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[libpng16] Revised png_set_keep_unknown_chunks() so num_chunks < 0 means

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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.
This commit is contained in:
Glenn Randers-Pehrson
2012-06-16 13:26:28 -05:00
parent 0546e4e579
commit 96b917056d
8 changed files with 144 additions and 93 deletions
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38
contrib/gregbook/readpng2.c
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@@ -136,29 +136,23 @@ int readpng2_init(mainprog_info *mainprog_ptr)
* used, i.e., all chunks recognized by libpng except for IHDR, PLTE, IDAT,
* IEND, tRNS, bKGD, gAMA, and sRGB (small performance improvement) */
{
/* These byte strings were copied from png.h. If a future libpng
* version recognizes more chunks, add them to this list. If a
* future version of readpng2.c recognizes more chunks, delete them
* from this list. */
static /* const */ png_byte chunks_to_ignore[] = {
99, 72, 82, 77, '\0', /* cHRM */
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 */
116, 69, 88, 116, '\0', /* tEXt */
116, 73, 77, 69, '\0', /* tIME */
122, 84, 88, 116, '\0' /* zTXt */
};
/* These byte strings were copied from png.h. If a future version
* of readpng2.c recognizes more chunks, add them to this list.
*/
static PNG_CONST png_byte chunks_to_process[] = {
98, 75, 71, 68, '\0', /* bKGD */
103, 65, 77, 65, '\0', /* gAMA */
115, 82, 71, 66, '\0', /* sRGB */
};
png_set_keep_unknown_chunks(png_ptr, 1 /* PNG_HANDLE_CHUNK_NEVER */,
chunks_to_ignore, sizeof(chunks_to_ignore)/5);
/* Ignore all chunks except for IHDR, PLTE, tRNS, IDAT, and IEND */
png_set_keep_unknown_chunks(png_ptr, -1 /* PNG_HANDLE_CHUNK_NEVER */,
NULL, -1);
/* But do not ignore chunks in the "chunks_to_process" list */
png_set_keep_unknown_chunks(png_ptr,
0 /* PNG_HANDLE_CHUNK_AS_DEFAULT */, chunks_to_process,
sizeof(chunks_to_process)/5);
}
#endif /* PNG_HANDLE_AS_UNKNOWN_SUPPORTED */