The method of making random picture generator

 .net handler generates a random 6-bit picture verification code, we refer to the use of the bar

The code is as follows:///<summary>    ///PicHandler1 Summary description    ///</summary>     public CLA SS Pichandler1:ihttphandler, IRequiresSessionState     {        private string mcheckno = String. Empty;         protected Imgbuilder _imgbuilder = new Imgbuilder ();         protected Vryimggen _imgbuildernew = new Vryimggen ();         private String _text = String. Empty;         private String _font = "Song Body";         private int _fontsize = 8;         private int _padding = 2;         public void ProcessRequest (HttpContext context)         {    &N Bsp       Mcheckno = Discheckno ();             context. session["Checkcode"] = Mcheckno;             this._imgbuilder.fontsize = this._fontsize;             this._imgbuilder.padding = this._padding;               if (!string. IsNullOrEmpty (This._font))             {              &N Bsp this._imgbuilder.fonts = new string[] {This._font};                         this._imgbuildernew.chaoswight = 40;             this._imgbuildernew.fontsize = 25;               this._imgbuildernew.padding = 3;             SYSTEM.DRAWING.BITMAP image =              th Is._imgbuildernew.createimage (Mcheckno);             System.IO.MemoryStream ms = new System.IO.MemoryStream ();             image. Save (MS, System.Drawing.Imaging.ImageFormat.Jpeg);            context. Response.clearcontent ();             context. Response.ContentType = "Image/jpeg";             context. Response.BinaryWrite (Ms. ToArray ());             context. session["Checkcode"] = mcheckno.tostring (); If IRequiresSessionState is not implemented, there will be an error and cannot generate pictures             context. Response.End ();        }          //CAPTCHA code generation         protected string DisC Heckno ()         {            String hash = Hashcode.getnext ();             String checkno = string. Empty;             Random rd = new Random (DateTime.Now.Millisecond);             for (int i = 0; i < 6; i++)             {&nbsp ;               Checkno + = hash. Substring (Rd. Next (1, hash. Length-1), 1);                         Checkno = Checkno.replace ("0", RD. Next (1, 9). ToString ());             Checkno = Checkno.replace ("o", RD. Next (1, 9). ToString ());             Checkno = Checkno.replace ("O", RD. Next (1, 9). ToString ());             return checkno;        }           public bool isreusable         {&nbs P           get             {          &NBS P     return false;            }         {   }         calling class The     code is as follows: using System; Using System.Drawing; Using System.Text;  ///<summary>///Vryimggen Summary description///</summary> PubLic class Vryimggen {    public static string chinesechars = String.Empty;      ///<summary >    ///English with digital string    ///</summary>     protected static readonly string Englishorn Umchars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";       Public Vryimggen ()     {        rnd = new Random (unchecked (int) Dateti Me. Now.ticks));    }      ///<summary>    ///global random number generator    ///</summary> &NB Sp   Private Random Rnd;       INT length = 5;    ///<summary>    ///Verification code Length (default 6 authenticode length)    ///</summary>     Pub LIC int Length     {        get {return Length;}       set {length = value; }    }       int fontsize = 20;    ///<summary>    ///Verification Code font size (for display distortion effect, default 30 pixel, can modify itself)    ///</summary>     public int fontsize   &N Bsp {        get {return fontsize;}         set {fontsize = value}     }       int padding = 4;    ///<summary>    ///Border repair (default 4 pixels)    ///</summary>     public int Padding     {        get {return Padding;}         set {Padding = V Alue; }    }       bool chaos = true;    ///<summary>    ///output dryness point (default output)    ///</summary>     Public b Ool Chaos     {        get {return Chaos;}         set {Chaos = Valu E }    }       Color chaoscolor = Color.lightgray;    ///<summary>    ///output dryness point color (default gray)    </summary>     Public Color Chaoscolor     {        Chaosc Olor; }         set {Chaoscolor = value;}    }       int chaoswight = 1;    ///<summary>    ///output dryness point concentration    ///</summary>     public int Ch Aoswight     {        get {return chaoswight;}         set {Chaoswig HT = value; }    }       Color backgroundcolor = Color.White;    ///<summary>    ///custom background color (default white)    ///</summary>     public C Olor backgroundcolor     {        get {return backgroundcolor;}       &NBS P set {backgroundcolor = value;}    }       color[] colors = {color.black, color.red, Color.dar Kblue, Color.green, Color.orange, Color.brown, Color.darKcyan, color.purple};    ///<summary>    ///custom random color array    ///</summary>     public Colo R[] Colors     {        get {return Colors;}         set {Colors = V Alue; }    }       string[] fonts = {"Arial", "Georgia"};    ///<summary>    ///custom font array    ///</summary>     public string [] Fonts     {        get {return Fonts;}         set {Fonts = value ; {   }       #region generating waveform filter effect       Private Const double PI = 3.14159265358979323 84626433832795;     Private Const double PI2 = 6.283185307179586476925286766559;      ///<summary>    ///sine wave distorted picture (Edit by 51aspx.com)    ///</summary >    ///<param name= "srcbmp" > Picture path </PARAM&GT    ///<param name= "Bxdir" > If the Warp is selected true</param>    ///<param name= "Nmultvalue" > Waveform amplitude Multiples, the greater the degree of distortion, the general 3</param>    ///<param name= "Dphase" > Waveform starting phase, take the value range [0-2*pi) </ param>    ///<returns></returns>     public System.Drawing.Bitmap twistimage ( Bitmap srcbmp, bool Bxdir, double dmultvalue, double dphase)     {        System.Drawing.Bi TMap destbmp = new Bitmap (srcbmp.width, srcbmp.height);          //fill the bitmap background with white         System.Drawing.Graphics graph = System.drawin G.graphics.fromimage (destbmp);         graph. FillRectangle (New SolidBrush (System.Drawing.