fix(listview): [WASM] [Skia] Redraw list when scroll viewport changes

Fixes bug where materialized elements would not be added to list when its size changes.

src/Uno.UI.RuntimeTests/Tests/Windows_UI_Xaml_Controls/Given_ListViewBase.cs

@@ -1705,8 +1705,42 @@ void RemoveItem()
 			}
 		}
 
+		[TestMethod]
+		public async Task When_List_Given_More_Space()
+		{
+
+			var list = new ListView
+			{
+				ItemsPanel = NoCacheItemsStackPanel,
+				ItemTemplate = FixedSizeItemTemplate,
+				ItemContainerStyle = NoSpaceContainerStyle,
+				ItemsSource = Enumerable.Range(0,10).Select(i => $"Item {i}").ToArray()
+			};
+			var host = new Grid
+			{
+				Height = 100,
+				Children =
+				{
+					list
+				}
+			};
+
+			WindowHelper.WindowContent = host;
+			await WindowHelper.WaitForLoaded(list);
+
+			Assert.IsNotNull(list.ContainerFromIndex(2));
+			Assert.IsNull(list.ContainerFromIndex(8));
+
+			host.Height = 300;
+
+			await WindowHelper.WaitForNonNull(() => list.ContainerFromIndex(8));
+		}
+
 		private bool ApproxEquals(double value1, double value2) => Math.Abs(value1 - value2) <= 2;
 
+
+
+		#region Helper classes
 		private class When_Removed_From_Tree_And_Selection_TwoWay_Bound_DataContext : System.ComponentModel.INotifyPropertyChanged
 		{
 			public event System.ComponentModel.PropertyChangedEventHandler PropertyChanged;
@@ -1951,4 +1985,5 @@ protected override DataTemplate SelectTemplateCore(object item)
 			}
 		}
 	}
+	#endregion
 }

src/Uno.UI/UI/Xaml/Controls/ListViewBase/VirtualizingPanelLayout.managed.cs

@@ -190,6 +190,7 @@ private void OnLoaded(object sender, RoutedEventArgs e)
 				{
 					ScrollViewer = scrollViewer;
 					ScrollViewer.ViewChanged += OnScrollChanged;
+					ScrollViewer.SizeChanged += OnScrollViewerSizeChanged;
 				}
 				else if (parent is ItemsControl itemsControl)
 				{
@@ -222,6 +223,7 @@ private void OnUnloaded(object sender, RoutedEventArgs e)
 			if (ScrollViewer != null)
 			{
 				ScrollViewer.ViewChanged -= OnScrollChanged;
+				ScrollViewer.SizeChanged -= OnScrollViewerSizeChanged;
 			}
 
 			ScrollViewer = null;
@@ -264,6 +266,11 @@ private void OnScrollChanged(object? sender, ScrollViewerViewChangedEventArgs e)
 			_lastScrollOffset = ScrollOffset;
 		}
 
+		private void OnScrollViewerSizeChanged(object sender, SizeChangedEventArgs args)
+		{
+			OwnerPanel?.InvalidateMeasure();
+		}
+
 		/// <summary>
 		/// Get the increment to consume scroll changes, based on the size of the disappearing view.
 		/// </summary>