1 files changed, 404 insertions, 291 deletions

diff --git a/src/3rdparty/libpng/pngget.c b/src/3rdparty/libpng/pngget.c
index 8611b85..b5e5798 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 1.4.0 [January 3, 2010]
- * Copyright (c) 1998-2010 Glenn Randers-Pehrson
+ * Last changed in libpng 1.5.1 [February 3, 2011]
+ * Copyright (c) 1998-2011 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.)
  *
@@ -12,47 +12,44 @@
  *
  */
 
-#define PNG_NO_PEDANTIC_WARNINGS
-#include "png.h"
-#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
 #include "pngpriv.h"
 
+#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
+
 png_uint_32 PNGAPI
-png_get_valid(png_structp png_ptr, png_infop info_ptr, png_uint_32 flag)
+png_get_valid(png_const_structp png_ptr, png_const_infop info_ptr,
+    png_uint_32 flag)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return(info_ptr->valid & flag);
 
-   else
-      return(0);
+   return(0);
 }
 
 png_size_t PNGAPI
-png_get_rowbytes(png_structp png_ptr, png_infop info_ptr)
+png_get_rowbytes(png_const_structp png_ptr, png_const_infop info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return(info_ptr->rowbytes);
 
-   else
-      return(0);
+   return(0);
 }
 
 #ifdef PNG_INFO_IMAGE_SUPPORTED
 png_bytepp PNGAPI
-png_get_rows(png_structp png_ptr, png_infop info_ptr)
+png_get_rows(png_const_structp png_ptr, png_const_infop info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return(info_ptr->row_pointers);
 
-   else
-      return(0);
+   return(0);
 }
 #endif
 
 #ifdef PNG_EASY_ACCESS_SUPPORTED
 /* Easy access to info, added in libpng-0.99 */
 png_uint_32 PNGAPI
-png_get_image_width(png_structp png_ptr, png_infop info_ptr)
+png_get_image_width(png_const_structp png_ptr, png_const_infop info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return info_ptr->width;
@@ -61,7 +58,7 @@ png_get_image_width(png_structp png_ptr, png_infop info_ptr)
 }
 
 png_uint_32 PNGAPI
-png_get_image_height(png_structp png_ptr, png_infop info_ptr)
+png_get_image_height(png_const_structp png_ptr, png_const_infop info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return info_ptr->height;
@@ -70,7 +67,7 @@ png_get_image_height(png_structp png_ptr, png_infop info_ptr)
 }
 
 png_byte PNGAPI
-png_get_bit_depth(png_structp png_ptr, png_infop info_ptr)
+png_get_bit_depth(png_const_structp png_ptr, png_const_infop info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return info_ptr->bit_depth;
@@ -79,7 +76,7 @@ png_get_bit_depth(png_structp png_ptr, png_infop info_ptr)
 }
 
 png_byte PNGAPI
-png_get_color_type(png_structp png_ptr, png_infop info_ptr)
+png_get_color_type(png_const_structp png_ptr, png_const_infop info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return info_ptr->color_type;
@@ -88,7 +85,7 @@ png_get_color_type(png_structp png_ptr, png_infop info_ptr)
 }
 
 png_byte PNGAPI
-png_get_filter_type(png_structp png_ptr, png_infop info_ptr)
+png_get_filter_type(png_const_structp png_ptr, png_const_infop info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return info_ptr->filter_type;
@@ -97,7 +94,7 @@ png_get_filter_type(png_structp png_ptr, png_infop info_ptr)
 }
 
 png_byte PNGAPI
-png_get_interlace_type(png_structp png_ptr, png_infop info_ptr)
+png_get_interlace_type(png_const_structp png_ptr, png_const_infop info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return info_ptr->interlace_type;
@@ -106,7 +103,7 @@ png_get_interlace_type(png_structp png_ptr, png_infop info_ptr)
 }
 
 png_byte PNGAPI
-png_get_compression_type(png_structp png_ptr, png_infop info_ptr)
+png_get_compression_type(png_const_structp png_ptr, png_const_infop info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return info_ptr->compression_type;
@@ -115,222 +112,275 @@ png_get_compression_type(png_structp png_ptr, png_infop info_ptr)
 }
 
 png_uint_32 PNGAPI
-png_get_x_pixels_per_meter(png_structp png_ptr, png_infop info_ptr)
+png_get_x_pixels_per_meter(png_const_structp png_ptr, png_const_infop info_ptr)
 {
-   if (png_ptr != NULL && info_ptr != NULL)
 #ifdef PNG_pHYs_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_pHYs)
-   {
-      png_debug1(1, "in %s retrieval function", "png_get_x_pixels_per_meter");
-
-      if (info_ptr->phys_unit_type != PNG_RESOLUTION_METER)
-          return (0);
+   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
+      {
+         png_debug1(1, "in %s retrieval function",
+             "png_get_x_pixels_per_meter");
 
