From 5cd96d3bf007a7816691f6b9c2c843118d95a884 Mon Sep 17 00:00:00 2001 From: SpaceCheetah Date: Mon, 1 Apr 2024 17:03:25 -0700 Subject: [PATCH] re-add comment --- src/ImageSharp/Formats/Png/PngDecoderCore.cs | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/src/ImageSharp/Formats/Png/PngDecoderCore.cs b/src/ImageSharp/Formats/Png/PngDecoderCore.cs index 222fe8ed34..77edf2d9ad 100644 --- a/src/ImageSharp/Formats/Png/PngDecoderCore.cs +++ b/src/ImageSharp/Formats/Png/PngDecoderCore.cs @@ -654,7 +654,8 @@ internal sealed class PngDecoderCore : IImageDecoderInternals { frame = image.Frames.AddFrame(previousFrame ?? image.Frames.RootFrame); - // If restoring to before first frame, restore to background. Same if first frame (previousFrameControl null). + // If the first `fcTL` chunk uses a `dispose_op` of APNG_DISPOSE_OP_PREVIOUS it should be treated as APNG_DISPOSE_OP_BACKGROUND. + // So, if restoring to before first frame, clear entire area. Same if first frame (previousFrameControl null). if (previousFrameControl == null || (previousFrame is null && previousFrameControl.Value.DisposeOperation == PngDisposalMethod.RestoreToPrevious)) { Buffer2DRegion pixelRegion = frame.PixelBuffer.GetRegion();