From cce2265f7ec1560ed5567d549f634f63e8ebbf4d Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Sat, 30 Jul 2016 10:53:14 +1000
Subject: [PATCH] Blend

Former-commit-id: ff1aec34e42b49f728dfd7f370f709c48be34762
Former-commit-id: ee75403396e61e34b0d97760ee36634973d5a5ec
Former-commit-id: 326da67dbfdb92272ab63c08e30a9e85904f7e60
---
 src/ImageProcessorCore/Filters/Blend.cs       | 62 +++++++++++++
 .../Filters/Processors/BlendProcessor.cs      | 93 +++++++++++++++++++
 .../Processors/Filters/BlendTest.cs           | 44 +++++++++
 3 files changed, 199 insertions(+)
 create mode 100644 src/ImageProcessorCore/Filters/Blend.cs
 create mode 100644 src/ImageProcessorCore/Filters/Processors/BlendProcessor.cs
 create mode 100644 tests/ImageProcessorCore.Tests/Processors/Filters/BlendTest.cs

diff --git a/src/ImageProcessorCore/Filters/Blend.cs b/src/ImageProcessorCore/Filters/Blend.cs
new file mode 100644
index 000000000..96f8f60cd
--- /dev/null
+++ b/src/ImageProcessorCore/Filters/Blend.cs
@@ -0,0 +1,62 @@
+// <copyright file="Blend.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>-------------------------------------------------------------------------------------------------------------------
+
+namespace ImageProcessorCore
+{
+    using Processors;
+
+    /// <summary>
+    /// Extension methods for the <see cref="Image"/> type.
+    /// </summary>
+    public static partial class ImageExtensions
+    {
+        /// <summary>
+        /// Combines the given image together with the current one by blending their pixels.
+        /// </summary>
+        /// <param name="source">The image this method extends.</param>
+        /// <param name="image">The image to blend with the currently processing image.</param>
+        /// <typeparam name="T">The pixel format.</typeparam>
+        /// <typeparam name="TP">The packed format. <example>long, float.</example></typeparam>
+        /// <param name="percent">The opacity of the image image to blend. Must be between 0 and 100.</param>
+        /// <param name="progressHandler">A delegate which is called as progress is made processing the image.</param>
+        /// <returns>The <see cref="Image{T,TP}"/>.</returns>
+        public static Image<T, TP> Blend<T, TP>(this Image<T, TP> source, ImageBase<T, TP> image, int percent = 50, ProgressEventHandler progressHandler = null)
+            where T : IPackedVector<TP>
+            where TP : struct
+        {
+            return Blend(source, image, percent, source.Bounds, progressHandler);
+        }
+
+        /// <summary>
+        /// Combines the given image together with the current one by blending their pixels.
+        /// </summary>
+        /// <param name="source">The image this method extends.</param>
+        /// <param name="image">The image to blend with the currently processing image.</param>
+        /// <typeparam name="T">The pixel format.</typeparam>
+        /// <typeparam name="TP">The packed format. <example>long, float.</example></typeparam>
+        /// <param name="percent">The opacity of the image image to blend. Must be between 0 and 100.</param>
+        /// <param name="rectangle">
+        /// The <see cref="Rectangle"/> structure that specifies the portion of the image object to alter.
+        /// </param>
+        /// <param name="progressHandler">A delegate which is called as progress is made processing the image.</param>
+        /// <returns>The <see cref="Image{T,TP}"/>.</returns>
+        public static Image<T, TP> Blend<T, TP>(this Image<T, TP> source, ImageBase<T, TP> image, int percent, Rectangle rectangle, ProgressEventHandler progressHandler = null)
+            where T : IPackedVector<TP>
+            where TP : struct
+        {
+            BlendProcessor<T, TP> processor = new BlendProcessor<T, TP>(image, percent);
+            processor.OnProgress += progressHandler;
+
+            try
+            {
+                return source.Process(rectangle, processor);
+            }
+            finally
+            {
+                processor.OnProgress -= progressHandler;
+            }
+        }
+    }
+}
diff --git a/src/ImageProcessorCore/Filters/Processors/BlendProcessor.cs b/src/ImageProcessorCore/Filters/Processors/BlendProcessor.cs
new file mode 100644
index 000000000..56c754729
--- /dev/null
+++ b/src/ImageProcessorCore/Filters/Processors/BlendProcessor.cs
@@ -0,0 +1,93 @@
+// <copyright file="BlendProcessor.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageProcessorCore.Processors
+{
+    using System.Numerics;
+    using System.Threading.Tasks;
+
+    /// <summary>
+    /// Combines two images together by blending the pixels.
