Merge pull request #11 from Redth/dev/selecteditems-property

Make SelectedItem/SelectedItems as bindable properties

Sample/VirtualListViewSample/BindableSelectedItemPage.xaml

@@ -0,0 +1,37 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage
+	xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+	xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+	x:Class="VirtualListViewSample.BindableSelectedItemPage"
+	xmlns:local="clr-namespace:VirtualListViewSample"
+	xmlns:vlv="clr-namespace:Microsoft.Maui.Controls;assembly=VirtualListView"
+	x:DataType="local:BindableSelectedItemViewModel"
+	Title="BindableSelectedItemPage">
+	<Grid RowDefinitions="*,Auto" ColumnDefinitions="*,Auto" Padding="20">
+		<vlv:VirtualListView
+			Grid.Row="0"
+			Grid.Column="0" Grid.ColumnSpan="2"
+			x:Name="vlv"
+			Adapter="{Binding Adapter}"
+			SelectedItem="{Binding SelectedItem, Mode=TwoWay}"
+			OnSelectedItemsChanged="vlv_SelectedItemsChanged"
+			SelectionMode="Single">
+			<vlv:VirtualListView.ItemTemplate>
+				<DataTemplate>
+					<vlv:VirtualViewCell SelectedBackground="DarkBlue" UnselectedBackground="LightBlue">
+						<Border
+							Margin="10,0,0,0"
+							Padding="4"
+							Background="Transparent"
+							StrokeShape="{RoundRectangle CornerRadius=10}">
+							<Label Margin="10,6,10,6" Text="{Binding .}" />
+						</Border>
+					</vlv:VirtualViewCell>
+				</DataTemplate>
+			</vlv:VirtualListView.ItemTemplate>
+		</vlv:VirtualListView>
+
+		<Entry x:Name="entryItem" Grid.Row="1" Grid.Column="0" Placeholder="Item" />
+		<Button Grid.Row="1" Grid.Column="1" Text="Select/Deselect" Clicked="Button_Clicked" />
+	</Grid>
+</ContentPage>

Sample/VirtualListViewSample/BindableSelectedItemPage.xaml.cs

@@ -0,0 +1,75 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+using Microsoft.Maui.Adapters;
+using System.Collections.ObjectModel;
+
+namespace VirtualListViewSample;
+
+public partial class BindableSelectedItemViewModel : ObservableObject
+{
+	public BindableSelectedItemViewModel(IDispatcher dispatcher)
+	{
+		Dispatcher = dispatcher;
+
+		for (int i = 0; i < 10; i++)
+		{
+			Items.Add($"Item: {i}");
+		}
+
+		Adapter = new ObservableCollectionAdapter<string>(Items);
+	}
+
+	protected IDispatcher Dispatcher { get; }
+
+	[ObservableProperty]
+	ItemPosition? selectedItem;
+
+	[ObservableProperty]
+	ObservableCollectionAdapter<string> adapter;
+
+	public ObservableCollection<string> Items = new();
+
+	public void OnAppearing()
+	{
+		Task.Delay(1000).ContinueWith(t =>
+		{
+			Dispatcher.Dispatch(() =>
+			{
+				Items.Add("Item 11");
+				Items.Add("Item 12");
+			});
+		});
+	}
+}
+
+public partial class BindableSelectedItemPage : ContentPage
+{
+	public BindableSelectedItemPage()
+	{
+		InitializeComponent();
+
+		ViewModel = new BindableSelectedItemViewModel(Dispatcher);
+
+		BindingContext = ViewModel;
+	}
+
+	public readonly BindableSelectedItemViewModel ViewModel;
+
+	private void Button_Clicked(object sender, EventArgs e)
+	{
+		if (!string.IsNullOrEmpty(entryItem.Text))
+		{
+			var index = ViewModel.Items.IndexOf(entryItem.Text);
+
+			if (index == ViewModel.SelectedItem?.ItemIndex)
+				ViewModel.SelectedItem = null;
+			else if (index >= 0)
+				ViewModel.SelectedItem = new ItemPosition(0, index);
+		}
+	}
+
+	private void vlv_SelectedItemsChanged(object sender, SelectedItemsChangedEventArgs e)
+	{
+		var selection = string.Join(", ", e.NewSelection.Select(i => i.ItemIndex));
+		System.Diagnostics.Debug.WriteLine($"SelectedItemsChanged: {selection}");
+	}
+}

