feat: Support CompositionStretch and [Horizontal|Vertical]AlignmentRa…

…tio and use that for ImageBrush

src/Uno.Foundation/SizeExtensions.cs

@@ -0,0 +1,80 @@
+namespace Windows.Foundation;
+
+internal static class SizeExtensions
+{
+	internal static double AspectRatio(this Size size)
+	{
+		var w = size.Width;
+		var h = size.Height;
+		switch (w)
+		{
+			case double.NegativeInfinity:
+				return -1;
+			case double.PositiveInfinity:
+				return 1;
+			case double.NaN:
+				return 1;
+			case 0.0d:
+				return 1;
+		}
+		switch (h)
+		{
+			case double.NegativeInfinity:
+				return -1;
+			case double.PositiveInfinity:
+				return 1;
+			case double.NaN:
+				return 1;
+			case 0.0d:
+				return 1; // special case
+			case 1.0d:
+				return w;
+		}
+		return w / h;
+	}
+
+#if __IOS__ || __MACOS__
+	internal static double AspectRatio(this CoreGraphics.CGSize size)
+	{
+		var w = size.Width;
+		var h = size.Height;
+		if (w == nfloat.NegativeInfinity)
+		{
+			return -1;
+		}
+		else if (w == nfloat.PositiveInfinity)
+		{
+			return 1;
+		}
+		else if (w == nfloat.NaN)
+		{
+			return 1;
+		}
+		else if (w == 0.0d)
+		{
+			return 1;
+		}
+		if (h == nfloat.NegativeInfinity)
+		{
+			return -1;
+		}
+		else if (h == nfloat.PositiveInfinity)
+		{
+			return 1;
+		}
+		else if (h == nfloat.NaN)
+		{
+			return 1;
+		}
+		else if (h == 0.0d)
+		{
+			return 1; // special case
+		}
+		else if (h == 1.0d)
+		{
+			return w;
+		}
+		return w / h;
+	}
+#endif
+}

src/Uno.UI.Composition/Composition/CompositionSurfaceBrush.skia.cs

@@ -4,12 +4,14 @@
 using System.Numerics;
 using Uno.UI.Composition;
 using SkiaSharp;
+using Windows.Foundation;
+using System.Diagnostics.CodeAnalysis;
 
 namespace Windows.UI.Composition
 {
 	public partial class CompositionSurfaceBrush : CompositionBrush, IOnlineBrush, ISizedBrush
 	{
-		bool IOnlineBrush.IsOnline => Surface is ISkiaSurface skiaSurface;
+		bool IOnlineBrush.IsOnline => Surface is ISkiaSurface;
 
 		bool ISizedBrush.IsSized => true;
 
@@ -24,19 +26,66 @@ public partial class CompositionSurfaceBrush : CompositionBrush, IOnlineBrush, I
 			};
 		}
 
-		internal override void UpdatePaint(SKPaint fillPaint, SKRect bounds)
+		private Rect GetArrangedImageRect(Size sourceSize, SKRect targetRect)
 		{
-			if (Surface is SkiaCompositionSurface scs)
-			{
-				var imageShader = SKShader.CreateImage(scs.Image, SKShaderTileMode.Repeat, SKShaderTileMode.Repeat, TransformMatrix.ToSKMatrix());
+			var size = GetArrangedImageSize(sourceSize, targetRect.Size.ToSize());
 
-				fillPaint.Shader = imageShader;
+			var point = new Point(targetRect.Left, targetRect.Top);
+			point.X += (targetRect.Width - size.Width) * HorizontalAlignmentRatio;
+			point.Y += (targetRect.Height - size.Height) * VerticalAlignmentRatio;
+			return new Rect(point, size);
+		}
 
-				fillPaint.IsAntialias = true;
+		private Size GetArrangedImageSize(Size sourceSize, Size targetSize)
+		{
+			var sourceAspectRatio = sourceSize.AspectRatio();
+			var targetAspectRatio = targetSize.AspectRatio();
+			switch (Stretch)
+			{
+				default:
+				case CompositionStretch.None:
+					return sourceSize;
+				case CompositionStretch.Fill:
+					return targetSize;
+				case CompositionStretch.Uniform:
+					return targetAspectRatio > sourceAspectRatio
+						? new Size(sourceSize.Width * targetSize.Height / sourceSize.Height, targetSize.Height)
+						: new Size(targetSize.Width, sourceSize.Height * targetSize.Width / sourceSize.Width);
+				case CompositionStretch.UniformToFill:
+					return targetAspectRatio < sourceAspectRatio
+						? new Size(sourceSize.Width * targetSize.Height / sourceSize.Height, targetSize.Height)
+						: new Size(targetSize.Width, sourceSize.Height * targetSize.Width / sourceSize.Width);
+			}
+		}
+
+		private static bool TryGetSkiaCompositionSurface(ICompositionSurface? surface, [NotNullWhen(true)] out SkiaCompositionSurface? skiaCompositionSurface)
+		{
+			if (surface is SkiaCompositionSurface scs)
+			{
+				skiaCompositionSurface = scs;
+				return true;
 			}
-			else if (Surface is ISkiaCompositionSurfaceProvider scsp && scsp.SkiaCompositionSurface is SkiaCompositionSurface scsps)
+			else if (surface is ISkiaCompositionSurfaceProvider scsp && scsp.SkiaCompositionSurface is SkiaCompositionSurface scsps)
+			{
+				skiaCompositionSurface = scsps;
+				return true;
+			}
+
+			skiaCompositionSurface = null;
+			return false;
+		}
+
+		internal override void UpdatePaint(SKPaint fillPaint, SKRect bounds)
+		{
+			if (TryGetSkiaCompositionSurface(Surface, out var scs))
 			{
-				var imageShader = SKShader.CreateImage(scsps.Image, SKShaderTileMode.Repeat, SKShaderTileMode.Repeat, TransformMatrix.ToSKMatrix());
+				var sourceImageSize = new Size(scs.Image!.Width, scs.Image.Height);
+				var backgroundArea = GetArrangedImageRect(sourceImageSize, bounds);
+				var matrix = Matrix3x2.CreateScale((float)(backgroundArea.Width / sourceImageSize.Width), (float)(backgroundArea.Height / sourceImageSize.Height));
+				matrix *= Matrix3x2.CreateTranslation((float)backgroundArea.Left, (float)backgroundArea.Top);
+				matrix *= TransformMatrix;
+
+				var imageShader = SKShader.CreateImage(scs.Image, SKShaderTileMode.Decal, SKShaderTileMode.Decal, matrix.ToSKMatrix());
 