-      else
-          return (info_ptr->x_pixels_per_unit);
-   }
-#else
-   return (0);
+         if (info_ptr->phys_unit_type == PNG_RESOLUTION_METER)
+            return (info_ptr->x_pixels_per_unit);
+      }
 #endif
+
    return (0);
 }
 
 png_uint_32 PNGAPI
-png_get_y_pixels_per_meter(png_structp png_ptr, png_infop info_ptr)
+png_get_y_pixels_per_meter(png_const_structp png_ptr, png_const_infop info_ptr)
 {
-   if (png_ptr != NULL && info_ptr != NULL)
 #ifdef PNG_pHYs_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_pHYs)
+   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
    {
-      png_debug1(1, "in %s retrieval function", "png_get_y_pixels_per_meter");
-
-      if (info_ptr->phys_unit_type != PNG_RESOLUTION_METER)
-          return (0);
+      png_debug1(1, "in %s retrieval function",
+          "png_get_y_pixels_per_meter");
 
-      else
-          return (info_ptr->y_pixels_per_unit);
+      if (info_ptr->phys_unit_type == PNG_RESOLUTION_METER)
+         return (info_ptr->y_pixels_per_unit);
    }
-#else
-   return (0);
 #endif
+
    return (0);
 }
 
 png_uint_32 PNGAPI
-png_get_pixels_per_meter(png_structp png_ptr, png_infop info_ptr)
+png_get_pixels_per_meter(png_const_structp png_ptr, png_const_infop info_ptr)
 {
-   if (png_ptr != NULL && info_ptr != NULL)
 #ifdef PNG_pHYs_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_pHYs)
+   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
    {
       png_debug1(1, "in %s retrieval function", "png_get_pixels_per_meter");
 
-      if (info_ptr->phys_unit_type != PNG_RESOLUTION_METER ||
-         info_ptr->x_pixels_per_unit != info_ptr->y_pixels_per_unit)
-          return (0);
-
-      else
-          return (info_ptr->x_pixels_per_unit);
+      if (info_ptr->phys_unit_type == PNG_RESOLUTION_METER &&
+          info_ptr->x_pixels_per_unit == info_ptr->y_pixels_per_unit)
+         return (info_ptr->x_pixels_per_unit);
    }
-#else
-   return (0);
 #endif
+
    return (0);
 }
 
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 float PNGAPI
-png_get_pixel_aspect_ratio(png_structp png_ptr, png_infop info_ptr)
-   {
-   if (png_ptr != NULL && info_ptr != NULL)
-#ifdef PNG_pHYs_SUPPORTED
-
-   if (info_ptr->valid & PNG_INFO_pHYs)
+png_get_pixel_aspect_ratio(png_const_structp png_ptr, png_const_infop info_ptr)
+{
+#ifdef PNG_READ_pHYs_SUPPORTED
+   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
    {
       png_debug1(1, "in %s retrieval function", "png_get_aspect_ratio");
 
-      if (info_ptr->x_pixels_per_unit == 0)
-         return ((float)0.0);
-
-      else
+      if (info_ptr->x_pixels_per_unit != 0)
          return ((float)((float)info_ptr->y_pixels_per_unit
-            /(float)info_ptr->x_pixels_per_unit));
+             /(float)info_ptr->x_pixels_per_unit));
    }
-#else
-      return (0.0);
 #endif
+
    return ((float)0.0);
 }
 #endif
 
+#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)
+{
+#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)
+   {
+      png_fixed_point res;
+
+      png_debug1(1, "in %s retrieval function", "png_get_aspect_ratio_fixed");
+
+      /* The following casts work because a PNG 4 byte integer only has a valid
+       * 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))
+         return res;
+   }
+#endif
+
+   return 0;
+}
+#endif
+
 png_int_32 PNGAPI
-png_get_x_offset_microns(png_structp png_ptr, png_infop info_ptr)
+png_get_x_offset_microns(png_const_structp png_ptr, png_const_infop info_ptr)
 {
-   if (png_ptr != NULL && info_ptr != NULL)
 #ifdef PNG_oFFs_SUPPORTED
-
-   if (info_ptr->valid & PNG_INFO_oFFs)
+   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
    {
       png_debug1(1, "in %s retrieval function", "png_get_x_offset_microns");
 
-      if (info_ptr->offset_unit_type != PNG_OFFSET_MICROMETER)
-          return (0);
-
-      else
-          return (info_ptr->x_offset);
+      if (info_ptr->offset_unit_type == PNG_OFFSET_MICROMETER)
+         return (info_ptr->x_offset);
    }
-#else
-      return (0);
 #endif
+
    return (0);
 }
 
 png_int_32 PNGAPI
-png_get_y_offset_microns(png_structp png_ptr, png_infop info_ptr)
+png_get_y_offset_microns(png_const_structp png_ptr, png_const_infop info_ptr)
 {
-   if (png_ptr != NULL && info_ptr != NULL)
-
 #ifdef PNG_oFFs_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_oFFs)
+   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
    {
       png_debug1(1, "in %s retrieval function", "png_get_y_offset_microns");
 
