More progress toward a working swizzler

src/ImageSharp/Processing/Processors/Transforms/ISwizzler.cs

@@ -8,11 +8,16 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
     /// </summary>
     public interface ISwizzler
     {
+        /// <summary>
+        /// Gets the size of the image after transformation.
+        /// </summary>
+        Size DestinationSize { get; }
+
         /// <summary>
         /// Applies the swizzle transformation to a given point.
         /// </summary>
         /// <param name="point">Point to transform.</param>
-        /// <returns>Transformed point.</returns>
+        /// <param name="newPoint">The transformed point.</param>
-        Point Transform(Point point);
+        void Transform(Point point, out Point newPoint);
     }
 }

src/ImageSharp/Processing/Processors/Transforms/SwizzleProcessor{TSwizzler,TPixel}.cs

@@ -1,31 +1,38 @@
 // Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
+using System;
 using SixLabors.ImageSharp.PixelFormats;
 
 namespace SixLabors.ImageSharp.Processing.Processors.Transforms
 {
-    internal class SwizzleProcessor<TSwizzler, TPixel> : ImageProcessor<TPixel>
+    internal class SwizzleProcessor<TSwizzler, TPixel> : TransformProcessor<TPixel>
         where TSwizzler : struct, ISwizzler
         where TPixel : unmanaged, IPixel<TPixel>
     {
         private readonly TSwizzler swizzler;
+        private readonly Size destinationSize;
 
         public SwizzleProcessor(Configuration configuration, TSwizzler swizzler, Image<TPixel> source, Rectangle sourceRectangle)
             : base(configuration, source, sourceRectangle)
         {
             this.swizzler = swizzler;
+            this.destinationSize = swizzler.DestinationSize;
         }
 
-        /// <inheritdoc/>
+        protected override Size GetDestinationSize()
-        protected override void OnFrameApply(ImageFrame<TPixel> source)
+            => this.destinationSize;
+
+        protected override void OnFrameApply(ImageFrame<TPixel> source, ImageFrame<TPixel> destination)
         {
-            for (int y = 0; y < source.Height; y++)
+            Point p = default;
+            Point newPoint;
+            for (p.Y = 0; p.Y < source.Height; p.Y++)
             {
-                var pixelRowSpan = source.GetPixelRowSpan(y);
+                for (p.X = 0; p.X < source.Width; p.X++)
-                for (int x = 0; x < source.Width; x++)
                 {
-                    var newPoint = this.swizzler.Transform(new Point(x, y));
+                    this.swizzler.Transform(p, out newPoint);
+                    destination[newPoint.X, newPoint.Y] = source[p.X, p.Y];
                 }
             }
         }

src/ImageSharp/Processing/Processors/Transforms/SwizzleProcessor{TSwizzler}.cs

@@ -17,7 +17,9 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
         /// </summary>
         /// <param name="swizzler">The swizzler operation.</param>
         public SwizzleProcessor(TSwizzler swizzler)
-            => this.Swizzler = swizzler;
+        {
+            this.Swizzler = swizzler;
+        }
 
         /// <summary>
         /// Gets the swizzler operation.
@@ -27,6 +29,6 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
         /// <inheritdoc />
         public IImageProcessor<TPixel> CreatePixelSpecificProcessor<TPixel>(Configuration configuration, Image<TPixel> source, Rectangle sourceRectangle)
             where TPixel : unmanaged, IPixel<TPixel>
-            => new SwizzleProcessor<TSwizzler, TPixel>(configuration, this, source, sourceRectangle);
+            => new SwizzleProcessor<TSwizzler, TPixel>(configuration, this.Swizzler, source, sourceRectangle);
     }
 }

tests/ImageSharp.Tests/Processing/Processors/Transforms/SwizzleTests.cs

@@ -0,0 +1,35 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.ImageSharp.Processing.Extensions.Transforms;
+using SixLabors.ImageSharp.Processing.Processors.Transforms;
+using Xunit;
+
+namespace SixLabors.ImageSharp.Tests.Processing.Processors.Transforms
+{
+    [GroupOutput("Transforms")]
+    public class SwizzleTests
+    {
+        private struct InvertXAndYSwizzler : ISwizzler
+        {
+            public Size DestinationSize => new Size(10, 10);
+
+            public void Transform(Point point, out Point newPoint)
+                => newPoint = new Point(point.Y, point.X);
+        }
+
+        [Theory]
+        [WithTestPatternImages(20, 37, PixelTypes.Rgba32)]
+        [WithTestPatternImages(53, 37, PixelTypes.Byte4)]
+        [WithTestPatternImages(17, 32, PixelTypes.Rgba32)]
+        public void InvertXAndYSwizzle<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            provider.RunValidatingProcessorTest(
+                ctx => ctx.Swizzle(default(InvertXAndYSwizzler)),
+                testOutputDetails: nameof(InvertXAndYSwizzler),
+                appendPixelTypeToFileName: false);
+        }
+    }
+}

tests/ImageSharp.Tests/Processing/Transforms/SwizzleTests.cs

@@ -11,21 +11,29 @@ namespace SixLabors.ImageSharp.Tests.Processing.Transforms
     {
         private struct InvertXAndYSwizzler : ISwizzler
         {
-            public Point Transform(Point point) => new Point(point.Y, point.X);
+            public Size DestinationSize => new Size(10, 10);
+
+            public void Transform(Point point, out Point newPoint)
+                => newPoint = new Point(point.Y, point.X);
         }
 
         [Fact]
-        public void RotateDegreesFloatRotateProcessorWithAnglesSet()
+        public void InvertXAndYSwizzlerSetsCorrectSizes()
         {
+            int width = 5;
+            int height = 10;
+
             this.operations.Swizzle(default(InvertXAndYSwizzler));
             SwizzleProcessor<InvertXAndYSwizzler> processor = this.Verify<SwizzleProcessor<InvertXAndYSwizzler>>();
 
-            // assert that pixels have been changed
+            Assert.Equal(processor.Swizzler.DestinationSize.Width, height);
+            Assert.Equal(processor.Swizzler.DestinationSize.Height, width);
 
             this.operations.Swizzle(default(InvertXAndYSwizzler));
-            SwizzleProcessor<InvertXAndYSwizzler> processor2 = this.Verify<SwizzleProcessor<InvertXAndYSwizzler>>();
+            SwizzleProcessor<InvertXAndYSwizzler> processor2 = this.Verify<SwizzleProcessor<InvertXAndYSwizzler>>(1);
 
-            // assert that pixels have been changed (i.e. back to original)
+            Assert.Equal(processor2.Swizzler.DestinationSize.Width, width);
+            Assert.Equal(processor2.Swizzler.DestinationSize.Height, height);
         }
     }
 }