defined below */
+} png_colorspace, * PNG_RESTRICT png_colorspacerp;
+
+typedef const png_colorspace * PNG_RESTRICT png_const_colorspacerp;
+
+/* General flags for the 'flags' field */
+#define PNG_COLORSPACE_HAVE_GAMMA           0x0001
+#define PNG_COLORSPACE_HAVE_ENDPOINTS       0x0002
+#define PNG_COLORSPACE_HAVE_INTENT          0x0004
+#define PNG_COLORSPACE_FROM_gAMA            0x0008
+#define PNG_COLORSPACE_FROM_cHRM            0x0010
+#define PNG_COLORSPACE_FROM_sRGB            0x0020
+#define PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB 0x0040
+#define PNG_COLORSPACE_MATCHES_sRGB         0x0080 /* exact match on profile */
+#define PNG_COLORSPACE_INVALID              0x8000
+#define PNG_COLORSPACE_CANCEL(flags)        (0xffff ^ (flags))
+#endif /* COLORSPACE || GAMMA */
 
 struct png_struct_def
 {
 #ifdef PNG_SETJMP_SUPPORTED
-   jmp_buf longjmp_buffer;    /* used in png_error */
+   jmp_buf jmp_buf_local;     /* New name in 1.6.0 for jmp_buf in png_struct */
    png_longjmp_ptr longjmp_fn;/* setjmp non-local goto function. */
+   jmp_buf *jmp_buf_ptr;      /* passed to longjmp_fn */
+   size_t jmp_buf_size;       /* size of the above, if allocated */
 #endif
    png_error_ptr error_fn;    /* function for printing errors and aborting */
 #ifdef PNG_WARNINGS_SUPPORTED
@@ -63,22 +179,12 @@ struct png_struct_def
    png_uint_32 flags;         /* flags indicating various things to libpng */
    png_uint_32 transformations; /* which transformations to perform */
 
-   z_stream zstream;          /* pointer to decompression structure (below) */
-   png_bytep zbuf;            /* buffer for zlib */
-   uInt zbuf_size;            /* size of zbuf (typically 65536) */
-#ifdef PNG_WRITE_SUPPORTED
+   png_uint_32 zowner;        /* ID (chunk type) of zstream owner, 0 if none */
+   z_stream    zstream;       /* decompression structure */
 
-/* Added in 1.5.4: state to keep track of whether the zstream has been
- * initialized and if so whether it is for IDAT or some other chunk.
- */
-#define PNG_ZLIB_UNINITIALIZED 0
-#define PNG_ZLIB_FOR_IDAT      1
-#define PNG_ZLIB_FOR_TEXT      2 /* anything other than IDAT */
-#define PNG_ZLIB_USE_MASK      3 /* bottom two bits */
-#define PNG_ZLIB_IN_USE        4 /* a flag value */
-
-   png_uint_32 zlib_state;       /* State of zlib initialization */
-/* End of material added at libpng 1.5.4 */
+#ifdef PNG_WRITE_SUPPORTED
+   png_compression_bufferp zbuffer_list; /* Created on demand during write */
+   uInt                    zbuffer_size; /* size of the actual buffer */
 
    int zlib_level;            /* holds zlib compression level */
    int zlib_method;           /* holds zlib compression method */
@@ -87,8 +193,7 @@ struct png_struct_def
    int zlib_strategy;         /* holds zlib compression strategy */
 #endif
 /* Added at libpng 1.5.4 */
-#if defined(PNG_WRITE_COMPRESSED_TEXT_SUPPORTED) || \
-    defined(PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED)
+#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
    int zlib_text_level;            /* holds zlib compression level */
    int zlib_text_method;           /* holds zlib compression method */
    int zlib_text_window_bits;      /* holds zlib compression window bits */
@@ -96,6 +201,14 @@ struct png_struct_def
    int zlib_text_strategy;         /* holds zlib compression strategy */
 #endif
 /* End of material added at libpng 1.5.4 */
+/* Added at libpng 1.6.0 */
+#ifdef PNG_WRITE_SUPPORTED
+   int zlib_set_level;        /* Actual values set into the zstream on write */
+   int zlib_set_method;
+   int zlib_set_window_bits;
+   int zlib_set_mem_level;
+   int zlib_set_strategy;
+#endif
 
    png_uint_32 width;         /* width of image in pixels */
    png_uint_32 height;        /* height of image in pixels */
@@ -111,10 +224,12 @@ struct png_struct_def
    png_bytep row_buf;         /* buffer to save current (unfiltered) row.
                                * This is a pointer into big_row_buf
                                */
+#ifdef PNG_WRITE_SUPPORTED
    png_bytep sub_row;         /* buffer to save "sub" row when filtering */
    png_bytep up_row;          /* buffer to save "up" row when filtering */
    png_bytep avg_row;         /* buffer to save "avg" row when filtering */
    png_bytep paeth_row;       /* buffer to save "Paeth" row when filtering */
+#endif
    png_size_t info_rowbytes;  /* Added in 1.5.4: cache of updated row bytes */
 
    png_uint_32 idat_size;     /* current IDAT size for read */
@@ -138,15 +253,14 @@ struct png_struct_def
    png_byte usr_bit_depth;    /* bit depth of users row: write only */
    png_byte pixel_depth;      /* number of bits per pixel */
    png_byte channels;         /* number of channels in file */
+#ifdef PNG_WRITE_SUPPORTED
    png_byte usr_channels;     /* channels at start of write: write only */
+#endif
    png_byte sig_bytes;        /* magic bytes read/written from start of file */
    png_byte maximum_pixel_depth;
                               /* pixel depth used for the row buffers */
    png_byte transformed_pixel_depth;
                               /* pixel depth after read/write transforms */
-   png_byte io_chunk_string[5];
-                              /* string name of chunk */
-
 #if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
    png_uint_16 filler;           /* filler bytes for pixel expansion */
 #endif
@@ -159,7 +273,7 @@ struct png_struct_def
 #ifdef PNG_READ_GAMMA_SUPPORTED
    png_color_16 background_1; /* background normalized to gamma 1.0 */
 #endif
-#endif /* PNG_bKGD_SUPPORTED */
+#endif /* bKGD */
 
 #ifdef PNG_WRITE_FLUSH_SUPPORTED
    png_flush_ptr output_flush_fn; /* Function for flushing output */
@@ -169,7 +283,6 @@ struct png_struct_def
 
 #ifdef PNG_READ_GAMMA_SUPPORTED
    int gamma_shift;      /* number of "insignificant" bits in 16-bit gamma */
-   png_fixed_point gamma;        /* file gamma value */
    png_fixed_point screen_gamma; /* screen gamma value (display_exponent) */
 
    png_bytep gamma_table;     /* gamma table for 8-bit depth files */
@@ -217,7 +330,7 @@ struct png_struct_def
    int process_mode;                 /* what push library is currently doing */
    int cur_palette;                  /* current push library palette index */
 
-#endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
+#endif /* PROGRESSIVE_READ */
 
 #if defined(__TURBOC__) && !defined(_Windows) && !defined(__FLAT__)
 /* For the Borland special 64K segment handler */
@@ -233,10 +346,6 @@ struct png_struct_def
    png_bytep quantize_index; /* index translation for palette files */
 #endif
 
-#if defined(PNG_READ_QUANTIZE_SUPPORTED) || defined(PNG_hIST_SUPPORTED)
-   png_uint_16p hist;                /* histogram */
-#endif
-
 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
    png_byte heuristic_method;        /* heuristic for row filter selection */
    png_byte num_prev_filters;        /* number of weights for previous rows */
@@ -247,9 +356,17 @@ struct png_struct_def
    png_uint_16p inv_filter_costs;    /* 1/relative filter calculation cost */
 #endif
 
+   /* Options */
+#ifdef PNG_SET_OPTION_SUPPORTED
+   png_byte options;           /* On/off state (up to 4 options) */
+#endif
+
+#if PNG_LIBPNG_VER < 10700
+/* To do: remove this from libpng-1.7 */
 #ifdef PNG_TIME_RFC1123_SUPPORTED
    char time_buffer[29]; /* String to hold RFC 1123 time text */
 #endif
+#endif
 
 /* New members added in libpng-1.0.6 */
 
@@ -257,17 +374,16 @@ struct png_struct_def
 
 #ifdef PNG_USER_CHUNKS_SUPPORTED
    png_voidp user_chunk_ptr;
+#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
    png_user_chunk_ptr read_user_chunk_fn; /* user read chunk handler */
 #endif
-
-#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
-   int num_chunk_list;
-   png_bytep chunk_list;
 #endif
 
-#ifdef PNG_READ_sRGB_SUPPORTED
-   /* Added in 1.5.5 to record an sRGB chunk in the png. */
-   png_byte is_sRGB;
+#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
+   int          unknown_default; /* As PNG_HANDLE_* */
+   unsigned int num_chunk_list;  /* Number of entries in the list */
+   png_bytep    chunk_list;      /* List of png_byte[5]; the textual chunk name
+                                  * followed by a PNG_HANDLE_* byte */
 #endif
 
 /* New members added in libpng-1.0.3 */
@@ -332,16 +448,24 @@ struct png_struct_def
 #endif
 
 /* New member added in libpng-1.0.25 and 1.2.17 */
-#ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
-   /* Storage for unknown chunk that the library doesn't recognize. */
+#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
+   /* Temporary storage for unknown chunk that the library doesn't recognize,
+    * used while reading the chunk.
+    */
    png_unknown_chunk unknown_chunk;
 #endif
 
 /* New member added in libpng-1.2.26 */
   png_size_t old_big_row_buf_size;
 
+#ifdef PNG_READ_SUPPORTED
 /* New member added in libpng-1.2.30 */
-  png_charp chunkdata;  /* buffer for reading chunk data */
+  png_bytep        read_buffer;      /* buffer for reading chunk data */
+  png_alloc_size_t read_buffer_size; /* current size of the buffer */
+#endif
+#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
+  uInt             IDAT_read_size;   /* limit on read buffer size for IDAT */
+#endif
 
 #ifdef PNG_IO_STATE_SUPPORTED
 /* New member added in libpng-1.4.0 */
@@ -351,7 +475,14 @@ struct png_struct_def
 /* New member added in libpng-1.5.6 */
    png_bytep big_prev_row;
 
+/* New member added in libpng-1.5.7 */
    void (*read_filter[PNG_FILTER_VALUE_LAST-1])(png_row_infop row_info,
       png_bytep row, png_const_bytep prev_row);
+
+#ifdef PNG_READ_SUPPORTED
+#if defined(PNG_COLORSPACE_SUPPORTED) || defined(PNG_GAMMA_SUPPORTED)
+   png_colorspace   colorspace;
+#endif
+#endif
 };
 #endif /* PNGSTRUCT_H */
diff --git a/src/3rdparty/libpng/pngtrans.c b/src/3rdparty/libpng/pngtrans.c
index fef12f1..cd3a79b 100644
--- a/src/3rdparty/libpng/pngtrans.c
+++ b/src/3rdparty/libpng/pngtrans.c
@@ -1,8 +1,8 @@
 
 /* pngtrans.c - transforms the data in a row (used by both readers and writers)
  *
- * Last changed in libpng 1.5.10 [March 8, 2012]
- * Copyright (c) 1998-2012 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.17 [March 26, 2015]
+ * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
@@ -18,7 +18,7 @@
 #if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
 /* Turn on BGR-to-RGB mapping */
 void PNGAPI
-png_set_bgr(png_structp png_ptr)
+png_set_bgr(png_structrp png_ptr)
 {
    png_debug(1, "in png_set_bgr");
 
@@ -32,7 +32,7 @@ png_set_bgr(png_structp png_ptr)
 #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
 /* Turn on 16 bit byte swapping */
 void PNGAPI
-png_set_swap(png_structp png_ptr)
+png_set_swap(png_structrp png_ptr)
 {
    png_debug(1, "in png_set_swap");
 
@@ -47,7 +47,7 @@ png_set_swap(png_structp png_ptr)
 #if defined(PNG_READ_PACK_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED)
 /* Turn on pixel packing */
 void PNGAPI
-png_set_packing(png_structp png_ptr)
+png_set_packing(png_structrp png_ptr)
 {
    png_debug(1, "in png_set_packing");
 
@@ -57,7 +57,9 @@ png_set_packing(png_structp png_ptr)
    if (png_ptr->bit_depth < 8)
    {
       png_ptr->transformations |= PNG_PACK;
-      png_ptr->usr_bit_depth = 8;
+#     ifdef PNG_WRITE_SUPPORTED
+         png_ptr->usr_bit_depth = 8;
+#     endif
    }
 }
 #endif
@@ -65,7 +67,7 @@ png_set_packing(png_structp png_ptr)
 #if defined(PNG_READ_PACKSWAP_SUPPORTED)||defined(PNG_WRITE_PACKSWAP_SUPPORTED)
 /* Turn on packed pixel swapping */
 void PNGAPI
-png_set_packswap(png_structp png_ptr)
+png_set_packswap(png_structrp png_ptr)
 {
    png_debug(1, "in png_set_packswap");
 
@@ -79,7 +81,7 @@ png_set_packswap(png_structp png_ptr)
 
 #if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)
 void PNGAPI
-png_set_shift(png_structp png_ptr, png_const_color_8p true_bits)
+png_set_shift(png_structrp png_ptr, png_const_color_8p true_bits)
 {
    png_debug(1, "in png_set_shift");
 
@@ -94,11 +96,11 @@ png_set_shift(png_structp png_ptr, png_const_color_8p true_bits)
 #if defined(PNG_READ_INTERLACING_SUPPORTED) || \
     defined(PNG_WRITE_INTERLACING_SUPPORTED)
 int PNGAPI
-png_set_interlace_handling(png_structp png_ptr)
+png_set_interlace_handling(png_structrp png_ptr)
 {
    png_debug(1, "in png_set_interlace handling");
 
-   if (png_ptr && png_ptr->interlaced)
+   if (png_ptr != 0 && png_ptr->interlaced != 0)
    {
       png_ptr->transformations |= PNG_INTERLACE;
       return (7);
@@ -115,44 +117,91 @@ png_set_interlace_handling(png_structp png_ptr)
  * that don't like bytes as parameters.
  */
 void PNGAPI
-png_set_filler(png_structp png_ptr, png_uint_32 filler, int filler_loc)
+png_set_filler(png_structrp png_ptr, png_uint_32 filler, int filler_loc)
 {
    png_debug(1, "in png_set_filler");
 
    if (png_ptr == NULL)
       return;
 
+   /* In libpng 1.6 it is possible to determine whether this is a read or write
+    * operation and therefore to do more checking here for a valid call.
+    */
+   if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
+   {
+#     ifdef PNG_READ_FILLER_SUPPORTED
+         /* On read png_set_filler is always valid, regardless of the base PNG
+          * format, because other transformations can give a format where the
+          * filler code can execute (basically an 8 or 16-bit component RGB or G
+          * format.)
+          *
+          * NOTE: usr_channels is not used by the read code!  (This has led to
+          * confusion in the past.)  The filler is only used in the read code.
+          */
+         png_ptr->filler = (png_uint_16)filler;
+#     else
+         png_app_error(png_ptr, "png_set_filler not supported on read");
+         PNG_UNUSED(filler) /* not used in the write case */
+         return;
+#     endif
+   }
+
+   else /* write */
+   {
+#     ifdef PNG_WRITE_FILLER_SUPPORTED
+         /* On write the usr_channels parameter must be set correctly at the
+          * start to record the number of channels in the app-supplied data.
+          */
+         switch (png_ptr->color_type)
+         {
+            case PNG_COLOR_TYPE_RGB:
+               png_ptr->usr_channels = 4;
+               break;
+
+            case PNG_COLOR_TYPE_GRAY:
+               if (png_ptr->bit_depth >= 8)
+               {
+                  png_ptr->usr_channels = 2;
+                  break;
+               }
+
+               else
+               {
+                  /* There simply isn't any code in libpng to strip out bits
+                   * from bytes when the components are less than a byte in
+                   * size!
+                   */
+                  png_app_error(png_ptr,
+                     "png_set_filler is invalid for low bit depth gray output");
+                  return;
+               }
+
+            default:
+               png_app_error(png_ptr,
+                  "png_set_filler: inappropriate color type");
+               return;
+         }
+#     else
+         png_app_error(png_ptr, "png_set_filler not supported on write");
+         return;
+#     endif
+   }
+
+   /* Here on success - libpng supports the operation, set the transformation
+    * and the flag to say where the filler channel is.
+    */
    png_ptr->transformations |= PNG_FILLER;
-   png_ptr->filler = (png_uint_16)filler;
 
    if (filler_loc == PNG_FILLER_AFTER)
       png_ptr->flags |= PNG_FLAG_FILLER_AFTER;
 
    else
       png_ptr->flags &= ~PNG_FLAG_FILLER_AFTER;
-
-   /* This should probably go in the "do_read_filler" routine.
-    * I attempted to do that in libpng-1.0.1a but that caused problems
-    * so I restored it in libpng-1.0.2a
-   */
-
-   if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
-   {
-      png_ptr->usr_channels = 4;
-   }
-
-   /* Also I added this in libpng-1.0.2a (what happens when we expand
-    * a less-than-8-bit grayscale to GA?) */
-
-   if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY && png_ptr->bit_depth >= 8)
-   {
-      png_ptr->usr_channels = 2;
-   }
 }
 
 /* Added to libpng-1.2.7 */
 void PNGAPI
-png_set_add_alpha(png_structp png_ptr, png_uint_32 filler, int filler_loc)
+png_set_add_alpha(png_structrp png_ptr, png_uint_32 filler, int filler_loc)
 {
    png_debug(1, "in png_set_add_alpha");
 
@@ -160,7 +209,9 @@ png_set_add_alpha(png_structp png_ptr, png_uint_32 filler, int filler_loc)
       return;
 
    png_set_filler(png_ptr, filler, filler_loc);
-   png_ptr->transformations |= PNG_ADD_ALPHA;
+   /* The above may fail to do anything. */
+   if ((png_ptr->transformations & PNG_FILLER) != 0)
+      png_ptr->transformations |= PNG_ADD_ALPHA;
 }
 
 #endif
@@ -168,7 +219,7 @@ png_set_add_alpha(png_structp png_ptr, png_uint_32 filler, int filler_loc)
 #if defined(PNG_READ_SWAP_ALPHA_SUPPORTED) || \
     defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
 void PNGAPI
-png_set_swap_alpha(png_structp png_ptr)
+png_set_swap_alpha(png_structrp png_ptr)
 {
    png_debug(1, "in png_set_swap_alpha");
 
@@ -182,7 +233,7 @@ png_set_swap_alpha(png_structp png_ptr)
 #if defined(PNG_READ_INVERT_ALPHA_SUPPORTED) || \
     defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
 void PNGAPI
-png_set_invert_alpha(png_structp png_ptr)
+png_set_invert_alpha(png_structrp png_ptr)
 {
    png_debug(1, "in png_set_invert_alpha");
 
@@ -195,7 +246,7 @@ png_set_invert_alpha(png_structp png_ptr)
 
 #if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
 void PNGAPI
-png_set_invert_mono(png_structp png_ptr)
+png_set_invert_mono(png_structrp png_ptr)
 {
    png_debug(1, "in png_set_invert_mono");
 
@@ -276,9 +327,16 @@ png_do_swap(png_row_infop row_info, png_bytep row)
 
       for (i = 0; i < istop; i++, rp += 2)
       {
+#ifdef PNG_BUILTIN_BSWAP16_SUPPORTED
+         /* Feature added to libpng-1.6.11 for testing purposes, not
+          * enabled by default.
+          */
+         *(png_uint_16*)rp = __builtin_bswap16(*(png_uint_16*)rp);
+#else
          png_byte t = *rp;
          *rp = *(rp + 1);
          *(rp + 1) = t;
+#endif
       }
    }
 }
@@ -420,7 +478,7 @@ png_do_packswap(png_row_infop row_info, png_bytep row)
          *rp = table[*rp];
    }
 }
-#endif /* PNG_READ_PACKSWAP_SUPPORTED or PNG_WRITE_PACKSWAP_SUPPORTED */
+#endif /* PACKSWAP || WRITE_PACKSWAP */
 
 #if defined(PNG_WRITE_FILLER_SUPPORTED) || \
     defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
@@ -452,7 +510,7 @@ png_do_strip_channel(png_row_infop row_info, png_bytep row, int at_start)
    {
       if (row_info->bit_depth == 8)
       {
-         if (at_start) /* Skip initial filler */
+         if (at_start != 0) /* Skip initial filler */
             ++sp;
          else          /* Skip initial channel and, for sp, the filler */
             sp += 2, ++dp;
@@ -466,7 +524,7 @@ png_do_strip_channel(png_row_infop row_info, png_bytep row, int at_start)
 
       else if (row_info->bit_depth == 16)
       {
-         if (at_start) /* Skip initial filler */
+         if (at_start != 0) /* Skip initial filler */
             sp += 2;
          else          /* Skip initial channel and, for sp, the filler */
             sp += 4, dp += 2;
@@ -492,7 +550,7 @@ png_do_strip_channel(png_row_infop row_info, png_bytep row, int at_start)
    {
       if (row_info->bit_depth == 8)
       {
-         if (at_start) /* Skip initial filler */
+         if (at_start != 0) /* Skip initial filler */
             ++sp;
          else          /* Skip initial channels and, for sp, the filler */
             sp += 4, dp += 3;
@@ -506,7 +564,7 @@ png_do_strip_channel(png_row_infop row_info, png_bytep row, int at_start)
 
       else if (row_info->bit_depth == 16)
       {
-         if (at_start) /* Skip initial filler */
+         if (at_start != 0) /* Skip initial filler */
             sp += 2;
          else          /* Skip initial channels and, for sp, the filler */
             sp += 8, dp += 6;
@@ -547,7 +605,7 @@ png_do_bgr(png_row_infop row_info, png_bytep row)
 {
    png_debug(1, "in png_do_bgr");
 
-   if ((row_info->color_type & PNG_COLOR_MASK_COLOR))
+   if ((row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
    {
       png_uint_32 row_width = row_info->width;
       if (row_info->bit_depth == 8)
@@ -617,16 +675,16 @@ png_do_bgr(png_row_infop row_info, png_bytep row)
 #endif
    }
 }
-#endif /* PNG_READ_BGR_SUPPORTED or PNG_WRITE_BGR_SUPPORTED */
+#endif /* READ_BGR || WRITE_BGR */
 
 #if defined(PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED) || \
     defined(PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED)
 /* Added at libpng-1.5.10 */
 void /* PRIVATE */
-png_do_check_palette_indexes(png_structp png_ptr, png_row_infop row_info)
+png_do_check_palette_indexes(png_structrp png_ptr, png_row_infop row_info)
 {
    if (png_ptr->num_palette < (1 << row_info->bit_depth) &&
-      png_ptr->num_palette_max >= 0)
+      png_ptr->num_palette > 0) /* num_palette can be 0 in MNG files */
    {
       /* Calculations moved outside switch in an attempt to stop different
        * compiler warnings.  'padding' is in *bits* within the last byte, it is
@@ -708,7 +766,7 @@ png_do_check_palette_indexes(png_structp png_ptr, png_row_infop row_info)
          {
             for (; rp > png_ptr->row_buf; rp--)
             {
-               if (*rp >= png_ptr->num_palette_max)
+               if (*rp > png_ptr->num_palette_max)
                   png_ptr->num_palette_max = (int) *rp;
             }
 
@@ -720,19 +778,30 @@ png_do_check_palette_indexes(png_structp png_ptr, png_row_infop row_info)
       }
    }
 }
-#endif /* PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED */
+#endif /* CHECK_FOR_INVALID_INDEX */
 
 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
     defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
 void PNGAPI
-png_set_user_transform_info(png_structp png_ptr, png_voidp
+png_set_user_transform_info(png_structrp png_ptr, png_voidp
    user_transform_ptr, int user_transform_depth, int user_transform_channels)
 {
    png_debug(1, "in png_set_user_transform_info");
 
    if (png_ptr == NULL)
       return;
+
+#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
+   if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
+      (png_ptr->flags & PNG_FLAG_ROW_INIT) != 0)
+   {
+      png_app_error(png_ptr,
+            "info change after png_start_read_image or png_read_update_info");
+      return;
+   }
+#endif
+
    png_ptr->user_transform_ptr = user_transform_ptr;
    png_ptr->user_transform_depth = (png_byte)user_transform_depth;
    png_ptr->user_transform_channels = (png_byte)user_transform_channels;
@@ -746,20 +815,20 @@ png_set_user_transform_info(png_structp png_ptr, png_voidp
  */
 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
 png_voidp PNGAPI
-png_get_user_transform_ptr(png_const_structp png_ptr)
+png_get_user_transform_ptr(png_const_structrp png_ptr)
 {
    if (png_ptr == NULL)
       return (NULL);
 
-   return ((png_voidp)png_ptr->user_transform_ptr);
+   return png_ptr->user_transform_ptr;
 }
 #endif
 
 #ifdef PNG_USER_TRANSFORM_INFO_SUPPORTED
 png_uint_32 PNGAPI
-png_get_current_row_number(png_const_structp png_ptr)
+png_get_current_row_number(png_const_structrp png_ptr)
 {
-   /* See the comments in png.h - this is the sub-image row when reading and
+   /* See the comments in png.h - this is the sub-image row when reading an
     * interlaced image.
     */
    if (png_ptr != NULL)
@@ -769,13 +838,12 @@ png_get_current_row_number(png_const_structp png_ptr)
 }
 
 png_byte PNGAPI
-png_get_current_pass_number(png_const_structp png_ptr)
+png_get_current_pass_number(png_const_structrp png_ptr)
 {
    if (png_ptr != NULL)
       return png_ptr->pass;
    return 8; /* invalid */
 }
-#endif /* PNG_USER_TRANSFORM_INFO_SUPPORTED */
-#endif /* PNG_READ_USER_TRANSFORM_SUPPORTED ||
-          PNG_WRITE_USER_TRANSFORM_SUPPORTED */
-#endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */
+#endif /* USER_TRANSFORM_INFO */
+#endif /* READ_USER_TRANSFORM || WRITE_USER_TRANSFORM */
+#endif /* READ || WRITE */
diff --git a/src/3rdparty/libpng/pngwio.c b/src/3rdparty/libpng/pngwio.c
index 95ffb34..0a40948 100644
--- a/src/3rdparty/libpng/pngwio.c
+++ b/src/3rdparty/libpng/pngwio.c
@@ -1,8 +1,8 @@
 
 /* pngwio.c - functions for data output
  *
- * Last changed in libpng 1.5.0 [January 6, 2011]
- * Copyright (c) 1998-2011 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.15 [November 20, 2014]
+ * Copyright (c) 1998-2014 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
@@ -30,11 +30,12 @@
  */
 
 void /* PRIVATE */
-png_write_data(png_structp png_ptr, png_const_bytep data, png_size_t length)
+png_write_data(png_structrp png_ptr, png_const_bytep data, png_size_t length)
 {
    /* NOTE: write_data_fn must not change the buffer! */
    if (png_ptr->write_data_fn != NULL )
-      (*(png_ptr->write_data_fn))(png_ptr, (png_bytep)data, length);
+      (*(png_ptr->write_data_fn))(png_ptr, png_constcast(png_bytep,data),
+         length);
 
    else
       png_error(png_ptr, "Call to NULL write function");
@@ -46,7 +47,6 @@ png_write_data(png_structp png_ptr, png_const_bytep data, png_size_t length)
  * write_data function and use it at run time with png_set_write_fn(), rather
  * than changing the library.
  */
-#ifndef USE_FAR_KEYWORD
 void PNGCBAPI
 png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
 {
@@ -60,64 +60,6 @@ png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
    if (check != length)
       png_error(png_ptr, "Write Error");
 }
-#else
-/* This is the model-independent version. Since the standard I/O library
- * can't handle far buffers in the medium and small models, we have to copy
- * the data.
- */
-
-#define NEAR_BUF_SIZE 1024
-#define MIN(a,b) (a <= b ? a : b)
-
-void PNGCBAPI
-png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
-{
-   png_uint_32 check;
-   png_byte *near_data;  /* Needs to be "png_byte *" instead of "png_bytep" */
-   png_FILE_p io_ptr;
-
-   if (png_ptr == NULL)
-      return;
-
-   /* Check if data really is near. If so, use usual code. */
-   near_data = (png_byte *)CVT_PTR_NOCHECK(data);
-   io_ptr = (png_FILE_p)CVT_PTR(png_ptr->io_ptr);
-
-   if ((png_bytep)near_data == data)
-   {
-      check = fwrite(near_data, 1, length, io_ptr);
-   }
-
-   else
-   {
-      png_byte buf[NEAR_BUF_SIZE];
-      png_size_t written, remaining, err;
-      check = 0;
-      remaining = length;
-
-      do
-      {
-         written = MIN(NEAR_BUF_SIZE, remaining);
-         png_memcpy(buf, data, written); /* Copy far buffer to near buffer */
-         err = fwrite(buf, 1, written, io_ptr);
-
-         if (err != written)
-            break;
-
-         else
-            check += err;
-
-         data += written;
-         remaining -= written;
-      }
-      while (remaining != 0);
-   }
-
-   if (check != length)
-      png_error(png_ptr, "Write Error");
-}
-
-#endif
 #endif
 
 /* This function is called to output any data pending writing (normally
@@ -126,7 +68,7 @@ png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
  */
 #ifdef PNG_WRITE_FLUSH_SUPPORTED
 void /* PRIVATE */
-png_flush(png_structp png_ptr)
+png_flush(png_structrp png_ptr)
 {
    if (png_ptr->output_flush_fn != NULL)
       (*(png_ptr->output_flush_fn))(png_ptr);
@@ -141,7 +83,7 @@ png_default_flush(png_structp png_ptr)
    if (png_ptr == NULL)
       return;
 
-   io_ptr = (png_FILE_p)CVT_PTR((png_ptr->io_ptr));
+   io_ptr = png_voidcast(png_FILE_p, (png_ptr->io_ptr));
    fflush(io_ptr);
 }
 #  endif
@@ -177,7 +119,7 @@ png_default_flush(png_structp png_ptr)
  *                 *FILE structure.
  */
 void PNGAPI
-png_set_write_fn(png_structp png_ptr, png_voidp io_ptr,
+png_set_write_fn(png_structrp png_ptr, png_voidp io_ptr,
     png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn)
 {
    if (png_ptr == NULL)
@@ -207,8 +149,11 @@ png_set_write_fn(png_structp png_ptr, png_voidp io_ptr,
 #  else
    png_ptr->output_flush_fn = output_flush_fn;
 #  endif
-#endif /* PNG_WRITE_FLUSH_SUPPORTED */
+#else
+   PNG_UNUSED(output_flush_fn)
+#endif /* WRITE_FLUSH */
 
