Add check if View is not disposed to prevent NRE for Android Button (#…

…14760)

* Add test + fix

* Add UI Test

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue14757.cs

@@ -0,0 +1,140 @@
+using System;
+using System.Collections.ObjectModel;
+using NUnit.Framework;
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+
+namespace Xamarin.Forms.Controls.Issues
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Github, 14757, "[Bug] Android ObjectDisposedException thrown Button inside CollectionView with Binding", PlatformAffected.Android)]
+	public class Issue14757 : TestContentPage
+	{
+		public ObservableCollection<int> Values { get; set; } = new ObservableCollection<int>();
+
+		public static readonly BindableProperty SomeTextProperty = BindableProperty.Create(nameof(SomeText), typeof(string), typeof(Issue14757), default(string));
+		public string SomeText
+		{
+			get { return (string)GetValue(SomeTextProperty); }
+			set { SetValue(SomeTextProperty, value); }
+		}
+
+		public Issue14757()
+		{
+			SomeText = "Default";
+
+			for (int i = 0; i <= 1000; i++)
+				Values.Add(i);
+
+			BindingContext = this;
+		}
+
+		const string LabelAutomationId = "TheStatusLabel";
+		const string GoToPageAutomationId = "GoToPageButton";
+		const string ChangeTextAutomationId = "ChangeTextButton";
+
+		protected override void Init()
+		{
+			var statusLabel = new Label()
+			{
+				AutomationId = LabelAutomationId
+			};
+			statusLabel.SetBinding(Label.TextProperty, new Binding("SomeText"));
+
+			var button1 = new Button
+			{
+				Text = "To testpage",
+				AutomationId = GoToPageAutomationId
+			};
+			button1.Clicked += Button1_Clicked;
+
+			var button2 = new Button
+			{
+				Text = "Change Text",
+				AutomationId = ChangeTextAutomationId
+			};
+			button2.Clicked += Button2_Clicked;
+
+			var stackLayout = new StackLayout
+			{
+				Children = {
+					statusLabel,
+					button1,
+					button2
+				}
+			};
+
+			Content = stackLayout;
+		}
+
+		private void Button2_Clicked(object sender, EventArgs e)
+		{
+			SomeText = SomeText == "Default" ? "Some Value" : "Default";
+		}
+
+		private async void Button1_Clicked(object sender, EventArgs e)
+		{
+			await Navigation.PushAsync(new NewPage(this));
+		}
+
+		class NewPage : ContentPage
+		{
+			public Issue14757 MyMainPage { get; set; }
+
+			public NewPage(Issue14757 mainpage)
+			{
+				BindingContext = MyMainPage = mainpage;
+
+				var dataTemplate = new DataTemplate(() =>
+				{
+					var button = new Button();
+					button.SetBinding(Button.TextProperty, new Binding("SomeText", source: MyMainPage));
+
+					var stackLayout = new StackLayout
+					{
+						Children =
+						{
+							button
+						}
+					};
+
+					return stackLayout;
+				});
+
+				var collectionView = new CollectionView();
+				collectionView.SetBinding(CollectionView.ItemsSourceProperty, new Binding("Values"));
+				collectionView.ItemTemplate = dataTemplate;
+
+				var stackLayout = new StackLayout
+				{
+					Children =
+					{
+						collectionView
+					}
+				};
+
+				Content = stackLayout;
+			}
+		}
+
+#if UITEST
+		[Test]
+		public void Issue14757Test()
+		{
+			System.Threading.Tasks.Task.Delay(500);
+
+			RunningApp.WaitForElement(LabelAutomationId);
+
+			for (int i = 0; i <= 10; i++)
+			{
+				RunningApp.Tap(GoToPageAutomationId);
+				System.Threading.Tasks.Task.Delay(500);
+				RunningApp.Back();
+			}
+
+			RunningApp.Tap(ChangeTextAutomationId);
+			RunningApp.WaitForElement("Some Value");
+		}
+#endif
+	}
+}

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

@@ -1808,6 +1808,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Issue14505.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue14505-II.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue6387.xaml.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Issue14757.cs" />
   </ItemGroup>
   <ItemGroup>
     <EmbeddedResource Include="$(MSBuildThisFileDirectory)Bugzilla22229.xaml">
@@ -2902,7 +2903,7 @@
   <ItemGroup>
     <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue14095.xaml">
       <SubType>Designer</SubType>
-      <Generator>MSBuild:Compile</Generator>
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
     </EmbeddedResource>
   </ItemGroup>
 </Project>

Xamarin.Forms.Platform.Android/ButtonLayoutManager.cs

@@ -265,7 +265,7 @@ void UpdatePadding()
 		bool UpdateTextAndImage()
 		{
 
-			if (_disposed || _renderer?.View == null || _element == null)
+			if (_disposed || _renderer?.View == null || _element == null || (View?.IsDisposed() ?? true))
 				return false;
 
 			if (View?.LayoutParameters == null && _hasLayoutOccurred)