1 files changed, 160 insertions, 0 deletions
diff --git a/libraries/rainbow/include/rainbow.h b/libraries/rainbow/include/rainbow.h
new file mode 100644
index 00000000..b12052b1
--- /dev/null
+++ b/libraries/rainbow/include/rainbow.h
@@ -0,0 +1,160 @@
+/* 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.
+ */
+
+#pragma once
+
+#include "rainbow_config.h"
+
+#include <QPainter>
+class QColor;
+
+/**
+ * A set of methods used to work with colors.
+ */
+namespace Rainbow
+{
+/**
+ * Calculate the luma of a color. Luma is weighted sum of gamma-adjusted
+ * R'G'B' components of a color. The result is similar to qGray. The range
+ * is from 0.0 (black) to 1.0 (white).
+ *
+ * Rainbow::darken(), Rainbow::lighten() and Rainbow::shade()
+ * operate on the luma of a color.
+ *
+ * @see http://en.wikipedia.org/wiki/Luma_(video)
+ */
+RAINBOW_EXPORT qreal luma(const QColor &);
+
+/**
+ * Calculate hue, chroma and luma of a color in one call.
+ * @since 5.0
+ */
+RAINBOW_EXPORT void getHcy(const QColor &, qreal *hue, qreal *chroma, qreal *luma,
+						   qreal *alpha = 0);
+
+/**
+ * Calculate the contrast ratio between two colors, according to the
+ * W3C/WCAG2.0 algorithm, (Lmax + 0.05)/(Lmin + 0.05), where Lmax and Lmin
+ * are the luma values of the lighter color and the darker color,
+ * respectively.
+ *
+ * A contrast ration of 5:1 (result == 5.0) is the minimum for "normal"
+ * text to be considered readable (large text can go as low as 3:1). The
+ * ratio ranges from 1:1 (result == 1.0) to 21:1 (result == 21.0).
+ *
+ * @see Rainbow::luma
+ */
+RAINBOW_EXPORT qreal contrastRatio(const QColor &, const QColor &);
+
+/**
+ * Adjust the luma of a color by changing its distance from white.
+ *
+ * @li amount == 1.0 gives white
+ * @li amount == 0.5 results in a color whose luma is halfway between 1.0
+ * and that of the original color
+ * @li amount == 0.0 gives the original color
+ * @li amount == -1.0 gives a color that is 'twice as far from white' as
+ * the original color, that is luma(result) == 1.0 - 2*(1.0 - luma(color))
+ *
+ * @param amount factor by which to adjust the luma component of the color
+ * @param chromaInverseGain (optional) factor by which to adjust the chroma
+ * component of the color; 1.0 means no change, 0.0 maximizes chroma
+ * @see Rainbow::shade
+ */
+RAINBOW_EXPORT QColor
+lighten(const QColor &, qreal amount = 0.5, qreal chromaInverseGain = 1.0);
+
+/**
+ * Adjust the luma of a color by changing its distance from black.
+ *
+ * @li amount == 1.0 gives black
+ * @li amount == 0.5 results in a color whose luma is halfway between 0.0
+ * and that of the original color
+ * @li amount == 0.0 gives the original color
+ * @li amount == -1.0 gives a color that is 'twice as far from black' as
+ * the original color, that is luma(result) == 2*luma(color)
+ *
+ * @param amount factor by which to adjust the luma component of the color
+ * @param chromaGain (optional) factor by which to adjust the chroma
+ * component of the color; 1.0 means no change, 0.0 minimizes chroma
+ * @see Rainbow::shade
+ */
+RAINBOW_EXPORT QColor darken(const QColor &, qreal amount = 0.5, qreal chromaGain = 1.0);
+
+/**
+ * Adjust the luma and chroma components of a color. The amount is added
+ * to the corresponding component.
+ *
+ * @param lumaAmount amount by which to adjust the luma component of the
+ * color; 0.0 results in no change, -1.0 turns anything black, 1.0 turns
+ * anything white
+ * @param chromaAmount (optional) amount by which to adjust the chroma
+ * component of the color; 0.0 results in no change, -1.0 minimizes chroma,
+ * 1.0 maximizes chroma
+ * @see Rainbow::luma
+ */
+RAINBOW_EXPORT QColor shade(const QColor &, qreal lumaAmount, qreal chromaAmount = 0.0);
+
+/**
+ * Create a new color by tinting one color with another. This function is
+ * meant for creating additional colors withings the same class (background,
+ * foreground) from colors in a different class. Therefore when @p amount
+ * is low, the luma of @p base is mostly preserved, while the hue and
+ * chroma of @p color is mostly inherited.
+ *
+ * @param base color to be tinted
+ * @param color color with which to tint
+ * @param amount how strongly to tint the base; 0.0 gives @p base,
+ * 1.0 gives @p color
+ */
+RAINBOW_EXPORT QColor tint(const QColor &base, const QColor &color, qreal amount = 0.3);
+
+/**
+ * Blend two colors into a new color by linear combination.
+ * @code
+	QColor lighter = Rainbow::mix(myColor, Qt::white)
+ * @endcode
+ * @param c1 first color.
+ * @param c2 second color.
+ * @param bias weight to be used for the mix. @p bias <= 0 gives @p c1,
+ * @p bias >= 1 gives @p c2. @p bias == 0.5 gives a 50% blend of @p c1
+ * and @p c2.
+ */
+RAINBOW_EXPORT QColor mix(const QColor &c1, const QColor &c2, qreal bias = 0.5);
+
+/**
+ * Blend two colors into a new color by painting the second color over the
+ * first using the specified composition mode.
+ * @code
+	QColor white(Qt::white);
+	white.setAlphaF(0.5);
+	QColor lighter = Rainbow::overlayColors(myColor, white);
+   @endcode
+ * @param base the base color (alpha channel is ignored).
+ * @param paint the color to be overlayed onto the base color.
+ * @param comp the CompositionMode used to do the blending.
+ */
+RAINBOW_EXPORT QColor
+overlayColors(const QColor &base, const QColor &paint,
+			  QPainter::CompositionMode comp = QPainter::CompositionMode_SourceOver);
+}