+#ifdef PNG_READ_SUPPORTED
    /* It is an error to read while writing a png file */
    if (png_ptr->read_data_fn != NULL)
    {
@@ -218,37 +163,6 @@ png_set_write_fn(png_structp png_ptr, png_voidp io_ptr,
           "Can't set both read_data_fn and write_data_fn in the"
           " same structure");
    }
-}
-
-#ifdef USE_FAR_KEYWORD
-#  ifdef _MSC_VER
-void *png_far_to_near(png_structp png_ptr, png_voidp ptr, int check)
-{
-   void *near_ptr;
-   void FAR *far_ptr;
-   FP_OFF(near_ptr) = FP_OFF(ptr);
-   far_ptr = (void FAR *)near_ptr;
-
-   if (check != 0)
-      if (FP_SEG(ptr) != FP_SEG(far_ptr))
-         png_error(png_ptr, "segment lost in conversion");
-
-   return(near_ptr);
-}
-#  else
-void *png_far_to_near(png_structp png_ptr, png_voidp ptr, int check)
-{
-   void *near_ptr;
-   void FAR *far_ptr;
-   near_ptr = (void FAR *)ptr;
-   far_ptr = (void FAR *)near_ptr;
-
-   if (check != 0)
-      if (far_ptr != ptr)
-         png_error(png_ptr, "segment lost in conversion");
-
-   return(near_ptr);
-}
-#  endif
 #endif
-#endif /* PNG_WRITE_SUPPORTED */
+}
+#endif /* WRITE */
diff --git a/src/3rdparty/libpng/pngwrite.c b/src/3rdparty/libpng/pngwrite.c
index b587f1b..e3c2034 100644
--- a/src/3rdparty/libpng/pngwrite.c
+++ b/src/3rdparty/libpng/pngwrite.c
@@ -1,8 +1,8 @@
 
 /* pngwrite.c - general routines to write a PNG file
  *
- * Last changed in libpng 1.5.10 [March 8, 2012]
- * Copyright (c) 1998-2012 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.17 [March 26, 2015]
+ * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
@@ -12,9 +12,65 @@
  */
 
 #include "pngpriv.h"
+#if defined(PNG_SIMPLIFIED_WRITE_SUPPORTED) && defined(PNG_STDIO_SUPPORTED)
+#  include <errno.h>
+#endif
 
 #ifdef PNG_WRITE_SUPPORTED
 
+#ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
+/* Write out all the unknown chunks for the current given location */
+static void
+write_unknown_chunks(png_structrp png_ptr, png_const_inforp info_ptr,
+   unsigned int where)
+{
+   if (info_ptr->unknown_chunks_num != 0)
+   {
+      png_const_unknown_chunkp up;
+
+      png_debug(5, "writing extra chunks");
+
+      for (up = info_ptr->unknown_chunks;
+           up < info_ptr->unknown_chunks + info_ptr->unknown_chunks_num;
+           ++up)
+         if ((up->location & where) != 0)
+      {
+         /* If per-chunk unknown chunk handling is enabled use it, otherwise
+          * just write the chunks the application has set.
+          */
+#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
+         int keep = png_handle_as_unknown(png_ptr, up->name);
+
+         /* NOTE: this code is radically different from the read side in the
+          * matter of handling an ancillary unknown chunk.  In the read side
+          * the default behavior is to discard it, in the code below the default
+          * behavior is to write it.  Critical chunks are, however, only
+          * written if explicitly listed or if the default is set to write all
+          * unknown chunks.
+          *
+          * The default handling is also slightly weird - it is not possible to
+          * stop the writing of all unsafe-to-copy chunks!
+          *
+          * TODO: REVIEW: this would seem to be a bug.
+          */
+         if (keep != PNG_HANDLE_CHUNK_NEVER &&
+             ((up->name[3] & 0x20) /* safe-to-copy overrides everything */ ||
+              keep == PNG_HANDLE_CHUNK_ALWAYS ||
+              (keep == PNG_HANDLE_CHUNK_AS_DEFAULT &&
+               png_ptr->unknown_default == PNG_HANDLE_CHUNK_ALWAYS)))
+#endif
+         {
+            /* TODO: review, what is wrong with a zero length unknown chunk? */
+            if (up->size == 0)
+               png_warning(png_ptr, "Writing zero-length unknown chunk");
+
+            png_write_chunk(png_ptr, up->name, up->data, up->size);
+         }
+      }
+   }
+}
+#endif /* WRITE_UNKNOWN_CHUNKS */
+
 /* Writes all the PNG information.  This is the suggested way to use the
  * library.  If you have a new chunk to add, make a function to write it,
  * and put it in the correct location here.  If you want the chunk written
@@ -25,21 +81,21 @@
  * them in png_write_end(), and compressing them.
  */
 void PNGAPI
-png_write_info_before_PLTE(png_structp png_ptr, png_infop info_ptr)
+png_write_info_before_PLTE(png_structrp png_ptr, png_const_inforp info_ptr)
 {
    png_debug(1, "in png_write_info_before_PLTE");
 
    if (png_ptr == NULL || info_ptr == NULL)
       return;
 
-   if (!(png_ptr->mode & PNG_WROTE_INFO_BEFORE_PLTE))
+   if ((png_ptr->mode & PNG_WROTE_INFO_BEFORE_PLTE) == 0)
    {
    /* Write PNG signature */
    png_write_sig(png_ptr);
 
 #ifdef PNG_MNG_FEATURES_SUPPORTED
-   if ((png_ptr->mode&PNG_HAVE_PNG_SIGNATURE) && \
-       (png_ptr->mng_features_permitted))
+   if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0 && \
+       png_ptr->mng_features_permitted != 0)
    {
       png_warning(png_ptr, "MNG features are not allowed in a PNG datastream");
       png_ptr->mng_features_permitted = 0;
@@ -51,75 +107,88 @@ png_write_info_before_PLTE(png_structp png_ptr, png_infop info_ptr)
        info_ptr->bit_depth, info_ptr->color_type, info_ptr->compression_type,
        info_ptr->filter_type,
 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
-       info_ptr->interlace_type);
+       info_ptr->interlace_type
 #else
-       0);
+       0
 #endif
+      );
+
    /* The rest of these check to see if the valid field has the appropriate
     * flag set, and if it does, writes the chunk.
+    *
+    * 1.6.0: COLORSPACE support controls the writing of these chunks too, and
+    * the chunks will be written if the WRITE routine is there and information
+    * is available in the COLORSPACE.  (See png_colorspace_sync_info in png.c
+    * for where the valid flags get set.)
+    *
+    * Under certain circumstances the colorspace can be invalidated without
+    * syncing the info_struct 'valid' flags; this happens if libpng detects and
+    * error and calls png_error while the color space is being set, yet the
+    * application continues writing the PNG.  So check the 'invalid' flag here
+    * too.
     */
-#ifdef PNG_WRITE_gAMA_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_gAMA)
-      png_write_gAMA_fixed(png_ptr, info_ptr->gamma);
-#endif
-#ifdef PNG_WRITE_sRGB_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_sRGB)
-      png_write_sRGB(png_ptr, (int)info_ptr->srgb_intent);
+#ifdef PNG_GAMMA_SUPPORTED
+#  ifdef PNG_WRITE_gAMA_SUPPORTED
+      if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) == 0 &&
+          (info_ptr->colorspace.flags & PNG_COLORSPACE_FROM_gAMA) != 0 &&
+          (info_ptr->valid & PNG_INFO_gAMA) != 0)
+         png_write_gAMA_fixed(png_ptr, info_ptr->colorspace.gamma);
+#  endif
 #endif
 
-#ifdef PNG_WRITE_iCCP_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_iCCP)
-      png_write_iCCP(png_ptr, info_ptr->iccp_name, PNG_COMPRESSION_TYPE_BASE,
-          (png_charp)info_ptr->iccp_profile, (int)info_ptr->iccp_proflen);
-#endif
+#ifdef PNG_COLORSPACE_SUPPORTED
+   /* Write only one of sRGB or an ICC profile.  If a profile was supplied
+    * and it matches one of the known sRGB ones issue a warning.
+    */
+#  ifdef PNG_WRITE_iCCP_SUPPORTED
+      if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) == 0 &&
+          (info_ptr->valid & PNG_INFO_iCCP) != 0)
+      {
+#        ifdef PNG_WRITE_sRGB_SUPPORTED
+            if ((info_ptr->valid & PNG_INFO_sRGB) != 0)
+               png_app_warning(png_ptr,
+                  "profile matches sRGB but writing iCCP instead");
+#        endif
+
+         png_write_iCCP(png_ptr, info_ptr->iccp_name,
+            info_ptr->iccp_profile);
+      }
+#     ifdef PNG_WRITE_sRGB_SUPPORTED
+         else
+#     endif
+#  endif
+
+#  ifdef PNG_WRITE_sRGB_SUPPORTED
+      if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) == 0 &&
+          (info_ptr->valid & PNG_INFO_sRGB) != 0)
+         png_write_sRGB(png_ptr, info_ptr->colorspace.rendering_intent);
+#  endif /* WRITE_sRGB */
+#endif /* COLORSPACE */
+
 #ifdef PNG_WRITE_sBIT_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_sBIT)
+   if ((info_ptr->valid & PNG_INFO_sBIT) != 0)
       png_write_sBIT(png_ptr, &(info_ptr->sig_bit), info_ptr->color_type);
 #endif
-#ifdef PNG_WRITE_cHRM_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_cHRM)
-      png_write_cHRM_fixed(png_ptr,
-          info_ptr->x_white, info_ptr->y_white,
-          info_ptr->x_red, info_ptr->y_red,
-          info_ptr->x_green, info_ptr->y_green,
-          info_ptr->x_blue, info_ptr->y_blue);
+
+#ifdef PNG_COLORSPACE_SUPPORTED
+#  ifdef PNG_WRITE_cHRM_SUPPORTED
+      if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) == 0 &&
+         (info_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM) != 0 &&
+         (info_ptr->valid & PNG_INFO_cHRM) != 0)
+         png_write_cHRM_fixed(png_ptr, &info_ptr->colorspace.end_points_xy);
+#  endif
 #endif
 
 #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
-   if (info_ptr->unknown_chunks_num)
-   {
-      png_unknown_chunk *up;
-
-      png_debug(5, "writing extra chunks");
-
-      for (up = info_ptr->unknown_chunks;
-           up < info_ptr->unknown_chunks + info_ptr->unknown_chunks_num;
-           up++)
-      {
-         int keep = png_handle_as_unknown(png_ptr, up->name);
-
-         if (keep != PNG_HANDLE_CHUNK_NEVER &&
-             up->location &&
-             !(up->location & PNG_HAVE_PLTE) &&
-             !(up->location & PNG_HAVE_IDAT) &&
-             !(up->location & PNG_AFTER_IDAT) &&
-             ((up->name[3] & 0x20) || keep == PNG_HANDLE_CHUNK_ALWAYS ||
-             (png_ptr->flags & PNG_FLAG_KEEP_UNSAFE_CHUNKS)))
-         {
-            if (up->size == 0)
-               png_warning(png_ptr, "Writing zero-length unknown chunk");
-
-            png_write_chunk(png_ptr, up->name, up->data, up->size);
-         }
-      }
-   }
+      write_unknown_chunks(png_ptr, info_ptr, PNG_HAVE_IHDR);
 #endif
+
       png_ptr->mode |= PNG_WROTE_INFO_BEFORE_PLTE;
    }
 }
 
 void PNGAPI
-png_write_info(png_structp png_ptr, png_infop info_ptr)
+png_write_info(png_structrp png_ptr, png_const_inforp info_ptr)
 {
 #if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
    int i;
@@ -132,19 +201,19 @@ png_write_info(png_structp png_ptr, png_infop info_ptr)
 
    png_write_info_before_PLTE(png_ptr, info_ptr);
 
-   if (info_ptr->valid & PNG_INFO_PLTE)
+   if ((info_ptr->valid & PNG_INFO_PLTE) != 0)
       png_write_PLTE(png_ptr, info_ptr->palette,
           (png_uint_32)info_ptr->num_palette);
 
-   else if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+   else if ((info_ptr->color_type == PNG_COLOR_TYPE_PALETTE) !=0)
       png_error(png_ptr, "Valid palette required for paletted images");
 
 #ifdef PNG_WRITE_tRNS_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_tRNS)
+   if ((info_ptr->valid & PNG_INFO_tRNS) !=0)
    {
 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
       /* Invert the alpha channel (in tRNS) */
-      if ((png_ptr->transformations & PNG_INVERT_ALPHA) &&
+      if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0 &&
           info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
       {
          int j;
@@ -158,42 +227,42 @@ png_write_info(png_structp png_ptr, png_infop info_ptr)
    }
 #endif
 #ifdef PNG_WRITE_bKGD_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_bKGD)
+   if ((info_ptr->valid & PNG_INFO_bKGD) != 0)
       png_write_bKGD(png_ptr, &(info_ptr->background), info_ptr->color_type);
 #endif
 
 #ifdef PNG_WRITE_hIST_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_hIST)
+   if ((info_ptr->valid & PNG_INFO_hIST) != 0)
       png_write_hIST(png_ptr, info_ptr->hist, info_ptr->num_palette);
 #endif
 
 #ifdef PNG_WRITE_oFFs_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_oFFs)
+   if ((info_ptr->valid & PNG_INFO_oFFs) != 0)
       png_write_oFFs(png_ptr, info_ptr->x_offset, info_ptr->y_offset,
           info_ptr->offset_unit_type);
 #endif
 
 #ifdef PNG_WRITE_pCAL_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_pCAL)
+   if ((info_ptr->valid & PNG_INFO_pCAL) != 0)
       png_write_pCAL(png_ptr, info_ptr->pcal_purpose, info_ptr->pcal_X0,
           info_ptr->pcal_X1, info_ptr->pcal_type, info_ptr->pcal_nparams,
           info_ptr->pcal_units, info_ptr->pcal_params);
 #endif
 
 #ifdef PNG_WRITE_sCAL_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_sCAL)
+   if ((info_ptr->valid & PNG_INFO_sCAL) != 0)
       png_write_sCAL_s(png_ptr, (int)info_ptr->scal_unit,
           info_ptr->scal_s_width, info_ptr->scal_s_height);
 #endif /* sCAL */
 
 #ifdef PNG_WRITE_pHYs_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_pHYs)
+   if ((info_ptr->valid & PNG_INFO_pHYs) != 0)
       png_write_pHYs(png_ptr, info_ptr->x_pixels_per_unit,
           info_ptr->y_pixels_per_unit, info_ptr->phys_unit_type);
 #endif /* pHYs */
 
 #ifdef PNG_WRITE_tIME_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_tIME)
+   if ((info_ptr->valid & PNG_INFO_tIME) != 0)
    {
       png_write_tIME(png_ptr, &(info_ptr->mod_time));
       png_ptr->mode |= PNG_WROTE_tIME;
@@ -201,7 +270,7 @@ png_write_info(png_structp png_ptr, png_infop info_ptr)
 #endif /* tIME */
 
 #ifdef PNG_WRITE_sPLT_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_sPLT)
+   if ((info_ptr->valid & PNG_INFO_sPLT) != 0)
       for (i = 0; i < (int)info_ptr->splt_palettes_num; i++)
          png_write_sPLT(png_ptr, info_ptr->splt_palettes + i);
 #endif /* sPLT */
@@ -223,11 +292,14 @@ png_write_info(png_structp png_ptr, png_infop info_ptr)
              info_ptr->text[i].lang,
              info_ptr->text[i].lang_key,
              info_ptr->text[i].text);
+         /* Mark this chunk as written */
+         if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
+            info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
+         else
+            info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
 #else
-          png_warning(png_ptr, "Unable to write international text");
+         png_warning(png_ptr, "Unable to write international text");
 #endif
-          /* Mark this chunk as written */
-          info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
       }
 
       /* If we want a compressed text chunk */
@@ -236,13 +308,12 @@ png_write_info(png_structp png_ptr, png_infop info_ptr)
 #ifdef PNG_WRITE_zTXt_SUPPORTED
          /* Write compressed chunk */
          png_write_zTXt(png_ptr, info_ptr->text[i].key,
-             info_ptr->text[i].text, 0,
-             info_ptr->text[i].compression);
+             info_ptr->text[i].text, info_ptr->text[i].compression);
+         /* Mark this chunk as written */
+         info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
 #else
          png_warning(png_ptr, "Unable to write compressed text");
 #endif
-         /* Mark this chunk as written */
-         info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
       }
 
       else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
@@ -263,29 +334,7 @@ png_write_info(png_structp png_ptr, png_infop info_ptr)
 #endif /* tEXt */
 
 #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
-   if (info_ptr->unknown_chunks_num)
-   {
-      png_unknown_chunk *up;
-
-      png_debug(5, "writing extra chunks");
-
-      for (up = info_ptr->unknown_chunks;
-           up < info_ptr->unknown_chunks + info_ptr->unknown_chunks_num;
-           up++)
-      {
-         int keep = png_handle_as_unknown(png_ptr, up->name);
-         if (keep != PNG_HANDLE_CHUNK_NEVER &&
-             up->location &&
-             (up->location & PNG_HAVE_PLTE) &&
-             !(up->location & PNG_HAVE_IDAT) &&
-             !(up->location & PNG_AFTER_IDAT) &&
-             ((up->name[3] & 0x20) || keep == PNG_HANDLE_CHUNK_ALWAYS ||
-             (png_ptr->flags & PNG_FLAG_KEEP_UNSAFE_CHUNKS)))
-         {
-            png_write_chunk(png_ptr, up->name, up->data, up->size);
-         }
-      }
-   }
+   write_unknown_chunks(png_ptr, info_ptr, PNG_HAVE_PLTE);
 #endif
 }
 
@@ -295,14 +344,14 @@ png_write_info(png_structp png_ptr, png_infop info_ptr)
  * comments, I suggest writing them here, and compressing them.
  */
 void PNGAPI
-png_write_end(png_structp png_ptr, png_infop info_ptr)
+png_write_end(png_structrp png_ptr, png_inforp info_ptr)
 {
    png_debug(1, "in png_write_end");
 
    if (png_ptr == NULL)
       return;
 
-   if (!(png_ptr->mode & PNG_HAVE_IDAT))
+   if ((png_ptr->mode & PNG_HAVE_IDAT) == 0)
       png_error(png_ptr, "No IDATs written into file");
 
 #ifdef PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED
@@ -318,8 +367,8 @@ png_write_end(png_structp png_ptr, png_infop info_ptr)
 #endif
 #ifdef PNG_WRITE_tIME_SUPPORTED
       /* Check to see if user has supplied a time chunk */
-      if ((info_ptr->valid & PNG_INFO_tIME) &&
-          !(png_ptr->mode & PNG_WROTE_tIME))
+      if ((info_ptr->valid & PNG_INFO_tIME) != 0 &&
+          (png_ptr->mode & PNG_WROTE_tIME) == 0)
          png_write_tIME(png_ptr, &(info_ptr->mod_time));
 
 #endif
@@ -340,11 +389,14 @@ png_write_end(png_structp png_ptr, png_infop info_ptr)
                 info_ptr->text[i].lang,
                 info_ptr->text[i].lang_key,
                 info_ptr->text[i].text);
+            /* Mark this chunk as written */
+            if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
+               info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
+            else
+               info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
 #else
             png_warning(png_ptr, "Unable to write international text");
 #endif
-            /* Mark this chunk as written */
-            info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
          }
 
          else if (info_ptr->text[i].compression >= PNG_TEXT_COMPRESSION_zTXt)
@@ -352,13 +404,12 @@ png_write_end(png_structp png_ptr, png_infop info_ptr)
 #ifdef PNG_WRITE_zTXt_SUPPORTED
             /* Write compressed chunk */
             png_write_zTXt(png_ptr, info_ptr->text[i].key,
-                info_ptr->text[i].text, 0,
-                info_ptr->text[i].compression);
+                info_ptr->text[i].text, info_ptr->text[i].compression);
+            /* Mark this chunk as written */
+            info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
 #else
             png_warning(png_ptr, "Unable to write compressed text");
 #endif
-            /* Mark this chunk as written */
-            info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
          }
 
          else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
@@ -367,37 +418,16 @@ png_write_end(png_structp png_ptr, png_infop info_ptr)
             /* Write uncompressed chunk */
             png_write_tEXt(png_ptr, info_ptr->text[i].key,
                 info_ptr->text[i].text, 0);
+            /* Mark this chunk as written */
+            info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
 #else
             png_warning(png_ptr, "Unable to write uncompressed text");
 #endif
-
-            /* Mark this chunk as written */
-            info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
          }
       }
 #endif
 #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
-   if (info_ptr->unknown_chunks_num)
-   {
-      png_unknown_chunk *up;
-
-      png_debug(5, "writing extra chunks");
-
-      for (up = info_ptr->unknown_chunks;
-           up < info_ptr->unknown_chunks + info_ptr->unknown_chunks_num;
-           up++)
-      {
-         int keep = png_handle_as_unknown(png_ptr, up->name);
-         if (keep != PNG_HANDLE_CHUNK_NEVER &&
-             up->location &&
-             (up->location & PNG_AFTER_IDAT) &&
-             ((up->name[3] & 0x20) || keep == PNG_HANDLE_CHUNK_ALWAYS ||
-             (png_ptr->flags & PNG_FLAG_KEEP_UNSAFE_CHUNKS)))
-         {
-            png_write_chunk(png_ptr, up->name, up->data, up->size);
-         }
-      }
-   }
+      write_unknown_chunks(png_ptr, info_ptr, PNG_AFTER_IDAT);
 #endif
    }
 
@@ -405,6 +435,7 @@ png_write_end(png_structp png_ptr, png_infop info_ptr)
 
    /* Write end of PNG file */
    png_write_IEND(png_ptr);
+
    /* This flush, added in libpng-1.0.8, removed from libpng-1.0.9beta03,
     * and restored again in libpng-1.2.30, may cause some applications that
     * do not set png_ptr->output_flush_fn to crash.  If your application
@@ -420,9 +451,8 @@ png_write_end(png_structp png_ptr, png_infop info_ptr)
 }
 
 #ifdef PNG_CONVERT_tIME_SUPPORTED
-/* "tm" structure is not supported on WindowsCE */
 void PNGAPI
-png_convert_from_struct_tm(png_timep ptime, PNG_CONST struct tm FAR * ttime)
+png_convert_from_struct_tm(png_timep ptime, PNG_CONST struct tm * ttime)
 {
    png_debug(1, "in png_convert_from_struct_tm");
 
@@ -451,104 +481,75 @@ PNG_FUNCTION(png_structp,PNGAPI
 png_create_write_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
     png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED)
 {
-#ifdef PNG_USER_MEM_SUPPORTED
-   return (png_create_write_struct_2(user_png_ver, error_ptr, error_fn,
-       warn_fn, NULL, NULL, NULL));
+#ifndef PNG_USER_MEM_SUPPORTED
+   png_structrp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
+       error_fn, warn_fn, NULL, NULL, NULL);
+#else
+   return png_create_write_struct_2(user_png_ver, error_ptr, error_fn,
+       warn_fn, NULL, NULL, NULL);
 }
 
 /* Alternate initialize png_ptr structure, and allocate any memory needed */
-static void png_reset_filter_heuristics(png_structp png_ptr); /* forward decl */
-
 PNG_FUNCTION(png_structp,PNGAPI
 png_create_write_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
     png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
     png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
 {
-#endif /* PNG_USER_MEM_SUPPORTED */
-   volatile int png_cleanup_needed = 0;
-#ifdef PNG_SETJMP_SUPPORTED
-   volatile
-#endif
-   png_structp png_ptr;
-#ifdef PNG_SETJMP_SUPPORTED
-#ifdef USE_FAR_KEYWORD
-   jmp_buf tmp_jmpbuf;
-#endif
-#endif
-
-   png_debug(1, "in png_create_write_struct");
-
-#ifdef PNG_USER_MEM_SUPPORTED
-   png_ptr = (png_structp)png_create_struct_2(PNG_STRUCT_PNG,
-       (png_malloc_ptr)malloc_fn, (png_voidp)mem_ptr);
-#else
-   png_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG);
-#endif /* PNG_USER_MEM_SUPPORTED */
-   if (png_ptr == NULL)
-      return (NULL);
+   png_structrp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
+       error_fn, warn_fn, mem_ptr, malloc_fn, free_fn);
+#endif /* USER_MEM */
+   if (png_ptr != NULL)
+   {
+      /* Set the zlib control values to defaults; they can be overridden by the
+       * application after the struct has been created.
+       */
+      png_ptr->zbuffer_size = PNG_ZBUF_SIZE;
 
-   /* Added at libpng-1.2.6 */
-#ifdef PNG_SET_USER_LIMITS_SUPPORTED
-   png_ptr->user_width_max = PNG_USER_WIDTH_MAX;
-   png_ptr->user_height_max = PNG_USER_HEIGHT_MAX;
+      /* The 'zlib_strategy' setting is irrelevant because png_default_claim in
+       * pngwutil.c defaults it according to whether or not filters will be
+       * used, and ignores this setting.
+       */
+      png_ptr->zlib_strategy = PNG_Z_DEFAULT_STRATEGY;
+      png_ptr->zlib_level = PNG_Z_DEFAULT_COMPRESSION;
+      png_ptr->zlib_mem_level = 8;
+      png_ptr->zlib_window_bits = 15;
+      png_ptr->zlib_method = 8;
+
+#ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
+      png_ptr->zlib_text_strategy = PNG_TEXT_Z_DEFAULT_STRATEGY;
+      png_ptr->zlib_text_level = PNG_TEXT_Z_DEFAULT_COMPRESSION;
+      png_ptr->zlib_text_mem_level = 8;
+      png_ptr->zlib_text_window_bits = 15;
+      png_ptr->zlib_text_method = 8;
+#endif /* WRITE_COMPRESSED_TEXT */
+
+      /* This is a highly dubious configuration option; by default it is off,
+       * but it may be appropriate for private builds that are testing
+       * extensions not conformant to the current specification, or of
+       * applications that must not fail to write at all costs!
+       */
+#ifdef PNG_BENIGN_WRITE_ERRORS_SUPPORTED
+      /* In stable builds only warn if an application error can be completely
+       * handled.
+       */
+      png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN;
 #endif
 
-#ifdef PNG_SETJMP_SUPPORTED
-/* Applications that neglect to set up their own setjmp() and then
- * encounter a png_error() will longjmp here.  Since the jmpbuf is
- * then meaningless we abort instead of returning.
- */
-#ifdef USE_FAR_KEYWORD
-   if (setjmp(tmp_jmpbuf))
-#else
-   if (setjmp(png_jmpbuf(png_ptr))) /* sets longjmp to match setjmp */
-#endif
-#ifdef USE_FAR_KEYWORD
-   png_memcpy(png_jmpbuf(png_ptr), tmp_jmpbuf, png_sizeof(jmp_buf));
-#endif
-      PNG_ABORT();
+      /* App warnings are warnings in release (or release candidate) builds but
+       * are errors during development.
+       */
+#if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC
+      png_ptr->flags |= PNG_FLAG_APP_WARNINGS_WARN;
 #endif
 
-#ifdef PNG_USER_MEM_SUPPORTED
-   png_set_mem_fn(png_ptr, mem_ptr, malloc_fn, free_fn);
-#endif /* PNG_USER_MEM_SUPPORTED */
-   png_set_error_fn(png_ptr, error_ptr, error_fn, warn_fn);
-
-   if (!png_user_version_check(png_ptr, user_png_ver))
-      png_cleanup_needed = 1;
-
-   /* Initialize zbuf - compression buffer */
-   png_ptr->zbuf_size = PNG_ZBUF_SIZE;
-
-   if (!png_cleanup_needed)
-   {
-      png_ptr->zbuf = (png_bytep)png_malloc_warn(png_ptr,
-          png_ptr->zbuf_size);
-      if (png_ptr->zbuf == NULL)
-         png_cleanup_needed = 1;
-   }
-
-   if (png_cleanup_needed)
-   {
-       /* Clean up PNG structure and deallocate any memory. */
-       png_free(png_ptr, png_ptr->zbuf);
-       png_ptr->zbuf = NULL;
-#ifdef PNG_USER_MEM_SUPPORTED
-       png_destroy_struct_2((png_voidp)png_ptr,
-           (png_free_ptr)free_fn, (png_voidp)mem_ptr);
-#else
-       png_destroy_struct((png_voidp)png_ptr);
-#endif
-       return (NULL);
+      /* TODO: delay this, it can be done in png_init_io() (if the app doesn't
+       * do it itself) avoiding setting the default function if it is not
+       * required.
+       */
+      png_set_write_fn(png_ptr, NULL, NULL, NULL);
    }
 
-   png_set_write_fn(png_ptr, NULL, NULL, NULL);
-
-#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
-   png_reset_filter_heuristics(png_ptr);
-#endif
-
-   return (png_ptr);
+   return png_ptr;
 }
 
 
@@ -558,7 +559,7 @@ png_create_write_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
  * "write" the image seven times.
  */
 void PNGAPI
-png_write_rows(png_structp png_ptr, png_bytepp row,
+png_write_rows(png_structrp png_ptr, png_bytepp row,
     png_uint_32 num_rows)
 {
    png_uint_32 i; /* row counter */
@@ -580,7 +581,7 @@ png_write_rows(png_structp png_ptr, png_bytepp row,
  * if you are writing an interlaced image.
  */
 void PNGAPI
-png_write_image(png_structp png_ptr, png_bytepp image)
+png_write_image(png_structrp png_ptr, png_bytepp image)
 {
    png_uint_32 i; /* row index */
    int pass, num_pass; /* pass variables */
@@ -610,9 +611,74 @@ png_write_image(png_structp png_ptr, png_bytepp image)
    }
 }
 
+#ifdef PNG_MNG_FEATURES_SUPPORTED
+/* Performs intrapixel differencing  */
+static void
+png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
+{
+   png_debug(1, "in png_do_write_intrapixel");
+
+   if ((row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
+   {
+      int bytes_per_pixel;
+      png_uint_32 row_width = row_info->width;
+      if (row_info->bit_depth == 8)
+      {
+         png_bytep rp;
+         png_uint_32 i;
+
+         if (row_info->color_type == PNG_COLOR_TYPE_RGB)
+            bytes_per_pixel = 3;
+
+         else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+            bytes_per_pixel = 4;
+
+         else
+            return;
+
+         for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
+         {
+            *(rp)     = (png_byte)(*rp       - *(rp + 1));
+            *(rp + 2) = (png_byte)(*(rp + 2) - *(rp + 1));
+         }
+      }
+
+#ifdef PNG_WRITE_16BIT_SUPPORTED
+      else if (row_info->bit_depth == 16)
+      {
+         png_bytep rp;
+         png_uint_32 i;
+
+         if (row_info->color_type == PNG_COLOR_TYPE_RGB)
+            bytes_per_pixel = 6;
+
+         else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+            bytes_per_pixel = 8;
+
+         else
+            return;
+
+         for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
+         {
+            png_uint_32 s0   = (*(rp    ) << 8) | *(rp + 1);
+            png_uint_32 s1   = (*(rp + 2) << 8) | *(rp + 3);
+            png_uint_32 s2   = (*(rp + 4) << 8) | *(rp + 5);
+            png_uint_32 red  = (png_uint_32)((s0 - s1) & 0xffffL);
+            png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
+            *(rp    ) = (png_byte)(red >> 8);
+            *(rp + 1) = (png_byte)red;
+            *(rp + 4) = (png_byte)(blue >> 8);
+            *(rp + 5) = (png_byte)blue;
+         }
+      }
+#endif /* WRITE_16BIT */
+   }
+}
+#endif /* MNG_FEATURES */
+
 /* Called by user to write a row of image data */
 void PNGAPI
-png_write_row(png_structp png_ptr, png_const_bytep row)
+png_write_row(png_structrp png_ptr, png_const_bytep row)
 {
    /* 1.5.6: moved from png_struct to be a local structure: */
    png_row_info row_info;
@@ -627,44 +693,44 @@ png_write_row(png_structp png_ptr, png_const_bytep row)
    if (png_ptr->row_number == 0 && png_ptr->pass == 0)
    {
       /* Make sure we wrote the header info */
-      if (!(png_ptr->mode & PNG_WROTE_INFO_BEFORE_PLTE))
+      if ((png_ptr->mode & PNG_WROTE_INFO_BEFORE_PLTE) == 0)
          png_error(png_ptr,
              "png_write_info was never called before png_write_row");
 