Sample/VirtualListViewSample/MainPage.xaml

@@ -14,6 +14,8 @@
 			<Button Text="Observable Collection Demo" Clicked="Button_Clicked_1" />
 
 			<Button Text="Sectioned Adapter Demo" Clicked="Button_Clicked_2" />
+
+			<Button Text="Bindable Selected Item Demo" Clicked="Button_Clicked_4" />
 		</VerticalStackLayout>
 	</ScrollView>
 </ContentPage>

Sample/VirtualListViewSample/MainPage.xaml.cs

@@ -23,4 +23,9 @@ private void Button_Clicked_2(object sender, EventArgs e)
 	{
 		Navigation.PushAsync(new SectionedAdapterPage());
 	}
+
+	private void Button_Clicked_4(object sender, EventArgs e)
+	{
+		Navigation.PushAsync(new BindableSelectedItemPage());
+	}
 }

Sample/VirtualListViewSample/MainViewModel.cs

@@ -1,27 +1,23 @@
-using CommunityToolkit.Mvvm.Input;
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
 using System.ComponentModel;
 
 namespace VirtualListViewSample;
 
-public partial class MainViewModel : INotifyPropertyChanged
+public partial class MainViewModel : ObservableObject
 {
 	public MainViewModel()
 	{
 		Adapter = new MusicDataAdapter();
 	}
 
-	public MusicDataAdapter Adapter { get; set; }
-
-	public void NotifyPropertyChanged(string propertyName)
-		=> PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
-
-	public event PropertyChangedEventHandler PropertyChanged;
+	[ObservableProperty]
+	MusicDataAdapter adapter;
 
 	[RelayCommand]
 	async Task Refresh()
 	{
 		await Task.Delay(3000);
-		NotifyPropertyChanged(nameof(Adapter));
 	}
 
 	[RelayCommand]

Sample/VirtualListViewSample/MusicLibraryPage.xaml

@@ -23,7 +23,7 @@
 		RefreshCommand="{Binding RefreshCommand}"
 		Adapter="{Binding Adapter}"
 		SelectionMode="Multiple"
-		SelectedItemsChanged="VirtualListView_SelectedItemsChanged"
+		OnSelectedItemsChanged="VirtualListView_SelectedItemsChanged"
 		ItemTemplateSelector="{StaticResource itemTemplateSelector}">
 
 		<vlv:VirtualListView.SectionHeaderTemplate>

Sample/VirtualListViewSample/MusicLibraryPage.xaml.cs

@@ -17,7 +17,9 @@ public MusicLibraryPage()
 		{
 			Dispatcher.Dispatch(() =>
 			{
-				vlv.SelectItems(new ItemPosition(0, 2), new ItemPosition(0, 4));
+				vlv.SelectItem(new ItemPosition(0, 2));
+				vlv.SelectItem(new ItemPosition(0, 4));
+
 			});
 		});
 	}

Sample/VirtualListViewSample/ObservableCollectionPage.xaml

@@ -11,7 +11,7 @@
 			Grid.Row="0"
 			Grid.Column="0" Grid.ColumnSpan="2"
 			x:Name="vlv"
-			SelectedItemsChanged="vlv_SelectedItemsChanged"
+			OnSelectedItemsChanged="vlv_SelectedItemsChanged"
 			SelectionMode="Multiple">
 			<vlv:VirtualListView.EmptyView>
 				<Grid>

Sample/VirtualListViewSample/ObservableCollectionPage.xaml.cs

@@ -47,13 +47,18 @@ private void Button_Clicked(object sender, EventArgs e)
 
 	private void vlv_SelectedItemsChanged(object sender, SelectedItemsChangedEventArgs e)
 	{
-		var item = e.NewSelection?.FirstOrDefault();
+		var selection = string.Join(", ", e.NewSelection.Select(i => i.ItemIndex));
+		System.Diagnostics.Debug.WriteLine($"SelectedItemsChanged: {selection}");
 
