[Android] Fix: Modal Animation Repeats When Returning from Background 2 (#29557)

* [Android] clean up modalnavigationmanager

* fix failing tests

* Handle animation while poping

* subscribe to event before showing dailog

* change style's names

* apply new styles

* set result to tcs once dailog dismiss

Author: bhavanesh2001

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

@@ -1,20 +1,14 @@
 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
-using System.Linq;
-using System.Runtime.CompilerServices;
 using System.Threading.Tasks;
 using Android.Content;
 using Android.Graphics.Drawables;
 using Android.OS;
-using Android.Runtime;
 using Android.Views;
-using Android.Views.Animations;
 using AndroidX.Activity;
-using AndroidX.AppCompat.App;
 using AndroidX.Fragment.App;
 using Microsoft.Maui.LifecycleEvents;
-using AAnimation = Android.Views.Animations.Animation;
 using AColor = Android.Graphics.Color;
 using AView = Android.Views.View;
 
@@ -23,9 +17,6 @@ namespace Microsoft.Maui.Controls.Platform
 	internal partial class ModalNavigationManager
 	{
 		ViewGroup? _modalParentView;
-		bool _navAnimationInProgress;
-		internal const string CloseContextActionsSignalName = "Xamarin.CloseContextActions";
-		AAnimation? _dismissAnimation;
 		bool _platformActivated;
 
 		readonly Stack<string> _modals = [];
@@ -44,8 +35,6 @@ void OnWindowPropertyChanging(object sender, PropertyChangingEventArgs e)
 				return;
 			}
 
-			var handler = _currentPage?.Handler;
-			var windowP = _window.Page;
 			if (CurrentPage is not null &&
 				_window.Page != CurrentPage)
 			{
@@ -89,76 +78,45 @@ internal void SetModalParentView(ViewGroup viewGroup)
 			_modalParentView = viewGroup;
 		}
 
-		ViewGroup GetModalParentView()
-		{
-			return _modalParentView ??
-				_window?.PlatformActivity?.Window?.DecorView as ViewGroup ??
-				throw new InvalidOperationException("Root View Needs to be set");
-		}
-
-		// AFAICT this is specific to ListView and Context Items
-		internal bool NavAnimationInProgress
-		{
-			get { return _navAnimationInProgress; }
-			set
-			{
-				if (_navAnimationInProgress == value)
-					return;
-				_navAnimationInProgress = value;
-
-#pragma warning disable CS0618 // TODO: Remove when we internalize/replace MessagingCenter
-				if (value)
-					MessagingCenter.Send(this, CloseContextActionsSignalName);
-#pragma warning restore CS0618 // Type or member is obsolete
-			}
-		}
-
 		Task<Page> PopModalPlatformAsync(bool animated)
 		{
 			Page modal = CurrentPlatformModalPage;
 			_platformModalPages.Remove(modal);
 
+			TaskCompletionSource<Page> tcs = new();
+
 			var fragmentManager = WindowMauiContext.GetFragmentManager();
 
 			var dialogFragmentId = _modals.Pop();
 			var dialogFragment = (ModalFragment?)fragmentManager.FindFragmentByTag(dialogFragmentId);
-
-			// If for the dialog is null what we want to do?
+			
 			if (dialogFragment is null)
 			{
-				return Task.FromResult(modal);
+				tcs.TrySetResult(modal);
+				return tcs.Task;
 			}
 
-			var source = new TaskCompletionSource<Page>();
+			EventHandler? OnDialogDismiss = null;
 
-			if (animated && dialogFragment.View is not null)
+			OnDialogDismiss = (_, _) =>
 			{
-				_dismissAnimation ??= AnimationUtils.LoadAnimation(WindowMauiContext.Context, Resource.Animation.nav_modal_default_exit_anim)!;
+				dialogFragment.DialogDismissEvent -= OnDialogDismiss;
+				tcs.TrySetResult(modal);
+			};
 
-				_dismissAnimation.AnimationEnd += OnAnimationEnded;
+			dialogFragment.DialogDismissEvent += OnDialogDismiss;
 
-				dialogFragment.View.StartAnimation(_dismissAnimation);
+			if (animated)
+			{
+				dialogFragment.Dialog?.Window?.SetWindowAnimations(Resource.Style.modal_exit_animation);
+				modal.Dispatcher.Dispatch(() => dialogFragment.Dismiss());
 			}
 			else
 			{
 				dialogFragment.Dismiss();
-				source.TrySetResult(modal);
 			}
 
-			return source.Task;
-
-			void OnAnimationEnded(object? sender, AAnimation.AnimationEndEventArgs e)
-			{
-				if (sender is not AAnimation animation)
-				{
-					return;
-				}
-
-				animation.AnimationEnd -= OnAnimationEnded;
-				dialogFragment.Dismiss();
-				source.TrySetResult(modal);
-				_dismissAnimation = null;
-			}
+			return tcs.Task;
 		}
 
 		// The CurrentPage doesn't represent the root of the platform hierarchy.
@@ -192,8 +150,6 @@ async Task PresentModal(Page modal, bool animated)
 		{
 			TaskCompletionSource<bool> animationCompletionSource = new();
 
