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[libpng16] Implement eXIf chunk support

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This commit is contained in:
Glenn Randers-Pehrson 2017-07-13 11:19:53 -05:00
parent 40943eb67a
commit 68cb0aaee3
17 changed files with 216 additions and 5 deletions
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1
ANNOUNCE
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@ -59,6 +59,7 @@ Version 1.6.31beta04 [July 11, 2017]
overflow' check that is on by default with -Wall -Wextra.
Version 1.6.31beta05 [July 11, 2017]
Added eXIf chunk support.
Send comments/corrections/commendations to png-mng-implement at lists.sf.net
(subscription required; visit

1
CHANGES
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@ -5889,6 +5889,7 @@ Version 1.6.31beta04 [July 11, 2017]
overflow' check that is on by default with -Wall -Wextra.
Version 1.6.31beta05 [July 11, 2017]
Added eXIf chunk support.
Send comments/corrections/commendations to png-mng-implement at lists.sf.net
(subscription required; visit

16
libpng-manual.txt
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@ -1453,6 +1453,11 @@ png_set_rgb_to_gray()).
the single transparent color for
non-paletted images (PNG_INFO_tRNS)
png_get_eXIf(png_ptr, info_ptr, &exif);
(PNG_INFO_eXIf)
exif - Exif profile (array of png_byte)
png_get_hIST(png_ptr, info_ptr, &hist);
(PNG_INFO_hIST)
@ -2498,6 +2503,7 @@ your application instead of by libpng, you can use
PNG_INFO_gAMA, PNG_INFO_sBIT,
PNG_INFO_cHRM, PNG_INFO_PLTE,
PNG_INFO_tRNS, PNG_INFO_bKGD,
PNG_INFO_eXIf,
PNG_INFO_hIST, PNG_INFO_pHYs,
PNG_INFO_oFFs, PNG_INFO_tIME,
PNG_INFO_pCAL, PNG_INFO_sRGB,
@ -3097,6 +3103,11 @@ width, height, bit_depth, and color_type must be the same in each call.
single transparent color for
non-paletted images (PNG_INFO_tRNS)
png_set_eXIf(png_ptr, info_ptr, exif);
hist - Exif profile (array of
png_byte) (PNG_INFO_eXIf)
png_set_hIST(png_ptr, info_ptr, hist);
hist - histogram of palette (array of
@ -5205,6 +5216,11 @@ is an error. Previously this requirement of the PNG specification was not
enforced, and the palette was always limited to 256 entries. An over-length
PLTE chunk found in an input PNG is silently truncated.
Starting with libpng-1.6.31, the eXIf chunk is supported. Libpng does not
attempt to decode the Exif profile; it simply returns a byte array
containing the profile to the calling application which must do its own
decoding.
XIII. Detecting libpng
The png_get_io_ptr() function has been present since libpng-0.88, has never

20
libpng.3
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@ -97,6 +97,8 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.6.31beta05
\fBpng_byte png_get_header_version (png_const_structp \fIpng_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_eXIf (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fI*exif\fP\fB);\fP
\fBpng_uint_32 png_get_hIST (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fI*hist\fP\fB);\fP
\fBpng_uint_32 png_get_iCCP (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_charpp \fP\fIname\fP\fB, int \fP\fI*compression_type\fP\fB, png_bytepp \fP\fIprofile\fP\fB, png_uint_32 \fI*proflen\fP\fB);\fP
@ -347,6 +349,8 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.6.31beta05
\fBvoid png_set_gray_to_rgb (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_set_eXIf (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fIexif\fP\fB);\fP
\fBvoid png_set_hIST (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fIhist\fP\fB);\fP
\fBvoid png_set_iCCP (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_const_charp \fP\fIname\fP\fB, int \fP\fIcompression_type\fP\fB, png_const_bytep \fP\fIprofile\fP\fB, png_uint_32 \fIproflen\fP\fB);\fP
@ -1963,6 +1967,11 @@ png_set_rgb_to_gray()).
the single transparent color for
non-paletted images (PNG_INFO_tRNS)
png_get_eXIf(png_ptr, info_ptr, &exif);
(PNG_INFO_eXIf)
exif - Exif profile (array of png_byte)
png_get_hIST(png_ptr, info_ptr, &hist);
(PNG_INFO_hIST)
@ -3008,6 +3017,7 @@ your application instead of by libpng, you can use
PNG_INFO_gAMA, PNG_INFO_sBIT,
PNG_INFO_cHRM, PNG_INFO_PLTE,
PNG_INFO_tRNS, PNG_INFO_bKGD,
PNG_INFO_eXIf,
PNG_INFO_hIST, PNG_INFO_pHYs,
PNG_INFO_oFFs, PNG_INFO_tIME,
PNG_INFO_pCAL, PNG_INFO_sRGB,
@ -3607,6 +3617,11 @@ width, height, bit_depth, and color_type must be the same in each call.
single transparent color for
non-paletted images (PNG_INFO_tRNS)
png_set_eXIf(png_ptr, info_ptr, exif);
hist - Exif profile (array of
png_byte) (PNG_INFO_eXIf)
png_set_hIST(png_ptr, info_ptr, hist);
hist - histogram of palette (array of
@ -5715,6 +5730,11 @@ is an error. Previously this requirement of the PNG specification was not
enforced, and the palette was always limited to 256 entries. An over-length
PLTE chunk found in an input PNG is silently truncated.
Starting with libpng-1.6.31, the eXIf chunk is supported. Libpng does not
attempt to decode the Exif profile; it simply returns a byte array
containing the profile to the calling application which must do its own
decoding.
.SH XIII. Detecting libpng
The png_get_io_ptr() function has been present since libpng-0.88, has never

