// find the top-level ItemsControl (in a presentation of hierarchical data)
// for the given mid-level container.
// NOTE: This assumes that the only container types are TreeViewItem and
// GroupItem. This is true in 4.5. If hierarchical virtualization
// is ever extended to other container types, this method will need to change.
private ItemsControl GetScrollingItemsControl(UIElement container)
{
if (container is TreeViewItem)
{
ItemsControl parent = ItemsControl.ItemsControlFromItemContainer(container);
while (parent != null)
{
TreeView tv = parent as TreeView;
if (tv != null)
{
return tv;
}
parent = ItemsControl.ItemsControlFromItemContainer(parent);
}
}
else if (container is GroupItem)
{
DependencyObject parent = container;
do
{
parent = VisualTreeHelper.GetParent(parent);
ItemsControl parentItemsControl = parent as ItemsControl;
if (parentItemsControl != null)
{
return parentItemsControl;
}
} while (parent != null);
}
else
{
string name = (container == null) ? "null" : container.GetType().Name;
Debug.Assert(false, "Unexpected container type: " + name);
}
return null;
}