-		if (item != null)
+		if (e.NewSelection.Any())
 		{
-			Items.RemoveAt(item.Value.ItemIndex);
-		}
+			var toDelete = e.NewSelection.First();
+
+			vlv.ClearSelectedItems();
 
-		(sender as IVirtualListView).ClearSelection();
+			var item = Adapter.GetItem(toDelete.SectionIndex, toDelete.ItemIndex);
+
+			Items.Remove(item);
+		}
 	}
 }

Sample/VirtualListViewSample/SectionedAdapterPage.xaml

@@ -11,7 +11,7 @@
 			Grid.Row="0"
 			Grid.Column="0" Grid.ColumnSpan="3"
 			x:Name="vlv"
-			SelectedItemsChanged="vlv_SelectedItemsChanged"
+			OnSelectedItemsChanged="vlv_SelectedItemsChanged"
 			SelectionMode="Single">
 			<vlv:VirtualListView.EmptyView>
 				<Label Text="Empty!" HorizontalTextAlignment="Center" VerticalTextAlignment="Center" />

Sample/VirtualListViewSample/SectionedAdapterPage.xaml.cs

@@ -38,13 +38,13 @@ private void Button_Clicked(object sender, EventArgs e)
 
 	private void vlv_SelectedItemsChanged(object sender, SelectedItemsChangedEventArgs e)
 	{
-		var item = e.NewSelection?.FirstOrDefault();
-
-		if (item != null)
+		if (e.NewSelection.Any())
 		{
-			Adapter.RemoveItem(item.Value.SectionIndex, item.Value.ItemIndex);
-		}
+			var item = e.NewSelection.First();
 
-		(sender as IVirtualListView)?.ClearSelection();
+			Adapter.RemoveItem(item.SectionIndex, item.ItemIndex);
+			vlv.ClearSelectedItems();
+		}
+
 	}
 }

Sample/VirtualListViewSample/VirtualListViewSample.csproj

@@ -29,7 +29,7 @@
 	</ItemGroup>
 	<ItemGroup>
 		<PackageReference Include="CommunityToolkit.Mvvm" Version="8.2.1" />
-		<PackageReference Include="LiteDb" Version="5.0.16" />
+		<PackageReference Include="LiteDb" Version="5.0.17" />
 	</ItemGroup>
 	<ItemGroup>
 		<EmbeddedResource Include="chinook.litedb" />

VirtualListView/Apple/CvDataSource.ios.maccatalyst.cs

@@ -13,8 +13,6 @@ public CvDataSource(VirtualListViewHandler handler)
 
 	VirtualListViewHandler Handler { get; }
 
-	public Func<int, int, bool> IsSelectedHandler { get; set; }
-
 	readonly ReusableIdManager itemIdManager = new ReusableIdManager("Item");
 	readonly ReusableIdManager globalIdManager = new ReusableIdManager("Global");
 	readonly ReusableIdManager sectionHeaderIdManager = new ReusableIdManager("SectionHeader", new NSString("SectionHeader"));
@@ -52,7 +50,7 @@ public override UICollectionViewCell GetCell(UICollectionView collectionView, NS
 		if (info.SectionIndex < 0 || info.ItemIndex < 0)
 			info.IsSelected = false;
 		else
-			info.IsSelected = IsSelectedHandler?.Invoke(info.SectionIndex, info.ItemIndex) ?? false;
+			info.IsSelected = Handler?.IsItemSelected(info.SectionIndex, info.ItemIndex) ?? false;
 
 		if (cell.NeedsView)
 		{
@@ -79,9 +77,9 @@ void TapCellHandler(CvCell cell)
 		cell.PositionInfo.IsSelected = !cell.PositionInfo.IsSelected;
 
 		if (cell.PositionInfo.IsSelected)
-			Handler.VirtualView?.SelectItems(p);
+			Handler?.VirtualView?.SelectItem(p);
 		else
-			Handler.VirtualView?.DeselectItems(p);
+			Handler?.VirtualView?.DeselectItem(p);
 	}
 
 	public override nint GetItemsCount(UICollectionView collectionView, nint section)

