add workaround for WIC JPEG bug

src/MagicScaler/Magic/InvertTransform.cs

@@ -0,0 +1,25 @@
+// Copyright © Clinton Ingram and Contributors
+// SPDX-License-Identifier: MIT
+
+using PhotoSauce.MagicScaler.Converters;
+
+namespace PhotoSauce.MagicScaler.Transforms;
+
+internal sealed class InvertTransform(PixelSource source) : ChainedPixelSource(source)
+{
+	protected override unsafe void CopyPixelsInternal(in PixelArea prc, int cbStride, int cbBufferSize, byte* pbBuffer)
+	{
+		Profiler.PauseTiming();
+		PrevSource.CopyPixels(prc, cbStride, cbBufferSize, pbBuffer);
+		Profiler.ResumeTiming();
+
+		nint cb = prc.Width * PrevSource.Format.BytesPerPixel;
+		for (int y = 0; y < prc.Height; y++)
+		{
+			InvertConverter.InvertLine(pbBuffer, cb);
+			pbBuffer += cbStride;
+		}
+	}
+
+	public override string ToString() => nameof(InvertTransform);
+}

src/MagicScaler/Magic/MagicTransforms.cs

@@ -421,6 +421,27 @@ public static void AddCropper(PipelineContext ctx)
 			return;
 		}
 
+		// Workaround for WIC JPEG decoder bug https://github.com/saucecontrol/wic-jpeg-bug
+		var src = ctx.Source;
+		if (src is WicFramePixelSource && src.Format == PixelFormat.Cmyk32 && src.Width != crop.Width)
+		{
+			using var buff = BufferPool.RentLocal<byte>(src.Width * src.Format.BytesPerPixel);
+			unsafe
+			{
+				fixed (byte* pBuff = buff)
+				{
+					src.CopyPixels(src.Area.Slice(crop.Y, 1), buff.Length, buff.Length, pBuff);
+					uint rpix = *((uint*)pBuff + crop.X);
+
+					src.CopyPixels(crop.Slice(0, 1), buff.Length, buff.Length, pBuff);
+					uint cpix = *(uint*)pBuff;
+
+					if (cpix == ~rpix)
+						ctx.Source = ctx.AddProfiler(new InvertTransform(src));
+				}
+			}
+		}
+
 		ctx.Source = ctx.AddProfiler(new CropTransform(ctx.Source, crop));
 	}