学习笔记：利用GDI+生成简单的验证码图片

学习笔记：利用GDI+生成简单的验证码图片

/// <summary>
        /// 单击图片时切换图片
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void pictureBox1_Click(object sender, EventArgs e)
        {
            Random r = new Random();
            string str = string.Empty;
            //生成5位随机数如 90531
            for (int i = 0; i < 5; i++)
            {
                str += r.Next(0, 10);
            }
            Bitmap bitmap = new Bitmap(150, 40);
            Graphics g = Graphics.FromImage(bitmap);
            //预定义几种字体样式和颜色
            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.Orange };
            //因为每一数字的字体和颜色可能不同，
            //因此循环将生成的随机数每一数字绘制到图片
            for (int i = 0; i < str.Length; i++)
            {
                Point p = new Point(i * 30, 0);
                g.DrawString(str[i].ToString(), new Font(fonts[r.Next(0, 5)], 20, FontStyle.Bold), new SolidBrush(colors[r.Next(0, 5)]), p);
            }
            //循环在图片范围内绘制出50条线
            for (int i = 0; i < 50; i++)
            {
                //保证线的起始点都在图片范围内
                Point p1 = new Point(r.Next(0, bitmap.Width), r.Next(0, bitmap.Height));
                Point p2 = new Point(r.Next(0, bitmap.Width), r.Next(0, bitmap.Height));
                g.DrawLine(new Pen(Brushes.Green), p1, p2);
            }
            //添加一些像素点
            for (int i = 0; i < 300; i++)
            {
                Point p1 = new Point(r.Next(0, bitmap.Width), r.Next(0, bitmap.Height));
                bitmap.SetPixel(p1.X, p1.Y, Color.Green);
            }
            //在winForm中用PictureBox中显示出来
            pictureBox1.Image = bitmap;
        }

 最终效果如下