Introduce PresentationSource, move some responsibilities from TopLevel

samples/ControlCatalog/MainView.xaml.cs

@@ -45,7 +45,7 @@ private void FlowDirection_SelectionChanged(object? sender, SelectionChangedEven
 
         private void Decorations_SelectionChanged(object? sender, SelectionChangedEventArgs e)
         {
-            if (VisualRoot is Window window && e.AddedItems.Count > 0 && e.AddedItems[0] is SystemDecorations systemDecorations)
+            if (TopLevel.GetTopLevel(this) is Window window && e.AddedItems.Count > 0 && e.AddedItems[0] is SystemDecorations systemDecorations)
             {
                 window.SystemDecorations = systemDecorations;
             }
@@ -78,7 +78,7 @@ protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
         {
             base.OnAttachedToVisualTree(e);
 
-            if (VisualRoot is Window window)
+            if (TopLevel.GetTopLevel(this) is Window window)
                 Decorations.SelectedIndex = (int)window.SystemDecorations;
 
             var insets = TopLevel.GetTopLevel(this)!.InsetsManager;

samples/ControlCatalog/ViewModels/ContextPageViewModel.cs

@@ -49,7 +49,7 @@ public ContextPageViewModel()
 
         public async Task Open()
         {
-            var window = View?.GetVisualRoot() as Window;
+            var window = TopLevel.GetTopLevel(View) as Window;
             if (window == null)
                 return;
 

samples/ControlCatalog/ViewModels/MenuPageViewModel.cs

@@ -69,7 +69,7 @@ public MenuPageViewModel()
 
         public async Task Open()
         {
-            var window = View?.GetVisualRoot() as Window;
+            var window = TopLevel.GetTopLevel(View) as Window;
             if (window == null)
                 return;
             var result = await window.StorageProvider.OpenFilePickerAsync(new Avalonia.Platform.Storage.FilePickerOpenOptions() { AllowMultiple = true });

samples/GpuInterop/DrawingSurfaceDemoBase.cs

@@ -71,12 +71,12 @@ async void Initialize()
     void UpdateFrame()
     {
         _updateQueued = false;
-        var root = this.GetVisualRoot();
-        if (root == null)
+        var source = this.GetPresentationSource();
+        if (source == null)
             return;
 
         _visual!.Size = new (Bounds.Width, Bounds.Height);
-        var size = PixelSize.FromSize(Bounds.Size, root.RenderScaling);
+        var size = PixelSize.FromSize(Bounds.Size, source.RenderScaling);
         RenderFrame(size);
         if (SupportsDisco && Disco > 0)
             QueueNextFrame();

src/Avalonia.Base/Input/AccessKeyHandler.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using Avalonia.Controls.Primitives;
 using Avalonia.Interactivity;
 using Avalonia.LogicalTree;
 using Avalonia.VisualTree;
@@ -30,6 +31,12 @@ internal class AccessKeyHandler : IAccessKeyHandler
                 RoutingStrategies.Bubble,
                 typeof(AccessKeyHandler));
 
+        /// <summary>
+        /// Defines the <see cref="ShowAccessKey"/> attached property.
+        /// </summary>
+        public static readonly AttachedProperty<bool> ShowAccessKeyProperty =
+            AvaloniaProperty.RegisterAttached<AccessKeyHandler, Visual, bool>("ShowAccessKey", inherits: true);
+
         /// <summary>
         /// The registered access keys.
         /// </summary>
@@ -40,7 +47,7 @@ internal class AccessKeyHandler : IAccessKeyHandler
         /// <summary>
         /// The window to which the handler belongs.
         /// </summary>
-        private IInputRoot? _owner;
+        private InputElement? _owner;
 
         /// <summary>
         /// Whether access keys are currently being shown;
@@ -96,7 +103,7 @@ public IMainMenu? MainMenu
         /// <remarks>
         /// This method can only be called once, typically by the owner itself on creation.
         /// </remarks>
-        public void SetOwner(IInputRoot owner)
+        public void SetOwner(InputElement owner)
         {
             if (_owner != null)
             {
@@ -113,7 +120,7 @@ public void SetOwner(IInputRoot owner)
             OnSetOwner(owner);
         }
 
