From c867fa2c0eb9230628098e3e92e49f978130068f Mon Sep 17 00:00:00 2001
From: Shane Neuville <shneuvil@microsoft.com>
Date: Tue, 6 Jul 2021 16:34:18 -0500
Subject: [PATCH 1/2] WinUI Modal Navigation

---
 .../Controls.Sample/Pages/Core/ModalPage.xaml |  14 ++
 .../Pages/Core/ModalPage.xaml.cs              |  39 +++++
 .../samples/Controls.Sample/Startup.cs        |   2 +-
 .../src/Core/HandlerImpl/Window.Impl.cs       |  18 +-
 .../src/Core/HandlerImpl/Window.Windows.cs    |  12 ++
 .../ModalNavigationManager.Android.cs}        |   6 +-
 .../ModalNavigationManager.Standard.cs}       |   2 +-
 .../ModalNavigationManager.Windows.cs         | 154 ++++++++++++++++++
 .../ModalNavigationManager.cs}                |   5 +-
 .../ModalNavigationManager.iOS.cs}            |   2 +-
 .../ModalNavigationService.Windows.cs         |  22 ---
 .../{iOS/Extensions => }/PageExtensions.cs    |   1 -
 12 files changed, 237 insertions(+), 40 deletions(-)
 create mode 100644 src/Controls/samples/Controls.Sample/Pages/Core/ModalPage.xaml
 create mode 100644 src/Controls/samples/Controls.Sample/Pages/Core/ModalPage.xaml.cs
 create mode 100644 src/Controls/src/Core/HandlerImpl/Window.Windows.cs
 rename src/Controls/src/Core/Platform/{ModalNavigationService/ModalNavigationService.Android.cs => ModalNavigationManager/ModalNavigationManager.Android.cs} (98%)
 rename src/Controls/src/Core/Platform/{ModalNavigationService/ModalNavigationService.Standard.cs => ModalNavigationManager/ModalNavigationManager.Standard.cs} (88%)
 create mode 100644 src/Controls/src/Core/Platform/ModalNavigationManager/ModalNavigationManager.Windows.cs
 rename src/Controls/src/Core/Platform/{ModalNavigationService/ModalNavigationService.cs => ModalNavigationManager/ModalNavigationManager.cs} (93%)
 rename src/Controls/src/Core/Platform/{ModalNavigationService/ModalNavigationService.iOS.cs => ModalNavigationManager/ModalNavigationManager.iOS.cs} (98%)
 delete mode 100644 src/Controls/src/Core/Platform/ModalNavigationService/ModalNavigationService.Windows.cs
 rename src/Controls/src/Core/Platform/{iOS/Extensions => }/PageExtensions.cs (98%)

