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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.
*/
#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);
}
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