Windows FlowDirection (#4936)

* RTL_Window

* - setup flow direction handlers

* - set flow directions from other platforms

* - RTL Reading check

* - add tests

* - remove setdevice

* - remove setFlowDirection

* - RTL

* - additional RTL settings

* - change to current culture

* - move flowdirection check to Essentials

* - fix tests

* - if/def device for now

* - fix flowdirection

* - change NS implementation to return unknown

* - fix mock platform services

Co-authored-by: Matthew Leibowitz <mattleibow@live.com>

src/Compatibility/Core/src/Android/Forms.cs

@@ -236,8 +236,6 @@ static void SetupInit(
 
 			Profile.FramePartition("Epilog");
 
-			Device.SetFlowDirection(activity.Resources.Configuration.LayoutDirection.ToFlowDirection());
-
 			if (ExpressionSearch.Default == null)
 				ExpressionSearch.Default = new AndroidExpressionSearch();
 

src/Compatibility/Core/src/Windows/Forms.cs

@@ -50,8 +50,6 @@ static void SetupInit(
 			var accent = (WSolidColorBrush)Microsoft.UI.Xaml.Application.Current.Resources["SystemColorControlAccentBrush"];
 			KnownColor.SetAccent(accent.ToColor());
 
-			Device.SetFlowDirection(mauiContext.GetFlowDirection());
-
 			ExpressionSearch.Default = new WindowsExpressionSearch();
 
 			Registrar.ExtraAssemblies = rendererAssemblies?.ToArray();

src/Compatibility/Core/src/iOS/Forms.cs

@@ -145,34 +145,6 @@ static void SetupInit(IMauiContext context, InitializationOptions? maybeOptions
 
 			Application.AccentColor = Color.FromRgba(50, 79, 133, 255);
 
-#if __MOBILE__
-			Device.SetFlowDirection(UIApplication.SharedApplication.UserInterfaceLayoutDirection.ToFlowDirection());
-#else
-			if (!IsInitialized)
-			{
-				// Only need to do this once
-				// Subscribe to notifications in OS Theme changes
-				NSDistributedNotificationCenter.GetDefaultCenter().AddObserver((NSString)"AppleInterfaceThemeChangedNotification", (n) =>
-				{
-					var interfaceStyle = NSUserDefaults.StandardUserDefaults.StringForKey("AppleInterfaceStyle");
-
-					var aquaAppearance = NSAppearance.GetAppearance(interfaceStyle == "Dark" ? NSAppearance.NameDarkAqua : NSAppearance.NameAqua);
-					NSApplication.SharedApplication.Appearance = aquaAppearance;
-
-					Application.Current?.TriggerThemeChanged(new AppThemeChangedEventArgs(interfaceStyle == "Dark" ? AppTheme.Dark : AppTheme.Light));
-				});
-			}
-
-			Device.SetFlowDirection(NSApplication.SharedApplication.UserInterfaceLayoutDirection.ToFlowDirection());
-
-			if (IsMojaveOrNewer)
-			{
-				var interfaceStyle = NSUserDefaults.StandardUserDefaults.StringForKey("AppleInterfaceStyle");
-				var aquaAppearance = NSAppearance.GetAppearance(interfaceStyle == "Dark" ? NSAppearance.NameDarkAqua : NSAppearance.NameAqua);
-				NSApplication.SharedApplication.Appearance = aquaAppearance;
-			}
-#endif
-
 			Device.DefaultRendererAssembly = typeof(Forms).Assembly;
 
 			if (maybeOptions?.Flags.HasFlag(InitializationFlags.SkipRenderers) != true)

