ImageBrush can apply a source image of a different pixel type than the target

src/ImageSharp.Drawing/Processing/ImageBrush.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Buffers;
+
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
@@ -37,8 +38,14 @@ namespace SixLabors.ImageSharp.Processing
             GraphicsOptions options)
             where TPixel : struct, IPixel<TPixel>
         {
-            Image<TPixel> specificImage = (Image<TPixel>)this.image;
-            return new ImageBrushApplicator<TPixel>(source, specificImage.Frames.RootFrame, region, options);
+            if (this.image is Image<TPixel> specificImage)
+            {
+                return new ImageBrushApplicator<TPixel>(source, specificImage, region, options, false);
+            }
+
+            specificImage = this.image.CloneAs<TPixel>();
+            
+            return new ImageBrushApplicator<TPixel>(source, specificImage, region, options, true);
         }
 
         /// <summary>
@@ -47,10 +54,11 @@ namespace SixLabors.ImageSharp.Processing
         private class ImageBrushApplicator<TPixel> : BrushApplicator<TPixel>
             where TPixel : struct, IPixel<TPixel>
         {
-            /// <summary>
-            /// The source image.
-            /// </summary>
-            private readonly ImageFrame<TPixel> source;
+            private ImageFrame<TPixel> sourceFrame;
+
+            private Image<TPixel> sourceImage;
+
+            private readonly bool shouldDisposeImage;
 
             /// <summary>
             /// The y-length.
@@ -79,10 +87,18 @@ namespace SixLabors.ImageSharp.Processing
             /// <param name="image">The image.</param>
             /// <param name="region">The region.</param>
             /// <param name="options">The options</param>
-            public ImageBrushApplicator(ImageFrame<TPixel> target, ImageFrame<TPixel> image, RectangleF region, GraphicsOptions options)
+            /// <param name="shouldDisposeImage">Whether to dispose the image on disposal of the applicator.</param>
+            public ImageBrushApplicator(
+                ImageFrame<TPixel> target,
+                Image<TPixel> image,
+                RectangleF region,
+                GraphicsOptions options,
+                bool shouldDisposeImage)
                 : base(target, options)
             {
-                this.source = image;
+                this.sourceImage = image;
+                this.sourceFrame = image.Frames.RootFrame;
+                this.shouldDisposeImage = shouldDisposeImage;
                 this.xLength = image.Width;
                 this.yLength = image.Height;
                 this.offsetY = (int)MathF.Max(MathF.Floor(region.Top), 0);
@@ -103,13 +119,19 @@ namespace SixLabors.ImageSharp.Processing
                 {
                     int srcX = (x - this.offsetX) % this.xLength;
                     int srcY = (y - this.offsetY) % this.yLength;
-                    return this.source[srcX, srcY];
+                    return this.sourceFrame[srcX, srcY];
                 }
             }
 
             /// <inheritdoc />
             public override void Dispose()
             {
+                if (this.shouldDisposeImage)
+                {
+                    this.sourceImage?.Dispose();
+                    this.sourceImage = null;
+                    this.sourceFrame = null;
+                }
             }
 
             /// <inheritdoc />
@@ -124,7 +146,7 @@ namespace SixLabors.ImageSharp.Processing
 
                     int sourceY = (y - this.offsetY) % this.yLength;
                     int offsetX = x - this.offsetX;
-                    Span<TPixel> sourceRow = this.source.GetPixelRowSpan(sourceY);
+                    Span<TPixel> sourceRow = this.sourceFrame.GetPixelRowSpan(sourceY);
 
                     for (int i = 0; i < scanline.Length; i++)
                     {
@@ -137,7 +159,7 @@ namespace SixLabors.ImageSharp.Processing
 
                     Span<TPixel> destinationRow = this.Target.GetPixelRowSpan(y).Slice(x, scanline.Length);
                     this.Blender.Blend(
-                        this.source.Configuration,
+                        this.sourceFrame.Configuration,
                         destinationRow,
                         destinationRow,
                         overlaySpan,

src/ImageSharp/Image.cs

@@ -87,6 +87,23 @@ namespace SixLabors.ImageSharp
             EncodeVisitor visitor = new EncodeVisitor(encoder, stream);
             this.AcceptVisitor(visitor);
         }
+        
+        /// <summary>
+        /// Returns a copy of the image in the given pixel format.
+        /// </summary>
+        /// <typeparam name="TPixel2">The pixel format.</typeparam>
+        /// <returns>The <see cref="Image{TPixel2}"/></returns>
+        public Image<TPixel2> CloneAs<TPixel2>()
+            where TPixel2 : struct, IPixel<TPixel2> => this.CloneAs<TPixel2>(this.Configuration);
+
+        /// <summary>
+        /// Returns a copy of the image in the given pixel format.
+        /// </summary>
+        /// <typeparam name="TPixel2">The pixel format.</typeparam>
+        /// <param name="configuration">The configuration providing initialization code which allows extending the library.</param>
+        /// <returns>The <see cref="Image{TPixel2}"/>.</returns>
+        public abstract Image<TPixel2> CloneAs<TPixel2>(Configuration configuration)
+            where TPixel2 : struct, IPixel<TPixel2>;
 
