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;

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

{

    private int codelen = ; //验证码长度

    private int finenes = ; //图片清晰度

    private int imageHeight = ;//图片高度

    private int imgWidth = ; //图片宽度

    private string fontfamily = "微软雅黑"; //字体样式

    private int fontsize = ; //字体大小

    private int x = ; //x坐标

    private int y = ; //y坐标

    protected void Page_Load(object sender, EventArgs e)

    {

        //验证码

        string validateCode = CreateCodeVerfiy();//生成验证码

        Bitmap bitmap = new Bitmap(imgWidth, imageHeight);//生成Bitmap图像

        ImageBig(bitmap); //图像背景

        DrewValidateCode(bitmap, validateCode);//绘制验证码图像

        bitmap.Save(Response.OutputStream, ImageFormat.Jpeg);//保存图像，等待输出 

    }

    //验证码数字的生成

    protected string CreateCodeVerfiy()

    {

        string code = "";

        Random rd = new Random();

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

        {

            int n = rd.Next(); //随机生成4个数字

            code += n.ToString();

        }

        Session["verify"] = code;

        return code;

    }

    //干扰点生成

    protected void ImageBig(Bitmap bimtmp)

    {

        Random rd = new Random();

        for (int i = ; i < bimtmp.Width; i++)

        {

            for (int j = ; j < bimtmp.Height; j++)

            {

                if (rd.Next() <= this.finenes)

                {

                    bimtmp.SetPixel(i, j, Color.LightBlue);

                }

            }

        }

    }

    private void DrewValidateCode(Bitmap bitmap, string validateCode)//绘制验证码图像

    {

        Graphics g = Graphics.FromImage(bitmap);//获取绘制器对象

        Font font = new Font(fontfamily, fontsize, FontStyle.Bold);//设置绘制字体

        g.DrawString(validateCode, font, Brushes.Black, x, y);//绘制验证码图像

    }

}