Virtualizing an ItemsControl?

Question

I have an ItemsControl containing a list of data that I would like to virtualize, however VirtualizingStackPanel.IsVirtualizing=\"True\" does not s

Answer 1

There's actually much more to it than just making the ItemsPanelTemplate use VirtualizingStackPanel. The default ControlTemplate for ItemsControl does not have a ScrollViewer, which is the key to virtualization. Adding to the the default control template for ItemsControl (using the control template for ListBox as a template) gives us the following:

(BTW, a great tool for looking at default control templates is Show Me The Template)

Things to notice:

You have to set ScrollViewer.CanContentScroll="True", see here for why.

Also notice that I put VirtualizingStackPanel.VirtualizationMode="Recycling". This will reduce the numbers of times TextBlock_Initialized is called to however many TextBlocks are visible on the screen. You can read more on UI virtualization here .

EDIT: Forgot to state the obvious: as an alternate solution, you can just replace ItemsControl with ListBox :) Also, check out this Optimizing Performance on MSDN page and notice that ItemsControl isn't in the "Controls That Implement Performance Features" table, which is why we need to edit the control template.