-      if (info_ptr->offset_unit_type != PNG_OFFSET_MICROMETER)
-          return (0);
-
-      else
-          return (info_ptr->y_offset);
+      if (info_ptr->offset_unit_type == PNG_OFFSET_MICROMETER)
+         return (info_ptr->y_offset);
    }
-#else
-   return (0);
 #endif
+
    return (0);
 }
 
 png_int_32 PNGAPI
-png_get_x_offset_pixels(png_structp png_ptr, png_infop info_ptr)
+png_get_x_offset_pixels(png_const_structp png_ptr, png_const_infop info_ptr)
 {
-   if (png_ptr != NULL && info_ptr != NULL)
-
 #ifdef PNG_oFFs_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_oFFs)
+   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
    {
-      png_debug1(1, "in %s retrieval function", "png_get_x_offset_microns");
-
-      if (info_ptr->offset_unit_type != PNG_OFFSET_PIXEL)
-          return (0);
+      png_debug1(1, "in %s retrieval function", "png_get_x_offset_pixels");
 
-      else
-          return (info_ptr->x_offset);
+      if (info_ptr->offset_unit_type == PNG_OFFSET_PIXEL)
+         return (info_ptr->x_offset);
    }
-#else
-   return (0);
 #endif
+
    return (0);
 }
 
 png_int_32 PNGAPI
-png_get_y_offset_pixels(png_structp png_ptr, png_infop info_ptr)
+png_get_y_offset_pixels(png_const_structp png_ptr, png_const_infop info_ptr)
 {
-   if (png_ptr != NULL && info_ptr != NULL)
-
 #ifdef PNG_oFFs_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_oFFs)
+   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
    {
-      png_debug1(1, "in %s retrieval function", "png_get_y_offset_microns");
+      png_debug1(1, "in %s retrieval function", "png_get_y_offset_pixels");
 
-      if (info_ptr->offset_unit_type != PNG_OFFSET_PIXEL)
-          return (0);
-
-      else
-          return (info_ptr->y_offset);
+      if (info_ptr->offset_unit_type == PNG_OFFSET_PIXEL)
+         return (info_ptr->y_offset);
    }
-#else
-   return (0);
 #endif
+
    return (0);
 }
 
-#if defined(PNG_INCH_CONVERSIONS) && defined(PNG_FLOATING_POINT_SUPPORTED)
+#ifdef PNG_INCH_CONVERSIONS_SUPPORTED
+static png_uint_32
+ppi_from_ppm(png_uint_32 ppm)
+{
+#if 0
+   /* The conversion is *(2.54/100), in binary (32 digits):
+    * .00000110100000001001110101001001
+    */
+   png_uint_32 t1001, t1101;
+   ppm >>= 1;                  /* .1 */
+   t1001 = ppm + (ppm >> 3);   /* .1001 */
+   t1101 = t1001 + (ppm >> 1); /* .1101 */
+   ppm >>= 20;                 /* .000000000000000000001 */
+   t1101 += t1101 >> 15;       /* .1101000000000001101 */
+   t1001 >>= 11;               /* .000000000001001 */
+   t1001 += t1001 >> 12;       /* .000000000001001000000001001 */
+   ppm += t1001;               /* .000000000001001000001001001 */
+   ppm += t1101;               /* .110100000001001110101001001 */
+   return (ppm + 16) >> 5;/* .00000110100000001001110101001001 */
+#else
+   /* The argument is a PNG unsigned integer, so it is not permitted
+    * to be bigger than 2^31.
+    */
+   png_fixed_point result;
+   if (ppm <= PNG_UINT_31_MAX && png_muldiv(&result, (png_int_32)ppm, 127,
+       5000))
+      return result;
+
+   /* Overflow. */
+   return 0;
+#endif
+}
+
 png_uint_32 PNGAPI
-png_get_pixels_per_inch(png_structp png_ptr, png_infop info_ptr)
+png_get_pixels_per_inch(png_const_structp png_ptr, png_const_infop info_ptr)
 {
-   return ((png_uint_32)((float)png_get_pixels_per_meter(png_ptr, info_ptr)
-     *.0254 +.5));
+   return ppi_from_ppm(png_get_pixels_per_meter(png_ptr, info_ptr));
 }
 
 png_uint_32 PNGAPI
-png_get_x_pixels_per_inch(png_structp png_ptr, png_infop info_ptr)
+png_get_x_pixels_per_inch(png_const_structp png_ptr, png_const_infop info_ptr)
 {
-   return ((png_uint_32)((float)png_get_x_pixels_per_meter(png_ptr, info_ptr)
-     *.0254 +.5));
+   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_structp png_ptr, png_infop info_ptr)
+png_get_y_pixels_per_inch(png_const_structp png_ptr, png_const_infop 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)
+{
+   /* 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.
+    * Notice that this can overflow - a warning is output and 0 is
+    * returned.
+    */
+   return png_muldiv_warn(png_ptr, microns, 500, 127);
+}
+
+png_fixed_point PNGAPI
+png_get_x_offset_inches_fixed(png_structp png_ptr,
+    png_const_infop info_ptr)
+{
+   return png_fixed_inches_from_microns(png_ptr,
+       png_get_x_offset_microns(png_ptr, info_ptr));
+}
+#endif
+
+#ifdef PNG_FIXED_POINT_SUPPORTED
+png_fixed_point PNGAPI
+png_get_y_offset_inches_fixed(png_structp png_ptr,
+    png_const_infop info_ptr)
 {
-   return ((png_uint_32)((float)png_get_y_pixels_per_meter(png_ptr, info_ptr)
-     *.0254 +.5));
+   return png_fixed_inches_from_microns(png_ptr,
+       png_get_y_offset_microns(png_ptr, info_ptr));
 }
+#endif
 
