Start working on animations for insert/delete from list

Sample/VirtualListViewSample/ObservableCollectionPage.xaml.cs

@@ -57,8 +57,8 @@ private void vlv_SelectedItemsChanged(object sender, SelectedItemsChangedEventAr
 			vlv.ClearSelectedItems();
 
 			var item = Adapter.GetItem(toDelete.SectionIndex, toDelete.ItemIndex);
-
 			Items.Remove(item);
+			this.vlv.DeleteItems(new []{ new ItemPosition(toDelete.SectionIndex, toDelete.ItemIndex)});
 		}
 	}
 

Sample/VirtualListViewSample/Section.cs

@@ -1,6 +1,12 @@
 namespace VirtualListViewSample;
 
-public class Section : List<string>
+public class Section : List<Item>
 {
 	public string Title { get; set; }
 }
+
+public class Item
+{
+	public string Text { get; set; }
+	public double Height { get; set; }
+}

Sample/VirtualListViewSample/SectionedAdapter.cs

@@ -2,7 +2,7 @@
 
 namespace VirtualListViewSample;
 
-public class SectionedAdapter : VirtualListViewAdapterBase<Section, string>
+public class SectionedAdapter : VirtualListViewAdapterBase<Section, Item>
 {
 	public SectionedAdapter(IList<Section> items) : base()
 	{
@@ -18,23 +18,41 @@ public override int GetNumberOfSections()
 		=> Items.Count;
 
 	public override int GetNumberOfItemsInSection(int sectionIndex)
-		=> Items[sectionIndex].Count;
+	{
+		var c = Items[sectionIndex].Count;
+		Console.WriteLine($"GetNumberOfItemsInSection: section={sectionIndex}, count={c}");
+		return c;
+	}
 
-	public override string GetItem(int sectionIndex, int itemIndex)
+	public override Item GetItem(int sectionIndex, int itemIndex)
 		=> Items[sectionIndex][itemIndex];
 
-	public void AddItem(string sectionTitle, string itemName)
+	public ItemPosition AddItem(string sectionTitle, string itemName, double itemHeight = 40f)
 	{
-		var section = Items.FirstOrDefault(s => s.Title == sectionTitle);
-
+		Section section = null;
+		var sectionIndex = -1;
+
+		for (var s = 0; s < Items.Count; s++)
+		{
+			if (Items[s].Title == sectionTitle)
+			{
+				section = Items[s];
+				sectionIndex = s;
+				break;
+			}
+		}
+
 		if (section is null)
 		{
 			section = new Section { Title = sectionTitle };
 			Items.Add(section);
+			sectionIndex = Items.Count - 1;
 		}
 
-		section.Add(itemName);
+		section.Add(new Item { Text = itemName, Height = itemHeight });
 		InvalidateData();
+
+		return new ItemPosition(sectionIndex, section.Count - 1);
 	}
 
 	public void RemoveItem(int sectionIndex, int itemIndex)

Sample/VirtualListViewSample/SectionedAdapterPage.xaml

@@ -6,7 +6,7 @@
 	xmlns:local="clr-namespace:VirtualListViewSample"
 	xmlns:vlv="clr-namespace:Microsoft.Maui.Controls;assembly=VirtualListView"
 	Title="SectionedAdapterPage">
-	<Grid RowDefinitions="*,Auto" ColumnDefinitions="*,*,Auto" Padding="20">
+	<Grid RowDefinitions="*,Auto,Auto" ColumnDefinitions="*,*,Auto" Padding="20">
 		<vlv:VirtualListView
 			Grid.Row="0"
 			Grid.Column="0" Grid.ColumnSpan="3"
@@ -32,15 +32,17 @@
 					Margin="10,0,0,0"
 					Padding="4"
 					Background="LightBlue"
+					HeightRequest="{Binding Height}"
 					StrokeShape="{RoundRectangle CornerRadius=10}">
-						<Label Margin="10,6,10,6" Text="{Binding .}" />
+						<Label Margin="10,6,10,6" Text="{Binding Text}" />
 					</Border>
 				</DataTemplate>
 			</vlv:VirtualListView.ItemTemplate>
 		</vlv:VirtualListView>
 
