fix: Fix corner radius handling on Wasm

src/SamplesApp/UITests.Shared/Windows_UI_Xaml_Controls/BorderTests/Border_CornerRadius_BorderThickness.xaml

@@ -133,7 +133,7 @@
 					Maximum="100"
 					x:Name="LeftBorderThicknessSlider"
 					Value="{x:Bind LeftBorderThickness, Mode=TwoWay}" />
-			<Slider Header="Left:"
+			<Slider Header="Top:"
 					Minimum="0"
 					Maximum="100"
 					x:Name="TopBorderThicknessSlider"

src/Uno.UI.RuntimeTests/Tests/Windows_UI_Xaml_Controls/Given_Border.cs

@@ -563,6 +563,96 @@ public async Task Border_CornerRadius_GradientBrush()
 			ImageAssert.HasColorAt(result, textBoxRect.CenterX, textBoxRect.CenterY, "#FF00FF00", tolerance: 10);
 		}
 
+		[TestMethod]
+		public async Task When_CornerRadius()
+		{
+			var case1A = new Border()
+			{
+				Width = 200,
+				Height = 100,
+				CornerRadius = new(200),
+				Background = new SolidColorBrush(Colors.Red),
+			};
+
+			var case1B = new Border()
+			{
+				Width = 200,
+				Height = 100,
+				CornerRadius = new(100),
+				Background = new SolidColorBrush(Colors.Red),
+			};
+
+			var case1Expected = new Ellipse()
+			{
+				Width = 200,
+				Height = 100,
+				Fill = new SolidColorBrush(Colors.Red),
+			};
+
+			var case2 = new Border()
+			{
+				Width = 200,
+				Height = 100,
+				CornerRadius = new(200, 0, 0, 0),
+				Background = new SolidColorBrush(Colors.Blue),
+			};
+
+			var case2Expected = new Grid()
+			{
+				Width = 200,
+				Height = 100,
+				Children =
+				{
+					new Ellipse()
+					{
+						Width = 400,
+						Height = 200,
+						Fill = new SolidColorBrush(Colors.Blue),
+					}
+				}
+			};
+
+			var stackPanel = new StackPanel()
+			{
+				Children =
+				{
+					case1A,
+					case1B,
+					case1Expected,
+					case2,
+					case2Expected,
+				}
+			};
+
+			WindowHelper.WindowContent = stackPanel;
+			await WindowHelper.WaitForLoaded(stackPanel);
+
+			var renderer1A = new RenderTargetBitmap();
+			await renderer1A.RenderAsync(case1A);
+			var bitmap1A = await RawBitmap.From(renderer1A, case1A);
+
+			var renderer1B = new RenderTargetBitmap();
+			await renderer1B.RenderAsync(case1B);
+			var bitmap1B = await RawBitmap.From(renderer1B, case1B);
+
+			var renderer1Expected = new RenderTargetBitmap();
+			await renderer1Expected.RenderAsync(case1Expected);
+			var bitmap1Expected = await RawBitmap.From(renderer1Expected, case1Expected);
+
+			await ImageAssert.AreSimilarAsync(bitmap1A, bitmap1Expected, imperceptibilityThreshold: 0.7);
+			await ImageAssert.AreSimilarAsync(bitmap1B, bitmap1Expected, imperceptibilityThreshold: 0.7);
+
+			var renderer2 = new RenderTargetBitmap();
+			await renderer2.RenderAsync(case2);
+			var bitmap2 = await RawBitmap.From(renderer2, case2);
+
+			var renderer2Expected = new RenderTargetBitmap();
+			await renderer2Expected.RenderAsync(case2Expected);
+			var bitmap2Expected = await RawBitmap.From(renderer2Expected, case2Expected);
+
+			await ImageAssert.AreSimilarAsync(bitmap2, bitmap2Expected, imperceptibilityThreshold: 0.7);
+		}
+
 		[TestMethod]
 		public async Task Border_AntiAlias()
 		{