       /* Check for transforms that have been set but were defined out */
 #if !defined(PNG_WRITE_INVERT_SUPPORTED) && defined(PNG_READ_INVERT_SUPPORTED)
-      if (png_ptr->transformations & PNG_INVERT_MONO)
+      if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
          png_warning(png_ptr, "PNG_WRITE_INVERT_SUPPORTED is not defined");
 #endif
 
 #if !defined(PNG_WRITE_FILLER_SUPPORTED) && defined(PNG_READ_FILLER_SUPPORTED)
-      if (png_ptr->transformations & PNG_FILLER)
+      if ((png_ptr->transformations & PNG_FILLER) != 0)
          png_warning(png_ptr, "PNG_WRITE_FILLER_SUPPORTED is not defined");
 #endif
 #if !defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
     defined(PNG_READ_PACKSWAP_SUPPORTED)
-      if (png_ptr->transformations & PNG_PACKSWAP)
+      if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
          png_warning(png_ptr,
              "PNG_WRITE_PACKSWAP_SUPPORTED is not defined");
 #endif
 
 #if !defined(PNG_WRITE_PACK_SUPPORTED) && defined(PNG_READ_PACK_SUPPORTED)
-      if (png_ptr->transformations & PNG_PACK)
+      if ((png_ptr->transformations & PNG_PACK) != 0)
          png_warning(png_ptr, "PNG_WRITE_PACK_SUPPORTED is not defined");
 #endif
 
 #if !defined(PNG_WRITE_SHIFT_SUPPORTED) && defined(PNG_READ_SHIFT_SUPPORTED)
-      if (png_ptr->transformations & PNG_SHIFT)
+      if ((png_ptr->transformations & PNG_SHIFT) != 0)
          png_warning(png_ptr, "PNG_WRITE_SHIFT_SUPPORTED is not defined");
 #endif
 
 #if !defined(PNG_WRITE_BGR_SUPPORTED) && defined(PNG_READ_BGR_SUPPORTED)
-      if (png_ptr->transformations & PNG_BGR)
+      if ((png_ptr->transformations & PNG_BGR) != 0)
          png_warning(png_ptr, "PNG_WRITE_BGR_SUPPORTED is not defined");
 #endif
 
 #if !defined(PNG_WRITE_SWAP_SUPPORTED) && defined(PNG_READ_SWAP_SUPPORTED)
-      if (png_ptr->transformations & PNG_SWAP_BYTES)
+      if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
          png_warning(png_ptr, "PNG_WRITE_SWAP_SUPPORTED is not defined");
 #endif
 
@@ -673,12 +739,13 @@ png_write_row(png_structp png_ptr, png_const_bytep row)
 
 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
    /* If interlaced and not interested in row, return */
-   if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
+   if (png_ptr->interlaced != 0 &&
+       (png_ptr->transformations & PNG_INTERLACE) != 0)
    {
       switch (png_ptr->pass)
       {
          case 0:
-            if (png_ptr->row_number & 0x07)
+            if ((png_ptr->row_number & 0x07) != 0)
             {
                png_write_finish_row(png_ptr);
                return;
@@ -686,7 +753,7 @@ png_write_row(png_structp png_ptr, png_const_bytep row)
             break;
 
          case 1:
-            if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
+            if ((png_ptr->row_number & 0x07) != 0 || png_ptr->width < 5)
             {
                png_write_finish_row(png_ptr);
                return;
@@ -702,7 +769,7 @@ png_write_row(png_structp png_ptr, png_const_bytep row)
             break;
 
          case 3:
-            if ((png_ptr->row_number & 0x03) || png_ptr->width < 3)
+            if ((png_ptr->row_number & 0x03) != 0 || png_ptr->width < 3)
             {
                png_write_finish_row(png_ptr);
                return;
@@ -718,7 +785,7 @@ png_write_row(png_structp png_ptr, png_const_bytep row)
             break;
 
          case 5:
-            if ((png_ptr->row_number & 0x01) || png_ptr->width < 2)
+            if ((png_ptr->row_number & 0x01) != 0 || png_ptr->width < 2)
             {
                png_write_finish_row(png_ptr);
                return;
@@ -726,7 +793,7 @@ png_write_row(png_structp png_ptr, png_const_bytep row)
             break;
 
          case 6:
-            if (!(png_ptr->row_number & 0x01))
+            if ((png_ptr->row_number & 0x01) == 0)
             {
                png_write_finish_row(png_ptr);
                return;
@@ -755,16 +822,16 @@ png_write_row(png_structp png_ptr, png_const_bytep row)
    png_debug1(3, "row_info->rowbytes = %lu", (unsigned long)row_info.rowbytes);
 
    /* Copy user's row into buffer, leaving room for filter byte. */
-   png_memcpy(png_ptr->row_buf + 1, row, row_info.rowbytes);
+   memcpy(png_ptr->row_buf + 1, row, row_info.rowbytes);
 
 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
    /* Handle interlacing */
    if (png_ptr->interlaced && png_ptr->pass < 6 &&
-       (png_ptr->transformations & PNG_INTERLACE))
+       (png_ptr->transformations & PNG_INTERLACE) != 0)
    {
       png_do_write_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass);
       /* This should always get caught above, but still ... */
-      if (!(row_info.width))
+      if (row_info.width == 0)
       {
          png_write_finish_row(png_ptr);
          return;
@@ -774,7 +841,7 @@ png_write_row(png_structp png_ptr, png_const_bytep row)
 
 #ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
    /* Handle other transformations */
-   if (png_ptr->transformations)
+   if (png_ptr->transformations != 0)
       png_do_write_transformations(png_ptr, &row_info);
 #endif
 
@@ -795,7 +862,7 @@ png_write_row(png_structp png_ptr, png_const_bytep row)
     * 4. The filter_method is 64 and
     * 5. The color_type is RGB or RGBA
     */
-   if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
+   if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
        (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
    {
       /* Intrapixel differencing */
@@ -806,7 +873,8 @@ png_write_row(png_structp png_ptr, png_const_bytep row)
 /* Added at libpng-1.5.10 */
 #ifdef PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED
    /* Check for out-of-range palette index */
-   if(row_info.color_type == PNG_COLOR_TYPE_PALETTE)
+   if (row_info.color_type == PNG_COLOR_TYPE_PALETTE &&
+       png_ptr->num_palette_max >= 0)
       png_do_check_palette_indexes(png_ptr, &row_info);
 #endif
 
@@ -820,7 +888,7 @@ png_write_row(png_structp png_ptr, png_const_bytep row)
 #ifdef PNG_WRITE_FLUSH_SUPPORTED
 /* Set the automatic flush interval or 0 to turn flushing off */
 void PNGAPI
-png_set_flush(png_structp png_ptr, int nrows)
+png_set_flush(png_structrp png_ptr, int nrows)
 {
    png_debug(1, "in png_set_flush");
 
@@ -832,10 +900,8 @@ png_set_flush(png_structp png_ptr, int nrows)
 
 /* Flush the current output buffers now */
 void PNGAPI
-png_write_flush(png_structp png_ptr)
+png_write_flush(png_structrp png_ptr)
 {
-   int wrote_IDAT;
-
    png_debug(1, "in png_write_flush");
 
    if (png_ptr == NULL)
@@ -845,140 +911,41 @@ png_write_flush(png_structp png_ptr)
    if (png_ptr->row_number >= png_ptr->num_rows)
       return;
 
-   do
-   {
-      int ret;
-
-      /* Compress the data */
-      ret = deflate(&png_ptr->zstream, Z_SYNC_FLUSH);
-      wrote_IDAT = 0;
-
-      /* Check for compression errors */
-      if (ret != Z_OK)
-      {
-         if (png_ptr->zstream.msg != NULL)
-            png_error(png_ptr, png_ptr->zstream.msg);
-
-         else
-            png_error(png_ptr, "zlib error");
-      }
-
-      if (!(png_ptr->zstream.avail_out))
-      {
-         /* Write the IDAT and reset the zlib output buffer */
-         png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
-         wrote_IDAT = 1;
-      }
-   } while (wrote_IDAT == 1);
-
-   /* If there is any data left to be output, write it into a new IDAT */
-   if (png_ptr->zbuf_size != png_ptr->zstream.avail_out)
-   {
-      /* Write the IDAT and reset the zlib output buffer */
-      png_write_IDAT(png_ptr, png_ptr->zbuf,
-          png_ptr->zbuf_size - png_ptr->zstream.avail_out);
-   }
+   png_compress_IDAT(png_ptr, NULL, 0, Z_SYNC_FLUSH);
    png_ptr->flush_rows = 0;
    png_flush(png_ptr);
 }
-#endif /* PNG_WRITE_FLUSH_SUPPORTED */
-
-/* Free all memory used by the write */
-void PNGAPI
-png_destroy_write_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr)
-{
-   png_structp png_ptr = NULL;
-   png_infop info_ptr = NULL;
-#ifdef PNG_USER_MEM_SUPPORTED
-   png_free_ptr free_fn = NULL;
-   png_voidp mem_ptr = NULL;
-#endif
-
-   png_debug(1, "in png_destroy_write_struct");
-
-   if (png_ptr_ptr != NULL)
-      png_ptr = *png_ptr_ptr;
+#endif /* WRITE_FLUSH */
 
-#ifdef PNG_USER_MEM_SUPPORTED
-   if (png_ptr != NULL)
-   {
-      free_fn = png_ptr->free_fn;
-      mem_ptr = png_ptr->mem_ptr;
-   }
-#endif
-
-   if (info_ptr_ptr != NULL)
-      info_ptr = *info_ptr_ptr;
-
-   if (info_ptr != NULL)
-   {
-      if (png_ptr != NULL)
-      {
-         png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
-
-#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
-         if (png_ptr->num_chunk_list)
-         {
-            png_free(png_ptr, png_ptr->chunk_list);
-            png_ptr->num_chunk_list = 0;
-         }
-#endif
-      }
-
-#ifdef PNG_USER_MEM_SUPPORTED
-      png_destroy_struct_2((png_voidp)info_ptr, (png_free_ptr)free_fn,
-          (png_voidp)mem_ptr);
-#else
-      png_destroy_struct((png_voidp)info_ptr);
-#endif
-      *info_ptr_ptr = NULL;
-   }
-
-   if (png_ptr != NULL)
-   {
-      png_write_destroy(png_ptr);
-#ifdef PNG_USER_MEM_SUPPORTED
-      png_destroy_struct_2((png_voidp)png_ptr, (png_free_ptr)free_fn,
-          (png_voidp)mem_ptr);
-#else
-      png_destroy_struct((png_voidp)png_ptr);
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
+static void png_reset_filter_heuristics(png_structrp png_ptr);/* forward decl */
 #endif
-      *png_ptr_ptr = NULL;
-   }
-}
 
-
-/* Free any memory used in png_ptr struct (old method) */
-void /* PRIVATE */
-png_write_destroy(png_structp png_ptr)
+/* Free any memory used in png_ptr struct without freeing the struct itself. */
+static void
+png_write_destroy(png_structrp png_ptr)
 {
-#ifdef PNG_SETJMP_SUPPORTED
-   jmp_buf tmp_jmp; /* Save jump buffer */
-#endif
-   png_error_ptr error_fn;
-#ifdef PNG_WARNINGS_SUPPORTED
-   png_error_ptr warning_fn;
-#endif
-   png_voidp error_ptr;
-#ifdef PNG_USER_MEM_SUPPORTED
-   png_free_ptr free_fn;
-#endif
-
    png_debug(1, "in png_write_destroy");
 
    /* Free any memory zlib uses */
-   if (png_ptr->zlib_state != PNG_ZLIB_UNINITIALIZED)
+   if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
       deflateEnd(&png_ptr->zstream);
 
    /* Free our memory.  png_free checks NULL for us. */
-   png_free(png_ptr, png_ptr->zbuf);
+   png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list);
    png_free(png_ptr, png_ptr->row_buf);
+   png_ptr->row_buf = NULL;
 #ifdef PNG_WRITE_FILTER_SUPPORTED
    png_free(png_ptr, png_ptr->prev_row);
    png_free(png_ptr, png_ptr->sub_row);
    png_free(png_ptr, png_ptr->up_row);
    png_free(png_ptr, png_ptr->avg_row);
    png_free(png_ptr, png_ptr->paeth_row);
+   png_ptr->prev_row = NULL;
+   png_ptr->sub_row = NULL;
+   png_ptr->up_row = NULL;
+   png_ptr->avg_row = NULL;
+   png_ptr->paeth_row = NULL;
 #endif
 
 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
@@ -986,41 +953,51 @@ png_write_destroy(png_structp png_ptr)
    png_reset_filter_heuristics(png_ptr);
    png_free(png_ptr, png_ptr->filter_costs);
    png_free(png_ptr, png_ptr->inv_filter_costs);
+   png_ptr->filter_costs = NULL;
+   png_ptr->inv_filter_costs = NULL;
 #endif
 
-#ifdef PNG_SETJMP_SUPPORTED
-   /* Reset structure */
-   png_memcpy(tmp_jmp, png_ptr->longjmp_buffer, png_sizeof(jmp_buf));
+#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
+   png_free(png_ptr, png_ptr->chunk_list);
+   png_ptr->chunk_list = NULL;
 #endif
 
-   error_fn = png_ptr->error_fn;
-#ifdef PNG_WARNINGS_SUPPORTED
-   warning_fn = png_ptr->warning_fn;
-#endif
-   error_ptr = png_ptr->error_ptr;
-#ifdef PNG_USER_MEM_SUPPORTED
-   free_fn = png_ptr->free_fn;
-#endif
+   /* The error handling and memory handling information is left intact at this
+    * point: the jmp_buf may still have to be freed.  See png_destroy_png_struct
+    * for how this happens.
+    */
+}
 
-   png_memset(png_ptr, 0, png_sizeof(png_struct));
+/* Free all memory used by the write.
+ * In libpng 1.6.0 this API changed quietly to no longer accept a NULL value for
+ * *png_ptr_ptr.  Prior to 1.6.0 it would accept such a value and it would free
+ * the passed in info_structs but it would quietly fail to free any of the data
+ * inside them.  In 1.6.0 it quietly does nothing (it has to be quiet because it
+ * has no png_ptr.)
+ */
+void PNGAPI
+png_destroy_write_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr)
+{
+   png_debug(1, "in png_destroy_write_struct");
 
-   png_ptr->error_fn = error_fn;
-#ifdef PNG_WARNINGS_SUPPORTED
-   png_ptr->warning_fn = warning_fn;
-#endif
-   png_ptr->error_ptr = error_ptr;
-#ifdef PNG_USER_MEM_SUPPORTED
-   png_ptr->free_fn = free_fn;
-#endif
+   if (png_ptr_ptr != NULL)
+   {
+      png_structrp png_ptr = *png_ptr_ptr;
 
-#ifdef PNG_SETJMP_SUPPORTED
-   png_memcpy(png_ptr->longjmp_buffer, tmp_jmp, png_sizeof(jmp_buf));
-#endif
+      if (png_ptr != NULL) /* added in libpng 1.6.0 */
+      {
+         png_destroy_info_struct(png_ptr, info_ptr_ptr);
+
+         *png_ptr_ptr = NULL;
+         png_write_destroy(png_ptr);
+         png_destroy_png_struct(png_ptr);
+      }
+   }
 }
 
 /* Allow the application to select one or more row filters to use. */
 void PNGAPI
-png_set_filter(png_structp png_ptr, int method, int filters)
+png_set_filter(png_structrp png_ptr, int method, int filters)
 {
    png_debug(1, "in png_set_filter");
 
@@ -1028,7 +1005,7 @@ png_set_filter(png_structp png_ptr, int method, int filters)
       return;
 
 #ifdef PNG_MNG_FEATURES_SUPPORTED
-   if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
+   if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
        (method == PNG_INTRAPIXEL_DIFFERENCING))
       method = PNG_FILTER_TYPE_BASE;
 
@@ -1040,8 +1017,9 @@ png_set_filter(png_structp png_ptr, int method, int filters)
 #ifdef PNG_WRITE_FILTER_SUPPORTED
          case 5:
          case 6:
-         case 7: png_warning(png_ptr, "Unknown row filter for method 0");
-#endif /* PNG_WRITE_FILTER_SUPPORTED */
+         case 7: png_app_error(png_ptr, "Unknown row filter for method 0");
+            /* FALL THROUGH */
+#endif /* WRITE_FILTER */
          case PNG_FILTER_VALUE_NONE:
             png_ptr->do_filter = PNG_FILTER_NONE; break;
 
@@ -1062,8 +1040,8 @@ png_set_filter(png_structp png_ptr, int method, int filters)
             png_ptr->do_filter = (png_byte)filters; break;
 #else
          default:
-            png_warning(png_ptr, "Unknown row filter for method 0");
-#endif /* PNG_WRITE_FILTER_SUPPORTED */
+            png_app_error(png_ptr, "Unknown row filter for method 0");
+#endif /* WRITE_FILTER */
       }
 
       /* If we have allocated the row_buf, this means we have already started
@@ -1072,20 +1050,22 @@ png_set_filter(png_structp png_ptr, int method, int filters)
        * it is too late to start using the filters that need it, since we
        * will be missing the data in the previous row.  If an application
        * wants to start and stop using particular filters during compression,
-       * it should start out with all of the filters, and then add and
-       * remove them after the start of compression.
+       * it should start out with all of the filters, and then remove them
+       * or add them back after the start of compression.
        */
       if (png_ptr->row_buf != NULL)
       {
 #ifdef PNG_WRITE_FILTER_SUPPORTED
-         if ((png_ptr->do_filter & PNG_FILTER_SUB) && png_ptr->sub_row == NULL)
+         if ((png_ptr->do_filter & PNG_FILTER_SUB) != 0 &&
+             png_ptr->sub_row == NULL)
          {
             png_ptr->sub_row = (png_bytep)png_malloc(png_ptr,
                 (png_ptr->rowbytes + 1));
             png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB;
          }
 
-         if ((png_ptr->do_filter & PNG_FILTER_UP) && png_ptr->up_row == NULL)
+         if ((png_ptr->do_filter & PNG_FILTER_UP) != 0 &&
+              png_ptr->up_row == NULL)
          {
             if (png_ptr->prev_row == NULL)
             {
@@ -1102,7 +1082,8 @@ png_set_filter(png_structp png_ptr, int method, int filters)
             }
          }
 
-         if ((png_ptr->do_filter & PNG_FILTER_AVG) && png_ptr->avg_row == NULL)
+         if ((png_ptr->do_filter & PNG_FILTER_AVG) != 0 &&
+              png_ptr->avg_row == NULL)
          {
             if (png_ptr->prev_row == NULL)
             {
@@ -1119,7 +1100,7 @@ png_set_filter(png_structp png_ptr, int method, int filters)
             }
          }
 
-         if ((png_ptr->do_filter & PNG_FILTER_PAETH) &&
+         if ((png_ptr->do_filter & PNG_FILTER_PAETH) != 0 &&
              png_ptr->paeth_row == NULL)
          {
             if (png_ptr->prev_row == NULL)
@@ -1137,7 +1118,7 @@ png_set_filter(png_structp png_ptr, int method, int filters)
          }
 
          if (png_ptr->do_filter == PNG_NO_FILTERS)
-#endif /* PNG_WRITE_FILTER_SUPPORTED */
+#endif /* WRITE_FILTER */
             png_ptr->do_filter = PNG_FILTER_NONE;
       }
    }
@@ -1155,7 +1136,7 @@ png_set_filter(png_structp png_ptr, int method, int filters)
 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED      /* GRR 970116 */
 /* Convenience reset API. */
 static void
-png_reset_filter_heuristics(png_structp png_ptr)
+png_reset_filter_heuristics(png_structrp png_ptr)
 {
    /* Clear out any old values in the 'weights' - this must be done because if
     * the app calls set_filter_heuristics multiple times with different
@@ -1188,7 +1169,7 @@ png_reset_filter_heuristics(png_structp png_ptr)
 }
 
 static int
-png_init_filter_heuristics(png_structp png_ptr, int heuristic_method,
+png_init_filter_heuristics(png_structrp png_ptr, int heuristic_method,
    int num_weights)
 {
    if (png_ptr == NULL)
@@ -1208,7 +1189,7 @@ png_init_filter_heuristics(png_structp png_ptr, int heuristic_method,
       if (num_weights > 0)
       {
          png_ptr->prev_filters = (png_bytep)png_malloc(png_ptr,
-             (png_uint_32)(png_sizeof(png_byte) * num_weights));
+             (png_uint_32)((sizeof (png_byte)) * num_weights));
 
          /* To make sure that the weighting starts out fairly */
          for (i = 0; i < num_weights; i++)
@@ -1217,10 +1198,10 @@ png_init_filter_heuristics(png_structp png_ptr, int heuristic_method,
          }
 
          png_ptr->filter_weights = (png_uint_16p)png_malloc(png_ptr,
-             (png_uint_32)(png_sizeof(png_uint_16) * num_weights));
+             (png_uint_32)((sizeof (png_uint_16)) * num_weights));
 
          png_ptr->inv_filter_weights = (png_uint_16p)png_malloc(png_ptr,
-             (png_uint_32)(png_sizeof(png_uint_16) * num_weights));
+             (png_uint_32)((sizeof (png_uint_16)) * num_weights));
 
          for (i = 0; i < num_weights; i++)
          {
@@ -1238,10 +1219,10 @@ png_init_filter_heuristics(png_structp png_ptr, int heuristic_method,
       if (png_ptr->filter_costs == NULL)
       {
          png_ptr->filter_costs = (png_uint_16p)png_malloc(png_ptr,
-             (png_uint_32)(png_sizeof(png_uint_16) * PNG_FILTER_VALUE_LAST));
+             (png_uint_32)((sizeof (png_uint_16)) * PNG_FILTER_VALUE_LAST));
 
          png_ptr->inv_filter_costs = (png_uint_16p)png_malloc(png_ptr,
-             (png_uint_32)(png_sizeof(png_uint_16) * PNG_FILTER_VALUE_LAST));
+             (png_uint_32)((sizeof (png_uint_16)) * PNG_FILTER_VALUE_LAST));
       }
 
       for (i = 0; i < PNG_FILTER_VALUE_LAST; i++)
@@ -1271,7 +1252,7 @@ png_init_filter_heuristics(png_structp png_ptr, int heuristic_method,
 /* Provide floating and fixed point APIs */
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 void PNGAPI
-png_set_filter_heuristics(png_structp png_ptr, int heuristic_method,
+png_set_filter_heuristics(png_structrp png_ptr, int heuristic_method,
     int num_weights, png_const_doublep filter_weights,
     png_const_doublep filter_costs)
 {
@@ -1280,7 +1261,7 @@ png_set_filter_heuristics(png_structp png_ptr, int heuristic_method,
    /* The internal API allocates all the arrays and ensures that the elements of
     * those arrays are set to the default value.
     */
-   if (!png_init_filter_heuristics(png_ptr, heuristic_method, num_weights))
+   if (png_init_filter_heuristics(png_ptr, heuristic_method, num_weights) == 0)
       return;
 
    /* If using the weighted method copy in the weights. */
@@ -1326,7 +1307,7 @@ png_set_filter_heuristics(png_structp png_ptr, int heuristic_method,
 
 #ifdef PNG_FIXED_POINT_SUPPORTED
 void PNGAPI
-png_set_filter_heuristics_fixed(png_structp png_ptr, int heuristic_method,
+png_set_filter_heuristics_fixed(png_structrp png_ptr, int heuristic_method,
     int num_weights, png_const_fixed_point_p filter_weights,
     png_const_fixed_point_p filter_costs)
 {
@@ -1335,7 +1316,7 @@ png_set_filter_heuristics_fixed(png_structp png_ptr, int heuristic_method,
    /* The internal API allocates all the arrays and ensures that the elements of
     * those arrays are set to the default value.
     */
-   if (!png_init_filter_heuristics(png_ptr, heuristic_method, num_weights))
+   if (png_init_filter_heuristics(png_ptr, heuristic_method, num_weights) == 0)
       return;
 
    /* If using the weighted method copy in the weights. */
@@ -1389,40 +1370,41 @@ png_set_filter_heuristics_fixed(png_structp png_ptr, int heuristic_method,
    }
 }
 #endif /* FIXED_POINT */
-#endif /* PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */
+#endif /* WRITE_WEIGHTED_FILTER */
 
+#ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED
 void PNGAPI
-png_set_compression_level(png_structp png_ptr, int level)
+png_set_compression_level(png_structrp png_ptr, int level)
 {
    png_debug(1, "in png_set_compression_level");
 
    if (png_ptr == NULL)
       return;
 
-   png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_LEVEL;
    png_ptr->zlib_level = level;
 }
 
 void PNGAPI
-png_set_compression_mem_level(png_structp png_ptr, int mem_level)
+png_set_compression_mem_level(png_structrp png_ptr, int mem_level)
 {
    png_debug(1, "in png_set_compression_mem_level");
 
    if (png_ptr == NULL)
       return;
 
-   png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL;
    png_ptr->zlib_mem_level = mem_level;
 }
 
 void PNGAPI
-png_set_compression_strategy(png_structp png_ptr, int strategy)
+png_set_compression_strategy(png_structrp png_ptr, int strategy)
 {
    png_debug(1, "in png_set_compression_strategy");
 
    if (png_ptr == NULL)
       return;
 
+   /* The flag setting here prevents the libpng dynamic selection of strategy.
+    */
    png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_STRATEGY;
    png_ptr->zlib_strategy = strategy;
 }
@@ -1431,80 +1413,82 @@ png_set_compression_strategy(png_structp png_ptr, int strategy)
  * smaller value of window_bits if it can do so safely.
  */
 void PNGAPI
-png_set_compression_window_bits(png_structp png_ptr, int window_bits)
+png_set_compression_window_bits(png_structrp png_ptr, int window_bits)
 {
    if (png_ptr == NULL)
       return;
 
+   /* Prior to 1.6.0 this would warn but then set the window_bits value. This
+    * meant that negative window bits values could be selected that would cause
+    * libpng to write a non-standard PNG file with raw deflate or gzip
+    * compressed IDAT or ancillary chunks.  Such files can be read and there is
+    * no warning on read, so this seems like a very bad idea.
+    */
    if (window_bits > 15)
+   {
       png_warning(png_ptr, "Only compression windows <= 32k supported by PNG");
+      window_bits = 15;
+   }
 
    else if (window_bits < 8)
+   {
       png_warning(png_ptr, "Only compression windows >= 256 supported by PNG");
+      window_bits = 8;
+   }
 
-#ifndef WBITS_8_OK
-   /* Avoid libpng bug with 256-byte windows */
-   if (window_bits == 8)
-      {
-        png_warning(png_ptr, "Compression window is being reset to 512");
-        window_bits = 9;
-      }
-
-#endif
-   png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS;
    png_ptr->zlib_window_bits = window_bits;
 }
 
 void PNGAPI
-png_set_compression_method(png_structp png_ptr, int method)
+png_set_compression_method(png_structrp png_ptr, int method)
 {
    png_debug(1, "in png_set_compression_method");
 
    if (png_ptr == NULL)
       return;
 
+   /* This would produce an invalid PNG file if it worked, but it doesn't and
+    * deflate will fault it, so it is harmless to just warn here.
+    */
    if (method != 8)
       png_warning(png_ptr, "Only compression method 8 is supported by PNG");
 
-   png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_METHOD;
    png_ptr->zlib_method = method;
 }
+#endif /* WRITE_CUSTOMIZE_COMPRESSION */
 
 /* The following were added to libpng-1.5.4 */
 #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
 void PNGAPI
-png_set_text_compression_level(png_structp png_ptr, int level)
+png_set_text_compression_level(png_structrp png_ptr, int level)
 {
    png_debug(1, "in png_set_text_compression_level");
 
    if (png_ptr == NULL)
       return;
 
-   png_ptr->flags |= PNG_FLAG_ZTXT_CUSTOM_LEVEL;
    png_ptr->zlib_text_level = level;
 }
 
 void PNGAPI
-png_set_text_compression_mem_level(png_structp png_ptr, int mem_level)
+png_set_text_compression_mem_level(png_structrp png_ptr, int mem_level)
 {
    png_debug(1, "in png_set_text_compression_mem_level");
 
    if (png_ptr == NULL)
       return;
 
-   png_ptr->flags |= PNG_FLAG_ZTXT_CUSTOM_MEM_LEVEL;
    png_ptr->zlib_text_mem_level = mem_level;
 }
 
 void PNGAPI
-png_set_text_compression_strategy(png_structp png_ptr, int strategy)
+png_set_text_compression_strategy(png_structrp png_ptr, int strategy)
 {
    png_debug(1, "in png_set_text_compression_strategy");
 
    if (png_ptr == NULL)
       return;
 
-   png_ptr->flags |= PNG_FLAG_ZTXT_CUSTOM_STRATEGY;
    png_ptr->zlib_text_strategy = strategy;
 }
 
@@ -1512,32 +1496,28 @@ png_set_text_compression_strategy(png_structp png_ptr, int strategy)
  * smaller value of window_bits if it can do so safely.
  */
 void PNGAPI
-png_set_text_compression_window_bits(png_structp png_ptr, int window_bits)
+png_set_text_compression_window_bits(png_structrp png_ptr, int window_bits)
 {
    if (png_ptr == NULL)
       return;
 
    if (window_bits > 15)
+   {
       png_warning(png_ptr, "Only compression windows <= 32k supported by PNG");
+      window_bits = 15;
+   }
 
    else if (window_bits < 8)
+   {
       png_warning(png_ptr, "Only compression windows >= 256 supported by PNG");
+      window_bits = 8;
+   }
 
-#ifndef WBITS_8_OK
-   /* Avoid libpng bug with 256-byte windows */
-   if (window_bits == 8)
-      {
-        png_warning(png_ptr, "Text compression window is being reset to 512");
-        window_bits = 9;
-      }
-
-#endif
-   png_ptr->flags |= PNG_FLAG_ZTXT_CUSTOM_WINDOW_BITS;
    png_ptr->zlib_text_window_bits = window_bits;
 }
 
 void PNGAPI
-png_set_text_compression_method(png_structp png_ptr, int method)
+png_set_text_compression_method(png_structrp png_ptr, int method)
 {
    png_debug(1, "in png_set_text_compression_method");
 
@@ -1547,14 +1527,13 @@ png_set_text_compression_method(png_structp png_ptr, int method)
    if (method != 8)
       png_warning(png_ptr, "Only compression method 8 is supported by PNG");
 
-   png_ptr->flags |= PNG_FLAG_ZTXT_CUSTOM_METHOD;
    png_ptr->zlib_text_method = method;
 }
-#endif /* PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED */
+#endif /* WRITE_CUSTOMIZE_ZTXT_COMPRESSION */
 /* end of API added to libpng-1.5.4 */
 
 void PNGAPI
-png_set_write_status_fn(png_structp png_ptr, png_write_status_ptr write_row_fn)
+png_set_write_status_fn(png_structrp png_ptr, png_write_status_ptr write_row_fn)
 {
    if (png_ptr == NULL)
       return;
@@ -1564,7 +1543,7 @@ png_set_write_status_fn(png_structp png_ptr, png_write_status_ptr write_row_fn)
 
