File indexing completed on 2024-05-05 04:46:57

 /*
  *  SPDX-FileCopyrightText: 2020 Carson Black <uhhadd@gmail.com>
  *
  *  SPDX-License-Identifier: LGPL-2.0-or-later
  */
 
 #include "colorutils.h"
 
 #include <QIcon>
 #include <QtMath>
 #include <cmath>
 #include <map>
 
 ColorUtils::ColorUtils(QObject *parent)
     : QObject(parent)
 {
 }
 
 ColorUtils::Brightness ColorUtils::brightnessForColor(const QColor &color)
 {
     auto luma = [](const QColor &color) {
         return (0.299 * color.red() + 0.587 * color.green() + 0.114 * color.blue()) / 255;
     };
 
     return luma(color) > 0.5 ? ColorUtils::Brightness::Light : ColorUtils::Brightness::Dark;
 }
 
 qreal ColorUtils::grayForColor(const QColor &color)
 {
     return (0.299 * color.red() + 0.587 * color.green() + 0.114 * color.blue()) / 255;
 }
 
 QColor ColorUtils::alphaBlend(const QColor &foreground, const QColor &background)
 {
     const auto foregroundAlpha = foreground.alpha();
     const auto inverseForegroundAlpha = 0xff - foregroundAlpha;
     const auto backgroundAlpha = background.alpha();
 
     if (foregroundAlpha == 0x00) {
         return background;
     }
 
     if (backgroundAlpha == 0xff) {
         return QColor::fromRgb((foregroundAlpha * foreground.red()) + (inverseForegroundAlpha * background.red()),
                                (foregroundAlpha * foreground.green()) + (inverseForegroundAlpha * background.green()),
                                (foregroundAlpha * foreground.blue()) + (inverseForegroundAlpha * background.blue()),
                                0xff);
     } else {
         const auto inverseBackgroundAlpha = (backgroundAlpha * inverseForegroundAlpha) / 255;
         const auto finalAlpha = foregroundAlpha + inverseBackgroundAlpha;
         Q_ASSERT(finalAlpha != 0x00);
         return QColor::fromRgb((foregroundAlpha * foreground.red()) + (inverseBackgroundAlpha * background.red()),
                                (foregroundAlpha * foreground.green()) + (inverseBackgroundAlpha * background.green()),
                                (foregroundAlpha * foreground.blue()) + (inverseBackgroundAlpha * background.blue()),
                                finalAlpha);
     }
 }
 
 QColor ColorUtils::linearInterpolation(const QColor &one, const QColor &two, double balance)
 {
    auto scaleAlpha = [](const QColor &color, double factor) {
         return QColor::fromRgb(color.red(), color.green(), color.blue(), color.alpha() * factor);
     };
     auto linearlyInterpolateDouble = [](double one, double two, double factor) {
         return one + (two - one) * factor;
     };
 
     if (one == Qt::transparent) {
         return scaleAlpha(two, balance);
     }
     if (two == Qt::transparent) {
         return scaleAlpha(one, 1 - balance);
     }
 
     return QColor::fromHsv(std::fmod(linearlyInterpolateDouble(one.hue(), two.hue(), balance), 360.0),
                            qBound(0.0, linearlyInterpolateDouble(one.saturation(), two.saturation(), balance), 255.0),
                            qBound(0.0, linearlyInterpolateDouble(one.value(), two.value(), balance), 255.0),
                            qBound(0.0, linearlyInterpolateDouble(one.alpha(), two.alpha(), balance), 255.0));
 
 }
 
 // Some private things for the adjust, change, and scale properties
 struct ParsedAdjustments {
     double red = 0.0;
     double green = 0.0;
     double blue = 0.0;
 
     double hue = 0.0;
     double saturation = 0.0;
     double value = 0.0;
 
     double alpha = 0.0;
 };
 