diff --git a/src/Controls/samples/Controls.Sample/Pages/Core/ModalPage.xaml b/src/Controls/samples/Controls.Sample/Pages/Core/ModalPage.xaml
new file mode 100644
index 000000000000..a3d7f04a69c0
--- /dev/null
+++ b/src/Controls/samples/Controls.Sample/Pages/Core/ModalPage.xaml
@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<views:BasePage 
+    xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+    x:Class="Maui.Controls.Sample.Pages.ModalPage"
+    xmlns:views="clr-namespace:Maui.Controls.Sample.Pages.Base">
+    <views:BasePage.Content>
+        <StackLayout
+            Margin="12">
+            <Button Clicked="PushModalClicked" Text="Push Modal Page" />
+            <Button x:Name="PushModal" Clicked="PopModalClicked" Text="Pop Modal Page" />
+        </StackLayout>
+    </views:BasePage.Content>
+</views:BasePage>
\ No newline at end of file
diff --git a/src/Controls/samples/Controls.Sample/Pages/Core/ModalPage.xaml.cs b/src/Controls/samples/Controls.Sample/Pages/Core/ModalPage.xaml.cs
new file mode 100644
index 000000000000..bc1bfc67f6bf
--- /dev/null
+++ b/src/Controls/samples/Controls.Sample/Pages/Core/ModalPage.xaml.cs
@@ -0,0 +1,39 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.Maui.Controls;
+using Microsoft.Maui.Graphics;
+
+namespace Maui.Controls.Sample.Pages
+{
+	public partial class ModalPage
+	{
+		public ModalPage()
+		{
+			InitializeComponent();
+			BackgroundColor = Colors.Purple;
+		}
+
+		protected override void OnAppearing()
+		{
+			base.OnAppearing();
+			PushModal.IsVisible = Navigation.ModalStack.Count > 0;
+		}
+
+		async void PushModalClicked(object sender, EventArgs e)
+		{
+			await Navigation.PushModalAsync(new ModalPage()
+			{
+				BackgroundColor = 
+					(BackgroundColor == Colors.Purple) ? Colors.Pink : Colors.Purple
+			});
+		}
+
+		async void PopModalClicked(object sender, EventArgs e)
+		{
+			await Navigation.PopModalAsync();
+		}
+	}
+}
\ No newline at end of file
diff --git a/src/Controls/samples/Controls.Sample/Startup.cs b/src/Controls/samples/Controls.Sample/Startup.cs
index 19de29f47875..cd6eae592a9d 100644
--- a/src/Controls/samples/Controls.Sample/Startup.cs
+++ b/src/Controls/samples/Controls.Sample/Startup.cs
@@ -98,7 +98,7 @@ public void Configure(IAppHostBuilder appBuilder)
 						{
 							PageType.Shell => typeof(AppShell),
 #if WINDOWS
-							PageType.Main => typeof(TempPage),
+							PageType.Main => typeof(ModalPage),
 #else
 							PageType.Main => typeof(CustomNavigationPage),
 #endif
diff --git a/src/Controls/src/Core/HandlerImpl/Window.Impl.cs b/src/Controls/src/Core/HandlerImpl/Window.Impl.cs
index 6aa9a68f8e75..57f631697641 100644
--- a/src/Controls/src/Core/HandlerImpl/Window.Impl.cs
+++ b/src/Controls/src/Core/HandlerImpl/Window.Impl.cs
@@ -26,7 +26,7 @@ public partial class Window : NavigableElement, IWindow
 		public Window()
 		{
 			AlertManager = new AlertManager(this);
-			ModalNavigationService = new ModalNavigationService(this);
+			ModalNavigationManager = new ModalNavigationManager(this);
 			Navigation = new NavigationImpl(this);
 
 			InternalChildren.CollectionChanged += OnCollectionChanged;
@@ -75,7 +75,7 @@ protected override void OnPropertyChanged([CallerMemberName] string? propertyNam
 
 		internal AlertManager AlertManager { get; }
 
-		internal ModalNavigationService ModalNavigationService { get; }
+		internal ModalNavigationManager ModalNavigationManager { get; }
 
 		internal IMauiContext MauiContext =>
 			Handler?.MauiContext ?? throw new InvalidOperationException("MauiContext is null.");
@@ -138,7 +138,7 @@ static void OnPageChanged(BindableObject bindable, object oldValue, object newVa
 				newPage.NavigationProxy.Inner = window.NavigationProxy;
 			}
 
-			window.ModalNavigationService.SettingNewPage();
+			window.ModalNavigationManager.SettingNewPage();
 
 			if (newPage != null)
 			{
@@ -148,7 +148,7 @@ static void OnPageChanged(BindableObject bindable, object oldValue, object newVa
 
 			void OnPageAttachedHandler(object? sender, EventArgs e)
 			{
-				window.ModalNavigationService.PageAttachedHandler();
+				window.ModalNavigationManager.PageAttachedHandler();
 				window.AlertManager.Subscribe();
 			}
 
