Fix gif frame reuse #40125
Fix gif frame reuse #40125
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This reintroduces flutter/flutter#61150 (comment) |
lib/ui/painting/multi_frame_codec.cc
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| @@ -115,17 +115,17 @@ sk_sp<DlImage> MultiFrameCodec::State::GetNextFrameImage( | |||
| << "Frame " << nextFrameIndex_ << " depends on frame " | |||
| << requiredFrameIndex | |||
| << " and no required frames are cached. Using blank slate instead."; | |||
| return nullptr; | |||
| } else if (lastRequiredFrameIndex_ != requiredFrameIndex) { | |||
| FML_DLOG(INFO) << "Required frame " << requiredFrameIndex | |||
| << " is not cached. Using blank slate instead."; | |||
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So this path ends up getting hit for the problem GIF? It would seem like we're possibly drawing the wrong frame here, and we're just getting lucky that the frame still looks OK while rendering the wrong frame?
It's common for GIFs/WEBPs/APNGs to keep using one frame as the backdrop across the whole animation. That's not really possible with the way we've written multiframecodec today.
Not sure if we should fix it in this PR, but this comment should at least be updated since it's inaccurate with this change. Maybe just drop the "Using blank slate instead" since that doesn't always happen.
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It doesn't get hit becaues of the else if.
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I'mg oing to remove it entirely though.
lib/ui/painting/multi_frame_codec.cc
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| @@ -115,17 +115,17 @@ sk_sp<DlImage> MultiFrameCodec::State::GetNextFrameImage( | |||
| << "Frame " << nextFrameIndex_ << " depends on frame " | |||
| << requiredFrameIndex | |||
| << " and no required frames are cached. Using blank slate instead."; | |||
| return nullptr; | |||
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It would be more graceful to just draw the frame against the zeroed bitmap in this case instead of failing the frame.
lib/ui/painting/multi_frame_codec.cc
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| } | ||
| // Copy the previous frame's output buffer into the current frame as the | ||
| // starting point. | ||
| if (lastRequiredFrame_->getPixels() && |
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I think adding requiredFrameIndex != SkCodec::kNoFrame to the conditional would keep both fixes working.
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I did this a bit differently by making the condition below that updates the "keep" frame every time once we first encounter a keep frame.
I think this is fine because Skia's documentation on this parameter says that the last required frame is the earliest frame, and you can use any frame from that one to the last one. See https://github.com/google/skia/blob/7b18d6c5c676abcb274a8dc6b2896c8c2f667a63/include/codec/SkCodec.h#L640
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Added a regression test for the webp issue, and have a patch that now correctly handles both the funky gif and the funky webp. |
Adds a golden test that hopefully works cross platform 😇
Fixes flutter/flutter#122134
See also #31098