C#橡皮筋画线代码 学习必备

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; namespace WindowsFormsApplication97 { public partial class Form1 : Form { public Form1() { InitializeComponent(); } //定义画线的两个点p1起始点p2终点 private Point p1,p2; //定义存储绘过的所有对象(窗体刷新时用来重绘) private List<drawtype> ls = new List<drawtype>(); public Bitmap image = null; //窗体载入时新建一个绘图对象 private void Form1_Load(object sender, EventArgs e) { this.pictureBox1.Controls.Clear(); image = new Bitmap(this.pictureBox1.Width, this.pictureBox1.Height); Graphics.FromImage(image).Clear(Color.White);//消除底图的黑色 this.pictureBox1.Image = (Bitmap)image.Clone();//这句话是关键 } //点击保存图片 private void button1_Click(object sender, EventArgs e) { SaveFileDialog sf = new SaveFileDialog(); sf.Filter="(*.bmp)|*.bmp|(*.jpg)|*.jpg"; sf.FilterIndex = 2; sf.RestoreDirectory = true; if (sf.ShowDialog()==DialogResult.OK) { pictureBox1.Image.Save(sf.FileName); } } //当鼠标点击窗体时记录坐标点(用来记录直线的第一个坐标) private void pictureBox1_MouseDown(object sender, MouseEventArgs e) { //开始记录坐标 p1 = e.Location; } //鼠标在窗体中按下时的绘图过程 private void pictureBox1_MouseMove(object sender, MouseEventArgs e) { Graphics g = pictureBox1.CreateGraphics(); //如果鼠标左键一直接下 if (e.Button == MouseButtons.Left) { //开始画白线(与背景色一样的线,用来擦除鼠标移动时产生的线) g.DrawLine(new Pen(Color.White, 2), p1, p2); //获得鼠标在窗体中按下并移动时的坐标点 p2 = e.Location; //在窗体中画出的线 g.DrawLine(new Pen(Color.Blue, 2), p1, p2); //使用枚举将所有画过的线重绘(为了防止新画的线的白色会将原有线更改) chonghui(); } } private void chonghui() { Graphics g = pictureBox1.CreateGraphics(); foreach (drawtype t in ls) { //画出原有的每一条线 g.DrawLine(new Pen(Color.Blue, 2), t.p1, t.p2); } } //鼠标点击弹起时,记录刚刚画线的位置 private void pictureBox1_MouseUp(object sender, MouseEventArgs e) { //记录画线的位置,放到泛型集合中 ls.Add(new drawtype(p1, new Point(e.X,e.Y))); } private void pictureBox1_Paint(object sender, PaintEventArgs e) { Graphics g = pictureBox1.CreateGraphics(); chonghui(); } private void pictureBox1_Click(object sender, EventArgs e) { } } //定义存储画线动作的类 class drawtype { //定义两个点 public Point p1, p2; //定义构造方法(两个点为参数) public drawtype(Point pp, Point pp2) { p1 = pp; p2 = pp2; } } }