src/Controls/docs/Microsoft.Maui.Controls/Device.xml

@@ -692,38 +692,6 @@ button.HeightRequest = Device.OnPlatform (20,30,30);
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
-    <Member MemberName="SetFlowDirection">
-      <MemberSignature Language="C#" Value="public static void SetFlowDirection (Microsoft.Maui.Controls.FlowDirection value);" />
-      <MemberSignature Language="ILAsm" Value=".method public static hidebysig void SetFlowDirection(valuetype Microsoft.Maui.Controls.FlowDirection value) cil managed" />
-      <MemberSignature Language="DocId" Value="M:Microsoft.Maui.Controls.Device.SetFlowDirection(Microsoft.Maui.Controls.FlowDirection)" />
-      <MemberSignature Language="F#" Value="static member SetFlowDirection : Microsoft.Maui.Controls.FlowDirection -&gt; unit" Usage="Microsoft.Maui.Controls.Device.SetFlowDirection value" />
-      <MemberType>Method</MemberType>
-      <AssemblyInfo>
-        <AssemblyName>Microsoft.Maui.Controls.Core</AssemblyName>
-        <AssemblyVersion>0.0.0.0</AssemblyVersion>
-        <AssemblyVersion>2.0.0.0</AssemblyVersion>
-      </AssemblyInfo>
-      <Attributes>
-        <Attribute>
-          <AttributeName>System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)</AttributeName>
-        </Attribute>
-      </Attributes>
-      <ReturnValue>
-        <ReturnType>System.Void</ReturnType>
-      </ReturnValue>
-      <Parameters>
-        <Parameter Name="value" Type="Microsoft.Maui.Controls.FlowDirection" />
-      </Parameters>
-      <Docs>
-        <param name="value">The new flow direction value to set.</param>
-        <summary>Sets the flow direction on the device.</summary>
-        <remarks>
-          <para>The following contains a few important points about flow direction from <format type="text/html"><a href="https://docs.microsoft.com/xamarin/xamarin-forms/app-fundamentals/localization/rtl">Right-to-Left Localization</a></format>. Developers should consult that document for more information about limitations of right-to-left support, and for requirements to implement right-to-left support on various target platforms.</para>
-          <para>The default value of <see cref="T:Microsoft.Maui.Controls.FlowDirection" /> for a visual element that has no parent is <see cref="F:Microsoft.Maui.Controls.FlowDirection.LeftToRight" />, even on platforms where <see cref="P:Microsoft.Maui.Controls.Device.FlowDirection" /> is <see cref="F:Microsoft.Maui.Controls.FlowDirection.RightToLeft" />. Therefore, developers must deliberately opt in to right-to-left layout. Developers can choose right-to-left layout by setting the <see cref="P:Microsoft.Maui.Controls.VisualElement.FlowDirection" /> property of the root element to <see cref="F:Microsoft.Maui.Controls.FlowDirection.RightToLeft" /> to chosse right-to-left layout, or to <see cref="F:Microsoft.Maui.Controls.FlowDirection.MatchParent" /> to match the device layout.</para>
-          <para>All <see cref="T:Microsoft.Maui.Controls.VisualElement" />s that have a parent default to <see cref="F:Microsoft.Maui.Controls.FlowDirection.MatchParent" />.</para>
-        </remarks>
-      </Docs>
-    </Member>
     <Member MemberName="StartTimer">
       <MemberSignature Language="C#" Value="public static void StartTimer (TimeSpan interval, Func&lt;bool&gt; callback);" />
       <MemberSignature Language="ILAsm" Value=".method public static hidebysig void StartTimer(valuetype System.TimeSpan interval, class System.Func`1&lt;bool&gt; callback) cil managed" />

src/Controls/src/Core/Device.cs

@@ -56,11 +56,16 @@ public static TargetIdiom Idiom
 		/// <include file="../../docs/Microsoft.Maui.Controls/Device.xml" path="//Member[@MemberName='RuntimePlatform']/Docs" />
 		public static string RuntimePlatform => DeviceInfo.Platform.ToString();
 
