SDImageAWebPCoder is driven by ImageIO...Which means:

How many frames here ?
What's the duration of this frame index ?

Is answered by ImageIO, not libwebp

Maybe it's bug of Apple, not SD...

Only reproduce in iOS 16.5 ? Did you test iOS 14/15 (ImageIO supports WebP from iOS 14+)

Only reproduce in iOS 16.5 ? Did you test iOS 14/15 (ImageIO supports WebP from iOS 14+)

I can also reproduce with iPhone SE 1st, which runs on iOS 14 and the test result is even worse. 😂

For this WebP. The CGImageSourceCreateImageAtIndex returned CGImage has already been broken...

Which means, seems there are no way for us (as a framework author) level can do to solve this. I guess this is bug in Apple's ImageIO, they does not follows the correct render of the dispose method in WebP standard.

See: https://developers.google.com/speed/webp/docs/riff_container. There are pseudocode for correcting render WebP (Which I implements in https://github.com/SDWebImage/SDWebImageWebPCoder)

Disposal method (D): 1 bit
Indicates how the current frame is to be treated after it has been displayed (before rendering the next frame) on the canvas:

0: Do not dispose. Leave the canvas as is.

1: Dispose to the background color. Fill the rectangle on the canvas covered by the current frame with the background color specified in the ['ANIM' Chunk](https://developers.google.com/speed/webp/docs/riff_container#anim_chunk).

My implementation follows the standard and it's not hard at all: https://github.com/SDWebImage/SDWebImageWebPCoder/blob/0.12.0/SDWebImageWebPCoder/Classes/SDImageWebPCoder.m#L488-L506

Maybe we need to update the limits of ImageIO's WebP here... https://github.com/SDWebImage/SDWebImage/wiki/Advanced-Usage#awebp-coder

I guess Apple made mistake on this render logic:

        BOOL shouldBlend = iter.blend_method == WEBP_MUX_BLEND;
        // If not blend, cover the target image rect. (firstly clear then draw)
        if (!shouldBlend) {
            CGContextClearRect(canvas, imageRect);
        }
        CGContextDrawImage(canvas, imageRect, imageRef);
        CGImageRelease(imageRef);

They seems to do like this (buggy):

        BOOL shouldBlend = iter.blend_method == WEBP_MUX_BLEND;
        if (!shouldBlend) {
            CGContextSetBlendMode(canvas, kCGBlendModeCopy); //. This is not correct actually, from real world example
        } else {
            CGContextSetBlendMode(canvas, kCGBlendModeNormal);
        }
        CGContextDrawImage(canvas, imageRect, imageRef);
        CGImageRelease(imageRef);

今天遇到一个webp问题, CollectionView 每个cell都展示webp动画, 一屏大概六个.

iOS 17.0.1
SDWebImageWebPCoder: 0.11.0
libwebp: 1.2.4
SDWebImage: 5.15.5
Xcode 15
正常渲染, 滑动collectionView不卡. (未使用SDWebImageAWebPCoder)

升级到最新的 5.18.2 (同时 libwebp: 1.2.4 -> 1.3.2, SDWebImageWebPCoder: 0.11.0 -> 0.13.0)
webp不展示, 但是隐约能看到有亮度的变化

使用SDWebImageAWebPCoder 可以展示, 但是滑动有点卡.

在想是继续保持5.15.5还是...

Provide a reproducable demo ?

@dreampiggy could this relate to #3356 ?

@dreampiggy could this relate to #3356 ?

Guess not ? This issue is about the different render result (still a valid UIImage/AnimatedImage obejct) but not "decode failed" (means, nil/null UIImage object)

But anyway, you can try to use the external libwebp based WebPCoder (See readme) and register as a coder to test again.

https://github.com/SDWebImage/SDWebImageWebPCoder#add-coder

Oh ok your image is valid. In my context image is not nil but not valid as it has width and/or height as 0:

                CGSize imageSize = image.size;
            if (imageSize.width == 0 || imageSize.height == 0) {
                NSString *description = image == nil ? @"Downloaded image decode failed" : @"Downloaded image has 0 pixels";
                NSError *error = [NSError errorWithDomain:SDWebImageErrorDomain code:SDWebImageErrorBadImageData userInfo:@{NSLocalizedDescriptionKey : description}];
                [self callCompletionBlockWithToken:token image:nil imageData:nil error:error finished:YES];
                }

Oh ok your image is valid. In my context image is not nil but not valid as it has width and/or height as 0:

                CGSize imageSize = image.size;
            if (imageSize.width == 0 || imageSize.height == 0) {
                NSString *description = image == nil ? @"Downloaded image decode failed" : @"Downloaded image has 0 pixels";
                NSError *error = [NSError errorWithDomain:SDWebImageErrorDomain code:SDWebImageErrorBadImageData userInfo:@{NSLocalizedDescriptionKey : description}];
                [self callCompletionBlockWithToken:token image:nil imageData:nil error:error finished:YES];
                }

That is just a stupid log. Even if image is nil it will still output log for "zero width or height". This is Objc code, "nil.width == 0" (any function call to nil returns 0)

Apple seems never fix this issue.

And this bug exists for Safari/WebKit as well. Community even use some tools to avoid 'dispose_method' and 'blend_mode' on iOS Webp, fallback to old school GIF workaround (each frame use a new canvas without previous status, unlike video, which is VP8 designed for), however this ugly workaround will cause the WebP size becomes larger😼

like this tool: https://bandisoft.com/honeycam/help/webp-iphone-compatible/

For now, if you care about your App's performance and bandwidth for WebP images, always choose that SDWebImageWebPCoder instead , even on iOS 17 (until Apple someday fix in their close-sourced decoder)

今天遇到一个webp问题， CollectionView 每个cell都展示webp动画， 一屏大概六个.

iOS 17.0.1 SDWebImageWebPCoder： 0.11.0 libwebp： 1.2.4 SDWebImage： 5.15.5 Xcode 15 正常渲染， 滑动collectionView不卡.（未使用SDWebImageAWebPCoder）

升级到最新的 5.18.2 （同时 libwebp： 1.2.4 -> 1.3.2， SDWebImageWebPCoder： 0.11.0 -> 0.13.0） webp不展示， 但是隐约能看到有亮度的变化

使用SDWebImageAWebPCoder 可以展示， 但是滑动有点卡.

在想是继续保持5.15.5还是...

是因为在 options 参数中 使用了 SDWebImageScaleDownLargeImages 导致的.... 删了 此参数就可以了