10
png.c
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@ -615,6 +615,16 @@ png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,
}
#endif
#ifdef PNG_eXIf_SUPPORTED
/* Free any eXIf entry */
if (((mask & PNG_FREE_EXIF) & info_ptr->free_me) != 0)
{
png_free(png_ptr, info_ptr->exif);
info_ptr->exif = NULL;
info_ptr->valid &= ~PNG_INFO_eXIf;
}
#endif
#ifdef PNG_hIST_SUPPORTED
/* Free any hIST entry */
if (((mask & PNG_FREE_HIST) & info_ptr->free_me) != 0)

16
png.h
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@ -776,6 +776,7 @@ typedef png_unknown_chunk * * png_unknown_chunkpp;
#define PNG_INFO_sPLT 0x2000U /* ESR, 1.0.6 */
#define PNG_INFO_sCAL 0x4000U /* ESR, 1.0.6 */
#define PNG_INFO_IDAT 0x8000U /* ESR, 1.0.6 */
#define PNG_INFO_eXIf 0x10000U /* GR-P, 1.6.31 */
/* This is used for the transformation routines, as some of them
* change these values for the row. It also should enable using
@ -1788,7 +1789,8 @@ PNG_EXPORT(99, void, png_data_freer, (png_const_structrp png_ptr,
#define PNG_FREE_PLTE 0x1000U
#define PNG_FREE_TRNS 0x2000U
#define PNG_FREE_TEXT 0x4000U
#define PNG_FREE_ALL 0x7fffU
#define PNG_FREE_EXIF 0x8000U /* Added at libpng-1.6.31 */
#define PNG_FREE_ALL 0xffffU
#define PNG_FREE_MUL 0x4220U /* PNG_FREE_SPLT|PNG_FREE_TEXT|PNG_FREE_UNKN */
#ifdef PNG_USER_MEM_SUPPORTED
@ -2007,6 +2009,13 @@ PNG_FIXED_EXPORT(233, void, png_set_cHRM_XYZ_fixed, (png_const_structrp png_ptr,
png_fixed_point int_blue_Z))
#endif
#ifdef PNG_eXIf_SUPPORTED
PNG_EXPORT(246, png_uint_32, png_get_eXIf, (png_const_structrp png_ptr,
png_inforp info_ptr, png_bytep *exif));
PNG_EXPORT(247, void, png_set_eXIf, (png_const_structrp png_ptr,
png_inforp info_ptr, const png_bytep exif));
#endif
#ifdef PNG_gAMA_SUPPORTED
PNG_FP_EXPORT(137, png_uint_32, png_get_gAMA, (png_const_structrp png_ptr,
png_const_inforp info_ptr, double *file_gamma))
@ -2025,9 +2034,6 @@ PNG_FIXED_EXPORT(140, void, png_set_gAMA_fixed, (png_const_structrp png_ptr,
#ifdef PNG_hIST_SUPPORTED
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_const_structrp png_ptr,
png_inforp info_ptr, png_const_uint_16p hist));
#endif
@ -3253,7 +3259,7 @@ PNG_EXPORT(244, int, png_set_option, (png_structrp png_ptr, int option,
* one to use is one more than this.)
*/
#ifdef PNG_EXPORT_LAST_ORDINAL
PNG_EXPORT_LAST_ORDINAL(245);
PNG_EXPORT_LAST_ORDINAL(247);
#endif
#ifdef __cplusplus