-        protected virtual void OnSetOwner(IInputRoot owner)
+        protected virtual void OnSetOwner(InputElement owner)
         {
         }
 
@@ -159,6 +166,9 @@ public void Unregister(IInputElement element)
             }
         }
 
+        static void SetShowAccessKeys(AvaloniaObject target, bool value) =>
+            target.SetValue(ShowAccessKeyProperty, value);
+
         /// <summary>
         /// Called when a key is pressed in the owner window.
         /// </summary>
@@ -188,7 +198,7 @@ protected virtual void OnPreviewKeyDown(object? sender, KeyEventArgs e)
 
                     // When Alt is pressed without a main menu, or with a closed main menu, show
                     // access key markers in the window (i.e. "_File").
-                    _owner!.ShowAccessKeys = _showingAccessKeys = isFocusWithinOwner;
+                    SetShowAccessKeys(_owner!, _showingAccessKeys = isFocusWithinOwner);
                 }
                 else
                 {
@@ -265,7 +275,7 @@ protected virtual void OnPreviewPointerPressed(object? sender, PointerEventArgs
         {
             if (_showingAccessKeys)
             {
-                _owner!.ShowAccessKeys = false;
+                SetShowAccessKeys(_owner!, false);
             }
         }
 
@@ -275,12 +285,12 @@ protected virtual void OnPreviewPointerPressed(object? sender, PointerEventArgs
         private void CloseMenu()
         {
             MainMenu!.Close();
-            _owner!.ShowAccessKeys = _showingAccessKeys = false;
+            SetShowAccessKeys(_owner!, _showingAccessKeys = false);
         }
 
         private void MainMenuClosed(object? sender, EventArgs e)
         {
-            _owner!.ShowAccessKeys = false;
+            SetShowAccessKeys(_owner!, false);
         }
 
         /// <summary>
@@ -444,7 +454,7 @@ private static AccessKeyInformation GetTargetForElement(IInputElement? element,
         /// </summary>
         /// <param name="owner">The owner to check.</param>
         /// <returns>If focused element is decendant of owner <c>true</c>, otherwise <c>false</c>. </returns>
-        private static bool IsFocusWithinOwner(IInputRoot owner)
+        private static bool IsFocusWithinOwner(IInputElement owner)
         {
             var focusedElement = KeyboardDevice.Instance?.FocusedElement;
             if (focusedElement is not InputElement inputElement)

src/Avalonia.Base/Input/DragDropDevice.cs

@@ -16,7 +16,7 @@ public class DragDropDevice : IDragDropDevice
 
         private static Interactive? GetTarget(IInputRoot root, Point local)
         {
-            var hit = root.InputHitTest(local) as Visual;
+            var hit = root.RootElement?.InputHitTest(local) as Visual;
             var target = hit?.GetSelfAndVisualAncestors()?.OfType<Interactive>()?.FirstOrDefault();
             if (target != null && DragDrop.GetAllowDrop(target))
                 return target;

src/Avalonia.Base/Input/FocusManager.cs

@@ -51,6 +51,11 @@ public FocusManager(IInputElement contentRoot)
         {
             _contentRoot = contentRoot;
         }
+
+        internal void SetContentRoot(IInputElement? contentRoot)
+        {
+            _contentRoot = contentRoot;
+        }
 
         private IInputElement? Current => KeyboardDevice.Instance?.FocusedElement;
 
@@ -120,7 +125,7 @@ public void ClearFocusOnElementRemoved(IInputElement removedElement, Visual oldP
                 scope.ClearValue(FocusedElementProperty);
             }
 
-            if (Current == removedElement)
+            if (Current == removedElement) 
                 Focus(null);
         }
 
