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Merge pull request #7 from SDWebImage/bugfix_webp_animtion_render_logic 

Fix the Animated WebP render logic used by SDAnimatedImageView.
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DreamPiggy 2019-01-27 16:21:41 +08:00 committed by GitHub
parent 3f256df8c5 02595bc1d4
commit 3060843fe1
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1 changed files with 29 additions and 30 deletions
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39
SDWebImageWebPCoder/Classes/SDImageWebPCoder.m
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@ -795,44 +795,47 @@ static void FreeImageData(void *info, const void *data, size_t size) {
SDWebPCoderFrame *frame = _frames[index];
UIImage *image;
WebPIterator iter;
// Because Animated WebP supports dispose method, which means frames can based on previous canvas context. However, if we clear canvas and loop from the 0 index until the request index, it's harm for performance.
// But when one frame's dispose method is `WEBP_MUX_DISPOSE_BACKGROUND`, the canvas is cleared after the frame decoded. And subsequent frames are not effected by that frame.
// So, we calculate each frame's `blendFromIndex`. Then directly draw canvas from that index, instead of always from 0 index.
if (_currentBlendIndex + 1 == index) {
// If current blend index is equal to request index, normal serial process
// If the request index is subsequence of current blend index, it does not matter what dispose method is. The canvas is always ready.
_currentBlendIndex = index;
NSUInteger startIndex = index;
// libwebp's index start with 1
if (!WebPDemuxGetFrame(_demux, (int)(index + 1), &iter)) {
if (!WebPDemuxGetFrame(_demux, (int)(startIndex + 1), &iter)) {
WebPDemuxReleaseIterator(&iter);
return nil;
}
CGImageRef imageRef = [self sd_drawnWebpImageWithCanvas:_canvas iterator:iter colorSpace:_colorSpace];
if (!imageRef) {
return nil;
}
#if SD_UIKIT || SD_WATCH
image = [[UIImage alloc] initWithCGImage:imageRef scale:_scale orientation:UIImageOrientationUp];
#else
image = [[UIImage alloc] initWithCGImage:imageRef scale:_scale orientation:kCGImagePropertyOrientationUp];
#endif
CGImageRelease(imageRef);
} else {
// Else, this can happen when one image set to different imageViews or one loop end. So we should clear the shared cavans.
// Else, this can happen when one image set to different imageViews or one loop end. So we should clear the canvas. Then draw until the canvas is ready.
if (_currentBlendIndex != NSNotFound) {
CGContextClearRect(_canvas, CGRectMake(0, 0, _canvasWidth, _canvasHeight));
}
_currentBlendIndex = index;
// Then, loop from the blend from index, draw each of previous frames on the canvas.
// We use do while loop to call `WebPDemuxNextFrame`(fast), only (startIndex == endIndex) need to create image instance
// We use do while loop to call `WebPDemuxNextFrame`(fast), until the endIndex meet.
size_t startIndex = frame.blendFromIndex;
size_t endIndex = frame.index;
// libwebp's index start with 1
if (!WebPDemuxGetFrame(_demux, (int)(startIndex + 1), &iter)) {
WebPDemuxReleaseIterator(&iter);
return nil;
}
// Draw from range: [startIndex, endIndex)
if (endIndex > startIndex) {
do {
@autoreleasepool {
if ((size_t)iter.frame_num == endIndex) {
[self sd_blendWebpImageWithCanvas:_canvas iterator:iter colorSpace:_colorSpace];
} else {
}
} while ((size_t)iter.frame_num < (endIndex + 1) && WebPDemuxNextFrame(&iter));
}
}
// Now the canvas is ready, which respects of dispose method behavior. Just do normal decoding and produce image.
CGImageRef imageRef = [self sd_drawnWebpImageWithCanvas:_canvas iterator:iter colorSpace:_colorSpace];
if (!imageRef) {
return nil;
@ -843,10 +846,6 @@ static void FreeImageData(void *info, const void *data, size_t size) {
image = [[UIImage alloc] initWithCGImage:imageRef scale:_scale orientation:kCGImagePropertyOrientationUp];
#endif
CGImageRelease(imageRef);
}
}
} while ((size_t)iter.frame_num < (endIndex + 1) && WebPDemuxNextFrame(&iter));
}
WebPDemuxReleaseIterator(&iter);
return image;