Rotary encoder

I would like the QDial of the rotary encoder not to move when clicked with the mouse but only when it is dragged.
There is a way to get this into a QDial.
Greetings

Maybe installing an event filter to catch the MousePressEvent and ignore it.

I tried like this:

Code:


bool KY040::eventFilter(QObject *object, QEvent *event)
{
    bool ret = false;
    if ( object == m_dial &&  ( event->type() == QEvent::MouseButtonPress )  ) {
        QMouseEvent* mouseEvent = static_cast<QMouseEvent*> (event);
        if(mouseEvent->buttons() == Qt::LeftButton) {
           //QStyleOptionSlider *opt = new QStyleOptionSlider;
           QStyleOptionComplex *opt = new QStyleOptionComplex;
           opt->initFrom(m_dial);
           QRect sr = m_dial->style()->subControlRect(QStyle::CC_Dial, opt, QStyle::SC_DialHandle, m_dial);
           qDebug() << sr;
           if (!sr.contains(mouseEvent->pos())){
              event->ignore();
              ret = true;
              qDebug() << "LEFT";
           }
        }
    }
    return ret;
}


The filter works but the rectangle of the indicator circle is empty, the method I copied from the code found on the internet for QSlider and QScrollBar.

Code:


    QStyleOptionSlider *opt = new QStyleOptionSlider;
    opt->initFrom(scrollBar1);
    
    QRect r = scrollBar1->style()->subControlRect(QStyle::CC_ScrollBar, opt, QStyle::SC_ScrollBarSubLine);


I tried to fit it to QDial but it gives an empty rectangle and I get this message:
"QCommonStyle::subControlRect: Case 6 not handled"

Greetings

Ignoring the press events is simple:

Code:

bool KY040::eventFilter( QObject *object, QEvent *event )
{
    bool ret = true;
    if( object == m_dial && event->type() == QEvent::MouseButtonPress )
    {
        QMouseEvent* mouseEvent = static_cast<QMouseEvent*> (event);
        if(mouseEvent->buttons() == Qt::LeftButton) ret = false;
    }
    return ret;
}

But this does not avoid the dial to move to mouse position (even ignoring the release event also).

The only solution I can think is reimplementing QDial and find out how to do by looking at QDial source code.
Maybe filtering Mouse move event and implementing something there could work as well.

I was unable to reimplement QDial but I did this:

Code:


bool KY040::eventFilter(QObject *object, QEvent *event)
{
    bool ret = false;
    int sliderpos = m_dial->sliderPosition();
    if (sliderpos == maximum) sliderpos = 0;
    if ( object == m_dial &&  ( event->type() == QEvent::MouseButtonPress )  ) {
        QMouseEvent* mouseEvent = static_cast<QMouseEvent*> (event);
        int frompoint = valueFromPoint(mouseEvent->pos());
        if (frompoint == maximum) frompoint = 0;
        if(mouseEvent->buttons() == Qt::LeftButton) {
          // qDebug() << valueFromPoint(mouseEvent->pos()) << m_dial->sliderPosition();
          if (sliderpos != frompoint) {
              event->ignore();
              ret = true;
          }
          else event->accept();
        }
    }
    return ret;
}

int KY040::valueFromPoint(const QPoint &p)
{
    double yy = m_dial->height()/2.0 - p.y();
    double xx = p.x() - m_dial->width()/2.0;
    double a = (xx || yy) ? std::atan2(yy, xx) : 0;
    if (a < (Q_PI / -2))
        a = a + Q_PI * 2;
    int dist = 0;
    int minv = minimum, maxv = maximum;
    if (minimum < 0) {
        dist = -minimum;
        minv = 0;
        maxv = maximum + dist;
    }
    int r = maxv - minv;
    int v;
    if (wrapping)
        v =  (int)(0.5 + minv + r * (Q_PI * 3 / 2 - a) / (2 * Q_PI));
    else
        v =  (int)(0.5 + minv + r* (Q_PI * 4 / 3 - a) / (Q_PI * 10 / 6));
    if (dist > 0)
        v -= dist;
    return !invertedAppearance ? bound(v) : maximum - bound(v);
}

int KY040::bound(int val)
{
    if (wrapping) {
        if ((val >= minimum) && (val <= maximum))
            return val;
        val = minimum + ((val - minimum) % (maximum - minimum));
        if (val < minimum)
            val += maximum - minimum;
        return val;
    } else {
        return qMax(minimum, qMin(maximum, val));
    }
}


Greetings

I was unable to reimplement QDial but I did this:

Nice, I will try it.