 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
 void PNGAPI
-png_set_write_user_transform_fn(png_structp png_ptr, png_user_transform_ptr
+png_set_write_user_transform_fn(png_structrp png_ptr, png_user_transform_ptr
     write_user_transform_fn)
 {
    png_debug(1, "in png_set_write_user_transform_fn");
@@ -1580,88 +1559,901 @@ png_set_write_user_transform_fn(png_structp png_ptr, png_user_transform_ptr
 
 #ifdef PNG_INFO_IMAGE_SUPPORTED
 void PNGAPI
-png_write_png(png_structp png_ptr, png_infop info_ptr,
+png_write_png(png_structrp png_ptr, png_inforp info_ptr,
     int transforms, voidp params)
 {
    if (png_ptr == NULL || info_ptr == NULL)
       return;
 
+   if ((info_ptr->valid & PNG_INFO_IDAT) == 0)
+   {
+      png_app_error(png_ptr, "no rows for png_write_image to write");
+      return;
+   }
+
    /* Write the file header information. */
    png_write_info(png_ptr, info_ptr);
 
    /* ------ these transformations don't touch the info structure ------- */
 
-#ifdef PNG_WRITE_INVERT_SUPPORTED
    /* Invert monochrome pixels */
-   if (transforms & PNG_TRANSFORM_INVERT_MONO)
+   if ((transforms & PNG_TRANSFORM_INVERT_MONO) != 0)
+#ifdef PNG_WRITE_INVERT_SUPPORTED
       png_set_invert_mono(png_ptr);
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported");
 #endif
 
-#ifdef PNG_WRITE_SHIFT_SUPPORTED
    /* Shift the pixels up to a legal bit depth and fill in
     * as appropriate to correctly scale the image.
     */
-   if ((transforms & PNG_TRANSFORM_SHIFT)
-       && (info_ptr->valid & PNG_INFO_sBIT))
-      png_set_shift(png_ptr, &info_ptr->sig_bit);
+   if ((transforms & PNG_TRANSFORM_SHIFT) != 0)
+#ifdef PNG_WRITE_SHIFT_SUPPORTED
+      if ((info_ptr->valid & PNG_INFO_sBIT) != 0)
+         png_set_shift(png_ptr, &info_ptr->sig_bit);
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported");
 #endif
 
-#ifdef PNG_WRITE_PACK_SUPPORTED
    /* Pack pixels into bytes */
-   if (transforms & PNG_TRANSFORM_PACKING)
-       png_set_packing(png_ptr);
+   if ((transforms & PNG_TRANSFORM_PACKING) != 0)
+#ifdef PNG_WRITE_PACK_SUPPORTED
+      png_set_packing(png_ptr);
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported");
 #endif
 
-#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
    /* Swap location of alpha bytes from ARGB to RGBA */
-   if (transforms & PNG_TRANSFORM_SWAP_ALPHA)
+   if ((transforms & PNG_TRANSFORM_SWAP_ALPHA) != 0)
+#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
       png_set_swap_alpha(png_ptr);
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported");
 #endif
 
+   /* Remove a filler (X) from XRGB/RGBX/AG/GA into to convert it into
+    * RGB, note that the code expects the input color type to be G or RGB; no
+    * alpha channel.
+    */
+   if ((transforms & (PNG_TRANSFORM_STRIP_FILLER_AFTER|
+      PNG_TRANSFORM_STRIP_FILLER_BEFORE)) != 0)
+   {
 #ifdef PNG_WRITE_FILLER_SUPPORTED
-   /* Pack XRGB/RGBX/ARGB/RGBA into RGB (4 channels -> 3 channels) */
-   if (transforms & PNG_TRANSFORM_STRIP_FILLER_AFTER)
-      png_set_filler(png_ptr, 0, PNG_FILLER_AFTER);
+      if ((transforms & PNG_TRANSFORM_STRIP_FILLER_AFTER) != 0)
+      {
+         if ((transforms & PNG_TRANSFORM_STRIP_FILLER_BEFORE) != 0)
+            png_app_error(png_ptr,
+               "PNG_TRANSFORM_STRIP_FILLER: BEFORE+AFTER not supported");
+
+         /* Continue if ignored - this is the pre-1.6.10 behavior */
+         png_set_filler(png_ptr, 0, PNG_FILLER_AFTER);
+      }
 
-   else if (transforms & PNG_TRANSFORM_STRIP_FILLER_BEFORE)
-      png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
+      else if ((transforms & PNG_TRANSFORM_STRIP_FILLER_BEFORE) != 0)
+         png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_FILLER not supported");
 #endif
+   }
 
-#ifdef PNG_WRITE_BGR_SUPPORTED
    /* Flip BGR pixels to RGB */
-   if (transforms & PNG_TRANSFORM_BGR)
+   if ((transforms & PNG_TRANSFORM_BGR) != 0)
+#ifdef PNG_WRITE_BGR_SUPPORTED
       png_set_bgr(png_ptr);
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported");
 #endif
 
-#ifdef PNG_WRITE_SWAP_SUPPORTED
    /* Swap bytes of 16-bit files to most significant byte first */
-   if (transforms & PNG_TRANSFORM_SWAP_ENDIAN)
+   if ((transforms & PNG_TRANSFORM_SWAP_ENDIAN) != 0)
+#ifdef PNG_WRITE_SWAP_SUPPORTED
       png_set_swap(png_ptr);
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported");
 #endif
 
-#ifdef PNG_WRITE_PACKSWAP_SUPPORTED
    /* Swap bits of 1, 2, 4 bit packed pixel formats */
-   if (transforms & PNG_TRANSFORM_PACKSWAP)
+   if ((transforms & PNG_TRANSFORM_PACKSWAP) != 0)
+#ifdef PNG_WRITE_PACKSWAP_SUPPORTED
       png_set_packswap(png_ptr);
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported");
 #endif
 
-#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
    /* Invert the alpha channel from opacity to transparency */
-   if (transforms & PNG_TRANSFORM_INVERT_ALPHA)
+   if ((transforms & PNG_TRANSFORM_INVERT_ALPHA) != 0)
+#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
       png_set_invert_alpha(png_ptr);
+#else
+      png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported");
 #endif
 
    /* ----------------------- end of transformations ------------------- */
 
    /* Write the bits */
-   if (info_ptr->valid & PNG_INFO_IDAT)
-       png_write_image(png_ptr, info_ptr->row_pointers);
+   png_write_image(png_ptr, info_ptr->row_pointers);
 
    /* It is REQUIRED to call this to finish writing the rest of the file */
    png_write_end(png_ptr, info_ptr);
 
-   PNG_UNUSED(transforms)   /* Quiet compiler warnings */
    PNG_UNUSED(params)
 }
 #endif
-#endif /* PNG_WRITE_SUPPORTED */
+
+
+#ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
+#ifdef PNG_STDIO_SUPPORTED /* currently required for png_image_write_* */
+/* Initialize the write structure - general purpose utility. */
+static int
+png_image_write_init(png_imagep image)
+{
+   png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, image,
+          png_safe_error, png_safe_warning);
+
+   if (png_ptr != NULL)
+   {
+      png_infop info_ptr = png_create_info_struct(png_ptr);
+
+      if (info_ptr != NULL)
+      {
+         png_controlp control = png_voidcast(png_controlp,
+            png_malloc_warn(png_ptr, (sizeof *control)));
+
+         if (control != NULL)
+         {
+            memset(control, 0, (sizeof *control));
+
+            control->png_ptr = png_ptr;
+            control->info_ptr = info_ptr;
+            control->for_write = 1;
+
+            image->opaque = control;
+            return 1;
+         }
+
+         /* Error clean up */
+         png_destroy_info_struct(png_ptr, &info_ptr);
+      }
+
+      png_destroy_write_struct(&png_ptr, NULL);
+   }
+
+   return png_image_error(image, "png_image_write_: out of memory");
+}
+
+/* Arguments to png_image_write_main: */
+typedef struct
+{
+   /* Arguments: */
+   png_imagep      image;
+   png_const_voidp buffer;
+   png_int_32      row_stride;
+   png_const_voidp colormap;
+   int             convert_to_8bit;
+   /* Local variables: */
+   png_const_voidp first_row;
+   ptrdiff_t       row_bytes;
+   png_voidp       local_row;
+} png_image_write_control;
+
+/* Write png_uint_16 input to a 16-bit PNG; the png_ptr has already been set to
+ * do any necessary byte swapping.  The component order is defined by the
+ * png_image format value.
+ */
+static int
+png_write_image_16bit(png_voidp argument)
+{
+   png_image_write_control *display = png_voidcast(png_image_write_control*,
+      argument);
+   png_imagep image = display->image;
+   png_structrp png_ptr = image->opaque->png_ptr;
+
+   png_const_uint_16p input_row = png_voidcast(png_const_uint_16p,
+      display->first_row);
+   png_uint_16p output_row = png_voidcast(png_uint_16p, display->local_row);
+   png_uint_16p row_end;
+   const int channels = (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1;
+   int aindex = 0;
+   png_uint_32 y = image->height;
+
+   if ((image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
+   {
+#     ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
+         if ((image->format & PNG_FORMAT_FLAG_AFIRST) != 0)
+         {
+            aindex = -1;
+            ++input_row; /* To point to the first component */
+            ++output_row;
+         }
+
+         else
+#     endif
+         aindex = channels;
+   }
+
+   else
+      png_error(png_ptr, "png_write_image: internal call error");
+
+   /* Work out the output row end and count over this, note that the increment
+    * above to 'row' means that row_end can actually be beyond the end of the
+    * row; this is correct.
+    */
+   row_end = output_row + image->width * (channels+1);
+
+   while (y-- > 0)
+   {
+      png_const_uint_16p in_ptr = input_row;
+      png_uint_16p out_ptr = output_row;
+
+      while (out_ptr < row_end)
+      {
+         const png_uint_16 alpha = in_ptr[aindex];
+         png_uint_32 reciprocal = 0;
+         int c;
+
+         out_ptr[aindex] = alpha;
+
+         /* Calculate a reciprocal.  The correct calculation is simply
+          * component/alpha*65535 << 15. (I.e. 15 bits of precision); this
+          * allows correct rounding by adding .5 before the shift.  'reciprocal'
+          * is only initialized when required.
+          */
+         if (alpha > 0 && alpha < 65535)
+            reciprocal = ((0xffff<<15)+(alpha>>1))/alpha;
+
+         c = channels;
+         do /* always at least one channel */
+         {
+            png_uint_16 component = *in_ptr++;
+
+            /* The following gives 65535 for an alpha of 0, which is fine,
+             * otherwise if 0/0 is represented as some other value there is more
+             * likely to be a discontinuity which will probably damage
+             * compression when moving from a fully transparent area to a
+             * nearly transparent one.  (The assumption here is that opaque
+             * areas tend not to be 0 intensity.)
+             */
+            if (component >= alpha)
+               component = 65535;
+
+            /* component<alpha, so component/alpha is less than one and
+             * component*reciprocal is less than 2^31.
+             */
+            else if (component > 0 && alpha < 65535)
+            {
+               png_uint_32 calc = component * reciprocal;
+               calc += 16384; /* round to nearest */
+               component = (png_uint_16)(calc >> 15);
+            }
+
+            *out_ptr++ = component;
+         }
+         while (--c > 0);
+
+         /* Skip to next component (skip the intervening alpha channel) */
+         ++in_ptr;
+         ++out_ptr;
+      }
+
+      png_write_row(png_ptr, png_voidcast(png_const_bytep, display->local_row));
+      input_row += display->row_bytes/(sizeof (png_uint_16));
+   }
+
+   return 1;
+}
+
+/* Given 16-bit input (1 to 4 channels) write 8-bit output.  If an alpha channel
+ * is present it must be removed from the components, the components are then
+ * written in sRGB encoding.  No components are added or removed.
+ *
+ * Calculate an alpha reciprocal to reverse pre-multiplication.  As above the
+ * calculation can be done to 15 bits of accuracy; however, the output needs to
+ * be scaled in the range 0..255*65535, so include that scaling here.
+ */
+#define UNP_RECIPROCAL(alpha) ((((0xffff*0xff)<<7)+(alpha>>1))/alpha)
+
+static png_byte
+png_unpremultiply(png_uint_32 component, png_uint_32 alpha,
+   png_uint_32 reciprocal/*from the above macro*/)
+{
+   /* The following gives 1.0 for an alpha of 0, which is fine, otherwise if 0/0
+    * is represented as some other value there is more likely to be a
+    * discontinuity which will probably damage compression when moving from a
+    * fully transparent area to a nearly transparent one.  (The assumption here
+    * is that opaque areas tend not to be 0 intensity.)
+    *
+    * There is a rounding problem here; if alpha is less than 128 it will end up
+    * as 0 when scaled to 8 bits.  To avoid introducing spurious colors into the
+    * output change for this too.
+    */
+   if (component >= alpha || alpha < 128)
+      return 255;
+
+   /* component<alpha, so component/alpha is less than one and
+    * component*reciprocal is less than 2^31.
+    */
+   else if (component > 0)
+   {
+      /* The test is that alpha/257 (rounded) is less than 255, the first value
+       * that becomes 255 is 65407.
+       * NOTE: this must agree with the PNG_DIV257 macro (which must, therefore,
+       * be exact!)  [Could also test reciprocal != 0]
+       */
+      if (alpha < 65407)
+      {
+         component *= reciprocal;
+         component += 64; /* round to nearest */
+         component >>= 7;
+      }
+
+      else
+         component *= 255;
+
+      /* Convert the component to sRGB. */
+      return (png_byte)PNG_sRGB_FROM_LINEAR(component);
+   }
+
+   else
+      return 0;
+}
+
+static int
+png_write_image_8bit(png_voidp argument)
+{
+   png_image_write_control *display = png_voidcast(png_image_write_control*,
+      argument);
+   png_imagep image = display->image;
+   png_structrp png_ptr = image->opaque->png_ptr;
+
+   png_const_uint_16p input_row = png_voidcast(png_const_uint_16p,
+      display->first_row);
+   png_bytep output_row = png_voidcast(png_bytep, display->local_row);
+   png_uint_32 y = image->height;
+   const int channels = (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1;
+
+   if ((image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
+   {
+      png_bytep row_end;
+      int aindex;
+
+#     ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
+         if ((image->format & PNG_FORMAT_FLAG_AFIRST) != 0)
+         {
+            aindex = -1;
+            ++input_row; /* To point to the first component */
+            ++output_row;
+         }
+
+         else
+#     endif
+         aindex = channels;
+
+      /* Use row_end in place of a loop counter: */
+      row_end = output_row + image->width * (channels+1);
+
+      while (y-- > 0)
+      {
+         png_const_uint_16p in_ptr = input_row;
+         png_bytep out_ptr = output_row;
+
+         while (out_ptr < row_end)
+         {
+            png_uint_16 alpha = in_ptr[aindex];
+            png_byte alphabyte = (png_byte)PNG_DIV257(alpha);
+            png_uint_32 reciprocal = 0;
+            int c;
+
+            /* Scale and write the alpha channel. */
+            out_ptr[aindex] = alphabyte;
+
+            if (alphabyte > 0 && alphabyte < 255)
+               reciprocal = UNP_RECIPROCAL(alpha);
+
+            c = channels;
+            do /* always at least one channel */
+               *out_ptr++ = png_unpremultiply(*in_ptr++, alpha, reciprocal);
+            while (--c > 0);
+
+            /* Skip to next component (skip the intervening alpha channel) */
+            ++in_ptr;
+            ++out_ptr;
+         } /* while out_ptr < row_end */
+
+         png_write_row(png_ptr, png_voidcast(png_const_bytep,
+            display->local_row));
+         input_row += display->row_bytes/(sizeof (png_uint_16));
+      } /* while y */
+   }
+
+   else
+   {
+      /* No alpha channel, so the row_end really is the end of the row and it
+       * is sufficient to loop over the components one by one.
+       */
+      png_bytep row_end = output_row + image->width * channels;
+
+      while (y-- > 0)
+      {
+         png_const_uint_16p in_ptr = input_row;
+         png_bytep out_ptr = output_row;
+
+         while (out_ptr < row_end)
+         {
+            png_uint_32 component = *in_ptr++;
+
+            component *= 255;
+            *out_ptr++ = (png_byte)PNG_sRGB_FROM_LINEAR(component);
+         }
+
+         png_write_row(png_ptr, output_row);
+         input_row += display->row_bytes/(sizeof (png_uint_16));
+      }
+   }
+
+   return 1;
+}
+
+static void
+png_image_set_PLTE(png_image_write_control *display)
+{
+   const png_imagep image = display->image;
+   const void *cmap = display->colormap;
+   const int entries = image->colormap_entries > 256 ? 256 :
+      (int)image->colormap_entries;
+
+   /* NOTE: the caller must check for cmap != NULL and entries != 0 */
+   const png_uint_32 format = image->format;
+   const int channels = PNG_IMAGE_SAMPLE_CHANNELS(format);
+
+#  if defined(PNG_FORMAT_BGR_SUPPORTED) &&\
+      defined(PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED)
+      const int afirst = (format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
+         (format & PNG_FORMAT_FLAG_ALPHA) != 0;
+#  else
+#     define afirst 0
+#  endif
+
+#  ifdef PNG_FORMAT_BGR_SUPPORTED
+      const int bgr = (format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0;
+#  else
+#     define bgr 0
+#  endif
+
+   int i, num_trans;
+   png_color palette[256];
+   png_byte tRNS[256];
+
+   memset(tRNS, 255, (sizeof tRNS));
+   memset(palette, 0, (sizeof palette));
+
+   for (i=num_trans=0; i<entries; ++i)
+   {
+      /* This gets automatically converted to sRGB with reversal of the
+       * pre-multiplication if the color-map has an alpha channel.
+       */
+      if ((format & PNG_FORMAT_FLAG_LINEAR) != 0)
+      {
+         png_const_uint_16p entry = png_voidcast(png_const_uint_16p, cmap);
+
+         entry += i * channels;
+
+         if ((channels & 1) != 0) /* no alpha */
+         {
+            if (channels >= 3) /* RGB */
+            {
+               palette[i].blue = (png_byte)PNG_sRGB_FROM_LINEAR(255 *
+                  entry[(2 ^ bgr)]);
+               palette[i].green = (png_byte)PNG_sRGB_FROM_LINEAR(255 *
+                  entry[1]);
+               palette[i].red = (png_byte)PNG_sRGB_FROM_LINEAR(255 *
+                  entry[bgr]);
+            }
+
+            else /* Gray */
+               palette[i].blue = palette[i].red = palette[i].green =
+                  (png_byte)PNG_sRGB_FROM_LINEAR(255 * *entry);
+         }
+
+         else /* alpha */
+         {
+            png_uint_16 alpha = entry[afirst ? 0 : channels-1];
+            png_byte alphabyte = (png_byte)PNG_DIV257(alpha);
+            png_uint_32 reciprocal = 0;
+
+            /* Calculate a reciprocal, as in the png_write_image_8bit code above
+             * this is designed to produce a value scaled to 255*65535 when
+             * divided by 128 (i.e. asr 7).
+             */
+            if (alphabyte > 0 && alphabyte < 255)
+               reciprocal = (((0xffff*0xff)<<7)+(alpha>>1))/alpha;
+
+            tRNS[i] = alphabyte;
+            if (alphabyte < 255)
+               num_trans = i+1;
+
+            if (channels >= 3) /* RGB */
+            {
+               palette[i].blue = png_unpremultiply(entry[afirst + (2 ^ bgr)],
+                  alpha, reciprocal);
+               palette[i].green = png_unpremultiply(entry[afirst + 1], alpha,
+                  reciprocal);
+               palette[i].red = png_unpremultiply(entry[afirst + bgr], alpha,
+                  reciprocal);
+            }
+
+            else /* gray */
+               palette[i].blue = palette[i].red = palette[i].green =
+                  png_unpremultiply(entry[afirst], alpha, reciprocal);
+         }
+      }
+
+      else /* Color-map has sRGB values */
+      {
+         png_const_bytep entry = png_voidcast(png_const_bytep, cmap);
+
+         entry += i * channels;
+
+         switch (channels)
+         {
+            case 4:
+               tRNS[i] = entry[afirst ? 0 : 3];
+               if (tRNS[i] < 255)
+                  num_trans = i+1;
+               /* FALL THROUGH */
+            case 3:
+               palette[i].blue = entry[afirst + (2 ^ bgr)];
+               palette[i].green = entry[afirst + 1];
+               palette[i].red = entry[afirst + bgr];
+               break;
+
+            case 2:
+               tRNS[i] = entry[1 ^ afirst];
+               if (tRNS[i] < 255)
+                  num_trans = i+1;
+               /* FALL THROUGH */
+            case 1:
+               palette[i].blue = palette[i].red = palette[i].green =
+                  entry[afirst];
+               break;
+
+            default:
+               break;
+         }
+      }
+   }
+
+#  ifdef afirst
+#     undef afirst
+#  endif
+#  ifdef bgr
+#     undef bgr
+#  endif
+
+   png_set_PLTE(image->opaque->png_ptr, image->opaque->info_ptr, palette,
+      entries);
+
+   if (num_trans > 0)
+      png_set_tRNS(image->opaque->png_ptr, image->opaque->info_ptr, tRNS,
+         num_trans, NULL);
+
+   image->colormap_entries = entries;
+}
+
+static int
+png_image_write_main(png_voidp argument)
+{
+   png_image_write_control *display = png_voidcast(png_image_write_control*,
+      argument);
+   png_imagep image = display->image;
+   png_structrp png_ptr = image->opaque->png_ptr;
+   png_inforp info_ptr = image->opaque->info_ptr;
+   png_uint_32 format = image->format;
+
+   /* The following four ints are actually booleans */
+   int colormap = (format & PNG_FORMAT_FLAG_COLORMAP);
+   int linear = !colormap && (format & PNG_FORMAT_FLAG_LINEAR); /* input */
+   int alpha = !colormap && (format & PNG_FORMAT_FLAG_ALPHA);
+   int write_16bit = linear && !colormap && (display->convert_to_8bit == 0);
+
+#  ifdef PNG_BENIGN_ERRORS_SUPPORTED
+      /* Make sure we error out on any bad situation */
+      png_set_benign_errors(png_ptr, 0/*error*/);
+#  endif
+
+   /* Default the 'row_stride' parameter if required. */
+   if (display->row_stride == 0)
+      display->row_stride = PNG_IMAGE_ROW_STRIDE(*image);
+
+   /* Set the required transforms then write the rows in the correct order. */
+   if ((format & PNG_FORMAT_FLAG_COLORMAP) != 0)
+   {
+      if (display->colormap != NULL && image->colormap_entries > 0)
+      {
+         png_uint_32 entries = image->colormap_entries;
+
+         png_set_IHDR(png_ptr, info_ptr, image->width, image->height,
+            entries > 16 ? 8 : (entries > 4 ? 4 : (entries > 2 ? 2 : 1)),
+            PNG_COLOR_TYPE_PALETTE, PNG_INTERLACE_NONE,
+            PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+
+         png_image_set_PLTE(display);
+      }
+
+      else
+         png_error(image->opaque->png_ptr,
+            "no color-map for color-mapped image");
+   }
+
+   else
+      png_set_IHDR(png_ptr, info_ptr, image->width, image->height,
+         write_16bit ? 16 : 8,
+         ((format & PNG_FORMAT_FLAG_COLOR) ? PNG_COLOR_MASK_COLOR : 0) +
+         ((format & PNG_FORMAT_FLAG_ALPHA) ? PNG_COLOR_MASK_ALPHA : 0),
+         PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+
+   /* Counter-intuitively the data transformations must be called *after*
+    * png_write_info, not before as in the read code, but the 'set' functions
+    * must still be called before.  Just set the color space information, never
+    * write an interlaced image.
+    */
+
+   if (write_16bit != 0)
+   {
+      /* The gamma here is 1.0 (linear) and the cHRM chunk matches sRGB. */
+      png_set_gAMA_fixed(png_ptr, info_ptr, PNG_GAMMA_LINEAR);
+
+      if ((image->flags & PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB) == 0)
+         png_set_cHRM_fixed(png_ptr, info_ptr,
+            /* color      x       y */
+            /* white */ 31270, 32900,
+            /* red   */ 64000, 33000,
+            /* green */ 30000, 60000,
+            /* blue  */ 15000,  6000
+         );
+   }
+
+   else if ((image->flags & PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB) == 0)
+      png_set_sRGB(png_ptr, info_ptr, PNG_sRGB_INTENT_PERCEPTUAL);
+
+   /* Else writing an 8-bit file and the *colors* aren't sRGB, but the 8-bit
+    * space must still be gamma encoded.
+    */
+   else
+      png_set_gAMA_fixed(png_ptr, info_ptr, PNG_GAMMA_sRGB_INVERSE);
+
+   /* Write the file header. */
+   png_write_info(png_ptr, info_ptr);
+
+   /* Now set up the data transformations (*after* the header is written),
+    * remove the handled transformations from the 'format' flags for checking.
+    *
+    * First check for a little endian system if writing 16 bit files.
+    */
+   if (write_16bit != 0)
+   {
+      PNG_CONST png_uint_16 le = 0x0001;
+
+      if ((*(png_const_bytep) & le) != 0)
+         png_set_swap(png_ptr);
+   }
+
+#  ifdef PNG_SIMPLIFIED_WRITE_BGR_SUPPORTED
+      if ((format & PNG_FORMAT_FLAG_BGR) != 0)
+      {
+         if (colormap == 0 && (format & PNG_FORMAT_FLAG_COLOR) != 0)
+            png_set_bgr(png_ptr);
+         format &= ~PNG_FORMAT_FLAG_BGR;
+      }
+#  endif
+
+#  ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
+      if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
+      {
+         if (colormap == 0 && (format & PNG_FORMAT_FLAG_ALPHA) != 0)
+            png_set_swap_alpha(png_ptr);
+         format &= ~PNG_FORMAT_FLAG_AFIRST;
+      }
+#  endif
+
+   /* If there are 16 or fewer color-map entries we wrote a lower bit depth
+    * above, but the application data is still byte packed.
+    */
+   if (colormap != 0 && image->colormap_entries <= 16)
+      png_set_packing(png_ptr);
+
+   /* That should have handled all (both) the transforms. */
+   if ((format & ~(png_uint_32)(PNG_FORMAT_FLAG_COLOR | PNG_FORMAT_FLAG_LINEAR |
+         PNG_FORMAT_FLAG_ALPHA | PNG_FORMAT_FLAG_COLORMAP)) != 0)
+      png_error(png_ptr, "png_write_image: unsupported transformation");
+
+   {
+      png_const_bytep row = png_voidcast(png_const_bytep, display->buffer);
+      ptrdiff_t row_bytes = display->row_stride;
+
+      if (linear != 0)
+         row_bytes *= (sizeof (png_uint_16));
+
+      if (row_bytes < 0)
+         row += (image->height-1) * (-row_bytes);
+
+      display->first_row = row;
+      display->row_bytes = row_bytes;
+   }
+
+   /* Apply 'fast' options if the flag is set. */
+   if ((image->flags & PNG_IMAGE_FLAG_FAST) != 0)
+   {
+      png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE, PNG_NO_FILTERS);
+      /* NOTE: determined by experiment using pngstest, this reflects some
+       * balance between the time to write the image once and the time to read
+       * it about 50 times.  The speed-up in pngstest was about 10-20% of the
+       * total (user) time on a heavily loaded system.
+       */
+#ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED
+      png_set_compression_level(png_ptr, 3);
+#endif
+   }
+
+   /* Check for the cases that currently require a pre-transform on the row
+    * before it is written.  This only applies when the input is 16-bit and
+    * either there is an alpha channel or it is converted to 8-bit.
+    */
+   if ((linear != 0 && alpha != 0 ) ||
+       (colormap == 0 && display->convert_to_8bit != 0))
+   {
+      png_bytep row = png_voidcast(png_bytep, png_malloc(png_ptr,
+         png_get_rowbytes(png_ptr, info_ptr)));
+      int result;
+
+      display->local_row = row;
+      if (write_16bit != 0)
+         result = png_safe_execute(image, png_write_image_16bit, display);
+      else
+         result = png_safe_execute(image, png_write_image_8bit, display);
+      display->local_row = NULL;
+
+      png_free(png_ptr, row);
+
+      /* Skip the 'write_end' on error: */
+      if (result == 0)
+         return 0;
+   }
+
+   /* Otherwise this is the case where the input is in a format currently
+    * supported by the rest of the libpng write code; call it directly.
+    */
+   else
+   {
+      png_const_bytep row = png_voidcast(png_const_bytep, display->first_row);
+      ptrdiff_t row_bytes = display->row_bytes;
+      png_uint_32 y = image->height;
+
+      while (y-- > 0)
+      {
+         png_write_row(png_ptr, row);
+         row += row_bytes;
+      }
+   }
+
+   png_write_end(png_ptr, info_ptr);
+   return 1;
+}
+
+int PNGAPI
+png_image_write_to_stdio(png_imagep image, FILE *file, int convert_to_8bit,
+   const void *buffer, png_int_32 row_stride, const void *colormap)
+{
+   /* Write the image to the given (FILE*). */
+   if (image != NULL && image->version == PNG_IMAGE_VERSION)
+   {
+      if (file != NULL)
+      {
+         if (png_image_write_init(image) != 0)
+         {
+            png_image_write_control display;
+            int result;
+
+            /* This is slightly evil, but png_init_io doesn't do anything other
+             * than this and we haven't changed the standard IO functions so
+             * this saves a 'safe' function.
+             */
+            image->opaque->png_ptr->io_ptr = file;
+
+            memset(&display, 0, (sizeof display));
+            display.image = image;
+            display.buffer = buffer;
+            display.row_stride = row_stride;
+            display.colormap = colormap;
+            display.convert_to_8bit = convert_to_8bit;
+
+            result = png_safe_execute(image, png_image_write_main, &display);
+            png_image_free(image);
+            return result;
+         }
+
+         else
+            return 0;
+      }
+
+      else
+         return png_image_error(image,
+            "png_image_write_to_stdio: invalid argument");
+   }
+
+   else if (image != NULL)
+      return png_image_error(image,
+         "png_image_write_to_stdio: incorrect PNG_IMAGE_VERSION");
+
+   else
+      return 0;
+}
+
+int PNGAPI
+png_image_write_to_file(png_imagep image, const char *file_name,
+   int convert_to_8bit, const void *buffer, png_int_32 row_stride,
+   const void *colormap)
+{
+   /* Write the image to the named file. */
+   if (image != NULL && image->version == PNG_IMAGE_VERSION)
+   {
+      if (file_name != NULL)
+      {
+         FILE *fp = fopen(file_name, "wb");
+
+         if (fp != NULL)
+         {
+            if (png_image_write_to_stdio(image, fp, convert_to_8bit, buffer,
+               row_stride, colormap) != 0)
+            {
+               int error; /* from fflush/fclose */
+
+               /* Make sure the file is flushed correctly. */
+               if (fflush(fp) == 0 && ferror(fp) == 0)
+               {
+                  if (fclose(fp) == 0)
+                     return 1;
+
+                  error = errno; /* from fclose */
+               }
+
+               else
+               {
+                  error = errno; /* from fflush or ferror */
+                  (void)fclose(fp);
+               }
+
+               (void)remove(file_name);
+               /* The image has already been cleaned up; this is just used to
+                * set the error (because the original write succeeded).
+                */
+               return png_image_error(image, strerror(error));
+            }
+
+            else
+            {
+               /* Clean up: just the opened file. */
+               (void)fclose(fp);
+               (void)remove(file_name);
+               return 0;
+            }
+         }
+
+         else
+            return png_image_error(image, strerror(errno));
+      }
+
+      else
+         return png_image_error(image,
+            "png_image_write_to_file: invalid argument");
+   }
+
+   else if (image != NULL)
+      return png_image_error(image,
+         "png_image_write_to_file: incorrect PNG_IMAGE_VERSION");
+
+   else
+      return 0;
+}
+#endif /* STDIO */
+#endif /* SIMPLIFIED_WRITE */
+#endif /* WRITE */
diff --git a/src/3rdparty/libpng/pngwtran.c b/src/3rdparty/libpng/pngwtran.c
index 96608ef..db82e27 100644
--- a/src/3rdparty/libpng/pngwtran.c
+++ b/src/3rdparty/libpng/pngwtran.c
@@ -1,8 +1,8 @@
 