+#ifdef PNG_FLOATING_POINT_SUPPORTED
 float PNGAPI
-png_get_x_offset_inches(png_structp png_ptr, png_infop info_ptr)
+png_get_x_offset_inches(png_const_structp png_ptr, png_const_infop info_ptr)
 {
-   return ((float)png_get_x_offset_microns(png_ptr, info_ptr)
-     *.00003937);
+   /* To avoid the overflow do the conversion directly in floating
+    * point.
+    */
+   return (float)(png_get_x_offset_microns(png_ptr, info_ptr) * .00003937);
 }
+#endif
 
+#ifdef PNG_FLOATING_POINT_SUPPORTED
 float PNGAPI
-png_get_y_offset_inches(png_structp png_ptr, png_infop info_ptr)
+png_get_y_offset_inches(png_const_structp png_ptr, png_const_infop info_ptr)
 {
-   return ((float)png_get_y_offset_microns(png_ptr, info_ptr)
-     *.00003937);
+   /* To avoid the overflow do the conversion directly in floating
+    * point.
+    */
+   return (float)(png_get_y_offset_microns(png_ptr, info_ptr) * .00003937);
 }
+#endif
 
 #ifdef PNG_pHYs_SUPPORTED
 png_uint_32 PNGAPI
-png_get_pHYs_dpi(png_structp png_ptr, png_infop info_ptr,
-   png_uint_32 *res_x, png_uint_32 *res_y, int *unit_type)
+png_get_pHYs_dpi(png_const_structp png_ptr, png_const_infop info_ptr,
+    png_uint_32 *res_x, png_uint_32 *res_y, int *unit_type)
 {
    png_uint_32 retval = 0;
 
@@ -343,15 +393,18 @@ png_get_pHYs_dpi(png_structp png_ptr, png_infop info_ptr,
          *res_x = info_ptr->x_pixels_per_unit;
          retval |= PNG_INFO_pHYs;
       }
+
       if (res_y != NULL)
       {
          *res_y = info_ptr->y_pixels_per_unit;
          retval |= PNG_INFO_pHYs;
       }
+
       if (unit_type != NULL)
       {
          *unit_type = (int)info_ptr->phys_unit_type;
          retval |= PNG_INFO_pHYs;
+
          if (*unit_type == 1)
          {
             if (res_x != NULL) *res_x = (png_uint_32)(*res_x * .0254 + .50);
@@ -359,176 +412,182 @@ png_get_pHYs_dpi(png_structp png_ptr, png_infop info_ptr,
          }
       }
    }
+
    return (retval);
 }
 #endif /* PNG_pHYs_SUPPORTED */
-#endif  /* PNG_INCH_CONVERSIONS && PNG_FLOATING_POINT_SUPPORTED */
+#endif  /* PNG_INCH_CONVERSIONS_SUPPORTED */
 
 /* png_get_channels really belongs in here, too, but it's been around longer */
 
 #endif  /* PNG_EASY_ACCESS_SUPPORTED */
 
 png_byte PNGAPI
-png_get_channels(png_structp png_ptr, png_infop info_ptr)
+png_get_channels(png_const_structp png_ptr, png_const_infop info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return(info_ptr->channels);
-   else
-      return (0);
+
+   return (0);
 }
 
-png_bytep PNGAPI
-png_get_signature(png_structp png_ptr, png_infop info_ptr)
+png_const_bytep PNGAPI
+png_get_signature(png_const_structp png_ptr, png_infop info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
       return(info_ptr->signature);
-   else
-      return (NULL);
+
+   return (NULL);
 }
 
 #ifdef PNG_bKGD_SUPPORTED
 png_uint_32 PNGAPI
-png_get_bKGD(png_structp png_ptr, png_infop info_ptr,
+png_get_bKGD(png_const_structp png_ptr, png_infop info_ptr,
    png_color_16p *background)
 {
    if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD)
-      && background != NULL)
+       && background != NULL)
    {
       png_debug1(1, "in %s retrieval function", "bKGD");
 
       *background = &(info_ptr->background);
       return (PNG_INFO_bKGD);
    }
+
    return (0);
 }
 #endif
 
