Add restriction to samplers.

Former-commit-id: a1f5890e16408916332a4aa3e6cb0454554a9964
Former-commit-id: 01019e4c20cb33666ac5407482ee77d77a9632a2
Former-commit-id: d6f42c3a126e0817a6840d3eccf9f62faf5696ba

src/ImageProcessorCore/ImageExtensions.cs

@@ -10,6 +10,8 @@ namespace ImageProcessorCore
 
     using Formats;
 
+    using ImageProcessorCore.Samplers;
+
     /// <summary>
     /// Exstension methods for the <see cref="Image"/> type.
     /// </summary>
@@ -89,7 +91,7 @@ namespace ImageProcessorCore
         /// <param name="height">The target image height.</param>
         /// <param name="processors">Any processors to apply to the image.</param>
         /// <returns>The <see cref="Image"/>.</returns>
-        public static Image Process(this Image source, int width, int height, params IImageProcessor[] processors)
+        public static Image Process(this Image source, int width, int height, params IImageSampler[] processors)
         {
             return Process(source, width, height, source.Bounds, default(Rectangle), processors);
         }
@@ -113,12 +115,12 @@ namespace ImageProcessorCore
         /// </param>
         /// <param name="processors">Any processors to apply to the image.</param>
         /// <returns>The <see cref="Image"/>.</returns>
-        public static Image Process(this Image source, int width, int height, Rectangle sourceRectangle, Rectangle targetRectangle, params IImageProcessor[] processors)
+        public static Image Process(this Image source, int width, int height, Rectangle sourceRectangle, Rectangle targetRectangle, params IImageSampler[] processors)
         {
             // ReSharper disable once LoopCanBeConvertedToQuery
-            foreach (IImageProcessor filter in processors)
+            foreach (IImageSampler sampler in processors)
             {
-                source = PerformAction(source, false, (sourceImage, targetImage) => filter.Apply(targetImage, sourceImage, width, height, targetRectangle, sourceRectangle));
+                source = PerformAction(source, false, (sourceImage, targetImage) => sampler.Apply(targetImage, sourceImage, width, height, targetRectangle, sourceRectangle));
             }
 
             return source;

src/ImageProcessorCore/Samplers/Crop.cs

@@ -10,7 +10,7 @@ namespace ImageProcessorCore.Samplers
     /// <summary>
     /// Provides methods to allow the cropping of an image.
     /// </summary>
-    public class Crop : ParallelImageProcessor
+    public class Crop : ImageSampler
     {
         /// <inheritdoc/>
         protected override void Apply(ImageBase target, ImageBase source, Rectangle targetRectangle, Rectangle sourceRectangle, int startY, int endY)

src/ImageProcessorCore/Samplers/EntropyCrop.cs

@@ -14,7 +14,7 @@ namespace ImageProcessorCore.Samplers
     /// Provides methods to allow the cropping of an image to preserve areas of highest
     /// entropy.
     /// </summary>
-    public class EntropyCrop : ParallelImageProcessor
+    public class EntropyCrop : ImageSampler
     {
         /// <summary>
         /// The rectangle for cropping

src/ImageProcessorCore/Samplers/IImageSampler.cs

@@ -0,0 +1,14 @@
+// <copyright file="IImageSampler.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageProcessorCore.Samplers
+{
+    /// <summary>
+    /// Acts as a marker for generic parameters that require an image sampler.
+    /// </summary>
+    public interface IImageSampler : IImageProcessor
+    {
+    }
+}

src/ImageProcessorCore/Samplers/ImageSampler.cs

@@ -0,0 +1,15 @@
+// <copyright file="ImageSampler.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageProcessorCore.Samplers
+{
+    /// <summary>
+    /// Applies sampling methods to an image. 
+    /// All processors requiring resampling or resizing should inherit from this.
+    /// </summary>
+    public abstract class ImageSampler : ParallelImageProcessor, IImageSampler
+    {
+    }
+}

src/ImageProcessorCore/Samplers/ImageSampleExtensions.cs → src/ImageProcessorCore/Samplers/ImageSamplerExtensions.cs

