C#中Winform的Treeview节点"正在展开..."的效果

比较简单的做法，增加一个子节点提示．然后开线程请求真实的子节点，完毕后替换提示节点。　

代码如下

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

namespace WindowsApplication11
{
    public partial class Form1 : Form
    {

        //用于控制线程的方法
        public class ThreadStartInfo
        {
            public TreeNode node=null;

            //模拟载入数据
            public  void LoadNode()
            {
                System.Threading.Thread.Sleep(5000);
                string[] str = new string[] { "jinjazz", "csdn" ,"sina","google","yahoo","nba","fifa"};
                this.AddNode(node, str);
            }
            delegate void dAddNode(TreeNode node, string[] str);

            //添加节点
            void AddNode(TreeNode node, string[] str)
            {
                if (this.node.TreeView.FindForm().InvokeRequired)
                {
                    this.node.TreeView.FindForm().Invoke(new dAddNode(AddNode), new object[] { node, str });
                }
                else
                {
                    node.Nodes.Clear();
                    foreach (string strNode in str)
                    {
                        node.Nodes.Add(strNode);
                    }
                }

            }
        }

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            //添加根节点
            this.treeView1.Nodes.Add(new TreeNode("root"));
            this.treeView1.AfterSelect += new TreeViewEventHandler(treeView1_AfterSelect);
        }

        void treeView1_AfterSelect(object sender, TreeViewEventArgs e)
        {
            if (e.Node.Tag==null||e.Node.Tag.ToString() == "")
            {
                ThreadStartInfo s = new ThreadStartInfo();
                s.node = e.Node;
                //已经载入过的就不要载入了。
                s.node.Tag = 1;
                new System.Threading.Thread(new System.Threading.ThreadStart(s.LoadNode)).Start();
                e.Node.Nodes.Add("正在载入..");
            }
        }
    }
}