add Image brush

src/ImageSharp/Drawing/Brushes/ImageBrush.cs

@@ -0,0 +1,108 @@
+// <copyright file="ImageBrush.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageSharp.Drawing.Brushes
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Numerics;
+    using System.Threading.Tasks;
+    using Processors;
+
+    /// <summary>
+    /// Provides an implementaion of a solid brush for painting with repeating images.
+    /// </summary>
+    public class ImageBrush : ImageBrush<Color, uint>
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ImageBrush" /> class.
+        /// </summary>
+        /// <param name="color">The color.</param>
+        public ImageBrush(IImageBase<Color, uint> image)
+            : base(image)
+        {
+        }
+    }
+
+    /// <summary>
+    /// Provides an implementaion of a solid brush for painting solid color areas.
+    /// </summary>
+    /// <typeparam name="TColor">The type of the color.</typeparam>
+    /// <typeparam name="TPacked">The type of the packed.</typeparam>
+    public class ImageBrush<TColor, TPacked> : IBrush<TColor, TPacked>
+            where TColor : struct, IPackedPixel<TPacked>
+            where TPacked : struct
+    {
+        private readonly IImageBase<TColor, TPacked> image;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="SolidBrush{TColor, TPacked}"/> class.
+        /// </summary>
+        /// <param name="color">The color.</param>
+        public ImageBrush(IImageBase<TColor, TPacked> image)
+        {
+            this.image = image;
+        }
+
+        /// <summary>
+        /// Creates the applicator for this brush.
+        /// </summary>
+        /// <param name="region">The region the brush will be applied to.</param>
+        /// <returns>
+        /// The brush applicator for this brush
+        /// </returns>
+        /// <remarks>
+        /// The <paramref name="region" /> when being applied to things like shapes would ussually be the
+        /// bounding box of the shape not necessarily the bounds of the whole image
+        /// </remarks>
+        public IBrushApplicator<TColor, TPacked> CreateApplicator(RectangleF region)
+        {
+            return new ImageBrushApplicator(this.image, region);
+        }
+
+        private class ImageBrushApplicator : IBrushApplicator<TColor, TPacked>
+        {
+            private readonly PixelAccessor<TColor, TPacked> source;
+            private readonly int yLength;
+            private readonly int xLength;
+            private readonly Vector2 offset;
+            private readonly float YOffset;
+
+            public ImageBrushApplicator(IImageBase<TColor, TPacked> image, RectangleF region)
+            {
+                this.source = image.Lock();
+                this.xLength = image.Width;
+                this.yLength = image.Height;
+                this.offset = new Vector2((float)Math.Max(Math.Floor(region.Top), 0),
+                                          (float)Math.Max(Math.Floor(region.Left), 0));
+            }
+
+            /// <summary>
+            /// Gets the color for a single pixel.
+            /// </summary>
+            /// <param name="point">The point.</param>
+            /// <returns>
+            /// The color
+            /// </returns>
+            public TColor GetColor(Vector2 point)
+            {
+                //offset the requested pixel by the value in the rectangle (the shapes position)
+                point = point - offset;
+                var x = (int)point.X % this.xLength;
+                var y = (int)point.Y % this.yLength;
+
+                return source[x, y];
+            }
+
+            /// <summary>
+            /// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
+            /// </summary>
+            public void Dispose()
+            {
+                source.Dispose();
+            }
+        }
+    }
+}

tests/ImageSharp.Tests/Drawing/SolidPolygonTests.cs

@@ -12,6 +12,7 @@ namespace ImageSharp.Tests.Drawing
     using System.IO;
     using System.Numerics;
     using Xunit;
+    using ImageSharp.Drawing.Brushes;
 
     public class SolidPolygonTests : FileTestBase
     {
@@ -77,6 +78,28 @@ namespace ImageSharp.Tests.Drawing
             }
         }
 
+        [Fact]
+        public void ImageShouldBeOverlayedByFilledPolygon_Image()
+        {
+            string path = CreateOutputDirectory("Drawing", "FilledPolygons");
+            var simplePath = new[] {
+                            new Vector2(10, 10),
+                            new Vector2(200, 150),
+                            new Vector2(50, 300)
+            };
+
+            var brush = new ImageBrush(Files[2].CreateImage());
+            var image = new Image(500, 500);
+
+            using (FileStream output = File.OpenWrite($"{path}/Image.png"))
+            {
+                image
+                    .BackgroundColor(Color.Blue)
+                    .FillPolygon(brush, simplePath)
+                    .Save(output);
+            }
+        }
+
         [Fact]
         public void ImageShouldBeOverlayedByFilledPolygonOpacity()
         {
@@ -87,7 +110,7 @@ namespace ImageSharp.Tests.Drawing
                             new Vector2(50, 300)
             };
             var color = new Color(Color.HotPink.R, Color.HotPink.G, Color.HotPink.B, 150);
-            
+
             var image = new Image(500, 500);
 
             using (FileStream output = File.OpenWrite($"{path}/Opacity.png"))