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diff --git a/libraries/rainbow/src/rainbow.cpp b/libraries/rainbow/src/rainbow.cpp
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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);
+}