gradient.h

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/**************************************************************************
* This file is part of the Fraqtive program.
* Copyright (C) 2005 Michal Mecinski.
* This program is licensed under the GNU General Public License.
**************************************************************************/
 
#ifndef GRADIENT_H
#define GRADIENT_H
 
#include "spline.h"
 
#include <qstring.h>
#include <qcolor.h>
 
static const int GRADIENT_LENGTH = 4096;

class Gradient
{
public:
        Gradient();

        Gradient(bool hsv);

        ~Gradient();
 
public:
        bool isHsv() const
        {
                return _isHsv;
        }

        const Spline& getSpline(int index) const
        {
                return _spline[index];
        }

        Spline& getSpline(int index)
        {
                return _spline[index];
        }

        void fillGradient(QRgb* buffer, int length = GRADIENT_LENGTH, double* data = NULL, bool withAlpha = false) const;

        void invert();

        static QRgb hsvToRgb(double h, double s, double v)
        {
                double r, g, b;
 
                double sb = 128.0 * (1.0 - s);
                double va, vb;
                if (v > 0.5) {
                        va = 2.0 - 2.0 * v;
                        vb = 510.0 * v - 255.0;
                } else {
                        va = 2.0 * v;
                        vb = 0.0;
                }
 
                int hh = (int)(6.0 * h);
                double f = 6.0 * h - (double)hh;
                if (hh & 1)
                        f = 1.0 - f;
 
                double m = (255.0 * s + sb) * va + vb;
                double n = sb * va + vb;
                double p = (255.0 * f * s + sb) * va + vb;
 
                switch (hh) {
                case 0: r = m; g = p; b = n; break;
                case 1: r = p; g = m; b = n; break;
                case 2: r = n; g = m; b = p; break;
                case 3: r = n; g = p; b = m; break;
                case 4: r = p; g = n; b = m; break;
                case 5: r = m; g = n; b = p; break;
                default: r = m; g = n; b = n; break;
                }
 
                return qRgb((int)r, (int)g, (int)b);
        }
 
        void fromString( const std::string & grad_def );
 
private:
        bool _isHsv;
        Spline _spline[4];
};
 
#endif