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