C# GDI在控件上绘图

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(, ); //鼠标第一点
public Point secondPoint = new Point(, ); //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);
} }
}