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@ -240,8 +240,13 @@ internal sealed class PngDecoderCore : IImageDecoderInternals |
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currentFrameControl.Value, |
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cancellationToken); |
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previousFrame = currentFrame; |
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previousFrameControl = currentFrameControl; |
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// if current frame dispose is restore to previous, then from future frame's perspective, it never happened
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if (currentFrameControl.Value.DisposeOperation != PngDisposalMethod.RestoreToPrevious) |
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{ |
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previousFrame = currentFrame; |
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previousFrameControl = currentFrameControl; |
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} |
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break; |
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case PngChunkType.Data: |
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@ -639,18 +644,18 @@ internal sealed class PngDecoderCore : IImageDecoderInternals |
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out ImageFrame<TPixel> frame) |
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where TPixel : unmanaged, IPixel<TPixel> |
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{ |
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// We create a clone of the previous frame and add it.
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// We will overpaint the difference of pixels on the current frame to create a complete image.
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// This ensures that we have enough pixel data to process without distortion. #2450
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frame = image.Frames.AddFrame(previousFrame ?? image.Frames.RootFrame); |
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// If the first `fcTL` chunk uses a `dispose_op` of APNG_DISPOSE_OP_PREVIOUS it should be treated as APNG_DISPOSE_OP_BACKGROUND.
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if (previousFrameControl.DisposeOperation == PngDisposalMethod.RestoreToBackground |
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|| (previousFrame is null && previousFrameControl.DisposeOperation == PngDisposalMethod.RestoreToPrevious)) |
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// if restoring to before first frame, restore to background
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if (previousFrame is null && previousFrameControl.DisposeOperation == PngDisposalMethod.RestoreToPrevious) |
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{ |
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Buffer2DRegion<TPixel> pixelRegion = frame.PixelBuffer.GetRegion(); |
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pixelRegion.Clear(); |
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} |
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else if (previousFrameControl.DisposeOperation == PngDisposalMethod.RestoreToBackground) |
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{ |
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Rectangle restoreArea = previousFrameControl.Bounds; |
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Rectangle interest = Rectangle.Intersect(frame.Bounds(), restoreArea); |
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Buffer2DRegion<TPixel> pixelRegion = frame.PixelBuffer.GetRegion(interest); |
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Buffer2DRegion<TPixel> pixelRegion = frame.PixelBuffer.GetRegion(restoreArea); |
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pixelRegion.Clear(); |
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} |
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SpaceCheetah
2 years ago
