Invoke AnimationFinished from fragment if no animation has been added

Xamarin.Forms.ControlGallery.Android/CustomRenderers.cs

@@ -52,13 +52,39 @@
 [assembly: ExportRenderer(typeof(Xamarin.Forms.Controls.Tests.TestClasses.CustomButton), typeof(CustomButtonRenderer))]
 [assembly: ExportRenderer(typeof(ScrolView11185), typeof(ScrollViewFadeRenderer))]
 
+[assembly: ExportRenderer(typeof(ShellWithCustomRendererDisabledAnimations), typeof(ShellWithCustomRendererDisabledAnimationsRenderer))]
+
 #if PRE_APPLICATION_CLASS
 #elif FORMS_APPLICATION_ACTIVITY
 #else
 [assembly: ExportRenderer(typeof(FlyoutPage), typeof(NativeDroidFlyoutPage))]
 #endif
 namespace Xamarin.Forms.ControlGallery.Android
 {
+	public class ShellWithCustomRendererDisabledAnimationsRenderer : ShellRenderer
+	{
+		public ShellWithCustomRendererDisabledAnimationsRenderer(Context context) : base(context)
+		{
+		}
+
+		protected override IShellItemRenderer CreateShellItemRenderer(ShellItem shellItem)
+		{
+			return new ShellWithCustomRendererDisabledAnimationsShellItemRenderer(this);
+		}
+
+		public class ShellWithCustomRendererDisabledAnimationsShellItemRenderer : ShellItemRenderer
+		{
+			public ShellWithCustomRendererDisabledAnimationsShellItemRenderer(IShellContext shellContext) : base(shellContext)
+			{
+			}
+
+			protected override void SetupAnimation(ShellNavigationSource navSource, AndroidX.Fragment.App.FragmentTransaction t, Page page)
+			{
+				// Don't setup any animations
+			}
+		}
+	}
+
 	public sealed class ScrollViewFadeRenderer : ScrollViewRenderer
 	{
 		public ScrollViewFadeRenderer(Context context) : base(context)

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/ShellWithCustomRendererDisabledAnimations.cs

@@ -0,0 +1,78 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Text;
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+
+
+#if UITEST
+using Xamarin.UITest;
+using NUnit.Framework;
+using Xamarin.Forms.Core.UITests;
+#endif
+
+namespace Xamarin.Forms.Controls.Issues
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.None, 0, "[Shell] Overriding animation with custom renderer to remove animation breaks next navigation",
+		PlatformAffected.All)]
+#if UITEST
+	[NUnit.Framework.Category(UITestCategories.Shell)]
+#endif
+	public class ShellWithCustomRendererDisabledAnimations : TestShell
+	{
+		protected override void Init()
+		{
+			ContentPage contentPage = new ContentPage();
+			base.AddFlyoutItem(contentPage, "Root");
+
+			contentPage.Content = new Button()
+			{
+				Text = "Click Me",
+				AutomationId = "PageLoaded",
+				Command = new Command(async () =>
+				{
+					await Navigation.PushAsync(CreateSecondPage());
+				})
+			};
+		}
+
+		ContentPage CreateSecondPage()
+		{
+			ContentPage page = new ContentPage();
+
+			page.Content = new StackLayout()
+			{
+				Children =
+				{
+					new Label()
+					{
+						Text = "If clicking `Go Back` goes back to previous page then test has passed"
+					},
+					new Button()
+					{
+						Text = "Go Back",
+						Command	= new Command(async () =>
+						{
+							await GoToAsync("..");
+						}),
+						AutomationId = "GoBack"
+					}
+				}
+			};
+
+			return page;
+		}
+
+#if UITEST  && __ANDROID__
+		[Test]
+		public void NavigationWithACustomRendererThatDoesntSetAnAnimationStillWorks()
+		{
+			RunningApp.Tap("PageLoaded");
+			RunningApp.Tap("GoBack");
+			RunningApp.WaitForElement("PageLoaded");
+		}
+#endif
+	}
+}

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems

@@ -12,6 +12,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)CollectionViewGroupTypeIssue.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue11214.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue13109.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)ShellWithCustomRendererDisabledAnimations.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)ShellFlyoutContent.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue4720.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue10897.xaml.cs">

Xamarin.Forms.Core/Shell/ShellNavigationManager.cs

@@ -53,12 +53,15 @@ public async Task GoToAsync(ShellNavigationParameters shellNavigationParameters)
 			{
 				var navigatingArgs = ProposeNavigation(source, state, _shell.CurrentState != null, animate ?? true);
 
-				bool accept = !navigatingArgs.NavigationDelayedOrCancelled;
-				if (navigatingArgs.DeferredTask != null)
-					accept = await navigatingArgs.DeferredTask;
+				if (navigatingArgs != null)
+				{
+					bool accept = !navigatingArgs.NavigationDelayedOrCancelled;
+					if (navigatingArgs.DeferredTask != null)
+						accept = await navigatingArgs.DeferredTask;
 
-				if (!accept)
-					return;
+					if (!accept)
+						return;
+				}
 			}
 
 			Routing.RegisterImplicitPageRoutes(_shell);

Xamarin.Forms.Platform.Android/Renderers/ShellContentFragment.cs

@@ -71,7 +71,7 @@ public ShellContentFragment(IShellContext shellContext, Page page)
 		public event EventHandler AnimationFinished;
 
 		public Fragment Fragment => this;
-
+				
 		public override AndroidAnimation OnCreateAnimation(int transit, bool enter, int nextAnim)
 		{
 			var result = base.OnCreateAnimation(transit, enter, nextAnim);
@@ -82,7 +82,10 @@ public override AndroidAnimation OnCreateAnimation(int transit, bool enter, int
 			}
 
 			if (result == null)
+			{
+				AnimationFinished?.Invoke(this, EventArgs.Empty);
 				return result;
+			}
 
 			// we only want to use a hardware layer for the entering view because its quite likely
 			// the view exiting is animating a button press of some sort. This means lots of GPU