Merge pull request #8847 from AvaloniaUI/fixes/compositing-renderer-hit-test

Filter-out child elements during hit-testing too

src/Avalonia.Base/Rendering/Composition/CompositingRenderer.cs

@@ -87,7 +87,16 @@ public class CompositingRenderer : IRendererWithCompositor
     /// <inheritdoc/>
     public IEnumerable<IVisual> HitTest(Point p, IVisual root, Func<IVisual, bool>? filter)
     {
-        var res = CompositionTarget.TryHitTest(p, filter);
+        Func<CompositionVisual, bool>? f = null;
+        if (filter != null)
+            f = v =>
+            {
+                if (v is CompositionDrawListVisual dlv)
+                    return filter(dlv.Visual);
+                return true;
+            };
+        
+        var res = CompositionTarget.TryHitTest(p, f);
         if(res == null)
             yield break;
         foreach(var v in res)

src/Avalonia.Base/Rendering/Composition/CompositionDrawListVisual.cs

@@ -54,13 +54,11 @@ internal class CompositionDrawListVisual : CompositionContainerVisual
         Visual = visual;
     }
 
-    internal override bool HitTest(Point pt, Func<IVisual, bool>? filter)
+    internal override bool HitTest(Point pt)
     {
         var custom = Visual as ICustomHitTest;
         if (DrawList == null && custom == null)
             return false;
-        if (filter != null && !filter(Visual))
-            return false;
         if (custom != null)
         {
             // Simulate the old behavior

src/Avalonia.Base/Rendering/Composition/CompositionTarget.cs

@@ -31,7 +31,7 @@ namespace Avalonia.Rendering.Composition
         /// <param name="point"></param>
         /// <param name="filter"></param>
         /// <returns></returns>
-        public PooledList<CompositionVisual>? TryHitTest(Point point, Func<IVisual, bool>? filter)
+        public PooledList<CompositionVisual>? TryHitTest(Point point, Func<CompositionVisual, bool>? filter)
         {
             Server.Readback.NextRead();
             if (Root == null)
@@ -88,10 +88,14 @@ namespace Avalonia.Rendering.Composition
         }
         
         void HitTestCore(CompositionVisual visual, Point globalPoint, PooledList<CompositionVisual> result,
-            Func<IVisual, bool>? filter)
+            Func<CompositionVisual, bool>? filter)
         {
             if (visual.Visible == false)
                 return;
+            
+            if (filter != null && !filter(visual))
+                return;
+            
             if (!TryTransformTo(visual, globalPoint, out var point))
                 return;
 
@@ -111,7 +115,7 @@ namespace Avalonia.Rendering.Composition
                 }
             
             // Hit-test the current node
-            if (visual.HitTest(point, filter)) 
+            if (visual.HitTest(point)) 
                 result.Add(visual);
         }
 

src/Avalonia.Base/Rendering/Composition/Visual.cs

@@ -53,6 +53,6 @@ namespace Avalonia.Rendering.Composition
         
         internal object? Tag { get; set; }
 
-        internal virtual bool HitTest(Point point, Func<IVisual, bool>? filter) => true;
+        internal virtual bool HitTest(Point point) => true;
     }
 }

tests/Avalonia.Base.UnitTests/Rendering/CompositorHitTestingTests.cs

@@ -432,6 +432,33 @@ public class CompositorHitTestingTests : CompositorTestsBase
             s.AssertHitTest(new Point(5, 10), null, targetRectangle);
         }
     }
+    
+    
+    [Fact]
+    public void HitTest_Filter_Should_Filter_Out_Children()
+    {
+        using (var s = new CompositorServices(new Size(200, 200)))
+        {
+            Border child, parent;
+            s.TopLevel.Content = parent = new Border
+            {
+                Width = 100,
+                Height = 100,
+                Background = Brushes.Red,
+                HorizontalAlignment = HorizontalAlignment.Center,
+                VerticalAlignment = VerticalAlignment.Center,
+                Child = child = new Border
+                {
+                    Background = Brushes.Red,
+                    HorizontalAlignment = HorizontalAlignment.Stretch,
+                    VerticalAlignment = VerticalAlignment.Stretch,
+                }
+            };
+
+            s.AssertHitTest(new Point(100, 100), null, child, parent);
+            s.AssertHitTest(new Point(100, 100), v => v != parent);
+        }
+    }
 
     private IDisposable TestApplication()
     {