@@ -208,19 +208,19 @@ public NavigationImpl(Window owner)
 
 			protected override IReadOnlyList<Page> GetModalStack()
 			{
-				return _owner.ModalNavigationService.ModalStack;
+				return _owner.ModalNavigationManager.ModalStack;
 			}
 
 			protected override async Task<Page?> OnPopModal(bool animated)
 			{
-				Page modal = _owner.ModalNavigationService.ModalStack[_owner.ModalNavigationService.ModalStack.Count - 1];
+				Page modal = _owner.ModalNavigationManager.ModalStack[_owner.ModalNavigationManager.ModalStack.Count - 1];
 				if (_owner.OnModalPopping(modal))
 				{
 					_owner.OnPopCanceled();
 					return null;
 				}
 
-				Page result = await _owner.ModalNavigationService.PopModalAsync(animated);
+				Page result = await _owner.ModalNavigationManager.PopModalAsync(animated);
 				result.Parent = null;
 				_owner.OnModalPopped(result);
 				return result;
@@ -235,11 +235,11 @@ protected override async Task OnPushModal(Page modal, bool animated)
 				if (modal.NavigationProxy.ModalStack.Count == 0)
 				{
 					modal.NavigationProxy.Inner = this;
-					await _owner.ModalNavigationService.PushModalAsync(modal, animated);
+					await _owner.ModalNavigationManager.PushModalAsync(modal, animated);
 				}
 				else
 				{
-					await _owner.ModalNavigationService.PushModalAsync(modal, animated);
+					await _owner.ModalNavigationManager.PushModalAsync(modal, animated);
 					modal.NavigationProxy.Inner = this;
 				}
 
diff --git a/src/Controls/src/Core/HandlerImpl/Window.Windows.cs b/src/Controls/src/Core/HandlerImpl/Window.Windows.cs
new file mode 100644
index 000000000000..35388dba4234
--- /dev/null
+++ b/src/Controls/src/Core/HandlerImpl/Window.Windows.cs
@@ -0,0 +1,12 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Microsoft.Maui.Controls
+{
+	public partial class Window
+	{
+		internal UI.Xaml.Window NativeWindow =>
+			(Handler?.NativeView as UI.Xaml.Window) ?? throw new InvalidOperationException("Window Handler should have a Window set.");
+	}
+}
diff --git a/src/Controls/src/Core/Platform/ModalNavigationService/ModalNavigationService.Android.cs b/src/Controls/src/Core/Platform/ModalNavigationManager/ModalNavigationManager.Android.cs
similarity index 98%
rename from src/Controls/src/Core/Platform/ModalNavigationService/ModalNavigationService.Android.cs
rename to src/Controls/src/Core/Platform/ModalNavigationManager/ModalNavigationManager.Android.cs
index 4658af9edfd3..8a227199b9ac 100644
--- a/src/Controls/src/Core/Platform/ModalNavigationService/ModalNavigationService.Android.cs
+++ b/src/Controls/src/Core/Platform/ModalNavigationManager/ModalNavigationManager.Android.cs
@@ -12,7 +12,7 @@
 
 namespace Microsoft.Maui.Controls.Platform
 {
-	internal partial class ModalNavigationService
+	internal partial class ModalNavigationManager
 	{
 		partial void OnPageAttachedHandler()
 		{
@@ -166,9 +166,9 @@ internal bool HandleBackPressed()
 		class BackButtonCallBack : OnBackPressedCallback
 		{
 			WeakReference<Context> _weakReference;
-			ModalNavigationService? _service;
+			ModalNavigationManager? _service;
 
-			public BackButtonCallBack(ModalNavigationService service, Context context) : base(true)
+			public BackButtonCallBack(ModalNavigationManager service, Context context) : base(true)
 			{
 				_service = service;
 				_weakReference = new WeakReference<Context>(context);
diff --git a/src/Controls/src/Core/Platform/ModalNavigationService/ModalNavigationService.Standard.cs b/src/Controls/src/Core/Platform/ModalNavigationManager/ModalNavigationManager.Standard.cs
similarity index 88%
rename from src/Controls/src/Core/Platform/ModalNavigationService/ModalNavigationService.Standard.cs
rename to src/Controls/src/Core/Platform/ModalNavigationManager/ModalNavigationManager.Standard.cs
index 23ead192620c..c8893d0583f8 100644
--- a/src/Controls/src/Core/Platform/ModalNavigationService/ModalNavigationService.Standard.cs
+++ b/src/Controls/src/Core/Platform/ModalNavigationManager/ModalNavigationManager.Standard.cs
@@ -7,7 +7,7 @@
 