 #ifdef PNG_cHRM_SUPPORTED
-#ifdef PNG_FLOATING_POINT_SUPPORTED
+#  ifdef PNG_FLOATING_POINT_SUPPORTED
 png_uint_32 PNGAPI
-png_get_cHRM(png_structp png_ptr, png_infop 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_get_cHRM(png_const_structp png_ptr, png_const_infop 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))
    {
       png_debug1(1, "in %s retrieval function", "cHRM");
 
       if (white_x != NULL)
-         *white_x = (double)info_ptr->x_white;
+         *white_x = png_float(png_ptr, info_ptr->x_white, "cHRM white X");
       if (white_y != NULL)
-         *white_y = (double)info_ptr->y_white;
+         *white_y = png_float(png_ptr, info_ptr->y_white, "cHRM white Y");
       if (red_x != NULL)
-         *red_x = (double)info_ptr->x_red;
+         *red_x = png_float(png_ptr, info_ptr->x_red, "cHRM red X");
       if (red_y != NULL)
-         *red_y = (double)info_ptr->y_red;
+         *red_y = png_float(png_ptr, info_ptr->y_red, "cHRM red Y");
       if (green_x != NULL)
-         *green_x = (double)info_ptr->x_green;
+         *green_x = png_float(png_ptr, info_ptr->x_green, "cHRM green X");
       if (green_y != NULL)
-         *green_y = (double)info_ptr->y_green;
+         *green_y = png_float(png_ptr, info_ptr->y_green, "cHRM green Y");
       if (blue_x != NULL)
-         *blue_x = (double)info_ptr->x_blue;
+         *blue_x = png_float(png_ptr, info_ptr->x_blue, "cHRM blue X");
       if (blue_y != NULL)
-         *blue_y = (double)info_ptr->y_blue;
+         *blue_y = png_float(png_ptr, info_ptr->y_blue, "cHRM blue Y");
       return (PNG_INFO_cHRM);
    }
+
    return (0);
 }
-#endif
-#ifdef PNG_FIXED_POINT_SUPPORTED
+#  endif
+
+#  ifdef PNG_FIXED_POINT_SUPPORTED
 png_uint_32 PNGAPI
-png_get_cHRM_fixed(png_structp png_ptr, png_infop 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_get_cHRM_fixed(png_const_structp png_ptr, png_const_infop 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 (white_x != NULL)
-         *white_x = info_ptr->int_x_white;
+         *white_x = info_ptr->x_white;
       if (white_y != NULL)
-         *white_y = info_ptr->int_y_white;
+         *white_y = info_ptr->y_white;
       if (red_x != NULL)
-         *red_x = info_ptr->int_x_red;
+         *red_x = info_ptr->x_red;
       if (red_y != NULL)
-         *red_y = info_ptr->int_y_red;
+         *red_y = info_ptr->y_red;
       if (green_x != NULL)
-         *green_x = info_ptr->int_x_green;
+         *green_x = info_ptr->x_green;
       if (green_y != NULL)
-         *green_y = info_ptr->int_y_green;
+         *green_y = info_ptr->y_green;
       if (blue_x != NULL)
-         *blue_x = info_ptr->int_x_blue;
+         *blue_x = info_ptr->x_blue;
       if (blue_y != NULL)
-         *blue_y = info_ptr->int_y_blue;
+         *blue_y = info_ptr->y_blue;
       return (PNG_INFO_cHRM);
    }
+
    return (0);
 }
-#endif
+#  endif
 #endif
 
 #ifdef PNG_gAMA_SUPPORTED
-#ifdef PNG_FLOATING_POINT_SUPPORTED
-png_uint_32 PNGAPI
-png_get_gAMA(png_structp png_ptr, png_infop info_ptr, double *file_gamma)
+png_uint_32 PNGFAPI
+png_get_gAMA_fixed(png_const_structp png_ptr, png_const_infop 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)
+       && file_gamma != NULL)
    {
-      *file_gamma = (double)info_ptr->gamma;
+      *file_gamma = info_ptr->gamma;
       return (PNG_INFO_gAMA);
    }
+
    return (0);
 }
-#endif
-#ifdef PNG_FIXED_POINT_SUPPORTED
+#  ifdef PNG_FLOATING_POINT_SUPPORTED
 png_uint_32 PNGAPI
-png_get_gAMA_fixed(png_structp png_ptr, png_infop info_ptr,
-    png_fixed_point *int_file_gamma)
+png_get_gAMA(png_const_structp png_ptr, png_const_infop info_ptr,
+    double *file_gamma)
 {
-   png_debug1(1, "in %s retrieval function", "gAMA");
+   png_fixed_point igamma;
+   png_uint_32 ok = png_get_gAMA_fixed(png_ptr, info_ptr, &igamma);
 
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_gAMA)
-      && int_file_gamma != NULL)
-   {
-      *int_file_gamma = info_ptr->int_gamma;
-      return (PNG_INFO_gAMA);
-   }
-   return (0);
+   if (ok)
+      *file_gamma = png_float(png_ptr, igamma, "png_get_gAMA");
+
+   return ok;
 }
-#endif
+
+#  endif
 #endif
 