 /* pngwtran.c - transforms the data in a row for PNG writers
  *
- * Last changed in libpng 1.5.6 [November 3, 2011]
- * Copyright (c) 1998-2011 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.17 [March 26, 2015]
+ * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
@@ -14,90 +14,14 @@
 #include "pngpriv.h"
 
 #ifdef PNG_WRITE_SUPPORTED
-
 #ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
-/* Transform the data according to the user's wishes.  The order of
- * transformations is significant.
- */
-void /* PRIVATE */
-png_do_write_transformations(png_structp png_ptr, png_row_infop row_info)
-{
-   png_debug(1, "in png_do_write_transformations");
-
-   if (png_ptr == NULL)
-      return;
-
-#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
-   if (png_ptr->transformations & PNG_USER_TRANSFORM)
-      if (png_ptr->write_user_transform_fn != NULL)
-         (*(png_ptr->write_user_transform_fn)) /* User write transform
-                                                 function */
-             (png_ptr,  /* png_ptr */
-             row_info,  /* row_info: */
-                /*  png_uint_32 width;       width of row */
-                /*  png_size_t rowbytes;     number of bytes in row */
-                /*  png_byte color_type;     color type of pixels */
-                /*  png_byte bit_depth;      bit depth of samples */
-                /*  png_byte channels;       number of channels (1-4) */
-                /*  png_byte pixel_depth;    bits per pixel (depth*channels) */
-             png_ptr->row_buf + 1);      /* start of pixel data for row */
-#endif
-
-#ifdef PNG_WRITE_FILLER_SUPPORTED
-   if (png_ptr->transformations & PNG_FILLER)
-      png_do_strip_channel(row_info, png_ptr->row_buf + 1,
-         !(png_ptr->flags & PNG_FLAG_FILLER_AFTER));
-#endif
-
-#ifdef PNG_WRITE_PACKSWAP_SUPPORTED
-   if (png_ptr->transformations & PNG_PACKSWAP)
-      png_do_packswap(row_info, png_ptr->row_buf + 1);
-#endif
-
-#ifdef PNG_WRITE_PACK_SUPPORTED
-   if (png_ptr->transformations & PNG_PACK)
-      png_do_pack(row_info, png_ptr->row_buf + 1,
-          (png_uint_32)png_ptr->bit_depth);
-#endif
-
-#ifdef PNG_WRITE_SWAP_SUPPORTED
-   if (png_ptr->transformations & PNG_SWAP_BYTES)
-      png_do_swap(row_info, png_ptr->row_buf + 1);
-#endif
-
-#ifdef PNG_WRITE_SHIFT_SUPPORTED
-   if (png_ptr->transformations & PNG_SHIFT)
-      png_do_shift(row_info, png_ptr->row_buf + 1,
-          &(png_ptr->shift));
-#endif
-
-#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
-   if (png_ptr->transformations & PNG_SWAP_ALPHA)
-      png_do_write_swap_alpha(row_info, png_ptr->row_buf + 1);
-#endif
-
-#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
-   if (png_ptr->transformations & PNG_INVERT_ALPHA)
-      png_do_write_invert_alpha(row_info, png_ptr->row_buf + 1);
-#endif
-
-#ifdef PNG_WRITE_BGR_SUPPORTED
-   if (png_ptr->transformations & PNG_BGR)
-      png_do_bgr(row_info, png_ptr->row_buf + 1);
-#endif
-
-#ifdef PNG_WRITE_INVERT_SUPPORTED
-   if (png_ptr->transformations & PNG_INVERT_MONO)
-      png_do_invert(row_info, png_ptr->row_buf + 1);
-#endif
-}
 
 #ifdef PNG_WRITE_PACK_SUPPORTED
 /* Pack pixels into bytes.  Pass the true bit depth in bit_depth.  The
  * row_info bit depth should be 8 (one pixel per byte).  The channels
  * should be 1 (this only happens on grayscale and paletted images).
  */
-void /* PRIVATE */
+static void
 png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
 {
    png_debug(1, "in png_do_pack");
@@ -242,7 +166,7 @@ png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
  * would pass 3 as bit_depth, and this routine would translate the
  * data to 0 to 15.
  */
-void /* PRIVATE */
+static void
 png_do_shift(png_row_infop row_info, png_bytep row,
     png_const_color_8p bit_depth)
 {
@@ -253,7 +177,7 @@ png_do_shift(png_row_infop row_info, png_bytep row,
       int shift_start[4], shift_dec[4];
       int channels = 0;
 
-      if (row_info->color_type & PNG_COLOR_MASK_COLOR)
+      if ((row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
       {
          shift_start[channels] = row_info->bit_depth - bit_depth->red;
          shift_dec[channels] = bit_depth->red;
@@ -275,7 +199,7 @@ png_do_shift(png_row_infop row_info, png_bytep row,
          channels++;
       }
 
-      if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
+      if ((row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
       {
          shift_start[channels] = row_info->bit_depth - bit_depth->alpha;
          shift_dec[channels] = bit_depth->alpha;
@@ -287,7 +211,7 @@ png_do_shift(png_row_infop row_info, png_bytep row,
       {
          png_bytep bp = row;
          png_size_t i;
-         png_byte mask;
+         unsigned int mask;
          png_size_t row_bytes = row_info->rowbytes;
 
          if (bit_depth->gray == 1 && row_info->bit_depth == 2)
@@ -301,20 +225,22 @@ png_do_shift(png_row_infop row_info, png_bytep row,
 
          for (i = 0; i < row_bytes; i++, bp++)
          {
-            png_uint_16 v;
             int j;
+            unsigned int v, out;
 
             v = *bp;
-            *bp = 0;
+            out = 0;
 
             for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])
             {
                if (j > 0)
-                  *bp |= (png_byte)((v << j) & 0xff);
+                  out |= v << j;
 
                else
-                  *bp |= (png_byte)((v >> (-j)) & mask);
+                  out |= (v >> (-j)) & mask;
             }
+
+            *bp = (png_byte)(out & 0xff);
          }
       }
 
@@ -327,21 +253,23 @@ png_do_shift(png_row_infop row_info, png_bytep row,
          for (i = 0; i < istop; i++, bp++)
          {
 
-            png_uint_16 v;
+            const unsigned int c = i%channels;
             int j;
-            int c = (int)(i%channels);
+            unsigned int v, out;
 
             v = *bp;
-            *bp = 0;
+            out = 0;
 
             for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
             {
                if (j > 0)
-                  *bp |= (png_byte)((v << j) & 0xff);
+                  out |= v << j;
 
                else
-                  *bp |= (png_byte)((v >> (-j)) & 0xff);
+                  out |= v >> (-j);
             }
+
+            *bp = (png_byte)(out & 0xff);
          }
       }
 
@@ -353,22 +281,22 @@ png_do_shift(png_row_infop row_info, png_bytep row,
 
          for (bp = row, i = 0; i < istop; i++)
          {
-            int c = (int)(i%channels);
-            png_uint_16 value, v;
+            const unsigned int c = i%channels;
             int j;
+            unsigned int value, v;
 
-            v = (png_uint_16)(((png_uint_16)(*bp) << 8) + *(bp + 1));
+            v = png_get_uint_16(bp);
             value = 0;
 
             for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
             {
                if (j > 0)
-                  value |= (png_uint_16)((v << j) & (png_uint_16)0xffff);
+                  value |= v << j;
 
                else
-                  value |= (png_uint_16)((v >> (-j)) & (png_uint_16)0xffff);
+                  value |= v >> (-j);
             }
-            *bp++ = (png_byte)(value >> 8);
+            *bp++ = (png_byte)((value >> 8) & 0xff);
             *bp++ = (png_byte)(value & 0xff);
          }
       }
@@ -377,7 +305,7 @@ png_do_shift(png_row_infop row_info, png_bytep row,
 #endif
 
 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
-void /* PRIVATE */
+static void
 png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
 {
    png_debug(1, "in png_do_write_swap_alpha");
@@ -425,7 +353,7 @@ png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
                *(dp++) = save[1];
             }
          }
-#endif /* PNG_WRITE_16BIT_SUPPORTED */
+#endif /* WRITE_16BIT */
       }
 
       else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
@@ -464,14 +392,14 @@ png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
                *(dp++) = save[1];
             }
          }
-#endif /* PNG_WRITE_16BIT_SUPPORTED */
+#endif /* WRITE_16BIT */
       }
    }
 }
 #endif
 
 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
-void /* PRIVATE */
+static void
 png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
 {
    png_debug(1, "in png_do_write_invert_alpha");
@@ -521,7 +449,7 @@ png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
                *(dp++) = (png_byte)(255 - *(sp++));
             }
          }
-#endif /* PNG_WRITE_16BIT_SUPPORTED */
+#endif /* WRITE_16BIT */
       }
 
       else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
@@ -559,75 +487,88 @@ png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
                *(dp++) = (png_byte)(255 - *(sp++));
             }
          }
-#endif /* PNG_WRITE_16BIT_SUPPORTED */
+#endif /* WRITE_16BIT */
       }
    }
 }
 #endif
-#endif /* PNG_WRITE_TRANSFORMS_SUPPORTED */
 
-#ifdef PNG_MNG_FEATURES_SUPPORTED
-/* Undoes intrapixel differencing  */
+/* Transform the data according to the user's wishes.  The order of
+ * transformations is significant.
+ */
 void /* PRIVATE */
-png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
+png_do_write_transformations(png_structrp png_ptr, png_row_infop row_info)
 {
-   png_debug(1, "in png_do_write_intrapixel");
+   png_debug(1, "in png_do_write_transformations");
 
-   if ((row_info->color_type & PNG_COLOR_MASK_COLOR))
-   {
-      int bytes_per_pixel;
-      png_uint_32 row_width = row_info->width;
-      if (row_info->bit_depth == 8)
-      {
-         png_bytep rp;
-         png_uint_32 i;
+   if (png_ptr == NULL)
+      return;
 
-         if (row_info->color_type == PNG_COLOR_TYPE_RGB)
-            bytes_per_pixel = 3;
+#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
+   if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
+      if (png_ptr->write_user_transform_fn != NULL)
+         (*(png_ptr->write_user_transform_fn)) /* User write transform
+                                                 function */
+             (png_ptr,  /* png_ptr */
+             row_info,  /* row_info: */
+                /*  png_uint_32 width;       width of row */
+                /*  png_size_t rowbytes;     number of bytes in row */
+                /*  png_byte color_type;     color type of pixels */
+                /*  png_byte bit_depth;      bit depth of samples */
+                /*  png_byte channels;       number of channels (1-4) */
+                /*  png_byte pixel_depth;    bits per pixel (depth*channels) */
+             png_ptr->row_buf + 1);      /* start of pixel data for row */
+#endif
 
-         else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
-            bytes_per_pixel = 4;
+#ifdef PNG_WRITE_FILLER_SUPPORTED
+   if ((png_ptr->transformations & PNG_FILLER) != 0)
+      png_do_strip_channel(row_info, png_ptr->row_buf + 1,
+         !(png_ptr->flags & PNG_FLAG_FILLER_AFTER));
+#endif
 
-         else
-            return;
+#ifdef PNG_WRITE_PACKSWAP_SUPPORTED
+   if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
+      png_do_packswap(row_info, png_ptr->row_buf + 1);
+#endif
 
-         for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
-         {
-            *(rp)     = (png_byte)((*rp       - *(rp + 1)) & 0xff);
-            *(rp + 2) = (png_byte)((*(rp + 2) - *(rp + 1)) & 0xff);
-         }
-      }
+#ifdef PNG_WRITE_PACK_SUPPORTED
+   if ((png_ptr->transformations & PNG_PACK) != 0)
+      png_do_pack(row_info, png_ptr->row_buf + 1,
+          (png_uint_32)png_ptr->bit_depth);
+#endif
 
-#ifdef PNG_WRITE_16BIT_SUPPORTED
-      else if (row_info->bit_depth == 16)
-      {
-         png_bytep rp;
-         png_uint_32 i;
+#ifdef PNG_WRITE_SWAP_SUPPORTED
+#  ifdef PNG_16BIT_SUPPORTED
+   if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
+      png_do_swap(row_info, png_ptr->row_buf + 1);
+#  endif
+#endif
+
+#ifdef PNG_WRITE_SHIFT_SUPPORTED
+   if ((png_ptr->transformations & PNG_SHIFT) != 0)
+      png_do_shift(row_info, png_ptr->row_buf + 1,
+          &(png_ptr->shift));
+#endif
 
-         if (row_info->color_type == PNG_COLOR_TYPE_RGB)
-            bytes_per_pixel = 6;
+#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
+   if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0)
+      png_do_write_swap_alpha(row_info, png_ptr->row_buf + 1);
+#endif
 
-         else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
-            bytes_per_pixel = 8;
+#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
+   if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
+      png_do_write_invert_alpha(row_info, png_ptr->row_buf + 1);
+#endif
 
-         else
-            return;
+#ifdef PNG_WRITE_BGR_SUPPORTED
+   if ((png_ptr->transformations & PNG_BGR) != 0)
+      png_do_bgr(row_info, png_ptr->row_buf + 1);
+#endif
 
-         for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
-         {
-            png_uint_32 s0   = (*(rp    ) << 8) | *(rp + 1);
-            png_uint_32 s1   = (*(rp + 2) << 8) | *(rp + 3);
-            png_uint_32 s2   = (*(rp + 4) << 8) | *(rp + 5);
-            png_uint_32 red  = (png_uint_32)((s0 - s1) & 0xffffL);
-            png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
-            *(rp    ) = (png_byte)((red >> 8) & 0xff);
-            *(rp + 1) = (png_byte)(red & 0xff);
-            *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
-            *(rp + 5) = (png_byte)(blue & 0xff);
-         }
-      }
-#endif /* PNG_WRITE_16BIT_SUPPORTED */
-   }
+#ifdef PNG_WRITE_INVERT_SUPPORTED
+   if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
+      png_do_invert(row_info, png_ptr->row_buf + 1);
+#endif
 }
-#endif /* PNG_MNG_FEATURES_SUPPORTED */
-#endif /* PNG_WRITE_SUPPORTED */
+#endif /* WRITE_TRANSFORMS */
+#endif /* WRITE */
diff --git a/src/3rdparty/libpng/pngwutil.c b/src/3rdparty/libpng/pngwutil.c
index b49704f..b289671 100644
--- a/src/3rdparty/libpng/pngwutil.c
+++ b/src/3rdparty/libpng/pngwutil.c
@@ -1,8 +1,8 @@
 
 /* pngwutil.c - utilities to write a PNG file
  *
- * Last changed in libpng 1.5.10 [March 8, 2012]
- * Copyright (c) 1998-2012 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.17 [March 26, 2015]
+ * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
@@ -23,29 +23,12 @@
 void PNGAPI
 png_save_uint_32(png_bytep buf, png_uint_32 i)
 {
-   buf[0] = (png_byte)((i >> 24) & 0xff);
-   buf[1] = (png_byte)((i >> 16) & 0xff);
-   buf[2] = (png_byte)((i >> 8) & 0xff);
-   buf[3] = (png_byte)(i & 0xff);
+   buf[0] = (png_byte)(i >> 24);
+   buf[1] = (png_byte)(i >> 16);
+   buf[2] = (png_byte)(i >> 8);
+   buf[3] = (png_byte)(i     );
 }
 
-#ifdef PNG_SAVE_INT_32_SUPPORTED
-/* The png_save_int_32 function assumes integers are stored in two's
- * complement format.  If this isn't the case, then this routine needs to
- * be modified to write data in two's complement format.  Note that,
- * the following works correctly even if png_int_32 has more than 32 bits
- * (compare the more complex code required on read for sign extention.)
- */
-void PNGAPI
-png_save_int_32(png_bytep buf, png_int_32 i)
-{
-   buf[0] = (png_byte)((i >> 24) & 0xff);
-   buf[1] = (png_byte)((i >> 16) & 0xff);
-   buf[2] = (png_byte)((i >> 8) & 0xff);
-   buf[3] = (png_byte)(i & 0xff);
-}
-#endif
-
 /* Place a 16-bit number into a buffer in PNG byte order.
  * The parameter is declared unsigned int, not png_uint_16,
  * just to avoid potential problems on pre-ANSI C compilers.
@@ -53,8 +36,8 @@ png_save_int_32(png_bytep buf, png_int_32 i)
 void PNGAPI
 png_save_uint_16(png_bytep buf, unsigned int i)
 {
-   buf[0] = (png_byte)((i >> 8) & 0xff);
-   buf[1] = (png_byte)(i & 0xff);
+   buf[0] = (png_byte)(i >> 8);
+   buf[1] = (png_byte)(i     );
 }
 #endif
 
@@ -65,7 +48,7 @@ png_save_uint_16(png_bytep buf, unsigned int i)
  * bytes have already been written.
  */
 void PNGAPI
-png_write_sig(png_structp png_ptr)
+png_write_sig(png_structrp png_ptr)
 {
    png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
 
@@ -87,7 +70,7 @@ png_write_sig(png_structp png_ptr)
  * passing in png_write_chunk_data().
  */
 static void
-png_write_chunk_header(png_structp png_ptr, png_uint_32 chunk_name,
+png_write_chunk_header(png_structrp png_ptr, png_uint_32 chunk_name,
     png_uint_32 length)
 {
    png_byte buf[8];
@@ -129,7 +112,7 @@ png_write_chunk_header(png_structp png_ptr, png_uint_32 chunk_name,
 }
 
 void PNGAPI
-png_write_chunk_start(png_structp png_ptr, png_const_bytep chunk_string,
+png_write_chunk_start(png_structrp png_ptr, png_const_bytep chunk_string,
     png_uint_32 length)
 {
    png_write_chunk_header(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), length);
@@ -141,7 +124,7 @@ png_write_chunk_start(png_structp png_ptr, png_const_bytep chunk_string,
  * given to png_write_chunk_header().
  */
 void PNGAPI
-png_write_chunk_data(png_structp png_ptr, png_const_bytep data,
+png_write_chunk_data(png_structrp png_ptr, png_const_bytep data,
     png_size_t length)
 {
    /* Write the data, and run the CRC over it */
@@ -153,7 +136,7 @@ png_write_chunk_data(png_structp png_ptr, png_const_bytep data,
       png_write_data(png_ptr, data, length);
 
       /* Update the CRC after writing the data,
-       * in case that the user I/O routine alters it.
+       * in case the user I/O routine alters it.
        */
       png_calculate_crc(png_ptr, data, length);
    }
@@ -161,7 +144,7 @@ png_write_chunk_data(png_structp png_ptr, png_const_bytep data,
 
 /* Finish a chunk started with png_write_chunk_header(). */
 void PNGAPI
-png_write_chunk_end(png_structp png_ptr)
+png_write_chunk_end(png_structrp png_ptr)
 {
    png_byte buf[4];
 
@@ -190,15 +173,15 @@ png_write_chunk_end(png_structp png_ptr)
  * functions instead.
  */
 static void
-png_write_complete_chunk(png_structp png_ptr, png_uint_32 chunk_name,
+png_write_complete_chunk(png_structrp png_ptr, png_uint_32 chunk_name,
    png_const_bytep data, png_size_t length)
 {
    if (png_ptr == NULL)
       return;
 
    /* On 64 bit architectures 'length' may not fit in a png_uint_32. */
-   if (length > PNG_UINT_32_MAX)
-      png_error(png_ptr, "length exceeds PNG maxima");
+   if (length > PNG_UINT_31_MAX)
+      png_error(png_ptr, "length exceeds PNG maximum");
 
    png_write_chunk_header(png_ptr, chunk_name, (png_uint_32)length);
    png_write_chunk_data(png_ptr, data, length);
@@ -207,474 +190,571 @@ png_write_complete_chunk(png_structp png_ptr, png_uint_32 chunk_name,
 
 /* This is the API that calls the internal function above. */
 void PNGAPI
-png_write_chunk(png_structp png_ptr, png_const_bytep chunk_string,
+png_write_chunk(png_structrp png_ptr, png_const_bytep chunk_string,
    png_const_bytep data, png_size_t length)
 {
    png_write_complete_chunk(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), data,
       length);
 }
 
-/* Initialize the compressor for the appropriate type of compression. */
-static void
-png_zlib_claim(png_structp png_ptr, png_uint_32 state)
+/* This is used below to find the size of an image to pass to png_deflate_claim,
+ * so it only needs to be accurate if the size is less than 16384 bytes (the
+ * point at which a lower LZ window size can be used.)
+ */
+static png_alloc_size_t
+png_image_size(png_structrp png_ptr)
 {
-   if (!(png_ptr->zlib_state & PNG_ZLIB_IN_USE))
+   /* Only return sizes up to the maximum of a png_uint_32; do this by limiting
+    * the width and height used to 15 bits.
+    */
+   png_uint_32 h = png_ptr->height;
+
+   if (png_ptr->rowbytes < 32768 && h < 32768)
    {
-      /* If already initialized for 'state' do not re-init. */
-      if (png_ptr->zlib_state != state)
+      if (png_ptr->interlaced != 0)
       {
-         int ret = Z_OK;
-         png_const_charp who = "-";
+         /* Interlacing makes the image larger because of the replication of
+          * both the filter byte and the padding to a byte boundary.
+          */
+         png_uint_32 w = png_ptr->width;
+         unsigned int pd = png_ptr->pixel_depth;
+         png_alloc_size_t cb_base;
+         int pass;
 
-         /* If actually initialized for another state do a deflateEnd. */
-         if (png_ptr->zlib_state != PNG_ZLIB_UNINITIALIZED)
+         for (cb_base=0, pass=0; pass<=6; ++pass)
          {
-            ret = deflateEnd(&png_ptr->zstream);
-            who = "end";
-            png_ptr->zlib_state = PNG_ZLIB_UNINITIALIZED;
+            png_uint_32 pw = PNG_PASS_COLS(w, pass);
+
+            if (pw > 0)
+               cb_base += (PNG_ROWBYTES(pd, pw)+1) * PNG_PASS_ROWS(h, pass);
          }
 
-         /* zlib itself detects an incomplete state on deflateEnd */
-         if (ret == Z_OK) switch (state)
+         return cb_base;
+      }
+
+      else
+         return (png_ptr->rowbytes+1) * h;
+   }
+
+   else
+      return 0xffffffffU;
+}
+
+#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
+   /* This is the code to hack the first two bytes of the deflate stream (the
+    * deflate header) to correct the windowBits value to match the actual data
+    * size.  Note that the second argument is the *uncompressed* size but the
+    * first argument is the *compressed* data (and it must be deflate
+    * compressed.)
+    */
+static void
+optimize_cmf(png_bytep data, png_alloc_size_t data_size)
+{
+   /* Optimize the CMF field in the zlib stream.  The resultant zlib stream is
+    * still compliant to the stream specification.
+    */
+   if (data_size <= 16384) /* else windowBits must be 15 */
+   {
+      unsigned int z_cmf = data[0];  /* zlib compression method and flags */
+
+      if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
+      {
+         unsigned int z_cinfo;
+         unsigned int half_z_window_size;
+
+         z_cinfo = z_cmf >> 4;
+         half_z_window_size = 1U << (z_cinfo + 7);
+
+         if (data_size <= half_z_window_size) /* else no change */
          {
-#           ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
-               case PNG_ZLIB_FOR_TEXT:
-                  ret = deflateInit2(&png_ptr->zstream,
-                     png_ptr->zlib_text_level, png_ptr->zlib_text_method,
-                     png_ptr->zlib_text_window_bits,
-                     png_ptr->zlib_text_mem_level, png_ptr->zlib_text_strategy);
-                  who = "text";
-                  break;
-#           endif
+            unsigned int tmp;
 
-            case PNG_ZLIB_FOR_IDAT:
-               ret = deflateInit2(&png_ptr->zstream, png_ptr->zlib_level,
-                   png_ptr->zlib_method, png_ptr->zlib_window_bits,
-                   png_ptr->zlib_mem_level, png_ptr->zlib_strategy);
-               who = "IDAT";
-               break;
+            do
+            {
+               half_z_window_size >>= 1;
+               --z_cinfo;
+            }
+            while (z_cinfo > 0 && data_size <= half_z_window_size);
 
-            default:
-               png_error(png_ptr, "invalid zlib state");
+            z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
+
+            data[0] = (png_byte)z_cmf;
+            tmp = data[1] & 0xe0;
+            tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
+            data[1] = (png_byte)tmp;
          }
+      }
+   }
+}
+#endif /* WRITE_OPTIMIZE_CMF */
 
-         if (ret == Z_OK)
-            png_ptr->zlib_state = state;
+/* Initialize the compressor for the appropriate type of compression. */
+static int
+png_deflate_claim(png_structrp png_ptr, png_uint_32 owner,
+   png_alloc_size_t data_size)
+{
+   if (png_ptr->zowner != 0)
+   {
+#if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_ERROR_TEXT_SUPPORTED)
+      char msg[64];
+
+      PNG_STRING_FROM_CHUNK(msg, owner);
+      msg[4] = ':';
+      msg[5] = ' ';
+      PNG_STRING_FROM_CHUNK(msg+6, png_ptr->zowner);
+      /* So the message that results is "<chunk> using zstream"; this is an
+       * internal error, but is very useful for debugging.  i18n requirements
+       * are minimal.
+       */
+      (void)png_safecat(msg, (sizeof msg), 10, " using zstream");
+#endif
+#if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC
+         png_warning(png_ptr, msg);
 
-         else /* an error in deflateEnd or deflateInit2 */
+         /* Attempt sane error recovery */
+         if (png_ptr->zowner == png_IDAT) /* don't steal from IDAT */
          {
-            size_t pos = 0;
-            char msg[64];
+            png_ptr->zstream.msg = PNGZ_MSG_CAST("in use by IDAT");
+            return Z_STREAM_ERROR;
+         }
 
-            pos = png_safecat(msg, sizeof msg, pos,
-               "zlib failed to initialize compressor (");
-            pos = png_safecat(msg, sizeof msg, pos, who);
+         png_ptr->zowner = 0;
+#else
+         png_error(png_ptr, msg);
+#endif
+   }
 
-            switch (ret)
-            {
-               case Z_VERSION_ERROR:
-                  pos = png_safecat(msg, sizeof msg, pos, ") version error");
-                  break;
+   {
+      int level = png_ptr->zlib_level;
+      int method = png_ptr->zlib_method;
+      int windowBits = png_ptr->zlib_window_bits;
+      int memLevel = png_ptr->zlib_mem_level;
+      int strategy; /* set below */
+      int ret; /* zlib return code */
 
-               case Z_STREAM_ERROR:
-                  pos = png_safecat(msg, sizeof msg, pos, ") stream error");
-                  break;
+      if (owner == png_IDAT)
+      {
+         if ((png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY) != 0)
+            strategy = png_ptr->zlib_strategy;
 
-               case Z_MEM_ERROR:
-                  pos = png_safecat(msg, sizeof msg, pos, ") memory error");
-                  break;
+         else if (png_ptr->do_filter != PNG_FILTER_NONE)
+            strategy = PNG_Z_DEFAULT_STRATEGY;
 
-               default:
-                  pos = png_safecat(msg, sizeof msg, pos, ") unknown error");
-                  break;
-            }
+         else
+            strategy = PNG_Z_DEFAULT_NOFILTER_STRATEGY;
+      }
+
+      else
+      {
+#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
+            level = png_ptr->zlib_text_level;
+            method = png_ptr->zlib_text_method;
+            windowBits = png_ptr->zlib_text_window_bits;
+            memLevel = png_ptr->zlib_text_mem_level;
+            strategy = png_ptr->zlib_text_strategy;
+#else
+            /* If customization is not supported the values all come from the
+             * IDAT values except for the strategy, which is fixed to the
+             * default.  (This is the pre-1.6.0 behavior too, although it was
+             * implemented in a very different way.)
+             */
+            strategy = Z_DEFAULT_STRATEGY;
+#endif
+      }
 
-            png_error(png_ptr, msg);
+      /* Adjust 'windowBits' down if larger than 'data_size'; to stop this
+       * happening just pass 32768 as the data_size parameter.  Notice that zlib
+       * requires an extra 262 bytes in the window in addition to the data to be
+       * able to see the whole of the data, so if data_size+262 takes us to the
+       * next windowBits size we need to fix up the value later.  (Because even
+       * though deflate needs the extra window, inflate does not!)
+       */
+      if (data_size <= 16384)
+      {
+         /* IMPLEMENTATION NOTE: this 'half_window_size' stuff is only here to
+          * work round a Microsoft Visual C misbehavior which, contrary to C-90,
+          * widens the result of the following shift to 64-bits if (and,
+          * apparently, only if) it is used in a test.
+          */
+         unsigned int half_window_size = 1U << (windowBits-1);
+
+         while (data_size + 262 <= half_window_size)
+         {
+            half_window_size >>= 1;
+            --windowBits;
          }
       }
 
-      /* Here on success, claim the zstream: */
-      png_ptr->zlib_state |= PNG_ZLIB_IN_USE;
-   }
+      /* Check against the previous initialized values, if any. */
+      if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0 &&
+         (png_ptr->zlib_set_level != level ||
+         png_ptr->zlib_set_method != method ||
+         png_ptr->zlib_set_window_bits != windowBits ||
+         png_ptr->zlib_set_mem_level != memLevel ||
+         png_ptr->zlib_set_strategy != strategy))
+      {
+         if (deflateEnd(&png_ptr->zstream) != Z_OK)
+            png_warning(png_ptr, "deflateEnd failed (ignored)");
 
-   else
-      png_error(png_ptr, "zstream already in use (internal error)");
-}
+         png_ptr->flags &= ~PNG_FLAG_ZSTREAM_INITIALIZED;
+      }
 
-/* The opposite: release the stream.  It is also reset, this API will warn on
- * error but will not fail.
- */
-static void
-png_zlib_release(png_structp png_ptr)
-{
-   if (png_ptr->zlib_state & PNG_ZLIB_IN_USE)
-   {
-      int ret = deflateReset(&png_ptr->zstream);
+      /* For safety clear out the input and output pointers (currently zlib
+       * doesn't use them on Init, but it might in the future).
+       */
+      png_ptr->zstream.next_in = NULL;
+      png_ptr->zstream.avail_in = 0;
+      png_ptr->zstream.next_out = NULL;
+      png_ptr->zstream.avail_out = 0;
 