src/Uno.UI.Toolkit/ElevatedView.cs

@@ -178,7 +178,7 @@ private void UpdateElevation()
 			{
 #if __WASM__
 				this.SetElevationInternal(Elevation, ShadowColor);
-				this.SetCornerRadius(CornerRadius);
+				this.SetBorder(BorderThickness, BorderBrush, CornerRadius);
 #elif __IOS__ || __MACOS__
 				this.SetElevationInternal(Elevation, ShadowColor, _border.BoundsPath);
 #elif __ANDROID__

src/Uno.UI/UI/Xaml/Controls/Border/Border.wasm.cs

@@ -1,19 +1,10 @@
-using System;
-using System.Collections.Generic;
-using System.Text;
-using Uno.Extensions;
-using System.Linq;
-using System.Drawing;
-using Uno.Disposables;
-using Windows.UI.Xaml.Media;
-using Uno.UI;
-
-namespace Windows.UI.Xaml.Controls
+namespace Windows.UI.Xaml.Controls
 {
 	public partial class Border
 	{
 		public Border()
 		{
+			this.SizeChanged += (_, _) => UpdateBorder();
 		}
 
 		partial void OnChildChangedPartial(UIElement previousValue, UIElement newValue)
@@ -28,7 +19,7 @@ partial void OnChildChangedPartial(UIElement previousValue, UIElement newValue)
 
 		private void UpdateBorder()
 		{
-			SetBorder(BorderThickness, BorderBrush);
+			SetBorder(BorderThickness, BorderBrush, CornerRadius);
 		}
 
 		private protected override void OnLoaded()
@@ -54,7 +45,7 @@ partial void OnPaddingChangedPartial(Thickness oldValue, Thickness newValue)
 
 		partial void OnCornerRadiusUpdatedPartial(CornerRadius oldValue, CornerRadius newValue)
 		{
-			SetCornerRadius(newValue);
+			UpdateBorder();
 		}
 
 		protected override void OnBackgroundChanged(DependencyPropertyChangedEventArgs e)

src/Uno.UI/UI/Xaml/Controls/Border/BorderLayerRenderer.wasm.cs

@@ -10,14 +10,14 @@
 using RadialGradientBrush = Microsoft.UI.Xaml.Media.RadialGradientBrush;
 using Uno;
 using Uno.UI.Helpers;
+using Uno.UI.Extensions;
 
 namespace Windows.UI.Xaml.Shapes
 {
 	partial class BorderLayerRenderer
 	{
 		private Brush _background;
-		private (Brush, Thickness) _border;
-		private CornerRadius _cornerRadius;
+		private (Brush, Thickness, CornerRadius) _border;
 
 		private Action _backgroundChanged;
 
@@ -38,35 +38,14 @@ public void UpdateLayer(
 				SetAndObserveBackgroundBrush(fwElt, oldValue, background, ref _backgroundChanged);
 			}
 
-			if (_border != (borderBrush, borderThickness))
+			if (_border != (borderBrush, borderThickness, cornerRadius))
 			{
-				_border = (borderBrush, borderThickness);
-				SetBorder(element, borderThickness, borderBrush);
-			}
-
-			if (_cornerRadius != cornerRadius)
-			{
-				_cornerRadius = cornerRadius;
-				SetCornerRadius(element, cornerRadius);
-			}
-		}
-
-		public static void SetCornerRadius(UIElement element, CornerRadius cornerRadius)
-		{
-			if (cornerRadius == CornerRadius.None)
-			{
-				element.ResetStyle("border-radius", "overflow");
-			}
-			else
-			{
-				var borderRadiusCssString = $"min(50%,{cornerRadius.TopLeft.ToStringInvariant()}px) min(50%,{cornerRadius.TopRight.ToStringInvariant()}px) min(50%,{cornerRadius.BottomRight.ToStringInvariant()}px) min(50%,{cornerRadius.BottomLeft.ToStringInvariant()}px)";
-				element.SetStyle(
-					("border-radius", borderRadiusCssString),
-					("overflow", "hidden")); // overflow: hidden is required here because the clipping can't do its job when it's non-rectangular.
+				_border = (borderBrush, borderThickness, cornerRadius);
+				SetBorder(element, borderThickness, borderBrush, cornerRadius);
 			}
 		}
 