 #ifdef PNG_sRGB_SUPPORTED
 png_uint_32 PNGAPI
-png_get_sRGB(png_structp png_ptr, png_infop info_ptr, int *file_srgb_intent)
+png_get_sRGB(png_const_structp png_ptr, png_const_infop 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)
+       && file_srgb_intent != NULL)
    {
       *file_srgb_intent = (int)info_ptr->srgb_intent;
       return (PNG_INFO_sRGB);
    }
+
    return (0);
 }
 #endif
 
 #ifdef PNG_iCCP_SUPPORTED
 png_uint_32 PNGAPI
-png_get_iCCP(png_structp png_ptr, png_infop info_ptr,
-             png_charpp name, int *compression_type,
-             png_charpp profile, png_uint_32 *proflen)
+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_debug1(1, "in %s retrieval function", "iCCP");
 
    if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_iCCP)
-      && name != NULL && profile != NULL && proflen != NULL)
+       && name != NULL && profile != NULL && proflen != NULL)
    {
       *name = info_ptr->iccp_name;
       *profile = info_ptr->iccp_profile;
@@ -539,45 +598,49 @@ png_get_iCCP(png_structp png_ptr, png_infop info_ptr,
       *compression_type = (int)info_ptr->iccp_compression;
       return (PNG_INFO_iCCP);
    }
+
    return (0);
 }
 #endif
 
 #ifdef PNG_sPLT_SUPPORTED
 png_uint_32 PNGAPI
-png_get_sPLT(png_structp png_ptr, png_infop info_ptr,
-             png_sPLT_tpp spalettes)
+png_get_sPLT(png_const_structp png_ptr, png_const_infop 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);
+      *spalettes = info_ptr->splt_palettes;
+      return ((png_uint_32)info_ptr->splt_palettes_num);
    }
+
    return (0);
 }
 #endif
 
 #ifdef PNG_hIST_SUPPORTED
 png_uint_32 PNGAPI
-png_get_hIST(png_structp png_ptr, png_infop info_ptr, png_uint_16p *hist)
+png_get_hIST(png_const_structp png_ptr, png_const_infop 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)
+       && hist != NULL)
    {
       *hist = info_ptr->hist;
       return (PNG_INFO_hIST);
    }
+
    return (0);
 }
 #endif
 
 png_uint_32 PNGAPI
 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_type, int *compression_type,
-   int *filter_type)
+    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");
@@ -614,28 +677,29 @@ png_get_IHDR(png_structp png_ptr, png_infop info_ptr,
 
 #ifdef PNG_oFFs_SUPPORTED
 png_uint_32 PNGAPI
-png_get_oFFs(png_structp png_ptr, png_infop info_ptr,
-   png_int_32 *offset_x, png_int_32 *offset_y, int *unit_type)
+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_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)
+       && offset_x != NULL && offset_y != NULL && unit_type != NULL)
    {
       *offset_x = info_ptr->x_offset;
       *offset_y = info_ptr->y_offset;
       *unit_type = (int)info_ptr->offset_unit_type;
       return (PNG_INFO_oFFs);
    }
+
    return (0);
 }
 #endif
 
 #ifdef PNG_pCAL_SUPPORTED
 png_uint_32 PNGAPI
-png_get_pCAL(png_structp png_ptr, png_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_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_debug1(1, "in %s retrieval function", "pCAL");
 
@@ -652,57 +716,78 @@ png_get_pCAL(png_structp png_ptr, png_infop info_ptr,
       *params = info_ptr->pcal_params;
       return (PNG_INFO_pCAL);
    }
+
    return (0);
 }
 #endif
 
 #ifdef PNG_sCAL_SUPPORTED
-#ifdef PNG_FLOATING_POINT_SUPPORTED
+#  ifdef PNG_FIXED_POINT_SUPPORTED
+#    ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
+png_uint_32 PNGAPI
+png_get_sCAL_fixed(png_structp png_ptr, png_const_infop 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))
+   {
+      *unit = info_ptr->scal_unit;
+      /*TODO: make this work without FP support */
+      *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");
+      return (PNG_INFO_sCAL);
+   }
+
+   return(0);
+}
+#    endif /* FLOATING_ARITHMETIC */
+#  endif /* FIXED_POINT */
+#  ifdef PNG_FLOATING_POINT_SUPPORTED
 png_uint_32 PNGAPI
-png_get_sCAL(png_structp png_ptr, png_infop info_ptr,
-             int *unit, double *width, double *height)
+png_get_sCAL(png_const_structp png_ptr, png_const_infop info_ptr,
+    int *unit, double *width, double *height)
 {
-    if (png_ptr != NULL && info_ptr != NULL &&
-        (info_ptr->valid & PNG_INFO_sCAL))
-    {
-        *unit = info_ptr->scal_unit;
-        *width = info_ptr->scal_pixel_width;
-        *height = info_ptr->scal_pixel_height;
-        return (PNG_INFO_sCAL);
-    }
-    return(0);
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_sCAL))
+   {
+      *unit = info_ptr->scal_unit;
+      *width = atof(info_ptr->scal_s_width);
+      *height = atof(info_ptr->scal_s_height);
+      return (PNG_INFO_sCAL);
+   }
+
+   return(0);
 }
-#else
-#ifdef PNG_FIXED_POINT_SUPPORTED
+#  endif /* FLOATING POINT */
 png_uint_32 PNGAPI
-png_get_sCAL_s(png_structp png_ptr, png_infop info_ptr,
-             int *unit, png_charpp width, png_charpp height)
+png_get_sCAL_s(png_const_structp png_ptr, png_const_infop info_ptr,
+    int *unit, png_charpp width, png_charpp height)
 {
-    if (png_ptr != NULL && info_ptr != NULL &&
-        (info_ptr->valid & PNG_INFO_sCAL))
-    {
-        *unit = info_ptr->scal_unit;
-        *width = info_ptr->scal_s_width;
-        *height = info_ptr->scal_s_height;
-        return (PNG_INFO_sCAL);
-    }
-    return(0);
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_sCAL))
+   {
+      *unit = info_ptr->scal_unit;
+      *width = info_ptr->scal_s_width;
+      *height = info_ptr->scal_s_height;
+      return (PNG_INFO_sCAL);
+   }
+
+   return(0);
 }
-#endif
-#endif
-#endif
+#endif /* sCAL */
 
