C# GDI在控件上绘图的方法

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.IO;
using System.Configuration;

namespace WFApp2
{
  public partial class data : Form
  {
    public data()
    {
      InitializeComponent();
      //窗体
      g = this.CreateGraphics();
      //chart控件
      g2 = this.chart1.CreateGraphics();
    }
   
    public Point firstPoint = new Point(0, 0); //鼠标第一点 
    public Point secondPoint = new Point(0, 0); //鼠标第二点 
    public bool begin = false;  //是否开始画矩形 
    /// <summary>
    /// 在from上画矩形
    /// </summary>
    Graphics g;

    /// <summary>
    /// 在chart1控件上画矩形
    /// </summary>
    Graphics g2;

    /// <summary>
    /// 在窗体上按下鼠标事件
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    private void data_MouseDown(object sender, MouseEventArgs e)
    {
      begin = true;
      firstPoint = new Point(e.X, e.Y);
    }

    /// <summary>
    /// 在窗体上鼠标移动开始绘图
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    private void data_MouseMove(object sender, MouseEventArgs e)
    {
      if (begin)
      {
        //清除窗体绘图面,相当于刷新了一次窗体界面然后重新绘制
        g.Clear(this.BackColor);
        //获取新的右下角坐标 
        secondPoint = new Point(e.X, e.Y);
        //获取两个数中的大者或小者
        int minX = Math.Min(firstPoint.X, secondPoint.X);
        int minY = Math.Min(firstPoint.Y, secondPoint.Y);
        int maxX = Math.Max(firstPoint.X, secondPoint.X);
        int maxY = Math.Max(firstPoint.Y, secondPoint.Y);

        //画框 
        g.DrawRectangle(new Pen(Color.Red), minX, minY, maxX - minX, maxY - minY);
        //ControlPaint.DrawReversibleFrame(new Rectangle(minX, minY, maxX - minX, maxY - minY),this.BackColor,FrameStyle.Dashed);

      }
    }

    /// <summary>
    /// 鼠标松开停止绘图
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    private void data_MouseUp(object sender, MouseEventArgs e)
    {
      begin = false;
    }

    /// <summary>
    /// 在chart控件上移动鼠标绘图
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    private void chart1_MouseMove(object sender, MouseEventArgs e)
    {
      if (begin)
      {
        //重新在chart上面绘图，此处不能用clear方法，clear会清除整个绘图界面chart控件会被清除
        this.Refresh();
        //获取新的右下角坐标 
        secondPoint = new Point(e.X, e.Y);
        int minX = Math.Min(firstPoint.X, secondPoint.X);
        int minY = Math.Min(firstPoint.Y, secondPoint.Y);
        int maxX = Math.Max(firstPoint.X, secondPoint.X);
        int maxY = Math.Max(firstPoint.Y, secondPoint.Y);

        //画矩形
        g2.DrawRectangle(new Pen(Color.Red), minX, minY, maxX - minX, maxY - minY);

      }
    }

    /// <summary>
    /// 鼠标松开停止绘图
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    private void chart1_MouseUp(object sender, MouseEventArgs e)
    {
      begin = false;
    }

    /// <summary>
    /// 在chart控件上按下鼠标
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    private void chart1_MouseDown(object sender, MouseEventArgs e)
    {
      begin = true;
      firstPoint = new Point(e.X, e.Y);
    }
  }
}