Merge pull request #2262 from AvaloniaUI/fixes/2260-image-sizing

Fix image sizing

src/Avalonia.Controls/Image.cs

@@ -99,5 +99,22 @@ namespace Avalonia.Controls
                 return new Size();
             }
         }
+
+        /// <inheritdoc/>
+        protected override Size ArrangeOverride(Size finalSize)
+        {
+            var source = Source;
+
+            if (source != null)
+            {
+                var sourceSize = new Size(source.PixelSize.Width, source.PixelSize.Height);
+                var result = Stretch.CalculateSize(finalSize, sourceSize);
+                return result;
+            }
+            else
+            {
+                return new Size();
+            }
+        }
     }
 }

tests/Avalonia.Controls.UnitTests/ImageTests.cs

@@ -61,5 +61,61 @@ namespace Avalonia.Controls.UnitTests
 
             Assert.Equal(new Size(50, 50), target.DesiredSize);
         }
+
+        [Fact]
+        public void Arrange_Should_Return_Correct_Size_For_No_Stretch()
+        {
+            var bitmap = Mock.Of<IBitmap>(x => x.PixelSize == new PixelSize(50, 100));
+            var target = new Image();
+            target.Stretch = Stretch.None;
+            target.Source = bitmap;
+
+            target.Measure(new Size(50, 50));
+            target.Arrange(new Rect(0, 0, 100, 400));
+
+            Assert.Equal(new Size(50, 100), target.Bounds.Size);
+        }
+
+        [Fact]
+        public void Arrange_Should_Return_Correct_Size_For_Fill_Stretch()
+        {
+            var bitmap = Mock.Of<IBitmap>(x => x.PixelSize == new PixelSize(50, 100));
+            var target = new Image();
+            target.Stretch = Stretch.Fill;
+            target.Source = bitmap;
+
+            target.Measure(new Size(50, 50));
+            target.Arrange(new Rect(0, 0, 25, 100));
+
+            Assert.Equal(new Size(25, 100), target.Bounds.Size);
+        }
+
+        [Fact]
+        public void Arrange_Should_Return_Correct_Size_For_Uniform_Stretch()
+        {
+            var bitmap = Mock.Of<IBitmap>(x => x.PixelSize == new PixelSize(50, 100));
+            var target = new Image();
+            target.Stretch = Stretch.Uniform;
+            target.Source = bitmap;
+
+            target.Measure(new Size(50, 50));
+            target.Arrange(new Rect(0, 0, 25, 100));
+
+            Assert.Equal(new Size(25, 50), target.Bounds.Size);
+        }
+
+        [Fact]
+        public void Arrange_Should_Return_Correct_Size_For_UniformToFill_Stretch()
+        {
+            var bitmap = Mock.Of<IBitmap>(x => x.PixelSize == new PixelSize(50, 100));
+            var target = new Image();
+            target.Stretch = Stretch.UniformToFill;
+            target.Source = bitmap;
+
+            target.Measure(new Size(50, 50));
+            target.Arrange(new Rect(0, 0, 25, 100));
+
+            Assert.Equal(new Size(25, 100), target.Bounds.Size);
+        }
     }
 }