Cache the dynamic AppTheme value in Controls (and not Essentials)

src/Controls/samples/Controls.Sample/Platforms/Android/MainActivity.cs

@@ -14,7 +14,7 @@ namespace Maui.Controls.Sample.Platform
 		| ConfigChanges.UiMode
 		| ConfigChanges.SmallestScreenSize
 		| ConfigChanges.KeyboardHidden
-	| ConfigChanges.Density
+		| ConfigChanges.Density
 		)]
 	[IntentFilter(
 		new[] { Microsoft.Maui.ApplicationModel.Platform.Intent.ActionAppAction },

src/Controls/src/Core/Application.cs

@@ -51,7 +51,8 @@ internal Application(bool setCurrentApplication)
 
 			_platformConfigurationRegistry = new Lazy<PlatformConfigurationRegistry<Application>>(() => new PlatformConfigurationRegistry<Application>(this));
 
-			_lastAppTheme = PlatformAppTheme;
+			_platformAppTheme = AppInfo.RequestedTheme;
+			_lastAppTheme = _platformAppTheme;
 		}
 
 		/// <include file="../../docs/Microsoft.Maui.Controls/Application.xml" path="//Member[@MemberName='Quit']/Docs/*" />
@@ -164,15 +165,34 @@ public AppTheme UserAppTheme
 			get => _userAppTheme;
 			set
 			{
+				if (_userAppTheme == value)
+					return;
+
 				_userAppTheme = value;
+
 				TriggerThemeChangedActual();
 			}
 		}
 
-		public AppTheme PlatformAppTheme => AppInfo.RequestedTheme;
+		public AppTheme PlatformAppTheme
+		{
+			get => _platformAppTheme;
+			private set
+			{
+				if (_platformAppTheme == value)
+					return;
+
+				_platformAppTheme = value;
+
+				TriggerThemeChangedActual();
+			}
+		}
 
 		/// <include file="../../docs/Microsoft.Maui.Controls/Application.xml" path="//Member[@MemberName='RequestedTheme']/Docs/*" />
-		public AppTheme RequestedTheme => UserAppTheme != AppTheme.Unspecified ? UserAppTheme : PlatformAppTheme;
+		public AppTheme RequestedTheme =>
+			UserAppTheme != AppTheme.Unspecified
+				? UserAppTheme
+				: PlatformAppTheme;
 
 		static Color? _accentColor;
 		public static Color? AccentColor
@@ -211,6 +231,7 @@ public event EventHandler<AppThemeChangedEventArgs> RequestedThemeChanged
 		}
 
 		bool _themeChangedFiring;
+		AppTheme _platformAppTheme = AppTheme.Unspecified;
 		AppTheme _lastAppTheme = AppTheme.Unspecified;
 		AppTheme _userAppTheme = AppTheme.Unspecified;
 

src/Controls/src/Core/HandlerImpl/Application/Application.Impl.cs

@@ -111,10 +111,7 @@ public virtual void CloseWindow(Window window)
 
 		void IApplication.ThemeChanged()
 		{
-			if (UserAppTheme != AppTheme.Unspecified)
-				return;
-
-			TriggerThemeChangedActual();
+			PlatformAppTheme = AppInfo.RequestedTheme;
 		}
 
 		protected virtual Window CreateWindow(IActivationState? activationState)

src/Controls/src/Core/HandlerImpl/Window/Window.Impl.cs

@@ -5,6 +5,7 @@
 using System.Linq;
 using System.Runtime.CompilerServices;
 using System.Threading.Tasks;
+using Microsoft.Maui.ApplicationModel;
 using Microsoft.Maui.Controls.Internals;
 using Microsoft.Maui.Controls.Platform;
 using Microsoft.Maui.Graphics;
@@ -561,7 +562,8 @@ private protected override void OnHandlerChangingCore(HandlerChangingEventArgs a
 
 			if (FlowDirection == FlowDirection.MatchParent && mauiContext != null)
 			{
-				FlowController.EffectiveFlowDirection = mauiContext.GetFlowDirection().ToEffectiveFlowDirection(true);
+				var flowDirection = AppInfo.Current.RequestedLayoutDirection.ToFlowDirection();
+				FlowController.EffectiveFlowDirection = flowDirection.ToEffectiveFlowDirection(true);
 			}
 		}
 

