fixed virtualization issues with uno apps

Author: w-ahmad

src/TableView.cs

@@ -1336,6 +1336,16 @@ private void EnsureCellsStyle()
         }
     }
 
+#if !WINDOWS
+    internal void EnsureCells()
+    {
+        foreach (var row in _rows)
+        {
+            row.EnsureCells();
+        }
+    } 
+#endif
+
 #if WINDOWS
     /// <summary>
     /// Shows the context flyout for the specified row.

src/TableViewCell.cs

@@ -56,29 +56,14 @@ private void OnContextRequested(UIElement sender, ContextRequestedEventArgs args
     }
 #endif
 
-#if !WINDOWS
-    protected override void OnDataContextChanged()
-    {
-        base.OnDataContextChanged();
-
-        if (DataContext is TableViewColumn column)
-        {
-            Column = column;
-            Width = column.ActualWidth;
-            Style = column.CellStyle ?? TableView?.CellStyle;
-        }
-    }
-#endif
 
     /// <summary>
     /// Handles the Loaded event.
     /// </summary>
     private void OnLoaded(object sender, RoutedEventArgs e)
     {
-#if WINDOWS
         InvalidateMeasure();
         ApplySelectionState();
-#endif
     }
 
     protected override void OnApplyTemplate()
@@ -89,23 +74,7 @@ protected override void OnApplyTemplate()
         _selectionBorder = GetTemplateChild("SelectionBorder") as Border;
         _v_gridLine = GetTemplateChild("VerticalGridLine") as Rectangle;
 
-#if WINDOWS
         EnsureGridLines();
-#else
-        if (this.FindAscendant<TableViewRow>() is { TableView: { } } row)
-        {
-            Row = row;
-            TableView = row.TableView;
-            Index = Column is not null ? TableView.Columns.VisibleColumns.IndexOf(Column) : -1;
-            DataContext = Row?.Content;
-
-            EnsureGridLines();
-            SetElement();
-
-            InvalidateMeasure();
-            ApplySelectionState();
-        }
-#endif
     }
 
     protected override Size MeasureOverride(Size availableSize)
@@ -342,10 +311,6 @@ internal async void PrepareForEdit()
     /// </summary>
     internal void SetElement()
     {
-#if !WINDOWS
-        if (_contentPresenter is null) return; 
-#endif
-
         var element = Column?.GenerateElement(this, Row?.Content);
 
         if (element is not null && Column is TableViewBoundColumn { ElementStyle: { } } boundColumn)

src/TableViewCellsPresenter.cs

@@ -15,7 +15,6 @@ namespace WinUI.TableView;
 public partial class TableViewCellsPresenter : Control
 {
     private StackPanel? _stackPanel;
-    private ItemsControl? _itemsControl;
     private Rectangle? _v_gridLine;
     private Rectangle? _h_gridLine;
 
@@ -32,21 +31,15 @@ protected override void OnApplyTemplate()
         base.OnApplyTemplate();
 
         _stackPanel = GetTemplateChild("StackPanel") as StackPanel;
-        _itemsControl = GetTemplateChild("ItemsControl") as ItemsControl;
         _v_gridLine = GetTemplateChild("VerticalGridLine") as Rectangle;
         _h_gridLine = GetTemplateChild("HorizontalGridLine") as Rectangle;
 
         TableViewRow = this.FindAscendant<TableViewRow>();
         TableView = TableViewRow?.TableView;
 
 #if !WINDOWS
-        if (_itemsControl is not null)
-        {
-            _itemsControl.Visibility = Visibility.Visible;
-            _itemsControl.ItemsSource = TableView?.Columns.VisibleColumns;
-        }
+        TableView?.EnsureCells();  
 #endif
-
         EnsureGridLines();
     }
 
@@ -89,13 +82,7 @@ internal void EnsureGridLines()
     /// <summary>
     /// Gets the list of cells in the presenter.
     /// </summary>
-    public IList<TableViewCell> Cells =>
-
-#if WINDOWS
-        _stackPanel?.Children.OfType<TableViewCell>().ToList()!;
-#else
-        _itemsControl?.FindDescendants().OfType<TableViewCell>().ToList()!;
-#endif
+    public IList<TableViewCell> Cells => _stackPanel?.Children.OfType<TableViewCell>().ToList()!;
 
     /// <summary>
     /// Gets or sets the TableViewRow associated with the presenter.

src/TableViewRow.cs

@@ -227,27 +227,25 @@ protected override void OnTapped(TappedRoutedEventArgs e)
         }
     }
 
-#if WINDOWS
     /// <summary>
     /// Ensures cells are created for the row.
     /// </summary>
-    private void EnsureCells()
+    internal void EnsureCells()
     {
         if (TableView is null)
         {
             return;
         }
 
-        if (CellPresenter is not null)
+        if (CellPresenter is { Children: { } } && (_ensureCells || _cellPresenter != CellPresenter))
         {
+            _cellPresenter = CellPresenter;
             CellPresenter.Children.Clear();
 
             AddCells(TableView.Columns.VisibleColumns);
-        }
-
         _ensureCells = false;
     } 
-#endif
+    }
 
     /// <summary>
     /// Handles the SizeChanged event.
@@ -561,20 +559,10 @@ internal set
         }
     }
 
-    public TableViewCellsPresenter? CellPresenter
-    {
-        get
-        {
-            if (_cellPresenter is null)
-            {
+    public TableViewCellsPresenter? CellPresenter =>
 #if WINDOWS
-                _cellPresenter = ContentTemplateRoot as TableViewCellsPresenter; 
+            ContentTemplateRoot as TableViewCellsPresenter; 
 #else
-                _cellPresenter = this.FindDescendant<TableViewCellsPresenter>();
+            this.FindDescendant<TableViewCellsPresenter>();
 #endif
-            }
-
-            return _cellPresenter;
-        }
-    }
 }

src/Themes/TableViewCellsPresenter.xaml

@@ -22,24 +22,15 @@
                                 <ColumnDefinition Width="Auto" />
                                 <ColumnDefinition Width="*" />
                             </Grid.ColumnDefinitions>
+
                             <StackPanel x:Name="StackPanel"
                                         Grid.Column="1"
-                                        Orientation="Horizontal" />
-
-                            <ItemsControl x:Name="ItemsControl"
-                                          Grid.Column="1"
-                                          Visibility="Collapsed">
-                                <ItemsControl.ItemsPanel>
-                                    <ItemsPanelTemplate>
-                                        <StackPanel Orientation="Horizontal" />
-                                    </ItemsPanelTemplate>
-                                </ItemsControl.ItemsPanel>
-                                <ItemsControl.ItemTemplate>
-                                    <DataTemplate>
-                                        <local:TableViewCell />
-                                    </DataTemplate>
-                                </ItemsControl.ItemTemplate>
-                            </ItemsControl>
+                                        Orientation="Horizontal">
+                                <!--This is just dummy textblock. It would be removed at runtime-->
+                                <TextBlock Margin="16,0"
+                                           Text="{Binding}" 
+                                           VerticalAlignment="Center" />
+                            </StackPanel>
 
                             <Rectangle x:Name="VerticalGridLine"
                                        Width="1"