Fix empty automation bounds for custom root providers (#21730)

* Add AutomationPeer.ToScreen so each peer converts its own bounding rectangle to screen coordinates, fixing empty UIA bounds for root providers that are not ControlAutomationPeers.

* Update AutomationPeer.cs

* Update AutomationPeer.cs

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

@@ -420,6 +420,17 @@ namespace Avalonia.Automation.Peers
         [PrivateApi]
         public AutomationPeer? GetAutomationRoot() => GetAutomationRootCore();
 
+        /// <summary>
+        /// Converts a rectangle in the peer's coordinate space, as returned by
+        /// <see cref="GetBoundingRectangle"/>, to screen coordinates; returns null if the peer is
+        /// not currently hosted in a rendered visual tree.
+        /// </summary>
+        /// <param name="rect">
+        /// A rectangle in the peer's own coordinate space, as returned by
+        /// <see cref="GetBoundingRectangle"/>.
+        /// </param>
+        public Rect? ToScreen(Rect rect) => ToScreenCore(rect);
+
         /// <summary>
         /// Gets a value that indicates whether the element that is associated with this automation
         /// peer currently has keyboard focus.
@@ -669,6 +680,8 @@ namespace Avalonia.Automation.Peers
 
         private protected virtual AutomationPeer? GetVisualRootCore() => GetAutomationRootCore();
 
+        private protected virtual Rect? ToScreenCore(Rect rect) => null;
+
 
         protected virtual bool IsContentElementOverrideCore()
         {

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

@@ -155,6 +155,13 @@ namespace Avalonia.Automation.Peers
             return null;
         }
 
+        private protected override Rect? ToScreenCore(Rect rect)
+        {
+            if (Owner?.PresentationSource?.RootVisual is not { } root)
+                return null;
+            return new PixelRect(root.PointToScreen(rect.TopLeft), root.PointToScreen(rect.BottomRight)).ToRect(1);
+        }
+
         /// <summary>
         /// Invalidates the peer's children and causes a re-read from <see cref="GetChildrenCore"/>.
         /// </summary>

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

@@ -11,7 +11,6 @@ using Avalonia.Automation;
 using Avalonia.Automation.Peers;
 using Avalonia.Controls.Automation.Peers;
 using Avalonia.Threading;
-using Avalonia.VisualTree;
 using Avalonia.Win32.Automation.Interop;
 using AAP = Avalonia.Automation.Provider;
 using UIA = Avalonia.Win32.Automation.Interop;
@@ -76,18 +75,7 @@ namespace Avalonia.Win32.Automation
 
         public virtual Rect GetBoundingRectangle()
         {
-            return InvokeSync(() =>
-            {
-                if (Peer.GetVisualRoot() is ControlAutomationPeer root &&
-                    root.Owner.GetPresentationSource() is not null)
-                {
-                    var originalRect = Peer.GetBoundingRectangle();
-                    return new PixelRect(root.Owner.PointToScreen(originalRect.TopLeft),
-                        root.Owner.PointToScreen(originalRect.BottomRight)).ToRect(1);
-                }
-
-                return default;
-            });
+            return InvokeSync(() => Peer.ToScreen(Peer.GetBoundingRectangle()) ?? default);
         }
 
         public virtual IRawElementProviderFragmentRoot? GetFragmentRoot()

tests/Avalonia.Controls.UnitTests/Automation/ControlAutomationPeerTests.cs

@@ -232,6 +232,31 @@ namespace Avalonia.Controls.UnitTests.Automation
             }
         }
 
+        public class ToScreen : ScopedTestBase
+        {
+            [Fact]
+            public void Converts_Rect_When_Attached_To_Rooted_Tree()
+            {
+                var border = new Border();
+                var root = new TestRoot(border);
+                var peer = CreatePeer(border);
+
+                Assert.Equal(new Rect(10, 20, 30, 40), peer.ToScreen(new Rect(10, 20, 30, 40)));
+            }
+
+            [Fact]
+            public void Returns_Null_When_Detached()
+            {
+                var border = new Border();
+                var root = new TestRoot(border);
+                var peer = CreatePeer(border);
+
+                root.Child = null;
+
+                Assert.Null(peer.ToScreen(new Rect(10, 20, 30, 40)));
+            }
+        }
+
         private static AutomationPeer CreatePeer(Control control)
         {
             return ControlAutomationPeer.CreatePeerForElement(control);