QT eventFilter mouseEvent->pos().x() 始终为零但 mouseEvent->pos().y() 工作正常

Question

mouseEvent->pos().x() always return 0. mouseEvent->pos().y() updating on mouse move

bool Module3::eventFilter(QObject *obj, QEvent *event) { 

      QMouseEvent *mouseEvent = static_cast(event);

      if(obj ==scene && event->type() == QEvent::GraphicsSceneMouseMove){

          QToolTip::showText(mouseEvent->pos(),QString::number(mouseEvent->pos().x()) + 
           ", "  + QString::number( mouseEvent->pos().y()));
       }

       return false;
}

Answer 1

You have undefined behaviour. If event->type() is QEvent::GraphicsSceneMouseMove then the real type of event is QGraphicsSceneMouseEvent* not QMouseEvent* .

Try...

if (obj == scene && event->type() == QEvent::GraphicsSceneMouseMove) {
    if (auto *mouseEvent = dynamic_cast<QGraphicsSceneMouseEvent *>(event)) {
        QToolTip::showText(mouseEvent->scenePos().toPoint(),QString::number(mouseEvent->pos().x()) + 
            ", "  + QString::number( mouseEvent->pos().y()));
    }
}
return false;