Merge pull request #309 from SixLabors/sw/image-brush-offsets

Ensure the negatively offset shapes are correctly offset the ImageBrush Texture during rendering.

Author: JimBobSquarePants

src/ImageSharp.Drawing/Processing/ImageBrush.cs

@@ -21,6 +21,11 @@ public class ImageBrush : Brush
     /// </summary>
     private readonly RectangleF region;
 
+    /// <summary>
+    /// The offet to apply to the source image while applying the imagebrush
+    /// </summary>
+    private readonly Point offset;
+
     /// <summary>
     /// Initializes a new instance of the <see cref="ImageBrush"/> class.
     /// </summary>
@@ -33,12 +38,44 @@ public ImageBrush(Image image)
     /// <summary>
     /// Initializes a new instance of the <see cref="ImageBrush"/> class.
     /// </summary>
-    /// <param name="image">The source image.</param>
-    /// <param name="region">The region of interest within the source image to draw.</param>
+    /// <param name="image">The image.</param>
+    /// <param name="offset">
+    /// An offset to apply the to image image while drawing apply the texture.
+    /// </param>
+    public ImageBrush(Image image, Point offset)
+        : this(image, image.Bounds, offset)
+    {
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ImageBrush"/> class.
+    /// </summary>
+    /// <param name="image">The image.</param>
+    /// <param name="region">
+    /// The region of interest.
+    /// This overrides any region used to initialize the brush applicator.
+    /// </param>
     public ImageBrush(Image image, RectangleF region)
+        : this(image, region, Point.Empty)
+    {
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ImageBrush"/> class.
+    /// </summary>
+    /// <param name="image">The image.</param>
+    /// <param name="region">
+    /// The region of interest.
+    /// This overrides any region used to initialize the brush applicator.
+    /// </param>
+    /// <param name="offset">
+    /// An offset to apply the to image image while drawing apply the texture.
+    /// </param>
+    public ImageBrush(Image image, RectangleF region, Point offset)
     {
         this.image = image;
         this.region = RectangleF.Intersect(image.Bounds, region);
+        this.offset = offset;
     }
 
     /// <inheritdoc />
@@ -64,11 +101,11 @@ public override BrushApplicator<TPixel> CreateApplicator<TPixel>(
     {
         if (this.image is Image<TPixel> specificImage)
         {
-            return new ImageBrushApplicator<TPixel>(configuration, options, source, specificImage, region, this.region, false);
+            return new ImageBrushApplicator<TPixel>(configuration, options, source, specificImage, region, this.region, this.offset, false);
         }
 
         specificImage = this.image.CloneAs<TPixel>();
-        return new ImageBrushApplicator<TPixel>(configuration, options, source, specificImage, region, this.region, true);
+        return new ImageBrushApplicator<TPixel>(configuration, options, source, specificImage, region, this.region, this.offset, true);
     }
 
     /// <summary>
@@ -107,6 +144,7 @@ private class ImageBrushApplicator<TPixel> : BrushApplicator<TPixel>
         /// <param name="image">The image.</param>
         /// <param name="targetRegion">The region of the target image we will be drawing to.</param>
         /// <param name="sourceRegion">The region of the source image we will be using to source pixels to draw from.</param>
+        /// <param name="offset">An offset to apply to the texture while drawing.</param>
         /// <param name="shouldDisposeImage">Whether to dispose the image on disposal of the applicator.</param>
         public ImageBrushApplicator(
             Configuration configuration,
@@ -115,6 +153,7 @@ public ImageBrushApplicator(
             Image<TPixel> image,
             RectangleF targetRegion,
             RectangleF sourceRegion,
+            Point offset,
             bool shouldDisposeImage)
             : base(configuration, options, target)
         {
@@ -124,8 +163,8 @@ public ImageBrushApplicator(
 
             this.sourceRegion = Rectangle.Intersect(image.Bounds, (Rectangle)sourceRegion);
 
-            this.offsetY = (int)MathF.Max(MathF.Floor(targetRegion.Top), 0);
-            this.offsetX = (int)MathF.Max(MathF.Floor(targetRegion.Left), 0);
+            this.offsetY = (int)MathF.Floor(targetRegion.Top) + offset.Y;
+            this.offsetX = (int)MathF.Floor(targetRegion.Left) + offset.X;
         }
 
         internal TPixel this[int x, int y]
@@ -166,14 +205,18 @@ public override void Apply(Span<float> scanline, int x, int y)
             Span<TPixel> overlaySpan = overlay.Memory.Span;
 
             int offsetX = x - this.offsetX;
-            int sourceY = ((y - this.offsetY) % this.sourceRegion.Height) + this.sourceRegion.Y;
+            int sourceY = ((((y - this.offsetY) % this.sourceRegion.Height) // clamp the number between -height and +height
+                        + this.sourceRegion.Height) % this.sourceRegion.Height) // clamp the number between 0  and +height
+                        + this.sourceRegion.Y;
             Span<TPixel> sourceRow = this.sourceFrame.PixelBuffer.DangerousGetRowSpan(sourceY);
 
             for (int i = 0; i < scanline.Length; i++)
             {
                 amountSpan[i] = scanline[i] * this.Options.BlendPercentage;
 
