using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Web.UI;
using System.Drawing.Drawing2D;
using System.IO;
namespace Validate
{
 /// <summary>
 /// 生成验证码的类
 /// </summary>
 public class ValidateNumber
 {
  public ValidateNumber()
  {
  }
  /// <summary>
  /// 验证码的最大长度
  /// </summary>
  public int MaxLength
  {
get{return 10;}
  }
  /// <summary>
  /// 验证码的最小长度
  /// </summary>
  public int MinLength
  {
get{return 1;}
  }
  /// <summary>
  /// 生成验证码
  /// </summary>
  /// <param name="length">指定验证码的长度</param>
  /// <returns></returns>
  public string CreateValidateNumber(int length)
  {
int[] randMembers=new int[length];
int[] validateNums=new int[length];
string validateNumberStr="";
//生成起始序列值
int seekSeek=unchecked((int)DateTime.Now.Ticks);
Random seekRand=new Random(seekSeek);
int beginSeek=(int)seekRand.Next(0,Int32.MaxValue-length*10000);
int[] seeks=new int[length];
for(int i=0;i<length;i++)
{
 beginSeek+=10000;
 seeks[i]=beginSeek;
}
//生成随机数字
for(int i=0;i<length;i++)
{
 Random rand=new Random(seeks[i]);
 int pownum=1*(int)Math.Pow(10,length);
 randMembers[i]=rand.Next(pownum,Int32.MaxValue);
}
//抽取随机数字
for(int i=0;i<length;i++)
{
 string numStr=randMembers[i].ToString();
 int numLength=numStr.Length;
 Random rand=new Random();
 int numPosition=rand.Next(0,numLength-1);
 validateNums[i]=Int32.Parse(numStr.Substring(numPosition,1));
}
//生成验证码
for(int i=0;i<length;i++)
{
 validateNumberStr+=validateNums[i].ToString();
}
return validateNumberStr;
  }
  /// <summary>
  /// 创建验证码的图片
  /// </summary>
  /// <param name="containsPage">要输出到的page对象</param>
  /// <param name="validateNum">验证码</param>
  public void CreateValidateGraphic(Page containsPage,string validateNum)
  {
Bitmap image=new Bitmap((int)Math.Ceiling(validateNum.Length*12.5),22);
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);
 //画图片的干扰线
 for(int i=0;i<25;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",12,(FontStyle.Bold|FontStyle.Italic));
 LinearGradientBrush brush=new LinearGradientBrush(new Rectangle(0,0,image.Width,image.Height),
  Color.Blue,Color.DarkRed,1.2f,true);
 g.DrawString(validateNum,font,brush,3,2);
 //画图片的前景干扰点
 for(int i=0;i<100;i++)
 {
  int x=random.Next(image.Width);
  int y=random.Next(image.Height);
  image.SetPixel(x,y,Color.FromArgb(random.Next()));
 }
 //画图片的边框线
 g.DrawRectangle(new Pen(Color.Silver),0,0,image.Width-1,image.Height-1);
 //保存图片数据
 MemoryStream stream=new MemoryStream();
 image.Save(stream,ImageFormat.Jpeg);
 //输出图片
 containsPage.Response.Clear();
 containsPage.Response.ContentType="image/jpeg";
 containsPage.Response.BinaryWrite(stream.ToArray());
}
finally
{
 g.Dispose();
 image.Dispose();
}
  }
  /// <summary>
  /// 得到验证码图片的长度
  /// </summary>
  /// <param name="validateNumLength">验证码的长度</param>
  /// <returns></returns>
  public static int GetImageWidth(int validateNumLength)
  {
return (int)(validateNumLength*12.5);
  }
  /// <summary>
  /// 得到验证码的高度
  /// </summary>
  /// <returns></returns>
  public static double GetImageHeight()
  {
return 22.5;
  }
 }
}