using System;

using System.Drawing;

using System.Web;

using System.Web.SessionState;

namespace Zhong.Web

{

    /// <summary>

    /// VerifyCode 的摘要说明

    /// </summary>

    public class VerifyCode : IHttpHandler,IRequiresSessionState

    {

        public void ProcessRequest(HttpContext context)

        {

            context.Response.ContentType = "image/gif";

            string code = GetCode();   //产生6位随机数

            context.Session["verifycode"] = code;   //保存到Session中

            System.Drawing.Bitmap image = new System.Drawing.Bitmap(, );

            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

                int i;

                for (i = ; i < ; 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 Font("Arial", , (FontStyle.Bold));

                System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(, , image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2F, true);

                g.DrawString(code, font, brush, , );

                //画图片的前景噪音点

                g.DrawRectangle(new Pen(Color.Silver), , , image.Width - , image.Height - );

                System.IO.MemoryStream ms = new System.IO.MemoryStream();

                image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);

                context.Response.ClearContent();

                context.Response.ContentType = "image/Gif";

                context.Response.BinaryWrite(ms.ToArray());

            }

            finally

            {

                g.Dispose();

                image.Dispose();

            }

        }

        /// <summary>

        /// 产生随机数

        /// </summary>

        /// <param name="length">随机数长度</param>

        /// <returns></returns>

        private string GetCode(int length)

        {

            string str = "0123456789abcdefghijklmnpqrstuvwxyzABCDEFGHIJKLMNPQRSTUVWXYZ";

            //char[] letters = str.ToCharArray();

            string code = "";

            Random random = new Random();

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

            {

                code += str.Substring(random.Next(str.Length), );

            }

            return code;

        }

        public bool IsReusable

        {

            get

            {

                return false;

            }

        }

    }

}