QString Conversion::contrastColor(const QString& color)
{
    if (color.isNull()) {
        return QColor(Qt::black).name();
    }

#if 0
    QColor color(bgColor);
    int d = 0;

    // counting the perceptive luminance - human eye favors green color...
    double a = 1 - (0.299 * color.red() + 0.587 * color.green() + 0.114 * color.blue()) / 255;

    if (a < 0.5) {
        d = 0; // bright colors - black font
    } else {
        d = 255; // dark colors - white font
    }
    return  QColor(d, d, d).name();
#else
    int luminosity = luma(QColor(color));
    if (luminosity <= 60) {
         return QColor(Qt::white).name();
    } else {
         return QColor(Qt::black).name();
    }
#endif
}