-		/// <include file="../../docs/Microsoft.Maui.Controls/Device.xml" path="//Member[@MemberName='SetFlowDirection']/Docs" />
-		[EditorBrowsable(EditorBrowsableState.Never)]
-		public static void SetFlowDirection(FlowDirection value) => FlowDirection = value;
+		// [Obsolete]
 		/// <include file="../../docs/Microsoft.Maui.Controls/Device.xml" path="//Member[@MemberName='FlowDirection']/Docs" />
-		public static FlowDirection FlowDirection { get; internal set; }
+		public static FlowDirection FlowDirection
+		{
+			get
+			{
+				return AppInfo.RequestedLayoutDirection == LayoutDirection.RightToLeft
+					? FlowDirection.RightToLeft : FlowDirection.LeftToRight;
+			}
+		}
 
 		//[Obsolete("Use BindableObject.Dispatcher instead.")]
 		/// <include file="../../docs/Microsoft.Maui.Controls/Device.xml" path="//Member[@MemberName='IsInvokeRequired']/Docs" />

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

@@ -12,18 +12,17 @@
 namespace Microsoft.Maui.Controls
 {
 	[ContentProperty(nameof(Page))]
-	public partial class Window : NavigableElement, IWindow, IVisualTreeElement, IToolbarElement, IMenuBarElement
+	public partial class Window : NavigableElement, IWindow, IVisualTreeElement, IToolbarElement, IMenuBarElement, IFlowDirectionController
 	{
 		public static readonly BindableProperty TitleProperty = BindableProperty.Create(
 			nameof(Title), typeof(string), typeof(Window), default(string?));
 
-		public static readonly BindableProperty MenuBarProperty = BindableProperty.Create(
-			nameof(MenuBar), typeof(MenuBar), typeof(Window), default(MenuBar));
-
 		public static readonly BindableProperty PageProperty = BindableProperty.Create(
 			nameof(Page), typeof(Page), typeof(Window), default(Page?),
 			propertyChanged: OnPageChanged);
 
+		public static readonly BindableProperty FlowDirectionProperty = BindableProperty.Create(nameof(FlowDirection), typeof(FlowDirection), typeof(Window), FlowDirection.MatchParent, propertyChanging: FlowDirectionChanging, propertyChanged: FlowDirectionChanged);
+
 		HashSet<IWindowOverlay> _overlays = new HashSet<IWindowOverlay>();
 		ReadOnlyCollection<Element>? _logicalChildren;
 		List<IVisualTreeElement> _visualChildren;
@@ -149,6 +148,56 @@ public bool RemoveOverlay(IWindowOverlay overlay)
 		internal IMauiContext MauiContext =>
 			Handler?.MauiContext ?? throw new InvalidOperationException("MauiContext is null.");
 
+		IFlowDirectionController FlowController => this;
+
+		public FlowDirection FlowDirection
+		{
+			get { return (FlowDirection)GetValue(FlowDirectionProperty); }
+			set { SetValue(FlowDirectionProperty, value); }
+		}
+
+		EffectiveFlowDirection _effectiveFlowDirection = default(EffectiveFlowDirection);
+		EffectiveFlowDirection IFlowDirectionController.EffectiveFlowDirection
+		{
+			get => _effectiveFlowDirection;
+			set => SetEffectiveFlowDirection(value, true);
+		}
+
+		double IFlowDirectionController.Width => (Page as VisualElement)?.Width ?? 0;
+
+		void SetEffectiveFlowDirection(EffectiveFlowDirection value, bool fireFlowDirectionPropertyChanged)
+		{
+			if (value == _effectiveFlowDirection)
+				return;
+
+			_effectiveFlowDirection = value;
+
+			if (fireFlowDirectionPropertyChanged)
+				OnPropertyChanged(FlowDirectionProperty.PropertyName);
+
+		}
+
+		static void FlowDirectionChanging(BindableObject bindable, object oldValue, object newValue)
+		{
+			var self = (IFlowDirectionController)bindable;
+
+			if (self.EffectiveFlowDirection.IsExplicit() && oldValue == newValue)
+				return;
+
+			var newFlowDirection = ((FlowDirection)newValue).ToEffectiveFlowDirection(isExplicit: true);
+			self.EffectiveFlowDirection = newFlowDirection;
+		}
+
+		static void FlowDirectionChanged(BindableObject bindable, object oldValue, object newValue)
+		{
+			PropertyPropagationExtensions.PropagatePropertyChanged(
+				FlowDirectionProperty.PropertyName,
+				(Element)bindable,
+				((IElementController)bindable).LogicalChildren);
+		}
+
+		bool IFlowDirectionController.ApplyEffectiveFlowDirectionToChildContainer => true;
+
 		IView IWindow.Content =>
 			Page ?? throw new InvalidOperationException("No page was set on the window.");
 
