fix: Re-evaluate visual state setters on theme change

src/Uno.UI.RuntimeTests/Tests/Windows_UI_Xaml_Controls/Given_PersonPicture.cs

@@ -0,0 +1,50 @@
+using System.Threading.Tasks;
+using Microsoft.UI.Xaml.Controls;
+using Private.Infrastructure;
+using SamplesApp.UITests;
+using Uno.UI.RuntimeTests.Helpers;
+using PersonPicture = Microsoft/* UWP don't rename */.UI.Xaml.Controls.PersonPicture;
+
+namespace Uno.UI.RuntimeTests.Tests.Windows_UI_Xaml_Controls;
+
+[TestClass]
+[RunsOnUIThread]
+public partial class Given_PersonPicture
+{
+	private partial class MyPersonPicture : PersonPicture
+	{
+		public TextBlock InitialsTextBlock { get; private set; }
+
+		protected override void OnApplyTemplate()
+		{
+			base.OnApplyTemplate();
+			InitialsTextBlock = (TextBlock)GetTemplateChild("InitialsTextBlock");
+		}
+	}
+
+	[TestMethod]
+	[UnoWorkItem("https://github.com/unoplatform/uno/issues/16006")]
+	public async Task TestInitialsTextBlockFontFamily()
+	{
+		var personPicture = new MyPersonPicture();
+		await UITestHelper.Load(personPicture);
+
+#if WINAPPSDK
+		string symbolsFontName = "Segoe MDL2 Assets";
+#else
+		string symbolsFontName = "ms-appx:///Uno.Fonts.Fluent/Fonts/uno-fluentui-assets.ttf";
+#endif
+
+		var fontFamilyLight = personPicture.InitialsTextBlock.FontFamily.Source;
+		Assert.AreEqual(symbolsFontName, fontFamilyLight);
+
+		using (ThemeHelper.UseDarkTheme())
+		{
+			Assert.AreEqual(fontFamilyLight, personPicture.InitialsTextBlock.FontFamily.Source);
+			await TestServices.WindowHelper.WaitForIdle();
+			Assert.AreEqual(fontFamilyLight, personPicture.InitialsTextBlock.FontFamily.Source);
+		}
+
+		Assert.AreEqual(fontFamilyLight, personPicture.InitialsTextBlock.FontFamily.Source);
+	}
+}

src/Uno.UI.RuntimeTests/Tests/Windows_UI_Xaml_Media_Animation/Given_TemplateBindingAfterAnimation.cs

@@ -0,0 +1,73 @@
+using System.Threading.Tasks;
+using Microsoft.UI.Xaml.Media;
+using Private.Infrastructure;
+using Uno.UI.RuntimeTests.Helpers;
+using Uno.UI.RuntimeTests.Tests.Windows_UI_Xaml_Media_Animation.TestPages;
+
+namespace Uno.UI.RuntimeTests.Tests.Windows_UI_Xaml_Media_Animation;
+
+[TestClass]
+[RunsOnUIThread]
+internal class Given_TemplateBindingAfterAnimation
+{
+	[TestMethod]
+	public async Task When_TemplateBinding_And_Animation_Set_Local_On_TemplatedParent()
+	{
+		// Scenario being tested:
+		// - CustomButton style sets Foreground to Blue
+		// - A visual state sets tb1.Foreground to Red (we call GoToState in OnApplyTemplate)
+		// - tb1 Foreground has TemplateBinding to CustomButton's Foreground
+		var page = new TemplateBindingAfterAnimationPage();
+
+		await UITestHelper.Load(page);
+
+		var btn = page.customButton;
+		var tb1 = btn.TextBlockTemplateChildBoundToForeground;
+
+		Assert.AreEqual((btn.Foreground as SolidColorBrush).Color, Microsoft.UI.Colors.Blue);
+		Assert.AreEqual((tb1.Foreground as SolidColorBrush).Color, Microsoft.UI.Colors.Red);
+
+		btn.Foreground = new SolidColorBrush(Microsoft.UI.Colors.Green);
+
+		Assert.AreEqual((btn.Foreground as SolidColorBrush).Color, Microsoft.UI.Colors.Green);
+		Assert.AreEqual((tb1.Foreground as SolidColorBrush).Color, Microsoft.UI.Colors.Green);
+
+		await TestServices.WindowHelper.WaitForIdle();
+
+		Assert.AreEqual((btn.Foreground as SolidColorBrush).Color, Microsoft.UI.Colors.Green);
+		Assert.AreEqual((tb1.Foreground as SolidColorBrush).Color, Microsoft.UI.Colors.Green);
+	}
+
+	[TestMethod]
+	public async Task When_TemplateBinding_And_Animation_Change_Theme()
+	{
+		// Scenario being tested:
+		// - CustomButton style sets Background to {ThemeResource TemplateBindingAfterAnimationThemeColor1} (Light=White, Dark=LightGray)
+		// - A visual state sets tb2.Foreground to {ThemeResource TemplateBindingAfterAnimationThemeColor2} (Light=Brown, Dark=RosyBrown) (we call GoToState in OnApplyTemplate)
+		// - tb2 Foreground has TemplateBinding to CustomButton's Background
+		var page = new TemplateBindingAfterAnimationPage();
+
+		await UITestHelper.Load(page);
+
+		var btn = page.customButton;
+		var tb2 = btn.TextBlockTemplateChildBoundToBackground;
+
+		Assert.AreEqual((btn.Background as SolidColorBrush).Color, Microsoft.UI.Colors.White);
+		Assert.AreEqual((tb2.Foreground as SolidColorBrush).Color, Microsoft.UI.Colors.Brown);
+
+		using (ThemeHelper.UseDarkTheme())
+		{
+			Assert.AreEqual((btn.Background as SolidColorBrush).Color, Microsoft.UI.Colors.LightGray);
+
+#if HAS_UNO
+			Assert.AreEqual((tb2.Foreground as SolidColorBrush).Color, Microsoft.UI.Colors.RosyBrown);
+#else
+			Assert.AreEqual((tb2.Foreground as SolidColorBrush).Color, Microsoft.UI.Colors.LightGray);
+#endif
+
+			await TestServices.WindowHelper.WaitForIdle();
+
+			Assert.AreEqual((tb2.Foreground as SolidColorBrush).Color, Microsoft.UI.Colors.RosyBrown);
+		}
+	}
+}

