Fix Adorner Layer Clipping (#13921)

* Don't overwrite IsClipEnabled.

The user should be able to set this on an adorner themselves.

* Use correct clip bounds for adorners.

Only take the adorned visual's clip bounds into account if the adorner is clipped to these bounds.

* Disable clipping on GridSplitter adorner.

Fixes #10700

* Don't clip adorners in ControlCatalog.

Default setting is `true`, but this was being overridden in `AdornerLayer.AddVisualAdorner`. That was fixed by an earlier commit in this PR, so property needs to be set explicitly to false in ControlCatalog.

samples/ControlCatalog/Pages/AdornerLayerPage.xaml

@@ -50,7 +50,8 @@
                     Background="Cyan"
                     IsHitTestVisible="False"
                     Opacity="0.3"
-                    IsVisible="True">
+                    IsVisible="True"
+                    AdornerLayer.IsClipEnabled="False">
               <Line StartPoint="-10000,0" EndPoint="10000,0" Stroke="Cyan" StrokeThickness="1" />
               <Line StartPoint="-10000,42" EndPoint="10000,42" Stroke="Cyan" StrokeThickness="1" />
               <Line StartPoint="0,-10000" EndPoint="0,10000" Stroke="Cyan" StrokeThickness="1" />

src/Avalonia.Base/Rendering/Composition/Server/ServerCompositionVisual.cs

@@ -205,7 +205,7 @@ public virtual UpdateResult Update(ServerCompositionTarget root)
             }
 
             _combinedTransformedClipBounds =
-                AdornedVisual?._combinedTransformedClipBounds
+                (AdornerIsClipped ? AdornedVisual?._combinedTransformedClipBounds : null)
                 ?? (Parent?.Effect == null ? Parent?._combinedTransformedClipBounds : null)
                 ?? new Rect(Root!.Size);
 

src/Avalonia.Controls/GridSplitter.cs

@@ -341,6 +341,7 @@ private void SetupPreviewAdorner()
                 _resizeData.Adorner = new PreviewAdorner(builtPreviewContent);
 
                 AdornerLayer.SetAdornedElement(_resizeData.Adorner, this);
+                AdornerLayer.SetIsClipEnabled(_resizeData.Adorner, false);
 
                 adornerLayer.Children.Add(_resizeData.Adorner);
 

src/Avalonia.Controls/Primitives/AdornerLayer.cs

@@ -174,7 +174,6 @@ private static void AddVisualAdorner(Visual visual, Control? adorner, AdornerLay
             }
 
             SetAdornedElement(adorner, visual);
-            SetIsClipEnabled(adorner, false);
 
             ((ISetLogicalParent) adorner).SetParent(visual);
             layer.Children.Add(adorner);