[Android] ModalNavigationManager

Author: kubaflo

src/Controls/src/Core/Platform/ModalNavigationManager/ModalNavigationManager.Android.cs

@@ -197,7 +197,8 @@ async Task PresentModal(Page modal, bool animated)
 			var dialogFragment = new ModalFragment(WindowMauiContext, modal)
 			{
 				Cancelable = false,
-				IsAnimated = animated
+				IsAnimated = animated,
+				modalNavigationManager = this
 			};
 
 			var fragmentManager = WindowMauiContext.GetFragmentManager();
@@ -236,6 +237,7 @@ internal class ModalFragment : DialogFragment
 
 			public event EventHandler? AnimationEnded;
 
+			public ModalNavigationManager? modalNavigationManager { get; internal set; }
 
 			public bool IsAnimated { get; internal set; }
 
@@ -249,7 +251,7 @@ public ModalFragment(IMauiContext mauiContext, Page modal)
 
 			public override global::Android.App.Dialog OnCreateDialog(Bundle? savedInstanceState)
 			{
-				var dialog = new CustomComponentDialog(RequireContext(), Theme);
+				var dialog = new CustomComponentDialog(RequireContext(), Theme, modalNavigationManager);
 
 				if (dialog is null || dialog.Window is null)
 					throw new InvalidOperationException($"{dialog} or {dialog?.Window} is null, and it's invalid");
@@ -404,18 +406,21 @@ void FireAnimationEnded()
 
 			sealed class CustomComponentDialog : ComponentDialog
 			{
-				public CustomComponentDialog(Context context, int themeResId) : base(context, themeResId)
+				public CustomComponentDialog(Context context, int themeResId, ModalNavigationManager? modalNavigationManager) : base(context, themeResId)
 				{
-					this.OnBackPressedDispatcher.AddCallback(new CallBack(true, this));
+					this.OnBackPressedDispatcher.AddCallback(new CallBack(true, this, modalNavigationManager));
 				}
 
 				sealed class CallBack : OnBackPressedCallback
 				{
 					WeakReference<CustomComponentDialog> _customComponentDialog;
 
-					public CallBack(bool enabled, CustomComponentDialog customComponentDialog) : base(enabled)
+					private ModalNavigationManager? _modalNavigationManager;
+
+					public CallBack(bool enabled, CustomComponentDialog customComponentDialog, ModalNavigationManager? modalNavigationManager) : base(enabled)
 					{
 						_customComponentDialog = new(customComponentDialog);
+						_modalNavigationManager = modalNavigationManager;
 					}
 
 					public override void HandleOnBackPressed()
@@ -453,7 +458,7 @@ public override void HandleOnBackPressed()
 
 						if (!preventBackPropagation)
 						{
-							customComponentDialog.OnBackPressedDispatcher.OnBackPressed();
+							_ = _modalNavigationManager?.PopModalAsync(true);
 						}
 
 						eventHandler = null;

src/Controls/tests/TestCases.HostApp/Issues/Issue28811.cs

@@ -0,0 +1,31 @@
+[Issue(IssueTracker.Github, 28811, "Overriding back button functionality with OnBackButtonPressed returning false in a modally pushed page causes stack overflow", PlatformAffected.Android)]
+public class Issue28811 : ContentPage
+{
+	public Issue28811()
+	{
+		Content = new Button()
+		{
+			AutomationId = "NavigateToDetailPage",
+			HeightRequest = 50,
+			Text = "Navigate to Detail Page",
+			Command = new Command(() => Navigation.PushModalAsync(new Issue28811DetailPage()))
+		};
+	}
+
+	class Issue28811DetailPage : ContentPage
+	{
+		public Issue28811DetailPage()
+		{
+			Content = new Label()
+			{
+				AutomationId = "Issue28811DetailPage",
+				Text = "Hello, World!",
+			};
+		}
+
+		protected override bool OnBackButtonPressed()
+		{
+			return false;
+		}
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue28811.cs

@@ -0,0 +1,24 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+public class Issue28811 : _IssuesUITest
+{
+	public Issue28811(TestDevice testDevice) : base(testDevice)
+	{
+	}
+
+	public override string Issue => "Overriding back button functionality with OnBackButtonPressed returning false in a modally pushed page causes stack overflow";
+
+	[Test]
+	[Category(UITestCategories.Navigation)]
+	public void OverridingBackButtonShouldNotCauseStackOverflow()
+	{
+		App.WaitForElement("NavigateToDetailPage");
+		App.Click("NavigateToDetailPage");
+		App.WaitForElement("Issue28811DetailPage");
+		App.Back();
+		App.WaitForElement("NavigateToDetailPage");
+	}
+}