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Fix handling of weird GIF with canvas dimension 0x0

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Similarly to Chrome, we then use the first sub-rectangle
to set the canvas size.

Also: add check for too-large GIF dimensions (>MAX_CANVAS_SIZE)

Change-Id: Idce55f1e6f6982a8f0e082aac540e16b530e023e
This commit is contained in:
skal 2014-06-24 17:34:45 +02:00
parent a9ef7ef991
commit 1582e402fd
1 changed files with 45 additions and 15 deletions
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60
examples/gif2webp.c
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@ -103,12 +103,12 @@ static void Remap(const uint8_t* const src, const GifFileType* const gif,
static int ReadFrame(GifFileType* const gif, WebPFrameRect* const gif_rect,
WebPPicture* const webp_frame) {
WebPPicture sub_image;
const GifImageDesc image_desc = gif->Image;
const GifImageDesc* const image_desc = &gif->Image;
uint32_t* dst = NULL;
uint8_t* tmp = NULL;
int ok = 0;
WebPFrameRect rect = {
image_desc.Left, image_desc.Top, image_desc.Width, image_desc.Height
image_desc->Left, image_desc->Top, image_desc->Width, image_desc->Height
};
*gif_rect = rect;
@ -124,7 +124,7 @@ static int ReadFrame(GifFileType* const gif, WebPFrameRect* const gif_rect,
tmp = (uint8_t*)malloc(rect.width * sizeof(*tmp));
if (tmp == NULL) goto End;
if (image_desc.Interlace) { // Interlaced image.
if (image_desc->Interlace) { // Interlaced image.
// We need 4 passes, with the following offsets and jumps.
const int interlace_offsets[] = { 0, 4, 2, 1 };
const int interlace_jumps[] = { 8, 8, 4, 2 };
@ -404,16 +404,6 @@ int main(int argc, const char *argv[]) {
#endif
if (gif == NULL) goto End;
// Allocate current buffer
frame.width = gif->SWidth;
frame.height = gif->SHeight;
frame.use_argb = 1;
if (!WebPPictureAlloc(&frame)) goto End;
// Initialize cache
cache = WebPFrameCacheNew(frame.width, frame.height, kmin, kmax, allow_mixed);
if (cache == NULL) goto End;
mux = WebPMuxNew();
if (mux == NULL) {
fprintf(stderr, "ERROR: could not create a mux object.\n");
@ -429,8 +419,47 @@ int main(int argc, const char *argv[]) {
switch (type) {
case IMAGE_DESC_RECORD_TYPE: {
WebPFrameRect gif_rect;
GifImageDesc* const image_desc = &gif->Image;
if (!DGifGetImageDesc(gif)) goto End;
// Fix some broken GIF global headers that report
// 0 x 0 screen dimension.
if (is_first_frame) {
if (verbose) {
printf("Canvas screen: %d x %d\n", gif->SWidth, gif->SHeight);
}
if (gif->SWidth == 0 || gif->SHeight == 0) {
image_desc->Left = 0;
image_desc->Top = 0;
gif->SWidth = image_desc->Width;
gif->SHeight = image_desc->Height;
if (gif->SWidth <= 0 || gif->SHeight <= 0) {
goto End;
}
if (verbose) {
printf("Fixed canvas screen dimension to: %d x %d\n",
gif->SWidth, gif->SHeight);
}
}
// Allocate current buffer
frame.width = gif->SWidth;
frame.height = gif->SHeight;
frame.use_argb = 1;
if (!WebPPictureAlloc(&frame)) goto End;
WebPUtilClearPic(&frame, NULL);
// Initialize cache
cache = WebPFrameCacheNew(frame.width, frame.height,
kmin, kmax, allow_mixed);
if (cache == NULL) goto End;
}
// Some even more broken GIF can have sub-rect with zero width/height.
if (image_desc->Width == 0 || image_desc->Height == 0) {
image_desc->Width = gif->SWidth;
image_desc->Height = gif->SHeight;
}
if (!ReadFrame(gif, &gif_rect, &frame)) {
goto End;
}
@ -486,7 +515,6 @@ int main(int argc, const char *argv[]) {
fprintf(stderr, "GIF decode warning: invalid background color "
"index. Assuming white background.\n");
}
WebPUtilClearPic(&frame, NULL);
}
break;
}
@ -501,7 +529,9 @@ int main(int argc, const char *argv[]) {
if (data == NULL) goto End; // Loop count sub-block missing.
if (data[0] != 3 && data[1] != 1) break; // wrong size/marker
anim.loop_count = data[2] | (data[3] << 8);
if (verbose) fprintf(stderr, "Loop count: %d\n", anim.loop_count);
if (verbose) {
fprintf(stderr, "Loop count: %d\n", anim.loop_count);
}
} else { // An extension containing metadata.
// We only store the first encountered chunk of each type, and
// only if requested by the user.