Qt 4.8. Tablet Events on Mac OS 10.6.8

Question

TabletEvents comes as mouse events.

Actual for MAC OS Qt 4.8.0 - 4.8.5. Works fine in Qt 4.7.3 on any OS and Qt 4.8.0 on Windows and Linux.

I have two instances of QGraphcisScene and two instances of QGraphicsView. The same types, but one view have a parent, and the another - doesn't (also it's transparent, used for drawing something over desktop).

I'm using tablet (wacom pen and touch) for painting. I handle QTabletEvents and it works only for QGrahicsView instance that doesn't have parent (means parent==0).

On the view with parent (

QMainWindow->centralWidget->ControlContainerWidget->QStackedLayout->QGraphicsView

) tablet events doesn't comes. They comes to QApplication::eventFilter fine, but doesn't comes to view. They comes to QMainWindow as mouseEvents. If i set parent to 0, tablet events delivers fine.

The 1st receiver of tablet event is QMainWindow. I see that inside qt_mac_handleTabletEvent:

QWidget *qwidget = [theView qt_qwidget];
QWidget *widgetToGetMouse = qwidget;

And then:

`qt_sendSpontaneousEvent(widgetToGetMouse, &qtabletEvent);`

qtabletEvent - is not accepted event created just before calling sendSpontaneousEvent.

Then inside QApplication::notify():

QWidget *w = static_cast<QWidget *>(receiver);
QTabletEvent *tablet = static_cast<QTabletEvent*>(e);
QPoint relpos = tablet->pos();
bool eventAccepted = tablet->isAccepted();
while (w) {
    QTabletEvent te(tablet->type(), relpos, tablet->globalPos(),
                    tablet->hiResGlobalPos(), tablet->device(), tablet->pointerType(),
                    tablet->pressure(), tablet->xTilt(), tablet->yTilt(),
                    tablet->tangentialPressure(), tablet->rotation(), tablet->z(),
                    tablet->modifiers(), tablet->uniqueId());
                    te.spont = e->spontaneous();
    res = d->notify_helper(w, w == receiver ? tablet : &te);
    eventAccepted = ((w == receiver) ? tablet : &te)->isAccepted();
    e->spont = false;
    if ((res && eventAccepted)
         || w->isWindow()
         || w->testAttribute(Qt::WA_NoMousePropagation))
        break;

    relpos += w->pos();
    w = w->parentWidget();
    }
    tablet->setAccepted(eventAccepted);

As we can see:

res = d->notify_helper(w, w == receiver ? tablet : &te);

It calls event processing by filters, layouts and then - QMainWindow::tabletEvent. Default implementation is event->ignore().

Since QMainWindow have no Parent, it is all. So tablet event doesn't comes to QMainWindow childs.

Then seems it is QWidget *qwidget = [theView qt_qwidget]; works wrong. Unfortunately, i can't debug it...

Please give me some hints... i'm stucked...

Answer 1

I spent more time on comparison Qt 4.8.0 and 4.7.3 and now i see that it is the problem in internal qt event dispatcher. It sends event to NSWindow (QMainWindow) instead of NSView (QGraphicsView). I didn't found where is the problem, but i found that QMainWindow returns false from ::event() method. So i reimplemented that method and parsed tablet event there:

bool UBMainWindow::event(QEvent *event)
{
    bool bRes = QMainWindow::event(event);

    if (NULL != UBApplication::boardController)
    {
        UBBoardView *controlV = UBApplication::boardController->controlView();
        if (controlV && controlV->isVisible())
        {
            switch (event->type())
            {
            case QEvent::TabletEnterProximity:
            case QEvent::TabletLeaveProximity:
            case QEvent::TabletMove:
            case QEvent::TabletPress:
            case QEvent::TabletRelease:
                {
                    return controlV->directTabletEvent(event);
                }
            }
        }
    }
    return bRes;
}

The problem is: i need to use tablet for any controls in application, so i need to determine when QGraphicsView is under mouse cursor:

bool UBBoardView::directTabletEvent(QEvent *event)
{
    QTabletEvent *tEvent = static_cast<QTabletEvent *>(event);
    tEvent = new QTabletEvent(tEvent->type()
        , mapFromGlobal(tEvent->pos())
        , tEvent->globalPos()
        , tEvent->hiResGlobalPos()
        , tEvent->device()
        , tEvent->pointerType()
        , tEvent->pressure()
        , tEvent->xTilt()
        , tEvent->yTilt()
        , tEvent->tangentialPressure()
        , tEvent->rotation()
        , tEvent->z()
        , tEvent->modifiers()
        , tEvent->uniqueId());

    if (geometry().contains(tEvent->pos()))
    {
        if (NULL == widgetForTabletEvent(this->parentWidget(), tEvent->pos()))
        {
            tabletEvent(tEvent);
            return true;
        }
    }
    return false;
}

Also i need to stop handle tablet events for QGraphicsView childs.

QWidget *UBBoardView::widgetForTabletEvent(QWidget *w, const QPoint &pos)
{
    Q_ASSERT(w);


    UBBoardView *board = qobject_cast<UBBoardView *>(w);

    QWidget *childAtPos = NULL;

    QList<QObject *> childs = w->children();
    foreach(QObject *child, childs)
    {
        QWidget *childWidget = qobject_cast<QWidget *>(child);
        if (childWidget)
        {
            if (childWidget->isVisible() && childWidget->geometry().contains(pos))
            {
                QWidget *lastChild = widgetForTabletEvent(childWidget, pos);

                if (board && board->viewport() == lastChild)
                    continue;

                if (NULL != lastChild)
                    childAtPos = lastChild;
                else
                    childAtPos = childWidget;

                break;
            }
            else
                childAtPos = NULL;
        }
    }
    return childAtPos;
}

Maybe when i will have more time - i will investigate qt more deeply and fix that problem at all.