C#,GDI绘制验证码!

        /// <summary>
        /// 单击更换验证码
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void pictureBox1_Click(object sender, EventArgs e)
        {
            //1,生产随机对象Random,生成随机数和验证码
            Random r = new Random();
            //随机产生验证码字符
            string str = null;
            for (int i = 0; i < 5; i++)
            {
                str += r.Next(0, 10).ToString();
            }
            //MessageBox.Show(str);

            //创建GDI对象
            Bitmap bmp = new Bitmap(120, 40); //创建位图
            Graphics g = Graphics.FromImage(bmp);   //创建GDI
            //颜色
            Color[] cs = { Color.Red, Color.Blue, Color.Black, Color.BlueViolet, Color.Green, Color.DarkRed };

            //绘制验证码文本字符串
            for (int i = 0; i < 5; i++)
            {
                //绘制字体
                string[] typeface = { "微软雅黑", "黑体", "宋体", "仿宋", "隶书", "楷书" };
                Font font = new Font(typeface[r.Next(0, 6)], 20, FontStyle.Bold);
                //颜色
                //Color[] cs = { Color.Red, Color.Blue,Color.LightGray,Color.Gray,Color.Green,Color.GhostWhite };
                g.DrawString(str[i].ToString(), font, new SolidBrush(cs[r.Next(0, 6)]), new Point(i * 20, 0));
            }

            //绘制干扰线 ,画直线
            for (int i = 0; i < 30; i++)
            {

                Pen pen = new Pen(cs[r.Next(0, 3)], 1);//画笔
                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(pen, p1, p2);

            }

            //设置像素点颜色
            for (int i = 0; i < 500; i++)
            {
                bmp.SetPixel(r.Next(0, bmp.Width), r.Next(0, bmp.Height),Color.Black);
            }

            //将绘制图片嵌入pictureBox中
            pictureBox1.Image = bmp;


        }