Extract theme related properties to IThemeVariantHost and move property definitions to ThemeVariantScope

src/Avalonia.Base/Controls/ResourceNodeExtensions.cs

@@ -138,18 +138,18 @@ namespace Avalonia.Controls
             protected override void Initialize()
             {
                 _target.ResourcesChanged += ResourcesChanged;
-                if (_target is StyledElement themeStyleable)
+                if (_target is IThemeVariantHost themeVariantHost)
                 {
-                    themeStyleable.PropertyChanged += PropertyChanged;
+                    themeVariantHost.ActualThemeVariantChanged += ActualThemeVariantChanged;
                 }
             }
 
             protected override void Deinitialize()
             {
                 _target.ResourcesChanged -= ResourcesChanged;
-                if (_target is StyledElement themeStyleable)
+                if (_target is IThemeVariantHost themeVariantHost)
                 {
-                    themeStyleable.PropertyChanged -= PropertyChanged;
+                    themeVariantHost.ActualThemeVariantChanged -= ActualThemeVariantChanged;
                 }
             }
 
@@ -163,18 +163,15 @@ namespace Avalonia.Controls
                 PublishNext(GetValue());
             }
 
-            private void PropertyChanged(object? sender, AvaloniaPropertyChangedEventArgs e)
+            private void ActualThemeVariantChanged(object? sender, EventArgs e)
             {
-                if (e.Property == StyledElement.ActualThemeVariantProperty)
-                {
-                    PublishNext(GetValue());
-                }
+                PublishNext(GetValue());
             }
 
             private object? GetValue()
             {
-                if (_target is not StyledElement themeStyleable
-                    || !_target.TryFindResource(_key, themeStyleable.ActualThemeVariant, out var value))
+                if (_target is not IThemeVariantHost themeVariantHost
+                    || !_target.TryFindResource(_key, themeVariantHost.ActualThemeVariant, out var value))
                 {
                     value = _target.FindResource(_key) ?? AvaloniaProperty.UnsetValue;
                 }
@@ -236,9 +233,9 @@ namespace Avalonia.Controls
                 {
                     _owner.ResourcesChanged -= ResourcesChanged;
                 }
-                if (_owner is StyledElement styleable)
+                if (_owner is IThemeVariantHost themeVariantHost)
                 {
-                    styleable.PropertyChanged += PropertyChanged;
+                    themeVariantHost.ActualThemeVariantChanged += ActualThemeVariantChanged;
                 }
 
                 _owner = _target.Owner;
@@ -247,20 +244,18 @@ namespace Avalonia.Controls
                 {
                     _owner.ResourcesChanged += ResourcesChanged;
                 }
-                if (_owner is StyledElement styleable2)
+                if (_owner is IThemeVariantHost themeVariantHost2)
                 {
-                    styleable2.PropertyChanged += PropertyChanged;
+                    themeVariantHost2.ActualThemeVariantChanged -= ActualThemeVariantChanged;
                 }
 
+
                 PublishNext();
             }
 
-            private void PropertyChanged(object? sender, AvaloniaPropertyChangedEventArgs e)
+            private void ActualThemeVariantChanged(object? sender, EventArgs e)
             {
-                if (e.Property == StyledElement.ActualThemeVariantProperty)
-                {
-                    PublishNext();
-                }
+                PublishNext();
             }
 
             private void ResourcesChanged(object? sender, ResourcesChangedEventArgs e)
@@ -270,8 +265,8 @@ namespace Avalonia.Controls
 
             private object? GetValue()
             {
-                if (!(_target.Owner is StyledElement themeStyleable)
-                    || !_target.Owner.TryFindResource(_key, themeStyleable.ActualThemeVariant, out var value))
+                if (!(_target.Owner is IThemeVariantHost themeVariantHost)
+                    || !_target.Owner.TryFindResource(_key, themeVariantHost.ActualThemeVariant, out var value))
                 {
                     value = _target.Owner?.FindResource(_key) ?? AvaloniaProperty.UnsetValue;
                 }

src/Avalonia.Base/StyledElement.cs

@@ -71,23 +71,6 @@ namespace Avalonia
         public static readonly StyledProperty<ControlTheme?> ThemeProperty =
             AvaloniaProperty.Register<StyledElement, ControlTheme?>(nameof(Theme));
 
