Fix Customised CollectionView inherited from does not ScrollTo and display selection correctly

src/Controls/src/Core/Handlers/Items/ItemsViewHandler.Windows.cs

@@ -659,7 +659,7 @@ object FindBoundItem(ScrollToRequestEventArgs args)
 			{
 				if (CollectionViewSource.View[n] is ItemTemplateContext pair)
 				{
-					if (pair.Item == args.Item)
+					if (Equals(pair.Item, args.Item))
 					{
 						return CollectionViewSource.View[n];
 					}

src/Controls/tests/TestCases.HostApp/Issues/Issue31351.cs

@@ -0,0 +1,282 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Diagnostics;
+using System.Linq;
+using System.Text;
+using System.Windows.Input;
+using Microsoft.Maui.Controls;
+
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 31351, "[WinUI] Custom CollectionView does not work on ScrollTo", PlatformAffected.All)]
+public partial class Issue31351 : ContentPage
+{
+	readonly Issue31351CustomCollectionView<Issue31351StartupPageModel.Issue31351DisplayItem> _customCollectionView;
+	readonly Issue31351StartupPageModel _viewModel;
+
+	public Issue31351()
+	{
+		_viewModel = new Issue31351StartupPageModel();
+		BindingContext = _viewModel;
+
+		var scrollButton = new Button
+		{
+			Text = "Scroll to Mid",
+			AutomationId = "Issue31351ScrollButton"
+		};
+		scrollButton.Clicked += (s, e) =>
+		{
+			_viewModel.Scroll.Execute(null);
+		};
+
+		var scrollButton2 = new Button
+		{
+			Text = "Scroll to Top",
+			AutomationId = "Issue31351TopScrollButton"
+		};
+		scrollButton2.HeightRequest = 50;
+		scrollButton2.Clicked += (s, e) =>
+		{
+			_customCollectionView.ScrollTo(0, position: ScrollToPosition.Center, animate: true);
+		};
+
+		var statusLabel = new Label
+		{
+			Text = "Ready - Tap buttons to test ScrollTo functionality",
+			AutomationId = "Issue31351StatusLabel",
+			BackgroundColor = Colors.LightYellow,
+			Padding = new Thickness(10),
+			HorizontalTextAlignment = TextAlignment.Center
+		};
+
+		_customCollectionView = new Issue31351CustomCollectionView<Issue31351StartupPageModel.Issue31351DisplayItem>
+		{
+			AutomationId = "Issue31351CollectionView",
+			Margin = 10,
+			BackgroundColor = Colors.LightGray
+		};
+		_customCollectionView.SetBinding(Issue31351CustomCollectionView<Issue31351StartupPageModel.Issue31351DisplayItem>.CustomItemsSourceProperty,
+			new Binding(nameof(Issue31351StartupPageModel.DisplayItems), BindingMode.TwoWay, source: _viewModel));
+		_customCollectionView.SetBinding(Issue31351CustomCollectionView<Issue31351StartupPageModel.Issue31351DisplayItem>.CustomSelectedItemProperty,
+			new Binding(nameof(Issue31351StartupPageModel.SelectedDisplayItem), BindingMode.TwoWay, source: _viewModel));
+		_customCollectionView.SetBinding(Issue31351CustomCollectionView<Issue31351StartupPageModel.Issue31351DisplayItem>.InvalidateCommandProperty,
+			new Binding(nameof(Issue31351StartupPageModel.InvalidateTreeviewCommand), BindingMode.OneWayToSource, source: _viewModel));
+
+
+		_customCollectionView.Scrolled += (sender, e) =>
+		{
+			statusLabel.Text = $"Scrolled: First={e.FirstVisibleItemIndex}, Center={e.CenterItemIndex}, Last={e.LastVisibleItemIndex}";
+		};
+
+
+		var layoutGrid = new Grid();
+		layoutGrid.RowDefinitions.Add(new RowDefinition { Height = new GridLength(1, GridUnitType.Auto) });
