gistfile1.txt

void QGuiApplicationPrivate::processTabletEvent(QWindowSystemInterfacePrivate::TabletEvent *e)
{
#if QT_CONFIG(tabletevent)
    TabletPointData &pointData = tabletDevicePoint(e->uid);

    QEvent::Type type = QEvent::TabletMove;
    if (e->buttons != pointData.state)
        type = (e->buttons > pointData.state) ? QEvent::TabletPress : QEvent::TabletRelease;

    QPointF local = e->local;
    QWindow *window = e->window.data();
    modifier_buttons = e->modifiers;
    
    if (true) {
        window = QGuiApplication::topLevelAt(e->global.toPoint());
        QPointF delta = e->global - e->global.toPoint();
        local = window->mapFromGlobal(e->global.toPoint()) + delta;
    }

    // If window is null, pick one based on the global position and make sure all
    // subsequent events up to the release are delivered to that same window.
    // If window is given, just send to that.
    if (type == QEvent::TabletPress) {
        if (!window)
            return;
        pointData.target = window;
    } else {
        if (type == QEvent::TabletRelease)
            pointData.target = nullptr;
        if (!window)
            return;
    }
    
    Qt::MouseButtons stateChange = e->buttons ^ pointData.state;
    Qt::MouseButton button = Qt::NoButton;
    for (int check = Qt::LeftButton; check <= int(Qt::MaxMouseButton); check = check << 1) {
        if (check & stateChange) {
            button = Qt::MouseButton(check);
            break;
        }
    }
    QTabletEvent tabletEvent(type, local, e->global,
                             e->device, e->pointerType, e->pressure, e->xTilt, e->yTilt,
                             e->tangentialPressure, e->rotation, e->z,
                             e->modifiers, e->uid, button, e->buttons);
    tabletEvent.setAccepted(false);
    tabletEvent.setTimestamp(e->timestamp);
    QGuiApplication::sendSpontaneousEvent(window, &tabletEvent);
    pointData.state = e->buttons;
    if (!tabletEvent.isAccepted()
        && !QWindowSystemInterfacePrivate::TabletEvent::platformSynthesizesMouse
        && qApp->testAttribute(Qt::AA_SynthesizeMouseForUnhandledTabletEvents)) {

        const QEvent::Type mouseType = [&]() {
            switch (type) {
            case QEvent::TabletPress:   return QEvent::MouseButtonPress;
            case QEvent::TabletMove:    return QEvent::MouseMove;
            case QEvent::TabletRelease: return QEvent::MouseButtonRelease;
            default: Q_UNREACHABLE();
            }
        }();
        QWindowSystemInterfacePrivate::MouseEvent mouseEvent(window, e->timestamp, local,
            e->global, e->buttons, e->modifiers, button, mouseType, Qt::MouseEventSynthesizedByQt);
        mouseEvent.flags |= QWindowSystemInterfacePrivate::WindowSystemEvent::Synthetic;
        processMouseEvent(&mouseEvent);
    }
#else
    Q_UNUSED(e)
#endif
}