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();      //設置提示工具的相關屬性值      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>    /// 顯示用戶信息    /// </summary>    /// <param name="sender"></param>    /// <param name="e"></param>    private void MainForm_Load(object sender, EventArgs e)    {      string sql = "select 用戶ID=userID,用戶名=name,用戶登錄名=username,用戶密碼=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);//鼠標移出單元格后隱藏提示工具    }    private void dgvUserInfo_CellMouseEnter(object sender, DataGridViewCellEventArgs e)    {      //判斷選擇單元格的有效性      if (e.RowIndex < 0 || e.ColumnIndex < 0)      {        return;      }      this.toolTip.Hide(this.dgvUserInfo);      this.cellColumnIndex = e.ColumnIndex;//獲取列索引      this.cellRowIndex = e.RowIndex;//獲取行索引      if (this.cellColumnIndex >= 0 && this.cellRowIndex >= 0)      {        Point mousePos = PointToClient(MousePosition);//獲取鼠標當前的位置        //獲取鼠標移入的單元格中的值        string tip = this.dgvUserInfo[this.cellColumnIndex, this.cellRowIndex].Value.ToString();        this.toolTip.Show(tip, this.dgvUserInfo, mousePos);//在指定位置顯示提示工具      }    }    //繪制提示工具    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);    }  }}