Allow for disabling clipping of adorners. Cleanup AdornerLayer class.

src/Avalonia.Controls/Primitives/AdornerLayer.cs

@@ -1,19 +1,33 @@
 using System;
 using System.Collections.Specialized;
-using System.Linq;
-using System.Resources;
 using Avalonia.Media;
 using Avalonia.Rendering;
-using Avalonia.Utilities;
 using Avalonia.VisualTree;
 
+#nullable enable
+
 namespace Avalonia.Controls.Primitives
 {
-    // TODO: Need to track position of adorned elements and move the adorner if they move.
+    /// <summary>
+    /// Represents a surface for showing adorners.
+    /// Adorners are always on top of the adorned element and are positioned to stay relative to the adorned element.
+    /// </summary>
+    /// <remarks>
+    /// TODO: Need to track position of adorned elements and move the adorner if they move.
+    /// </remarks>
     public class AdornerLayer : Canvas, ICustomSimpleHitTest
     {
-        public static readonly AttachedProperty<Visual> AdornedElementProperty =
-            AvaloniaProperty.RegisterAttached<AdornerLayer, Visual, Visual>("AdornedElement");
+        /// <summary>
+        /// Allows for getting and setting of the adorned element.
+        /// </summary>
+        public static readonly AttachedProperty<Visual?> AdornedElementProperty =
+            AvaloniaProperty.RegisterAttached<AdornerLayer, Visual, Visual?>("AdornedElement");
+
+        /// <summary>
+        /// Allows for controlling clipping of the adorner.
+        /// </summary>
+        public static readonly AttachedProperty<bool> IsClipEnabledProperty =
+            AvaloniaProperty.RegisterAttached<AdornerLayer, Visual, bool>("IsClipEnabled", true);
 
         private static readonly AttachedProperty<AdornedElementInfo> s_adornedElementInfoProperty =
             AvaloniaProperty.RegisterAttached<AdornerLayer, Visual, AdornedElementInfo>("AdornedElementInfo");
@@ -28,7 +42,7 @@ public AdornerLayer()
             Children.CollectionChanged += ChildrenCollectionChanged;
         }
 
-        public static Visual GetAdornedElement(Visual adorner)
+        public static Visual? GetAdornedElement(Visual adorner)
         {
             return adorner.GetValue(AdornedElementProperty);
         }
@@ -38,12 +52,19 @@ public static void SetAdornedElement(Visual adorner, Visual adorned)
             adorner.SetValue(AdornedElementProperty, adorned);
         }
 
-        public static AdornerLayer GetAdornerLayer(IVisual visual)
+        public static AdornerLayer? GetAdornerLayer(IVisual visual)
+        {
+            return visual.FindAncestorOfType<VisualLayerManager>()?.AdornerLayer;
+        }
+
+        public static bool GetIsClipEnabled(Visual adorner)
         {
-            return visual.GetVisualAncestors()
-                .OfType<VisualLayerManager>()
-                .FirstOrDefault()
-                ?.AdornerLayer;
+            return adorner.GetValue(IsClipEnabledProperty);
+        }
+
+        public static void SetIsClipEnabled(Visual adorner, bool isClipEnabled)
+        {
+            adorner.SetValue(IsClipEnabledProperty, isClipEnabled);
         }
 
         protected override Size MeasureOverride(Size availableSize)
@@ -70,12 +91,13 @@ protected override Size ArrangeOverride(Size finalSize)
             foreach (var child in Children)
             {
                 var info = child.GetValue(s_adornedElementInfoProperty);
+                var isClipEnabled = child.GetValue(IsClipEnabledProperty);
 
                 if (info != null && info.Bounds.HasValue)
                 {
                     child.RenderTransform = new MatrixTransform(info.Bounds.Value.Transform);
                     child.RenderTransformOrigin = new RelativePoint(new Point(0,0), RelativeUnit.Absolute);
-                    UpdateClip(child, info.Bounds.Value);
+                    UpdateClip(child, info.Bounds.Value, isClipEnabled);
                     child.Arrange(info.Bounds.Value.Bounds);
                 }
                 else
@@ -87,16 +109,23 @@ protected override Size ArrangeOverride(Size finalSize)
             return finalSize;
         }
 
-        private static void AdornedElementChanged(AvaloniaPropertyChangedEventArgs e)
+        private static void AdornedElementChanged(AvaloniaPropertyChangedEventArgs<Visual?> e)
         {
             var adorner = (Visual)e.Sender;
-            var adorned = (Visual)e.NewValue;
+            var adorned = e.NewValue.GetValueOrDefault();
             var layer = adorner.GetVisualParent<AdornerLayer>();
             layer?.UpdateAdornedElement(adorner, adorned);
         }
 
-        private void UpdateClip(IControl control, TransformedBounds bounds)
+        private void UpdateClip(IControl control, TransformedBounds bounds, bool isEnabled)
         {
+            if (!isEnabled)
+            {
+                control.Clip = null;
+
+                return;
+            }
+
             if (!(control.Clip is RectangleGeometry clip))
             {
                 clip = new RectangleGeometry();
@@ -129,13 +158,13 @@ private void ChildrenCollectionChanged(object sender, NotifyCollectionChangedEve
             InvalidateArrange();
         }
 
-        private void UpdateAdornedElement(Visual adorner, Visual adorned)
+        private void UpdateAdornedElement(Visual adorner, Visual? adorned)
         {
             var info = adorner.GetValue(s_adornedElementInfoProperty);
 
             if (info != null)
             {
-                info.Subscription.Dispose();
+                info.Subscription!.Dispose();
 
                 if (adorned == null)
                 {
@@ -163,7 +192,7 @@ private void UpdateAdornedElement(Visual adorner, Visual adorned)
 
         private class AdornedElementInfo
         {
-            public IDisposable Subscription { get; set; }
+            public IDisposable? Subscription { get; set; }
 
             public TransformedBounds? Bounds { get; set; }
         }