Added PixelShaderExtensions class

src/ImageSharp/Processing/Extensions/PixelShaderExtensions.cs

@@ -0,0 +1,36 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using SixLabors.ImageSharp.Processing.Delegates;
+using SixLabors.ImageSharp.Processing.Processors;
+using SixLabors.Primitives;
+
+namespace SixLabors.ImageSharp.Processing
+{
+    /// <summary>
+    /// Defines extension methods that allow the application of user defined pixel shaders to an <see cref="Image"/>.
+    /// </summary>
+    public static class PixelShaderExtensions
+    {
+        /// <summary>
+        /// Applies a user defined pixel shader to the image.
+        /// </summary>
+        /// <param name="source">The image this method extends.</param>
+        /// <param name="pixelShader">The user defined pixel shader to use to modify images.</param>
+        /// <returns>The <see cref="IImageProcessingContext"/> to allow chaining of operations.</returns>
+        public static IImageProcessingContext ApplyPixelShaderProcessor(this IImageProcessingContext source, PixelShader pixelShader)
+            => source.ApplyProcessor(new DelegatePixelShaderProcessor(pixelShader));
+
+        /// <summary>
+        /// Applies a user defined pixel shader to the image.
+        /// </summary>
+        /// <param name="source">The image this method extends.</param>
+        /// <param name="pixelShader">The user defined pixel shader to use to modify images.</param>
+        /// <param name="rectangle">
+        /// The <see cref="Rectangle"/> structure that specifies the portion of the image object to alter.
+        /// </param>
+        /// <returns>The <see cref="IImageProcessingContext"/> to allow chaining of operations.</returns>
+        public static IImageProcessingContext BlackWhite(this IImageProcessingContext source, PixelShader pixelShader, Rectangle rectangle)
+            => source.ApplyProcessor(new DelegatePixelShaderProcessor(pixelShader), rectangle);
+    }
+}