diff options
Diffstat (limited to 'generic/tkImgPNG.c')
| -rw-r--r-- | generic/tkImgPNG.c | 93 |
1 files changed, 90 insertions, 3 deletions
diff --git a/generic/tkImgPNG.c b/generic/tkImgPNG.c index 0468ca9..c138b78 100644 --- a/generic/tkImgPNG.c +++ b/generic/tkImgPNG.c @@ -9,7 +9,7 @@ * See the file "license.terms" for information on usage and redistribution of * this file, and for a DISCLAIMER OF ALL WARRANTIES. * - * RCS: @(#) $Id: tkImgPNG.c,v 1.5 2010/02/05 22:45:03 nijtmans Exp $ + * RCS: @(#) $Id: tkImgPNG.c,v 1.6 2010/04/12 08:40:15 dkf Exp $ */ #include "tkInt.h" @@ -256,6 +256,8 @@ static inline int WriteChunk(Tcl_Interp *interp, PNGImage *pngPtr, static int WriteData(Tcl_Interp *interp, PNGImage *pngPtr, const unsigned char *srcPtr, int srcSz, unsigned long *crcPtr); +static int WriteExtraChunks(Tcl_Interp *interp, + PNGImage *pngPtr); static int WriteIHDR(Tcl_Interp *interp, PNGImage *pngPtr, Tk_PhotoImageBlock *blockPtr); static int WriteIDAT(Tcl_Interp *interp, PNGImage *pngPtr, @@ -2127,6 +2129,22 @@ ReadIDAT( */ } + /* + * Ensure that when we've got to the end of the compressed data, we've + * also got to the end of the compressed stream. This sanity check is + * enforced by most PNG readers. + */ + + if (!Tcl_ZlibStreamEof(pngPtr->stream)) { + Tcl_AppendResult(interp, "unfinalized data stream in PNG data", NULL); + return TCL_ERROR; + } + if (chunkSz != 0) { + Tcl_AppendResult(interp, + "compressed data after stream finalize in PNG data", NULL); + return TCL_ERROR; + } + if (CheckCRC(interp, pngPtr, crc) == TCL_ERROR) { return TCL_ERROR; } @@ -3099,11 +3117,13 @@ WriteIDAT( /* * Compress the line of pixels into the destination. If this is the - * last line, flush at the same time. + * last line, finalize the compressor at the same time. Note that this + * can't be just a flush; that leads to a file that some PNG readers + * choke on. [Bug 2984787] */ if (rowNum + 1 == blockPtr->height) { - flush = TCL_ZLIB_FLUSH; + flush = TCL_ZLIB_FINALIZE; } if (Tcl_ZlibStreamPut(pngPtr->stream, pngPtr->thisLineObj, flush) != TCL_OK) { @@ -3138,6 +3158,64 @@ WriteIDAT( /* *---------------------------------------------------------------------- * + * WriteExtraChunks -- + * + * Writes an sBIT and a tEXt chunks to the PNG image, describing a bunch + * of not very important metadata that many readers seem to need anyway. + * + * Results: + * TCL_OK, or TCL_ERROR if the write fails. + * + * Side effects: + * None + * + *---------------------------------------------------------------------- + */ + +static int +WriteExtraChunks( + Tcl_Interp *interp, + PNGImage *pngPtr) +{ + static const unsigned char sBIT_contents[] = { + 8, 8, 8, 8 + }; + Tcl_DString buf; + + /* + * Each byte of each channel is always significant; we always write RGBA + * images with 8 bits per channel as that is what the photo image's basic + * data model is. + */ + + if (WriteChunk(interp, pngPtr, CHUNK_sBIT, sBIT_contents, 4) != TCL_OK) { + return TCL_ERROR; + } + + /* + * Say that it is Tk that made the PNG. Note that we *need* the NUL at the + * end of "Software" to be transferred; do *not* change the length + * parameter to -1 there! + */ + + Tcl_DStringInit(&buf); + Tcl_DStringAppend(&buf, "Software", 9); + Tcl_DStringAppend(&buf, "Tk Toolkit v", -1); + Tcl_DStringAppend(&buf, TK_PATCH_LEVEL, -1); + if (WriteChunk(interp, pngPtr, CHUNK_tEXt, + (unsigned char *) Tcl_DStringValue(&buf), + Tcl_DStringLength(&buf)) != TCL_OK) { + Tcl_DStringFree(&buf); + return TCL_ERROR; + } + Tcl_DStringFree(&buf); + + return TCL_OK; +} + +/* + *---------------------------------------------------------------------- + * * EncodePNG -- * * This function handles the entirety of writing a PNG file (or data) @@ -3235,6 +3313,15 @@ EncodePNG( } /* + * Write out the extra chunks containing metadata that is of interest to + * other programs more than us. + */ + + if (WriteExtraChunks(interp, pngPtr) == TCL_ERROR) { + return TCL_ERROR; + } + + /* * Write out the image pixels in the IDAT (data) chunk. */ |