C#中datagridview使用tooltip控件显示单元格内容的方法

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;
namespace Exam2
{
  public partial class MainForm : Form
  {
    private int cellColumnIndex = -1;//列索引
    private int cellRowIndex = -1;//行索引
    public MainForm()
    {
      InitializeComponent();
      //设置提示工具的相关属性值
      this.dgvUserInfo.ShowCellToolTips = false;
      this.toolTip.AutomaticDelay = 0;
      this.toolTip.OwnerDraw = true;
      this.toolTip.ShowAlways = true;
      this.toolTip.ToolTipTitle = " ";
      this.toolTip.UseAnimation = true;
      this.toolTip.UseFading = true;
    }
    /// <summary>
    /// 显示用户信息
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    private void MainForm_Load(object sender, EventArgs e)
    {
      string sql = "select 用户ID=userID,用户名=name,用户登录名=username,用户密码=userPassword from userInfo";
      SqlConnection conn = DBHelper.GetConnection();
      SqlDataAdapter adapter = new SqlDataAdapter(sql,conn);
      DataSet ds = new DataSet();
      adapter.Fill(ds);
      this.dgvUserInfo.DataSource = ds.Tables[0];
    }
    private void dgvUserInfo_CellMouseLeave(object sender, DataGridViewCellEventArgs e)
    {
      this.toolTip.Hide(this.dgvUserInfo);//鼠标移出单元格后隐藏提示工具
    }
    private void dgvUserInfo_CellMouseEnter(object sender, DataGridViewCellEventArgs e)
    {
      //判断选择单元格的有效性
      if (e.RowIndex < 0 || e.ColumnIndex < 0)
      {
        return;
      }
      this.toolTip.Hide(this.dgvUserInfo);
      this.cellColumnIndex = e.ColumnIndex;//获取列索引
      this.cellRowIndex = e.RowIndex;//获取行索引
      if (this.cellColumnIndex >= 0 && this.cellRowIndex >= 0)
      {
        Point mousePos = PointToClient(MousePosition);//获取鼠标当前的位置
        //获取鼠标移入的单元格中的值
        string tip = this.dgvUserInfo[this.cellColumnIndex, this.cellRowIndex].Value.ToString();
        this.toolTip.Show(tip, this.dgvUserInfo, mousePos);//在指定位置显示提示工具
      }
    }
    //绘制提示工具
    private void toolTip_Draw(object sender, DrawToolTipEventArgs e)
    {
      e.Graphics.FillRectangle(Brushes.AliceBlue, e.Bounds);
      e.Graphics.DrawRectangle(Pens.Chocolate, new Rectangle(0, 0, e.Bounds.Width - 1, e.Bounds.Height - 1));
      e.Graphics.DrawString(this.toolTip.ToolTipTitle + e.ToolTipText, e.Font, Brushes.Red, e.Bounds);
    }
  }
}