用键盘上下左右键和ctrl键移动TreeView节点

/// <summary>
        /// 用键盘上下左右键和ctrl键移动节点 
        /// 思路:现复制2个选中的节点。1.为了记住第一次选中节点位置，2在上移过程中现将令一个插入指定位置，
        /// 然后将选中节点移除
        /// </summary>
        /// <param name="treeView">treeview</param>
        /// <param name="e">键盘的按键</param>
        private void MoveTreeNodeByKeyWord(TreeView treeView, KeyEventArgs e)
        {
            if (treeView.SelectedNode != null)
            {
                if (e.Control != true) return;

                TreeNode tn = treeView.SelectedNode;
                TreeNode tempNode = (TreeNode)treeView.SelectedNode.Clone();
                switch (e.KeyCode)
                {
                    case Keys.Up:
                        if (treeView.SelectedNode.PrevNode == null)
                            return;

                        if (tn.Parent == null)
                            treeView.Nodes.Insert(tn.Index + 2, tempNode);
                        else
                            tn.Parent.Nodes.Insert(tn.Index + 2, tempNode);

                        treeView.SelectedNode.Remove();
                        treeView.SelectedNode = tempNode;
                        break;
                    case Keys.Down:
                        if (treeView.SelectedNode.NextNode == null)
                            return;

                        if (tn.Parent == null)
                            treeView.Nodes.Insert(tn.Index + 2, tempNode);
                        else
                            tn.Parent.Nodes.Insert(tn.Index + 2, tempNode);

                        treeView.SelectedNode.Remove();
                        treeView.SelectedNode = tempNode;
                        break;
                    case Keys.Left:
                        if (treeView.SelectedNode.Parent == null)
                            return;
                        if (treeView.SelectedNode.Parent.Parent == null)
                            treeView.Nodes.Add(tempNode);
                        else
                            tn.Parent.Parent.Nodes.Add(tempNode);

                        tn.Remove();
                        treeView.SelectedNode = tempNode;
                        break;
                    case Keys.Right:
                        if (treeView.SelectedNode.NextNode == null)
                            return;
                        treeView.SelectedNode.NextNode.Nodes.Insert(0, tempNode);
                        tn.Remove();
                        treeView.SelectedNode = tempNode;
                        break;
                }

            }

        }