//---------------------------------------------------------------------------- // Anti-Grain Geometry - Version 2.4 // Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com) // // Permission to copy, use, modify, sell and distribute this software // is granted provided this copyright notice appears in all copies. // This software is provided "as is" without express or implied // warranty, and with no claim as to its suitability for any purpose. // //---------------------------------------------------------------------------- // Contact: mcseem@antigrain.com // mcseemagg@yahoo.com // http://www.antigrain.com //---------------------------------------------------------------------------- #ifndef AGG_GAMMA_FUNCTIONS_INCLUDED #define AGG_GAMMA_FUNCTIONS_INCLUDED #include <cmath> #include "agg_basics.h" namespace agg { //===============================================================gamma_none struct gamma_none { double operator()(double x) const { return x; } }; //==============================================================gamma_power class gamma_power { public: gamma_power() : m_gamma(1.0) {} gamma_power(double g) : m_gamma(g) {} void gamma(double g) { m_gamma = g; } double gamma() const { return m_gamma; } double operator() (double x) const { if (x == 0.0) return 0.0; return pow(x, m_gamma); } private: double m_gamma; }; //==========================================================gamma_threshold class gamma_threshold { public: gamma_threshold() : m_threshold(0.5) {} gamma_threshold(double t) : m_threshold(t) {} void threshold(double t) { m_threshold = t; } double threshold() const { return m_threshold; } double operator() (double x) const { return (x < m_threshold) ? 0.0 : 1.0; } private: double m_threshold; }; //============================================================gamma_linear class gamma_linear { public: gamma_linear() : m_start(0.0), m_end(1.0) {} gamma_linear(double s, double e) : m_start(s), m_end(e) {} void set(double s, double e) { m_start = s; m_end = e; } void start(double s) { m_start = s; } void end(double e) { m_end = e; } double start() const { return m_start; } double end() const { return m_end; } double operator() (double x) const { if(x < m_start) return 0.0; if(x > m_end) return 1.0; double delta = m_end - m_start; // avoid nan from potential zero division // https://github.com/mapnik/mapnik/issues/761 if (delta <= 0.0) return 0.0; return (x - m_start) / delta; } private: double m_start; double m_end; }; //==========================================================gamma_multiply class gamma_multiply { public: gamma_multiply() : m_mul(1.0) {} gamma_multiply(double v) : m_mul(v) {} void value(double v) { m_mul = v; } double value() const { return m_mul; } double operator() (double x) const { double y = x * m_mul; if(y > 1.0) y = 1.0; return y; } private: double m_mul; }; inline double sRGB_to_linear(double x) { return (x <= 0.04045) ? (x / 12.92) : pow((x + 0.055) / (1.055), 2.4); } inline double linear_to_sRGB(double x) { return (x <= 0.0031308) ? (x * 12.92) : (1.055 * pow(x, 1 / 2.4) - 0.055); } } #endif