File indexing completed on 2024-12-08 03:39:25

 /*  This file is part of the KDE project
     SPDX-FileCopyrightText: 2007 Matthew Woehlke <mw_triad@users.sourceforge.net>
     SPDX-FileCopyrightText: 2007 Olaf Schmidt <ojschmidt@kde.org>
 
     SPDX-License-Identifier: LGPL-2.0-or-later
 */
 #include "kcolorspaces_p.h"
 #include "kguiaddons_colorhelpers_p.h"
 
 #include <QColor>
 
 #include <math.h>
 
 using namespace KColorSpaces;
 
 static inline qreal wrap(qreal a, qreal d = 1.0)
 {
     qreal r = fmod(a, d);
     return (r < 0.0 ? d + r : (r > 0.0 ? r : 0.0));
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 // HCY color space
 
 #define HCY_REC 709 // use 709 for now
 #if HCY_REC == 601
 static const qreal yc[3] = {0.299, 0.587, 0.114};
 #elif HCY_REC == 709
 static const qreal yc[3] = {0.2126, 0.7152, 0.0722};
 #else // use Qt values
 static const qreal yc[3] = {0.34375, 0.5, 0.15625};
 #endif
 
 qreal KHCY::gamma(qreal n)
 {
     return pow(normalize(n), 2.2);
 }
 
 qreal KHCY::igamma(qreal n)
 {
     return pow(normalize(n), 1.0 / 2.2);
 }
 
 qreal KHCY::lumag(qreal r, qreal g, qreal b)
 {
     return r * yc[0] + g * yc[1] + b * yc[2];
 }
 
 KHCY::KHCY(qreal h_, qreal c_, qreal y_, qreal a_)
 {
     h = h_;
     c = c_;
     y = y_;
     a = a_;
 }
 
 KHCY::KHCY(const QColor &color)
 {
     qreal r = gamma(color.redF());
     qreal g = gamma(color.greenF());
     qreal b = gamma(color.blueF());
     a = color.alphaF();
 
     // luma component
     y = lumag(r, g, b);
 
     // hue component
     qreal p = qMax(qMax(r, g), b);
     qreal n = qMin(qMin(r, g), b);
     qreal d = 6.0 * (p - n);
     if (n == p) {
         h = 0.0;
     } else if (r == p) {
         h = ((g - b) / d);
     } else if (g == p) {
         h = ((b - r) / d) + (1.0 / 3.0);
     } else {
         h = ((r - g) / d) + (2.0 / 3.0);
     }
 
     // chroma component
     if (r == g && g == b) {
         c = 0.0;
     } else {
         c = qMax((y - n) / y, (p - y) / (1 - y));
     }
 }
 
 QColor KHCY::qColor() const
 {
     // start with sane component values
     qreal _h = wrap(h);
     qreal _c = normalize(c);
     qreal _y = normalize(y);
 
     // calculate some needed variables
     qreal _hs = _h * 6.0;
     qreal th;
     qreal tm;
     if (_hs < 1.0) {
         th = _hs;
         tm = yc[0] + yc[1] * th;
     } else if (_hs < 2.0) {
         th = 2.0 - _hs;
         tm = yc[1] + yc[0] * th;
     } else if (_hs < 3.0) {
         th = _hs - 2.0;
         tm = yc[1] + yc[2] * th;
     } else if (_hs < 4.0) {
         th = 4.0 - _hs;
         tm = yc[2] + yc[1] * th;
     } else if (_hs < 5.0) {
         th = _hs - 4.0;
         tm = yc[2] + yc[0] * th;
     } else {
         th = 6.0 - _hs;
         tm = yc[0] + yc[2] * th;
     }
 
     // calculate RGB channels in sorted order
     qreal tn;
     qreal to;
     qreal tp;
     if (tm >= _y) {
         tp = _y + _y * _c * (1.0 - tm) / tm;
         to = _y + _y * _c * (th - tm) / tm;
         tn = _y - (_y * _c);
     } else {
         tp = _y + (1.0 - _y) * _c;
         to = _y + (1.0 - _y) * _c * (th - tm) / (1.0 - tm);
         tn = _y - (1.0 - _y) * _c * tm / (1.0 - tm);
     }
 
     // return RGB channels in appropriate order
     if (_hs < 1.0) {
         return QColor::fromRgbF(igamma(tp), igamma(to), igamma(tn), a);
     } else if (_hs < 2.0) {
         return QColor::fromRgbF(igamma(to), igamma(tp), igamma(tn), a);
     } else if (_hs < 3.0) {
         return QColor::fromRgbF(igamma(tn), igamma(tp), igamma(to), a);
     } else if (_hs < 4.0) {
         return QColor::fromRgbF(igamma(tn), igamma(to), igamma(tp), a);
     } else if (_hs < 5.0) {
         return QColor::fromRgbF(igamma(to), igamma(tn), igamma(tp), a);
     } else {
         return QColor::fromRgbF(igamma(tp), igamma(tn), igamma(to), a);
     }
 }
 
 qreal KHCY::hue(const QColor &color)
 {
     return wrap(KHCY(color).h);
 }
 
 qreal KHCY::chroma(const QColor &color)
 {
     return KHCY(color).c;
 }
 
 qreal KHCY::luma(const QColor &color)
 {
     return lumag(gamma(color.redF()), gamma(color.greenF()), gamma(color.blueF()));
 }