1、新建一个窗体应用程序，在上面拖一个pictureBox对象，为其添加单击事件

2、创建GDI对象、产生随机数画入图片中、画线条、最后将图片到pictureBox中，代码如下：

1  private void pictureBox1_Click(object sender, EventArgs e) 2         { 3             //创建GDI对象 4             Bitmap bmp = new Bitmap(150,40); 5             Graphics g = Graphics.FromImage(bmp); 6  7            //产生随机数并画入图片中 8             Random r = new Random(); 9             string str = "";10             for (int i = 0; i < 5;i++ )11             {12                 str += r.Next(0,10);13             }14             for (int i = 0; i < 5; i++) 15             {16                 Point p = new Point(i*20,0);17                 string[] fonts = { "微软雅黑", "宋体", "黑体", "隶书", "仿宋" };18                 Color[] colors = { Color.Yellow,Color.Blue,Color.Black,Color.Red,Color.Pink};19                 g.DrawString(str[i].ToString(),new Font(fonts[r.Next(0,5)],20,FontStyle.Bold),new SolidBrush(colors[r.Next(0,5)]),p);20             21             }22 23             //画线24             for (int i = 0; i < 20; i++)25             {26                 Point p1 = new Point(r.Next(0,bmp.Width),r.Next(0,bmp.Height));27                 Point p2 = new Point(r.Next(0,bmp.Width),r.Next(0,bmp.Height));28                 g.DrawLine(new Pen(Brushes.Green),p1,p2);29             }30 31             //将图片镶嵌到pictureBox中32             pictureBox1.Image = bmp;33 34         }