@@ -163,9 +168,10 @@ public void RemoveFocusRoot(IFocusScope scope)
         /// </summary>
         internal static FocusManager? GetFocusManager(IInputElement? element)
         {
+
             // Element might not be a visual, and not attached to the root.
             // But IFocusManager is always expected to be a FocusManager. 
-            return (FocusManager?)((element as Visual)?.VisualRoot as IInputRoot)?.FocusManager
+            return (FocusManager?)(element as Visual)?.GetInputRoot()?.FocusManager
                 // In our unit tests some elements might not have a root. Remove when we migrate to headless tests.
                 ?? (FocusManager?)AvaloniaLocator.Current.GetService<IFocusManager>();
         }

src/Avalonia.Base/Input/Gestures.cs

@@ -257,7 +257,7 @@ private static void PointerPressed(RoutedEventArgs ev)
                     s_lastPressPoint = e.GetPosition((Visual)source);
                     s_holdCancellationToken = new CancellationTokenSource();
                     var token = s_holdCancellationToken.Token;
-                    var settings = ((IInputRoot?)visual.GetVisualRoot())?.PlatformSettings;
+                    var settings = visual.GetPlatformSettings();
 
                     if (settings != null)
                     {
@@ -298,7 +298,7 @@ e.InitialPressMouseButton is MouseButton.Left or MouseButton.Right &&
                 source is Interactive i)
                 {
                     var point = e.GetCurrentPoint((Visual)target);
-                    var settings = ((IInputRoot?)i.GetVisualRoot())?.PlatformSettings;
+                    var settings = i.GetPlatformSettings();
                     var tapSize = settings?.GetTapSize(point.Pointer.Type) ?? new Size(4, 4);
                     var tapRect = new Rect(s_lastPressPoint, new Size())
                         .Inflate(new Thickness(tapSize.Width, tapSize.Height));
@@ -340,7 +340,6 @@ private static void PointerMoved(RoutedEventArgs ev)
                     if (e.Pointer == s_gestureState?.Pointer && source is Interactive i)
                     {
                         var point = e.GetCurrentPoint((Visual)target);
-                        var settings = ((IInputRoot?)i.GetVisualRoot())?.PlatformSettings;
                         var holdSize = new Size(4, 4);
                         var holdRect = new Rect(s_lastPressPoint, new Size())
                             .Inflate(new Thickness(holdSize.Width, holdSize.Height));

src/Avalonia.Base/Input/IAccessKeyHandler.cs

@@ -19,7 +19,7 @@ internal interface IAccessKeyHandler
         /// <remarks>
         /// This method can only be called once, typically by the owner itself on creation.
         /// </remarks>
-        void SetOwner(IInputRoot owner);
+        void SetOwner(InputElement owner);
 
         /// <summary>
         /// Registers an input element to be associated with an access key.

src/Avalonia.Base/Input/IInputRoot.cs

@@ -1,3 +1,4 @@
+using Avalonia.Input.TextInput;
 using Avalonia.Metadata;
 using Avalonia.Platform;
 
@@ -6,38 +7,24 @@ namespace Avalonia.Input
     /// <summary>
     /// Defines the interface for top-level input elements.
     /// </summary>
-    [NotClientImplementable]
-    public interface IInputRoot : IInputElement
+    [PrivateApi]
+    public interface IInputRoot
     {
-        /// <summary>
-        /// Gets or sets the keyboard navigation handler.
-        /// </summary>
-        IKeyboardNavigationHandler? KeyboardNavigationHandler { get; }
-
         /// <summary>
         /// Gets focus manager of the root.
         /// </summary>
         /// <remarks>
         /// Focus manager can be null only if window wasn't initialized yet.
         /// </remarks>
-        IFocusManager? FocusManager { get; }
-
-        /// <summary>
-        /// Represents a contract for accessing top-level platform-specific settings.
-        /// </summary>
-        /// <remarks>
-        /// PlatformSettings can be null only if window wasn't initialized yet.
-        /// </remarks>
-        IPlatformSettings? PlatformSettings { get; }
+        internal IFocusManager? FocusManager { get; }
 
