WPF Listbox Virtualization - How to Bring Item Into View

Question

I've got a listbox where I have to have virtualization on. I then have a map that has items plotted on it that need to have the feature of letting the user click on them. When they click on an item, I need to bring that item into view in the listbox.

The issue is virtualization. When I try to grab the container, it returns null, which makes sense, however what's the right thing to do? I've tried a few things such as UpdateLayout(), but I've yet to find the answer. Any ideas?

var container = lstItems.ItemContainerGenerator.ContainerFromItem(clickedItem);
if (container != null)
{
     var exp = container.Descendants().OfType<Expander>().FirstOrDefault();
     if (exp != null)
     {
          exp.IsExpanded = true;
          exp.BringIntoView();
     }
}

Answer 1

ListBox为您提供了完成此操作的方法：

lstItems.ScrollIntoView(clickedItem);

如果您在已经展示的代码上方插入该行，那么container应该会为您提供实际的ListBoxItem。

但是，如果该项目不在视图范围内，则可能尚未应用该模板。您可以在搜索container.UpdateLayout()之前致电Expander来解决此问题。

但是，你仍然需要exp.BringIntoView()调用，因为扩展器在扩展后可能会变得更大，并且对ScrollIntoView的初始调用可能没有将它带到视口中。或者，您可以再次拨打ScrollIntoView。