@@ -277,6 +326,36 @@ void IWindow.Backgrounding(IPersistedState state)
 			OnBackgrounding(state);
 		}
 
+		FlowDirection IWindow.FlowDirection
+		{
+			get
+			{
+				// If the user has set the root page to be RTL
+				// Then we want the window to also reflect RTL
+				// We don't want to force the user to reach into the window
+				// in order to enable RTL Window features on WinUI
+				if (FlowDirection == FlowDirection.MatchParent &&
+					Page is IFlowDirectionController controller &&
+					controller.EffectiveFlowDirection.IsExplicit())
+				{
+					return controller.EffectiveFlowDirection.ToFlowDirection();
+				}
+
+				return _effectiveFlowDirection.ToFlowDirection();
+			}
+		}
+
+		private protected override void OnHandlerChangingCore(HandlerChangingEventArgs args)
+		{
+			base.OnHandlerChangingCore(args);
+			var mauiContext = args?.NewHandler?.MauiContext;
+
+			if (FlowDirection == FlowDirection.MatchParent && mauiContext != null)
+			{
+				FlowController.EffectiveFlowDirection = mauiContext.GetFlowDirection().ToEffectiveFlowDirection(true);
+			}
+		}
+
 		// Currently this returns MainPage + ModalStack
 		// Depending on how we want this to show up inside LVT
 		// we might want to change this to only return the currently visible page
@@ -315,6 +394,8 @@ static void OnPageChanged(BindableObject bindable, object oldValue, object newVa
 					OnPageHandlerChanged(newPage, EventArgs.Empty);
 			}
 
+			window?.Handler?.UpdateValue(nameof(IWindow.FlowDirection));
+
 			void OnPageHandlerChanged(object? sender, EventArgs e)
 			{
 				window.ModalNavigationManager.PageAttachedHandler();

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

@@ -6,12 +6,6 @@ namespace Microsoft.Maui.Controls.Core.UnitTests
 	[TestFixture]
 	public class EffectiveFlowDirectionExtensions : BaseTestFixture
 	{
-		public override void Setup()
-		{
-			base.Setup();
-			Device.FlowDirection = FlowDirection.LeftToRight;
-		}
-
 		[Test]
 		public void LeftToRightImplicit()
 		{

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

@@ -527,14 +527,6 @@ public void ShellPropagatesRightToLeftChangetoNewElements()
 			Assert.IsTrue(stacklayoutVisualController.IsRightToLeft(), "EffectiveFlowDirection should be RightToLeft");
 		}
 
-
-		[SetUp]
-		public override void Setup()
-		{
-			base.Setup();
-			Device.FlowDirection = FlowDirection.LeftToRight;
-		}
-
 		static void AddExplicitLTRToScrollView(ScrollView parent, View child)
 		{
 			parent.Content = child;

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

@@ -254,6 +254,8 @@ class MockAppInfo : IAppInfo
 
 		public string BuildString { get; set; }
 
+		public LayoutDirection RequestedLayoutDirection { get; set; }
+
 		public void ShowSettingsUI()
 		{
 		}