 ParsedAdjustments parseAdjustments(const QJSValue &value)
 {
     ParsedAdjustments parsed;
 
     auto checkProperty = [](const QJSValue &value, const QString &property) {
         if (value.hasProperty(property)) {
             auto val = value.property(property);
             if (val.isNumber()) {
                 return QVariant::fromValue(val.toNumber());
             }
         }
         return QVariant();
     };
 
     std::vector<std::pair<QString, double &>> items{{QStringLiteral("red"), parsed.red},
                                                     {QStringLiteral("green"), parsed.green},
                                                     {QStringLiteral("blue"), parsed.blue},
                                                     //
                                                     {QStringLiteral("hue"), parsed.hue},
                                                     {QStringLiteral("saturation"), parsed.saturation},
                                                     {QStringLiteral("value"), parsed.value},
                                                     {QStringLiteral("lightness"), parsed.value},
                                                     //
                                                     {QStringLiteral("alpha"), parsed.alpha}};
 
     for (const auto &item : items) {
         auto val = checkProperty(value, item.first);
         if (val.isValid()) {
             item.second = val.toDouble();
         }
     }
 
     if ((parsed.red || parsed.green || parsed.blue) && (parsed.hue || parsed.saturation || parsed.value)) {
         qCritical()  << "It is an error to have both RGB and HSL values in an adjustment.";
     }
 
     return parsed;
 }
 
 QColor ColorUtils::adjustColor(const QColor &color, const QJSValue &adjustments)
 {
     auto adjusts = parseAdjustments(adjustments);
 
     if (qBound(-360.0, adjusts.hue, 360.0) != adjusts.hue) {
         qCritical() << "Hue is out of bounds";
     }
     if (qBound(-255.0, adjusts.red, 255.0) != adjusts.red) {
         qCritical()  << "Red is out of bounds";
     }
     if (qBound(-255.0, adjusts.green, 255.0) != adjusts.green) {
         qCritical()  << "Green is out of bounds";
     }
     if (qBound(-255.0, adjusts.blue, 255.0) != adjusts.blue) {
         qCritical()  << "Green is out of bounds";
     }
     if (qBound(-255.0, adjusts.saturation, 255.0) != adjusts.saturation) {
         qCritical()  << "Saturation is out of bounds";
     }
     if (qBound(-255.0, adjusts.value, 255.0) != adjusts.value) {
         qCritical()  << "Value is out of bounds";
     }
     if (qBound(-255.0, adjusts.alpha, 255.0) != adjusts.alpha) {
         qCritical()  << "Alpha is out of bounds";
     }
 
     auto copy = color;
 
     if (adjusts.alpha) {
         copy.setAlpha(adjusts.alpha);
     }
 
     if (adjusts.red || adjusts.green || adjusts.blue) {
         copy.setRed(copy.red() + adjusts.red);
         copy.setGreen(copy.green() + adjusts.green);
         copy.setBlue(copy.blue() + adjusts.blue);
     } else if (adjusts.hue || adjusts.saturation || adjusts.value) {
         copy.setHsl(std::fmod(copy.hue() + adjusts.hue, 360.0), //
                     copy.saturation() + adjusts.saturation, //
                     copy.value() + adjusts.value,
                     copy.alpha());
     }
 
     return copy;
 }
 
 QColor ColorUtils::scaleColor(const QColor &color, const QJSValue &adjustments)
 {
     auto adjusts = parseAdjustments(adjustments);
     auto copy = color;
 
     if (qBound(-100.0, adjusts.red, 100.00) != adjusts.red) {
         qCritical()  << "Red is out of bounds";
     }
     if (qBound(-100.0, adjusts.green, 100.00) != adjusts.green) {
         qCritical()  << "Green is out of bounds";
     }
     if (qBound(-100.0, adjusts.blue, 100.00) != adjusts.blue) {
         qCritical()  << "Blue is out of bounds";
     }
     if (qBound(-100.0, adjusts.saturation, 100.00) != adjusts.saturation) {
         qCritical()  << "Saturation is out of bounds";
     }
     if (qBound(-100.0, adjusts.value, 100.00) != adjusts.value) {
         qCritical()  << "Value is out of bounds";
     }
     if (qBound(-100.0, adjusts.alpha, 100.00) != adjusts.alpha) {
         qCritical()  << "Alpha is out of bounds";
     }
 
     if (adjusts.hue != 0) {
         qCritical()  << "Hue cannot be scaled";
     }
 
     auto shiftToAverage = [](double current, double factor) {
         auto scale = qBound(-100.0, factor, 100.0) / 100;
         return current + (scale > 0 ? 255 - current : current) * scale;
     };
 
