Android: never walk an InteropAutomationPeer during accessibility traversal (AvaloniaUI#22123)

* Android: never walk an InteropAutomationPeer during accessibility traversal

InteropAutomationPeer - the peer of a native interop control - throws
NotImplementedException from almost every member (GetOrCreateChildrenCore,
GetNameCore, GetBoundingRectangleCore, IsEnabledCore...), because it is meant to
be special-cased by each platform backend. macOS does so through
AvnAutomationPeer.IsInteropPeer, Windows through AutomationNode.InteropAutomationNode.
Android did not, and AvaloniaAccessHelper called those members without any guard.

Any accessibility traversal reaching a screen that hosts a native control - a
NativeControlHost, so a WebView or an embedded media surface - therefore threw from
inside an accessibility callback, which is not recoverable: the process goes down.
It is reproducible in one command on such a screen:

    adb shell uiautomator dump

Reported by any accessibility client walking the tree, so a screen reader or an MDM
agent would take the same path.

Interop peers are now filtered at every point where a virtual view ID could be
handed out: the point hit test, the visible-views enumeration, the focused peer, and
the children walk. A virtual view ID is therefore never allocated for one, and
OnPopulateNodeForVirtualView never has to deal with one - which matters, because it
may not answer with an unpopulated node: ExploreByTouchHelper.createNodeForChild
rejects that and throws too.

Skipping is the correct behaviour here rather than merely the safe one: a native
control is a real Android View, already exposed to the accessibility framework on
its own. Presenting it a second time as an Avalonia virtual view would duplicate it.

InteropAutomationPeer is internal, hence the InternalsVisibleTo entry - Avalonia.Native
and Avalonia.Win32.Automation already have one for the same reason.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* Drop the explanatory comments, per review

The rationale belongs in the pull request, not in the source.

---------

Co-authored-by: ronnycohen <19652995+ronnycohen@users.noreply.github.com>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

Author: 2 people

src/Android/Avalonia.Android/AvaloniaAccessHelper.cs

@@ -8,6 +8,7 @@
 using Avalonia.Automation;
 using Avalonia.Automation.Peers;
 using Avalonia.Automation.Provider;
+using Avalonia.Controls.Automation.Peers;
 using Java.Lang;
 
 namespace Avalonia.Android
@@ -84,6 +85,8 @@ public AvaloniaAccessHelper(AvaloniaView view) : base(view)
             }
         }
 
+        private static bool IsInteropPeer(AutomationPeer peer) => peer is InteropAutomationPeer;
+
         private HashSet<INodeInfoProvider> GetOrCreateNodeInfoProvidersFromPeer(AutomationPeer peer, out int virtualViewId)
         {
             int peerViewId;
@@ -175,6 +178,11 @@ protected override int GetVirtualViewAt(float x, float y)
             AutomationPeer? peer = embeddedRootProvider?.GetPeerFromPoint(p);
             if (peer is not null)
             {
+                if (IsInteropPeer(peer))
+                {
+                    return InvalidId;
+                }
+
                 int virtualViewId;
                 if (peer.GetParent() is AutomationPeer parent && 
                     !s_containerTypes.Contains(parent.GetAutomationControlType()))
@@ -191,7 +199,7 @@ protected override int GetVirtualViewAt(float x, float y)
             else
             {
                 peer = embeddedRootProvider?.GetFocus();
-                return peer is null ? InvalidId : _peerIds[peer];
+                return peer is null || IsInteropPeer(peer) ? InvalidId : _peerIds[peer];
             }
         }
 
@@ -204,6 +212,11 @@ protected override void GetVisibleVirtualViews(IList<Integer>? virtualViewIds)
 
             foreach (AutomationPeer peer in _peers[0].GetChildren())
             {
+                if (IsInteropPeer(peer))
+                {
+                    continue;
+                }
+
                 GetOrCreateNodeInfoProvidersFromPeer(peer, out int virtualViewId);
                 virtualViewIds.Add(Integer.ValueOf(virtualViewId));
             }
@@ -255,6 +268,11 @@ protected override void OnPopulateNodeForVirtualView(int virtualViewId, Accessib
             // UI logical structure
             foreach (AutomationPeer child in peer.GetChildren())
             {
+                if (IsInteropPeer(child))
+                {
+                    continue;
+                }
+
                 GetOrCreateNodeInfoProvidersFromPeer(child, out int childId);
                 nodeInfo.AddChild(_view, childId);
             }

src/Avalonia.Controls/Avalonia.Controls.csproj

@@ -22,6 +22,7 @@
     <InternalsVisibleTo Include="AvaloniaUI.DiagnosticsSupport.Avalonia, PublicKey=$(AvaloniaPublicKey)" />
     <InternalsVisibleTo Include="Avalonia.LeakTests, PublicKey=$(AvaloniaPublicKey)" />
     <InternalsVisibleTo Include="Avalonia.Headless, PublicKey=$(AvaloniaPublicKey)" />
+    <InternalsVisibleTo Include="Avalonia.Android, PublicKey=$(AvaloniaPublicKey)" />
     <InternalsVisibleTo Include="Avalonia.Native, PublicKey=$(AvaloniaPublicKey)" />
     <InternalsVisibleTo Include="Avalonia.Win32, PublicKey=$(AvaloniaPublicKey)" />
     <InternalsVisibleTo Include="Avalonia.Win32.Automation, PublicKey=$(AvaloniaPublicKey)" />