-        /// <summary>
-        /// Defines the <see cref="ActualThemeVariant"/> property.
-        /// </summary>
-        public static readonly StyledProperty<ThemeVariant> ActualThemeVariantProperty =
-            AvaloniaProperty.Register<StyledElement, ThemeVariant>(
-                nameof(ThemeVariant),
-                inherits: true,
-                defaultValue: ThemeVariant.Light);
-
-        /// <summary>
-        /// Defines the RequestedThemeVariant property.
-        /// </summary>
-        public static readonly StyledProperty<ThemeVariant?> RequestedThemeVariantProperty =
-            AvaloniaProperty.Register<StyledElement, ThemeVariant?>(
-                nameof(ThemeVariant),
-                defaultValue: ThemeVariant.Default);
-
         private static readonly ControlTheme s_invalidTheme = new ControlTheme();
         private int _initCount;
         private string? _name;
@@ -274,15 +257,6 @@ namespace Avalonia
             set => SetValue(ThemeProperty, value);
         }
 
-        /// <summary>
-        /// Gets the UI theme that is currently used by the element, which might be different than the <see cref="RequestedThemeVariantProperty"/>.
-        /// </summary>
-        /// <returns>
-        /// If current control is contained in the ThemeVariantScope, TopLevel or Application with non-default RequestedThemeVariant, that value will be returned.
-        /// Otherwise, current OS theme variant is returned.
-        /// </returns>
-        public ThemeVariant ActualThemeVariant => GetValue(ActualThemeVariantProperty);
-
         /// <summary>
         /// Gets the styled element's logical children.
         /// </summary>
@@ -647,13 +621,6 @@ namespace Avalonia
 
             if (change.Property == ThemeProperty)
                 OnControlThemeChanged();
-            else if (change.Property == RequestedThemeVariantProperty)
-            {
-                if (change.GetNewValue<ThemeVariant>() is {} themeVariant && themeVariant != ThemeVariant.Default)
-                    SetValue(ActualThemeVariantProperty, themeVariant);
-                else
-                    ClearValue(ActualThemeVariantProperty);
-            }
         }
 
         private protected virtual void OnControlThemeChanged()

src/Avalonia.Base/Styling/IGlobalThemeVariantProvider.cs

@@ -1,22 +0,0 @@
-using System;
-using Avalonia.Controls;
-using Avalonia.Metadata;
-
-namespace Avalonia.Styling;
-
-/// <summary>
-/// Interface for an application host element with a root theme variant.
-/// </summary>
-[Unstable]
-public interface IGlobalThemeVariantProvider : IResourceHost
-{
-    /// <summary>
-    /// Gets the UI theme variant that is used by the control (and its child elements) for resource determination.
-    /// </summary>
-    ThemeVariant ActualThemeVariant { get; }
-
-    /// <summary>
-    /// Raised when the theme variant is changed on the element or an ancestor of the element.
-    /// </summary>
-    event EventHandler? ActualThemeVariantChanged;
-}

src/Avalonia.Base/Styling/IThemeVariantHost.cs

@@ -0,0 +1,26 @@
+using System;
+using Avalonia.Controls;
+using Avalonia.Metadata;
+
+namespace Avalonia.Styling;
+
+/// <summary>
+/// Interface for the host element with a theme variant.
+/// </summary>
+[Unstable]
+public interface IThemeVariantHost : IResourceHost
+{
+    /// <summary>
+    /// Gets the UI theme that is currently used by the element, which might be different than the RequestedThemeVariantProperty.
+    /// </summary>
+    /// <returns>
+    /// If current control is contained in the ThemeVariantScope, TopLevel or Application with non-default RequestedThemeVariant, that value will be returned.
+    /// Otherwise, current OS theme variant is returned.
+    /// </returns>
+    ThemeVariant ActualThemeVariant { get; }
+
+    /// <summary>
+    /// Raised when the theme variant is changed on the element or an ancestor of the element.
+    /// </summary>
+    event EventHandler? ActualThemeVariantChanged;
+}

