Windows message loop manager

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

@@ -1,5 +1,6 @@
 using System;
 using Microsoft.UI.Xaml.Controls;
+using Microsoft.Maui.ApplicationModel;
 
 namespace Microsoft.Maui.Handlers
 {

src/Core/src/Hosting/EssentialsMauiAppBuilderExtensions.cs

@@ -62,10 +62,6 @@ internal static MauiAppBuilder UseEssentials(this MauiAppBuilder builder)
 					}));
 #elif WINDOWS
 				life.AddWindows(windows => windows
-					.OnPlatformMessage((window, args) =>
-					{
-						ApplicationModel.Platform.OnWindowMessage(args.Hwnd, args.MessageId, args.WParam, args.LParam);
-					})
 					.OnActivated((window, args) =>
 					{
 						ApplicationModel.Platform.OnActivated(window, args);

src/Core/src/Platform/Windows/MauiWinUIWindow.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Runtime.InteropServices;
+using Microsoft.Maui.ApplicationModel;
 using Microsoft.Maui.Devices;
 using Microsoft.Maui.LifecycleEvents;
 using Microsoft.UI;
@@ -10,11 +11,15 @@ namespace Microsoft.Maui
 {
 	public class MauiWinUIWindow : UI.Xaml.Window
 	{
+		readonly WindowMessageManager _windowManager;
+
 		IntPtr _windowIcon;
 		bool _enableResumeEvent;
 
 		public MauiWinUIWindow()
 		{
+			_windowManager = WindowMessageManager.Get(this);
+
 			Activated += OnActivated;
 			Closed += OnClosedPrivate;
 			VisibilityChanged += OnVisibilityChanged;
@@ -62,58 +67,37 @@ protected virtual void OnVisibilityChanged(object sender, UI.Xaml.WindowVisibili
 			MauiWinUIApplication.Current.Services?.InvokeLifecycleEvents<WindowsLifecycle.OnVisibilityChanged>(del => del(this, args));
 		}
 
-		#region Platform Window
-
-		IntPtr _hwnd = IntPtr.Zero;
-
-		/// <summary>
-		/// Returns a pointer to the underlying platform window handle (hWnd).
-		/// </summary>
-		public IntPtr WindowHandle
-		{
-			get
-			{
-				if (_hwnd == IntPtr.Zero)
-					_hwnd = this.GetWindowHandle();
-				return _hwnd;
-			}
-		}
-
-		PlatformMethods.WindowProc? newWndProc = null;
-		IntPtr oldWndProc = IntPtr.Zero;
+		public IntPtr WindowHandle => _windowManager.WindowHandle;
 
 		void SubClassingWin32()
 		{
 			MauiWinUIApplication.Current.Services?.InvokeLifecycleEvents<WindowsLifecycle.OnPlatformWindowSubclassed>(
 				del => del(this, new WindowsPlatformWindowSubclassedEventArgs(WindowHandle)));
 
-			newWndProc = new PlatformMethods.WindowProc(NewWindowProc);
-			oldWndProc = PlatformMethods.SetWindowLongPtr(WindowHandle, PlatformMethods.WindowLongFlags.GWL_WNDPROC, newWndProc);
+			_windowManager.WindowMessage += OnWindowMessage;
 
-			IntPtr NewWindowProc(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam)
+			void OnWindowMessage(object? sender, WindowMessageEventArgs e)
 			{
-				if (msg == WindowsPlatformMessageIds.WM_SETTINGCHANGE || msg == WindowsPlatformMessageIds.WM_THEMECHANGE)
+				if (e.MessageId == PlatformMethods.MessageIds.WM_SETTINGCHANGE ||
+					e.MessageId == PlatformMethods.MessageIds.WM_THEMECHANGE)
+				{
 					MauiWinUIApplication.Current.Application?.ThemeChanged();
-
-				if (msg == WindowsPlatformMessageIds.WM_DPICHANGED)
+				}
+				else if (e.MessageId == PlatformMethods.MessageIds.WM_DPICHANGED)
 				{
-					var dpiX = (short)(long)wParam;
-					var dpiY = (short)((long)wParam >> 16);
+					var dpiX = (short)(long)e.WParam;
+					var dpiY = (short)((long)e.WParam >> 16);
 
 					var window = this.GetWindow();
 					if (window is not null)
 						window.DisplayDensityChanged(dpiX / DeviceDisplay.BaseLogicalDpi);
 				}
 
 				MauiWinUIApplication.Current.Services?.InvokeLifecycleEvents<WindowsLifecycle.OnPlatformMessage>(
-					m => m.Invoke(this, new WindowsPlatformMessageEventArgs(hWnd, msg, wParam, lParam)));
-
-				return PlatformMethods.CallWindowProc(oldWndProc, hWnd, msg, wParam, lParam);
+					m => m.Invoke(this, new WindowsPlatformMessageEventArgs(e.Hwnd, e.MessageId, e.WParam, e.LParam)));
 			}
 		}
 