 namespace Microsoft.Maui.Controls.Platform
 {
-	internal partial class ModalNavigationService
+	internal partial class ModalNavigationManager
 	{
 		public Task<Page> PopModalAsync(bool animated)
 		{
diff --git a/src/Controls/src/Core/Platform/ModalNavigationManager/ModalNavigationManager.Windows.cs b/src/Controls/src/Core/Platform/ModalNavigationManager/ModalNavigationManager.Windows.cs
new file mode 100644
index 000000000000..eba41a3b2a74
--- /dev/null
+++ b/src/Controls/src/Core/Platform/ModalNavigationManager/ModalNavigationManager.Windows.cs
@@ -0,0 +1,154 @@
+#nullable enable
+
+using System;
+using System.Threading.Tasks;
+using Microsoft.Maui.Graphics;
+using Microsoft.UI.Xaml.Controls;
+
+namespace Microsoft.Maui.Controls.Platform
+{
+	internal partial class ModalNavigationManager
+	{
+		Page? _modalBackgroundPage;
+
+		Panel Container
+		{
+			get
+			{
+				if (_window.NativeWindow.Content is Panel p)
+					return p;
+
+				throw new InvalidOperationException("Root container Panel not found");
+			}
+		}
+
+		Rectangle ContainerBounds
+		{
+			get { return new Rectangle(0, 0, Container.ActualWidth, Container.ActualHeight); }
+		}
+
+		public  Task<Page> PopModalAsync(bool animated)
+		{
+			var tcs = new TaskCompletionSource<Page>();
+			var currentPage = _navModel.CurrentPage;
+			Page result = _navModel.PopModal();
+			SetCurrent(_navModel.CurrentPage, currentPage, true, () => tcs.SetResult(result));
+			return tcs.Task;
+		}
+
+		public Task PushModalAsync(Page modal, bool animated)
+		{
+			if (modal == null)
+				throw new ArgumentNullException(nameof(modal));
+
+			var tcs = new TaskCompletionSource<bool>();
+			var currentPage = _navModel.CurrentPage;
+			_navModel.PushModal(modal);
+			SetCurrent(modal, currentPage, false, () => tcs.SetResult(true));
+			return tcs.Task;
+		}
+
+		void AddPage(Page page)
+		{
+			if (Container == null || page == null)
+				return;
+
+			if (_modalBackgroundPage != null)
+				_modalBackgroundPage.GetCurrentPage()?.SendDisappearing();
+
+			page.ToNative(MauiContext);
+
+			var pageHandler = (INativeViewHandler)page.Handler;
+
+
+			if (pageHandler.ContainerView != null && !Container.Children.Contains(pageHandler.ContainerView))
+				Container.Children.Add(pageHandler.ContainerView);
+			else if (!Container.Children.Contains(pageHandler.NativeView))
+				Container.Children.Add(pageHandler.NativeView);
+
+			(page as IFrameworkElement).Measure(Container.ActualWidth, Container.ActualHeight);
+			(page as IFrameworkElement).Arrange(ContainerBounds);
+
+			page.Layout(ContainerBounds);
+		}
+
+		void RemovePage(Page page)
+		{
+			if (Container == null || page == null)
+				return;
+
+			if (_modalBackgroundPage != null)
+				_modalBackgroundPage.GetCurrentPage()?.SendAppearing();
+
+			var pageHandler = (INativeViewHandler)page.Handler;
+
+			if (Container.Children.Contains(pageHandler.NativeView))
+				Container.Children.Remove(pageHandler.NativeView);
+
+			if (Container.Children.Contains(pageHandler.ContainerView))
+				Container.Children.Remove(pageHandler.ContainerView);
+		}
+
+		partial void OnPageAttachedHandler()
+		{
+			if (_modalBackgroundPage != null)
+			{
+				RemovePage(_modalBackgroundPage);
+				_modalBackgroundPage.Cleanup();
+				_modalBackgroundPage.Parent = null;
+			}
+		}
+
+		void SetCurrent(Page newPage, Page previousPage, bool popping, Action? completedCallback = null)
+		{
+			bool modal = true;
+			try
+			{
+				if (modal && !popping && !newPage.BackgroundColor.IsDefault())
+					_modalBackgroundPage = previousPage;
+				else
+				{
+					RemovePage(previousPage);
+
+					if (!modal && _modalBackgroundPage != null)
+					{
+						RemovePage(_modalBackgroundPage);
+						_modalBackgroundPage.Cleanup();
+						_modalBackgroundPage.Parent = null;
+					}
+
+					_modalBackgroundPage = null;
+				}
+
+				if (popping)
+				{
+					//// Un-parent the page; otherwise the Resources Changed Listeners won't be unhooked and the 
+					//// page will leak 
+
+					previousPage.Cleanup();
+					previousPage.Parent = null;
+				}
+
+				newPage.Layout(ContainerBounds);
+
+				AddPage(newPage);
+
+				completedCallback?.Invoke();
+
+				// TODO MAUI WINUI STill needs a Toolbar
+				//UpdateToolbarTracker();
+				//await UpdateToolbarItems();
+			}
+			catch (Exception error)
+			{
+				//This exception prevents the Main Page from being changed in a child 
+				//window or a different thread, except on the Main thread. 
+				//HEX 0x8001010E 
+				if (error.HResult == -2147417842)
+					throw new InvalidOperationException("Changing the current page is only allowed if it's being called from the same UI thread." +
+						"Please ensure that the new page is in the same UI thread as the current page.");
+				throw;
+			}
+		}
+	}
+}
diff --git a/src/Controls/src/Core/Platform/ModalNavigationService/ModalNavigationService.cs b/src/Controls/src/Core/Platform/ModalNavigationManager/ModalNavigationManager.cs
similarity index 93%
rename from src/Controls/src/Core/Platform/ModalNavigationService/ModalNavigationService.cs
rename to src/Controls/src/Core/Platform/ModalNavigationManager/ModalNavigationManager.cs
index ad410e17de77..da11ff92bf23 100644
--- a/src/Controls/src/Core/Platform/ModalNavigationService/ModalNavigationService.cs
+++ b/src/Controls/src/Core/Platform/ModalNavigationManager/ModalNavigationManager.cs
@@ -8,7 +8,7 @@
 