 				fillPaint.Shader = imageShader;
 

src/Uno.UI/UI/LayoutHelper.cs

@@ -403,90 +403,6 @@ internal static bool IsEnclosedBy(this Rect enclosee, Rect encloser)
 		[Pure]
 		internal static double AspectRatio(this Rect rect) => rect.Size.AspectRatio();
 
-		[Pure]
-		internal static double AspectRatio(this Size size)
-		{
-			var w = size.Width;
-			var h = size.Height;
-
-			switch (w)
-			{
-				case NegativeInfinity:
-					return -1;
-				case PositiveInfinity:
-					return 1;
-				case NaN:
-					return 1;
-				case 0.0d:
-					return 1;
-			}
-
-			switch (h)
-			{
-				case NegativeInfinity:
-					return -1;
-				case PositiveInfinity:
-					return 1;
-				case NaN:
-					return 1;
-				case 0.0d:
-					return 1; // special case
-				case 1.0d:
-					return w;
-			}
-
-			return w / h;
-		}
-
-#if __IOS__ || __MACOS__
-		[Pure]
-		internal static double AspectRatio(this CoreGraphics.CGSize size)
-		{
-			var w = size.Width;
-			var h = size.Height;
-
-			if (w == nfloat.NegativeInfinity)
-			{
-				return -1;
-			}
-			else if (w == nfloat.PositiveInfinity)
-			{
-				return 1;
-			}
-			else if (w == nfloat.NaN)
-			{
-				return 1;
-			}
-			else if (w == 0.0d)
-			{
-				return 1;
-			}
-
-			if (h == nfloat.NegativeInfinity)
-			{
-				return -1;
-			}
-			else if (h == nfloat.PositiveInfinity)
-			{
-				return 1;
-			}
-			else if (h == nfloat.NaN)
-			{
-				return 1;
-			}
-			else if (h == 0.0d)
-			{
-				return 1; // special case
-			}
-			else if (h == 1.0d)
-			{
-				return w;
-			}
-
-			return w / h;
-		}
-#endif
-
 		[Pure]
 		internal static Rect GetBoundsRectRelativeTo(this FrameworkElement element, FrameworkElement relativeTo)
 		{

src/Uno.UI/UI/Xaml/Media/Brush.skia.cs

@@ -148,6 +148,9 @@ private static IDisposable AsssignAndObserveImageBrush(ImageBrush brush, Composi
 			{
 				if (brush.ImageDataCache is { } data)
 				{
+					surfaceBrush.Stretch = (CompositionStretch)brush.Stretch;
+					surfaceBrush.HorizontalAlignmentRatio = GetHorizontalAlignmentRatio(brush.AlignmentX);
+					surfaceBrush.VerticalAlignmentRatio = GetVerticalAlignmentRatio(brush.AlignmentY);
 					surfaceBrush.Surface = data.CompositionSurface;
 				}
 			};
@@ -158,6 +161,28 @@ private static IDisposable AsssignAndObserveImageBrush(ImageBrush brush, Composi
 			return new DisposableAction(() => brush.InvalidateRender -= onInvalidateRender);
 		}
 
+		private static float GetHorizontalAlignmentRatio(AlignmentX alignmentX)
+		{
+			return alignmentX switch
+			{
+				AlignmentX.Left => 0.0f,
+				AlignmentX.Center => 0.5f,
+				AlignmentX.Right => 1.0f,
+				_ => 0.5f, // this should never happen.
+			};
+		}
+
+		private static float GetVerticalAlignmentRatio(AlignmentY alignmentY)
+		{
+			return alignmentY switch
+			{
+				AlignmentY.Top => 0.0f,
+				AlignmentY.Center => 0.5f,
+				AlignmentY.Bottom => 1.0f,
+				_ => 0.5f, // this should never happen.
+			};
+		}
+
 		private static IDisposable AssignAndObserveRadialGradientBrush(RadialGradientBrush brush, Compositor compositor, BrushSetterHandler brushSetter)
 		{
 			var disposables = new CompositeDisposable();