-      png_ptr->zlib_state &= ~PNG_ZLIB_IN_USE;
+      /* Now initialize if required, setting the new parameters, otherwise just
+       * to a simple reset to the previous parameters.
+       */
+      if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
+         ret = deflateReset(&png_ptr->zstream);
 
-      if (ret != Z_OK)
+      else
       {
-         png_const_charp err;
-         PNG_WARNING_PARAMETERS(p)
+         ret = deflateInit2(&png_ptr->zstream, level, method, windowBits,
+            memLevel, strategy);
 
-         switch (ret)
-         {
-            case Z_VERSION_ERROR:
-               err = "version";
-               break;
+         if (ret == Z_OK)
+            png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
+      }
 
-            case Z_STREAM_ERROR:
-               err = "stream";
-               break;
+      /* The return code is from either deflateReset or deflateInit2; they have
+       * pretty much the same set of error codes.
+       */
+      if (ret == Z_OK)
+         png_ptr->zowner = owner;
 
-            case Z_MEM_ERROR:
-               err = "memory";
-               break;
+      else
+         png_zstream_error(png_ptr, ret);
 
-            default:
-               err = "unknown";
-               break;
-         }
+      return ret;
+   }
+}
 
-         png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_d, ret);
-         png_warning_parameter(p, 2, err);
+/* Clean up (or trim) a linked list of compression buffers. */
+void /* PRIVATE */
+png_free_buffer_list(png_structrp png_ptr, png_compression_bufferp *listp)
+{
+   png_compression_bufferp list = *listp;
 
-         if (png_ptr->zstream.msg)
-            err = png_ptr->zstream.msg;
-         else
-            err = "[no zlib message]";
+   if (list != NULL)
+   {
+      *listp = NULL;
 
-         png_warning_parameter(p, 3, err);
+      do
+      {
+         png_compression_bufferp next = list->next;
 
-         png_formatted_warning(png_ptr, p,
-            "zlib failed to reset compressor: @1(@2): @3");
+         png_free(png_ptr, list);
+         list = next;
       }
+      while (list != NULL);
    }
-
-   else
-      png_warning(png_ptr, "zstream not in use (internal error)");
 }
 
 #ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
 /* This pair of functions encapsulates the operation of (a) compressing a
  * text string, and (b) issuing it later as a series of chunk data writes.
  * The compression_state structure is shared context for these functions
- * set up by the caller in order to make the whole mess thread-safe.
+ * set up by the caller to allow access to the relevant local variables.
+ *
+ * compression_buffer (new in 1.6.0) is just a linked list of zbuffer_size
+ * temporary buffers.  From 1.6.0 it is retained in png_struct so that it will
+ * be correctly freed in the event of a write error (previous implementations
+ * just leaked memory.)
  */
-
 typedef struct
 {
-   png_const_bytep input;   /* The uncompressed input data */
-   png_size_t input_len;    /* Its length */
-   int num_output_ptr;      /* Number of output pointers used */
-   int max_output_ptr;      /* Size of output_ptr */
-   png_bytep *output_ptr;   /* Array of pointers to output */
+   png_const_bytep      input;        /* The uncompressed input data */
+   png_alloc_size_t     input_len;    /* Its length */
+   png_uint_32          output_len;   /* Final compressed length */
+   png_byte             output[1024]; /* First block of output */
 } compression_state;
 
-/* Compress given text into storage in the png_ptr structure */
-static int /* PRIVATE */
-png_text_compress(png_structp png_ptr,
-    png_const_charp text, png_size_t text_len, int compression,
-    compression_state *comp)
+static void
+png_text_compress_init(compression_state *comp, png_const_bytep input,
+   png_alloc_size_t input_len)
 {
-   int ret;
-
-   comp->num_output_ptr = 0;
-   comp->max_output_ptr = 0;
-   comp->output_ptr = NULL;
-   comp->input = NULL;
-   comp->input_len = text_len;
-
-   /* We may just want to pass the text right through */
-   if (compression == PNG_TEXT_COMPRESSION_NONE)
-   {
-      comp->input = (png_const_bytep)text;
-      return((int)text_len);
-   }
-
-   if (compression >= PNG_TEXT_COMPRESSION_LAST)
-   {
-      PNG_WARNING_PARAMETERS(p)
+   comp->input = input;
+   comp->input_len = input_len;
+   comp->output_len = 0;
+}
 
-      png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_d,
-         compression);
-      png_formatted_warning(png_ptr, p, "Unknown compression type @1");
-   }
+/* Compress the data in the compression state input */
+static int
+png_text_compress(png_structrp png_ptr, png_uint_32 chunk_name,
+   compression_state *comp, png_uint_32 prefix_len)
+{
+   int ret;
 
-   /* We can't write the chunk until we find out how much data we have,
-    * which means we need to run the compressor first and save the
-    * output.  This shouldn't be a problem, as the vast majority of
-    * comments should be reasonable, but we will set up an array of
-    * malloc'd pointers to be sure.
+   /* To find the length of the output it is necessary to first compress the
+    * input. The result is buffered rather than using the two-pass algorithm
+    * that is used on the inflate side; deflate is assumed to be slower and a
+    * PNG writer is assumed to have more memory available than a PNG reader.
     *
-    * If we knew the application was well behaved, we could simplify this
-    * greatly by assuming we can always malloc an output buffer large
-    * enough to hold the compressed text ((1001 * text_len / 1000) + 12)
-    * and malloc this directly.  The only time this would be a bad idea is
-    * if we can't malloc more than 64K and we have 64K of random input
-    * data, or if the input string is incredibly large (although this
-    * wouldn't cause a failure, just a slowdown due to swapping).
+    * IMPLEMENTATION NOTE: the zlib API deflateBound() can be used to find an
+    * upper limit on the output size, but it is always bigger than the input
+    * size so it is likely to be more efficient to use this linked-list
+    * approach.
     */
-   png_zlib_claim(png_ptr, PNG_ZLIB_FOR_TEXT);
+   ret = png_deflate_claim(png_ptr, chunk_name, comp->input_len);
 
-   /* Set up the compression buffers */
-   /* TODO: the following cast hides a potential overflow problem. */
-   png_ptr->zstream.avail_in = (uInt)text_len;
+   if (ret != Z_OK)
+      return ret;
 
-   /* NOTE: assume zlib doesn't overwrite the input */
-   png_ptr->zstream.next_in = (Bytef *)text;
-   png_ptr->zstream.avail_out = png_ptr->zbuf_size;
-   png_ptr->zstream.next_out = png_ptr->zbuf;
-
-   /* This is the same compression loop as in png_write_row() */
-   do
+   /* Set up the compression buffers, we need a loop here to avoid overflowing a
+    * uInt.  Use ZLIB_IO_MAX to limit the input.  The output is always limited
+    * by the output buffer size, so there is no need to check that.  Since this
+    * is ANSI-C we know that an 'int', hence a uInt, is always at least 16 bits
+    * in size.
+    */
    {
-      /* Compress the data */
-      ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);
+      png_compression_bufferp *end = &png_ptr->zbuffer_list;
+      png_alloc_size_t input_len = comp->input_len; /* may be zero! */
+      png_uint_32 output_len;
 
-      if (ret != Z_OK)
-      {
-         /* Error */
-         if (png_ptr->zstream.msg != NULL)
-            png_error(png_ptr, png_ptr->zstream.msg);
+      /* zlib updates these for us: */
+      png_ptr->zstream.next_in = PNGZ_INPUT_CAST(comp->input);
+      png_ptr->zstream.avail_in = 0; /* Set below */
+      png_ptr->zstream.next_out = comp->output;
+      png_ptr->zstream.avail_out = (sizeof comp->output);
 
-         else
-            png_error(png_ptr, "zlib error");
-      }
+      output_len = png_ptr->zstream.avail_out;
 
-      /* Check to see if we need more room */
-      if (!(png_ptr->zstream.avail_out))
+      do
       {
-         /* Make sure the output array has room */
-         if (comp->num_output_ptr >= comp->max_output_ptr)
-         {
-            int old_max;
+         uInt avail_in = ZLIB_IO_MAX;
 
-            old_max = comp->max_output_ptr;
-            comp->max_output_ptr = comp->num_output_ptr + 4;
-            if (comp->output_ptr != NULL)
-            {
-               png_bytepp old_ptr;
+         if (avail_in > input_len)
+            avail_in = (uInt)input_len;
 
-               old_ptr = comp->output_ptr;
+         input_len -= avail_in;
 
-               comp->output_ptr = (png_bytepp)png_malloc(png_ptr,
-                   (png_alloc_size_t)
-                   (comp->max_output_ptr * png_sizeof(png_charpp)));
+         png_ptr->zstream.avail_in = avail_in;
 
-               png_memcpy(comp->output_ptr, old_ptr, old_max
-                   * png_sizeof(png_charp));
+         if (png_ptr->zstream.avail_out == 0)
+         {
+            png_compression_buffer *next;
 
-               png_free(png_ptr, old_ptr);
+            /* Chunk data is limited to 2^31 bytes in length, so the prefix
+             * length must be counted here.
+             */
+            if (output_len + prefix_len > PNG_UINT_31_MAX)
+            {
+               ret = Z_MEM_ERROR;
+               break;
             }
-            else
-               comp->output_ptr = (png_bytepp)png_malloc(png_ptr,
-                   (png_alloc_size_t)
-                   (comp->max_output_ptr * png_sizeof(png_charp)));
-         }
-
-         /* Save the data */
-         comp->output_ptr[comp->num_output_ptr] =
-             (png_bytep)png_malloc(png_ptr,
-             (png_alloc_size_t)png_ptr->zbuf_size);
-
-         png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,
-             png_ptr->zbuf_size);
 
-         comp->num_output_ptr++;
-
-         /* and reset the buffer */
-         png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
-         png_ptr->zstream.next_out = png_ptr->zbuf;
-      }
-   /* Continue until we don't have any more to compress */
-   } while (png_ptr->zstream.avail_in);
-
-   /* Finish the compression */
-   do
-   {
-      /* Tell zlib we are finished */
-      ret = deflate(&png_ptr->zstream, Z_FINISH);
-
-      if (ret == Z_OK)
-      {
-         /* Check to see if we need more room */
-         if (!(png_ptr->zstream.avail_out))
-         {
-            /* Check to make sure our output array has room */
-            if (comp->num_output_ptr >= comp->max_output_ptr)
+            /* Need a new (malloc'ed) buffer, but there may be one present
+             * already.
+             */
+            next = *end;
+            if (next == NULL)
             {
-               int old_max;
+               next = png_voidcast(png_compression_bufferp, png_malloc_base
+                  (png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr)));
 
-               old_max = comp->max_output_ptr;
-               comp->max_output_ptr = comp->num_output_ptr + 4;
-               if (comp->output_ptr != NULL)
+               if (next == NULL)
                {
-                  png_bytepp old_ptr;
-
-                  old_ptr = comp->output_ptr;
-
-                  /* This could be optimized to realloc() */
-                  comp->output_ptr = (png_bytepp)png_malloc(png_ptr,
-                      (png_alloc_size_t)(comp->max_output_ptr *
-                      png_sizeof(png_charp)));
-
-                  png_memcpy(comp->output_ptr, old_ptr,
-                      old_max * png_sizeof(png_charp));
-
-                  png_free(png_ptr, old_ptr);
+                  ret = Z_MEM_ERROR;
+                  break;
                }
 
-               else
-                  comp->output_ptr = (png_bytepp)png_malloc(png_ptr,
-                      (png_alloc_size_t)(comp->max_output_ptr *
-                      png_sizeof(png_charp)));
+               /* Link in this buffer (so that it will be freed later) */
+               next->next = NULL;
+               *end = next;
             }
 
-            /* Save the data */
-            comp->output_ptr[comp->num_output_ptr] =
-                (png_bytep)png_malloc(png_ptr,
-                (png_alloc_size_t)png_ptr->zbuf_size);
+            png_ptr->zstream.next_out = next->output;
+            png_ptr->zstream.avail_out = png_ptr->zbuffer_size;
+            output_len += png_ptr->zstream.avail_out;
 
-            png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,
-                png_ptr->zbuf_size);
+            /* Move 'end' to the next buffer pointer. */
+            end = &next->next;
+         }
 
-            comp->num_output_ptr++;
+         /* Compress the data */
+         ret = deflate(&png_ptr->zstream,
+            input_len > 0 ? Z_NO_FLUSH : Z_FINISH);
 
-            /* and reset the buffer pointers */
-            png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
-            png_ptr->zstream.next_out = png_ptr->zbuf;
-         }
+         /* Claw back input data that was not consumed (because avail_in is
+          * reset above every time round the loop).
+          */
+         input_len += png_ptr->zstream.avail_in;
+         png_ptr->zstream.avail_in = 0; /* safety */
       }
-      else if (ret != Z_STREAM_END)
-      {
-         /* We got an error */
-         if (png_ptr->zstream.msg != NULL)
-            png_error(png_ptr, png_ptr->zstream.msg);
+      while (ret == Z_OK);
 
-         else
-            png_error(png_ptr, "zlib error");
+      /* There may be some space left in the last output buffer. This needs to
+       * be subtracted from output_len.
+       */
+      output_len -= png_ptr->zstream.avail_out;
+      png_ptr->zstream.avail_out = 0; /* safety */
+      comp->output_len = output_len;
+
+      /* Now double check the output length, put in a custom message if it is
+       * too long.  Otherwise ensure the z_stream::msg pointer is set to
+       * something.
+       */
+      if (output_len + prefix_len >= PNG_UINT_31_MAX)
+      {
+         png_ptr->zstream.msg = PNGZ_MSG_CAST("compressed data too long");
+         ret = Z_MEM_ERROR;
       }
-   } while (ret != Z_STREAM_END);
 
-   /* Text length is number of buffers plus last buffer */
-   text_len = png_ptr->zbuf_size * comp->num_output_ptr;
+      else
+         png_zstream_error(png_ptr, ret);
+
+      /* Reset zlib for another zTXt/iTXt or image data */
+      png_ptr->zowner = 0;
 
-   if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
-      text_len += png_ptr->zbuf_size - (png_size_t)png_ptr->zstream.avail_out;
+      /* The only success case is Z_STREAM_END, input_len must be 0; if not this
+       * is an internal error.
+       */
+      if (ret == Z_STREAM_END && input_len == 0)
+      {
+#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
+         /* Fix up the deflate header, if required */
+         optimize_cmf(comp->output, comp->input_len);
+#endif
+         /* But Z_OK is returned, not Z_STREAM_END; this allows the claim
+          * function above to return Z_STREAM_END on an error (though it never
+          * does in the current versions of zlib.)
+          */
+         return Z_OK;
+      }
 
-   return((int)text_len);
+      else
+         return ret;
+   }
 }
 
 /* Ship the compressed text out via chunk writes */
-static void /* PRIVATE */
-png_write_compressed_data_out(png_structp png_ptr, compression_state *comp,
-   png_size_t data_len)
+static void
+png_write_compressed_data_out(png_structrp png_ptr, compression_state *comp)
 {
-   int i;
+   png_uint_32 output_len = comp->output_len;
+   png_const_bytep output = comp->output;
+   png_uint_32 avail = (sizeof comp->output);
+   png_compression_buffer *next = png_ptr->zbuffer_list;
 
-   /* Handle the no-compression case */
-   if (comp->input)
+   for (;;)
    {
-      png_write_chunk_data(png_ptr, comp->input, data_len);
+      if (avail > output_len)
+         avail = output_len;
 
-      return;
-   }
+      png_write_chunk_data(png_ptr, output, avail);
 
-#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
-   /* The zbuf_size test is because the code below doesn't work if zbuf_size is
-    * '1'; simply skip it to avoid memory overwrite.
-    */
-   if (data_len >= 2 && comp->input_len < 16384 && png_ptr->zbuf_size > 1)
-   {
-      unsigned int z_cmf;  /* zlib compression method and flags */
+      output_len -= avail;
 
-      /* Optimize the CMF field in the zlib stream.  This hack of the zlib
-       * stream is compliant to the stream specification.
-       */
+      if (output_len == 0 || next == NULL)
+         break;
 
-      if (comp->num_output_ptr)
-        z_cmf = comp->output_ptr[0][0];
-      else
-        z_cmf = png_ptr->zbuf[0];
+      avail = png_ptr->zbuffer_size;
+      output = next->output;
+      next = next->next;
+   }
 
-      if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
-      {
-         unsigned int z_cinfo;
-         unsigned int half_z_window_size;
-         png_size_t uncompressed_text_size = comp->input_len;
+   /* This is an internal error; 'next' must have been NULL! */
+   if (output_len > 0)
+      png_error(png_ptr, "error writing ancillary chunked compressed data");
+}
+#endif /* WRITE_COMPRESSED_TEXT */
 
-         z_cinfo = z_cmf >> 4;
-         half_z_window_size = 1 << (z_cinfo + 7);
+#if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_pCAL_SUPPORTED) || \
+    defined(PNG_WRITE_iCCP_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
+/* Check that the tEXt or zTXt keyword is valid per PNG 1.0 specification,
+ * and if invalid, correct the keyword rather than discarding the entire
+ * chunk.  The PNG 1.0 specification requires keywords 1-79 characters in
+ * length, forbids leading or trailing whitespace, multiple internal spaces,
+ * and the non-break space (0x80) from ISO 8859-1.  Returns keyword length.
+ *
+ * The 'new_key' buffer must be 80 characters in size (for the keyword plus a
+ * trailing '\0').  If this routine returns 0 then there was no keyword, or a
+ * valid one could not be generated, and the caller must png_error.
+ */
+static png_uint_32
+png_check_keyword(png_structrp png_ptr, png_const_charp key, png_bytep new_key)
+{
+   png_const_charp orig_key = key;
+   png_uint_32 key_len = 0;
+   int bad_character = 0;
+   int space = 1;
 
-         while (uncompressed_text_size <= half_z_window_size &&
-             half_z_window_size >= 256)
-         {
-            z_cinfo--;
-            half_z_window_size >>= 1;
-         }
+   png_debug(1, "in png_check_keyword");
 
-         z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
+   if (key == NULL)
+   {
+      *new_key = 0;
+      return 0;
+   }
 
-         if (comp->num_output_ptr)
-         {
+   while (*key && key_len < 79)
+   {
+      png_byte ch = (png_byte)*key++;
 
-           if (comp->output_ptr[0][0] != z_cmf)
-           {
-              int tmp;
+      if ((ch > 32 && ch <= 126) || (ch >= 161 /*&& ch <= 255*/))
+         *new_key++ = ch, ++key_len, space = 0;
 
-              comp->output_ptr[0][0] = (png_byte)z_cmf;
-              tmp = comp->output_ptr[0][1] & 0xe0;
-              tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
-              comp->output_ptr[0][1] = (png_byte)tmp;
-           }
-         }
-         else
-         {
-            int tmp;
+      else if (space == 0)
+      {
+         /* A space or an invalid character when one wasn't seen immediately
+          * before; output just a space.
+          */
+         *new_key++ = 32, ++key_len, space = 1;
 
-            png_ptr->zbuf[0] = (png_byte)z_cmf;
-            tmp = png_ptr->zbuf[1] & 0xe0;
-            tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
-            png_ptr->zbuf[1] = (png_byte)tmp;
-         }
+         /* If the character was not a space then it is invalid. */
+         if (ch != 32)
+            bad_character = ch;
       }
 
-      else
-         png_error(png_ptr,
-             "Invalid zlib compression method or flags in non-IDAT chunk");
+      else if (bad_character == 0)
+         bad_character = ch; /* just skip it, record the first error */
    }
-#endif /* PNG_WRITE_OPTIMIZE_CMF_SUPPORTED */
 
-   /* Write saved output buffers, if any */
-   for (i = 0; i < comp->num_output_ptr; i++)
+   if (key_len > 0 && space != 0) /* trailing space */
    {
-      png_write_chunk_data(png_ptr, comp->output_ptr[i],
-          (png_size_t)png_ptr->zbuf_size);
-
-      png_free(png_ptr, comp->output_ptr[i]);
+      --key_len, --new_key;
+      if (bad_character == 0)
+         bad_character = 32;
    }
 
-   if (comp->max_output_ptr != 0)
-      png_free(png_ptr, comp->output_ptr);
+   /* Terminate the keyword */
+   *new_key = 0;
+
+   if (key_len == 0)
+      return 0;
 
-   /* Write anything left in zbuf */
-   if (png_ptr->zstream.avail_out < (png_uint_32)png_ptr->zbuf_size)
-      png_write_chunk_data(png_ptr, png_ptr->zbuf,
-          (png_size_t)(png_ptr->zbuf_size - png_ptr->zstream.avail_out));
+#ifdef PNG_WARNINGS_SUPPORTED
+   /* Try to only output one warning per keyword: */
+   if (*key != 0) /* keyword too long */
+      png_warning(png_ptr, "keyword truncated");
 
-   /* Reset zlib for another zTXt/iTXt or image data */
-   png_zlib_release(png_ptr);
+   else if (bad_character != 0)
+   {
+      PNG_WARNING_PARAMETERS(p)
+
+      png_warning_parameter(p, 1, orig_key);
+      png_warning_parameter_signed(p, 2, PNG_NUMBER_FORMAT_02x, bad_character);
+
+      png_formatted_warning(png_ptr, p, "keyword \"@1\": bad character '0x@2'");
+   }
+#endif /* WARNINGS */
+
+   return key_len;
 }
-#endif /* PNG_WRITE_COMPRESSED_TEXT_SUPPORTED */
+#endif /* WRITE_TEXT || WRITE_pCAL || WRITE_iCCP || WRITE_sPLT */
 
 /* Write the IHDR chunk, and update the png_struct with the necessary
  * information.  Note that the rest of this code depends upon this
  * information being correct.
  */
 void /* PRIVATE */
-png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
+png_write_IHDR(png_structrp png_ptr, png_uint_32 width, png_uint_32 height,
     int bit_depth, int color_type, int compression_type, int filter_type,
     int interlace_type)
 {
@@ -768,8 +848,8 @@ png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
     */
    if (
 #ifdef PNG_MNG_FEATURES_SUPPORTED
-       !((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
-       ((png_ptr->mode&PNG_HAVE_PNG_SIGNATURE) == 0) &&
+       !((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
+       ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) &&
        (color_type == PNG_COLOR_TYPE_RGB ||
         color_type == PNG_COLOR_TYPE_RGB_ALPHA) &&
        (filter_type == PNG_INTRAPIXEL_DIFFERENCING)) &&
@@ -791,7 +871,7 @@ png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
    interlace_type=PNG_INTERLACE_NONE;
 #endif
 
-   /* Save the relevent information */
+   /* Save the relevant information */
    png_ptr->bit_depth = (png_byte)bit_depth;
    png_ptr->color_type = (png_byte)color_type;
    png_ptr->interlaced = (png_byte)interlace_type;
@@ -821,12 +901,7 @@ png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
    /* Write the chunk */
    png_write_complete_chunk(png_ptr, png_IHDR, buf, (png_size_t)13);
 
-   /* Initialize zlib with PNG info */
-   png_ptr->zstream.zalloc = png_zalloc;
-   png_ptr->zstream.zfree = png_zfree;
-   png_ptr->zstream.opaque = (voidpf)png_ptr;
-
-   if (!(png_ptr->do_filter))
+   if ((png_ptr->do_filter) == PNG_NO_FILTERS)
    {
       if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
           png_ptr->bit_depth < 8)
@@ -836,55 +911,6 @@ png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
          png_ptr->do_filter = PNG_ALL_FILTERS;
    }
 
-   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY))
-   {
-      if (png_ptr->do_filter != PNG_FILTER_NONE)
-         png_ptr->zlib_strategy = Z_FILTERED;
-
-      else
-         png_ptr->zlib_strategy = Z_DEFAULT_STRATEGY;
-   }
-
-   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_LEVEL))
-      png_ptr->zlib_level = Z_DEFAULT_COMPRESSION;
-
-   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL))
-      png_ptr->zlib_mem_level = 8;
-
-   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS))
-      png_ptr->zlib_window_bits = 15;
-
-   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_METHOD))
-      png_ptr->zlib_method = 8;
-
-#ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
-#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
-   if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_STRATEGY))
-      png_ptr->zlib_text_strategy = Z_DEFAULT_STRATEGY;
-
-   if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_LEVEL))
-      png_ptr->zlib_text_level = png_ptr->zlib_level;
-
-   if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_MEM_LEVEL))
-      png_ptr->zlib_text_mem_level = png_ptr->zlib_mem_level;
-
-   if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_WINDOW_BITS))
-      png_ptr->zlib_text_window_bits = png_ptr->zlib_window_bits;
-
-   if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_METHOD))
-      png_ptr->zlib_text_method = png_ptr->zlib_method;
-#else
-   png_ptr->zlib_text_strategy = Z_DEFAULT_STRATEGY;
-   png_ptr->zlib_text_level = png_ptr->zlib_level;
-   png_ptr->zlib_text_mem_level = png_ptr->zlib_mem_level;
-   png_ptr->zlib_text_window_bits = png_ptr->zlib_window_bits;
-   png_ptr->zlib_text_method = png_ptr->zlib_method;
-#endif /* PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED */
-#endif /* PNG_WRITE_COMPRESSED_TEXT_SUPPORTED */
-
-   /* Record that the compressor has not yet been initialized. */
-   png_ptr->zlib_state = PNG_ZLIB_UNINITIALIZED;
-
    png_ptr->mode = PNG_HAVE_IHDR; /* not READY_FOR_ZTXT */
 }
 
@@ -893,7 +919,7 @@ png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
  * structure.
  */
 void /* PRIVATE */
-png_write_PLTE(png_structp png_ptr, png_const_colorp palette,
+png_write_PLTE(png_structrp png_ptr, png_const_colorp palette,
     png_uint_32 num_pal)
 {
    png_uint_32 i;
@@ -904,7 +930,7 @@ png_write_PLTE(png_structp png_ptr, png_const_colorp palette,
 
    if ((
 #ifdef PNG_MNG_FEATURES_SUPPORTED
-       !(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) &&
+       (png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0 &&
 #endif
        num_pal == 0) || num_pal > 256)
    {
@@ -920,7 +946,7 @@ png_write_PLTE(png_structp png_ptr, png_const_colorp palette,
       }
    }
 
-   if (!(png_ptr->color_type&PNG_COLOR_MASK_COLOR))
+   if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
    {
       png_warning(png_ptr,
           "Ignoring request to write a PLTE chunk in grayscale PNG");
@@ -961,94 +987,165 @@ png_write_PLTE(png_structp png_ptr, png_const_colorp palette,
    png_ptr->mode |= PNG_HAVE_PLTE;
 }
 
-/* Write an IDAT chunk */
+/* This is similar to png_text_compress, above, except that it does not require
+ * all of the data at once and, instead of buffering the compressed result,
+ * writes it as IDAT chunks.  Unlike png_text_compress it *can* png_error out
+ * because it calls the write interface.  As a result it does its own error
+ * reporting and does not return an error code.  In the event of error it will
+ * just call png_error.  The input data length may exceed 32-bits.  The 'flush'
+ * parameter is exactly the same as that to deflate, with the following
+ * meanings:
+ *
+ * Z_NO_FLUSH: normal incremental output of compressed data
+ * Z_SYNC_FLUSH: do a SYNC_FLUSH, used by png_write_flush
+ * Z_FINISH: this is the end of the input, do a Z_FINISH and clean up
+ *
+ * The routine manages the acquire and release of the png_ptr->zstream by
+ * checking and (at the end) clearing png_ptr->zowner; it does some sanity
+ * checks on the 'mode' flags while doing this.
+ */
 void /* PRIVATE */
-png_write_IDAT(png_structp png_ptr, png_bytep data, png_size_t length)
+png_compress_IDAT(png_structrp png_ptr, png_const_bytep input,
+   png_alloc_size_t input_len, int flush)
 {
-   png_debug(1, "in png_write_IDAT");
+   if (png_ptr->zowner != png_IDAT)
+   {
+      /* First time.   Ensure we have a temporary buffer for compression and
+       * trim the buffer list if it has more than one entry to free memory.
+       * If 'WRITE_COMPRESSED_TEXT' is not set the list will never have been
+       * created at this point, but the check here is quick and safe.
+       */
+      if (png_ptr->zbuffer_list == NULL)
+      {
+         png_ptr->zbuffer_list = png_voidcast(png_compression_bufferp,
+            png_malloc(png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr)));
+         png_ptr->zbuffer_list->next = NULL;
+      }
 
-#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
-   if (!(png_ptr->mode & PNG_HAVE_IDAT) &&
-       png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
+      else
+         png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list->next);
+
+      /* It is a terminal error if we can't claim the zstream. */
+      if (png_deflate_claim(png_ptr, png_IDAT, png_image_size(png_ptr)) != Z_OK)
+         png_error(png_ptr, png_ptr->zstream.msg);
+
+      /* The output state is maintained in png_ptr->zstream, so it must be
+       * initialized here after the claim.
+       */
+      png_ptr->zstream.next_out = png_ptr->zbuffer_list->output;
+      png_ptr->zstream.avail_out = png_ptr->zbuffer_size;
+   }
+
+   /* Now loop reading and writing until all the input is consumed or an error
+    * terminates the operation.  The _out values are maintained across calls to
+    * this function, but the input must be reset each time.
+    */
+   png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input);
+   png_ptr->zstream.avail_in = 0; /* set below */
+   for (;;)
    {
-      /* Optimize the CMF field in the zlib stream.  This hack of the zlib
-       * stream is compliant to the stream specification.
+      int ret;
+
+      /* INPUT: from the row data */
+      uInt avail = ZLIB_IO_MAX;
+
+      if (avail > input_len)
+         avail = (uInt)input_len; /* safe because of the check */
+
+      png_ptr->zstream.avail_in = avail;
+      input_len -= avail;
+
+      ret = deflate(&png_ptr->zstream, input_len > 0 ? Z_NO_FLUSH : flush);
+
+      /* Include as-yet unconsumed input */
+      input_len += png_ptr->zstream.avail_in;
+      png_ptr->zstream.avail_in = 0;
+
+      /* OUTPUT: write complete IDAT chunks when avail_out drops to zero. Note
+       * that these two zstream fields are preserved across the calls, therefore
+       * there is no need to set these up on entry to the loop.
        */
-      unsigned int z_cmf = data[0];  /* zlib compression method and flags */
+      if (png_ptr->zstream.avail_out == 0)
+      {
+         png_bytep data = png_ptr->zbuffer_list->output;
+         uInt size = png_ptr->zbuffer_size;
 