src/Uno.UI.RuntimeTests/Tests/Windows_UI_Xaml_Media_Animation/TestPages/TemplateBindingAfterAnimationPage.xaml

@@ -0,0 +1,53 @@
+<Page
+    x:Class="Uno.UI.RuntimeTests.Tests.Windows_UI_Xaml_Media_Animation.TestPages.TemplateBindingAfterAnimationPage"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:local="using:Uno.UI.RuntimeTests.Tests.Windows_UI_Xaml_Media_Animation.TestPages"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    mc:Ignorable="d"
+    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
+
+	<Grid>
+		<Grid.Resources>
+			<ResourceDictionary>
+				<ResourceDictionary.ThemeDictionaries>
+					<ResourceDictionary x:Key="Light">
+						<SolidColorBrush x:Key="TemplateBindingAfterAnimationThemeColor1" Color="White" />
+						<SolidColorBrush x:Key="TemplateBindingAfterAnimationThemeColor2" Color="Brown" />
+					</ResourceDictionary>
+					<ResourceDictionary x:Key="Dark">
+						<SolidColorBrush x:Key="TemplateBindingAfterAnimationThemeColor1" Color="LightGray" />
+						<SolidColorBrush x:Key="TemplateBindingAfterAnimationThemeColor2" Color="RosyBrown" />
+					</ResourceDictionary>
+				</ResourceDictionary.ThemeDictionaries>
+
+				<Style x:Key="TemplateBindingAfterAnimationStyle" TargetType="local:CustomButton">
+					<Setter Property="Foreground" Value="Blue" />
+					<Setter Property="Background" Value="{ThemeResource TemplateBindingAfterAnimationThemeColor1}" />
+					<Setter Property="Template">
+						<Setter.Value>
+							<ControlTemplate TargetType="local:CustomButton">
+								<StackPanel>
+									<TextBlock x:Name="tb1" Foreground="{TemplateBinding Foreground}" Text="Foreground bound to Foreground" />
+									<TextBlock x:Name="tb2" Foreground="{TemplateBinding Background}" Text="Foreground bound to Background" />
+									<VisualStateManager.VisualStateGroups>
+										<VisualStateGroup x:Name="MyVSGroup">
+											<VisualState x:Name="MyState">
+												<VisualState.Setters>
+													<Setter Target="tb1.Foreground" Value="Red" />
+													<Setter Target="tb2.Foreground" Value="{ThemeResource TemplateBindingAfterAnimationThemeColor2}" />
+												</VisualState.Setters>
+											</VisualState>
+										</VisualStateGroup>
+									</VisualStateManager.VisualStateGroups>
+								</StackPanel>
+							</ControlTemplate>
+						</Setter.Value>
+					</Setter>
+				</Style>
+			</ResourceDictionary>
+		</Grid.Resources>
+		<local:CustomButton Style="{StaticResource TemplateBindingAfterAnimationStyle}" x:FieldModifier="public" x:Name="customButton" />
+	</Grid>
+</Page>

src/Uno.UI.RuntimeTests/Tests/Windows_UI_Xaml_Media_Animation/TestPages/TemplateBindingAfterAnimationPage.xaml.cs