+		layoutGrid.RowDefinitions.Add(new RowDefinition { Height = new GridLength(1, GridUnitType.Auto) });
+		layoutGrid.RowDefinitions.Add(new RowDefinition { Height = new GridLength(1, GridUnitType.Auto) });
+		layoutGrid.RowDefinitions.Add(new RowDefinition { Height = new GridLength(1, GridUnitType.Star) });
+		layoutGrid.ColumnDefinitions.Add(new ColumnDefinition { Width = new GridLength(1, GridUnitType.Star) });
+
+		layoutGrid.Add(scrollButton, 0, 0);
+		layoutGrid.Add(scrollButton2, 0, 1);
+		layoutGrid.Add(statusLabel, 0, 2);
+		layoutGrid.Add(_customCollectionView, 0, 3);
+
+		Content = layoutGrid;
+	}
+
+	protected override void OnAppearing()
+	{
+		base.OnAppearing();
+		_viewModel.OnAppearing.Execute(null);
+	}
+}
+
+internal class Issue31351StartupPageModel : INotifyPropertyChanged
+{
+	public class Issue31351DisplayItem : IIssue31351TreeviewItem
+	{
+		public string Title { get; set; }
+	}
+
+	public List<Issue31351DisplayItem> DisplayItems { get; set; } = new();
+
+	Issue31351DisplayItem _displayItem;
+	public Issue31351DisplayItem SelectedDisplayItem
+	{
+		get { return _displayItem; }
+		set { _displayItem = value; OnPropertyChanged("SelectedDisplayItem"); }
+	}
+
+	public Action InvalidateTreeviewCommand { get; set; }
+
+	public class Issue31351DataItem
+	{
+		public int Id { get; set; }
+		public string Name { get; set; }
+	}
+
+	public List<Issue31351DataItem> data = new();
+
+	public Issue31351StartupPageModel()
+	{
+		#region *// Generate test data
+		for (int i = 0; i < 100; i++)
+		{
+			data.Add(new Issue31351DataItem { Id = i, Name = $"Item {i}" });
+		}
+		#endregion
+	}
+	public event PropertyChangedEventHandler PropertyChanged;
+	public void OnPropertyChanged(string name)
+	{
+		if (this.PropertyChanged != null)
+			this.PropertyChanged(this, new PropertyChangedEventArgs(name));
+	}
+
+	public ICommand OnAppearing => new Command(() =>
+	{
+		DisplayItems.Clear();
+		foreach (var dataItem in data)
+		{
+			DisplayItems.Add(new Issue31351DisplayItem { Title = dataItem.Name });
+		}
+
+		SelectedDisplayItem = DisplayItems[5];
+		InvalidateTreeviewCommand?.Invoke();
+	});
+
+	public ICommand Scroll => new Command(() =>
+	{
+		SelectedDisplayItem = DisplayItems[50];
+		InvalidateTreeviewCommand?.Invoke();
+	});
+}
+
+public interface IIssue31351TreeviewItem
+{
+	string Title { get; set; }
+}
+
+internal class Issue31351CustomCollectionView<T> : CollectionView where T : IIssue31351TreeviewItem
+{
+	#region *// Bindable properties
+
+	#region *// Item source
+	public static readonly BindableProperty CustomItemsSourceProperty = BindableProperty.Create(
+		nameof(CustomItemsSource),
+		typeof(List<T>),
+		typeof(Issue31351CustomCollectionView<T>),
+		null);
+
+	public List<T> CustomItemsSource
+	{
+		get { return (List<T>)GetValue(CustomItemsSourceProperty); }
+		set { SetValue(CustomItemsSourceProperty, value); }
+	}
+	#endregion
+
+	#region *// InvalidateCommand
+	public static BindableProperty InvalidateCommandProperty = BindableProperty.Create(
+		nameof(InvalidateCommand),
+		typeof(Action),
+		typeof(Issue31351CustomCollectionView<T>),
+		null,
+		BindingMode.OneWayToSource);
+
+	public Action InvalidateCommand
+	{
+		get { return (Action)GetValue(InvalidateCommandProperty); }