 		<Entry x:Name="entrySection" Grid.Row="1" Grid.Column="0" Placeholder="Section" />
 		<Entry x:Name="entryItem" Grid.Row="1" Grid.Column="1" Placeholder="Item" />
-		<Button Grid.Row="1" Grid.Column="3" Text="Add" Clicked="Button_Clicked" />
+		<Entry x:Name="entryItemSize" Grid.Row="2" Grid.Column="0" Placeholder="Item Size" />
+		<Button Grid.Row="1" Grid.RowSpan="2" Grid.Column="3" Text="Add" Clicked="Button_Clicked" />
 	</Grid>
 </ContentPage>

Sample/VirtualListViewSample/SectionedAdapterPage.xaml.cs

@@ -31,8 +31,23 @@ private void Button_Clicked(object sender, EventArgs e)
 	{
 		if (!string.IsNullOrEmpty(entrySection.Text) && !string.IsNullOrEmpty(entryItem.Text))
 		{
-			Adapter.AddItem(entrySection.Text, entryItem.Text);
-			entryItem.Text = string.Empty;
+#if IOS || MACCATALYST
+			if (vlv.Handler.PlatformView is UIKit.UICollectionView cv && vlv.Handler is VirtualListViewHandler vlvHandler)
+			{
+				var h = 40;
+				if (int.TryParse(entryItemSize.Text, out var p))
+					h = p;
+
+				var itemPosition = Adapter.AddItem(entrySection.Text, entryItem.Text, h);
+				Adapter.InvalidateData();
+
+				var indexPath = Foundation.NSIndexPath.FromItemSection(vlvHandler.PositionalViewSelector.GetPosition(itemPosition.SectionIndex, itemPosition.ItemIndex), 0);
+
+				cv.InsertItems(new []{ indexPath });
+
+				entryItem.Text = string.Empty;
+			}
+			#endif
 		}
 	}
 
@@ -42,7 +57,17 @@ private void vlv_SelectedItemsChanged(object sender, SelectedItemsChangedEventAr
 		{
 			var item = e.NewSelection.First();
 
-			Adapter.RemoveItem(item.SectionIndex, item.ItemIndex);
+			#if IOS || MACCATALYST
+			if (vlv.Handler.PlatformView is UIKit.UICollectionView cv && vlv.Handler is VirtualListViewHandler vlvHandler)
+			{
+				var indexPath = Foundation.NSIndexPath.FromItemSection(vlvHandler.PositionalViewSelector.GetPosition(item.SectionIndex, item.ItemIndex), 0);
+				Adapter.RemoveItem(item.SectionIndex, item.ItemIndex);
+				Adapter.InvalidateData();
+
+				cv.DeleteItems(new []{ indexPath });
+			}
+			#endif
+			//vlv.DeleteItems(new [] { new ItemPosition(item.SectionIndex, item.ItemIndex)});
 			vlv.ClearSelectedItems();
 		}
 

VirtualListView/Adapters/IVirtualListViewAdapter.cs

@@ -10,7 +10,5 @@ public interface IVirtualListViewAdapter
 
 	object GetItem(int sectionIndex, int itemIndex);
 
-	event EventHandler OnDataInvalidated;
-
 	void InvalidateData();
 }

VirtualListView/Adapters/VirtualListViewAdapterBase.cs

@@ -4,11 +4,8 @@ public abstract class VirtualListViewAdapterBase<TSection, TItem> : IVirtualList
 {
 	public virtual int GetNumberOfSections() => 1;
 
-	public event EventHandler OnDataInvalidated;
-
 	public virtual void InvalidateData()
 	{
-		OnDataInvalidated?.Invoke(this, EventArgs.Empty);
 	}
 
 	public abstract TItem GetItem(int sectionIndex, int itemIndex);

VirtualListView/Apple/CvDataSource.ios.maccatalyst.cs

@@ -87,6 +87,9 @@ void TapCellHandler(CvCell cell)
 
 	public override nint GetItemsCount(UICollectionView collectionView, nint section)
 	{
-		return Handler?.PositionalViewSelector?.TotalCount ?? 0;
+		var c = Handler?.PositionalViewSelector?.TotalCount ?? 0;
+
+		Console.WriteLine($"GetItemsCount: section={section}, count={c}");
+		return c;
 	}
 }