18
pngget.c
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@ -773,6 +773,24 @@ png_get_sPLT(png_const_structrp png_ptr, png_inforp info_ptr,
}
#endif
#ifdef PNG_eXIf_SUPPORTED
png_uint_32 PNGAPI
png_get_eXIf(png_const_structrp png_ptr, png_inforp info_ptr,
png_bytep *exif)
{
png_debug1(1, "in %s retrieval function", "eXIf");
if (png_ptr != NULL && info_ptr != NULL &&
(info_ptr->valid & PNG_INFO_eXIf) != 0 && exif != NULL)
{
*exif = info_ptr->exif;
return (PNG_INFO_eXIf);
}
return (0);
}
#endif
#ifdef PNG_hIST_SUPPORTED
png_uint_32 PNGAPI
png_get_hIST(png_const_structrp png_ptr, png_inforp info_ptr,

5
pnginfo.h
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@ -185,6 +185,11 @@ defined(PNG_READ_BACKGROUND_SUPPORTED)
png_byte phys_unit_type; /* resolution type (see PNG_RESOLUTION_ below) */
#endif
#ifdef PNG_eXIf_SUPPORTED
int num_exif;
png_bytep exif;
#endif
#ifdef PNG_hIST_SUPPORTED
/* The hIST chunk contains the relative frequency or importance of the
* various palette entries, so that a viewer can intelligently select a

6
pngpriv.h
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@ -842,6 +842,7 @@
#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_eXIf PNG_U32(101, 88, 73, 102) /* registered July 2017 */
#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)
@ -1441,6 +1442,11 @@ 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_eXIf_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_handle_eXIf,(png_structrp png_ptr,
png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
#endif
#ifdef PNG_READ_gAMA_SUPPORTED
PNG_INTERNAL_FUNCTION(void,png_handle_gAMA,(png_structrp png_ptr,
png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);

38
pngrutil.c
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@ -2009,6 +2009,44 @@ png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
}
#endif
#ifdef PNG_READ_eXIf_SUPPORTED
void /* PRIVATE */
png_handle_eXIf(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
unsigned int i;
png_bytep eXIf_buf;
png_debug(1, "in png_handle_eXIf");
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_eXIf) != 0)
{
png_crc_finish(png_ptr, length);
png_chunk_benign_error(png_ptr, "duplicate");
return;
}
eXIf_buf = png_voidcast(png_bytep,
png_malloc_warn(png_ptr, length));
for (i = 0; i < length; i++)
{
png_byte buf[1];
png_crc_read(png_ptr, buf, 1);
eXIf_buf[i] = buf[0];
}
if (png_crc_finish(png_ptr, 0) != 0)
return;
info_ptr->num_exif = length;
png_set_eXIf(png_ptr, info_ptr, eXIf_buf);
}
#endif
#ifdef PNG_READ_hIST_SUPPORTED
void /* PRIVATE */
png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

33
pngset.c
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@ -134,6 +134,39 @@ png_set_cHRM_XYZ(png_const_structrp png_ptr, png_inforp info_ptr, double red_X,
#endif /* cHRM */
#ifdef PNG_eXIf_SUPPORTED
void PNGAPI
png_set_eXIf(png_const_structrp png_ptr, png_inforp info_ptr,
const png_bytep eXIf_buf)
{
int i;
png_debug1(1, "in %s storage function", "eXIf");
if (png_ptr == NULL || info_ptr == NULL)
return;
png_free_data(png_ptr, info_ptr, PNG_FREE_EXIF, 0);
info_ptr->exif = png_voidcast(png_bytep, png_malloc_warn(png_ptr,
info_ptr->num_exif));
if (info_ptr->exif == NULL)
{
png_warning(png_ptr, "Insufficient memory for eXIf chunk data");
return;
}
info_ptr->free_me |= PNG_FREE_EXIF;
for (i = 0; i < info_ptr->num_exif; i++)
info_ptr->exif[i] = eXIf_buf[i];
info_ptr->valid |= PNG_INFO_eXIf;
}
#endif /* eXIf */
#ifdef PNG_gAMA_SUPPORTED
void PNGFAPI
png_set_gAMA_fixed(png_const_structrp png_ptr, png_inforp info_ptr,