     if (adjusts.red || adjusts.green || adjusts.blue) {
         copy.setRed(qBound(0.0, shiftToAverage(copy.red(), adjusts.red), 255.0));
         copy.setGreen(qBound(0.0, shiftToAverage(copy.green(), adjusts.green), 255.0));
         copy.setBlue(qBound(0.0, shiftToAverage(copy.blue(), adjusts.blue), 255.0));
     } else {
         copy.setHsl(copy.hue(),
                     qBound(0.0, shiftToAverage(copy.saturation(), adjusts.saturation), 255.0),
                     qBound(0.0, shiftToAverage(copy.value(), adjusts.value), 255.0),
                     qBound(0.0, shiftToAverage(copy.alpha(), adjusts.alpha), 255.0));
     }
 
     return copy;
 }
 
 QColor ColorUtils::tintWithAlpha(const QColor &targetColor, const QColor &tintColor, double alpha)
 {
     qreal tintAlpha = tintColor.alphaF() * alpha;
     qreal inverseAlpha = 1.0 - tintAlpha;
 
     if (qFuzzyCompare(tintAlpha, 1.0)) {
         return tintColor;
     } else if (qFuzzyIsNull(tintAlpha)) {
         return targetColor;
     }
 
     return QColor::fromRgbF(tintColor.redF() * tintAlpha + targetColor.redF() * inverseAlpha,
                             tintColor.greenF() * tintAlpha + targetColor.greenF() * inverseAlpha,
                             tintColor.blueF() * tintAlpha + targetColor.blueF() * inverseAlpha,
                             tintAlpha + inverseAlpha * targetColor.alphaF());
 }
 
 ColorUtils::XYZColor ColorUtils::colorToXYZ(const QColor &color)
 {
     // http://wiki.nuaj.net/index.php/Color_Transforms#RGB_.E2.86.92_XYZ
     qreal r = color.redF();
     qreal g = color.greenF();
     qreal b = color.blueF();
     // Apply gamma correction (i.e. conversion to linear-space)
     auto correct = [](qreal &v) {
         if (v > 0.04045) {
             v = std::pow((v + 0.055) / 1.055, 2.4);
         } else {
             v = v / 12.92;
         }
     };
 
     correct(r);
     correct(g);
     correct(b);
 
     // Observer. = 2°, Illuminant = D65
     const qreal x = r * 0.4124 + g * 0.3576 + b * 0.1805;
     const qreal y = r * 0.2126 + g * 0.7152 + b * 0.0722;
     const qreal z = r * 0.0193 + g * 0.1192 + b * 0.9505;
 
     return XYZColor{x, y, z};
 }
 
 ColorUtils::LabColor ColorUtils::colorToLab(const QColor &color)
 {
     // First: convert to XYZ
     const auto xyz = colorToXYZ(color);
 
     // Second: convert from XYZ to L*a*b
     qreal x = xyz.x / 0.95047; // Observer= 2°, Illuminant= D65
     qreal y = xyz.y / 1.0;
     qreal z = xyz.z / 1.08883;
 
     auto pivot = [](qreal &v) {
         if (v > 0.008856) {
             v = std::pow(v, 1.0 / 3.0);
         } else {
             v = (7.787 * v) + (16.0 / 116.0);
         }
     };
 
     pivot(x);
     pivot(y);
     pivot(z);
 
     LabColor labColor;
     labColor.l = std::max(0.0, (116 * y) - 16);
     labColor.a = 500 * (x - y);
     labColor.b = 200 * (y - z);
 
     return labColor;
 }
 
 qreal ColorUtils::chroma(const QColor &color)
 {
     LabColor labColor = colorToLab(color);
 
     // Chroma is hypotenuse of a and b
     return sqrt(pow(labColor.a, 2) + pow(labColor.b, 2));
 }
 
 qreal ColorUtils::luminance(const QColor &color)
 {
     const auto &xyz = colorToXYZ(color);
     // Luminance is equal to Y
     return xyz.y;
 }
 
 #include "moc_colorutils.cpp"