protected override void OnKeyUp(KeyEventArgs e)
{
base.OnKeyUp(e);
if (!e.Handled)
{
Key key = e.Key;
switch (key)
{
case Key.Left:
case Key.Right:
case Key.Up:
case Key.Down:
case Key.Add:
case Key.Subtract:
case Key.Space:
IEnumerable <TreeViewItem> items = TreeViewElementFinder.FindAll(ParentTreeView, false);
TreeViewItem focusedItem = items.FirstOrDefault(x => x.IsFocused);
focusedItem?.BringIntoView(new Rect(1, 1, 1, 1));
break;
}
}
}
// TODO: This method has been implemented with a lot of fail and retry, and should be cleaned.
// TODO: Also, it is probably close to work with virtualization, but it needs some testing
public bool BringItemToView(object item, Func <object, object> getParent)
{
// Useful link: https://msdn.microsoft.com/en-us/library/ff407130%28v=vs.110%29.aspx
if (item == null)
{
throw new ArgumentNullException(nameof(item));
}
if (getParent == null)
{
throw new ArgumentNullException(nameof(getParent));
}
if (IsVirtualizing)
{
throw new InvalidOperationException("BringItemToView cannot be used when the tree view is virtualizing.");
}
TreeViewItem container = null;
var path = new List <object> {
item
};
var parent = getParent(item);
while (parent != null)
{
path.Add(parent);
parent = getParent(parent);
}
for (int i = path.Count - 1; i >= 0; --i)
{
if (container != null)
{
container = (TreeViewItem)container.ItemContainerGenerator.ContainerFromItem(path[i]);
}
else
{
container = (TreeViewItem)ItemContainerGenerator.ContainerFromItem(path[i]);
}
if (container == null)
{
return(false);
}
container.IsExpanded = true;
container.ApplyTemplate();
var itemsPresenter = (ItemsPresenter)container.Template.FindName("ItemsHost", container);
if (itemsPresenter == null)
{
// The Tree template has not named the ItemsPresenter,
// so walk the descendents and find the child.
itemsPresenter = container.FindVisualChildOfType <ItemsPresenter>();
if (itemsPresenter == null)
{
container.UpdateLayout();
itemsPresenter = container.FindVisualChildOfType <ItemsPresenter>();
}
}
if (itemsPresenter == null)
{
return(false);
}
itemsPresenter.ApplyTemplate();
var itemsHostPanel = (Panel)VisualTreeHelper.GetChild(itemsPresenter, 0);
itemsHostPanel.UpdateLayout();
itemsHostPanel.ApplyTemplate();
// Ensure that the generator for this panel has been created.
// ReSharper disable once UnusedVariable
UIElementCollection children = itemsHostPanel.Children;
container.BringIntoView();
}
return(true);
}
