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C++ API DOCUMENTATION |
00001 /***************************************************************************** 00002 * 00003 * This file is part of Mapnik (c++ mapping toolkit) 00004 * 00005 * Copyright (C) 2006 Artem Pavlenko 00006 * 00007 * This library is free software; you can redistribute it and/or 00008 * modify it under the terms of the GNU Lesser General Public 00009 * License as published by the Free Software Foundation; either 00010 * version 2.1 of the License, or (at your option) any later version. 00011 * 00012 * This library is distributed in the hope that it will be useful, 00013 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00015 * Lesser General Public License for more details. 00016 * 00017 * You should have received a copy of the GNU Lesser General Public 00018 * License along with this library; if not, write to the Free Software 00019 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA 00020 * 00021 *****************************************************************************/ 00022 00023 //$Id: gamma.hpp 39 2005-04-10 20:39:53Z pavlenko $ 00024 00025 #ifndef GAMMA_HPP 00026 #define GAMMA_HPP 00027 00028 #include <cmath> 00029 00030 // When using Sun's C++ compiler, use the `std` namespace to get the math routines. 00031 #ifdef __SUNPRO_CC 00032 using std::pow; 00033 #endif 00034 00035 namespace mapnik 00036 { 00037 struct MAPNIK_DECL gamma 00038 { 00039 unsigned char g2l[256]; 00040 unsigned char l2g[256]; 00041 gamma(double gamma=2.0) 00042 { 00043 int result; 00044 for (int i=0;i< 256;i++) 00045 { 00046 result=(int)(pow(i/255.0,gamma) * 255.0 + 0.5); 00047 g2l[i]=(unsigned char)result; 00048 } 00049 for (int i = 0; i < 256; i++) 00050 { 00051 result = (int)(pow(i/255.0, 1/gamma) * 255.0 + 0.5); 00052 l2g[i] = (unsigned char)result; 00053 } 00054 } 00055 }; 00056 } 00057 00058 #endif //GAMMA_HPP