Unable to get touch events on QGraphicsView using single touch in Qt5.12.4

[Himanshu Rohilla]

Hi,

I create a sample application to get touch events from QGraphicsView using viewport events.

If I build this application with Qt5.6 then it is working and I can get Touch Begin, Touch Update and Touch End events. But when I compile it with Qt5.12.4, my application is not able to get Touch Update and Touch End events. It only gets Touch Begin.

This problem is only with single touch. If I use multi touch, then it works fine.

I share my sample application code.

#include "GraphicsView.h"

#include <QDebug>

CGraphicsView::CGraphicsView(Widget* wid)
{
    this->setParent(wid);

    this->setGeometry(wid->geometry());

    viewport()->setAttribute(Qt::WA_AcceptTouchEvents);
}

bool CGraphicsView::viewportEvent(QEvent *event)
{
    qDebug() << "event->type()" << event->type();

    switch (event->type()) {

    case QEvent::TouchBegin:
    {
        qDebug() << "In touch begin";
    }
        break;
    case QEvent::TouchUpdate:
    {
        qDebug() << "In touch update";
    }
        break;
    case QEvent::TouchEnd:
    {
        qDebug() << "In touch end";
    }
        break;
    default:
        break;
    }
    return QGraphicsView::viewportEvent(event);
}

In the above sample code, "wid" is an object of QWidget class and CGraphicsView class is inherited from QGraphicsView class.