using System;using System.Web;using System.Drawing;using System.Security.Cryptography;namespace DotNet.Utilities{    /// 
    /// 验证码类    /// 
    public class Rand    {        #region 生成随机数字        /// 
        /// 生成随机数字        /// 
        /// 生成长度        public static string Number(int Length)        {            return Number(Length, false);        }        /// 
        /// 生成随机数字        /// 
        /// 生成长度        /// 是否要在生成前将当前线程阻止以避免重复        public static string Number(int Length, bool Sleep)        {            if (Sleep) System.Threading.Thread.Sleep(3);            string result = "";            System.Random random = new Random();            for (int i = 0; i < Length; i++)            {                result += random.Next(10).ToString();            }            return result;        }        #endregion        #region 生成随机字母与数字        /// 
        /// 生成随机字母与数字        /// 
        /// 生成长度        public static string Str(int Length)        {            return Str(Length, false);        }        /// 
        /// 生成随机字母与数字        /// 
        /// 生成长度        /// 是否要在生成前将当前线程阻止以避免重复        public static string Str(int Length, bool Sleep)        {            if (Sleep) System.Threading.Thread.Sleep(3);            char[] Pattern = new char[] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };            string result = "";            int n = Pattern.Length;            System.Random random = new Random(~unchecked((int)DateTime.Now.Ticks));            for (int i = 0; i < Length; i++)            {                int rnd = random.Next(0, n);                result += Pattern[rnd];            }            return result;        }        #endregion        #region 生成随机纯字母随机数        /// 
        /// 生成随机纯字母随机数        /// 
        /// 生成长度        public static string Str_char(int Length)        {            return Str_char(Length, false);        }        /// 
        /// 生成随机纯字母随机数        /// 
        /// 生成长度        /// 是否要在生成前将当前线程阻止以避免重复        public static string Str_char(int Length, bool Sleep)        {            if (Sleep) System.Threading.Thread.Sleep(3);            char[] Pattern = new char[] { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };            string result = "";            int n = Pattern.Length;            System.Random random = new Random(~unchecked((int)DateTime.Now.Ticks));            for (int i = 0; i < Length; i++)            {                int rnd = random.Next(0, n);                result += Pattern[rnd];            }            return result;        }        #endregion    }    /// 
    /// 验证图片类    /// 
    public class YZMHelper    {        #region 私有字段        private string text;        private Bitmap image;        private int letterCount = 4;   //验证码位数        private int letterWidth = 16;  //单个字体的宽度范围        private int letterHeight = 20; //单个字体的高度范围        private static byte[] randb = new byte[4];        private static RNGCryptoServiceProvider rand = new RNGCryptoServiceProvider();        private Font[] fonts =     {       new Font(new FontFamily("Times New Roman"),10 +Next(1),System.Drawing.FontStyle.Regular),       new Font(new FontFamily("Georgia"), 10 + Next(1),System.Drawing.FontStyle.Regular),       new Font(new FontFamily("Arial"), 10 + Next(1),System.Drawing.FontStyle.Regular),       new Font(new FontFamily("Comic Sans MS"), 10 + Next(1),System.Drawing.FontStyle.Regular)    };        #endregion        #region 公有属性        /// 
        /// 验证码        /// 
        public string Text        {            get { return this.text; }        }        /// 
        /// 验证码图片        /// 
        public Bitmap Image        {            get { return this.image; }        }        #endregion        #region 构造函数        public YZMHelper()        {            HttpContext.Current.Response.Expires = 0;            HttpContext.Current.Response.Buffer = true;            HttpContext.Current.Response.ExpiresAbsolute = DateTime.Now.AddSeconds(-1);            HttpContext.Current.Response.AddHeader("pragma", "no-cache");            HttpContext.Current.Response.CacheControl = "no-cache";            this.text = Rand.Number(4);            CreateImage();        }        #endregion        #region 私有方法        /// 
        /// 获得下一个随机数        /// 