 #ifdef PNG_pHYs_SUPPORTED
 png_uint_32 PNGAPI
-png_get_pHYs(png_structp png_ptr, png_infop info_ptr,
-   png_uint_32 *res_x, png_uint_32 *res_y, int *unit_type)
+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_uint_32 retval = 0;
 
    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))
    {
       if (res_x != NULL)
       {
@@ -722,13 +807,14 @@ png_get_pHYs(png_structp png_ptr, png_infop info_ptr,
          retval |= PNG_INFO_pHYs;
       }
    }
+
    return (retval);
 }
-#endif
+#endif /* pHYs */
 
 png_uint_32 PNGAPI
-png_get_PLTE(png_structp png_ptr, png_infop info_ptr, png_colorp *palette,
-   int *num_palette)
+png_get_PLTE(png_const_structp png_ptr, png_const_infop info_ptr,
+    png_colorp *palette, int *num_palette)
 {
    png_debug1(1, "in %s retrieval function", "PLTE");
 
@@ -740,35 +826,38 @@ png_get_PLTE(png_structp png_ptr, png_infop info_ptr, png_colorp *palette,
       png_debug1(3, "num_palette = %d", *num_palette);
       return (PNG_INFO_PLTE);
    }
+
    return (0);
 }
 
 #ifdef PNG_sBIT_SUPPORTED
 png_uint_32 PNGAPI
-png_get_sBIT(png_structp png_ptr, png_infop info_ptr, png_color_8p *sig_bit)
+png_get_sBIT(png_const_structp png_ptr, png_infop 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)
+       && sig_bit != NULL)
    {
       *sig_bit = &(info_ptr->sig_bit);
       return (PNG_INFO_sBIT);
    }
+
    return (0);
 }
 #endif
 
 #ifdef PNG_TEXT_SUPPORTED
 png_uint_32 PNGAPI
-png_get_text(png_structp png_ptr, png_infop info_ptr, png_textp *text_ptr,
-   int *num_text)
+png_get_text(png_const_structp png_ptr, png_const_infop info_ptr,
+    png_textp *text_ptr, int *num_text)
 {
    if (png_ptr != NULL && info_ptr != NULL && info_ptr->num_text > 0)
    {
       png_debug1(1, "in %s retrieval function",
-         (png_ptr->chunk_name[0] == '\0' ? "text"
-             : (png_const_charp)png_ptr->chunk_name));
+          (png_ptr->chunk_name[0] == '\0' ? "text" :
+          (png_const_charp)png_ptr->chunk_name));
 
       if (text_ptr != NULL)
          *text_ptr = info_ptr->text;
@@ -778,15 +867,17 @@ png_get_text(png_structp png_ptr, png_infop info_ptr, png_textp *text_ptr,
 
       return ((png_uint_32)info_ptr->num_text);
    }
+
    if (num_text != NULL)
-     *num_text = 0;
+      *num_text = 0;
+
    return(0);
 }
 #endif
 
 #ifdef PNG_tIME_SUPPORTED
 png_uint_32 PNGAPI
-png_get_tIME(png_structp png_ptr, png_infop info_ptr, png_timep *mod_time)
+png_get_tIME(png_const_structp png_ptr, png_infop info_ptr, png_timep *mod_time)
 {
    png_debug1(1, "in %s retrieval function", "tIME");
 
@@ -796,14 +887,15 @@ png_get_tIME(png_structp png_ptr, png_infop info_ptr, png_timep *mod_time)
       *mod_time = &(info_ptr->mod_time);
       return (PNG_INFO_tIME);
    }
+
    return (0);
 }
 #endif
 
