/// <summary>
/// Returns true if the target node is a valid drop location.
/// For this sample, a valid target node is the one that:
/// Represents an employee (departments are not valid)
/// Is not being copied to the same department it is assigned
/// Is not being moved to a department it is already assigned
/// </summary>
/// <param name="source"></param>
/// <param name="target"></param>
/// <returns></returns>
private bool IsValidDrop(C1TreeViewItem source, C1TreeViewItem target)
{
bool isValidTarget = false;
// For this sample we will allow dragging of employees only
if ((source != null) && (target != null) && (source.Header is Employee) && (target.Header is Employee))
{
// Cannot copy employees in the same department
Employee sourceDataObject = (Employee)source.Header;
bool isAlreadyInDepartment = ((IList)target.ParentItemsSource).Contains(sourceDataObject);
if ((isAlreadyInDepartment) && ((Effect == DragDropEffect.Copy) || (source.Parent != target.Parent)))
{
isValidTarget = false;
}
else
{
isValidTarget = (!source.IsAncestorOf(target) && !(source == target));
}
}
return isValidTarget;
}