@@ -0,0 +1,26 @@
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Controls;
+
+namespace Uno.UI.RuntimeTests.Tests.Windows_UI_Xaml_Media_Animation.TestPages;
+
+public sealed partial class TemplateBindingAfterAnimationPage : Page
+{
+	public TemplateBindingAfterAnimationPage()
+	{
+		this.InitializeComponent();
+	}
+}
+
+public partial class CustomButton : Button
+{
+	public TextBlock TextBlockTemplateChildBoundToForeground { get; private set; }
+	public TextBlock TextBlockTemplateChildBoundToBackground { get; private set; }
+
+	protected override void OnApplyTemplate()
+	{
+		base.OnApplyTemplate();
+		TextBlockTemplateChildBoundToForeground = (TextBlock)this.GetTemplateChild("tb1");
+		TextBlockTemplateChildBoundToBackground = (TextBlock)this.GetTemplateChild("tb2");
+		VisualStateManager.GoToState(this, "MyState", false);
+	}
+}

src/Uno.UI/UI/Xaml/DependencyPropertyDetails.cs

@@ -282,6 +282,18 @@ internal void ClearBinding()
 			}
 			else
 			{
+				if (precedence == DependencyPropertyValuePrecedences.Animations && (_flags & Flags.LocalValueNewerThanAnimationsValue) != 0)
+				{
+					// When setting BindingPath.Value, we do the following check:
+					// DependencyObjectStore.AreDifferent(value, _value.GetPrecedenceSpecificValue())
+					// Now, consider the following case:
+					// Animation value set to some value x, then Local value is set to some value y,
+					// then BindingPath.Value is trying to set Animation value to x
+					// in this case, we want to consider the values as different.
+					// So, we need to return the Local value when we are asked for Animation as the Local value is effectively overwriting the animation value.
+					precedence = DependencyPropertyValuePrecedences.Local;
+				}
+
 				return Unwrap(Stack[(int)precedence]);
 			}
 		}

src/Uno.UI/UI/Xaml/FrameworkElement.cs

@@ -21,6 +21,7 @@
 using Windows.UI.Core;
 using System.ComponentModel;
 using Uno.UI.DataBinding;
+using Uno.UI.Dispatching;
 using Uno.UI.Xaml;
 using Microsoft.UI.Xaml.Media;
 using Microsoft.UI.Xaml.Data;
@@ -883,6 +884,15 @@ internal virtual void UpdateThemeBindings(ResourceUpdateReason updateReason)
 				{
 					ActualThemeChanged?.Invoke(this, null);
 				}
+
+				if (this is Control @this && @this.GetTemplateRoot() is { } templateRoot)
+				{
+					var groups = VisualStateManager.GetVisualStateGroups(templateRoot);
+					foreach (var group in groups)
+					{
+						NativeDispatcher.Main.Enqueue(() => group.ReevaluateAppliedPropertySetters(@this));
+					}
+				}
 			}
 		}
 

src/Uno.UI/UI/Xaml/VisualStateGroup.cs

@@ -141,6 +141,28 @@ private void VisualStateChanged(object sender, IVectorChangedEventArgs e)
 			RefreshStateTriggers();
 		}
 
+		internal void ReevaluateAppliedPropertySetters(Control control)
+		{
+			var state = VisualStateManager.GetCurrentState(control, Name);
+			if (state is null)
+			{
+				return;
+			}
+
+			try
+			{
+				ResourceResolver.PushNewScope(_xamlScope);
+				foreach (var setter in state.Setters)
+				{
+					(setter as Setter)?.ApplyValue(DependencyPropertyValuePrecedences.Animations, control);
+				}
+			}
+			finally
+			{
+				ResourceResolver.PopScope();
+			}
+		}
+
 		private void OnParentChanged(object instance, object key, DependencyObjectParentChangedEventArgs args)
 		{
 			RefreshStateTriggers(force: true);