src/Avalonia.Controls/Application.cs

@@ -29,7 +29,7 @@ namespace Avalonia
     /// method.
     /// - Tracks the lifetime of the application.
     /// </remarks>
-    public class Application : AvaloniaObject, IDataContextProvider, IGlobalDataTemplates, IGlobalStyles, IGlobalThemeVariantProvider, IApplicationPlatformEvents
+    public class Application : AvaloniaObject, IDataContextProvider, IGlobalDataTemplates, IGlobalStyles, IThemeVariantHost, IApplicationPlatformEvents
     {
         /// <summary>
         /// The application-global data templates.
@@ -50,13 +50,13 @@ namespace Avalonia
         public static readonly StyledProperty<object?> DataContextProperty =
             StyledElement.DataContextProperty.AddOwner<Application>();
 
-        /// <inheritdoc cref="StyledElement.ActualThemeVariantProperty" />
+        /// <inheritdoc cref="ThemeVariantScope.ActualThemeVariantProperty" />
         public static readonly StyledProperty<ThemeVariant> ActualThemeVariantProperty =
-            StyledElement.ActualThemeVariantProperty.AddOwner<Application>();
+            ThemeVariantScope.ActualThemeVariantProperty.AddOwner<Application>();
         
-        /// <inheritdoc cref="StyledElement.RequestedThemeVariantProperty" />
+        /// <inheritdoc cref="ThemeVariantScope.RequestedThemeVariantProperty" />
         public static readonly StyledProperty<ThemeVariant?> RequestedThemeVariantProperty =
-            StyledElement.RequestedThemeVariantProperty.AddOwner<Application>();
+            ThemeVariantScope.RequestedThemeVariantProperty.AddOwner<Application>();
 
         /// <inheritdoc/>
         public event EventHandler<ResourcesChangedEventArgs>? ResourcesChanged;
@@ -95,11 +95,8 @@ namespace Avalonia
             set => SetValue(RequestedThemeVariantProperty, value);
         }
         
-        /// <inheritdoc cref="StyledElement.ActualThemeVariant"/>
-        public ThemeVariant ActualThemeVariant
-        {
-            get => GetValue(ActualThemeVariantProperty);
-        } 
+        /// <inheritdoc cref="ThemeVariantScope.ActualThemeVariant"/>
+        public ThemeVariant ActualThemeVariant => GetValue(ActualThemeVariantProperty);
 
         /// <summary>
         /// Gets the current instance of the <see cref="Application"/> class.
@@ -256,7 +253,7 @@ namespace Avalonia
                 .Bind<IAccessKeyHandler>().ToTransient<AccessKeyHandler>()
                 .Bind<IGlobalDataTemplates>().ToConstant(this)
                 .Bind<IGlobalStyles>().ToConstant(this)
-                .Bind<IGlobalThemeVariantProvider>().ToConstant(this)
+                .Bind<IThemeVariantHost>().ToConstant(this)
                 .Bind<IFocusManager>().ToConstant(FocusManager)
                 .Bind<IInputManager>().ToConstant(InputManager)
                 .Bind<IKeyboardNavigationHandler>().ToTransient<KeyboardNavigationHandler>()

