/// <summary>Retrieves the first ancestor of a node that still exists as a descendent of the root node.</summary>
/// <param name="root">The root node.</param>
/// <param name="orphan">The orphaned node.</param>
/// <remarks>Useful for when a node is removed, and you want to move a view to the reamining parent.</remarks>
public ITreeNode FirstRemainingParent(ITreeNode root, ITreeNode orphan)
{
if (root == null || orphan == null) return null;
ITreeNode parent = orphan.Parent;
do
{
if (parent == null) break;
if (parent == root || root.ContainsDescendent(parent)) return parent;
parent = parent.Parent;
} while (parent != null);
return null;
}
private static HorizontalEdge GetSlideDirection(ITreeNode previousNode, ITreeNode newNode)
{
if (previousNode == null) return HorizontalEdge.Left;
return previousNode.ContainsDescendent(newNode)
? HorizontalEdge.Left
: HorizontalEdge.Right;
}