CaptchaGenerator.cpp

//this file is part of eMule
//Copyright (C)2002-2008 Merkur ( strEmail.Format("%s@%s", "devteam", "emule-project.net") / http://www.emule-project.net )
//
//This program is free software; you can redistribute it and/or
//modify it under the terms of the GNU General Public License
//as published by the Free Software Foundation; either
//version 2 of the License, or (at your option) any later version.
//
//This program is distributed in the hope that it will be useful,
//but WITHOUT ANY WARRANTY; without even the implied warranty of
//MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	See the
//GNU General Public License for more details.
//
//You should have received a copy of the GNU General Public License
//along with this program; if not, write to the Free Software
//Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

#include "StdAfx.h"
#include "CaptchaGenerator.h"
#include "CxImage/xImage.h"
#include "OtherFunctions.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif


#define LETTERSIZE  32
#define CROWDEDSIZE 18

// fairly simply captcha generator, might be improved is spammers think its really worth it solving captchas on eMule

static const char schCaptchaContent[34] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L'
, 'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '1', '2', '3', '4', '5', '6', '7', '8', '9'};

CCaptchaGenerator::CCaptchaGenerator(uint32 nLetterCount)
{
	m_pimgCaptcha = NULL;
	ReGenerateCaptcha(nLetterCount);
}

CCaptchaGenerator::~CCaptchaGenerator(void)
{
	Clear();
}

void CCaptchaGenerator::ReGenerateCaptcha(uint32 nLetterCount)
{
	Clear();
	CxImage* pimgResult = new CxImage(nLetterCount > 1 ? (LETTERSIZE + (nLetterCount-1)*CROWDEDSIZE) : LETTERSIZE, 32, 1, CXIMAGE_FORMAT_BMP);
	pimgResult->SetPaletteColor(0, 255, 255, 255);
	pimgResult->SetPaletteColor(1, 0, 0, 0, 0);
	pimgResult->Clear();
	CxImage imgBlank(LETTERSIZE, LETTERSIZE, 1, CXIMAGE_FORMAT_BMP);	
	imgBlank.SetPaletteColor(0, 255, 255, 255);
	imgBlank.SetPaletteColor(1, 0, 0, 0, 0);
	imgBlank.Clear();
	for (uint32 i = 0; i < nLetterCount; i++) {
		CxImage imgLetter(imgBlank);
		
		CString strLetter(schCaptchaContent[GetRandomUInt16() % ARRSIZE(schCaptchaContent)]);
		m_strCaptchaText += strLetter;
		
		uint16 nRandomSize = GetRandomUInt16() % 10;
		uint16 nRandomOffset = 3 + GetRandomUInt16() % 11;
		imgLetter.DrawString(NULL, nRandomOffset, 32, strLetter, imgLetter.RGBtoRGBQUAD(RGB(0, 0, 0)), _T("Arial"), 40 - nRandomSize, 1000);
		//imgLetter.DrawTextA(NULL, nRandomOffset, 32, strLetter, imgLetter.RGBtoRGBQUAD(RGB(0, 0, 0)), "Arial", 40 - nRandomSize, 1000);
		float fRotate = (float)(35 - (GetRandomUInt16() % 70));
		imgLetter.Rotate2(fRotate, NULL, CxImage::IM_BILINEAR,  CxImage::OM_BACKGROUND, 0, false, true);
		uint32 nOffset = i * CROWDEDSIZE; 
		ASSERT( imgLetter.GetHeight() == pimgResult->GetHeight() && pimgResult->GetWidth() >= nOffset + imgLetter.GetWidth() );
		for (uint32 j = 0; j < imgLetter.GetHeight(); j++)
			for (uint32 k = 0; k < imgLetter.GetWidth(); k++)
				if (pimgResult->GetPixelIndex(nOffset + k, j) != 1)
					pimgResult->SetPixelIndex(nOffset + k, j, imgLetter.GetPixelIndex(k, j));
	}
	pimgResult->Jitter(1);
	//pimgResult->Save("D:\\CaptchaTest.bmp", CXIMAGE_FORMAT_BMP);
	m_pimgCaptcha = pimgResult;
}

void CCaptchaGenerator::Clear(){
	delete m_pimgCaptcha;
	m_pimgCaptcha = NULL;
	m_strCaptchaText = _T("");
}

bool CCaptchaGenerator::WriteCaptchaImage(CFileDataIO& file)
{
	if (m_pimgCaptcha == NULL)
		return false;
	BYTE* pbyBuffer = NULL;
	long ulSize = 0;
	if (m_pimgCaptcha->Encode(pbyBuffer, ulSize, CXIMAGE_FORMAT_BMP)){
		file.Write(pbyBuffer, ulSize);
		ASSERT( ulSize > 100 && ulSize < 1000 );
		free(pbyBuffer);
		return true;
	}
	else
		return false;
}