Avalonia.Labs.GifImage - Certain GIFs aren't decoded right.

[ShadowMarker789]

Testing on Kick Emote Gifs, these GIFs do not load correctly.

E.g.:

Initially I thought it was a stream error but even taking that image as an AvaloniaResource did not permit it to be loaded correctly.

The image appears to be a normal GIF to me, is this wrong?

[emmauss]

Which Labs version are you using? I downloaded the gif, saved it and loaded it as an avalonia resource and works fine.

[ShadowMarker789]

Which Labs version are you using? I downloaded the gif, saved it and loaded it as an avalonia resource and works fine.

I was using Avalonia.Labs.Gif Nuget v 11.3.0

I may retest using master branch directly.

[ShadowMarker789]

I have found the issue!

When using a Stream source like a Memory Stream

The GifDecoder does not reset the Stream position to 0!

And InitializeGif gets called both when the Source is set, AND when the element is attached to the tree!

So the stream is read and advances, but when InitializeGif and GifDecoder gets called a SECOND time from the original same stream, the stream position is different! So it doesn't find the header because the stream isn't being reset!

[ShadowMarker789]

And confirmed, the reason this throws is that with an explicit stream source, not an Avalonia Resource Uri, it does not reset the stream and tries to decode the same gif twice from the same stream in succession - once when the source is set, and another time when the element is attached to the visual tree.

[emmauss]

Thank for checking this out. This looks like it'd be simple to fix. Would you be able to open a quick PR for it if you can make a reliable fix?