TreeView拖放

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication7
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
  
       
        //保存前一个鼠标进入的节点
        private TreeNode MyOldNode;

        private void Form1_Load_1(object sender, EventArgs e)
        {
             //添加树形视图子节点
        this.treeView1.Nodes.AddRange(
             new TreeNode[]
             {
                 new TreeNode("中国直辖市", new TreeNode[]
                 {
                    new TreeNode("北京市", new TreeNode[]
                    {
                        new TreeNode("东城区"), new TreeNode("西城区"),new TreeNode("朝阳区")
                    }),
                    new TreeNode("上海市", new TreeNode[]
                    {
                        new TreeNode("长宁区"),new TreeNode("黄埔区"), new TreeNode("浦东区")
                    }),
                    new TreeNode("重庆市", new TreeNode[]
                    {
                        new TreeNode("长寿区", new TreeNode[]
                        {
                            new TreeNode("云台镇"),
                            new TreeNode("凤城镇", new TreeNode[]
                            {
                                new TreeNode("黄桷湾"),new TreeNode("关口")
                            })
                        }),
                        new TreeNode("渝北区"),new TreeNode("北碚区")
                    })
                 })
             });
             this.treeView1.AllowDrop = true;
             this.treeView1.ExpandAll();
        }

        private void treeView1_DragEnter_1(object sender, DragEventArgs e)
        {
            //处理 treeView1控件DragEnter事件
            //获取节点的数据内容
            object MyData = e.Data.GetData(typeof(TreeNode));
            //如果节点有数据，拖放目标允许移动
            if (MyData != null)
            {
                e.Effect = DragDropEffects.Move;
            }
            else
            {
                e.Effect = DragDropEffects.None;
            }

            TreeView MyTreeView = (TreeView)sender;
            TreeNode MyNode = MyTreeView.GetNodeAt(treeView1.PointToClient(new Point(e.X, e.Y)));
            if (MyNode != null)
            {
                //改变进入节点的背景色
                MyNode.BackColor = Color.Blue;
                //保存此节点，进入下一个时还原背景色
                MyOldNode = MyNode;
            }
        }

        private void treeView1_DragOver_1(object sender, DragEventArgs e)
        {
            //处理 treeView1控件DragOver事件
            //修改鼠标进入节点的背景色，还原上一个节点的背景色
            TreeView MyTreeView = (TreeView)sender;
            TreeNode MyNode = MyTreeView.GetNodeAt(treeView1.PointToClient(new Point(e.X, e.Y)));
            if ((MyNode != null) && (MyNode != MyOldNode))
            {
                MyOldNode.BackColor = Color.White;
                MyNode.BackColor = Color.Blue;
                MyOldNode = MyNode;
            }
        }

        private void treeView1_DragDrop_1(object sender, DragEventArgs e)
        {
            //处理 treeView1控件DragDrop事件
            TreeNode MyNode = (TreeNode)e.Data.GetData(typeof(TreeNode));
            TreeView MyTreeView = (TreeView)sender;
            //得到当前鼠标进入的节点
            TreeNode MyTargetNode = MyTreeView.GetNodeAt(treeView1.PointToClient(new Point(e.X, e.Y)));
            if (MyTargetNode != null)
            {
                TreeNode MyTargetParent = MyTargetNode.Parent;
                //删除拖放的节点
                MyNode.Remove();
                //添加到目标节点
                MyTargetNode.Nodes.Add(MyNode);
                MyTargetNode.BackColor = Color.White;
                MyTreeView.SelectedNode = MyTargetNode;
            }
        }

        private void treeView1_ItemDrag_1(object sender, ItemDragEventArgs e)
        {
            //处理 treeView1控件ItemDrag事件
            //设置拖放类型为移动
            DoDragDrop(e.Item, DragDropEffects.Move);
        }   
    }
}