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sneedmc/libraries/rainbow/src/rainbow.cpp
Petr Mrázek bbb3b3e6f6 NOISSUE tabs -> spaces
2018-07-15 14:51:05 +02:00

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/* This was part of the KDE project - see KGuiAddons
* Copyright (C) 2007 Matthew Woehlke <mw_triad@users.sourceforge.net>
* Copyright (C) 2007 Olaf Schmidt <ojschmidt@kde.org>
* Copyright (C) 2007 Thomas Zander <zander@kde.org>
* Copyright (C) 2007 Zack Rusin <zack@kde.org>
* Copyright (C) 2015 Petr Mrazek <peterix@gmail.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#include "../include/rainbow.h"
#include <QColor>
#include <QImage>
#include <QtNumeric> // qIsNaN
#include <math.h>
//BEGIN internal helper functions
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));
}
// normalize: like qBound(a, 0.0, 1.0) but without needing the args and with
// "safer" behavior on NaN (isnan(a) -> return 0.0)
static inline qreal normalize(qreal a)
{
return (a < 1.0 ? (a > 0.0 ? a : 0.0) : 1.0);
}
///////////////////////////////////////////////////////////////////////////////
// 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
class KHCY
{
public:
explicit 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));
}
}
explicit KHCY(qreal h_, qreal c_, qreal y_, qreal a_ = 1.0)
{
h = h_;
c = c_;
y = y_;
a = a_;
}
QColor 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, th, 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, to, 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 h, c, y, a;
static qreal luma(const QColor &color)
{
return lumag(gamma(color.redF()), gamma(color.greenF()), gamma(color.blueF()));
}
private:
static qreal gamma(qreal n)
{
return pow(normalize(n), 2.2);
}
static qreal igamma(qreal n)
{
return pow(normalize(n), 1.0 / 2.2);
}
static qreal lumag(qreal r, qreal g, qreal b)
{
return r * yc[0] + g * yc[1] + b * yc[2];
}
};
static inline qreal mixQreal(qreal a, qreal b, qreal bias)
{
return a + (b - a) * bias;
}
//END internal helper functions
qreal Rainbow::luma(const QColor &color)
{
return KHCY::luma(color);
}
void Rainbow::getHcy(const QColor &color, qreal *h, qreal *c, qreal *y, qreal *a)
{
if (!c || !h || !y)
{
return;
}
KHCY khcy(color);
*c = khcy.c;
*h = khcy.h;
*y = khcy.y;
if (a)
{
*a = khcy.a;
}
}
static qreal contrastRatioForLuma(qreal y1, qreal y2)
{
if (y1 > y2)
{
return (y1 + 0.05) / (y2 + 0.05);
}
else
{
return (y2 + 0.05) / (y1 + 0.05);
}
}
qreal Rainbow::contrastRatio(const QColor &c1, const QColor &c2)
{
return contrastRatioForLuma(luma(c1), luma(c2));
}
QColor Rainbow::lighten(const QColor &color, qreal ky, qreal kc)
{
KHCY c(color);
c.y = 1.0 - normalize((1.0 - c.y) * (1.0 - ky));
c.c = 1.0 - normalize((1.0 - c.c) * kc);
return c.qColor();
}
QColor Rainbow::darken(const QColor &color, qreal ky, qreal kc)
{
KHCY c(color);
c.y = normalize(c.y * (1.0 - ky));
c.c = normalize(c.c * kc);
return c.qColor();
}
QColor Rainbow::shade(const QColor &color, qreal ky, qreal kc)
{
KHCY c(color);
c.y = normalize(c.y + ky);
c.c = normalize(c.c + kc);
return c.qColor();
}
static QColor tintHelper(const QColor &base, qreal baseLuma, const QColor &color, qreal amount)
{
KHCY result(Rainbow::mix(base, color, pow(amount, 0.3)));
result.y = mixQreal(baseLuma, result.y, amount);
return result.qColor();
}
QColor Rainbow::tint(const QColor &base, const QColor &color, qreal amount)
{
if (amount <= 0.0)
{
return base;
}
if (amount >= 1.0)
{
return color;
}
if (qIsNaN(amount))
{
return base;
}
qreal baseLuma = luma(base); // cache value because luma call is expensive
double ri = contrastRatioForLuma(baseLuma, luma(color));
double rg = 1.0 + ((ri + 1.0) * amount * amount * amount);
double u = 1.0, l = 0.0;
QColor result;
for (int i = 12; i; --i)
{
double a = 0.5 * (l + u);
result = tintHelper(base, baseLuma, color, a);
double ra = contrastRatioForLuma(baseLuma, luma(result));
if (ra > rg)
{
u = a;
}
else
{
l = a;
}
}
return result;
}
QColor Rainbow::mix(const QColor &c1, const QColor &c2, qreal bias)
{
if (bias <= 0.0)
{
return c1;
}
if (bias >= 1.0)
{
return c2;
}
if (qIsNaN(bias))
{
return c1;
}
qreal r = mixQreal(c1.redF(), c2.redF(), bias);
qreal g = mixQreal(c1.greenF(), c2.greenF(), bias);
qreal b = mixQreal(c1.blueF(), c2.blueF(), bias);
qreal a = mixQreal(c1.alphaF(), c2.alphaF(), bias);
return QColor::fromRgbF(r, g, b, a);
}
QColor Rainbow::overlayColors(const QColor &base, const QColor &paint,
QPainter::CompositionMode comp)
{
// This isn't the fastest way, but should be "fast enough".
// It's also the only safe way to use QPainter::CompositionMode
QImage img(1, 1, QImage::Format_ARGB32_Premultiplied);
QPainter p(&img);
QColor start = base;
start.setAlpha(255); // opaque
p.fillRect(0, 0, 1, 1, start);
p.setCompositionMode(comp);
p.fillRect(0, 0, 1, 1, paint);
p.end();
return img.pixel(0, 0);
}
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