         /// <summary>
         /// Accept a <see cref="IImageVisitor"/>.

src/ImageSharp/Image{TPixel}.cs

@@ -153,22 +153,13 @@ namespace SixLabors.ImageSharp
             return new Image<TPixel>(configuration, this.Metadata.DeepClone(), clonedFrames);
         }
 
-        /// <summary>
-        /// Returns a copy of the image in the given pixel format.
-        /// </summary>
-        /// <typeparam name="TPixel2">The pixel format.</typeparam>
-        /// <returns>The <see cref="Image{TPixel2}"/></returns>
-        public Image<TPixel2> CloneAs<TPixel2>()
-            where TPixel2 : struct, IPixel<TPixel2> => this.CloneAs<TPixel2>(this.Configuration);
-
         /// <summary>
         /// Returns a copy of the image in the given pixel format.
         /// </summary>
         /// <typeparam name="TPixel2">The pixel format.</typeparam>
         /// <param name="configuration">The configuration providing initialization code which allows extending the library.</param>
         /// <returns>The <see cref="Image{TPixel2}"/>.</returns>
-        public Image<TPixel2> CloneAs<TPixel2>(Configuration configuration)
-            where TPixel2 : struct, IPixel<TPixel2>
+        public override Image<TPixel2> CloneAs<TPixel2>(Configuration configuration)
         {
             IEnumerable<ImageFrame<TPixel2>> clonedFrames = this.Frames.Select(x => x.CloneAs<TPixel2>(configuration));
             return new Image<TPixel2>(configuration, this.Metadata.DeepClone(), clonedFrames);

tests/ImageSharp.Tests/Drawing/DrawImageTests.cs

@@ -175,5 +175,7 @@ namespace SixLabors.ImageSharp.Tests.Drawing
                 }
             }
         }
+
+        
     }
 }

tests/ImageSharp.Tests/Drawing/FillImageBrushTests.cs

@@ -32,5 +32,24 @@ namespace SixLabors.ImageSharp.Tests.Drawing
                 }
             }
         }
+        
+        [Theory]
+        [WithTestPatternImages(200, 200, PixelTypes.Rgba32 | PixelTypes.Bgra32)]
+        public void UseBrushOfDifferentPixelType<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            byte[] data = TestFile.Create(TestImages.Png.Ducky).Bytes;
+            using (Image<TPixel> background = provider.GetImage())
+            using (Image overlay = provider.PixelType == PixelTypes.Rgba32
+                                       ? (Image)Image.Load<Bgra32>(data)
+                                       : Image.Load<Rgba32>(data))
+            {
+                var brush = new ImageBrush(overlay);
+                background.Mutate(c => c.Fill(brush));
+
+                background.DebugSave(provider, appendSourceFileOrDescription : false);
+                background.CompareToReferenceOutput(provider, appendSourceFileOrDescription: false);
+            }
+        }
     }
 }

tests/ImageSharp.Tests/TestUtilities/ImagingTestCaseUtility.cs

@@ -152,21 +152,19 @@ namespace SixLabors.ImageSharp.Tests
         /// <summary>
         /// Encodes image by the format matching the required extension, than saves it to the recommended output file.
         /// </summary>
-        /// <typeparam name="TPixel">The pixel format of the image</typeparam>
         /// <param name="image">The image instance</param>
         /// <param name="extension">The requested extension</param>
         /// <param name="encoder">Optional encoder</param>
         /// <param name="appendPixelTypeToFileName">A value indicating whether to append the pixel type to the test output file name</param>
         /// <param name="appendSourceFileOrDescription">A boolean indicating whether to append <see cref="ITestImageProvider.SourceFileOrDescription"/> to the test output file name.</param>
         /// <param name="testOutputDetails">Additional information to append to the test output file name</param>
-        public string SaveTestOutputFile<TPixel>(
-            Image<TPixel> image,
+        public string SaveTestOutputFile(
+            Image image,
             string extension = null,
             IImageEncoder encoder = null,
             object testOutputDetails = null,
             bool appendPixelTypeToFileName = true,
             bool appendSourceFileOrDescription = true)
-            where TPixel : struct, IPixel<TPixel>
         {
             string path = this.GetTestOutputFileName(
                 extension,

tests/ImageSharp.Tests/TestUtilities/TestImageExtensions.cs

@@ -55,17 +55,16 @@ namespace SixLabors.ImageSharp.Tests
                     });
         }
 
