/// <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 = ; i < ; i++)

             {

                 str += r.Next(, );

             }

             Bitmap bitmap = new Bitmap(, );

             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 = ; i < str.Length; i++)

             {

                 Point p = new Point(i * , );

                 g.DrawString(str[i].ToString(), new Font(fonts[r.Next(, )], , FontStyle.Bold), new SolidBrush(colors[r.Next(, )]), p);

             }

             //循环在图片范围内绘制出50条线

             for (int i = ; i < ; i++)

             {

                 //保证线的起始点都在图片范围内

                 Point p1 = new Point(r.Next(, bitmap.Width), r.Next(, bitmap.Height));

                 Point p2 = new Point(r.Next(, bitmap.Width), r.Next(, bitmap.Height));

                 g.DrawLine(new Pen(Brushes.Green), p1, p2);

             }

             //添加一些像素点

             for (int i = ; i < ; i++)

             {

                 Point p1 = new Point(r.Next(, bitmap.Width), r.Next(, bitmap.Height));

                 bitmap.SetPixel(p1.X, p1.Y, Color.Green);

             }

             //在winForm中用PictureBox中显示出来

             pictureBox1.Image = bitmap;

         }