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Make gif transparent color to be transparent black

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Change it from transparent white to transparent black, which matches
the transparent color assumed in Webp dispose-to-background method.

Also pre-multiply background colors before comparison in anim_diff,
just as what is done with regular pixel values.

Change-Id: I5a790522df21619c666ce499f73e42294ed276f2
(cherry picked from commit 43bd895879)
This commit is contained in:
hui su 2016-09-01 15:11:44 -07:00 committed by James Zern
parent 9871335fc8
commit 7ec9552c22
3 changed files with 18 additions and 4 deletions
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18
examples/anim_diff.c
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@ -110,6 +110,20 @@ static int CompareValues(uint32_t a, uint32_t b, const char* output_str) {
return 1;
}
static int CompareBackgroundColor(uint32_t bg1, uint32_t bg2, int premultiply) {
if (premultiply) {
const int alpha1 = (bg1 >> 24) & 0xff;
const int alpha2 = (bg2 >> 24) & 0xff;
if (alpha1 == 0 && alpha2 == 0) return 1;
}
if (bg1 != bg2) {
fprintf(stderr, "Background color mismatch: 0x%08x vs 0x%08x\n",
bg1, bg2);
return 0;
}
return 1;
}
// Note: As long as frame durations and reconstructed frames are identical, it
// is OK for other aspects like offsets, dispose/blend method to vary.
static int CompareAnimatedImagePair(const AnimatedImage* const img1,
@ -131,8 +145,8 @@ static int CompareAnimatedImagePair(const AnimatedImage* const img1,
if (is_multi_frame_image) { // Checks relevant for multi-frame images only.
ok = CompareValues(img1->loop_count, img2->loop_count,
"Loop count mismatch") && ok;
ok = CompareValues(img1->bgcolor, img2->bgcolor,
"Background color mismatch") && ok;
ok = CompareBackgroundColor(img1->bgcolor, img2->bgcolor,
premultiply) && ok;
}
for (i = 0; i < img1->num_frames; ++i) {

2
examples/anim_util.c
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@ -396,7 +396,7 @@ static uint32_t GetBackgroundColorGIF(GifFileType* gif) {
const ColorMapObject* const color_map = gif->SColorMap;
if (transparent_index != NO_TRANSPARENT_COLOR &&
gif->SBackGroundColor == transparent_index) {
return 0x00ffffff; // Special case: transparent white.
return 0x00000000; // Special case: transparent black.
} else if (color_map == NULL || color_map->Colors == NULL
|| gif->SBackGroundColor >= color_map->ColorCount) {
return 0xffffffff; // Invalid: assume white.

2
examples/gifdec.c
View File

@ -21,7 +21,7 @@
#include "webp/encode.h"
#include "webp/mux_types.h"
#define GIF_TRANSPARENT_COLOR 0x00ffffff
#define GIF_TRANSPARENT_COLOR 0x00000000
#define GIF_WHITE_COLOR 0xffffffff
#define GIF_TRANSPARENT_MASK 0x01
#define GIF_DISPOSE_MASK 0x07