        /// 最大值        private static int Next(int max)        {            rand.GetBytes(randb);            int value = BitConverter.ToInt32(randb, 0);            value = value % (max + 1);            if (value < 0) value = -value;            return value;        }        /// 
        /// 获得下一个随机数        /// 
        /// 最小值        /// 最大值        private static int Next(int min, int max)        {            int value = Next(max - min) + min;            return value;        }        #endregion        #region 公共方法        /// 
        /// 绘制验证码        /// 
        public void CreateImage()        {            int int_ImageWidth = this.text.Length * letterWidth;            Bitmap image = new Bitmap(int_ImageWidth, letterHeight);            Graphics g = Graphics.FromImage(image);            g.Clear(Color.White);            for (int i = 0; i < 2; i++)            {                int x1 = Next(image.Width - 1);                int x2 = Next(image.Width - 1);                int y1 = Next(image.Height - 1);                int y2 = Next(image.Height - 1);                g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);            }            int _x = -12, _y = 0;            for (int int_index = 0; int_index < this.text.Length; int_index++)            {                _x += Next(12, 16);                _y = Next(-2, 2);                string str_char = this.text.Substring(int_index, 1);                str_char = Next(1) == 1 ? str_char.ToLower() : str_char.ToUpper();                Brush newBrush = new SolidBrush(GetRandomColor());                Point thePos = new Point(_x, _y);                g.DrawString(str_char, fonts[Next(fonts.Length - 1)], newBrush, thePos);            }            for (int i = 0; i < 10; i++)            {                int x = Next(image.Width - 1);                int y = Next(image.Height - 1);                image.SetPixel(x, y, Color.FromArgb(Next(0, 255), Next(0, 255), Next(0, 255)));            }            image = TwistImage(image, true, Next(1, 3), Next(4, 6));            g.DrawRectangle(new Pen(Color.LightGray, 1), 0, 0, int_ImageWidth - 1, (letterHeight - 1));            this.image = image;        }        /// 
        /// 字体随机颜色        /// 
        public Color GetRandomColor()        {            Random RandomNum_First = new Random((int)DateTime.Now.Ticks);            System.Threading.Thread.Sleep(RandomNum_First.Next(50));            Random RandomNum_Sencond = new Random((int)DateTime.Now.Ticks);            int int_Red = RandomNum_First.Next(180);            int int_Green = RandomNum_Sencond.Next(180);            int int_Blue = (int_Red + int_Green > 300) ? 0 : 400 - int_Red - int_Green;            int_Blue = (int_Blue > 255) ? 255 : int_Blue;            return Color.FromArgb(int_Red, int_Green, int_Blue);        }        /// 
        /// 正弦曲线Wave扭曲图片        /// 
        /// 图片路径        /// 如果扭曲则选择为True        /// 波形的幅度倍数，越大扭曲的程度越高,一般为3        /// 波形的起始相位,取值区间[0-2*PI)        public System.Drawing.Bitmap TwistImage(Bitmap srcBmp, bool bXDir, double dMultValue, double dPhase)        {            double PI = 6.283185307179586476925286766559;            Bitmap destBmp = new Bitmap(srcBmp.Width, srcBmp.Height);            Graphics graph = Graphics.FromImage(destBmp);            graph.FillRectangle(new SolidBrush(Color.White), 0, 0, destBmp.Width, destBmp.Height);            graph.Dispose();            double dBaseAxisLen = bXDir ? (double)destBmp.Height : (double)destBmp.Width;            for (int i = 0; i < destBmp.Width; i++)            {                for (int j = 0; j < destBmp.Height; j++)                {                    double dx = 0;                    dx = bXDir ? (PI * (double)j) / dBaseAxisLen : (PI * (double)i) / dBaseAxisLen;                    dx += dPhase;                    double dy = Math.Sin(dx);                    int nOldX = 0, nOldY = 0;                    nOldX = bXDir ? i + (int)(dy * dMultValue) : i;                    nOldY = bXDir ? j : j + (int)(dy * dMultValue);                    Color color = srcBmp.GetPixel(i, j);                    if (nOldX >= 0 && nOldX < destBmp.Width                     && nOldY >= 0 && nOldY < destBmp.Height)                    {                        destBmp.SetPixel(nOldX, nOldY, color);                    }                }            }            srcBmp.Dispose();            return destBmp;        }        #endregion    }}