+    /// </summary>
+    /// <typeparam name="T">The pixel format.</typeparam>
+    /// <typeparam name="TP">The packed format. <example>long, float.</example></typeparam>
+    public class BlendProcessor<T, TP> : ImageProcessor<T, TP>
+        where T : IPackedVector<TP>
+        where TP : struct
+    {
+        /// <summary>
+        /// The image to blend.
+        /// </summary>
+        private readonly ImageBase<T, TP> blend;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="BlendProcessor"/> class.
+        /// </summary>
+        /// <param name="image">
+        /// The image to blend with the currently processing image. 
+        /// Disposal of this image is the responsibility of the developer.
+        /// </param>
+        /// <param name="alpha">The opacity of the image to blend. Between 0 and 100.</param>
+        public BlendProcessor(ImageBase<T, TP> image, int alpha = 100)
+        {
+            Guard.MustBeBetweenOrEqualTo(alpha, 0, 100, nameof(alpha));
+            this.blend = image;
+            this.Value = alpha;
+        }
+
+        /// <summary>
+        /// Gets the alpha percentage value.
+        /// </summary>
+        public int Value { get; }
+
+        /// <inheritdoc/>
+        protected override void Apply(ImageBase<T, TP> target, ImageBase<T, TP> source, Rectangle targetRectangle, Rectangle sourceRectangle, int startY, int endY)
+        {
+            int sourceY = sourceRectangle.Y;
+            int sourceBottom = sourceRectangle.Bottom;
+            int startX = sourceRectangle.X;
+            int endX = sourceRectangle.Right;
+            Rectangle bounds = this.blend.Bounds;
+            float alpha = this.Value / 100f;
+
+            using (IPixelAccessor<T, TP> toBlendPixels = this.blend.Lock())
+            using (IPixelAccessor<T, TP> sourcePixels = source.Lock())
+            using (IPixelAccessor<T, TP> targetPixels = target.Lock())
+            {
+                Parallel.For(
+                    startY,
+                    endY,
+                    y =>
+                        {
+                            if (y >= sourceY && y < sourceBottom)
+                            {
+                                for (int x = startX; x < endX; x++)
+                                {
+                                    Vector4 color = sourcePixels[x, y].ToVector4();
+
+                                    if (bounds.Contains(x, y))
+                                    {
+                                        Vector4 blendedColor = toBlendPixels[x, y].ToVector4();
+
+                                        if (blendedColor.W > 0)
+                                        {
+                                            // Lerping colors is dependent on the alpha of the blended color
+                                            float alphaFactor = alpha > 0 ? alpha : blendedColor.W;
+                                            color = Vector4.Lerp(color, blendedColor, alphaFactor);
+                                        }
+                                    }
+
+                                    T packed = default(T);
+                                    packed.PackVector(color);
+                                    targetPixels[x, y] = packed;
+                                }
+
+                                this.OnRowProcessed();
+                            }
+                        });
+            }
+        }
+    }
+}
diff --git a/tests/ImageProcessorCore.Tests/Processors/Filters/BlendTest.cs b/tests/ImageProcessorCore.Tests/Processors/Filters/BlendTest.cs
new file mode 100644
index 000000000..2aa6ce044
--- /dev/null
+++ b/tests/ImageProcessorCore.Tests/Processors/Filters/BlendTest.cs
@@ -0,0 +1,44 @@
+// <copyright file="BlendTest.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageProcessorCore.Tests
+{
+    using System.IO;
+
+    using Xunit;
+
+    public class BlendTest : FileTestBase
+    {
+        [Fact]
+        public void ImageShouldApplyBlendFilter()
+        {
+            const string path = "TestOutput/Blend";
+            if (!Directory.Exists(path))
+            {
+                Directory.CreateDirectory(path);
+            }
+
+            Image blend;
+            using (FileStream stream = File.OpenRead("TestImages/Formats/Bmp/Car.bmp"))
+            {
+                blend = new Image(stream);
+            }
+
+            foreach (string file in Files)
+            {
+                using (FileStream stream = File.OpenRead(file))
+                {
+                    string filename = Path.GetFileName(file);
+                    Image image = new Image(stream);
+                    using (FileStream output = File.OpenWrite($"{path}/{filename}"))
+                    {
+                        image.Blend(blend)
+                             .Save(output);
+                    }
+                }
+            }
+        }
+    }
+}
\ No newline at end of file