-		public static void SetBorder(UIElement element, Thickness thickness, Brush brush)
+		public static void SetBorder(UIElement element, Thickness thickness, Brush brush, CornerRadius cornerRadius)
 		{
 			if (thickness == Thickness.Empty)
 			{
@@ -89,7 +68,7 @@ public static void SetBorder(UIElement element, Thickness thickness, Brush brush
 							("border-width", borderWidth));
 						break;
 					case GradientBrush gradientBrush:
-						var border = gradientBrush.ToCssString(element.RenderSize); // TODO: Reevaluate when size is changing
+						var border = gradientBrush.ToCssString(element.RenderSize);
 						element.SetStyle(
 							("border-style", "solid"),
 							("border-color", ""),
@@ -98,7 +77,7 @@ public static void SetBorder(UIElement element, Thickness thickness, Brush brush
 							("border-image-slice", "1"));
 						break;
 					case RadialGradientBrush radialGradientBrush:
-						var radialBorder = radialGradientBrush.ToCssString(element.RenderSize); // TODO: Reevaluate when size is changing
+						var radialBorder = radialGradientBrush.ToCssString(element.RenderSize);
 						element.SetStyle(
 							("border-style", "solid"),
 							("border-color", ""),
@@ -119,6 +98,16 @@ public static void SetBorder(UIElement element, Thickness thickness, Brush brush
 						break;
 				}
 			}
+
+			if (cornerRadius == CornerRadius.None)
+			{
+				element.ResetStyle("border-radius", "overflow");
+			}
+			else
+			{
+				var outer = cornerRadius.GetRadii(element.RenderSize, thickness).Outer;
+				WindowManagerInterop.SetCornerRadius(element.HtmlId, outer.TopLeft.X, outer.TopLeft.Y, outer.TopRight.X, outer.TopRight.Y, outer.BottomRight.X, outer.BottomRight.Y, outer.BottomLeft.X, outer.BottomLeft.Y);
+			}
 		}
 
 		public static void SetAndObserveBackgroundBrush(FrameworkElement element, Brush oldValue, Brush newValue, ref Action brushChanged)

src/Uno.UI/UI/Xaml/Controls/ContentPresenter/ContentPresenter.wasm.cs

@@ -20,6 +20,7 @@ public partial class ContentPresenter : FrameworkElement
 		public ContentPresenter()
 		{
 			InitializeContentPresenter();
+			this.SizeChanged += (_, _) => UpdateBorder();
 		}
 
 		private void SetUpdateTemplate()
@@ -39,12 +40,12 @@ partial void UnregisterContentTemplateRoot()
 
 		private void UpdateCornerRadius(CornerRadius radius)
 		{
-			SetCornerRadius(radius);
+			UpdateBorder();
 		}
 
 		private void UpdateBorder()
 		{
-			SetBorder(BorderThickness, BorderBrush);
+			SetBorder(BorderThickness, BorderBrush, CornerRadius);
 		}
 
 		private void ClearBorder()

src/Uno.UI/UI/Xaml/Controls/Page/Page.wasm.cs

@@ -16,7 +16,7 @@ private void InitializeBorder()
 
 		private void UpdateBorder()
 		{
-			SetBorder(Thickness.Empty, null);
+			SetBorder(Thickness.Empty, null, default);
 		}
 	}
 }

src/Uno.UI/UI/Xaml/Controls/Panel/Panel.wasm.cs

@@ -26,13 +26,14 @@ public partial class Panel : IEnumerable
 		public Panel()
 		{
 			Initialize();
+			this.SizeChanged += (_, _) => UpdateBorder();
 		}
 
 		partial void Initialize();
 
