using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Drawing;

using System.Drawing.Imaging;

namespace AnalyzerExtAuth.Common

{

    public partial class ValidateCodeImg : System.Web.UI.Page

    {

        protected void Page_Load(object sender, EventArgs e)

        {

            //验证码中可能会出现的字符集合

            String checkCodeString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";

            //验证码字符集合的长度

            int length = checkCodeString.Length;

            //设置绘制验证码的字体,并设置为粗体并倾斜

            Font font = new Font("宋体", , (FontStyle.Bold | FontStyle.Italic));

            //绘制验证码的笔刷

            Brush brush = null;

            //绘制验证码文字的颜色

            Color brushColor = new Color();

            //验证码的字符串

            String checkCode = String.Empty;

            //当前要绘制的验证字符

            String code = String.Empty;

            //要生成的验证码图片对象

            Bitmap image = new Bitmap(, );

            //绘图画板

            Graphics graphics = Graphics.FromImage(image);

            //填充背景为白色

            graphics.Clear(Color.White);

            //创建随机数对象

            Random random = new Random();

            int x1, x2, y1, y2;

            Pen pen = new Pen(Color.Silver);

            //画背景噪音线

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

            {

                x1 = random.Next(image.Width);

                y1 = random.Next(image.Height);

                x2 = random.Next(image.Width);

                y2 = random.Next(image.Height);

                graphics.DrawLine(pen, x1, y1, x2, y2);

            }

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

            {

                //为了保证取的字符索引不超过0-35之间

                //取任何数的余数都肯定小于自身

                //采用当前时间的毫秒 % 验证码字符的总长度=当前验证字符

                int current = random.Next(DateTime.Now.Millisecond) % length;

                //截取验证字符

                code = checkCodeString.Substring(current, );

                //拼接到验证码的字符串

                checkCode += code;

                //随机生成验证码字符的颜色

                brushColor = Color.FromArgb(random.Next(), random.Next(), random.Next());

                //笔刷的颜色

                brush = new SolidBrush(brushColor);

                //绘制刚刚得到的字符串

                graphics.DrawString(code, font, brush, i *  + , );

            }

            Response.Clear();

            Response.ContentType = "image/pjpeg";

            //在Session中保存验证码字符串,以便与用户输入进行比较

            Session["CheckCode"] = checkCode;

            image.Save(Response.OutputStream, ImageFormat.Jpeg);

            image.Dispose();

            Response.End();

        }

    }

}