Method drawScale

Gui/Histogram.cpp:1598–1698

}

void
HistogramPrivate::drawScale()
{
    // always running in the main thread
    assert( qApp && qApp->thread() == QThread::currentThread() );
    assert( QOpenGLContext::currentContext() == widget->context() );


    glCheckError();
    QPointF btmLeft = zoomCtx.toZoomCoordinates(0, widget->height() - 1);
    QPointF topRight = zoomCtx.toZoomCoordinates(widget->width() - 1, 0);

    ///don't attempt to draw a scale on a widget with an invalid height
    if (widget->height() <= 1) {
        return;
    }

    QFontMetrics fm(*_textFont);
    const double smallestTickSizePixel = 5.; // tick size (in pixels) for alpha = 0.
    const double largestTickSizePixel = 1000.; // tick size (in pixels) for alpha = 1.


    {
        GLProtectAttrib a(GL_COLOR_BUFFER_BIT | GL_CURRENT_BIT | GL_ENABLE_BIT);

        glEnable(GL_BLEND);
        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

        for (int axis = 0; axis < 2; ++axis) {
            const double rangePixel = (axis == 0) ? widget->width() : widget->height(); // AXIS-SPECIFIC
            const double range_min = (axis == 0) ? btmLeft.x() : btmLeft.y(); // AXIS-SPECIFIC
            const double range_max = (axis == 0) ? topRight.x() : topRight.y(); // AXIS-SPECIFIC
            const double range = range_max - range_min;
            double smallTickSize;
            bool half_tick;
            ticks_size(range_min, range_max, rangePixel, smallestTickSizePixel, &smallTickSize, &half_tick);
            int m1, m2;
            const int ticks_max = 1000;
            double offset;
            ticks_bounds(range_min, range_max, smallTickSize, half_tick, ticks_max, &offset, &m1, &m2);
            std::vector<int> ticks;
            ticks_fill(half_tick, ticks_max, m1, m2, &ticks);
            const double smallestTickSize = range * smallestTickSizePixel / rangePixel;
            const double largestTickSize = range * largestTickSizePixel / rangePixel;
#if QT_VERSION >= QT_VERSION_CHECK(5, 11, 0)
            const double minTickSizeTextPixel = ( (axis == 0) ? fm.horizontalAdvance( QLatin1String("00") ) : fm.height() ) / _screenPixelRatio;
#else
            const double minTickSizeTextPixel = ( (axis == 0) ? fm.width( QLatin1String("00") ) : fm.height() ) / _screenPixelRatio; // AXIS-SPECIFIC
#endif
            const double minTickSizeText = range * minTickSizeTextPixel / rangePixel;
            for (int i = m1; i <= m2; ++i) {
                double value = i * smallTickSize + offset;
                const double tickSize = ticks[i - m1] * smallTickSize;
                const double alpha = ticks_alpha(smallestTickSize, largestTickSize, tickSize);

                glColor4f(_baseAxisColor.redF(), _baseAxisColor.greenF(), _baseAxisColor.blueF(), alpha);

                glLineWidth(1. * _screenPixelRatio);