/// <summary>

    /// 验证码类

    /// </summary>

    public class Rand

    {

        #region 生成随机数字

        /// <summary>

        /// 生成随机数字

        /// </summary>

        /// <param name="length">生成长度</param>

        public static string Number(int Length)

        {

            return Number(Length, false);

        }

        /// <summary>

        /// 生成随机数字

        /// </summary>

        /// <param name="Length">生成长度</param>

        /// <param name="Sleep">是否要在生成前将当前线程阻止以避免重复</param>

        public static string Number(int Length, bool Sleep)

        {

            if (Sleep) System.Threading.Thread.Sleep();

            string result = "";

            System.Random random = new Random();

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

            {

                result += random.Next().ToString();

            }

            return result;

        }

        #endregion

        #region 生成随机字母与数字

        /// <summary>

        /// 生成随机字母与数字

        /// </summary>

        /// <param name="IntStr">生成长度</param>

        public static string Str(int Length)

        {

            return Str(Length, false);

        }

        /// <summary>

        /// 生成随机字母与数字

        /// </summary>

        /// <param name="Length">生成长度</param>

        /// <param name="Sleep">是否要在生成前将当前线程阻止以避免重复</param>

        public static string Str(int Length, bool Sleep)

        {

            if (Sleep) System.Threading.Thread.Sleep();

            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 = ; i < Length; i++)

            {

                int rnd = random.Next(, n);

                result += Pattern[rnd];

            }

            return result;

        }

        #endregion

        #region 生成随机纯字母随机数

        /// <summary>

        /// 生成随机纯字母随机数

        /// </summary>

        /// <param name="IntStr">生成长度</param>

        public static string Str_char(int Length)

        {

            return Str_char(Length, false);

        }

        /// <summary>

        /// 生成随机纯字母随机数

        /// </summary>

        /// <param name="Length">生成长度</param>

        /// <param name="Sleep">是否要在生成前将当前线程阻止以避免重复</param>

        public static string Str_char(int Length, bool Sleep)

        {

            if (Sleep) System.Threading.Thread.Sleep();

            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 = ; i < Length; i++)

            {

                int rnd = random.Next(, n);

                result += Pattern[rnd];

            }

            return result;

        }

        #endregion

    }

    /// <summary>

    /// 验证图片类

    /// </summary>

    public class YZMHelper

    {

        #region 私有字段

        private string text;

        private Bitmap image;

        private int letterCount = ;   //验证码位数

        private int letterWidth = ;  //单个字体的宽度范围

        private int letterHeight = ; //单个字体的高度范围

        private static byte[] randb = new byte[];

        private static RNGCryptoServiceProvider rand = new RNGCryptoServiceProvider();

        private Font[] fonts =

    {

       new Font(new FontFamily("Times New Roman"), +Next(),System.Drawing.FontStyle.Regular),

       new Font(new FontFamily("Georgia"),  + Next(),System.Drawing.FontStyle.Regular),

       new Font(new FontFamily("Arial"),  + Next(),System.Drawing.FontStyle.Regular),

       new Font(new FontFamily("Comic Sans MS"),  + Next(),System.Drawing.FontStyle.Regular)

    };

        #endregion

        #region 公有属性

        /// <summary>

        /// 验证码

        /// </summary>

        public string Text

        {

            get { return this.text; }

        }

        /// <summary>

        /// 验证码图片

        /// </summary>

        public Bitmap Image

        {

            get { return this.image; }

        }

        #endregion

        #region 构造函数

        public YZMHelper()

        {

            HttpContext.Current.Response.Expires = ;

            HttpContext.Current.Response.Buffer = true;

            HttpContext.Current.Response.ExpiresAbsolute = DateTime.Now.AddSeconds(-);

            HttpContext.Current.Response.AddHeader("pragma", "no-cache");

            HttpContext.Current.Response.CacheControl = "no-cache";

            this.text = Rand.Number();

            CreateImage();

        }

        #endregion

        #region 私有方法

        /// <summary>

        /// 获得下一个随机数

        /// </summary>

        /// <param name="max">最大值</param>

        private static int Next(int max)

        {

            rand.GetBytes(randb);

            int value = BitConverter.ToInt32(randb, );

            value = value % (max + );

            if (value < ) value = -value;

            return value;

        }

        /// <summary>

        /// 获得下一个随机数

        /// </summary>

        /// <param name="min">最小值</param>

        /// <param name="max">最大值</param>

        private static int Next(int min, int max)

        {

            int value = Next(max - min) + min;

            return value;

        }

        #endregion

        #region 公共方法

        /// <summary>

        /// 绘制验证码

        /// </summary>

        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 = ; i < ; i++)

            {

                int x1 = Next(image.Width - );

                int x2 = Next(image.Width - );

                int y1 = Next(image.Height - );

                int y2 = Next(image.Height - );

                g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);

            }

            int _x = -, _y = ;

            for (int int_index = ; int_index < this.text.Length; int_index++)

            {

                _x += Next(, );

                _y = Next(-, );

                string str_char = this.text.Substring(int_index, );

                str_char = Next() ==  ? 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 - )], newBrush, thePos);

            }

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

            {

                int x = Next(image.Width - );

                int y = Next(image.Height - );

                image.SetPixel(x, y, Color.FromArgb(Next(, ), Next(, ), Next(, )));

            }

            image = TwistImage(image, true, Next(, ), Next(, ));

            g.DrawRectangle(new Pen(Color.LightGray, ), , , int_ImageWidth - , (letterHeight - ));

            this.image = image;

        }

        /// <summary>

        /// 字体随机颜色

        /// </summary>

        public Color GetRandomColor()

        {

            Random RandomNum_First = new Random((int)DateTime.Now.Ticks);

            System.Threading.Thread.Sleep(RandomNum_First.Next());

            Random RandomNum_Sencond = new Random((int)DateTime.Now.Ticks);

            int int_Red = RandomNum_First.Next();

            int int_Green = RandomNum_Sencond.Next();

            int int_Blue = (int_Red + int_Green > ) ?  :  - int_Red - int_Green;

            int_Blue = (int_Blue > ) ?  : int_Blue;

            return Color.FromArgb(int_Red, int_Green, int_Blue);

        }

        /// <summary>

        /// 正弦曲线Wave扭曲图片

        /// </summary>

        /// <param name="srcBmp">图片路径</param>

        /// <param name="bXDir">如果扭曲则选择为True</param>

        /// <param name="nMultValue">波形的幅度倍数，越大扭曲的程度越高,一般为3</param>

        /// <param name="dPhase">波形的起始相位,取值区间[0-2*PI)</param>

        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), , , destBmp.Width, destBmp.Height);

            graph.Dispose();

            double dBaseAxisLen = bXDir ? (double)destBmp.Height : (double)destBmp.Width;

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

            {

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

                {

                    double dx = ;

                    dx = bXDir ? (PI * (double)j) / dBaseAxisLen : (PI * (double)i) / dBaseAxisLen;

                    dx += dPhase;

                    double dy = Math.Sin(dx);

                    int nOldX = , nOldY = ;

                    nOldX = bXDir ? i + (int)(dy * dMultValue) : i;

                    nOldY = bXDir ? j : j + (int)(dy * dMultValue);

                    Color color = srcBmp.GetPixel(i, j);

                    if (nOldX >=  && nOldX < destBmp.Width

                     && nOldY >=  && nOldY < destBmp.Height)

                    {

                        destBmp.SetPixel(nOldX, nOldY, color);

                    }

                }

            }

            srcBmp.Dispose();

            return destBmp;

        }

        #endregion

    }