-		#endregion
-
 		/// <summary>
 		/// Default the Window Icon to the icon stored in the .exe, if any.
 		/// 

src/Core/src/Platform/Windows/NavigationRootManager.cs

@@ -1,4 +1,5 @@
 using System;
+using Microsoft.Maui.ApplicationModel;
 using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Controls;
 using Microsoft.UI.Xaml.Media;

src/Core/src/Platform/Windows/WindowExtensions.cs

@@ -1,4 +1,5 @@
 using System;
+using Microsoft.Maui.ApplicationModel;
 using Microsoft.Maui.Devices;
 using System.Threading.Tasks;
 using Microsoft.Maui.Media;

src/Essentials/src/AppInfo/AppInfo.uwp.cs

@@ -1,13 +1,9 @@
 using System;
-using System.Globalization;
-using Windows.ApplicationModel;
 using System.Diagnostics;
+using System.Globalization;
 using System.Reflection;
-#if WINDOWS
 using Microsoft.UI.Xaml;
-#else
-using Windows.UI.Xaml;
-#endif
+using Windows.ApplicationModel;
 
 namespace Microsoft.Maui.ApplicationModel
 {
@@ -19,11 +15,13 @@ class AppInfoImplementation : IAppInfo
 
 		ApplicationTheme? _applicationTheme;
 
+		readonly ActiveWindowTracker _activeWindowTracker;
+
 		public AppInfoImplementation()
 		{
-			// TODO: NET7 use new public events
-			if (WindowStateManager.Default is WindowStateManagerImplementation impl)
-				impl.ActiveWindowThemeChanged += OnActiveWindowThemeChanged;
+			_activeWindowTracker = new(WindowStateManager.Default);
+			_activeWindowTracker.Start();
+			_activeWindowTracker.WindowMessage += OnWindowMessage;
 
 			if (MainThread.IsMainThread)
 				OnActiveWindowThemeChanged();
@@ -78,7 +76,14 @@ public AppTheme RequestedTheme
 		public LayoutDirection RequestedLayoutDirection =>
 			CultureInfo.CurrentCulture.TextInfo.IsRightToLeft ? LayoutDirection.RightToLeft : LayoutDirection.LeftToRight;
 
-		void OnActiveWindowThemeChanged(object sender = null, EventArgs e = null)
+		void OnWindowMessage(object sender, WindowMessageEventArgs e)
+		{
+			if (e.MessageId == PlatformMethods.MessageIds.WM_SETTINGCHANGE ||
+				e.MessageId == PlatformMethods.MessageIds.WM_THEMECHANGE)
+				OnActiveWindowThemeChanged();
+		}
+
+		void OnActiveWindowThemeChanged()
 		{
 			if (Application.Current is Application app)
 				_applicationTheme = app.RequestedTheme;

src/Essentials/src/DeviceDisplay/DeviceDisplay.uwp.cs

@@ -11,8 +11,16 @@ namespace Microsoft.Maui.Devices
 	partial class DeviceDisplayImplementation
 	{
 		readonly object locker = new object();
+		readonly ActiveWindowTracker _activeWindowTracker;
+
 		DisplayRequest? displayRequest;
 
+		public DeviceDisplayImplementation()
+		{
+			_activeWindowTracker = new(WindowStateManager.Default);
+			_activeWindowTracker.WindowMessage += OnWindowMessage;
+		}
+
 		protected override bool GetKeepScreenOn()
 		{
 			lock (locker)
@@ -44,8 +52,6 @@ protected override void SetKeepScreenOn(bool keepScreenOn)
 			}
 		}
 
-		AppWindow? _currentAppWindowListeningTo;
-
 		protected override DisplayInfo GetMainDisplayInfo()
 		{
 			if (WindowStateManager.Default.GetActiveAppWindow(false) is not AppWindow appWindow)
@@ -102,47 +108,22 @@ protected override DisplayInfo GetMainDisplayInfo()
 			return null;
 		}
 
-		protected override void StartScreenMetricsListeners()
-		{
-			MainThread.BeginInvokeOnMainThread(() =>
-			{
-				WindowStateManager.Default.ActiveWindowDisplayChanged += OnWindowDisplayChanged;
-				WindowStateManager.Default.ActiveWindowChanged += OnCurrentWindowChanged;
+		protected override void StartScreenMetricsListeners() =>
+			MainThread.BeginInvokeOnMainThread(_activeWindowTracker.Start);
 
