using System;
using System.Collections.Generic;
using System.Web;
using System.Web.Security;
using System.Web.SessionState;
using System.Drawing;
using System.Drawing.Imaging;


namespace Mtxfw.VipSite
{
    /// <summary>
    /// 验证码 by Telesa 2011.04.07
    /// </summary>
    public class CheckCode : IHttpHandler, IRequiresSessionState
    {
        public void ProcessRequest(HttpContext context)
        {
            string strNum = RandNum(4);
            context.Session["GLRandNum"] = strNum;
            ValidateCode(strNum, 60, 25, "Arial", 12, "#FFFFFF");
        }

        /// <summary>
        /// 生成指定位数的随机数
        /// </summary>
        /// <param name="VcodeNum">参数是随机数的位数</param>
        /// <returns>返回一个随机数字符串</returns>
        public string RandNum(int VcodeNum)
        {
            Random random = new Random();
            if (VcodeNum == 6)
            {
                return (random.Next(100000, 999999).ToString());
            }
            else
            {
                return (random.Next(1000, 9999).ToString());
            }
        }

        /// <summary>
        /// 生成图片并写入字符
        /// </summary>
        /// <param name="VNum">目标字符</param>
        /// <param name="w">宽</param>
        /// <param name="h">高</param>
        /// <param name="font">字体文件</param>
        /// <param name="fontSize">字体大小</param>
        /// <param name="bgColor">图片背景颜色</param>
        private void ValidateCode(string VNum, int w, int h, string font, int fontSize, string bgColor)
        {
            //生成图像的实例
            Bitmap Img = new Bitmap(w, h);
            //从Img对象生成新的Graphics对象
            Graphics g = Graphics.FromImage(Img);
            //背景颜色
            g.Clear(ColorTranslator.FromHtml(bgColor));
            //生成Font类的实例
            Font f = new Font(font, fontSize, FontStyle.Italic|FontStyle.Bold);
            
            //生成笔刷类的实例
            SolidBrush s = new SolidBrush(Color.Red);
            //将VNum写入图片中
            g.DrawString(VNum, f, s, 3, 3);
            //将此图像以Jpeg图像文件的格式保存到流中
            Img.Save(System.Web.HttpContext.Current.Response.OutputStream, ImageFormat.Jpeg);
            System.Web.HttpContext.Current.Response.ContentType = "image/Jpeg";

            g.Dispose();
            Img.Dispose();
            System.Web.HttpContext.Current.Response.End();
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }
}