How to handle a release event for the second finger in QOpenGLWindow

[8Observer8]

I'm trying to create an Android game controller to make a Super Mario clone, just to learn programming and practice:

The next problem stopped me. I touch the screen with my first finger. While holding the first finger, I touch and release the second finger. I expect that when I release the second finger, the Qt Creator debug console should display:

TouchUpdate  2
TouchUpdate  1

void OpenGLWindow::touchEvent(QTouchEvent *event)
{
    switch (event->type())
    {
        case QEvent::TouchBegin:
        {
            qDebug() << "TouchBegin";
            event->accept();
            break;
        }
        case QEvent::TouchUpdate:
        {
            qDebug() << "TouchUpdate " << event->points().length();
            break;
        }
    }
}

But only the first few releases work normally. Then the releases work with delays. And after a few more releases I see:

TouchUpdate  2
TouchUpdate  2

Minimal example: release-event-of-the-second-finger-qt6-cpp.zip

Cross-ref: https://stackoverflow.com/questions/78096690/how-to-handle-a-release-event-for-the-second-finger-in-qopenglwindow

[8Observer8]

Solution: https://doc.qt.io/qt-6/qeventpoint.html#State-enum

void OpenGLWindow::touchEvent(QTouchEvent *event)
{
    switch (event->type())
    {
        case QEvent::TouchBegin:
        {
            qDebug() << "TouchBegin";
            event->accept();
            break;
        }
        case QEvent::TouchUpdate:
        {
            if (event->points().length() > 1)
            {
                QEventPoint::State firstState = event->points()[0].state();
                QEventPoint::State secondState = event->points()[1].state();
                if (firstState == QEventPoint::State::Released ||
                    secondState == QEventPoint::State::Released)
                {
                    qDebug() << "Released";
                }
            }
            break;
        }
    }
}