private int draptype=1;//1：不同级，   不为1：拖同级  private void treeView1_ItemDrag(object sender, ItemDragEventArgs e)        {            if (e.Button == MouseButtons.Left)            {                DoDragDrop(e.Item, DragDropEffects.Move);            }        }        private void treeView1_DragEnter(object sender, DragEventArgs e)        {            if (e.Data.GetDataPresent(typeof(TreeNode)))                e.Effect = DragDropEffects.Move;            else                e.Effect = DragDropEffects.None;        }             private void treeView1_DragDrop(object sender, DragEventArgs e)        {            //获得拖放中的节点            TreeNode moveNode = (TreeNode)e.Data.GetData("System.Windows.Forms.TreeNode");            //根据鼠标坐标确定要移动到的目标节点            Point pt = ((TreeView)sender).PointToClient(new Point(e.X, e.Y));            TreeNode targetNode = treeView1.GetNodeAt(pt);            //如果目标节点为分组则添加到下级节点的未端,如果目标节点为素材文件则添加为同级节点            TreeNode NewMoveNode = (TreeNode)moveNode.Clone();            if (draptype == 1)            {                targetNode.Nodes.Insert(targetNode.Nodes.Count, NewMoveNode);            }            else            {                if (moveNode.NextNode == targetNode)                {                    targetNode.Parent.Nodes.Insert(targetNode.Index + 1, NewMoveNode);                }                else                {                    targetNode.Parent.Nodes.Insert(targetNode.Index, NewMoveNode);                }            }            //更新当前拖动的节点选择            treeView1.SelectedNode = NewMoveNode;            //展开目标节点,便于显示拖放效果            targetNode.Expand();            //移除拖放的节点            moveNode.Remove();                 }