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

@@ -6,6 +6,35 @@ namespace Microsoft.Maui.Controls.Core.UnitTests
 	[TestFixture]
 	public class WindowsTests : BaseTestFixture
 	{
+		[Test]
+		public void ContentPageFlowDirectionSetsOnIWindow()
+		{
+			var app = new TestApp();
+			var window = app.CreateWindow();
+			window.Page.FlowDirection = FlowDirection.RightToLeft;
+
+			Assert.IsTrue((window as IWindow)
+				.FlowDirection == FlowDirection.RightToLeft);
+		}
+
+		[Test]
+		public void WindowFlowDirectionSetsOnPage()
+		{
+			var app = new TestApp();
+			var window = app.CreateWindow();
+			window.FlowDirection = FlowDirection.RightToLeft;
+
+			Assert.IsTrue((window.Page as IFlowDirectionController)
+				.EffectiveFlowDirection
+				.IsRightToLeft());
+
+			window.Page = new ContentPage();
+
+			Assert.IsTrue((window.Page as IFlowDirectionController)
+				.EffectiveFlowDirection
+				.IsRightToLeft());
+		}
+
 		[Test]
 		public void AddWindow()
 		{

src/Core/src/Core/IWindow.cs

@@ -76,5 +76,7 @@ public interface IWindow : ITitledElement
 		/// </summary>
 		/// <returns>Whether or not the back navigation was handled.</returns>
 		bool BackButtonClicked();
+
+		FlowDirection FlowDirection { get; }
 	}
 }

src/Core/src/Handlers/Window/WindowHandler.Windows.cs

@@ -27,10 +27,10 @@ protected override void ConnectHandler(UI.Xaml.Window platformView)
 		}
 
 		protected override void DisconnectHandler(UI.Xaml.Window platformView)
-		{			
+		{
 			MauiContext
 				?.GetNavigationRootManager()
-				?.Disconnect();			
+				?.Disconnect();
 
 			_rootPanel?.Children?.Clear();
 			platformView.Content = null;
@@ -73,5 +73,21 @@ public static void MapMenuBar(IWindowHandler handler, IWindow view)
 				windowManager.SetMenuBar(mb.MenuBar);
 			}
 		}
+
+		public static void MapFlowDirection(IWindowHandler handler, IWindow view)
+		{
+			var WindowHandle = handler.PlatformView.GetWindowHandle();
+
+			// Retrieve current extended style
+			var extended_style = PlatformMethods.GetWindowLongPtr(WindowHandle, PlatformMethods.WindowLongFlags.GWL_EXSTYLE);
+			long updated_style;
+			if (view.FlowDirection == FlowDirection.RightToLeft)
+				updated_style = extended_style | (long)PlatformMethods.ExtendedWindowStyles.WS_EX_LAYOUTRTL;
+			else
+				updated_style = extended_style & ~((long)PlatformMethods.ExtendedWindowStyles.WS_EX_LAYOUTRTL);
+
+			if (updated_style != extended_style)
+				PlatformMethods.SetWindowLongPtr(WindowHandle, PlatformMethods.WindowLongFlags.GWL_EXSTYLE, updated_style);
+		}
 	}
 }

src/Core/src/Handlers/Window/WindowHandler.cs

@@ -18,9 +18,12 @@ public partial class WindowHandler : IWindowHandler
 			[nameof(IWindow.Content)] = MapContent,
 #if ANDROID || WINDOWS
 			[nameof(IToolbarElement.Toolbar)] = MapToolbar,
-#endif	
+#endif
 #if WINDOWS || IOS
 			[nameof(IMenuBarElement.MenuBar)] = MapMenuBar,
+#endif
+#if WINDOWS
+			[nameof(IWindow.FlowDirection)] = MapFlowDirection,
 #endif
 		};
 

src/Core/src/MauiContextExtensions.cs

@@ -1,6 +1,7 @@
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Maui.Animations;
 using Microsoft.Maui.Dispatching;
+using Microsoft.Maui.Essentials;
 using Microsoft.Maui.Hosting;
 
 #if WINDOWS
@@ -67,5 +68,15 @@ 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;
+		}
 	}
 }