private void pictureBox1_Click(object sender, EventArgs e)
        {
            Random r = new Random();
            string str = null;
            for (int i = 0; i < 8; i++)
            {
                int rNumber = r.Next(0, 10);
                str += rNumber;
            }
            //  MessageBox.Show(str);
            //创建GDI对象
            Bitmap bmp = new Bitmap(200, 40);
            Graphics g = Graphics.FromImage(bmp);

            for (int i = 0; i < 8; i++)
            {
                Point p = new Point(i * 20, 0);
                string[] fonts = { "微软雅黑", "宋体", "黑体", "隶书", "仿宋" };
                Color[] colors = { Color.Yellow, Color.Blue, Color.Black, Color.Red, Color.Green };
                g.DrawString(str[i].ToString(), new Font(fonts[r.Next(0, 5)], 20, FontStyle.Bold), new SolidBrush(colors[r.Next(0, 5)]), p);
            }

            for (int i = 0; i < 20; i++)
            {
                Point p1=new Point(r.Next(0,bmp.Width),r.Next(0,bmp.Height));
                Point p2=new Point(r.Next(0,bmp.Width),r.Next(0,bmp.Height));
                g.DrawLine(new Pen(Brushes.Green), p1, p2);
            }

            for (int i = 0; i < 500; i++)
            {
                Point p=new Point(r.Next(0,bmp.Width),r.Next(0,bmp.Height));
                bmp.SetPixel(p.X, p.Y, Color.Black);//设置像素
            }


            //将图片镶嵌到PictureBox中
            pictureBox1.Image = bmp;
        }