 #ifdef PNG_tRNS_SUPPORTED
 png_uint_32 PNGAPI
-png_get_tRNS(png_structp png_ptr, png_infop info_ptr,
-   png_bytep *trans_alpha, int *num_trans, png_color_16p *trans_color)
+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_uint_32 retval = 0;
    if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
@@ -812,104 +904,125 @@ png_get_tRNS(png_structp png_ptr, png_infop info_ptr,
 
       if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
       {
-          if (trans_alpha != NULL)
-          {
-             *trans_alpha = info_ptr->trans_alpha;
-             retval |= PNG_INFO_tRNS;
-          }
-
-          if (trans_color != NULL)
-             *trans_color = &(info_ptr->trans_color);
+         if (trans_alpha != NULL)
+         {
+            *trans_alpha = info_ptr->trans_alpha;
+            retval |= PNG_INFO_tRNS;
+         }
+
+         if (trans_color != NULL)
+            *trans_color = &(info_ptr->trans_color);
       }
+
       else /* if (info_ptr->color_type != PNG_COLOR_TYPE_PALETTE) */
       {
-          if (trans_color != NULL)
-          {
-             *trans_color = &(info_ptr->trans_color);
-             retval |= PNG_INFO_tRNS;
-          }
-
-          if (trans_alpha != NULL)
-             *trans_alpha = NULL;
+         if (trans_color != NULL)
+         {
+            *trans_color = &(info_ptr->trans_color);
+            retval |= PNG_INFO_tRNS;
+         }
+
+         if (trans_alpha != NULL)
+            *trans_alpha = NULL;
       }
+
       if (num_trans != NULL)
       {
          *num_trans = info_ptr->num_trans;
          retval |= PNG_INFO_tRNS;
       }
    }
+
    return (retval);
 }
 #endif
 
 #ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
-png_uint_32 PNGAPI
-png_get_unknown_chunks(png_structp png_ptr, png_infop info_ptr,
-             png_unknown_chunkpp unknowns)
+int PNGAPI
+png_get_unknown_chunks(png_const_structp png_ptr, png_const_infop info_ptr,
+    png_unknown_chunkpp unknowns)
 {
    if (png_ptr != NULL && info_ptr != NULL && unknowns != NULL)
    {
-     *unknowns = info_ptr->unknown_chunks;
-     return ((png_uint_32)info_ptr->unknown_chunks_num);
+      *unknowns = info_ptr->unknown_chunks;
+      return info_ptr->unknown_chunks_num;
    }
+
    return (0);
 }
 #endif
 
 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
 png_byte PNGAPI
-png_get_rgb_to_gray_status (png_structp png_ptr)
+png_get_rgb_to_gray_status (png_const_structp png_ptr)
 {
-   return (png_byte)(png_ptr? png_ptr->rgb_to_gray_status : 0);
+   return (png_byte)(png_ptr ? png_ptr->rgb_to_gray_status : 0);
 }
 #endif
 
 #ifdef PNG_USER_CHUNKS_SUPPORTED
 png_voidp PNGAPI
-png_get_user_chunk_ptr(png_structp png_ptr)
+png_get_user_chunk_ptr(png_const_structp png_ptr)
 {
-   return (png_ptr? png_ptr->user_chunk_ptr : NULL);
+   return (png_ptr ? png_ptr->user_chunk_ptr : NULL);
 }
 #endif
 
-#ifdef PNG_WRITE_SUPPORTED
 png_size_t PNGAPI
-png_get_compression_buffer_size(png_structp png_ptr)
+png_get_compression_buffer_size(png_const_structp png_ptr)
 {
    return (png_ptr ? png_ptr->zbuf_size : 0L);
 }
-#endif
 
 
 #ifdef PNG_SET_USER_LIMITS_SUPPORTED
-/* These functions were added to libpng 1.2.6 */
+/* 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_structp png_ptr)
+png_get_user_width_max (png_const_structp png_ptr)
 {
-    return (png_ptr? png_ptr->user_width_max : 0);
+   return (png_ptr ? png_ptr->user_width_max : 0);
 }
+
 png_uint_32 PNGAPI
-png_get_user_height_max (png_structp png_ptr)
+png_get_user_height_max (png_const_structp png_ptr)
 {
-    return (png_ptr? png_ptr->user_height_max : 0);
+   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_structp png_ptr)
+png_get_chunk_cache_max (png_const_structp 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)
 {
-    return (png_ptr? png_ptr->user_chunk_cache_max? 0x7fffffffL :
-       png_ptr->user_chunk_cache_max - 1 : 0);
+   return (png_ptr ? png_ptr->user_chunk_malloc_max : 0);
 }
 #endif /* ?PNG_SET_USER_LIMITS_SUPPORTED */
 
+/* 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)
 {
-    return png_ptr->io_state;
+   return png_ptr->io_state;
+}
+
+png_uint_32 PNGAPI
+png_get_io_chunk_type (png_const_structp png_ptr)
+{
+   return ((png_ptr->chunk_name[0] << 24) +
+           (png_ptr->chunk_name[1] << 16) +
+           (png_ptr->chunk_name[2] <<  8) +
+           (png_ptr->chunk_name[3]));
 }
 
-png_bytep PNGAPI
+png_const_bytep PNGAPI
 png_get_io_chunk_name (png_structp png_ptr)
 {
    return png_ptr->chunk_name;