隨即繪製驗證碼圖像

 

protected void Page_Load(object sender, EventArgs e)
 {
     Bitmap bmp = new Bitmap(80, 40);//定義一個畫布
     Graphics g = Graphics.FromImage(bmp);
     g.Clear(Color.White);
     g.DrawRectangle(Pens.Black, 0, 0, 79, 39);//繪製邊框
     //定義七種顏色
     Color[] colors = { Color.Black, Color.Red, Color.Blue, Color.DarkGreen, Color.Purple, Color.DarkGoldenrod, Color.Chocolate };
     //定義七種字體
     string[] fontNames = { "宋體", "楷體_GB2312", "隸書", "Arial", "Comic Sans MS", "Microsoft Sans Serif", "Times New Roman" };
     //隨機數
     Random rand = new Random();
     //隨機生成驗證字符
     char[] chs = new char[] { (char)(65 + rand.Next(26)), (char)(65 + rand.Next(26)), (char)(65 + rand.Next(26)) };
     Brush brush;//定義畫刷
     Font font;//定義字體
     int x, y;//座標
     for (int i = 0; i < 3; i++)
     {
         brush = new SolidBrush(colors[rand.Next(7)]);
         font = new Font(fontNames[rand.Next(7)], 18, FontStyle.Bold);
         x = i * 20 + 2;
         y = 5 + rand.Next(5);
         g.RotateTransform(rand.Next(-10, 9));
         //畫出字符
         g.DrawString(chs[i].ToString(), font, brush, x, y);
     }

     Pen[] pens = { Pens.Gray, Pens.LightGray };
     for (int i = 0; i < 200; i++)//繪製隨機躁點
     {
         x = rand.Next(bmp.Width - 1);
         y = rand.Next(bmp.Height - 1);
         g.DrawEllipse(pens[i % 2], x, y, 1, 1);
     }

     MemoryStream ms = new MemoryStream();
     bmp.Save(ms, ImageFormat.Jpeg);
     this.Response.Clear();
     this.Response.ContentType = "p_w_picpath/Jpeg";
     this.Response.BinaryWrite(ms.ToArray());//輸出圖像
     g.Dispose();
     bmp.Dispose();
 }