通过WebService(C＃)返回CAPTCHA映像

Question

i使用本文进行create catcha映像，然后我将其代码放在返回image'captcha到客户端的Web服务中（app.js），但我有很多错误。

我的网络服务：

public class Captcha : System.Web.Services.WebService
{
[WebMethod(EnableSession = true)]
        public Bitmap CaptchaImage()
        {
            bool noisy = true;
            var rand = new Random((int)DateTime.Now.Ticks);
            //generate new question
            int a = rand.Next(10, 99);
            int b = rand.Next(0, 9);
            var captcha = string.Format("{0} + {1} = ?", a, b);
            //store answer
            Session["Captcha-1"] = a + b;
            //image stream
            FileContentResult img = null; //get error for FileContentResult
            using (var mem = new MemoryStream())
            using (var bmp = new Bitmap(130, 30))
            using (var gfx = Graphics.FromImage((System.Drawing.Image)bmp))
            {
                gfx.TextRenderingHint = TextRenderingHint.ClearTypeGridFit;
                gfx.SmoothingMode = SmoothingMode.AntiAlias;
                gfx.FillRectangle(Brushes.White, new Rectangle(0, 0, bmp.Width, bmp.Height));
                //add noise
                if (noisy)
                {
                    int i, r, x, y;
                    var pen = new Pen(Color.Yellow);
                    for (i = 1; i < 10; i++)
                    {
                        pen.Color = Color.FromArgb(
                        (rand.Next(0, 255)),
                        (rand.Next(0, 255)),
                        (rand.Next(0, 255)));
                        r = rand.Next(0, (130 / 3));
                        x = rand.Next(0, 130);
                        y = rand.Next(0, 30);
                        gfx.DrawEllipse(pen, x - r, y - r, r, r);
                    }
                }
                //add question
                gfx.DrawString(captcha, new Font("Tahoma", 15), Brushes.Gray, 2, 3);
                //render as Jpeg
                bmp.Save(mem, System.Drawing.Imaging.ImageFormat.Bmp);
                img = this.File(mem.GetBuffer(), "image/Jpeg"); //get error for .file
            }
                return img;
        }
}

有没有办法解决这些错误？！

Answer 1

i由此代码结束：

   //render as Jpeg
   bmp.Save(mem, ImageFormat.Jpeg);
   byte[] imageBytes = mem.ToArray();
   string base64String = Convert.ToBase64String(imageBytes);
   //img = this.File(mem.GetBuffer(), "image/Jpeg");
   return base64String;
}
//return img;