+		set { SetValue(InvalidateCommandProperty, value); }
+	}
+	#endregion
+
+	#region *// Selected item
+	public static readonly BindableProperty CustomSelectedItemProperty = BindableProperty.Create(
+		nameof(CustomSelectedItem),
+		typeof(IIssue31351TreeviewItem),
+		typeof(Issue31351CustomCollectionView<T>),
+		null);
+
+	public IIssue31351TreeviewItem CustomSelectedItem
+	{
+		get { return (IIssue31351TreeviewItem)GetValue(CustomSelectedItemProperty); }
+		set { SetValue(CustomSelectedItemProperty, value); }
+	}
+	#endregion
+
+	#endregion
+
+	public class Issue31351CollectionViewItem
+	{
+		public string Title { get; set; }
+
+		public override bool Equals(object obj)
+		{
+			if (obj == null)
+				return false;
+			if (obj is not Issue31351CollectionViewItem)
+				return false;
+			return ((Issue31351CollectionViewItem)this).Title.Equals(((Issue31351CollectionViewItem)obj).Title, StringComparison.Ordinal);
+		}
+
+		public override int GetHashCode()
+		{
+			return Title?.GetHashCode(StringComparison.Ordinal) ?? 0;
+		}
+	}
+
+	List<Issue31351CollectionViewItem> CollectionViewItems = new();
+
+	public Issue31351CustomCollectionView()
+	{
+		ItemTemplate = new DataTemplate(() =>
+		{
+			var label = new Label();
+			label.SetBinding(Label.TextProperty, nameof(Issue31351CollectionViewItem.Title));
+			label.Padding = new Thickness(10);
+			label.BackgroundColor = Colors.White;
+
+			var border = new Border
+			{
+				Content = label,
+				BackgroundColor = Colors.White,
+				Stroke = Colors.Gray,
+				StrokeThickness = 1,
+				Margin = new Thickness(2)
+			};
+
+			return border;
+		});
+
+		SelectionMode = SelectionMode.Single;
+
+		InvalidateCommand = new Action(() =>
+		{
+			Invalidate();
+		});
+	}
+
+	void Invalidate()
+	{
+		CollectionViewItems.Clear();
+
+		if (CustomItemsSource != null)
+		{
+			foreach (var itemSource in CustomItemsSource)
+			{
+				CollectionViewItems.Add(new Issue31351CollectionViewItem { Title = itemSource.Title });
+			}
+		}
+
+		ItemsSource = CollectionViewItems;
+		if (CustomSelectedItem != null)
+		{
+			var selectedCollectionViewItem = CollectionViewItems.FirstOrDefault(o => o.Title == CustomSelectedItem.Title);
+
+			ScrollTo(selectedCollectionViewItem, position: ScrollToPosition.Center, animate: true);
+			SelectedItem = selectedCollectionViewItem;
+		}
+
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue31351.cs

@@ -0,0 +1,29 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue31351 : _IssuesUITest
+{
+	public Issue31351(TestDevice testDevice) : base(testDevice)
+	{
+	}
+
+	public override string Issue => "[WinUI] Custom CollectionView does not work on ScrollTo";
+
+	[Test]
+	[Category(UITestCategories.CollectionView)]
+	public void CustomCollectionViewShouldScroll()
+	{
+		App.WaitForElement("Issue31351CollectionView");
+		App.WaitForElement("Issue31351ScrollButton");
+		App.Tap("Issue31351ScrollButton");
+		var MidItemRect = App.WaitForElement("Item 50").GetRect();
+		Assert.That(MidItemRect.X, Is.GreaterThanOrEqualTo(0));
+		App.WaitForElement("Issue31351TopScrollButton");
+		App.Tap("Issue31351TopScrollButton");
+		var TopItemRect = App.WaitForElement("Item 1").GetRect();
+		Assert.That(TopItemRect.X, Is.GreaterThanOrEqualTo(0));
+	}
+}