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gif2webp: Bgcolor fix for a special case

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When transparent color index and background color index are same,
we should set background color to 0x00ffffff (transparent).

For this, we delay setting the background color until we have read the
first frame.

Change-Id: I443609b9c7697a2b94a66992460cff8465b3c127
This commit is contained in:
Urvang Joshi 2013-03-21 15:52:02 -07:00
parent 5f25c396ab
commit a5ebd143d6
1 changed files with 23 additions and 18 deletions
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35
examples/gif2webp.c
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@ -117,14 +117,17 @@ static int ReadSubImage(GifFileType* gif, WebPPicture* pic, WebPPicture* view) {
return ok;
}
static int GetColorFromIndex(const ColorMapObject* const color_map, GifWord idx,
uint32_t* const argb) {
assert(color_map != NULL && color_map->Colors != NULL);
if (idx >= color_map->ColorCount) {
return 0; // Invalid index.
static int GetBackgroundColor(const ColorMapObject* const color_map,
GifWord bgcolor_idx, uint32_t* const bgcolor) {
if (transparent_index != -1 && bgcolor_idx == transparent_index) {
*bgcolor = TRANSPARENT_COLOR; // Special case.
return 1;
} else if (color_map == NULL || color_map->Colors == NULL
|| bgcolor_idx >= color_map->ColorCount) {
return 0; // Invalid color map or index.
} else {
const GifColorType color = color_map->Colors[idx];
*argb = (0xff << 24)
const GifColorType color = color_map->Colors[bgcolor_idx];
*bgcolor = (0xff << 24)
| (color.Red << 16)
| (color.Green << 8)
| (color.Blue << 0);
@ -199,6 +202,7 @@ int main(int argc, const char *argv[]) {
WebPMuxFrameInfo frame;
WebPMuxAnimParams anim = { WHITE_COLOR, 0 };
int is_first_frame = 1;
int done;
int c;
int quiet = 0;
@ -283,14 +287,6 @@ int main(int argc, const char *argv[]) {
picture.custom_ptr = &memory;
if (!WebPPictureAlloc(&picture)) goto End;
if (gif->SColorMap != NULL &&
!GetColorFromIndex(gif->SColorMap, gif->SBackGroundColor,
&anim.bgcolor)) {
fprintf(stderr, "GIF decode warning: invalid background color index. "
"Assuming white background.\n");
}
ClearPicture(&picture, anim.bgcolor);
mux = WebPMuxNew();
if (mux == NULL) {
fprintf(stderr, "ERROR: could not create a mux object.\n");
@ -379,6 +375,15 @@ int main(int argc, const char *argv[]) {
: WEBP_MUX_DISPOSE_NONE;
}
transparent_index = (flags & GIF_TRANSPARENT_MASK) ? data[4] : -1;
if (is_first_frame) {
if (!GetBackgroundColor(gif->SColorMap, gif->SBackGroundColor,
&anim.bgcolor)) {
fprintf(stderr, "GIF decode warning: invalid background color "
"index. Assuming white background.\n");
}
ClearPicture(&picture, anim.bgcolor);
is_first_frame = 0;
}
break;
}
case PLAINTEXT_EXT_FUNC_CODE: {