Settings.hasTouchScreen returns false

Diracsbracket

Hi.
I am trying to find out why flicking is not working with a TreeView example on my Raspberry Pi3 with touch screen.

Looking at the qml code of TreeView.qml, e.g.
https://github.com/RSATom/Qt/blob/master/qtquickcontrols/src/controls/TreeView.qml:

BasicTableView {
...
    __mouseArea: MouseArea {
        id: mouseArea

        parent: __listView
        width: __listView.width
        height: __listView.height
        z: -1
        propagateComposedEvents: true
        focus: true
        // If there is not a touchscreen, keep the flickable from eating our mouse drags.
        // If there is a touchscreen, flicking is possible, but selection can be done only by tapping, not by dragging.
        preventStealing: !Settings.hasTouchScreen
        ...
     }
}

By similarly looking at the qml code for BasicTableView.qml, it seems that behavior is controlled by Settings.hasTouchScreen

According to:
https://code.woboq.org/qt5/qtquickcontrols/src/controls/Private/qquickcontrolsettings.cpp.html
it corresponds to the following method:

bool QQuickControlSettings1::hasTouchScreen() const
{
    const auto devices = QTouchDevice::devices();
    for (const QTouchDevice *dev : devices)
        if (dev->type() == QTouchDevice::TouchScreen)
            return true;
    return false;
}

However, in my case, Settings.hasTouchScreen returns false; i.e. the touch screen (although working for the rest), is not
correctly detected by the QML environment, which probably explains why the flicking does not work.

According to https://doc.qt.io/qt-5/qtouchdevice.html, my touch device should have been registered somehow by the private QWindowSystemInterface::registerTouchDevice() method, but wasn't.

How can I get this to work?
Thanks!

Diracsbracket

It seems things don't work correctly when using tslib as plugin?

In any case, when using the evdevtouch plugin instead
https://doc.qt.io/qt-5/embedded-linux.html

and adding the following test code in my main():

 //TEST TO SEE IF TOUCH DEVICE IS REGISTERED.
 const auto devices = QTouchDevice::devices();
 qDebug() << "************** devices.length(): " << devices.length();

 for (const QTouchDevice *dev : devices)
     qDebug() << "**************** dev->type():" << dev->type();

produced:

__logging_message__06:19:51.871 DEBUG unknown                          ************** devices.length():  1
__logging_message__06:19:51.872 DEBUG unknown                          **************** dev->type(): QTouchDevice::TouchScreen

And with the device now correctly reported, also the Settings.hasTouchScreen property in QML is correctly set and the flicking of the TreeView working.