private IHierarchyObject FirstChild(IHierarchyObject item)
{
if (item == null)
{
return(null);
}
return(item.GetAllChildren().FirstOrDefault());
}
private static ItemsControl BringObjectToView(
ItemsControl parentItemsControl,
IHierarchyObject parentDataObject,
IHierarchyObject dataObject)
{
Debug.Assert(parentItemsControl != null);
Debug.Assert(parentDataObject != null);
Debug.Assert(dataObject != null);
// Expand the the tree view item if necessary.
var parentTreeViewItem = parentItemsControl as TreeViewItem;
if (parentTreeViewItem != null)
{
if (!parentTreeViewItem.IsExpanded)
{
// TODO(rpaquay): Use ".IsExpanded = true"?
parentTreeViewItem.SetValue(TreeViewItem.IsExpandedProperty, true);
}
}
// Try to generate the ItemsPresenter and the ItemsPanel. by calling
// ApplyTemplate. Note that in the virtualizing case even if the item is
// marked expanded we still need to do this step in order to regenerate
// the visuals because they may have been virtualized away.
parentItemsControl.ApplyTemplate();
var itemsPresenter = (ItemsPresenter)parentItemsControl.Template.FindName("ItemsHost", parentItemsControl);
if (itemsPresenter != null)
{
itemsPresenter.ApplyTemplate();
}
else
{
// The Tree template has not named the ItemsPresenter,
// so walk the descendents and find the child.
itemsPresenter = FindVisualChild <ItemsPresenter>(parentItemsControl);
if (itemsPresenter == null)
{
parentItemsControl.UpdateLayout();
itemsPresenter = FindVisualChild <ItemsPresenter>(parentItemsControl);
if (itemsPresenter == null)
{
Logger.LogError("Can't find items presenter.");
return(null);
}
}
}
// Access the custom VSP that exposes BringIntoView
var virtualizingStackPanel = VisualTreeHelper.GetChild(itemsPresenter, 0) as VirtualizingStackPanel;
if (virtualizingStackPanel == null)
{
Logger.LogError("Can't find virtual stack panel for parentItemsControl.");
return(null);
}
var dataObjetIndex = parentDataObject.GetAllChildren().IndexOf(dataObject);
if (dataObjetIndex >= parentItemsControl.Items.Count)
{
Logger.LogError("TreeView node has fewer parents than its corresponding data object.");
return(null);
}
virtualizingStackPanel.BringIndexIntoViewPublic(dataObjetIndex);
var treeViewItem = (ItemsControl)parentItemsControl.ItemContainerGenerator.ContainerFromIndex(dataObjetIndex);
if (treeViewItem.DataContext != dataObject)
{
Logger.LogError("TreeView item data context is not the right data object.");
return(null);
}
return(treeViewItem);
}
