image.aspx.cs

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using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;

namespace ValidationCode
{

    public partial class Image : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            Random rd = new Random(); //创建随机数对象       

            int Results = 0;
            int Num1 = rd.Next(10); ;
            int Num2 = rd.Next(10); ;
            string Expressions = "";

            int F=(rd.Next(4)+1);
            switch (F)
            {
                case 1:
                    Results = Num1 + Num2;
                    Expressions = Num1 + "＋ " + Num2 + "＝ " + Results;
                    break;
                case 2:
                    Results = Num1 - Num2;
                    Expressions = Num1 + "－ " + Num2 + "＝ " + Results;
                    break;
                case 3:
                    Results = Num1 * Num2;
                    Expressions = Num1 + "×" + Num2 + "＝ " + Results;
                    break;
                case 4:
                    if (Num2 > 0)
                    {
                        Results = Convert.ToInt16(Num1 / Num2);
                        Expressions = Num1 + "整除 " + Num2 + "＝ " + Results;
                    }
                    else
                    {
                        Results = Num1;
                        Expressions = Num1 + "整除 1＝ " + Results;
                    }
                    break;
            }

            //验证码值存放到Session中用来比较
            Session["Code"] = Results.ToString();

            //以下通过随机找一个现有图象产生一个画布Bitmap
            //随机找个背景
            string bgFilePath = Server.MapPath(".\\images\\bg" + new Random().Next(5) + ".jpg");
            //string bgFilePath = Server.MapPath(".\\images\\bg10.jpg");


            System.Drawing.Image imgObj = System.Drawing.Image.FromFile(bgFilePath);
            //建立位图对象
            Bitmap newBitmap = new Bitmap(imgObj, 290, 80);

            //根据上面创建的位图对象创建绘图面
            Graphics g = Graphics.FromImage(newBitmap);
            //设置画笔颜色
            SolidBrush brush = new SolidBrush(Color.Blue);

            //定义一个含10种字体的数组
            String[] fontFamily ={ "Arial", "Verdana", "Comic Sans MS", "Impact", "Haettenschweiler", "Lucida Sans Unicode", "Garamond", "Courier New", "Book Antiqua", "Arial Narrow" };


            //通过循环,绘制每个字符,
            for (int a = 0; a < Expressions.Length; a++)
            {
                //字体随机,字号大小30,加粗 
                Font textFont = new Font(fontFamily[rd.Next(9)],20, FontStyle.Bold);
                //每次循环绘制一个字符,设置字体格式,画笔颜色,字符相对画布的X坐标,字符相对画布的Y坐标
                g.DrawString(Expressions.Substring(a, 1), textFont, brush, 20 + a * 22, 25);
            }

            //保存画的图片到输出流中
            newBitmap.Save(Response.OutputStream, ImageFormat.Gif);

        }
    }
}