src/Avalonia.Controls/Control.cs

@@ -26,7 +26,7 @@ namespace Avalonia.Controls
     /// - A <see cref="Tag"/> property to allow user-defined data to be attached to the control.
     /// - <see cref="ContextRequestedEvent"/> and other context menu related members.
     /// </remarks>
-    public class Control : InputElement, IDataTemplateHost, INamed, IVisualBrushInitialize, ISetterValue
+    public class Control : InputElement, IDataTemplateHost, INamed, IVisualBrushInitialize, ISetterValue, IThemeVariantHost
     {
         /// <summary>
         /// Defines the <see cref="FocusAdorner"/> property.
@@ -163,6 +163,10 @@ namespace Avalonia.Controls
             get => GetValue(TagProperty);
             set => SetValue(TagProperty, value);
         }
+        
+        public ThemeVariant ActualThemeVariant => GetValue(ThemeVariantScope.ActualThemeVariantProperty);
+
+        public event EventHandler? ActualThemeVariantChanged;
 
         /// <summary>
         /// Occurs when the user has completed a context input gesture, such as a right-click.
@@ -530,6 +534,17 @@ namespace Avalonia.Controls
                     RaiseEvent(sizeChangedEventArgs);
                 }
             }
+            else if (change.Property == ThemeVariantScope.RequestedThemeVariantProperty)
+            {
+                if (change.GetNewValue<ThemeVariant>() is {} themeVariant && themeVariant != ThemeVariant.Default)
+                    SetValue(ThemeVariantScope.ActualThemeVariantProperty, themeVariant);
+                else
+                    ClearValue(ThemeVariantScope.ActualThemeVariantProperty);
+            }
+            else if (change.Property == ThemeVariantScope.ActualThemeVariantProperty)
+            {
+                ActualThemeVariantChanged?.Invoke(this, EventArgs.Empty);
+            }
         }
     }
 }

src/Avalonia.Controls/ThemeVariantScope.cs

@@ -7,6 +7,23 @@ namespace Avalonia.Controls
     /// </summary>
     public class ThemeVariantScope : Decorator
     {
+        /// <summary>
+        /// Defines the <see cref="StyledElement.ActualThemeVariant"/> property.
+        /// </summary>
+        public static readonly StyledProperty<ThemeVariant> ActualThemeVariantProperty =
+            AvaloniaProperty.Register<ThemeVariantScope, ThemeVariant>(
+                nameof(ThemeVariant),
+                inherits: true,
+                defaultValue: ThemeVariant.Light);
+
+        /// <summary>
+        /// Defines the <see cref="RequestedThemeVariant"/> property.
+        /// </summary>
+        public static readonly StyledProperty<ThemeVariant?> RequestedThemeVariantProperty =
+            AvaloniaProperty.Register<ThemeVariantScope, ThemeVariant?>(
+                nameof(ThemeVariant),
+                defaultValue: ThemeVariant.Default);
+        
         /// <summary>
         /// Gets or sets the UI theme variant that is used by the control (and its child elements) for resource determination.
         /// The UI theme you specify with ThemeVariant can override the app-level ThemeVariant.

src/Avalonia.Controls/TopLevel.cs

@@ -79,6 +79,14 @@ namespace Avalonia.Controls
         public static readonly StyledProperty<IBrush> TransparencyBackgroundFallbackProperty =
             AvaloniaProperty.Register<TopLevel, IBrush>(nameof(TransparencyBackgroundFallback), Brushes.White);
 