VirtualListView/Apple/VirtualListViewHandler.ios.maccatalyst.cs

@@ -107,22 +107,6 @@ protected override void DisconnectHandler(UICollectionView nativeView)
 	internal CvCell? GetCell(NSIndexPath indexPath)
 		=> dataSource?.GetCell(PlatformView, indexPath) as CvCell;
 
-	public static void MapHeader(VirtualListViewHandler handler, IVirtualListView virtualListView)
-		=> handler?.InvalidateData();
-
-	public static void MapFooter(VirtualListViewHandler handler, IVirtualListView virtualListView)
-		=> handler?.InvalidateData();
-
-	public static void MapViewSelector(VirtualListViewHandler handler, IVirtualListView virtualListView)
-		=> handler?.InvalidateData();
-
-	public static void MapSelectionMode(VirtualListViewHandler handler, IVirtualListView virtualListView)
-	{
-	}
-
-	public static void MapInvalidateData(VirtualListViewHandler handler, IVirtualListView virtualListView, object? parameter)
-		=> handler?.InvalidateData();
-
 	void PlatformScrollToItem(ItemPosition itemPosition, bool animated)
 	{
 		var realIndex = PositionalViewSelector?.GetPosition(itemPosition.SectionIndex, itemPosition.ItemIndex) ?? -1;
@@ -134,6 +118,64 @@ void PlatformScrollToItem(ItemPosition itemPosition, bool animated)
 
 		PlatformView.ScrollToItem(indexPath, UICollectionViewScrollPosition.Top, animated);
 	}
+
+	public void PlatformDeleteItems(ItemPosition[] itemPositions)
+	{
+		var realIndexes = itemPositions.Select(p => PositionalViewSelector.GetPosition(p.SectionIndex, p.ItemIndex));
+
+		PlatformView.InvokeOnMainThread(() =>
+		{
+			try
+			{
+				var ristr = string.Join(", ", realIndexes);
+
+				Console.WriteLine("ReloadData");
+				PlatformView.ReloadData();
+
+				var nsindexes = realIndexes.Select(r => NSIndexPath.FromItemSection(new nint(r), new nint(0))).ToArray();
+
+				Console.WriteLine($"DeleteItems: {ristr}");
+				PlatformView.DeleteItems(nsindexes);
+			}
+			catch (Exception ex)
+			{
+				Console.WriteLine("ERROR: " + ex);
+			}
+		});
+	}
+
+	public void PlatformDeleteSection(int sectionIndex)
+	{
+	}
+
+	public void PlatformInsertItems(ItemPosition[] itemPositions)
+	{
+		var realIndexes = itemPositions.Select(p => PositionalViewSelector.GetPosition(p.SectionIndex, p.ItemIndex));
+
+		PlatformView.InvokeOnMainThread(() =>
+		{
+			try
+			{
+				var ristr = string.Join(", ", realIndexes);
+
+				Console.WriteLine("ReloadData");
+				PlatformView.ReloadData();
+
+				var nsindexes = realIndexes.Select(r => NSIndexPath.FromItemSection(new nint(r), new nint(0))).ToArray();
+
+				Console.WriteLine($"InsertItems: {ristr}");
+				PlatformView.InsertItems(nsindexes);
+			}
+			catch (Exception ex)
+			{
+				Console.WriteLine("ERROR: " + ex);
+			}
+		});
+	}
+
+	public void PlatformInsertSection(int sectionIndex)
+	{
+	}
 
 	void PlatformUpdateItemSelection(ItemPosition itemPosition, bool selected)
 	{
@@ -165,7 +207,7 @@ public static void MapOrientation(VirtualListViewHandler handler, IVirtualListVi
 			};
 		}
 
-		handler.InvalidateData();
+		handler.PlatformInvalidateData();
 	}
 
 	public static void MapRefreshAccentColor(VirtualListViewHandler handler, IVirtualListView virtualListView)
@@ -213,9 +255,9 @@ void UpdateEmptyView()
 		}
 	}
 
-	public void InvalidateData()
+	void PlatformInvalidateData()
 	{
-		this.PlatformView.InvokeOnMainThread(() => {
+		this.PlatformView.InvokeOnMainThread(() => { 
 			layout?.InvalidateLayout();
 
 			UpdateEmptyViewVisibility();