-			var parentView = GetModalParentView();
-
 			var dialogFragment = new ModalFragment(WindowMauiContext, modal)
 			{
 				Cancelable = false,
@@ -203,39 +159,30 @@ async Task PresentModal(Page modal, bool animated)
 			var fragmentManager = WindowMauiContext.GetFragmentManager();
 			var dialogFragmentId = AView.GenerateViewId().ToString();
 			_modals.Push(dialogFragmentId);
-			dialogFragment.Show(fragmentManager, dialogFragmentId);
-
-			if (animated)
-			{
-				NavAnimationInProgress = true;
-				dialogFragment!.AnimationEnded += OnAnimationEnded;
 
-				await animationCompletionSource.Task;
-			}
-			else
-			{
-				NavAnimationInProgress = false;
-				animationCompletionSource.TrySetResult(true);
-			}
+			EventHandler? OnDialogShown = null;
 
-			void OnAnimationEnded(object? sender, EventArgs e)
+			OnDialogShown = (_, _) =>
 			{
-				dialogFragment!.AnimationEnded -= OnAnimationEnded;
-				NavAnimationInProgress = false;
+				dialogFragment!.DialogShowEvent -= OnDialogShown;
 				animationCompletionSource.SetResult(true);
-			}
+			};
+
+			dialogFragment!.DialogShowEvent += OnDialogShown;
+
+			dialogFragment.Show(fragmentManager, dialogFragmentId);
+
+			await animationCompletionSource.Task;
 		}
 
 		internal class ModalFragment : DialogFragment
 		{
 			Page _modal;
 			IMauiContext _mauiWindowContext;
 			NavigationRootManager? _navigationRootManager;
+			public event EventHandler? DialogShowEvent;
+			public event EventHandler? DialogDismissEvent;
 			static readonly ColorDrawable TransparentColorDrawable = new(AColor.Transparent);
-			bool _pendingAnimation = true;
-
-			public event EventHandler? AnimationEnded;
-
 
 			public bool IsAnimated { get; internal set; }
 
@@ -263,6 +210,20 @@ public ModalFragment(IMauiContext mauiContext, Page modal)
 				{
 					dialog.Window.SetSoftInputMode(attributes.SoftInputMode);
 				}
+				EventHandler? OnDialogShown = null;
+
+				OnDialogShown = (_, _) =>
+				{
+					dialog.ShowEvent -= OnDialogShown;
+					DialogShowEvent?.Invoke(this, EventArgs.Empty);
+				};
+
+				dialog.ShowEvent += OnDialogShown;
+
+				if (IsAnimated)
+				{
+					dialog.Window?.SetWindowAnimations(Resource.Style.modal_enter_animation);
+				}
 
 				if (mainActivityWindow is not null)
 				{
@@ -356,29 +317,13 @@ public override void OnStart()
 				int width = ViewGroup.LayoutParams.MatchParent;
 				int height = ViewGroup.LayoutParams.MatchParent;
 				dialog.Window.SetLayout(width, height);
-
-				if (IsAnimated)
-				{
-					var animation = AnimationUtils.LoadAnimation(_mauiWindowContext.Context, Resource.Animation.nav_modal_default_enter_anim)!;
-					View.StartAnimation(animation);
-
-					animation.AnimationEnd += OnAnimationEnded;
-				}
-
-				void OnAnimationEnded(object? sender, AAnimation.AnimationEndEventArgs e)
-				{
-					if (sender is not AAnimation animation)
-					{
-						return;
-					}
-
-					animation.AnimationEnd -= OnAnimationEnded;
-					FireAnimationEnded();
-				}
 			}
 
 			public override void OnDismiss(IDialogInterface dialog)
 			{
+				base.OnDismiss(dialog);
+				DialogDismissEvent?.Invoke(this, EventArgs.Empty);
+				DialogDismissEvent = null;
 				_modal.PropertyChanged -= OnModalPagePropertyChanged;
 				_modal.HandlerChanged -= OnPageHandlerChanged;
 
@@ -391,28 +336,9 @@ public override void OnDismiss(IDialogInterface dialog)
 				_modal = null!;
 				_mauiWindowContext = null!;
 				_navigationRootManager?.Disconnect();
-				_navigationRootManager = null;
-				base.OnDismiss(dialog);
-			}
-
-			public override void OnDestroy()
-			{
-				base.OnDestroy();
-				FireAnimationEnded();
+				_navigationRootManager = null;				
 			}
 
-			void FireAnimationEnded()
-			{
-				if (!_pendingAnimation)
-				{
-					return;
-				}
-
-				_pendingAnimation = false;
-				AnimationEnded?.Invoke(this, EventArgs.Empty);
-			}
-
-
 			sealed class CustomComponentDialog : ComponentDialog
 			{
 				public CustomComponentDialog(Context context, int themeResId) : base(context, themeResId)

src/Core/src/Platform/Android/Resources/values/styles.xml

@@ -101,4 +101,11 @@
   <style name="scrollViewTheme">
     <item name="scrollViewStyle">@style/scrollViewScrollBars</item>
   </style>
+
+  <style name="modal_enter_animation" >
+    <item name="android:windowEnterAnimation">@anim/nav_modal_default_enter_anim</item>
+  </style>
+  <style name="modal_exit_animation" >
+    <item name="android:windowExitAnimation">@anim/nav_modal_default_exit_anim</item>
+  </style>
 </resources>