-      if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
+         /* Write an IDAT containing the data then reset the buffer.  The
+          * first IDAT may need deflate header optimization.
+          */
+#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
+            if ((png_ptr->mode & PNG_HAVE_IDAT) == 0 &&
+                png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
+               optimize_cmf(data, png_image_size(png_ptr));
+#endif
+
+         png_write_complete_chunk(png_ptr, png_IDAT, data, size);
+         png_ptr->mode |= PNG_HAVE_IDAT;
+
+         png_ptr->zstream.next_out = data;
+         png_ptr->zstream.avail_out = size;
+
+         /* For SYNC_FLUSH or FINISH it is essential to keep calling zlib with
+          * the same flush parameter until it has finished output, for NO_FLUSH
+          * it doesn't matter.
+          */
+         if (ret == Z_OK && flush != Z_NO_FLUSH)
+            continue;
+      }
+
+      /* The order of these checks doesn't matter much; it just affects which
+       * possible error might be detected if multiple things go wrong at once.
+       */
+      if (ret == Z_OK) /* most likely return code! */
       {
-         /* Avoid memory underflows and multiplication overflows.
-          *
-          * The conditions below are practically always satisfied;
-          * however, they still must be checked.
+         /* If all the input has been consumed then just return.  If Z_FINISH
+          * was used as the flush parameter something has gone wrong if we get
+          * here.
           */
-         if (length >= 2 &&
-             png_ptr->height < 16384 && png_ptr->width < 16384)
+         if (input_len == 0)
          {
-            /* Compute the maximum possible length of the datastream */
+            if (flush == Z_FINISH)
+               png_error(png_ptr, "Z_OK on Z_FINISH with output space");
 
-            /* Number of pixels, plus for each row a filter byte
-             * and possibly a padding byte, so increase the maximum
-             * size to account for these.
-             */
-            unsigned int z_cinfo;
-            unsigned int half_z_window_size;
-            png_uint_32 uncompressed_idat_size = png_ptr->height *
-                ((png_ptr->width *
-                png_ptr->channels * png_ptr->bit_depth + 15) >> 3);
-
-            /* If it's interlaced, each block of 8 rows is sent as up to
-             * 14 rows, i.e., 6 additional rows, each with a filter byte
-             * and possibly a padding byte
-             */
-            if (png_ptr->interlaced)
-               uncompressed_idat_size += ((png_ptr->height + 7)/8) *
-                   (png_ptr->bit_depth < 8 ? 12 : 6);
+            return;
+         }
+      }
 
-            z_cinfo = z_cmf >> 4;
-            half_z_window_size = 1 << (z_cinfo + 7);
+      else if (ret == Z_STREAM_END && flush == Z_FINISH)
+      {
+         /* This is the end of the IDAT data; any pending output must be
+          * flushed.  For small PNG files we may still be at the beginning.
+          */
+         png_bytep data = png_ptr->zbuffer_list->output;
+         uInt size = png_ptr->zbuffer_size - png_ptr->zstream.avail_out;
 
-            while (uncompressed_idat_size <= half_z_window_size &&
-                half_z_window_size >= 256)
-            {
-               z_cinfo--;
-               half_z_window_size >>= 1;
-            }
+#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
+         if ((png_ptr->mode & PNG_HAVE_IDAT) == 0 &&
+             png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
+            optimize_cmf(data, png_image_size(png_ptr));
+#endif
 
-            z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
+         png_write_complete_chunk(png_ptr, png_IDAT, data, size);
+         png_ptr->zstream.avail_out = 0;
+         png_ptr->zstream.next_out = NULL;
+         png_ptr->mode |= PNG_HAVE_IDAT | PNG_AFTER_IDAT;
 
-            if (data[0] != z_cmf)
-            {
-               int tmp;
-               data[0] = (png_byte)z_cmf;
-               tmp = data[1] & 0xe0;
-               tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
-               data[1] = (png_byte)tmp;
-            }
-         }
+         png_ptr->zowner = 0; /* Release the stream */
+         return;
       }
 
       else
-         png_error(png_ptr,
-             "Invalid zlib compression method or flags in IDAT");
+      {
+         /* This is an error condition. */
+         png_zstream_error(png_ptr, ret);
+         png_error(png_ptr, png_ptr->zstream.msg);
+      }
    }
-#endif /* PNG_WRITE_OPTIMIZE_CMF_SUPPORTED */
-
-   png_write_complete_chunk(png_ptr, png_IDAT, data, length);
-   png_ptr->mode |= PNG_HAVE_IDAT;
-
-   /* Prior to 1.5.4 this code was replicated in every caller (except at the
-    * end, where it isn't technically necessary).  Since this function has
-    * flushed the data we can safely reset the zlib output buffer here.
-    */
-   png_ptr->zstream.next_out = png_ptr->zbuf;
-   png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
 }
 
 /* Write an IEND chunk */
 void /* PRIVATE */
-png_write_IEND(png_structp png_ptr)
+png_write_IEND(png_structrp png_ptr)
 {
    png_debug(1, "in png_write_IEND");
 
@@ -1059,7 +1156,7 @@ png_write_IEND(png_structp png_ptr)
 #ifdef PNG_WRITE_gAMA_SUPPORTED
 /* Write a gAMA chunk */
 void /* PRIVATE */
-png_write_gAMA_fixed(png_structp png_ptr, png_fixed_point file_gamma)
+png_write_gAMA_fixed(png_structrp png_ptr, png_fixed_point file_gamma)
 {
    png_byte buf[4];
 
@@ -1074,7 +1171,7 @@ png_write_gAMA_fixed(png_structp png_ptr, png_fixed_point file_gamma)
 #ifdef PNG_WRITE_sRGB_SUPPORTED
 /* Write a sRGB chunk */
 void /* PRIVATE */
-png_write_sRGB(png_structp png_ptr, int srgb_intent)
+png_write_sRGB(png_structrp png_ptr, int srgb_intent)
 {
    png_byte buf[1];
 
@@ -1092,94 +1189,72 @@ png_write_sRGB(png_structp png_ptr, int srgb_intent)
 #ifdef PNG_WRITE_iCCP_SUPPORTED
 /* Write an iCCP chunk */
 void /* PRIVATE */
-png_write_iCCP(png_structp png_ptr, png_const_charp name, int compression_type,
-    png_const_charp profile, int profile_len)
+png_write_iCCP(png_structrp png_ptr, png_const_charp name,
+    png_const_bytep profile)
 {
-   png_size_t name_len;
-   png_charp new_name;
+   png_uint_32 name_len;
+   png_uint_32 profile_len;
+   png_byte new_name[81]; /* 1 byte for the compression byte */
    compression_state comp;
-   int embedded_profile_len = 0;
+   png_uint_32 temp;
 
    png_debug(1, "in png_write_iCCP");
 
-   comp.num_output_ptr = 0;
-   comp.max_output_ptr = 0;
-   comp.output_ptr = NULL;
-   comp.input = NULL;
-   comp.input_len = 0;
-
-   if ((name_len = png_check_keyword(png_ptr, name, &new_name)) == 0)
-      return;
-
-   if (compression_type != PNG_COMPRESSION_TYPE_BASE)
-      png_warning(png_ptr, "Unknown compression type in iCCP chunk");
-
+   /* These are all internal problems: the profile should have been checked
+    * before when it was stored.
+    */
    if (profile == NULL)
-      profile_len = 0;
+      png_error(png_ptr, "No profile for iCCP chunk"); /* internal error */
 
-   if (profile_len > 3)
-      embedded_profile_len =
-          ((*( (png_const_bytep)profile    ))<<24) |
-          ((*( (png_const_bytep)profile + 1))<<16) |
-          ((*( (png_const_bytep)profile + 2))<< 8) |
-          ((*( (png_const_bytep)profile + 3))    );
+   profile_len = png_get_uint_32(profile);
 
-   if (embedded_profile_len < 0)
-   {
-      png_warning(png_ptr,
-          "Embedded profile length in iCCP chunk is negative");
+   if (profile_len < 132)
+      png_error(png_ptr, "ICC profile too short");
 
-      png_free(png_ptr, new_name);
-      return;
-   }
+   temp = (png_uint_32) (*(profile+8));
+   if (temp > 3 && (profile_len & 0x03))
+      png_error(png_ptr, "ICC profile length invalid (not a multiple of 4)");
 
-   if (profile_len < embedded_profile_len)
    {
-      png_warning(png_ptr,
-          "Embedded profile length too large in iCCP chunk");
+      png_uint_32 embedded_profile_len = png_get_uint_32(profile);
 
-      png_free(png_ptr, new_name);
-      return;
+      if (profile_len != embedded_profile_len)
+         png_error(png_ptr, "Profile length does not match profile");
    }
 
-   if (profile_len > embedded_profile_len)
-   {
-      png_warning(png_ptr,
-          "Truncating profile to actual length in iCCP chunk");
+   name_len = png_check_keyword(png_ptr, name, new_name);
 
-      profile_len = embedded_profile_len;
-   }
+   if (name_len == 0)
+      png_error(png_ptr, "iCCP: invalid keyword");
 
-   if (profile_len)
-      profile_len = png_text_compress(png_ptr, profile,
-          (png_size_t)profile_len, PNG_COMPRESSION_TYPE_BASE, &comp);
+   new_name[++name_len] = PNG_COMPRESSION_TYPE_BASE;
 
    /* Make sure we include the NULL after the name and the compression type */
-   png_write_chunk_header(png_ptr, png_iCCP,
-       (png_uint_32)(name_len + profile_len + 2));
+   ++name_len;
 
-   new_name[name_len + 1] = 0x00;
+   png_text_compress_init(&comp, profile, profile_len);
 
-   png_write_chunk_data(png_ptr, (png_bytep)new_name,
-       (png_size_t)(name_len + 2));
+   /* Allow for keyword terminator and compression byte */
+   if (png_text_compress(png_ptr, png_iCCP, &comp, name_len) != Z_OK)
+      png_error(png_ptr, png_ptr->zstream.msg);
 
-   if (profile_len)
-   {
-      png_write_compressed_data_out(png_ptr, &comp, profile_len);
-   }
+   png_write_chunk_header(png_ptr, png_iCCP, name_len + comp.output_len);
+
+   png_write_chunk_data(png_ptr, new_name, name_len);
+
+   png_write_compressed_data_out(png_ptr, &comp);
 
    png_write_chunk_end(png_ptr);
-   png_free(png_ptr, new_name);
 }
 #endif
 
 #ifdef PNG_WRITE_sPLT_SUPPORTED
 /* Write a sPLT chunk */
 void /* PRIVATE */
-png_write_sPLT(png_structp png_ptr, png_const_sPLT_tp spalette)
+png_write_sPLT(png_structrp png_ptr, png_const_sPLT_tp spalette)
 {
-   png_size_t name_len;
-   png_charp new_name;
+   png_uint_32 name_len;
+   png_byte new_name[80];
    png_byte entrybuf[10];
    png_size_t entry_size = (spalette->depth == 8 ? 6 : 10);
    png_size_t palette_size = entry_size * spalette->nentries;
@@ -1190,8 +1265,10 @@ png_write_sPLT(png_structp png_ptr, png_const_sPLT_tp spalette)
 
    png_debug(1, "in png_write_sPLT");
 
-   if ((name_len = png_check_keyword(png_ptr,spalette->name, &new_name))==0)
-      return;
+   name_len = png_check_keyword(png_ptr, spalette->name, new_name);
+
+   if (name_len == 0)
+      png_error(png_ptr, "sPLT: invalid keyword");
 
    /* Make sure we include the NULL after the name */
    png_write_chunk_header(png_ptr, png_sPLT,
@@ -1224,7 +1301,7 @@ png_write_sPLT(png_structp png_ptr, png_const_sPLT_tp spalette)
          png_save_uint_16(entrybuf + 8, ep->frequency);
       }
 
-      png_write_chunk_data(png_ptr, entrybuf, (png_size_t)entry_size);
+      png_write_chunk_data(png_ptr, entrybuf, entry_size);
    }
 #else
    ep=spalette->entries;
@@ -1248,19 +1325,18 @@ png_write_sPLT(png_structp png_ptr, png_const_sPLT_tp spalette)
          png_save_uint_16(entrybuf + 8, ep[i].frequency);
       }
 
-      png_write_chunk_data(png_ptr, entrybuf, (png_size_t)entry_size);
+      png_write_chunk_data(png_ptr, entrybuf, entry_size);
    }
 #endif
 
    png_write_chunk_end(png_ptr);
-   png_free(png_ptr, new_name);
 }
 #endif
 
 #ifdef PNG_WRITE_sBIT_SUPPORTED
 /* Write the sBIT chunk */
 void /* PRIVATE */
-png_write_sBIT(png_structp png_ptr, png_const_color_8p sbit, int color_type)
+png_write_sBIT(png_structrp png_ptr, png_const_color_8p sbit, int color_type)
 {
    png_byte buf[4];
    png_size_t size;
@@ -1268,7 +1344,7 @@ png_write_sBIT(png_structp png_ptr, png_const_color_8p sbit, int color_type)
    png_debug(1, "in png_write_sBIT");
 
    /* Make sure we don't depend upon the order of PNG_COLOR_8 */
-   if (color_type & PNG_COLOR_MASK_COLOR)
+   if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
    {
       png_byte maxbits;
 
@@ -1301,7 +1377,7 @@ png_write_sBIT(png_structp png_ptr, png_const_color_8p sbit, int color_type)
       size = 1;
    }
 
-   if (color_type & PNG_COLOR_MASK_ALPHA)
+   if ((color_type & PNG_COLOR_MASK_ALPHA) != 0)
    {
       if (sbit->alpha == 0 || sbit->alpha > png_ptr->usr_bit_depth)
       {
@@ -1319,42 +1395,33 @@ png_write_sBIT(png_structp png_ptr, png_const_color_8p sbit, int color_type)
 #ifdef PNG_WRITE_cHRM_SUPPORTED
 /* Write the cHRM chunk */
 void /* PRIVATE */
-png_write_cHRM_fixed(png_structp png_ptr, png_fixed_point white_x,
-    png_fixed_point white_y, png_fixed_point red_x, png_fixed_point red_y,
-    png_fixed_point green_x, png_fixed_point green_y, png_fixed_point blue_x,
-    png_fixed_point blue_y)
+png_write_cHRM_fixed(png_structrp png_ptr, const png_xy *xy)
 {
    png_byte buf[32];
 
    png_debug(1, "in png_write_cHRM");
 
    /* Each value is saved in 1/100,000ths */
-#ifdef PNG_CHECK_cHRM_SUPPORTED
-   if (png_check_cHRM_fixed(png_ptr, white_x, white_y, red_x, red_y,
-       green_x, green_y, blue_x, blue_y))
-#endif
-   {
-      png_save_uint_32(buf, (png_uint_32)white_x);
-      png_save_uint_32(buf + 4, (png_uint_32)white_y);
+   png_save_int_32(buf,      xy->whitex);
+   png_save_int_32(buf +  4, xy->whitey);
 
-      png_save_uint_32(buf + 8, (png_uint_32)red_x);
-      png_save_uint_32(buf + 12, (png_uint_32)red_y);
+   png_save_int_32(buf +  8, xy->redx);
+   png_save_int_32(buf + 12, xy->redy);
 
-      png_save_uint_32(buf + 16, (png_uint_32)green_x);
-      png_save_uint_32(buf + 20, (png_uint_32)green_y);
+   png_save_int_32(buf + 16, xy->greenx);
+   png_save_int_32(buf + 20, xy->greeny);
 
-      png_save_uint_32(buf + 24, (png_uint_32)blue_x);
-      png_save_uint_32(buf + 28, (png_uint_32)blue_y);
+   png_save_int_32(buf + 24, xy->bluex);
+   png_save_int_32(buf + 28, xy->bluey);
 
-      png_write_complete_chunk(png_ptr, png_cHRM, buf, (png_size_t)32);
-   }
+   png_write_complete_chunk(png_ptr, png_cHRM, buf, 32);
 }
 #endif
 
 #ifdef PNG_WRITE_tRNS_SUPPORTED
 /* Write the tRNS chunk */
 void /* PRIVATE */
-png_write_tRNS(png_structp png_ptr, png_const_bytep trans_alpha,
+png_write_tRNS(png_structrp png_ptr, png_const_bytep trans_alpha,
     png_const_color_16p tran, int num_trans, int color_type)
 {
    png_byte buf[6];
@@ -1365,12 +1432,14 @@ png_write_tRNS(png_structp png_ptr, png_const_bytep trans_alpha,
    {
       if (num_trans <= 0 || num_trans > (int)png_ptr->num_palette)
       {
-         png_warning(png_ptr, "Invalid number of transparent colors specified");
+         png_app_warning(png_ptr,
+             "Invalid number of transparent colors specified");
          return;
       }
 
       /* Write the chunk out as it is */
-      png_write_complete_chunk(png_ptr, png_tRNS, trans_alpha, (png_size_t)num_trans);
+      png_write_complete_chunk(png_ptr, png_tRNS, trans_alpha,
+         (png_size_t)num_trans);
    }
 
    else if (color_type == PNG_COLOR_TYPE_GRAY)
@@ -1378,7 +1447,7 @@ png_write_tRNS(png_structp png_ptr, png_const_bytep trans_alpha,
       /* One 16 bit value */
       if (tran->gray >= (1 << png_ptr->bit_depth))
       {
-         png_warning(png_ptr,
+         png_app_warning(png_ptr,
              "Ignoring attempt to write tRNS chunk out-of-range for bit_depth");
 
          return;
@@ -1395,12 +1464,12 @@ png_write_tRNS(png_structp png_ptr, png_const_bytep trans_alpha,
       png_save_uint_16(buf + 2, tran->green);
       png_save_uint_16(buf + 4, tran->blue);
 #ifdef PNG_WRITE_16BIT_SUPPORTED
-      if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]))
+      if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]) != 0)
 #else
-      if (buf[0] | buf[2] | buf[4])
+      if ((buf[0] | buf[2] | buf[4]) != 0)
 #endif
       {
-         png_warning(png_ptr,
+         png_app_warning(png_ptr,
            "Ignoring attempt to write 16-bit tRNS chunk when bit_depth is 8");
          return;
       }
@@ -1410,7 +1479,7 @@ png_write_tRNS(png_structp png_ptr, png_const_bytep trans_alpha,
 
    else
    {
-      png_warning(png_ptr, "Can't write tRNS with an alpha channel");
+      png_app_warning(png_ptr, "Can't write tRNS with an alpha channel");
    }
 }
 #endif
@@ -1418,7 +1487,7 @@ png_write_tRNS(png_structp png_ptr, png_const_bytep trans_alpha,
 #ifdef PNG_WRITE_bKGD_SUPPORTED
 /* Write the background chunk */
 void /* PRIVATE */
-png_write_bKGD(png_structp png_ptr, png_const_color_16p back, int color_type)
+png_write_bKGD(png_structrp png_ptr, png_const_color_16p back, int color_type)
 {
    png_byte buf[6];
 
@@ -1428,8 +1497,8 @@ png_write_bKGD(png_structp png_ptr, png_const_color_16p back, int color_type)
    {
       if (
 #ifdef PNG_MNG_FEATURES_SUPPORTED
-          (png_ptr->num_palette ||
-          (!(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE))) &&
+          (png_ptr->num_palette != 0 ||
+          (png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0) &&
 #endif
          back->index >= png_ptr->num_palette)
       {
@@ -1441,15 +1510,15 @@ png_write_bKGD(png_structp png_ptr, png_const_color_16p back, int color_type)
       png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)1);
    }
 
-   else if (color_type & PNG_COLOR_MASK_COLOR)
+   else if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
    {
       png_save_uint_16(buf, back->red);
       png_save_uint_16(buf + 2, back->green);
       png_save_uint_16(buf + 4, back->blue);
 #ifdef PNG_WRITE_16BIT_SUPPORTED
-      if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]))
+      if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]) != 0)
 #else
-      if (buf[0] | buf[2] | buf[4])
+      if ((buf[0] | buf[2] | buf[4]) != 0)
 #endif
       {
          png_warning(png_ptr,
@@ -1480,7 +1549,7 @@ png_write_bKGD(png_structp png_ptr, png_const_color_16p back, int color_type)
 #ifdef PNG_WRITE_hIST_SUPPORTED
 /* Write the histogram */
 void /* PRIVATE */
-png_write_hIST(png_structp png_ptr, png_const_uint_16p hist, int num_hist)
+png_write_hIST(png_structrp png_ptr, png_const_uint_16p hist, int num_hist)
 {
    int i;
    png_byte buf[3];
@@ -1508,234 +1577,94 @@ png_write_hIST(png_structp png_ptr, png_const_uint_16p hist, int num_hist)
 }
 #endif
 
-#if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_pCAL_SUPPORTED) || \
-    defined(PNG_WRITE_iCCP_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
-/* Check that the tEXt or zTXt keyword is valid per PNG 1.0 specification,
- * and if invalid, correct the keyword rather than discarding the entire
- * chunk.  The PNG 1.0 specification requires keywords 1-79 characters in
- * length, forbids leading or trailing whitespace, multiple internal spaces,
- * and the non-break space (0x80) from ISO 8859-1.  Returns keyword length.
- *
- * The new_key is allocated to hold the corrected keyword and must be freed
- * by the calling routine.  This avoids problems with trying to write to
- * static keywords without having to have duplicate copies of the strings.
- */
-png_size_t /* PRIVATE */
-png_check_keyword(png_structp png_ptr, png_const_charp key, png_charpp new_key)
-{
-   png_size_t key_len;
-   png_const_charp ikp;
-   png_charp kp, dp;
-   int kflag;
-   int kwarn=0;
-
-   png_debug(1, "in png_check_keyword");
-
-   *new_key = NULL;
-
-   if (key == NULL || (key_len = png_strlen(key)) == 0)
-   {
-      png_warning(png_ptr, "zero length keyword");
-      return ((png_size_t)0);
-   }
-
-   png_debug1(2, "Keyword to be checked is '%s'", key);
-
-   *new_key = (png_charp)png_malloc_warn(png_ptr, (png_uint_32)(key_len + 2));
-
-   if (*new_key == NULL)
-   {
-      png_warning(png_ptr, "Out of memory while procesing keyword");
-      return ((png_size_t)0);
-   }
-
-   /* Replace non-printing characters with a blank and print a warning */
-   for (ikp = key, dp = *new_key; *ikp != '\0'; ikp++, dp++)
-   {
-      if ((png_byte)*ikp < 0x20 ||
-         ((png_byte)*ikp > 0x7E && (png_byte)*ikp < 0xA1))
-      {
-         PNG_WARNING_PARAMETERS(p)
-
-         png_warning_parameter_unsigned(p, 1, PNG_NUMBER_FORMAT_02x,
-            (png_byte)*ikp);
-         png_formatted_warning(png_ptr, p, "invalid keyword character 0x@1");
-         *dp = ' ';
-      }
-
-      else
-      {
-         *dp = *ikp;
-      }
-   }
-   *dp = '\0';
-
-   /* Remove any trailing white space. */
-   kp = *new_key + key_len - 1;
-   if (*kp == ' ')
-   {
-      png_warning(png_ptr, "trailing spaces removed from keyword");
-
-      while (*kp == ' ')
-      {
-         *(kp--) = '\0';
-         key_len--;
-      }
-   }
-
-   /* Remove any leading white space. */
-   kp = *new_key;
-   if (*kp == ' ')
-   {
-      png_warning(png_ptr, "leading spaces removed from keyword");
-
-      while (*kp == ' ')
-      {
-         kp++;
-         key_len--;
-      }
-   }
-
-   png_debug1(2, "Checking for multiple internal spaces in '%s'", kp);
-
-   /* Remove multiple internal spaces. */
-   for (kflag = 0, dp = *new_key; *kp != '\0'; kp++)
-   {
-      if (*kp == ' ' && kflag == 0)
-      {
-         *(dp++) = *kp;
-         kflag = 1;
-      }
-
-      else if (*kp == ' ')
-      {
-         key_len--;
-         kwarn = 1;
-      }
-
-      else
-      {
-         *(dp++) = *kp;
-         kflag = 0;
-      }
-   }
-   *dp = '\0';
-   if (kwarn)
-      png_warning(png_ptr, "extra interior spaces removed from keyword");
-
-   if (key_len == 0)
-   {
-      png_free(png_ptr, *new_key);
-      png_warning(png_ptr, "Zero length keyword");
-   }
-
-   if (key_len > 79)
-   {
-      png_warning(png_ptr, "keyword length must be 1 - 79 characters");
-      (*new_key)[79] = '\0';
-      key_len = 79;
-   }
-
-   return (key_len);
-}
-#endif
-
 #ifdef PNG_WRITE_tEXt_SUPPORTED
 /* Write a tEXt chunk */
 void /* PRIVATE */
-png_write_tEXt(png_structp png_ptr, png_const_charp key, png_const_charp text,
+png_write_tEXt(png_structrp png_ptr, png_const_charp key, png_const_charp text,
     png_size_t text_len)
 {
-   png_size_t key_len;
-   png_charp new_key;
+   png_uint_32 key_len;
+   png_byte new_key[80];
 
    png_debug(1, "in png_write_tEXt");
 
-   if ((key_len = png_check_keyword(png_ptr, key, &new_key))==0)
-      return;
+   key_len = png_check_keyword(png_ptr, key, new_key);
+
+   if (key_len == 0)
+      png_error(png_ptr, "tEXt: invalid keyword");
 
    if (text == NULL || *text == '\0')
       text_len = 0;
 
    else
-      text_len = png_strlen(text);
+      text_len = strlen(text);
+
+   if (text_len > PNG_UINT_31_MAX - (key_len+1))
+      png_error(png_ptr, "tEXt: text too long");
 
    /* Make sure we include the 0 after the key */
    png_write_chunk_header(png_ptr, png_tEXt,
-       (png_uint_32)(key_len + text_len + 1));
+       (png_uint_32)/*checked above*/(key_len + text_len + 1));
    /*
     * We leave it to the application to meet PNG-1.0 requirements on the
     * contents of the text.  PNG-1.0 through PNG-1.2 discourage the use of
     * any non-Latin-1 characters except for NEWLINE.  ISO PNG will forbid them.
     * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
     */
-   png_write_chunk_data(png_ptr, (png_bytep)new_key,
-       (png_size_t)(key_len + 1));
+   png_write_chunk_data(png_ptr, new_key, key_len + 1);
 
-   if (text_len)
-      png_write_chunk_data(png_ptr, (png_const_bytep)text,
-          (png_size_t)text_len);
+   if (text_len != 0)
+      png_write_chunk_data(png_ptr, (png_const_bytep)text, text_len);
 
    png_write_chunk_end(png_ptr);
-   png_free(png_ptr, new_key);
 }
 #endif
 
 #ifdef PNG_WRITE_zTXt_SUPPORTED
 /* Write a compressed text chunk */
 void /* PRIVATE */
-png_write_zTXt(png_structp png_ptr, png_const_charp key, png_const_charp text,
-    png_size_t text_len, int compression)
+png_write_zTXt(png_structrp png_ptr, png_const_charp key, png_const_charp text,
+    int compression)
 {
-   png_size_t key_len;
-   png_byte buf;
-   png_charp new_key;
+   png_uint_32 key_len;
+   png_byte new_key[81];
    compression_state comp;
 
    png_debug(1, "in png_write_zTXt");
 
-   comp.num_output_ptr = 0;
-   comp.max_output_ptr = 0;
-   comp.output_ptr = NULL;
-   comp.input = NULL;
-   comp.input_len = 0;
-
-   if ((key_len = png_check_keyword(png_ptr, key, &new_key)) == 0)
+   if (compression == PNG_TEXT_COMPRESSION_NONE)
    {
-      png_free(png_ptr, new_key);
+      png_write_tEXt(png_ptr, key, text, 0);
       return;
    }
 
-   if (text == NULL || *text == '\0' || compression==PNG_TEXT_COMPRESSION_NONE)
-   {
-      png_write_tEXt(png_ptr, new_key, text, (png_size_t)0);
-      png_free(png_ptr, new_key);
-      return;
-   }
+   if (compression != PNG_TEXT_COMPRESSION_zTXt)
+      png_error(png_ptr, "zTXt: invalid compression type");
 
-   text_len = png_strlen(text);
+   key_len = png_check_keyword(png_ptr, key, new_key);
 
-   /* Compute the compressed data; do it now for the length */
-   text_len = png_text_compress(png_ptr, text, text_len, compression,
-       &comp);
+   if (key_len == 0)
+      png_error(png_ptr, "zTXt: invalid keyword");
 
-   /* Write start of chunk */
-   png_write_chunk_header(png_ptr, png_zTXt,
-       (png_uint_32)(key_len+text_len + 2));
+   /* Add the compression method and 1 for the keyword separator. */
+   new_key[++key_len] = PNG_COMPRESSION_TYPE_BASE;
+   ++key_len;
 
-   /* Write key */
-   png_write_chunk_data(png_ptr, (png_bytep)new_key,
-       (png_size_t)(key_len + 1));
+   /* Compute the compressed data; do it now for the length */
+   png_text_compress_init(&comp, (png_const_bytep)text,
+      text == NULL ? 0 : strlen(text));
 
-   png_free(png_ptr, new_key);
+   if (png_text_compress(png_ptr, png_zTXt, &comp, key_len) != Z_OK)
+      png_error(png_ptr, png_ptr->zstream.msg);
 
-   buf = (png_byte)compression;
+   /* Write start of chunk */
+   png_write_chunk_header(png_ptr, png_zTXt, key_len + comp.output_len);
 
-   /* Write compression */
-   png_write_chunk_data(png_ptr, &buf, (png_size_t)1);
+   /* Write key */
+   png_write_chunk_data(png_ptr, new_key, key_len);
 
    /* Write the compressed data */
-   png_write_compressed_data_out(png_ptr, &comp, text_len);
+   png_write_compressed_data_out(png_ptr, &comp);
 
    /* Close the chunk */
    png_write_chunk_end(png_ptr);
@@ -1745,100 +1674,107 @@ png_write_zTXt(png_structp png_ptr, png_const_charp key, png_const_charp text,
 #ifdef PNG_WRITE_iTXt_SUPPORTED
 /* Write an iTXt chunk */
 void /* PRIVATE */
-png_write_iTXt(png_structp png_ptr, int compression, png_const_charp key,
+png_write_iTXt(png_structrp png_ptr, int compression, png_const_charp key,
     png_const_charp lang, png_const_charp lang_key, png_const_charp text)
 {
-   png_size_t lang_len, key_len, lang_key_len, text_len;
-   png_charp new_lang;
-   png_charp new_key = NULL;
-   png_byte cbuf[2];
+   png_uint_32 key_len, prefix_len;
+   png_size_t lang_len, lang_key_len;
+   png_byte new_key[82];
    compression_state comp;
 
    png_debug(1, "in png_write_iTXt");
 
-   comp.num_output_ptr = 0;
-   comp.max_output_ptr = 0;
-   comp.output_ptr = NULL;
-   comp.input = NULL;
+   key_len = png_check_keyword(png_ptr, key, new_key);
 
-   if ((key_len = png_check_keyword(png_ptr, key, &new_key)) == 0)
-      return;
+   if (key_len == 0)
+      png_error(png_ptr, "iTXt: invalid keyword");
 
-   if ((lang_len = png_check_keyword(png_ptr, lang, &new_lang)) == 0)
+   /* Set the compression flag */
+   switch (compression)
    {
-      png_warning(png_ptr, "Empty language field in iTXt chunk");
-      new_lang = NULL;
-      lang_len = 0;
-   }
+      case PNG_ITXT_COMPRESSION_NONE:
+      case PNG_TEXT_COMPRESSION_NONE:
+         compression = new_key[++key_len] = 0; /* no compression */
+         break;
 
-   if (lang_key == NULL)
-      lang_key_len = 0;
+      case PNG_TEXT_COMPRESSION_zTXt:
+      case PNG_ITXT_COMPRESSION_zTXt:
+         compression = new_key[++key_len] = 1; /* compressed */
+         break;
 
