C# GIF验证码类

 namespace Kissogram.Common.Security
{
     using System;
     using System.IO;
     using System.Web;
     using System.Drawing;

     //GIF验证码类
     public class Validate
     {
         //设置最少4位验证码
         private byte TrueValidateCodeCount = 4;
         public byte ValidateCodeCount
         {
             get
             {
                 return TrueValidateCodeCount;
             }
             set
             {
                 //验证码至少为3位
                 if (value > 4)
                     TrueValidateCodeCount = value;
             }
         }
         protected string ValidateCode = "";
         //是否消除锯齿
         public bool FontTextRenderingHint = false;
         //验证码字体
         public string ValidateCodeFont = "Arial";
         //验证码型号(像素)
         public float ValidateCodeSize = 13;
         public int ImageHeight = 23;
         //定义验证码中所有的字符
         public string AllChar = "1,2,3,4,5,6,7,8,9,0,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,W,X,Y,Z";

         //获得随机四位数
         private void CreateValidate()
         {
             ValidateCode = "";
             //将验证码中所有的字符保存在一个字符串数组中
             string[] CharArray = AllChar.Split(',');
             int Temp = -1;
             //生成一个随机对象
             Random RandCode = new Random();
             //根据验证码的位数循环
             for (int i = 0; i < ValidateCodeCount; i++)
             {
                 //主要是防止生成相同的验证码
                 if (Temp != -1)
                 {
                     //加入时间的刻度
                     RandCode = new Random(i * Temp * ((int)DateTime.Now.Ticks));
                 }
                 int t = RandCode.Next(35);
                 if (Temp == t)
                 {
                     //相等的话重新生成
                     CreateValidate();
                 }
                 Temp = t;
                 ValidateCode += CharArray[Temp];
             }
             //错误检测,去除超过指定位数的验证码
             if (ValidateCode.Length > TrueValidateCodeCount)
                 ValidateCode = ValidateCode.Remove(TrueValidateCodeCount);
         }
         //生成一帧的BMP图象
         private void CreateImageBmp(out Bitmap ImageFrame)
         {
             //获得验证码字符
             char[] CodeCharArray = ValidateCode.ToCharArray(0, ValidateCodeCount);
             //图像的宽度-与验证码的长度成一定比例
             int ImageWidth = (int)(TrueValidateCodeCount * ValidateCodeSize * 1.3 + 4);
             //创建一个长20，宽iwidth的图像对象
             ImageFrame = new Bitmap(ImageWidth, ImageHeight);
             //创建一个新绘图对象
             Graphics ImageGraphics = Graphics.FromImage(ImageFrame);
             //清除背景色，并填充背景色
             //Note:Color.Transparent为透明
             ImageGraphics.Clear(Color.White);
             //绘图用的字体和字号
             Font CodeFont = new Font(ValidateCodeFont, ValidateCodeSize, FontStyle.Bold);
             //绘图用的刷子大小
             Brush ImageBrush = new SolidBrush(Color.Red);
             //字体高度计算
             int FontHeight = (int)Math.Max(ImageHeight - ValidateCodeSize - 3, 2);
             //创建随机对象
             Random rand = new Random();
             //开始随机安排字符的位置，并画到图像里
             for (int i = 0; i < TrueValidateCodeCount; i++)
             {
                 //生成随机点，决定字符串的开始输出范围
                 int[] FontCoordinate = new int[2];
                 FontCoordinate[0] = (int)(i * ValidateCodeSize + rand.Next(1)) + 3;
                 FontCoordinate[1] = rand.Next(FontHeight);
                 Point FontDrawPoint = new Point(FontCoordinate[0], FontCoordinate[1]);
                 //消除锯齿操作
                 if (FontTextRenderingHint)
                     ImageGraphics.TextRenderingHint = System.Drawing.Text.TextRenderingHint.SingleBitPerPixel;
                 else
                     ImageGraphics.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAlias;
                 //格式化刷子属性-用指定的刷子、颜色等在指定的范围内画图
                 ImageGraphics.DrawString(CodeCharArray[i].ToString(), CodeFont, ImageBrush, FontDrawPoint);
             }
             ImageGraphics.Dispose();
         }
         //处理生成的BMP
         private void DisposeImageBmp(ref Bitmap ImageFrame)
         {
             //创建绘图对象
             Graphics ImageGraphics = Graphics.FromImage(ImageFrame);
             //创建铅笔对象
             Pen ImagePen = new Pen(Color.Red, 1);
             //创建随机对象
             Random rand = new Random();
             //创建随机点
             Point[] RandPoint = new Point[2];
             //随机画线
             for (int i = 0; i < 15; i++)
             {
                 RandPoint[0] = new Point(rand.Next(ImageFrame.Width), rand.Next(ImageFrame.Height));
                 RandPoint[1] = new Point(rand.Next(ImageFrame.Width), rand.Next(ImageFrame.Height));
                 ImageGraphics.DrawLine(ImagePen, RandPoint[0], RandPoint[1]);
             }
             ImageGraphics.Dispose();
         }
         //创建GIF动画
         private void CreateImageGif()
         {
             Bitmap ImageFrame;
             Kissogram.Drawing.Gif.AnimatedGifEncoder GifPic = new Kissogram.Drawing.Gif.AnimatedGifEncoder();
             MemoryStream BmpMemory = new MemoryStream();
             GifPic.Start();
             //确保视觉残留
             GifPic.SetDelay(5);
             //-1:no repeat,0:always repeat
             GifPic.SetRepeat(0);
             for (int i = 0; i < 20; i++)
             {
                 //创建一帧的图像
                 CreateImageBmp(out ImageFrame);
                 //生成随机线条
                 DisposeImageBmp(ref ImageFrame);
                 //输出绘图,将图像保存到指定的流
                 ImageFrame.Save(BmpMemory, System.Drawing.Imaging.ImageFormat.Png);
                 GifPic.AddFrame(Image.FromStream(BmpMemory));
                 BmpMemory = new MemoryStream();
             }
             GifPic.OutPut(ref BmpMemory);
             HttpContext.Current.Response.ClearContent();
             //配置输出类型
             HttpContext.Current.Response.ContentType = "image/Gif";
             //输出内容
             HttpContext.Current.Response.BinaryWrite(BmpMemory.ToArray());
             BmpMemory.Close();
             BmpMemory.Dispose();
         }
         //输出验证码
         public void OutPutValidate(string ValidateCodeSession)
         {
             CreateValidate();
             CreateImageGif();
             //把生成的验证码输入到SESSION
             HttpContext.Current.Session[ValidateCodeSession] = ValidateCode;
         }
     }
}