feat: AutoLoad on DataContext changed to support DataGrid

Author: Chaoses-Ib

DataVirtualization/VirtualListItemBase.cs

@@ -15,15 +15,19 @@ public abstract class VirtualListItemBase
 
         static void OnAutoLoadChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
         {
-            DependencyPropertyDescriptor dpd = DependencyPropertyDescriptor.FromProperty(ContentControl.ContentProperty, typeof(DependencyObject));
+            // DataGridRow is not ContentControl
+            //DependencyPropertyDescriptor dpd = DependencyPropertyDescriptor.FromProperty(ContentControl.ContentProperty), typeof(DependencyObject));
+            DependencyPropertyDescriptor dpd = DependencyPropertyDescriptor.FromProperty(FrameworkElement.DataContextProperty, typeof(DependencyObject));
             if (dpd == null)
+            {
                 return;
+            }
 
             bool isEnabled = (bool)e.NewValue;
             if (isEnabled)
-                dpd.AddValueChanged(d, OnContentChanged);
+                dpd.AddValueChanged(d, OnDataContextChanged);
             else
-                dpd.RemoveValueChanged(d, OnContentChanged);
+                dpd.RemoveValueChanged(d, OnDataContextChanged);
         }
 
         static void OnContentChanged(object sender, EventArgs e)
@@ -33,6 +37,13 @@ static void OnContentChanged(object sender, EventArgs e)
                 item.LoadAsync();
         }
 
+        static void OnDataContextChanged(object sender, EventArgs e)
+        {
+            VirtualListItemBase item = ((DependencyObject)sender).GetValue(FrameworkElement.DataContextProperty) as VirtualListItemBase;
+            if (item != null)
+                item.LoadAsync();
+        }
+
         public static bool GetAutoLoad(DependencyObject d)
         {
             return (bool)d.GetValue(AutoLoadProperty);

DataVirtualizationDemo/Window1.xaml

@@ -10,10 +10,14 @@
             <TextBlock Text="{Binding FirstName}" />
         </DataTemplate>
 
-        <!-- Setting VirtualListItemBase.AutoLoad to true will load the item when it's set to ListViewItem.Content property -->
+        <!-- Setting VirtualListItemBase.AutoLoad to true will load the item when it's set to ListViewItem.DataContext property -->
         <Style TargetType="ListViewItem">
             <Setter Property="dz:VirtualListItemBase.AutoLoad" Value="true" />
         </Style>
+        <!-- Setting VirtualListItemBase.AutoLoad to true will load the item when it's set to DataGridRow.DataContext property -->
+        <Style TargetType="DataGridRow">
+            <Setter Property="dz:VirtualListItemBase.AutoLoad" Value="true" />
+        </Style>
 
         <!-- ColumnHeader template to show up and down arrow when sorted -->
         <DataTemplate x:Key="ListViewColumnHeaderTemplate">
@@ -80,6 +84,26 @@
                 </GridView>
             </ListView.View>
         </ListView>
+
+        <DataGrid
+            x:Name="dataGrid"
+            EnableRowVirtualization="True"
+            ScrollViewer.IsDeferredScrollingEnabled="True"
+            dz:VirtualListLoadingIndicator.IsAttached="True"
+            Height="200">
+            <DataGrid.Columns>
+               <DataGridTextColumn Width="60" Binding="{Binding Data.Id}" Header="Id" SortMemberPath="Id" />
+                <DataGridTextColumn Width="120" Binding="{Binding Data.FirstName}" Header="First Name" SortMemberPath="FirstName" />
+                <DataGridTextColumn Width="120" Binding="{Binding Data.LastName}" Header="Last Name" SortMemberPath="LastName" />
+                <DataGridTemplateColumn Width="100" Header="DataTemplate test">
+                    <DataGridTemplateColumn.CellTemplate>
+                        <DataTemplate>
+                            <ContentControl Content="{Binding Data}" />
+                        </DataTemplate>
+                    </DataGridTemplateColumn.CellTemplate>
+                </DataGridTemplateColumn>
+            </DataGrid.Columns>
+        </DataGrid>
 
         <TextBlock>
             <Hyperlink NavigateUri="http://www.devzest.com/blog/post/WPF-Data-Virtualization.aspx" Click="Hyperlink_Click">http://www.devzest.com/blog/post/WPF-Data-Virtualization.aspx</Hyperlink>

DataVirtualizationDemo/Window1.xaml.cs

@@ -75,6 +75,7 @@ private void Refresh_Click(object sender, RoutedEventArgs e)
         {
             VirtualList<Person> data = new VirtualList<Person>(this);
             listView.ItemsSource = data;
+            dataGrid.ItemsSource = data;
         }
 
         // This method helps to get dependency property value in another thread.