 		partial void UpdateBorder()
 		{
-			SetBorder(BorderThicknessInternal, BorderBrushInternal);
+			SetBorder(BorderThicknessInternal, BorderBrushInternal, CornerRadiusInternal);
 		}
 
 		protected virtual void OnChildrenChanged()
@@ -58,7 +59,7 @@ partial void OnBorderThicknessChangedPartial(Thickness oldValue, Thickness newVa
 
 		partial void OnCornerRadiusChangedPartial(CornerRadius oldValue, CornerRadius newValue)
 		{
-			SetCornerRadius(newValue);
+			UpdateBorder();
 		}
 
 		/// <summary>        

src/Uno.UI/UI/Xaml/FrameworkElement.wasm.cs

@@ -207,11 +207,8 @@ public event RoutedEventHandler Unloaded
 
 		public IEnumerator GetEnumerator() => _children.GetEnumerator();
 
-		protected void SetCornerRadius(CornerRadius cornerRadius)
-			=> BorderLayerRenderer.SetCornerRadius(this, cornerRadius);
-
-		protected void SetBorder(Thickness thickness, Brush brush)
-			=> BorderLayerRenderer.SetBorder(this, thickness, brush);
+		protected void SetBorder(Thickness thickness, Brush brush, CornerRadius cornerRadius)
+			=> BorderLayerRenderer.SetBorder(this, thickness, brush, cornerRadius);
 
 		partial void OnBackgroundSizingChangedPartial(DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs)
 		{

src/Uno.UI/UI/Xaml/WindowManagerInterop.wasm.cs

@@ -1042,6 +1042,10 @@
 
 		internal static void SetImageAsMonochrome(IntPtr htmlId, string url, string color)
 			=> NativeMethods.SetImageAsMonochrome(htmlId, url, color);
+
+		internal static void SetCornerRadius(IntPtr htmlId, float topLeftX, float topLeftY, float topRightX, float topRightY, float bottomRightX, float bottomRightY, float bottomLeftX, float bottomLeftY)
+			=> NativeMethods.SetCornerRadius(htmlId, topLeftX, topLeftY, topRightX, topRightY, bottomRightX, bottomRightY, bottomLeftX, bottomLeftY);
+
 		internal static void SetRootElement(IntPtr htmlId)
 		{
 			NativeMethods.SetRootElement(htmlId);
@@ -1144,6 +1148,9 @@
 			[JSImport("globalThis.Uno.UI.WindowManager.current.setImageAsMonochrome")]
 			internal static partial void SetImageAsMonochrome(IntPtr htmlId, string url, string color);
 
+			[JSImport("globalThis.Uno.UI.WindowManager.current.setCornerRadius")]
+			internal static partial void SetCornerRadius(IntPtr htmlId, float topLeftX, float topLeftY, float topRightX, float topRightY, float bottomRightX, float bottomRightY, float bottomLeftX, float bottomLeftY);
+
 			[JSImport("globalThis.Uno.UI.WindowManager.current.setPointerCapture")]
 			internal static partial void SetPointerCapture(IntPtr htmlId, double pointerId);
 

src/Uno.UI/ts/WindowManager.ts

@@ -1498,6 +1498,12 @@
 			}
 		}
 
+		public setCornerRadius(viewId: number, topLeftX: number, topLeftY: number, topRightX: number, topRightY: number, bottomRightX: number, bottomRightY: number, bottomLeftX: number, bottomLeftY: number) {
+			const element = this.getView(viewId);
+			element.style.borderRadius = `${topLeftX}px ${topRightX}px ${bottomRightX}px ${bottomLeftX}px / ${topLeftY}px ${topRightY}px ${bottomRightY}px ${bottomLeftY}px`;
+			element.style.overflow = "hidden"; // overflow: hidden is required here because the clipping can't do its job when it's non-rectangular.
+		}
+
 		public setPointerCapture(viewId: number, pointerId: number): void {
 			this.getView(viewId).setPointerCapture(pointerId);
 		}