/// <summary>
/// Raises the <see cref="UIElement.KeyDown"/> event.
/// </summary>
/// <param name="e">
/// The <see cref="KeyEventArgs"/> instance containing the event data.
/// </param>
protected override void OnKeyDown(KeyEventArgs e)
{
if (e == null)
{
throw new ArgumentNullException(nameof(e));
}
base.OnKeyDown(e);
if (e.Handled)
{
return;
}
// TODO: Consider FlowDirection for Left/Right.
switch (e.Key)
{
case Key.Left:
case Key.Subtract:
if (CanExpand && IsEnabled && IsExpanded)
{
e.Handled = true;
IsExpanded = false;
}
break;
case Key.Add:
case Key.Right:
if (CanExpand && IsEnabled && !IsExpanded)
{
e.Handled = true;
IsExpanded = true;
}
break;
}
if (!e.Handled)
{
ParentTreeView?.HandleKeyDown(this, e);
}
}