Fixes 15049 (#15236)

* [UITest] Add test for 15049

* [Android] Calling _adapter.ItemCount here seems to cause ref to stick

Co-authored-by: Samantha Houts <samhouts@users.noreply.github.com>

Author: jfversluis

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/GitHub15049.cs

@@ -0,0 +1,103 @@
+using System;
+using System.Collections.ObjectModel;
+using System.Threading;
+using System.Threading.Tasks;
+using System.Windows.Input;
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+using System.Runtime.CompilerServices;
+using System.ComponentModel;
+
+#if UITEST
+using Xamarin.UITest;
+using NUnit.Framework;
+#endif
+
+namespace Xamarin.Forms.Controls.Issues
+{
+#if UITEST
+	[NUnit.Framework.Category(Core.UITests.UITestCategories.Github10000)]
+	[NUnit.Framework.Category(Core.UITests.UITestCategories.CollectionView)]
+	[NUnit.Framework.Category(Core.UITests.UITestCategories.ManualReview)]
+#endif
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Github, 15049, "[Android] CollectionView leaks GREF when items are removed", PlatformAffected.Android, issueTestNumber: 1)]
+	public class GitHub15049 : TestContentPage
+	{
+		protected override void Init()
+		{
+			BindingContext = new GitHub15049ViewModel();
+			var collectionView = new CollectionView();
+			collectionView.ItemsLayout = new LinearItemsLayout(ItemsLayoutOrientation.Vertical);
+			collectionView.ItemTemplate = new DataTemplate(() =>
+			 {
+				 var label = new Label();
+				 label.SetBinding(Label.TextProperty, "Text");
+
+				 return label;
+			 });
+			collectionView.SetBinding(CollectionView.ItemsSourceProperty, "Items");
+			Content = collectionView;
+		}
+
+		public class GitHub15049ViewModel : INotifyPropertyChanged
+		{
+			public event PropertyChangedEventHandler PropertyChanged;
+			private ObservableCollection<GitHub15049Model> _items;
+			public ObservableCollection<GitHub15049Model> Items
+			{
+				get => _items;
+				set
+				{
+					if (_items != value)
+					{
+						_items = value;
+						RaisePropertyChanged(nameof(Items));
+					}
+				}
+			}
+
+			public bool IsStopped { get; set; } = false;
+
+			public GitHub15049ViewModel()
+			{
+				var collection = new ObservableCollection<GitHub15049Model>();
+				var pageSize = 10000;
+
+				for (var i = 0; i < pageSize; i++)
+				{
+					collection.Add(new GitHub15049Model
+					{
+						Text = "Item " + i,
+					});
+				}
+
+				Items = collection;
+
+				//Kick off Test
+				Task.Run(async () =>
+				{
+					while (Items.Count > 0 && !IsStopped)
+					{
+						await Task.Yield();
+
+						await Device.InvokeOnMainThreadAsync(() =>
+						{
+							Items.RemoveAt(0);
+						});
+					}
+				});
+			}
+
+			protected virtual void RaisePropertyChanged([CallerMemberName] string propertyName = null)
+			{
+				PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+			}
+		}
+
+		public class GitHub15049Model
+		{
+			public string Text { get; set; }
+		}
+	}
+}

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

@@ -10,6 +10,7 @@
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="$(MSBuildThisFileDirectory)CollectionViewGroupTypeIssue.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)GitHub15049.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue10124.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue12603.xaml.cs">
       <DependentUpon>Issue12603.xaml</DependentUpon>

Xamarin.Forms.Platform.Android/CollectionView/AdapterNotifier.cs

@@ -30,8 +30,8 @@ public void NotifyItemInserted(IItemsViewSource source, int startIndex)
 			{
 				_adapter.NotifyItemInserted(startIndex);
 
-				var changedCount = _adapter.ItemCount - startIndex;
-				_adapter.NotifyItemRangeChanged(startIndex, changedCount);
+				//var changedCount = _adapter.ItemCount - startIndex;
+				//_adapter.NotifyItemRangeChanged(startIndex, changedCount);
 			}
 		}
 
@@ -41,9 +41,9 @@ public void NotifyItemMoved(IItemsViewSource source, int fromPosition, int toPos
 			{
 				_adapter.NotifyItemMoved(fromPosition, toPosition);
 
-				var minPosition = System.Math.Min(fromPosition, toPosition);
-				var changedCount = _adapter.ItemCount - minPosition;
-				_adapter.NotifyItemRangeChanged(minPosition, changedCount);
+				//var minPosition = System.Math.Min(fromPosition, toPosition);
+				//var changedCount = _adapter.ItemCount - minPosition;
+				//_adapter.NotifyItemRangeChanged(minPosition, changedCount);
 			}
 		}
 
@@ -59,8 +59,8 @@ public void NotifyItemRangeInserted(IItemsViewSource source, int startIndex, int
 			{
 				_adapter.NotifyItemRangeInserted(startIndex, count);
 
-				var changedCount = _adapter.ItemCount - startIndex;
-				_adapter.NotifyItemRangeChanged(startIndex, changedCount);
+				//var changedCount = _adapter.ItemCount - startIndex;
+				//_adapter.NotifyItemRangeChanged(startIndex, changedCount);
 			}
 		}
 
@@ -70,8 +70,8 @@ public void NotifyItemRangeRemoved(IItemsViewSource source, int startIndex, int
 			{
 				_adapter.NotifyItemRangeRemoved(startIndex, count);
 
-				var changedCount = _adapter.ItemCount - startIndex;
-				_adapter.NotifyItemRangeChanged(startIndex, changedCount);
+				//var changedCount = _adapter.ItemCount - startIndex;
+				//_adapter.NotifyItemRangeChanged(startIndex, changedCount);
 			}
 		}
 
@@ -81,8 +81,8 @@ public void NotifyItemRemoved(IItemsViewSource source, int startIndex)
 			{
 				_adapter.NotifyItemRemoved(startIndex);
 
-				var changedCount = _adapter.ItemCount - startIndex;
-				_adapter.NotifyItemRangeChanged(startIndex, changedCount);
+				//var changedCount = _adapter.ItemCount - startIndex;
+				//_adapter.NotifyItemRangeChanged(startIndex, changedCount);
 			}
 		}