-        public static Image<TPixel> DebugSave<TPixel>(
-            this Image<TPixel> image,
+        public static void DebugSave(
+            this Image image,
             ITestImageProvider provider,
             FormattableString testOutputDetails,
             string extension = "png",
             bool appendPixelTypeToFileName = true,
             bool appendSourceFileOrDescription = true,
             IImageEncoder encoder = null)
-            where TPixel : struct, IPixel<TPixel>
         {
-            return image.DebugSave(
+            image.DebugSave(
                 provider,
                 (object)testOutputDetails,
                 extension,
@@ -77,7 +76,6 @@ namespace SixLabors.ImageSharp.Tests
         /// <summary>
         /// Saves the image only when not running in the CI server.
         /// </summary>
-        /// <typeparam name="TPixel">The pixel format</typeparam>
         /// <param name="image">The image</param>
         /// <param name="provider">The image provider</param>
         /// <param name="testOutputDetails">Details to be concatenated to the test output file, describing the parameters of the test.</param>
@@ -85,15 +83,14 @@ namespace SixLabors.ImageSharp.Tests
         /// <param name="appendPixelTypeToFileName">A boolean indicating whether to append the pixel type to the  output file name.</param>
         /// <param name="appendSourceFileOrDescription">A boolean indicating whether to append <see cref="ITestImageProvider.SourceFileOrDescription"/> to the test output file name.</param>
         /// <param name="encoder">Custom encoder to use.</param>
-        public static Image<TPixel> DebugSave<TPixel>(
-            this Image<TPixel> image,
+        public static Image DebugSave(
+            this Image image,
             ITestImageProvider provider,
             object testOutputDetails = null,
             string extension = "png",
             bool appendPixelTypeToFileName = true,
             bool appendSourceFileOrDescription = true,
             IImageEncoder encoder = null)
-            where TPixel : struct, IPixel<TPixel>
         {
             if (TestEnvironment.RunsOnCI)
             {
@@ -111,37 +108,34 @@ namespace SixLabors.ImageSharp.Tests
             return image;
         }
 
-        public static Image<TPixel> DebugSave<TPixel>(
-            this Image<TPixel> image,
+        public static void DebugSave(
+            this Image image,
             ITestImageProvider provider,
             IImageEncoder encoder,
             FormattableString testOutputDetails,
             bool appendPixelTypeToFileName = true)
-            where TPixel : struct, IPixel<TPixel>
         {
-            return image.DebugSave(provider, encoder, (object)testOutputDetails, appendPixelTypeToFileName);
+            image.DebugSave(provider, encoder, (object)testOutputDetails, appendPixelTypeToFileName);
         }
 
         /// <summary>
         /// Saves the image only when not running in the CI server.
         /// </summary>
-        /// <typeparam name="TPixel">The pixel format</typeparam>
         /// <param name="image">The image</param>
         /// <param name="provider">The image provider</param>
         /// <param name="encoder">The image encoder</param>
         /// <param name="testOutputDetails">Details to be concatenated to the test output file, describing the parameters of the test.</param>
         /// <param name="appendPixelTypeToFileName">A boolean indicating whether to append the pixel type to the  output file name.</param>
-        public static Image<TPixel> DebugSave<TPixel>(
-            this Image<TPixel> image,
+        public static void DebugSave(
+            this Image image,
             ITestImageProvider provider,
             IImageEncoder encoder,
             object testOutputDetails = null,
             bool appendPixelTypeToFileName = true)
-            where TPixel : struct, IPixel<TPixel>
         {
             if (TestEnvironment.RunsOnCI)
             {
-                return image;
+                return;
             }
 
             // We are running locally then we want to save it out
@@ -150,7 +144,6 @@ namespace SixLabors.ImageSharp.Tests
                 encoder: encoder,
                 testOutputDetails: testOutputDetails,
                 appendPixelTypeToFileName: appendPixelTypeToFileName);
-            return image;
         }
 
         public static Image<TPixel> DebugSaveMultiFrame<TPixel>(

tests/Images/External

@@ -1 +1 @@
-Subproject commit 55c250ab80f7f9fc26208b9b9d9590cbe8012446
+Subproject commit 9d1d9dd53755007ee812907f64304d1925c6a91a