ASP.NET中绘制图片

using System.Drawing;
using System.IO;
using System.Drawing.Imaging;

private void CreateCheckCodeImage(string checkCode)
           {
               if (checkCode == null || checkCode.Trim() == String.Empty)
                   return;

               System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 22);
               Graphics g = Graphics.FromImage(image);

               try
               {
                   //生成随机生成器
                   Random random = new Random();

                   //清空图片背景色
                   g.Clear(Color.White);

                   //画图片的背景噪音线
                   for (int i = 0; i < 25; i++)
                   {
                       int x1 = random.Next(image.Width);
                       int x2 = random.Next(image.Width);
                       int y1 = random.Next(image.Height);
                       int y2 = random.Next(image.Height);

                       g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
                   }

                   Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));
                   System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);
                   g.DrawString(checkCode, font, brush, 2, 2);

                   //画图片的前景噪音点
                   for (int i = 0; i < 100; i++)
                   {
                       int x = random.Next(image.Width);
                       int y = random.Next(image.Height);

                       image.SetPixel(x, y, Color.FromArgb(random.Next()));
                   }

                   //画图片的边框线
                   g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);

                   System.IO.MemoryStream ms = new System.IO.MemoryStream();
                   image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
                   HttpContext.Current.Response.ClearContent();
                   HttpContext.Current.Response.ContentType = "image/Gif";
                   HttpContext.Current.Response.BinaryWrite(ms.ToArray());
               }
               finally
               {
                   g.Dispose();
                   image.Dispose();
               }
 }