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[devel] Implementation of premultiplied alpha support: png_set_alpha_mode

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(libpng-manual.txt still to be updated, see png.h for documentation.)
This commit is contained in:
John Bowler
2011-05-07 21:00:28 -05:00
committed by Glenn Randers-Pehrson
parent af855e415d
commit d273ad2d0f
12 changed files with 2128 additions and 607 deletions
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25
png.c
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@@ -586,17 +586,17 @@ png_convert_to_rfc1123(png_structp png_ptr, png_const_timep ptime)
if (pos < (sizeof png_ptr->time_buffer)-1)\
png_ptr->time_buffer[pos++] = (ch)
APPEND_NUMBER(PNG_NUMBER_FORMAT_u, ptime->day % 32);
APPEND_NUMBER(PNG_NUMBER_FORMAT_u, (unsigned)ptime->day % 32);
APPEND(' ');
APPEND_STRING(short_months[(ptime->month - 1) % 12]);
APPEND(' ');
APPEND_NUMBER(PNG_NUMBER_FORMAT_u, ptime->year);
APPEND(' ');
APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, ptime->hour % 24);
APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->hour % 24);
APPEND(':');
APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, ptime->minute % 60);
APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->minute % 60);
APPEND(':');
APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, ptime->second % 61);
APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->second % 61);
APPEND_STRING(" +0000"); /* This reliably terminates the buffer */
# undef APPEND
@@ -2322,8 +2322,9 @@ png_build_gamma_table(png_structp png_ptr, int bit_depth)
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_BACKGROUND) | PNG_RGB_TO_GRAY))
if (png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY))
{
png_build_8bit_table(png_ptr, &png_ptr->gamma_to_1,
png_reciprocal(png_ptr->gamma));
@@ -2332,7 +2333,7 @@ png_build_gamma_table(png_structp png_ptr, int bit_depth)
png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
png_ptr->gamma/* Probably doing rgb_to_gray */);
}
#endif /* PNG_READ_BACKGROUND_SUPPORTED || PNG_RGB_TO_GRAY_SUPPORTED */
#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
}
else
{
@@ -2391,7 +2392,12 @@ png_build_gamma_table(png_structp png_ptr, int bit_depth)
png_ptr->gamma_shift = shift;
#ifdef PNG_16BIT_SUPPORTED
if (png_ptr->transformations & (PNG_16_TO_8 | PNG_BACKGROUND))
/* NOTE: prior to 1.5.3 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)
#endif
png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift,
png_ptr->screen_gamma > 0 ? png_product2(png_ptr->gamma,
@@ -2405,8 +2411,9 @@ png_build_gamma_table(png_structp png_ptr, int bit_depth)
#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_BACKGROUND | PNG_RGB_TO_GRAY))
if (png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY))
{
png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift,
png_reciprocal(png_ptr->gamma));
@@ -2419,7 +2426,7 @@ png_build_gamma_table(png_structp png_ptr, int bit_depth)
png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
png_ptr->gamma/* Probably doing rgb_to_gray */);
}
#endif /* PNG_READ_BACKGROUND_SUPPORTED || PNG_RGB_TO_GRAY_SUPPORTED */
#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
}
}
#endif /* READ_GAMMA */