         /// <summary>
         /// Gets or sets the input element that the pointer is currently over.
         /// </summary>
-        IInputElement? PointerOverElement { get; set; }
-
-        /// <summary>
-        /// Gets or sets a value indicating whether access keys are shown in the window.
-        /// </summary>
-        bool ShowAccessKeys { get; set; }
+        internal IInputElement? PointerOverElement { get; set; }
+
+        internal ITextInputMethodImpl? InputMethod { get; }
+
+        internal InputElement RootElement { get; }
     }
 }

src/Avalonia.Base/Input/IKeyboardNavigationHandler.cs

@@ -6,7 +6,7 @@ namespace Avalonia.Input
     /// Defines the interface for classes that handle keyboard navigation for a window.
     /// </summary>
     [Unstable]
-    public interface IKeyboardNavigationHandler
+    internal interface IKeyboardNavigationHandler
     {
         /// <summary>
         /// Sets the owner of the keyboard navigation handler.
@@ -16,7 +16,7 @@ public interface IKeyboardNavigationHandler
         /// This method can only be called once, typically by the owner itself on creation.
         /// </remarks>
         [PrivateApi]
-        void SetOwner(IInputRoot owner);
+        void SetOwner(InputElement owner);
 
         /// <summary>
         /// Moves the focus in the specified direction.

src/Avalonia.Base/Input/InputElement.cs

@@ -583,7 +583,8 @@ protected override void OnDetachedFromVisualTreeCore(VisualTreeAttachmentEventAr
 
             if (IsFocused)
             {
-                FocusManager.GetFocusManager(e.Root as IInputElement)?.ClearFocusOnElementRemoved(this, e.Parent);
+                ((FocusManager?)e.PresentationSource.InputRoot.FocusManager)?.ClearFocusOnElementRemoved(this,
+                    e.Parent ?? e.Root);
             }
 
             IsKeyboardFocusWithin = false;

src/Avalonia.Base/Input/KeyboardDevice.cs

@@ -191,15 +191,15 @@ public void SetFocusedElement(
                     // Clear keyboard focus from currently focused element
                     if (FocusedElement != null &&
                         (!((Visual)FocusedElement).IsAttachedToVisualTree ||
-                         _focusedRoot != ((Visual?)element)?.VisualRoot as IInputRoot) &&
+                         _focusedRoot != ((Visual?)element)?.GetInputRoot()) &&
                         _focusedRoot != null)
                     {
-                        ClearChildrenFocusWithin(_focusedRoot, true);
+                        ClearChildrenFocusWithin(_focusedRoot.RootElement, true);
                     }
 
                     SetIsFocusWithin(FocusedElement, element);
                     _focusedElement = element;
-                    _focusedRoot = ((Visual?)_focusedElement)?.VisualRoot as IInputRoot;
+                    _focusedRoot = (_focusedElement as Visual)?.GetInputRoot();
 
                     interactive?.RaiseEvent(new RoutedEventArgs(InputElement.LostFocusEvent));
 
@@ -225,7 +225,7 @@ public void ProcessRawEvent(RawInputEventArgs e)
             if(e.Handled)
                 return;
 
-            var element = FocusedElement ?? e.Root;
+            var element = FocusedElement ?? e.Root.RootElement;
 
             if (e is RawKeyEventArgs keyInput)
             {

src/Avalonia.Base/Input/KeyboardNavigationHandler.cs

@@ -11,12 +11,12 @@ namespace Avalonia.Input
     /// Handles keyboard navigation for a window.
     /// </summary>
     [Unstable]
-    public sealed class KeyboardNavigationHandler : IKeyboardNavigationHandler
+    internal sealed class KeyboardNavigationHandler : IKeyboardNavigationHandler
     {
         /// <summary>
         /// The window to which the handler belongs.
         /// </summary>
-        private IInputRoot? _owner;
+        private InputElement? _owner;
 
         /// <summary>
         /// Sets the owner of the keyboard navigation handler.
@@ -26,7 +26,7 @@ public sealed class KeyboardNavigationHandler : IKeyboardNavigationHandler
         /// This method can only be called once, typically by the owner itself on creation.
         /// </remarks>
         [PrivateApi]
-        public void SetOwner(IInputRoot owner)
+        public void SetOwner(InputElement owner)
         {
             if (_owner != null)
             {
@@ -56,7 +56,7 @@ public void SetOwner(IInputRoot owner)
 
         private static IInputElement? GetNextPrivate(
             IInputElement? element,
-            IInputRoot? owner,
+            InputElement? owner,
             NavigationDirection direction,
             KeyDeviceType? keyDeviceType)
         {