Color.h

/*
   This file is part of memview, a real-time memory trace visualization
   application.

   Copyright (C) 2013 Andrew Clinton

   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., 59 Temple Place, Suite 330, Boston, MA
   02111-1307, USA.

   The GNU General Public License is contained in the file COPYING.
*/

#ifndef Color_H
#define Color_H

#include <QColor>

class Color {
public:
    Color()
        : myR(0), myG(0), myB(0) {}
    Color(float r, float g, float b)
        : myR(r), myG(g), myB(b) {}
    Color(uint32 val)
    {
        myB = (val & 0xFF) / 255.0F; val >>= 8;
        myG = (val & 0xFF) / 255.0F; val >>= 8;
        myR = (val & 0xFF) / 255.0F;
    }

    uint32      toInt32() const
                {
                    return 0xFF000000 |
                        (ftoc(myB) << 16) |
                        (ftoc(myG) << 8) |
                        (ftoc(myR));
                }

    float       luminance() const
                {
                    return 0.3*myR + 0.6*myG + 0.1*myB;
                }

    Color       operator+(const Color &rhs) const
                {
                    return Color(
                            myR+rhs.myR,
                            myG+rhs.myG,
                            myB+rhs.myB);
                }
    Color       operator*(float scale) const
                {
                    return Color(myR*scale, myG*scale, myB*scale);
                }
    Color       lerp(const Color &rhs, float bias) const
                {
                    QColor  c1(QColor(toInt32()).toHsv());
                    QColor  c2(QColor(rhs.toInt32()).toHsv());

                    // Lerp in HSV space
                    float   h = lerpHue((float)c1.hsvHueF(),
                                        (float)c2.hsvHueF(), bias);
                    float   s = SYSlerp((float)c1.hsvSaturationF(),
                                        (float)c2.hsvSaturationF(), bias);
                    float   l = SYSlerp((float)c1.lightnessF(),
                                        (float)c2.lightnessF(), bias);

                    QColor  c3(QColor::fromHsvF(h, s, l));

                    return Color(c3.redF(), c3.greenF(), c3.blueF());
                }

    void        fromHSV(float h, float s, float v)
                {
                    QColor  c(QColor::fromHsvF(h, s, v));

                    *this = Color(c.redF(), c.greenF(), c.blueF());
                }

private:
    static uint32 ftoc(float v)
                {
                    v *= 255.0F;
                    return SYSclamp((int)v, 0, 255);
                }

    static float    lerpHue(float h1, float h2, float bias)
                    {
                        h1 = SYSclamp(h1, 0.0F, 1.0F);
                        h2 = SYSclamp(h2, 0.0F, 1.0F);
                        if (h2 > h1 + 0.5F)
                            h1 += 1;
                        else if (h1 > h2 + 0.5F)
                            h2 += 1;

                        float   h = SYSlerp(h1, h2, bias);
                        if (h > 1) h -= 1;
                        return h;
                    }


private:
    float        myR;
    float        myG;
    float        myB;
};

#endif