+        /// <inheritdoc cref="ThemeVariantScope.ActualThemeVariantProperty" />
+        public static readonly StyledProperty<ThemeVariant> ActualThemeVariantProperty =
+            ThemeVariantScope.ActualThemeVariantProperty.AddOwner<Application>();
+        
+        /// <inheritdoc cref="ThemeVariantScope.RequestedThemeVariantProperty" />
+        public static readonly StyledProperty<ThemeVariant?> RequestedThemeVariantProperty =
+            ThemeVariantScope.RequestedThemeVariantProperty.AddOwner<Application>();
+        
         /// <summary>
         /// Defines the <see cref="BackRequested"/> event.
         /// </summary>
@@ -96,7 +104,7 @@ namespace Avalonia.Controls
         private readonly IKeyboardNavigationHandler? _keyboardNavigationHandler;
         private readonly IPlatformRenderInterface? _renderInterface;
         private readonly IGlobalStyles? _globalStyles;
-        private readonly IGlobalThemeVariantProvider? _applicationThemeHost;
+        private readonly IThemeVariantHost? _applicationThemeHost;
         private readonly PointerOverPreProcessor? _pointerOverPreProcessor;
         private readonly IDisposable? _pointerOverPreProcessorSubscription;
         private readonly IDisposable? _backGestureSubscription;
@@ -153,7 +161,7 @@ namespace Avalonia.Controls
             _keyboardNavigationHandler = TryGetService<IKeyboardNavigationHandler>(dependencyResolver);
             _renderInterface = TryGetService<IPlatformRenderInterface>(dependencyResolver);
             _globalStyles = TryGetService<IGlobalStyles>(dependencyResolver);
-            _applicationThemeHost = TryGetService<IGlobalThemeVariantProvider>(dependencyResolver);
+            _applicationThemeHost = TryGetService<IThemeVariantHost>(dependencyResolver);
 
             Renderer = impl.CreateRenderer(this);
 
@@ -633,7 +641,7 @@ namespace Avalonia.Controls
 
         private void GlobalActualThemeVariantChanged(object? sender, EventArgs e)
         {
-            SetValue(ActualThemeVariantProperty, ((IGlobalThemeVariantProvider)sender!).ActualThemeVariant, BindingPriority.Template);
+            SetValue(ActualThemeVariantProperty, ((IThemeVariantHost)sender!).ActualThemeVariant, BindingPriority.Template);
         }
 
         private void SceneInvalidated(object? sender, SceneInvalidatedEventArgs e)

src/Avalonia.Diagnostics/Diagnostics/Controls/Application.cs

@@ -14,7 +14,7 @@ namespace Avalonia.Diagnostics.Controls
         public event EventHandler? Closed;
 
         public static readonly StyledProperty<ThemeVariant?> RequestedThemeVariantProperty =
-            StyledElement.RequestedThemeVariantProperty.AddOwner<Application>();
+            ThemeVariantScope.RequestedThemeVariantProperty.AddOwner<Application>();
         
         public Application(Avalonia.Application application)
         {

src/Markup/Avalonia.Markup.Xaml/MarkupExtensions/StaticResourceExtension.cs

@@ -34,7 +34,7 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions
 
             var stack = serviceProvider.GetService<IAvaloniaXamlIlParentStackProvider>();
             var provideTarget = serviceProvider.GetService<IProvideValueTarget>();
-            var themeVariant = (provideTarget.TargetObject as StyledElement)?.ActualThemeVariant;
+            var themeVariant = (provideTarget.TargetObject as IThemeVariantHost)?.ActualThemeVariant;
 
             var targetType = provideTarget.TargetProperty switch
             {

tests/Avalonia.Markup.Xaml.UnitTests/Xaml/ThemeDictionariesTests.cs

@@ -185,9 +185,9 @@ public class ThemeDictionariesTests : XamlTestBase
     {
         using (AvaloniaLocator.EnterScope())
         {
-            var applicationThemeHost = new Mock<IGlobalThemeVariantProvider>();
+            var applicationThemeHost = new Mock<IThemeVariantHost>();
             applicationThemeHost.SetupGet(h => h.ActualThemeVariant).Returns(ThemeVariant.Dark);
-            AvaloniaLocator.CurrentMutable.Bind<IGlobalThemeVariantProvider>().ToConstant(applicationThemeHost.Object);
+            AvaloniaLocator.CurrentMutable.Bind<IThemeVariantHost>().ToConstant(applicationThemeHost.Object);
 
             var themeVariantScope = (ThemeVariantScope)AvaloniaRuntimeXamlLoader.Load(@"
 <ThemeVariantScope xmlns='https://github.com/avaloniaui'