src/Controls/tests/Core.UnitTests/MockPlatformServices.cs

@@ -84,6 +84,9 @@ public class MockApplication : Application
 		public MockApplication()
 		{
 		}
+
+		public void NotifyThemeChanged() =>
+			(this as IApplication).ThemeChanged();
 	}
 
 	internal class MockTicker : Ticker

src/Controls/tests/Xaml.UnitTests/OnAppThemeTests.cs

@@ -10,13 +10,14 @@ namespace Microsoft.Maui.Controls.Xaml.UnitTests
 	public class OnAppThemeTests : BaseTestFixture
 	{
 		MockAppInfo mockAppInfo;
+		MockApplication mockApp;
 
 		[SetUp]
 		public override void Setup()
 		{
 			base.Setup();
 			AppInfo.SetCurrent(mockAppInfo = new MockAppInfo());
-			Application.Current = new MockApplication();
+			Application.Current = mockApp = new MockApplication();
 		}
 
 		[TearDown]
@@ -36,11 +37,11 @@ public void OnAppThemeExtensionLightDarkColor()
 			xmlns:x=""http://schemas.microsoft.com/winfx/2009/xaml"" TextColor=""{AppThemeBinding Light = Green, Dark = Red}
 			"">This text is green or red depending on Light (or default) or Dark</Label>";
 
-			mockAppInfo.RequestedTheme = AppTheme.Light;
+			SetAppTheme(AppTheme.Light);
 			var label = new Label().LoadFromXaml(xaml);
 			Assert.AreEqual(Colors.Green, label.TextColor);
 
-			mockAppInfo.RequestedTheme = AppTheme.Dark;
+			SetAppTheme(AppTheme.Dark);
 			label = new Label().LoadFromXaml(xaml);
 			Assert.AreEqual(Colors.Red, label.TextColor);
 		}
@@ -58,11 +59,11 @@ public void OnAppThemeLightDarkColor()
 				</Label.TextColor>
 			</Label> ";
 
-			mockAppInfo.RequestedTheme = AppTheme.Light;
+			SetAppTheme(AppTheme.Light);
 			var label = new Label().LoadFromXaml(xaml);
 			Assert.AreEqual(Colors.Green, label.TextColor);
 
-			mockAppInfo.RequestedTheme = AppTheme.Dark;
+			SetAppTheme(AppTheme.Dark);
 			label = new Label().LoadFromXaml(xaml);
 			Assert.AreEqual(Colors.Red, label.TextColor);
 		}
@@ -80,7 +81,7 @@ public void OnAppThemeUnspecifiedThemeDefaultsToLightColor()
 				</Label.TextColor>
 			</Label> ";
 
-			mockAppInfo.RequestedTheme = AppTheme.Unspecified;
+			SetAppTheme(AppTheme.Unspecified);
 			var label = new Label().LoadFromXaml(xaml);
 			Assert.AreEqual(Colors.Green, label.TextColor);
 		}
@@ -98,7 +99,7 @@ public void OnAppThemeUnspecifiedLightColorDefaultsToDefault()
 				</Label.TextColor>
 			</Label> ";
 
-			mockAppInfo.RequestedTheme = AppTheme.Light;
+			SetAppTheme(AppTheme.Light);
 			var label = new Label().LoadFromXaml(xaml);
 			Assert.AreEqual(Colors.Green, label.TextColor);
 		}
@@ -116,11 +117,11 @@ public void AppThemeColorLightDark()
 				</Label.TextColor>
 			</Label> ";
 
-			mockAppInfo.RequestedTheme = AppTheme.Light;
+			SetAppTheme(AppTheme.Light);
 			var label = new Label().LoadFromXaml(xaml);
 			Assert.AreEqual(Colors.Green, label.TextColor);
 
-			mockAppInfo.RequestedTheme = AppTheme.Dark;
+			SetAppTheme(AppTheme.Dark);
 			label = new Label().LoadFromXaml(xaml);
 			Assert.AreEqual(Colors.Red, label.TextColor);
 		}
@@ -138,7 +139,7 @@ public void AppThemeColorUnspecifiedThemeDefaultsToLightColor()
 				</Label.TextColor>
 			</Label> ";
 
