Allow an AutomationPeer to override its visual root.

This is needed for example when a UI framework hosts a peer in the automation tree of a main window whose control is actually hosted in a popup. It allows the bounding rectangle to be calculated correctly in that case.

s

Author: grokys

src/Avalonia.Controls/Automation/Peers/AutomationPeer.cs

@@ -115,9 +115,14 @@ public abstract class AutomationPeer
         /// <summary>
         /// Gets the <see cref="AutomationPeer"/> that is the parent of this <see cref="AutomationPeer"/>.
         /// </summary>
-        /// <returns></returns>
         public AutomationPeer? GetParent() => GetParentCore();
 
+        /// <summary>
+        /// Gets the <see cref="AutomationPeer"/> that is the root of this <see cref="AutomationPeer"/>'s
+        /// visual tree.
+        /// </summary>
+        public AutomationPeer? GetVisualRoot() => GetVisualRootCore();
+
         /// <summary>
         /// Gets a value that indicates whether the element that is associated with this automation
         /// peer currently has keyboard focus.
@@ -247,6 +252,22 @@ protected virtual AutomationControlType GetControlTypeOverrideCore()
             return GetAutomationControlTypeCore();
         }
 
+        protected virtual AutomationPeer? GetVisualRootCore()
+        {
+            var parent = GetParent();
+
+            while (parent != null)
+            {
+                var nextParent = parent.GetParent();
+                if (nextParent == null)
+                    return parent;
+                parent = nextParent;
+            }
+
+            return null;
+        }
+
+
         protected virtual bool IsContentElementOverrideCore()
         {
             return IsControlElement() && IsContentElementCore();

src/Windows/Avalonia.Win32/Automation/AutomationNode.cs

@@ -75,7 +75,7 @@ public Rect BoundingRectangle
 
         public virtual IRawElementProviderFragmentRoot? FragmentRoot
         {
-            get => InvokeSync(() => GetRoot()) as IRawElementProviderFragmentRoot;
+            get => InvokeSync(() => GetRoot());
         }
 
         public virtual IRawElementProviderSimple? HostRawElementProvider => null;
@@ -243,20 +243,10 @@ protected void RaiseFocusChanged(AutomationNode? focused)
                 (int)UiaEventId.AutomationFocusChanged);
         }
 
-        private AutomationNode? GetRoot()
+        private RootAutomationNode? GetRoot()
         {
             Dispatcher.UIThread.VerifyAccess();
-
-            var peer = Peer;
-            var parent = peer.GetParent();
-
-            while (peer.GetProvider<AAP.IRootProvider>() is null && parent is object)
-            {
-                peer = parent;
-                parent = peer.GetParent();
-            }
-
-            return peer is object ? GetOrCreate(peer) : null;
+            return GetOrCreate(Peer.GetVisualRoot()) as RootAutomationNode;
         }
 
         private void OnPeerChildrenChanged(object? sender, EventArgs e)