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/*
* SPDX-FileCopyrightText: 2013-2020 Mattia Basaglia
*
* SPDX-License-Identifier: LGPL-3.0-or-later
*/
#ifndef GRADIENT_HELPER_HPP
#define GRADIENT_HELPER_HPP
#include "colorwidgets_global.hpp"
#include <QGradient>
namespace color_widgets {
inline QColor blendColors(const QColor& a, const QColor& b, qreal ratio)
{
return QColor::fromRgbF(
a.redF() * (1-ratio) + b.redF() * ratio,
a.greenF() * (1-ratio) + b.greenF() * ratio,
a.blueF() * (1-ratio) + b.blueF() * ratio,
a.alphaF() * (1-ratio) + b.alphaF() * ratio
);
}
/**
* \brief Get an insertion point in the gradient
* \param gradient Gradient stops to look into (must be properly set up)
* \param factor Value in [0, 1] to get the color for
* \return A pair whose first element is the index to insert the new value at, and a GradientStop
*/
inline QPair<int, QGradientStop> Q_DECL_EXPORT gradientBlendedColorInsert(const QGradientStops& gradient, qreal factor)
{
if ( gradient.empty() )
return {0, {0, QColor()}};
if ( gradient.size() == 1 || factor <= 0 )
return {0, gradient.front()};
int i = 0;
QGradientStop s1;
for ( auto s2 : gradient )
{
if ( factor < s2.first )
{
qreal ratio = (factor - s1.first) / (s2.first - s1.first);
return {i, {factor, blendColors(s1.second, s2.second, ratio)}};
}
s1 = s2;
++i;
}
return {gradient.size(), gradient.back()};
}
/**
* \brief Returns a color in the gradient
* \param gradient Gradient stops to look into (must be properly set up)
* \param factor Value in [0, 1] to get the color for
*/
inline QColor Q_DECL_EXPORT gradientBlendedColor(const QGradientStops& gradient, qreal factor)
{
return gradientBlendedColorInsert(gradient, factor).second.second;
}
/**
* \brief Returns a color in the gradient
* \param gradient Gradient to look into
* \param factor Value in [0, 1] to get the color for
*/
inline QColor Q_DECL_EXPORT gradientBlendedColor(const QGradient& gradient, qreal factor)
{
return gradientBlendedColor(gradient.stops(), factor);
}
} // namespace color_widgets
#endif // GRADIENT_HELPER_HPP
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