@@ -1,4 +1,4 @@
-// <copyright file="ImageSampleExtensions.cs" company="James Jackson-South">
+// <copyright file="ImageSamplerExtensions.cs" company="James Jackson-South">
 // Copyright (c) James Jackson-South and contributors.
 // Licensed under the Apache License, Version 2.0.
 // </copyright>
@@ -8,7 +8,7 @@ namespace ImageProcessorCore.Samplers
     /// <summary>
     /// Extensions methods for <see cref="Image"/> to apply samplers to the image.
     /// </summary>
-    public static class ImageSampleExtensions
+    public static class ImageSamplerExtensions
     {
         /// <summary>
         /// Crops an image to the given width and height.

src/ImageProcessorCore/Samplers/Resampler.cs

@@ -12,7 +12,7 @@ namespace ImageProcessorCore.Samplers
     /// <summary>
     /// Provides methods that allow the resampling of images using various algorithms.
     /// </summary>
-    public abstract class Resampler : ParallelImageProcessor
+    public abstract class Resampler : ImageSampler
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="Resampler"/> class.

tests/ImageProcessorCore.Tests/Processors/Filters/FilterTests.cs

@@ -74,10 +74,5 @@ namespace ImageProcessorCore.Tests
                 }
             }
         }
-
-        private void ProgressUpdate(object sender, ProgressEventArgs e)
-        {
-            Assert.InRange(e.RowsProcessed, 1, e.TotalRows);
-        }
     }
 }

tests/ImageProcessorCore.Tests/Processors/ProcessorTestBase.cs

@@ -9,6 +9,8 @@ namespace ImageProcessorCore.Tests
 {
     using System.Collections.Generic;
 
+    using Xunit;
+
     /// <summary>
     /// The processor test base.
     /// </summary>
@@ -29,5 +31,10 @@ namespace ImageProcessorCore.Tests
             "TestImages/Formats/Gif/rings.gif",
             //"TestImages/Formats/Gif/giphy.gif" // Perf: Enable for local testing only
         };
+        
+        protected void ProgressUpdate(object sender, ProgressEventArgs e)
+        {
+            Assert.InRange(e.RowsProcessed, 1, e.TotalRows);
+        }
     }
 }

tests/ImageProcessorCore.Tests/Processors/Samplers/SamplerTests.cs

@@ -30,7 +30,7 @@
                 //{ "Welch", new WelchResampler() }
             };
 
-        public static readonly TheoryData<string, IImageProcessor> Samplers = new TheoryData<string, IImageProcessor>
+        public static readonly TheoryData<string, IImageSampler> Samplers = new TheoryData<string, IImageSampler>
         {
              { "Resize", new Resize(new BicubicResampler()) },
              { "Crop", new Crop() }
@@ -47,7 +47,7 @@
 
         [Theory]
         [MemberData("Samplers")]
-        public void SampleImage(string name, IImageProcessor processor)
+        public void SampleImage(string name, IImageSampler processor)
         {
             if (!Directory.Exists("TestOutput/Sample"))
             {
@@ -64,7 +64,8 @@
                     using (FileStream output = File.OpenWrite($"TestOutput/Sample/{ Path.GetFileName(filename) }"))
                     {
                         processor.OnProgress += this.ProgressUpdate;
-                        image.Process(image.Width / 2, image.Height / 2, processor).Save(output);
+                        image = image.Process(image.Width / 2, image.Height / 2, processor);
+                        image.Save(output);
                         processor.OnProgress -= this.ProgressUpdate;
                     }
 
@@ -269,10 +270,5 @@
 
             Assert.Equal(result, expected);
         }
-
-        private void ProgressUpdate(object sender, ProgressEventArgs e)
-        {
-            Assert.InRange(e.RowsProcessed, 1, e.TotalRows);
-        }
     }
 }