src/CaptchaGenerator.cpp

   1 //
   2 // This file is part of the aMule Project.
   3 //
   4 // Copyright (c) 2003-2008 aMule Team ( admin@amule.org / http://www.amule.org )
   5 // Copyright (c) 2002-2008 Merkur ( devs@emule-project.net / http://www.emule-project.net )
   6 //
   7 // Any parts of this program derived from the xMule, lMule or eMule project,
   8 // or contributed by third-party developers are copyrighted by their
   9 // respective authors.
  10 //
  11 // This program is free software; you can redistribute it and/or modify
  12 // it under the terms of the GNU General Public License as published by
  13 // the Free Software Foundation; either version 2 of the License, or
  14 // (at your option) any later version.
  15 //
  16 // This program is distributed in the hope that it will be useful,
  17 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 // GNU General Public License for more details.
  20 //
  21 // You should have received a copy of the GNU General Public License
  22 // along with this program; if not, write to the Free Software
  23 // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA
  24 //
  25
  26 #include "CaptchaGenerator.h"
  27 #include "RandomFunctions.h"
  28 #include "MemFile.h"
  29 #include <wx/bitmap.h>
  30 #include <wx/dcmemory.h>
  31 #include <wx/font.h>
  32
  33
  34 #define LETTERSIZE  32
  35 #define CROWDEDSIZE 20
  36
  37 // fairly simply captcha generator, might be improved is spammers think its really worth it solving captchas on aMule
  38
  39 CCaptchaGenerator::CCaptchaGenerator(uint32 nLetterCount)
  40 {
  41         ReGenerateCaptcha(nLetterCount);
  42 }
  43
  44 void CCaptchaGenerator::ReGenerateCaptcha(uint32 nLetterCount)
  45 {
  46         static wxString schCaptchaContent = wxT("ABCDEFGHJKLMNPQRSTUVWXYZ123456789");
  47         m_strCaptchaText = wxT("");
  48         // Bitmap must be created with full depth, or it will fail on GTK
  49         wxBitmap pimgResult(LETTERSIZE + (nLetterCount-1)*CROWDEDSIZE, 36);
  50         wxMemoryDC dc(pimgResult);
  51         dc.SetBackground(*wxWHITE_BRUSH);
  52         dc.Clear();
  53         dc.SetTextForeground(*wxBLACK);
  54         dc.SetTextBackground(*wxWHITE);
  55         double lastrotate = 15.0;
  56
  57         for (uint32 i = 0; i < nLetterCount; i++) {
  58                 wxString strLetter(schCaptchaContent[GetRandomUint16() % schCaptchaContent.length()]);
  59                 m_strCaptchaText += strLetter;
  60
  61                 uint16 nRandomSize = 30 - GetRandomUint16() % 12;
  62                 wxFont font(nRandomSize, wxFONTFAMILY_SWISS, wxFONTSTYLE_NORMAL, wxFONTWEIGHT_BOLD);
  63                 dc.SetFont(font);
  64                 uint16 nRandomOffset = 3 + GetRandomUint16() % 8;
  65                 uint16 maxRotate = 50 - nRandomSize; // rotate small letters more than large letters
  66                 double fRotate = (double)(maxRotate - (GetRandomUint16() % (maxRotate*2)));
  67                 // limit angle diff - it causes too much overlap since wx rotates at the corner
  68                 // (maybe I'll redo that with some coordinate transformation one day)
  69                 if (fRotate - lastrotate > 20) {
  70                         fRotate = lastrotate + 20;
  71                 } else if (fRotate - lastrotate < -20) {
  72                         fRotate = lastrotate - 20;
  73                 }
  74                 dc.DrawRotatedText(strLetter, nRandomOffset + i * CROWDEDSIZE, 0, fRotate);
  75         }
  76         m_pimgCaptcha = pimgResult.ConvertToImage();
  77         // wx always saves as 24 bpp except when it gets this WELL DOCUMENTED option...
  78         m_pimgCaptcha.SetOption(wxIMAGE_OPTION_BMP_FORMAT, wxBMP_1BPP);
  79         // m_pimgCaptcha.SaveFile(wxT("captcha.bmp"), wxBITMAP_TYPE_BMP);
  80 }
  81
  82 bool CCaptchaGenerator::WriteCaptchaImage(wxMemoryOutputStream& file)
  83 {
  84         return m_pimgCaptcha.SaveFile(file, wxBITMAP_TYPE_BMP);
  85 }