Qt 5.5 - 触控/多点触控无法与Ubuntu 14.04配合使用

Question

I am trying to create a Qt Widgets application that supports multitouch. I am using a tablet with Ubuntu 14.04, QtCreator 3.5.0 and Qt 5.5.0 installed. I am compiling straight on the tablet.

I tried compiling some of the Qt Quick and Qt Widgets examples like this , this and this one . All of them compiled well and all of them supported mouse and single-touch events but none supported multi-touch.

I tried modifying the source code of the last of the examples like this:

bool ImageWidget::event(QEvent *event)
{
    std::cout << GetEvent(event).toStdString() << std::endl;
    if (event->type() == QEvent::Gesture)
        return gestureEvent(static_cast<QGestureEvent*>(event));
    return QWidget::event(event);
}

QString ImageWidget::GetEvent(const QEvent * ev) {
   static int eventEnumIndex = QEvent::staticMetaObject
         .indexOfEnumerator("Type");
   QString result;
   result.append("QEvent");
   if (ev) {
      QString name = QEvent::staticMetaObject
            .enumerator(eventEnumIndex).valueToKey(ev->type());
      if (!name.isEmpty()) result.append(name); else result.append(ev->type());
   } else {
      result.append( "foo");
   }
   return result;
}

And all the output I get when I try to touch drag an item are sort of mouse events:

QEventMouseButtonPress
QEventMouseMove
QEventMouseMove
QEventMouseMove
QEventMouseMove
QEventMouseMove
QEventMouseMove
QEventMouseButtonRelease
QEventLeave

Other applications (like Google Chrome or Ubuntu itself) handle multitouch fine, so I guess it has something to do with Qt.

XInput states this about the currently installed versions:

xinput version 1.6.1
XI version on server: 2.3

I am relatively new to Qt and Ubuntu in general, so the problem could actually be pretty simple, but googling gave me no results. Thanks for your help in advance.

UPDATE

Also, I'd appreciate if someone shared the experience of using touch with Qt on Ubuntu or other Linux-based distros so that I could figure out whether it is a bug in OS or has something to do with hardware.

Answer 1

To implement multi touch on single widget , we need to different events rather than QEventMouseButtonPress etc. There are new events types like TouchBegin , TouchUpdate , TouchEnd and new TouchEventsClass.

For better understanding follow link http://www.slideshare.net/qtbynokia/using-multitouch-and-gestures-with-qt