VirtualListView/Apple/CvDelegate.ios.maccatalyst.cs

@@ -38,9 +38,9 @@ void HandleSelection(UICollectionView collectionView, NSIndexPath indexPath, boo
 				selectedCell.PositionInfo.ItemIndex);
 
 			if (selected)
-				Handler?.VirtualView?.SelectItems(itemPos);
+				Handler?.VirtualView?.SelectItem(itemPos);
 			else
-				Handler?.VirtualView?.DeselectItems(itemPos);
+				Handler?.VirtualView?.DeselectItem(itemPos);
 		}
 	}
 

VirtualListView/Apple/VirtualListViewHandler.ios.maccatalyst.cs

@@ -62,12 +62,10 @@ protected override void ConnectHandler(UICollectionView nativeView)
 		PositionalViewSelector = new PositionalViewSelector(VirtualView);
 
 		dataSource = new CvDataSource(this);
-		dataSource.IsSelectedHandler = (realSection, realIndex) =>
-			VirtualView?.IsItemSelected(realSection, realIndex) ?? false;
-
+
 		cvdelegate = new CvDelegate(this, collectionView);
 		cvdelegate.ScrollHandler = (x, y) =>
-			VirtualView?.Scrolled(new ScrolledEventArgs(x, y));
+			VirtualView?.Scrolled(x, y);
 
 		collectionView.DataSource = dataSource;
 		collectionView.Delegate = cvdelegate;
@@ -117,44 +115,27 @@ public static void MapSelectionMode(VirtualListViewHandler handler, IVirtualList
 	public static void MapInvalidateData(VirtualListViewHandler handler, IVirtualListView virtualListView, object? parameter)
 		=> handler?.InvalidateData();
 
-	public static void MapSelectItems(VirtualListViewHandler handler, IVirtualListView virtualListView, object parameter)
+	void PlatformUpdateItemSelection(ItemPosition itemPosition, bool selected)
 	{
-		if (parameter is ItemPosition[] items)
-		{
-			UpdateSelection(handler, items, true);
-		}
-	}
+		var realIndex = PositionalViewSelector?.GetPosition(itemPosition.SectionIndex, itemPosition.ItemIndex) ?? -1;
 
-	public static void MapDeselectItems(VirtualListViewHandler handler, IVirtualListView virtualListView, object parameter)
-	{
-		if (parameter is ItemPosition[] items)
-		{
-			UpdateSelection(handler, items, false);
-		}
-	}
+		if (realIndex < 0)
+			return;
 
-	static void UpdateSelection(VirtualListViewHandler handler, ItemPosition[] itemPositions, bool selected)
-	{
-		foreach (var itemPosition in itemPositions)
-		{
-			var realIndex = handler.PositionalViewSelector.GetPosition(itemPosition.SectionIndex, itemPosition.ItemIndex);
+		var cell = collectionView.CellForItem(NSIndexPath.FromItemSection(realIndex, 0));
 
-			var cell = handler.collectionView.CellForItem(NSIndexPath.FromItemSection(realIndex, 0));
+		if (cell is CvCell cvcell)
+		{
+			cvcell.PositionInfo.IsSelected = selected;
 
-			if (cell is CvCell cvcell)
+			if (cvcell.VirtualView is IPositionInfo positionInfo)
 			{
-				cvcell.PositionInfo.IsSelected = selected;
-
-				if (cvcell.VirtualView is IPositionInfo positionInfo)
-				{	
-					handler.collectionView.InvokeOnMainThread(() =>
-					{
-						positionInfo.IsSelected = selected;
-					});
-				}
+				collectionView.InvokeOnMainThread(() =>
+				{
+					positionInfo.IsSelected = selected;
+				});
 			}
 		}
-
 	}
 
 	public static void MapOrientation(VirtualListViewHandler handler, IVirtualListView virtualListView)