-                int sourceX = ((i + offsetX) % this.sourceRegion.Width) + this.sourceRegion.X;
+                int sourceX = ((((i + offsetX) % this.sourceRegion.Width) // clamp the number between -width and +width
+                        + this.sourceRegion.Width) % this.sourceRegion.Width) // clamp the number between 0  and +width
+                        + this.sourceRegion.X;
 
                 overlaySpan[i] = sourceRow[sourceX];
             }

src/ImageSharp.Drawing/Processing/Processors/Drawing/ClipPathProcessor{TPixel}.cs

@@ -39,7 +39,21 @@ public void Execute()
         // Use an image brush to apply cloned image as the source for filling the shape.
         // We pass explicit bounds to avoid the need to crop the clone;
         RectangleF bounds = this.definition.Region.Bounds;
-        var brush = new ImageBrush(clone, bounds);
+
+        // add some clamping offsets to the brush to account for the target drawing location due to the cloned image not fill the image as expected
+        var offsetX = 0;
+        var offsetY = 0;
+        if (bounds.X < 0)
+        {
+            offsetX = -(int)MathF.Floor(bounds.X);
+        }
+
+        if (bounds.Y < 0)
+        {
+            offsetY = -(int)MathF.Floor(bounds.Y);
+        }
+
+        var brush = new ImageBrush(clone, bounds, new Point(offsetX, offsetY));
 
         // Grab hold of an image processor that can fill paths with a brush to allow it to do the hard pixel pushing for us
         var processor = new FillPathProcessor(this.definition.Options, brush, this.definition.Region);

src/ImageSharp.Drawing/Processing/Processors/Drawing/FillPathProcessor.cs

@@ -56,11 +56,9 @@ public IImageProcessor<TPixel> CreatePixelSpecificProcessor<TPixel>(Configuratio
             var rect = (Rectangle)rectF;
             if (!this.Options.GraphicsOptions.Antialias || rectF == rect)
             {
-                var interest = Rectangle.Intersect(sourceRectangle, rect);
-
                 // Cast as in and back are the same or we are using anti-aliasing
                 return new FillProcessor(this.Options, this.Brush)
-                    .CreatePixelSpecificProcessor(configuration, source, interest);
+                    .CreatePixelSpecificProcessor(configuration, source, rect);
             }
         }
 

src/ImageSharp.Drawing/Processing/Processors/Drawing/FillPathProcessor{TPixel}.cs

@@ -74,7 +74,7 @@ protected override void OnFrameApply(ImageFrame<TPixel> source)
             subpixelCount = Math.Max(subpixelCount, graphicsOptions.AntialiasSubpixelDepth);
         }
 
-        using BrushApplicator<TPixel> applicator = brush.CreateApplicator(configuration, graphicsOptions, source, interest);
+        using BrushApplicator<TPixel> applicator = brush.CreateApplicator(configuration, graphicsOptions, source, this.bounds);
         int scanlineWidth = interest.Width;
         MemoryAllocator allocator = this.Configuration.MemoryAllocator;
         bool scanlineDirty = true;

src/ImageSharp.Drawing/Processing/Processors/Drawing/FillProcessor{TPixel}.cs

@@ -58,7 +58,7 @@ protected override void OnFrameApply(ImageFrame<TPixel> source)
             configuration,
             options,
             source,
-            interest);
+            this.SourceRectangle);
 
         amount.Memory.Span.Fill(1F);
 

tests/ImageSharp.Drawing.Tests/Drawing/ClipTests.cs

@@ -14,6 +14,7 @@ public class ClipTests
     [Theory]
     [WithBasicTestPatternImages(250, 350, PixelTypes.Rgba32, 0, 0, 0.5)]
     [WithBasicTestPatternImages(250, 350, PixelTypes.Rgba32, -20, -20, 0.5)]
+    [WithBasicTestPatternImages(250, 350, PixelTypes.Rgba32, -20, -100, 0.5)]
     [WithBasicTestPatternImages(250, 350, PixelTypes.Rgba32, 20, 20, 0.5)]
     [WithBasicTestPatternImages(250, 350, PixelTypes.Rgba32, 40, 60, 0.2)]
     public void Clip<TPixel>(TestImageProvider<TPixel> provider, float dx, float dy, float sizeMult)

tests/ImageSharp.Drawing.Tests/Drawing/FillImageBrushTests.cs

@@ -1,6 +1,8 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
+using System.Drawing;
+using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Drawing.Processing;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing;
@@ -72,11 +74,81 @@ public void CanDrawPortraitImage<TPixel>(TestImageProvider<TPixel> provider)
 
         overlay.Mutate(c => c.Crop(new Rectangle(0, 0, 90, 125)));
 