-   else
-      lang_key_len = png_strlen(lang_key);
+      default:
+         png_error(png_ptr, "iTXt: invalid compression");
+   }
 
-   if (text == NULL)
-      text_len = 0;
+   new_key[++key_len] = PNG_COMPRESSION_TYPE_BASE;
+   ++key_len; /* for the keywod separator */
 
+   /* We leave it to the application to meet PNG-1.0 requirements on the
+    * contents of the text.  PNG-1.0 through PNG-1.2 discourage the use of
+    * any non-Latin-1 characters except for NEWLINE.  ISO PNG, however,
+    * specifies that the text is UTF-8 and this really doesn't require any
+    * checking.
+    *
+    * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
+    *
+    * TODO: validate the language tag correctly (see the spec.)
+    */
+   if (lang == NULL) lang = ""; /* empty language is valid */
+   lang_len = strlen(lang)+1;
+   if (lang_key == NULL) lang_key = ""; /* may be empty */
+   lang_key_len = strlen(lang_key)+1;
+   if (text == NULL) text = ""; /* may be empty */
+
+   prefix_len = key_len;
+   if (lang_len > PNG_UINT_31_MAX-prefix_len)
+      prefix_len = PNG_UINT_31_MAX;
    else
-      text_len = png_strlen(text);
-
-   /* Compute the compressed data; do it now for the length */
-   text_len = png_text_compress(png_ptr, text, text_len, compression - 2,
-       &comp);
+      prefix_len = (png_uint_32)(prefix_len + lang_len);
 
+   if (lang_key_len > PNG_UINT_31_MAX-prefix_len)
+      prefix_len = PNG_UINT_31_MAX;
+   else
+      prefix_len = (png_uint_32)(prefix_len + lang_key_len);
 
-   /* Make sure we include the compression flag, the compression byte,
-    * and the NULs after the key, lang, and lang_key parts
-    */
+   png_text_compress_init(&comp, (png_const_bytep)text, strlen(text));
 
-   png_write_chunk_header(png_ptr, png_iTXt, (png_uint_32)(
-        5 /* comp byte, comp flag, terminators for key, lang and lang_key */
-        + key_len
-        + lang_len
-        + lang_key_len
-        + text_len));
+   if (compression != 0)
+   {
+      if (png_text_compress(png_ptr, png_iTXt, &comp, prefix_len) != Z_OK)
+         png_error(png_ptr, png_ptr->zstream.msg);
+   }
 
-   /* We leave it to the application to meet PNG-1.0 requirements on the
-    * contents of the text.  PNG-1.0 through PNG-1.2 discourage the use of
-    * any non-Latin-1 characters except for NEWLINE.  ISO PNG will forbid them.
-    * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
-    */
-   png_write_chunk_data(png_ptr, (png_bytep)new_key, (png_size_t)(key_len + 1));
+   else
+   {
+      if (comp.input_len > PNG_UINT_31_MAX-prefix_len)
+         png_error(png_ptr, "iTXt: uncompressed text too long");
 
-   /* Set the compression flag */
-   if (compression == PNG_ITXT_COMPRESSION_NONE ||
-       compression == PNG_TEXT_COMPRESSION_NONE)
-      cbuf[0] = 0;
+      /* So the string will fit in a chunk: */
+      comp.output_len = (png_uint_32)/*SAFE*/comp.input_len;
+   }
 
-   else /* compression == PNG_ITXT_COMPRESSION_zTXt */
-      cbuf[0] = 1;
+   png_write_chunk_header(png_ptr, png_iTXt, comp.output_len + prefix_len);
 
-   /* Set the compression method */
-   cbuf[1] = 0;
+   png_write_chunk_data(png_ptr, new_key, key_len);
 
-   png_write_chunk_data(png_ptr, cbuf, (png_size_t)2);
+   png_write_chunk_data(png_ptr, (png_const_bytep)lang, lang_len);
 
-   cbuf[0] = 0;
-   png_write_chunk_data(png_ptr, (new_lang ? (png_const_bytep)new_lang : cbuf),
-       (png_size_t)(lang_len + 1));
+   png_write_chunk_data(png_ptr, (png_const_bytep)lang_key, lang_key_len);
 
-   png_write_chunk_data(png_ptr, (lang_key ? (png_const_bytep)lang_key : cbuf),
-       (png_size_t)(lang_key_len + 1));
+   if (compression != 0)
+      png_write_compressed_data_out(png_ptr, &comp);
 
-   png_write_compressed_data_out(png_ptr, &comp, text_len);
+   else
+      png_write_chunk_data(png_ptr, (png_const_bytep)text, comp.output_len);
 
    png_write_chunk_end(png_ptr);
-
-   png_free(png_ptr, new_key);
-   png_free(png_ptr, new_lang);
 }
 #endif
 
 #ifdef PNG_WRITE_oFFs_SUPPORTED
 /* Write the oFFs chunk */
 void /* PRIVATE */
-png_write_oFFs(png_structp png_ptr, png_int_32 x_offset, png_int_32 y_offset,
+png_write_oFFs(png_structrp png_ptr, png_int_32 x_offset, png_int_32 y_offset,
     int unit_type)
 {
    png_byte buf[9];
@@ -1858,36 +1794,43 @@ png_write_oFFs(png_structp png_ptr, png_int_32 x_offset, png_int_32 y_offset,
 #ifdef PNG_WRITE_pCAL_SUPPORTED
 /* Write the pCAL chunk (described in the PNG extensions document) */
 void /* PRIVATE */
-png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
+png_write_pCAL(png_structrp png_ptr, png_charp purpose, png_int_32 X0,
     png_int_32 X1, int type, int nparams, png_const_charp units,
     png_charpp params)
 {
-   png_size_t purpose_len, units_len, total_len;
+   png_uint_32 purpose_len;
+   png_size_t units_len, total_len;
    png_size_tp params_len;
    png_byte buf[10];
-   png_charp new_purpose;
+   png_byte new_purpose[80];
    int i;
 
    png_debug1(1, "in png_write_pCAL (%d parameters)", nparams);
 
    if (type >= PNG_EQUATION_LAST)
-      png_warning(png_ptr, "Unrecognized equation type for pCAL chunk");
+      png_error(png_ptr, "Unrecognized equation type for pCAL chunk");
+
+   purpose_len = png_check_keyword(png_ptr, purpose, new_purpose);
+
+   if (purpose_len == 0)
+      png_error(png_ptr, "pCAL: invalid keyword");
+
+   ++purpose_len; /* terminator */
 
-   purpose_len = png_check_keyword(png_ptr, purpose, &new_purpose) + 1;
    png_debug1(3, "pCAL purpose length = %d", (int)purpose_len);
-   units_len = png_strlen(units) + (nparams == 0 ? 0 : 1);
+   units_len = strlen(units) + (nparams == 0 ? 0 : 1);
    png_debug1(3, "pCAL units length = %d", (int)units_len);
    total_len = purpose_len + units_len + 10;
 
    params_len = (png_size_tp)png_malloc(png_ptr,
-       (png_alloc_size_t)(nparams * png_sizeof(png_size_t)));
+       (png_alloc_size_t)(nparams * (sizeof (png_size_t))));
 
    /* Find the length of each parameter, making sure we don't count the
     * null terminator for the last parameter.
     */
    for (i = 0; i < nparams; i++)
    {
-      params_len[i] = png_strlen(params[i]) + (i == nparams - 1 ? 0 : 1);
+      params_len[i] = strlen(params[i]) + (i == nparams - 1 ? 0 : 1);
       png_debug2(3, "pCAL parameter %d length = %lu", i,
           (unsigned long)params_len[i]);
       total_len += params_len[i];
@@ -1895,7 +1838,7 @@ png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
 
    png_debug1(3, "pCAL total length = %d", (int)total_len);
    png_write_chunk_header(png_ptr, png_pCAL, (png_uint_32)total_len);
-   png_write_chunk_data(png_ptr, (png_const_bytep)new_purpose, purpose_len);
+   png_write_chunk_data(png_ptr, new_purpose, purpose_len);
    png_save_int_32(buf, X0);
    png_save_int_32(buf + 4, X1);
    buf[8] = (png_byte)type;
@@ -1903,8 +1846,6 @@ png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
    png_write_chunk_data(png_ptr, buf, (png_size_t)10);
    png_write_chunk_data(png_ptr, (png_const_bytep)units, (png_size_t)units_len);
 
-   png_free(png_ptr, new_purpose);
-
    for (i = 0; i < nparams; i++)
    {
       png_write_chunk_data(png_ptr, (png_const_bytep)params[i], params_len[i]);
@@ -1918,7 +1859,7 @@ png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
 #ifdef PNG_WRITE_sCAL_SUPPORTED
 /* Write the sCAL chunk */
 void /* PRIVATE */
-png_write_sCAL_s(png_structp png_ptr, int unit, png_const_charp width,
+png_write_sCAL_s(png_structrp png_ptr, int unit, png_const_charp width,
     png_const_charp height)
 {
    png_byte buf[64];
@@ -1926,8 +1867,8 @@ png_write_sCAL_s(png_structp png_ptr, int unit, png_const_charp width,
 
    png_debug(1, "in png_write_sCAL_s");
 
-   wlen = png_strlen(width);
-   hlen = png_strlen(height);
+   wlen = strlen(width);
+   hlen = strlen(height);
    total_len = wlen + hlen + 2;
 
    if (total_len > 64)
@@ -1937,8 +1878,8 @@ png_write_sCAL_s(png_structp png_ptr, int unit, png_const_charp width,
    }
 
    buf[0] = (png_byte)unit;
-   png_memcpy(buf + 1, width, wlen + 1);      /* Append the '\0' here */
-   png_memcpy(buf + wlen + 2, height, hlen);  /* Do NOT append the '\0' here */
+   memcpy(buf + 1, width, wlen + 1);      /* Append the '\0' here */
+   memcpy(buf + wlen + 2, height, hlen);  /* Do NOT append the '\0' here */
 
    png_debug1(3, "sCAL total length = %u", (unsigned int)total_len);
    png_write_complete_chunk(png_ptr, png_sCAL, buf, total_len);
@@ -1948,7 +1889,7 @@ png_write_sCAL_s(png_structp png_ptr, int unit, png_const_charp width,
 #ifdef PNG_WRITE_pHYs_SUPPORTED
 /* Write the pHYs chunk */
 void /* PRIVATE */
-png_write_pHYs(png_structp png_ptr, png_uint_32 x_pixels_per_unit,
+png_write_pHYs(png_structrp png_ptr, png_uint_32 x_pixels_per_unit,
     png_uint_32 y_pixels_per_unit,
     int unit_type)
 {
@@ -1972,7 +1913,7 @@ png_write_pHYs(png_structp png_ptr, png_uint_32 x_pixels_per_unit,
  * or png_convert_from_time_t(), or fill in the structure yourself.
  */
 void /* PRIVATE */
-png_write_tIME(png_structp png_ptr, png_const_timep mod_time)
+png_write_tIME(png_structrp png_ptr, png_const_timep mod_time)
 {
    png_byte buf[7];
 
@@ -1999,7 +1940,7 @@ png_write_tIME(png_structp png_ptr, png_const_timep mod_time)
 
 /* Initializes the row writing capability of libpng */
 void /* PRIVATE */
-png_write_start_row(png_structp png_ptr)
+png_write_start_row(png_structrp png_ptr)
 {
 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
@@ -2044,12 +1985,13 @@ png_write_start_row(png_structp png_ptr)
    }
 
    /* We only need to keep the previous row if we are using one of these. */
-   if (png_ptr->do_filter & (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH))
+   if ((png_ptr->do_filter &
+      (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH)) != 0)
    {
       /* Set up previous row buffer */
       png_ptr->prev_row = (png_bytep)png_calloc(png_ptr, buf_size);
 
-      if (png_ptr->do_filter & PNG_FILTER_UP)
+      if ((png_ptr->do_filter & PNG_FILTER_UP) != 0)
       {
          png_ptr->up_row = (png_bytep)png_malloc(png_ptr,
             png_ptr->rowbytes + 1);
@@ -2057,7 +1999,7 @@ png_write_start_row(png_structp png_ptr)
          png_ptr->up_row[0] = PNG_FILTER_VALUE_UP;
       }
 
-      if (png_ptr->do_filter & PNG_FILTER_AVG)
+      if ((png_ptr->do_filter & PNG_FILTER_AVG) != 0)
       {
          png_ptr->avg_row = (png_bytep)png_malloc(png_ptr,
              png_ptr->rowbytes + 1);
@@ -2065,7 +2007,7 @@ png_write_start_row(png_structp png_ptr)
          png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG;
       }
 
-      if (png_ptr->do_filter & PNG_FILTER_PAETH)
+      if ((png_ptr->do_filter & PNG_FILTER_PAETH) != 0)
       {
          png_ptr->paeth_row = (png_bytep)png_malloc(png_ptr,
              png_ptr->rowbytes + 1);
@@ -2073,13 +2015,13 @@ png_write_start_row(png_structp png_ptr)
          png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH;
       }
    }
-#endif /* PNG_WRITE_FILTER_SUPPORTED */
+#endif /* WRITE_FILTER */
 
 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
    /* If interlaced, we need to set up width and height of pass */
-   if (png_ptr->interlaced)
+   if (png_ptr->interlaced != 0)
    {
-      if (!(png_ptr->transformations & PNG_INTERLACE))
+      if ((png_ptr->transformations & PNG_INTERLACE) == 0)
       {
          png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
              png_pass_ystart[0]) / png_pass_yinc[0];
@@ -2101,15 +2043,11 @@ png_write_start_row(png_structp png_ptr)
       png_ptr->num_rows = png_ptr->height;
       png_ptr->usr_width = png_ptr->width;
    }
-
-   png_zlib_claim(png_ptr, PNG_ZLIB_FOR_IDAT);
-   png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
-   png_ptr->zstream.next_out = png_ptr->zbuf;
 }
 
 /* Internal use only.  Called when finished processing a row of data. */
 void /* PRIVATE */
-png_write_finish_row(png_structp png_ptr)
+png_write_finish_row(png_structrp png_ptr)
 {
 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
@@ -2127,8 +2065,6 @@ png_write_finish_row(png_structp png_ptr)
    static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
 #endif
 
-   int ret;
-
    png_debug(1, "in png_write_finish_row");
 
    /* Next row */
@@ -2140,10 +2076,10 @@ png_write_finish_row(png_structp png_ptr)
 
 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
    /* If interlaced, go to next pass */
-   if (png_ptr->interlaced)
+   if (png_ptr->interlaced != 0)
    {
       png_ptr->row_number = 0;
-      if (png_ptr->transformations & PNG_INTERLACE)
+      if ((png_ptr->transformations & PNG_INTERLACE) != 0)
       {
          png_ptr->pass++;
       }
@@ -2168,7 +2104,7 @@ png_write_finish_row(png_structp png_ptr)
                 png_pass_ystart[png_ptr->pass]) /
                 png_pass_yinc[png_ptr->pass];
 
-            if (png_ptr->transformations & PNG_INTERLACE)
+            if ((png_ptr->transformations & PNG_INTERLACE) != 0)
                break;
 
          } while (png_ptr->usr_width == 0 || png_ptr->num_rows == 0);
@@ -2179,7 +2115,7 @@ png_write_finish_row(png_structp png_ptr)
       if (png_ptr->pass < 7)
       {
          if (png_ptr->prev_row != NULL)
-            png_memset(png_ptr->prev_row, 0,
+            memset(png_ptr->prev_row, 0,
                 (png_size_t)(PNG_ROWBYTES(png_ptr->usr_channels*
                 png_ptr->usr_bit_depth, png_ptr->width)) + 1);
 
@@ -2190,42 +2126,7 @@ png_write_finish_row(png_structp png_ptr)
 
    /* If we get here, we've just written the last row, so we need
       to flush the compressor */
-   do
-   {
-      /* Tell the compressor we are done */
-      ret = deflate(&png_ptr->zstream, Z_FINISH);
-
-      /* Check for an error */
-      if (ret == Z_OK)
-      {
-         /* Check to see if we need more room */
-         if (!(png_ptr->zstream.avail_out))
-         {
-            png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
-            png_ptr->zstream.next_out = png_ptr->zbuf;
-            png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
-         }
-      }
-
-      else if (ret != Z_STREAM_END)
-      {
-         if (png_ptr->zstream.msg != NULL)
-            png_error(png_ptr, png_ptr->zstream.msg);
-
-         else
-            png_error(png_ptr, "zlib error");
-      }
-   } while (ret != Z_STREAM_END);
-
-   /* Write any extra space */
-   if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
-   {
-      png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size -
-          png_ptr->zstream.avail_out);
-   }
-
-   png_zlib_release(png_ptr);
-   png_ptr->zstream.data_type = Z_BINARY;
+   png_compress_IDAT(png_ptr, NULL, 0, Z_FINISH);
 }
 
 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
@@ -2389,7 +2290,7 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
 
                /* Move the pixel */
                if (dp != sp)
-                  png_memcpy(dp, sp, pixel_bytes);
+                  memcpy(dp, sp, pixel_bytes);
 
                /* Next pixel */
                dp += pixel_bytes;
@@ -2413,7 +2314,8 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
  * been specified by the application, and then writes the row out with the
  * chosen filter.
  */
-static void png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row,
+static void /* PRIVATE */
+png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row,
    png_size_t row_bytes);
 
 #define PNG_MAXSUM (((png_uint_32)(-1)) >> 1)
@@ -2421,7 +2323,7 @@ static void png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row,
 #define PNG_LOMASK ((png_uint_32)0xffffL)
 #define PNG_HIMASK ((png_uint_32)(~PNG_LOMASK >> PNG_HISHIFT))
 void /* PRIVATE */
-png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
+png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
 {
    png_bytep best_row;
 #ifdef PNG_WRITE_FILTER_SUPPORTED
@@ -2481,7 +2383,7 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
    /* We don't need to test the 'no filter' case if this is the only filter
     * that has been chosen, as it doesn't actually do anything to the data.
     */
-   if ((filter_to_do & PNG_FILTER_NONE) && filter_to_do != PNG_FILTER_NONE)
+   if ((filter_to_do & PNG_FILTER_NONE) != 0 && filter_to_do != PNG_FILTER_NONE)
    {
       png_bytep rp;
       png_uint_32 sum = 0;
@@ -2551,13 +2453,13 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
       for (lp = row_buf + 1; i < row_bytes;
          i++, rp++, lp++, dp++)
       {
-         *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
+         *dp = (png_byte)((int)*rp - (int)*lp);
       }
 
       best_row = png_ptr->sub_row;
    }
 
-   else if (filter_to_do & PNG_FILTER_SUB)
+   else if ((filter_to_do & PNG_FILTER_SUB) != 0)
    {
       png_bytep rp, dp, lp;
       png_uint_32 sum = 0, lmins = mins;
@@ -2613,7 +2515,7 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
       for (lp = row_buf + 1; i < row_bytes;
          i++, rp++, lp++, dp++)
       {
-         v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
+         v = *dp = (png_byte)((int)*rp - (int)*lp);
 
          sum += (v < 128) ? v : 256 - v;
 
@@ -2672,13 +2574,13 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
           pp = prev_row + 1; i < row_bytes;
           i++, rp++, pp++, dp++)
       {
-         *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
+         *dp = (png_byte)((int)*rp - (int)*pp);
       }
 
       best_row = png_ptr->up_row;
    }
 
-   else if (filter_to_do & PNG_FILTER_UP)
+   else if ((filter_to_do & PNG_FILTER_UP) != 0)
    {
       png_bytep rp, dp, pp;
       png_uint_32 sum = 0, lmins = mins;
@@ -2723,7 +2625,7 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
       for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
           pp = prev_row + 1; i < row_bytes; i++)
       {
-         v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
+         v = *dp++ = (png_byte)((int)*rp++ - (int)*pp++);
 
          sum += (v < 128) ? v : 256 - v;
 
@@ -2781,18 +2683,18 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
       for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
            pp = prev_row + 1; i < bpp; i++)
       {
-         *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
+         *dp++ = (png_byte)((int)*rp++ - ((int)*pp++ / 2));
       }
 
       for (lp = row_buf + 1; i < row_bytes; i++)
       {
-         *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2))
-                 & 0xff);
+         *dp++ =
+             (png_byte)((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2));
       }
       best_row = png_ptr->avg_row;
    }
 
-   else if (filter_to_do & PNG_FILTER_AVG)
+   else if ((filter_to_do & PNG_FILTER_AVG) != 0)
    {
       png_bytep rp, dp, pp, lp;
       png_uint_32 sum = 0, lmins = mins;
@@ -2836,7 +2738,7 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
       for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
            pp = prev_row + 1; i < bpp; i++)
       {
-         v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
+         v = *dp++ = (png_byte)((int)*rp++ - ((int)*pp++ / 2));
 
          sum += (v < 128) ? v : 256 - v;
       }
@@ -2844,7 +2746,7 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
       for (lp = row_buf + 1; i < row_bytes; i++)
       {
          v = *dp++ =
-             (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2)) & 0xff);
+             (png_byte)(((int)*rp++ - ((int)*pp++ + (int)*lp++) / 2));
 
          sum += (v < 128) ? v : 256 - v;
 
@@ -2894,7 +2796,7 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
    }
 
    /* Paeth filter */
-   if (filter_to_do == PNG_FILTER_PAETH)
+   if ((filter_to_do == PNG_FILTER_PAETH) != 0)
    {
       png_bytep rp, dp, pp, cp, lp;
       png_size_t i;
@@ -2902,7 +2804,7 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
       for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
           pp = prev_row + 1; i < bpp; i++)
       {
-         *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
+         *dp++ = (png_byte)((int)*rp++ - (int)*pp++);
       }
 
       for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
@@ -2928,12 +2830,12 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
 
          p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
 
-         *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
+         *dp++ = (png_byte)((int)*rp++ - p);
       }
       best_row = png_ptr->paeth_row;
    }
 
-   else if (filter_to_do & PNG_FILTER_PAETH)
+   else if ((filter_to_do & PNG_FILTER_PAETH) != 0)
    {
       png_bytep rp, dp, pp, cp, lp;
       png_uint_32 sum = 0, lmins = mins;
@@ -2977,7 +2879,7 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
       for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
           pp = prev_row + 1; i < bpp; i++)
       {
-         v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
+         v = *dp++ = (png_byte)((int)*rp++ - (int)*pp++);
 
          sum += (v < 128) ? v : 256 - v;
       }
@@ -3003,7 +2905,7 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
          pc = (p + pc) < 0 ? -(p + pc) : p + pc;
 #endif
          p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
-#else /* PNG_SLOW_PAETH */
+#else /* SLOW_PAETH */
          p = a + b - c;
          pa = abs(p - a);
          pb = abs(p - b);
@@ -3017,9 +2919,9 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
 
          else
             p = c;
-#endif /* PNG_SLOW_PAETH */
+#endif /* SLOW_PAETH */
 
-         v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
+         v = *dp++ = (png_byte)((int)*rp++ - p);
 
          sum += (v < 128) ? v : 256 - v;
 
@@ -3066,7 +2968,7 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
          best_row = png_ptr->paeth_row;
       }
    }
-#endif /* PNG_WRITE_FILTER_SUPPORTED */
+#endif /* WRITE_FILTER */
 
    /* Do the actual writing of the filtered row data from the chosen filter. */
    png_write_filtered_row(png_ptr, best_row, row_info->rowbytes+1);
@@ -3086,73 +2988,22 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
       png_ptr->prev_filters[j] = best_row[0];
    }
 #endif
-#endif /* PNG_WRITE_FILTER_SUPPORTED */
+#endif /* WRITE_FILTER */
 }
 
 
 /* Do the actual writing of a previously filtered row. */
 static void
-png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row,
-   png_size_t avail/*includes filter byte*/)
+png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row,
+   png_size_t full_row_length/*includes filter byte*/)
 {
    png_debug(1, "in png_write_filtered_row");
 
    png_debug1(2, "filter = %d", filtered_row[0]);
-   /* Set up the zlib input buffer */
-
-   png_ptr->zstream.next_in = filtered_row;
-   png_ptr->zstream.avail_in = 0;
-   /* Repeat until we have compressed all the data */
-   do
-   {
-      int ret; /* Return of zlib */
-
-      /* Record the number of bytes available - zlib supports at least 65535
-       * bytes at one step, depending on the size of the zlib type 'uInt', the
-       * maximum size zlib can write at once is ZLIB_IO_MAX (from pngpriv.h).
-       * Use this because on 16 bit systems 'rowbytes' can be up to 65536 (i.e.
-       * one more than 16 bits) and, in this case 'rowbytes+1' can overflow a
-       * uInt.  ZLIB_IO_MAX can be safely reduced to cause zlib to be called
-       * with smaller chunks of data.
-       */
-      if (png_ptr->zstream.avail_in == 0)
-      {
-         if (avail > ZLIB_IO_MAX)
-         {
-            png_ptr->zstream.avail_in  = ZLIB_IO_MAX;
-            avail -= ZLIB_IO_MAX;
-         }
 
-         else
-         {
-            /* So this will fit in the available uInt space: */
-            png_ptr->zstream.avail_in = (uInt)avail;
-            avail = 0;
-         }
-      }
-
-      /* Compress the data */
-      ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);
-
-      /* Check for compression errors */
-      if (ret != Z_OK)
-      {
-         if (png_ptr->zstream.msg != NULL)
-            png_error(png_ptr, png_ptr->zstream.msg);
-
-         else
-            png_error(png_ptr, "zlib error");
-      }
-
-      /* See if it is time to write another IDAT */
-      if (!(png_ptr->zstream.avail_out))
-      {
-         /* Write the IDAT and reset the zlib output buffer */
-         png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
-      }
-   /* Repeat until all data has been compressed */
-   } while (avail > 0 || png_ptr->zstream.avail_in > 0);
+   png_compress_IDAT(png_ptr, filtered_row, full_row_length, Z_NO_FLUSH);
 
+#ifdef PNG_WRITE_FILTER_SUPPORTED
    /* Swap the current and previous rows */
    if (png_ptr->prev_row != NULL)
    {
@@ -3162,6 +3013,7 @@ png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row,
       png_ptr->prev_row = png_ptr->row_buf;
       png_ptr->row_buf = tptr;
    }
+#endif /* WRITE_FILTER */
 
    /* Finish row - updates counters and flushes zlib if last row */
    png_write_finish_row(png_ptr);
@@ -3174,6 +3026,6 @@ png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row,
    {
       png_write_flush(png_ptr);
    }
-#endif
+#endif /* WRITE_FLUSH */
 }
-#endif /* PNG_WRITE_SUPPORTED */
+#endif /* WRITE */
diff --git a/src/3rdparty/libpng/qtpatches.diff b/src/3rdparty/libpng/qtpatches.diff
new file mode 100644
index 0000000..f7e2af5
--- /dev/null
+++ b/src/3rdparty/libpng/qtpatches.diff
@@ -0,0 +1,91 @@
+diff --git a/src/3rdparty/libpng/pngconf.h b/src/3rdparty/libpng/pngconf.h
+index 3f9493e..535c2df 100644
+--- a/src/3rdparty/libpng/pngconf.h
++++ b/src/3rdparty/libpng/pngconf.h
+@@ -196,7 +196,7 @@
+ #    define PNGCAPI __watcall
+ #  endif
+ 
+-#  if defined(__GNUC__) || (defined(_MSC_VER) && (_MSC_VER >= 800))
++#  if defined(__GNUC__) || (defined (_MSC_VER) && (_MSC_VER >= 800)) || defined(__WINSCW__)
+ #    define PNGCAPI __cdecl
+ #    if PNG_API_RULE == 1
+        /* If this line results in an error __stdcall is not understood and
+diff --git a/src/3rdparty/libpng/pnglibconf.h b/src/3rdparty/libpng/pnglibconf.h
+index b4ec3c3..f0fdcf8 100644
+--- a/src/3rdparty/libpng/pnglibconf.h
++++ b/src/3rdparty/libpng/pnglibconf.h
+@@ -27,7 +27,9 @@
+ #define PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
+ #define PNG_COLORSPACE_SUPPORTED
+ #define PNG_CONSOLE_IO_SUPPORTED
++#ifndef _WIN32_WCE
+ #define PNG_CONVERT_tIME_SUPPORTED
++#endif
+ #define PNG_EASY_ACCESS_SUPPORTED
+ /*#undef PNG_ERROR_NUMBERS_SUPPORTED*/
+ #define PNG_ERROR_TEXT_SUPPORTED
+@@ -106,12 +108,14 @@
+ #define PNG_SET_OPTION_SUPPORTED
+ #define PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
+ #define PNG_SET_USER_LIMITS_SUPPORTED
++#ifndef _WIN32_WCE
+ #define PNG_SIMPLIFIED_READ_AFIRST_SUPPORTED
+ #define PNG_SIMPLIFIED_READ_BGR_SUPPORTED
+ #define PNG_SIMPLIFIED_READ_SUPPORTED
+ #define PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
+ #define PNG_SIMPLIFIED_WRITE_BGR_SUPPORTED
+ #define PNG_SIMPLIFIED_WRITE_SUPPORTED
++#endif
+ #define PNG_STDIO_SUPPORTED
+ #define PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
+ #define PNG_TEXT_SUPPORTED
+diff --git a/src/3rdparty/libpng/pngpriv.h b/src/3rdparty/libpng/pngpriv.h
+index 5980a3f..4031d73 100644
+--- a/src/3rdparty/libpng/pngpriv.h
++++ b/src/3rdparty/libpng/pngpriv.h
+@@ -23,6 +23,12 @@
+ #ifndef PNGPRIV_H
+ #define PNGPRIV_H
+ 
++#ifdef _MSC_VER
++#  ifndef _CRT_SECURE_NO_DEPRECATE
++#    define _CRT_SECURE_NO_DEPRECATE
++#  endif
++#endif
++
+ /* Feature Test Macros.  The following are defined here to ensure that correctly
+  * implemented libraries reveal the APIs libpng needs to build and hide those
+  * that are not needed and potentially damaging to the compilation.
+@@ -215,6 +221,11 @@
+ #  endif
+ #endif /* Setting PNG_BUILD_DLL if required */
+ 
++/* Modfied for usage in Qt: Do not export the libpng APIs */
++#ifdef PNG_BUILD_DLL
++#undef PNG_BUILD_DLL
++#endif
++
+ /* See pngconf.h for more details: the builder of the library may set this on
+  * the command line to the right thing for the specific compilation system or it
+  * may be automagically set above (at present we know of no system where it does
+@@ -425,7 +436,9 @@
+ 
+ #if defined(WIN32) || defined(_Windows) || defined(_WINDOWS) || \
+     defined(_WIN32) || defined(__WIN32__)
+-#  include <windows.h>  /* defines _WINDOWS_ macro */
++#  if !defined(__SYMBIAN32__)
++#    include <windows.h>  /* defines _WINDOWS_ macro */
++#  endif
+ #endif
+ #endif /* PNG_VERSION_INFO_ONLY */
+ 
+@@ -436,7 +449,7 @@
+ 
+ /* Memory model/platform independent fns */
+ #ifndef PNG_ABORT
+-#  ifdef _WINDOWS_
++#  if defined(_WINDOWS_) || defined(_WIN32_WCE)
+ #    define PNG_ABORT() ExitProcess(0)
+ #  else
+ #    define PNG_ABORT() abort()