handle when foreground overhangs bottom of background

Author: tocsoft

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

@@ -96,6 +96,20 @@ protected override void OnFrameApply(ImageFrame<TPixelBg> source)
             top = 0;
         }
 
+        if (left + foregroundRectangle.Width > source.Width)
+        {
+            // will overhange, lets trim it down
+            int diff = (left + foregroundRectangle.Width) - source.Width;
+            foregroundRectangle.Width -= diff;
+        }
+
+        if (top + foregroundRectangle.Height > source.Height)
+        {
+            // will overhange, lets trim it down
+            int diff = (top + foregroundRectangle.Height) - source.Height;
+            foregroundRectangle.Height -= diff;
+        }
+
         int width = foregroundRectangle.Width;
         int height = foregroundRectangle.Height;
         if (width <= 0 || height <= 0)

tests/ImageSharp.Tests/Drawing/DrawImageTests.cs

@@ -251,4 +251,25 @@ public void Issue2447_C<TPixel>(TestImageProvider<TPixel> 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);
+    }
 }