-        ImageBrush brush = new(overlay);
+        var brush = new ImageBrush(overlay);
+        background.Mutate(c => c.Fill(brush));
+
+        background.DebugSave(provider, appendSourceFileOrDescription: false);
+        background.CompareToReferenceOutput(provider, appendSourceFileOrDescription: false);
+    }
+
+    [Theory]
+    [WithTestPatternImage(400, 400, PixelTypes.Rgba32)]
+    public void CanOffsetImage<TPixel>(TestImageProvider<TPixel> provider)
+        where TPixel : unmanaged, IPixel<TPixel>
+    {
+        byte[] data = TestFile.Create(TestImages.Png.Ducky).Bytes;
+        using Image<TPixel> background = provider.GetImage();
+        using Image overlay = Image.Load<Rgba32>(data);
+
+        var brush = new ImageBrush(overlay);
+        background.Mutate(c => c.Fill(brush, new RectangularPolygon(0, 0, 400, 200)));
+        background.Mutate(c => c.Fill(brush, new RectangularPolygon(-100, 200, 500, 200)));
+
+        background.DebugSave(provider, appendSourceFileOrDescription: false);
+        background.CompareToReferenceOutput(provider, appendSourceFileOrDescription: false);
+    }
+
+    [Theory]
+    [WithTestPatternImage(400, 400, PixelTypes.Rgba32)]
+    public void CanOffsetViaBrushImage<TPixel>(TestImageProvider<TPixel> provider)
+        where TPixel : unmanaged, IPixel<TPixel>
+    {
+        byte[] data = TestFile.Create(TestImages.Png.Ducky).Bytes;
+        using Image<TPixel> background = provider.GetImage();
+        using Image overlay = Image.Load<Rgba32>(data);
+
+        var brush = new ImageBrush(overlay);
+        var brushOffset = new ImageBrush(overlay, new Point(100, 0));
+        background.Mutate(c => c.Fill(brush, new RectangularPolygon(0, 0, 400, 200)));
+        background.Mutate(c => c.Fill(brushOffset, new RectangularPolygon(0, 200, 400, 200)));
+
+        background.DebugSave(provider, appendSourceFileOrDescription: false);
+        background.CompareToReferenceOutput(provider, appendSourceFileOrDescription: false);
+    }
+
+    [Theory]
+    [WithSolidFilledImages(1000, 1000, "White", PixelTypes.Rgba32)]
+    public void CanDrawOffsetImage<TPixel>(TestImageProvider<TPixel> provider)
+    where TPixel : unmanaged, IPixel<TPixel>
+    {
+        byte[] data = TestFile.Create(TestImages.Png.Ducky).Bytes;
+        using Image<TPixel> background = provider.GetImage();
+
+        using Image templateImage = Image.Load<Rgba32>(data);
+        using Image finalTexture = BuildMultiRowTexture(templateImage);
+
+        finalTexture.Mutate(c => c.Resize(100, 200));
+
+        ImageBrush brush = new(finalTexture);
         background.Mutate(c => c.Fill(brush));
 
         background.DebugSave(provider, appendSourceFileOrDescription: false);
         background.CompareToReferenceOutput(provider, appendSourceFileOrDescription: false);
+
+        Image BuildMultiRowTexture(Image sourceTexture)
+        {
+            int halfWidth = sourceTexture.Width / 2;
+
+            Image final = sourceTexture.Clone(x => x.Resize(new ResizeOptions
+            {
+                Size = new Size(templateImage.Width, templateImage.Height * 2),
+                Position = AnchorPositionMode.TopLeft,
+                Mode = ResizeMode.Pad,
+            })
+            .DrawImage(templateImage, new Point(halfWidth, sourceTexture.Height), new Rectangle(0, 0, halfWidth, sourceTexture.Height), 1)
+            .DrawImage(templateImage, new Point(0, templateImage.Height), new Rectangle(halfWidth, 0, halfWidth, sourceTexture.Height), 1));
+            return final;
+        }
     }
 
     [Theory]