 namespace Microsoft.Maui.Controls.Platform
 {
-	internal partial class ModalNavigationService
+	internal partial class ModalNavigationManager
 	{
 		Window _window;
 		public IReadOnlyList<Page> ModalStack => _navModel.Modals;
@@ -17,7 +17,7 @@ internal partial class ModalNavigationService
 		NavigationModel? _previousNavModel = null;
 		Page? _previousPage;
 
-		public ModalNavigationService(Window window)
+		public ModalNavigationManager(Window window)
 		{
 			_window = window;
 		}
@@ -60,6 +60,7 @@ internal void SettingNewPage()
 		}
 
 		partial void OnPageAttachedHandler();
+
 		public void PageAttachedHandler() => OnPageAttachedHandler();
 	}
 }
diff --git a/src/Controls/src/Core/Platform/ModalNavigationService/ModalNavigationService.iOS.cs b/src/Controls/src/Core/Platform/ModalNavigationManager/ModalNavigationManager.iOS.cs
similarity index 98%
rename from src/Controls/src/Core/Platform/ModalNavigationService/ModalNavigationService.iOS.cs
rename to src/Controls/src/Core/Platform/ModalNavigationManager/ModalNavigationManager.iOS.cs
index 0b9f0b9be312..ea561a457e80 100644
--- a/src/Controls/src/Core/Platform/ModalNavigationService/ModalNavigationService.iOS.cs
+++ b/src/Controls/src/Core/Platform/ModalNavigationManager/ModalNavigationManager.iOS.cs
@@ -10,7 +10,7 @@
 
