Refactor DrawImageProcessor<TPixelBg, TPixelFg>

src/ImageSharp/Processing/Processors/Convolution/GaussianBlurProcessor{TPixel}.cs

@@ -44,10 +44,9 @@ namespace SixLabors.ImageSharp.Processing.Processors.Convolution
         /// <inheritdoc/>
         protected override void OnFrameApply(ImageFrame<TPixel> source)
         {
-            using (var processor = new Convolution2PassProcessor<TPixel>(this.Configuration, this.KernelX, this.KernelY, false, this.Source, this.SourceRectangle))
+            using var processor = new Convolution2PassProcessor<TPixel>(this.Configuration, this.KernelX, this.KernelY, false, this.Source, this.SourceRectangle);
-            {
+
-                processor.Apply(source);
+            processor.Apply(source);
-            }
         }
     }
 }

src/ImageSharp/Processing/Processors/Convolution/GaussianSharpenProcessor{TPixel}.cs

@@ -44,10 +44,9 @@ namespace SixLabors.ImageSharp.Processing.Processors.Convolution
         /// <inheritdoc/>
         protected override void OnFrameApply(ImageFrame<TPixel> source)
         {
-            using (var processor = new Convolution2PassProcessor<TPixel>(this.Configuration, this.KernelX, this.KernelY, false, this.Source, this.SourceRectangle))
+            using var processor = new Convolution2PassProcessor<TPixel>(this.Configuration, this.KernelX, this.KernelY, false, this.Source, this.SourceRectangle);
-            {
+
-                processor.Apply(source);
+            processor.Apply(source);
-            }
         }
     }
 }

src/ImageSharp/Processing/Processors/Drawing/DrawImageProcessor{TPixelBg,TPixelFg}.cs

@@ -2,7 +2,9 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
+using System.Runtime.CompilerServices;
 using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 
 namespace SixLabors.ImageSharp.Processing.Processors.Drawing
@@ -100,15 +102,58 @@ namespace SixLabors.ImageSharp.Processing.Processors.Drawing
             ParallelRowIterator.IterateRows(
                 workingRect,
                 configuration,
-                rows =>
+                new RowIntervalAction(source, targetImage, blender, configuration, minX, width, locationY, targetX, this.Opacity));
+        }
+
+        /// <summary>
+        /// A <see langword="struct"/> implementing the draw logic for <see cref="DrawImageProcessor{TPixelBg,TPixelFg}"/>.
+        /// </summary>
+        private readonly struct RowIntervalAction : IRowIntervalAction
+        {
+            private readonly ImageFrame<TPixelBg> sourceFrame;
+            private readonly Image<TPixelFg> targetImage;
+            private readonly PixelBlender<TPixelBg> blender;
+            private readonly Configuration configuration;
+            private readonly int minX;
+            private readonly int width;
+            private readonly int locationY;
+            private readonly int targetX;
+            private readonly float opacity;
+
+            [MethodImpl(InliningOptions.ShortMethod)]
+            public RowIntervalAction(
+                ImageFrame<TPixelBg> sourceFrame,
+                Image<TPixelFg> targetImage,
+                PixelBlender<TPixelBg> blender,
+                Configuration configuration,
+                int minX,
+                int width,
+                int locationY,
+                int targetX,
+                float opacity)
+            {
+                this.sourceFrame = sourceFrame;
+                this.targetImage = targetImage;
+                this.blender = blender;
+                this.configuration = configuration;
+                this.minX = minX;
+                this.width = width;
+                this.locationY = locationY;
+                this.targetX = targetX;
+                this.opacity = opacity;
+            }
+
+            /// <inheritdoc/>
+            [MethodImpl(InliningOptions.ShortMethod)]
+            public void Invoke(in RowInterval rows)
+            {
+                for (int y = rows.Min; y < rows.Max; y++)
                 {
-                    for (int y = rows.Min; y < rows.Max; y++)
+                    Span<TPixelBg> background = this.sourceFrame.GetPixelRowSpan(y).Slice(this.minX, this.width);
-                    {
+                    Span<TPixelFg> foreground = this.targetImage.GetPixelRowSpan(y - this.locationY).Slice(this.targetX, this.width);
-                        Span<TPixelBg> background = source.GetPixelRowSpan(y).Slice(minX, width);
+                    this.blender.Blend<TPixelFg>(this.configuration, background, background, foreground, this.opacity);
-                        Span<TPixelFg> foreground = targetImage.GetPixelRowSpan(y - locationY).Slice(targetX, width);
+                }
-                        blender.Blend<TPixelFg>(configuration, background, background, foreground, this.Opacity);
+            }
-                    }
-                });
         }
     }
 }