WPF ComboBox performance problems by binding a large collections

Question

I\'m trying to bind a large collection to a ComboBox and I faced performance problems when opening ComboBox\'s popup. I searched internet and found that using VirtualizingSt

Answer 1

I had the issue with slow performance as well. But I had created a class that inherited form Combobox, therefor I would like to do this programmatically. So here is that solution for other googlers out there.

ItemsPanel = new ItemsPanelTemplate();
var stackPanelTemplate = new FrameworkElementFactory(typeof (VirtualizingStackPanel));
ItemsPanel.VisualTree = stackPanelTemplate;

Answer 2

According to this blog: http://vbcity.com/blogs/xtab/archive/2009/12/15/wpf-using-a-virtualizingstackpanel-to-improve-combobox-performance.aspx

I've tested it with this code:

<ComboBox Name="cbBlah" ItemsSource="{Binding}">
    <ComboBox.ItemsPanel>
        <ItemsPanelTemplate>
            <VirtualizingStackPanel />
        </ItemsPanelTemplate>
    </ComboBox.ItemsPanel>
</ComboBox>

It works fine for first time and next times. It's not necessary to code these lines:

<VirtualizingStackPanel VirtualizingStackPanel.IsVirtualizing="True" VirtualizingStackPanel.VirtualizationMode="Recycling" />

I hope this helps you.

Answer 3

I just ran into this issue as well. I'm using this code in a custom combo box with a style template. When I ran my code in VS debugging mode the virtualization did not work properly. Once I ran it outside of debugging I can switch the content of the ObservableCollection without locking the UI up. It also might help if you set a max height and max width.

<Setter Property="ScrollViewer.CanContentScroll" Value="True"/> 
<Setter Property="VirtualizingStackPanel.IsVirtualizing" Value="True"/>
<Setter Property="VirtualizingStackPanel.VirtualizationMode" Value="Recycling"/>

<Popup>
    <Border/>
    <ScrollViewer>
      <VirtualizingStackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Contained"/>
    </ScrollViewer> 
  </Grid>
</Popup>