3
pngstruct.h
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@ -479,5 +479,8 @@ struct png_struct_def
png_colorspace colorspace;
#endif
#endif
/* New member added in libpng-1.6.30 */
int num_exif;
};
#endif /* PNGSTRUCT_H */

16
pngtest.c
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@ -1192,6 +1192,14 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
}
}
#endif
#ifdef PNG_eXIf_SUPPORTED
{
png_bytep exif;
if (png_get_eXIf(read_ptr, read_info_ptr, &exif) != 0)
png_set_eXIf(write_ptr, write_info_ptr, exif);
}
#endif
#ifdef PNG_hIST_SUPPORTED
{
png_uint_16p hist;
@ -1530,6 +1538,14 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
}
}
#endif
#ifdef PNG_eXIf_SUPPORTED
{
png_bytep exif;
if (png_get_eXIf(read_ptr, end_info_ptr, &exif) != 0)
png_set_eXIf(write_ptr, write_end_info_ptr, exif);
}
#endif
#ifdef PNG_tIME_SUPPORTED
{
png_timep mod_time;

31
pngwutil.c
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@ -1473,6 +1473,37 @@ png_write_bKGD(png_structrp png_ptr, png_const_color_16p back, int color_type)
}
#endif
#ifdef PNG_WRITE_eXIf_SUPPORTED
/* Write the Exif data */
void /* PRIVATE */
png_write_eXIf(png_structrp png_ptr, png_bytep exif, int num_exif)
{
int i;
png_byte buf[3];
png_debug(1, "in png_write_eXIf");
if (num_exif > (int)png_ptr->num_exif)
{
png_debug2(3, "num_exif = %d, png_ptr->num_exif = %d", num_exif,
png_ptr->num_exif);
png_warning(png_ptr, "Invalid number of exif bytes specified");
return;
}
png_write_chunk_header(png_ptr, png_eXIf, (png_uint_32)(num_exif));
for (i = 0; i < num_exif; i++)
{
buf[i] = exif[i];
png_write_chunk_data(png_ptr, buf, (png_size_t)1);
}
png_write_chunk_end(png_ptr);
}
#endif
#ifdef PNG_WRITE_hIST_SUPPORTED
/* Write the histogram */
void /* PRIVATE */

2
scripts/pnglibconf.dfa
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@ -741,6 +741,8 @@ setting IDAT_READ_SIZE default PNG_ZBUF_SIZE
# Ancillary chunks
chunk bKGD
chunk cHRM enables COLORSPACE
# enable eXIf only after chunk is approved
chunk eXIf
chunk gAMA enables GAMMA
chunk hIST
chunk iCCP enables COLORSPACE, GAMMA

3
scripts/pnglibconf.h.prebuilt
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@ -84,6 +84,7 @@
#define PNG_READ_USER_TRANSFORM_SUPPORTED
#define PNG_READ_bKGD_SUPPORTED
#define PNG_READ_cHRM_SUPPORTED
#define PNG_READ_eXIf_SUPPORTED
#define PNG_READ_gAMA_SUPPORTED
#define PNG_READ_hIST_SUPPORTED
#define PNG_READ_iCCP_SUPPORTED
@ -153,6 +154,7 @@
#define PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
#define PNG_WRITE_bKGD_SUPPORTED
#define PNG_WRITE_cHRM_SUPPORTED
#define PNG_WRITE_eXIf_SUPPORTED
#define PNG_WRITE_gAMA_SUPPORTED
#define PNG_WRITE_hIST_SUPPORTED
#define PNG_WRITE_iCCP_SUPPORTED
@ -170,6 +172,7 @@
#define PNG_WRITE_zTXt_SUPPORTED
#define PNG_bKGD_SUPPORTED
#define PNG_cHRM_SUPPORTED
#define PNG_eXIf_SUPPORTED
#define PNG_gAMA_SUPPORTED
#define PNG_hIST_SUPPORTED
#define PNG_iCCP_SUPPORTED

2
scripts/symbols.def
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@ -250,3 +250,5 @@ EXPORTS
png_get_palette_max @243
png_set_option @244
png_image_write_to_memory @245
png_get_eXIf @246
png_set_eXIf @247