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; &n Bsp               DX = Bxdir? (PI2 * (double) j)/Dbaseaxislen: (PI2 * (double) i)/Dbaseaxislen;                 DX + dphase;                 Double dy = math.sin (dx);                  //Get current point's color             &NBSP ;   int noldx = 0, Noldy = 0;                 NOLDX = Bxdir? i + (int) (DY * dmultvalue): i;                 Noldy = Bxdir? J:j + (int) (DY * dmultvalue);                   System.draWing. Color color = Srcbmp.getpixel (i, j);                 if (noldx >= 0 && noldx < destbmp.width   &NBSP ;              && noldy >= 0 && Noldy < destbmp.height)   &nbs P             {                    destbmp. SetPixel (NOLDX, noldy, color);                            }        }           return destbmp;    }           #endregion      ///<summary>    /// Parity code Pictures    ///</summary>    ///<param name= "code" > Verification Code </param>    ///& lt;returns></returns>     Public Bitmap createimage (string code)     {      & nbsp INT fsize = fontsize;         int fwidth = fsize + Padding;           int imagewidth = (int) (code. Length * fwidth) + 4 + Padding * 2;         int imageheight = fsize * 2 + Padding * 2;           SYSTEM.DRAWING.BITMAP image = new System.Drawing.Bitmap (imageWidth-10, ImageHeight- 10);           Graphics g = graphics.fromimage (image);           g.clear (backgroundcolor);          //Add randomly generated dryness point to background for         if (this. Chaos)         {              Pen pen = new Pen (chaoscolor, 0); &n Bsp           INT c = chaoswight * 10;               for (int i = 0; i < C; i++)             {                int x = rnd. Next (image. Width); &nbSp               int y = rnd. Next (image. Height);                   G.drawrectangle (pen, x, Y, 1, 1);                     {          int left = 0, top = 0, Top1 = 1, top2 = 1;           int n1 = (imageheight-fontsize-padding * 2);         int n2 = N1/4;         TOP1 = n2;         TOP2 = n2 * 2;           Font F;         Brush B;           int cindex, Findex;          //random font and color verification code character         for (int i = 0; i < code.) Length; i++)         {            CIndex = rnd. Next (colors.length-1);             Findex = rnd. Next (fonts.length-1);   &NBSP           f = new System.Drawing.Font (Fonts[findex], fsize, System.Drawing.FontStyle.Bold);             B = new System.Drawing.SolidBrush (Colors[cindex]);               if (i% 2 = 1)             {                top = TOP2;                         else         &NB Sp   {                top = TOP1,      ,      } & nbsp             left = i * fwidth;               g.drawstring (code. Substring (i, 1), F, B, left, top);        }          /Draw a border border color Color.gainsboro         G.drawrectangle (New Pen (Color.gainsboro, 0), 0, 0, image. Width-1, IMAGe. HEIGHT-1);         g.dispose ();          //Generate waveform (ADD by 51aspx.com)         image = Twistimage (image, True, 8 , 4);           return image;    }      ///<summary>    ///generate random character code    ///</summary> &nbs P  ///<param name= "Codelen" > String length </param>    ///<param name= "Zhcharscount" > Chinese character number </param>    ///<returns></returns>     public string createverifycode (int Codelen, int zhcharscount)     {        char[] CHS = new Char[codelen];     &NBSP ;     INT index;         for (int i = 0; i < Zhcharscount i++)         {      & nbsp     index = rnd. Next (0, Codelen);             if (chs[index] = = ")                 Chs[index] = Createzhchar ();             else                -I.        }         for (int i = 0; i < Codelen; i++)         {            if (chs[i] = = ')                 CHS [I] = Createenornumchar ();        }           return new string (CHS, 0, CHS. Length);    }      ///<summary>    ///Generate default length 5 random character code    ///</summary&gt ;    ///<returns></returns>     public string Createverifycode ()     {  &N Bsp     return Createverifycode (Length, 0);    }      ///<summary>    ///generate English or digital characters    ///</summary> &N Bsp  ///<returns></returns>     protected char Createenornumchar ()     {        return Englishorn Umchars[rnd. Next (0, englishornumchars.length)];    }      ///<summary>    ///generation character    ///</summary> &nbsp ;  ///<returns></returns>     protected char Createzhchar ()     {    &NBSP ;  //If a Chinese character set is provided, query Chinese character set select Chinese characters         if (chinesechars.length > 0)         {&nbsp ;           return CHINESECHARS[RND. Next (0, chinesechars.length)];        }        //If no Chinese character set is provided, the Chinese character     &nbsp   is constructed according to the code rules of the GB2312 Simplified Chinese Code table ; else         {            byte[] bytes = new byte[2];     &NB Sp        //First byte value between 0xb0, 0xf7           bytes[0] = (byte) rnd. Next (0xb0, 0xf8);            //second byte value in 0xa1, 0xFE between             bytes[1] = (byte ) Rnd. Next (0xa1, 0xff);              //decoding from encoding byte array Chinese characters             String str 1 = encoding.getencoding ("gb2312"). GetString (bytes);               return str1[0];        }    }  }