-			mockAppInfo.RequestedTheme = AppTheme.Unspecified;
+			SetAppTheme(AppTheme.Unspecified);
 			var label = new Label().LoadFromXaml(xaml);
 			Assert.AreEqual(Colors.Green, label.TextColor);
 		}
@@ -156,9 +157,15 @@ public void AppThemeColorUnspecifiedLightColorDefaultsToDefault()
 				</Label.TextColor>
 			</Label> ";
 
-			mockAppInfo.RequestedTheme = AppTheme.Unspecified;
+			SetAppTheme(AppTheme.Unspecified);
 			var label = new Label().LoadFromXaml(xaml);
 			Assert.AreEqual(Colors.Green, label.TextColor);
 		}
+
+		void SetAppTheme(AppTheme theme)
+		{
+			mockAppInfo.RequestedTheme = theme;
+			mockApp.NotifyThemeChanged();
+		}
 	}
 }

src/Core/src/MauiContextExtensions.cs

@@ -75,15 +75,5 @@ public static void InitializeScopedServices(this IMauiContext scopedContext)
 			foreach (var service in scopedServices)
 				service.Initialize(scopedContext.Services);
 		}
-
-		public static FlowDirection GetFlowDirection(this IMauiContext mauiContext)
-		{
-			var appInfo = AppInfo.Current;
-
-			if (appInfo.RequestedLayoutDirection == LayoutDirection.RightToLeft)
-				return FlowDirection.RightToLeft;
-
-			return FlowDirection.LeftToRight;
-		}
 	}
 }

src/Essentials/src/AppInfo/AppInfo.android.cs

@@ -16,8 +16,6 @@ class AppInfoImplementation : IAppInfo
 #pragma warning disable CS0618, CA1416, CA1422 // Deprecated in API 33: https://developer.android.com/reference/android/content/pm/PackageManager#getPackageInfo(java.lang.String,%20int)
 		static readonly Lazy<PackageInfo> _packageInfo = new Lazy<PackageInfo>(() => Application.Context.PackageManager.GetPackageInfo(_packageName.Value, PackageInfoFlags.MetaData));
 #pragma warning restore CS0618, CA1416, CA1422
-		static readonly Lazy<AppTheme> _requestedTheme = new Lazy<AppTheme>(GetRequestedTheme);
-		static readonly Lazy<LayoutDirection> _layoutDirection = new Lazy<LayoutDirection>(GetLayoutDirection);
 
 		public string PackageName => _packageName.Value;
 
@@ -44,14 +42,21 @@ public void ShowSettingsUI()
 			context.StartActivity(settingsIntent);
 		}
 
-		static AppTheme GetRequestedTheme() => (Application.Context.Resources.Configuration.UiMode & UiMode.NightMask) switch
+		static AppTheme GetRequestedTheme()
 		{
-			UiMode.NightYes => AppTheme.Dark,
-			UiMode.NightNo => AppTheme.Light,
-			_ => AppTheme.Unspecified
-		};
+			var config = Application.Context.Resources?.Configuration;
+			if (config == null)
+				return AppTheme.Unspecified;
+
+			return (config.UiMode & UiMode.NightMask) switch
+			{
+				UiMode.NightYes => AppTheme.Dark,
+				UiMode.NightNo => AppTheme.Light,
+				_ => AppTheme.Unspecified
+			};
+		}
 
-		public AppTheme RequestedTheme => _requestedTheme.Value;
+		public AppTheme RequestedTheme => GetRequestedTheme();
 
 		public AppPackagingModel PackagingModel => AppPackagingModel.Packaged;
 
@@ -61,10 +66,11 @@ static LayoutDirection GetLayoutDirection()
 			if (config == null)
 				return LayoutDirection.Unknown;
 
-			return (config.LayoutDirection == Android.Views.LayoutDirection.Rtl) ? LayoutDirection.RightToLeft :
-				LayoutDirection.LeftToRight;
+			return (config.LayoutDirection == Android.Views.LayoutDirection.Rtl)
+				? LayoutDirection.RightToLeft
+				: LayoutDirection.LeftToRight;
 		}
 
-		public LayoutDirection RequestedLayoutDirection => _layoutDirection.Value;
+		public LayoutDirection RequestedLayoutDirection => GetLayoutDirection();
 	}
 }