-				_currentAppWindowListeningTo = WindowStateManager.Default.GetActiveAppWindow(true)!;
-				_currentAppWindowListeningTo.Changed += OnAppWindowChanged;
-			});
-		}
+		protected override void StopScreenMetricsListeners() =>
+			MainThread.BeginInvokeOnMainThread(_activeWindowTracker.Stop);
 
-		protected override void StopScreenMetricsListeners()
+		// Currently there isn't a way to detect Orientation Changes unless you subclass the WinUI.Window and watch the messages.
+		// This is the "subtlest" way to currently wire this together.
+		// Hopefully there will be a more public API for this down the road so we can just use that directly from Essentials
+		void OnWindowMessage(object? sender, WindowMessageEventArgs e)
 		{
-			MainThread.BeginInvokeOnMainThread(() =>
-			{
-				WindowStateManager.Default.ActiveWindowChanged -= OnCurrentWindowChanged;
-				WindowStateManager.Default.ActiveWindowDisplayChanged -= OnWindowDisplayChanged;
-
-				if (_currentAppWindowListeningTo != null)
-					_currentAppWindowListeningTo.Changed -= OnAppWindowChanged;
-
-				_currentAppWindowListeningTo = null;
-			});
-		}
-
-		void OnCurrentWindowChanged(object? sender, EventArgs e)
-		{
-			if (_currentAppWindowListeningTo != null)
-				_currentAppWindowListeningTo.Changed -= OnAppWindowChanged;
-
-			_currentAppWindowListeningTo = WindowStateManager.Default.GetActiveAppWindow(true)!;
-			_currentAppWindowListeningTo.Changed += OnAppWindowChanged;
+			if (e.MessageId == PlatformMethods.MessageIds.WM_DISPLAYCHANGE ||
+				e.MessageId == PlatformMethods.MessageIds.WM_DPICHANGED)
+				OnMainDisplayInfoChanged();
 		}
 
-		void OnWindowDisplayChanged(object? sender, EventArgs e) =>
-			OnMainDisplayInfoChanged();
-
-		void OnAppWindowChanged(AppWindow sender, AppWindowChangedEventArgs args) =>
-			OnMainDisplayInfoChanged();
-
 		static DisplayRotation CalculateRotation(DisplayOrientations orientation) =>
 			orientation switch
 			{

src/Essentials/src/Platform/ActiveWindowTracker.uwp.cs

@@ -0,0 +1,58 @@
+#nullable enable
+using System;
+
+namespace Microsoft.Maui.ApplicationModel
+{
+	class ActiveWindowTracker
+	{
+		readonly IWindowStateManager _windowStateManager;
+
+		WindowMessageManager? _currentWindowManager;
+
+		public ActiveWindowTracker(IWindowStateManager windowStateManager)
+		{
+			_windowStateManager = windowStateManager;
+		}
+
+		public event EventHandler<WindowMessageEventArgs>? WindowMessage;
+
+		public void Start()
+		{
+			var window = _windowStateManager.GetActiveWindow();
+			OnActiveWindowChanged(window);
+
+			_windowStateManager.ActiveWindowChanged += OnActiveWindowChanged;
+		}
+
+		public void Stop()
+		{
+			OnActiveWindowChanged(null);
+
+			_windowStateManager.ActiveWindowChanged -= OnActiveWindowChanged;
+		}
+
+		void OnActiveWindowChanged(object? sender, EventArgs e)
+		{
+			var window = _windowStateManager?.GetActiveWindow();
+			OnActiveWindowChanged(window);
+		}
+
+		void OnActiveWindowChanged(UI.Xaml.Window? window)
+		{
+			if (_currentWindowManager is not null)
+			{
+				_currentWindowManager.WindowMessage -= OnWindowMessage;
+				_currentWindowManager = null;
+			}
+
+			if (window is not null)
+			{
+				_currentWindowManager = WindowMessageManager.Get(window);
+				_currentWindowManager.WindowMessage += OnWindowMessage;
+			}
+		}
+
+		void OnWindowMessage(object? sender, WindowMessageEventArgs e) =>
+			WindowMessage?.Invoke(sender, e);
+	}
+}

src/Essentials/src/Platform/Platform.shared.cs

@@ -82,9 +82,6 @@ public static void OnLaunched(UI.Xaml.LaunchActivatedEventArgs e) =>
 		public static void OnActivated(UI.Xaml.Window window, UI.Xaml.WindowActivatedEventArgs args) =>
 			WindowStateManager.Default.OnActivated(window, args);
 
-		public static void OnWindowMessage(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam) =>
-			WindowStateManager.Default.OnWindowMessage(hWnd, msg, wParam, lParam);
-
 #elif TIZEN
 		public static Tizen.Applications.Package CurrentPackage
 		{