fix(skia): make UIElement.HitTest strictly stronger than UIElement.Is…

…ViewHit

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

@@ -56,8 +56,8 @@ internal override void Paint(in PaintingSession session)
 		return shape;
 	}
 
-	/// <remarks>This does NOT take the clipping into account.</remarks>
-	internal virtual bool HitTest(Point point)
+	/// <inheritdoc />
+	internal override bool HitTest(Point point)
 	{
 		if (_shapes is null)
 		{

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

@@ -5,6 +5,7 @@
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Numerics;
+using Windows.Foundation;
 using SkiaSharp;
 using Uno.Extensions;
 using Uno.UI.Composition;
@@ -344,6 +345,9 @@ private PaintingSession CreateLocalSession(in PaintingSession parentSession)
 		return session;
 	}
 
+	/// <remarks>This does NOT take the clipping into account.</remarks>
+	internal virtual bool HitTest(Point point) => false;
+
 	[Flags]
 	internal enum VisualFlags : byte
 	{

src/Uno.UI/Microsoft/UI/Xaml/Controls/ScrollPresenter/ScrollPresenter.Uno.cs

@@ -23,6 +23,8 @@ partial void InitializePartial()
 	private protected override ShapeVisual CreateElementVisual() => Compositor.GetSharedCompositor().CreateBorderVisual();
 #endif
 
+	internal override bool IsViewHit() => ((IBorderInfoProvider)this).IsViewHit();
+
 	Brush IBorderInfoProvider.Background => Background;
 
 	BackgroundSizing IBorderInfoProvider.BackgroundSizing => BackgroundSizing.InnerBorderEdge;

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

@@ -322,17 +322,7 @@ protected override void OnBackgroundChanged(DependencyPropertyChangedEventArgs e
 
 	internal override bool CanHaveChildren() => true;
 
-	internal override bool IsViewHit() => IsViewHitImpl(this);
-
-	internal static bool IsViewHitImpl(FrameworkElement element)
-	{
-		_Debug.Assert(element is Panel
-			|| element is Border
-			|| element is ContentPresenter
-		);
-
-		return element.Background != null;
-	}
+	internal override bool IsViewHit() => ((IBorderInfoProvider)this).IsViewHit();
 
 #if !UNO_HAS_BORDER_VISUAL
 	private void UpdateBorder() => BorderRenderer.Update();

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

@@ -41,4 +41,6 @@ internal partial interface IBorderInfoProvider
 #if UNO_HAS_BORDER_VISUAL
 	BorderVisual BorderVisual { get; }
 #endif
+
+	bool IsViewHit() => Background != null || BorderBrush != null;
 }

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

@@ -1383,7 +1383,7 @@ protected override Size MeasureOverride(Size size)
 
 	internal override bool CanHaveChildren() => true;
 
-	internal override bool IsViewHit() => Border.IsViewHitImpl(this);
+	internal override bool IsViewHit() => ((IBorderInfoProvider)this).IsViewHit();
 
 	/// <summary>
 	/// Registers the provided native element in the native shell

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

@@ -32,6 +32,8 @@ private void UpdateBorder()
 	}
 #endif
 
+	internal override bool IsViewHit() => ((IBorderInfoProvider)this).IsViewHit();
+
 	protected internal virtual void OnNavigatedFrom(NavigationEventArgs e) { }
 
 	protected internal virtual void OnNavigatedTo(NavigationEventArgs e) { }

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

@@ -259,7 +259,7 @@ private protected void OnBackgroundSizingChangedInnerPanel(DependencyPropertyCha
 #endif
 	}
 
-	internal override bool IsViewHit() => Border.IsViewHitImpl(this);
+	internal override bool IsViewHit() => ((IBorderInfoProvider)this).IsViewHit();
 
 #if !UNO_HAS_BORDER_VISUAL
 	private void UpdateBorder() => _borderRenderer.Update();

src/Uno.UI/UI/Xaml/Controls/Popup/PopupPanel.cs

@@ -296,4 +296,7 @@ internal override bool IsViewHit()
 
 		return Popup?.IsLightDismissEnabled ?? false;
 	}
+
+	// This shouldn't be needed, see the above comment in IsViewHit
+	internal override bool HitTest(Point point) => IsViewHit();
 }

src/Uno.UI/UI/Xaml/Controls/TextBlock/TextVisual.skia.cs

@@ -34,5 +34,7 @@ internal override void Paint(in PaintingSession session)
 				owner.Inlines.Draw(in session);
 			}
 		}
+
+		internal override bool HitTest(Point point) => new Rect(Offset.X, Offset.Y, Size.X, Size.Y).Contains(point);
 	}
 }

src/Uno.UI/UI/Xaml/Media/VisualTreeHelper.cs

@@ -501,12 +501,6 @@ internal static (UIElement? element, Branch? stale) SearchDownForTopMostElementA
 				clippingBounds = clippingBounds.IntersectWith(transformToElement.Transform(clip)) ?? default;
 			}
 			TRACE($"- clipping (absolute): {clippingBounds.ToDebugString()}");
-
-			// The region where the current element draws itself.
-			// Be aware that children might be out of this rendering bounds if no clipping defined.
-			// This is expressed in the window (absolute) coordinate space.
-			var renderingBounds = transformToElement.Transform(new Rect(new Point(), element.LayoutSlotWithMarginsAndAlignments.Size)).IntersectWith(clippingBounds) ?? Rect.Empty;
-			TRACE($"- rendering (absolute): {renderingBounds.ToDebugString()}");
 #else
 			// First compute the transformation between the element and its parent coordinate space
 			var matrix = Matrix3x2.Identity;
@@ -662,12 +656,18 @@ internal static (UIElement? element, Branch? stale) SearchDownForTopMostElementA
 			// We didn't find any child at the given position, validate that element can be touched,
 			// and the position is in actual bounds(which might be different than the clipping bounds)
 #if __SKIA__
-			if (element.HitTest(transformToElement.Inverse().Transform(testPosition)) && renderingBounds.Contains(testPosition))
+			if (element.HitTest(transformToElement.Inverse().Transform(testPosition)))
 #else
-
 			if (elementHitTestVisibility == HitTestability.Visible && renderingBounds.Contains(testPosition))
 #endif
 			{
+				// UIElement.HitTest should be a stronger condition than elementHitTestVisibility == HitTestability.Visible
+				// On WASM we match the native-element hit-testability (i.e. the `pointer-events` css property) to the
+				// HitTestVisibility of the corresponding managed element, so if we implement UIElement.HitTest for WASM
+				// in the future, this assertion makes sure that we're not regressing (e.g. imagine
+				// elementHitTestVisibility != Visible, but element.HitTest returns true).
+				global::System.Diagnostics.Debug.Assert(elementHitTestVisibility == HitTestability.Visible);
+
 				TRACE($"> LEAF! ({element.GetDebugName()} is the OriginalSource) | stale branch: {stale?.ToString() ?? "-- none --"}");
 				return (element, stale);
 			}