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();
       }
 }