Sync 3.1 DrawImage fixes (#2612)

* Handle dedup of local palette of 256 length

* handle when foreground overhangs bottom of background

* prevent potential overflow

* reduce to a single par of clamping operations

* correctly calculate Rect when negative target set

---------

Co-authored-by: James Jackson-South <james_south@hotmail.com>

src/ImageSharp/Processing/Processors/Drawing/DrawImageProcessor{TPixelBg,TPixelFg}.cs

@@ -87,15 +87,21 @@ protected override void OnFrameApply(ImageFrame<TPixelBg> source)
         if (this.BackgroundLocation.X < 0)
         {
             foregroundRectangle.Width += this.BackgroundLocation.X;
+            foregroundRectangle.X -= this.BackgroundLocation.X;
             left = 0;
         }
 
         if (this.BackgroundLocation.Y < 0)
         {
             foregroundRectangle.Height += this.BackgroundLocation.Y;
+            foregroundRectangle.Y -= this.BackgroundLocation.Y;
             top = 0;
         }
 
+        // clamp the height/width to the availible space left to prevent overflowing
+        foregroundRectangle.Width = Math.Min(source.Width - left, foregroundRectangle.Width);
+        foregroundRectangle.Height = Math.Min(source.Height - top, foregroundRectangle.Height);
+
         int width = foregroundRectangle.Width;
         int height = foregroundRectangle.Height;
         if (width <= 0 || height <= 0)

tests/ImageSharp.Tests/Drawing/DrawImageTests.cs

@@ -251,4 +251,46 @@ public void Issue2447_C<TPixel>(TestImageProvider<TPixel> provider)
             appendPixelTypeToFileName: false,
             appendSourceFileOrDescription: false);
     }
+
+    [Theory]
+    [WithFile(TestImages.Png.Issue2447, PixelTypes.Rgba32)]
+    public void Issue2608_NegOffset<TPixel>(TestImageProvider<TPixel> provider)
+    where TPixel : unmanaged, IPixel<TPixel>
+    {
+        using Image<TPixel> foreground = provider.GetImage();
+        using Image<Rgba32> background = new(100, 100, new Rgba32(0, 255, 255));
+
+        background.Mutate(c => c.DrawImage(foreground, new Point(-10, -10), new Rectangle(32, 32, 32, 32), 1F));
+
+        background.DebugSave(
+            provider,
+            appendPixelTypeToFileName: false,
+            appendSourceFileOrDescription: false);
+
+        background.CompareToReferenceOutput(
+            provider,
+            appendPixelTypeToFileName: false,
+            appendSourceFileOrDescription: false);
+    }
+
+    [Theory]
+    [WithFile(TestImages.Png.Issue2447, PixelTypes.Rgba32)]
+    public void Issue2603<TPixel>(TestImageProvider<TPixel> provider)
+    where TPixel : unmanaged, IPixel<TPixel>
+    {
+        using Image<TPixel> foreground = provider.GetImage();
+        using Image<Rgba32> background = new(100, 100, new Rgba32(0, 255, 255));
+
+        background.Mutate(c => c.DrawImage(foreground, new Point(80, 80), new Rectangle(32, 32, 32, 32), 1F));
+
+        background.DebugSave(
+            provider,
+            appendPixelTypeToFileName: false,
+            appendSourceFileOrDescription: false);
+
+        background.CompareToReferenceOutput(
+            provider,
+            appendPixelTypeToFileName: false,
+            appendSourceFileOrDescription: false);
+    }
 }