 namespace Microsoft.Maui.Controls.Platform
 {
-	internal partial class ModalNavigationService
+	internal partial class ModalNavigationManager
 	{
 		UIViewController? _renderer
 		{
diff --git a/src/Controls/src/Core/Platform/ModalNavigationService/ModalNavigationService.Windows.cs b/src/Controls/src/Core/Platform/ModalNavigationService/ModalNavigationService.Windows.cs
deleted file mode 100644
index c984abca971a..000000000000
--- a/src/Controls/src/Core/Platform/ModalNavigationService/ModalNavigationService.Windows.cs
+++ /dev/null
@@ -1,22 +0,0 @@
-#nullable enable
-
-using System;
-using System.Collections.Generic;
-using System.Text;
-using System.Threading.Tasks;
-
-namespace Microsoft.Maui.Controls.Platform
-{
-	internal partial class ModalNavigationService
-	{
-		public  Task<Page> PopModalAsync(bool animated)
-		{
-			throw new NotImplementedException();
-		}
-
-		public Task PushModalAsync(Page modal, bool animated)
-		{
-			throw new NotImplementedException();
-		}
-	}
-}
diff --git a/src/Controls/src/Core/Platform/iOS/Extensions/PageExtensions.cs b/src/Controls/src/Core/Platform/PageExtensions.cs
similarity index 98%
rename from src/Controls/src/Core/Platform/iOS/Extensions/PageExtensions.cs
rename to src/Controls/src/Core/Platform/PageExtensions.cs
index 64eaf1e7931f..6af659f657db 100644
--- a/src/Controls/src/Core/Platform/iOS/Extensions/PageExtensions.cs
+++ b/src/Controls/src/Core/Platform/PageExtensions.cs
@@ -1,6 +1,5 @@
 using System;
 using System.Linq;
-using UIKit;
 
 namespace Microsoft.Maui.Controls.Platform
 {

From 6d000e78ada2554ff3c5ff9aa5822231c9389c31 Mon Sep 17 00:00:00 2001
From: Shane Neuville <shneuvil@microsoft.com>
Date: Tue, 6 Jul 2021 16:37:17 -0500
Subject: [PATCH 2/2] Modal gallery page

---
 src/Controls/samples/Controls.Sample/Startup.cs                | 2 +-
 .../samples/Controls.Sample/ViewModels/CoreViewModel.cs        | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/Controls/samples/Controls.Sample/Startup.cs b/src/Controls/samples/Controls.Sample/Startup.cs
index cd6eae592a9d..19de29f47875 100644
--- a/src/Controls/samples/Controls.Sample/Startup.cs
+++ b/src/Controls/samples/Controls.Sample/Startup.cs
@@ -98,7 +98,7 @@ public void Configure(IAppHostBuilder appBuilder)
 						{
 							PageType.Shell => typeof(AppShell),
 #if WINDOWS
-							PageType.Main => typeof(ModalPage),
+							PageType.Main => typeof(TempPage),
 #else
 							PageType.Main => typeof(CustomNavigationPage),
 #endif
diff --git a/src/Controls/samples/Controls.Sample/ViewModels/CoreViewModel.cs b/src/Controls/samples/Controls.Sample/ViewModels/CoreViewModel.cs
index f278bf0f47ca..6395cc2d6ee2 100644
--- a/src/Controls/samples/Controls.Sample/ViewModels/CoreViewModel.cs
+++ b/src/Controls/samples/Controls.Sample/ViewModels/CoreViewModel.cs
@@ -26,6 +26,9 @@ protected override IEnumerable<SectionModel> CreateItems() => new[]
 
 			new SectionModel(typeof(TransformationsPage), "Transformations",
 				"Apply scale transformations, rotation, etc. to a View."),
+
+			new SectionModel(typeof(ModalPage), "Modal",
+				"Allows you to push and pop Modal Pages."),
 		};
 	}
 }
\ No newline at end of file