From d75fa4fa9260496962099dcf2fae8ad30aee1349 Mon Sep 17 00:00:00 2001
From: Gerald Versluis <gerald.versluis@microsoft.com>
Date: Fri, 9 Aug 2019 02:51:06 +0200
Subject: [PATCH] [Bug] NullReferenceException Closing Window During Animation
 (#7067)

* Added null check to current application for WPF

* Apply suggestions from code review

Co-Authored-By: Samantha Houts <samhouts@users.noreply.github.com>
fixes #7061
---
 .../Issue7061.cs                                   | 37 ++++++++++++++++++++++
 .../Xamarin.Forms.Controls.Issues.Shared.projitems |  1 +
 Xamarin.Forms.Platform.WPF/WPFPlatformServices.cs  |  2 +-
 3 files changed, 39 insertions(+), 1 deletion(-)
 create mode 100644 Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue7061.cs

diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue7061.cs b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue7061.cs
new file mode 100644
index 0000000..5b06eaf
--- /dev/null
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue7061.cs
@@ -0,0 +1,37 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+
+namespace Xamarin.Forms.Controls.Issues
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Github, 7061, "[Bug] NullReferenceException Closing Window During Animation", PlatformAffected.UWP)]
+	public class Issue7061 : TestContentPage
+	{
+		Label _animatedLabel = new Label { Text = "Scaling out" };
+		Label _explanationLabel = new Label { Text = "When you close the app while the animation is still running you should not get an exception" };
+
+		protected override void Init()
+		{
+			var stack = new StackLayout
+			{
+				HorizontalOptions = LayoutOptions.Center,
+				VerticalOptions = LayoutOptions.Center
+			};
+
+			stack.Children.Add(_explanationLabel);
+			stack.Children.Add(_animatedLabel);
+
+			Content = stack;
+		}
+
+		protected override void OnAppearing()
+		{
+			base.OnAppearing();
+
+			_animatedLabel.ScaleTo(10, length: (uint)TimeSpan.FromMinutes(1).TotalMilliseconds);
+		}
+	}
+}
diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
index b80806b..1ac48fb 100644
--- a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
@@ -21,6 +21,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Issue6644.xaml.cs">
       <SubType>Code</SubType>
     </Compile>
+    <Compile Include="$(MSBuildThisFileDirectory)Issue7061.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)ShellGestures.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)ShellInsets.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)CollectionViewGrouping.cs" />
diff --git a/Xamarin.Forms.Platform.WPF/WPFPlatformServices.cs b/Xamarin.Forms.Platform.WPF/WPFPlatformServices.cs
index 8978807..ae53ab8 100644
--- a/Xamarin.Forms.Platform.WPF/WPFPlatformServices.cs
+++ b/Xamarin.Forms.Platform.WPF/WPFPlatformServices.cs
@@ -30,7 +30,7 @@ namespace Xamarin.Forms.Platform.WPF
 		
 		public void BeginInvokeOnMainThread(Action action)
 		{
-			System.Windows.Application.Current.Dispatcher.BeginInvoke(action);
+			System.Windows.Application.Current?.Dispatcher.BeginInvoke(action);
 		}
 
 		public Ticker CreateTicker()
-- 
2.7.4