qcoreapplication.cpp

奇趣公司比较新的qt/emd版本

    The event must be allocated on the heap since the post event queue
    will take ownership of the event and delete it once it has been posted.
    It is \e {not safe} to modify or delete the event after it has been posted.

    When control returns to the main event loop, all events that are
    stored in the queue will be sent using the notify() function.

    Events are processed in the order posted. For more control over the processing order,
    use the postEvent() overload below, which takes a priority argument. This function
    posts all event with a Qt::NormalEventPriority.

    \threadsafe

    \sa sendEvent(), notify(), sendPostedEvents()
*/

void QCoreApplication::postEvent(QObject *receiver, QEvent *event)
{
    postEvent(receiver, event, Qt::NormalEventPriority);
}


/*!
    \overload
    \since 4.3

    Adds the event \a event, with the object \a receiver as the receiver of the
    event, to an event queue and returns immediately.

    The event must be allocated on the heap since the post event queue
    will take ownership of the event and delete it once it has been posted.
    It is \e {not safe} to modify or delete the event after it has been posted.

    When control returns to the main event loop, all events that are
    stored in the queue will be sent using the notify() function.

    Events are sorted in descending \a priority order, i.e. events
    with a high \a priority are queued before events with a lower \a
    priority. The \a priority can be any integer value, i.e. between
    INT_MAX and INT_MIN, inclusive; see Qt::EventPriority for more
    details. Events with equal \a priority will be processed in the
    order posted.

    \threadsafe

    \sa sendEvent(), notify(), sendPostedEvents(), Qt::EventPriority
*/
void QCoreApplication::postEvent(QObject *receiver, QEvent *event, int priority)
{
    if (receiver == 0) {
        qWarning("QCoreApplication::postEvent: Unexpected null receiver");
        delete event;
        return;
    }

    QReadLocker locker(QObjectPrivate::readWriteLock());
    if (!QObjectPrivate::isValidObject(receiver)) {
        qWarning("QCoreApplication::postEvent: Receiver is not a valid QObject");
        delete event;
        return;
    }

    QThreadData *data = receiver->d_func()->threadData;
    if (!data) {
        // posting during destruction? just delete the event to prevent a leak
        delete event;
        return;
    }

    {
        QMutexLocker locker(&data->postEventList.mutex);

        // if this is one of the compressible events, do compression
        if (receiver->d_func()->postedEvents
            && self && self->compressEvent(event, receiver, &data->postEventList)) {
            return;
        }

        event->posted = true;
        ++receiver->d_func()->postedEvents;
        ++data->postEventList.numPostedEvents;
        if (event->type() == QEvent::DeferredDelete) {
            if (!data->eventLoops.isEmpty()) {
                // remember the current running eventloop
                for (int i = data->eventLoops.size() - 1; i >= 0; --i) {
                    QEventLoop *eventLoop = data->eventLoops.at(i);
                    if (eventLoop->isRunning()) {
                        event->d = reinterpret_cast<QEventPrivate *>(eventLoop);
                        break;
                    }
                }
            }
        }

        if (data->postEventList.isEmpty() || data->postEventList.last().priority >= priority) {
            // optimization: we can simply append if the last event in
            // the queue has higher or equal priority
            data->postEventList.append(QPostEvent(receiver, event, priority));
        } else {
            // insert event in descending priority order, using upper
            // bound for a given priority (to ensure proper ordering
            // of events with the same priority)
            QPostEventList::iterator begin = data->postEventList.begin() + data->postEventList.offset,
                                       end = data->postEventList.end();
            QPostEventList::iterator at = qUpperBound(begin, end, priority);
            data->postEventList.insert(at, QPostEvent(receiver, event, priority));
        }
        data->canWait = false;
    }

    if (data->eventDispatcher)
        data->eventDispatcher->wakeUp();
}

/*!
  \internal
  Returns true if \a event was compressed away (possibly deleted) and should not be added to the list.
*/
bool QCoreApplication::compressEvent(QEvent *event, QObject *receiver, QPostEventList *postedEvents)
{
#ifdef Q_WS_WIN
    Q_ASSERT(event);
    Q_ASSERT(receiver);
    Q_ASSERT(postedEvents);

    // compress posted timers to this object.
    if (event->type() == QEvent::Timer && receiver->d_func()->postedEvents > 0) {
        int timerId = ((QTimerEvent *) event)->timerId();
        for (int i=0; i<postedEvents->size(); ++i) {
            const QPostEvent &e = postedEvents->at(i);
            if (e.receiver == receiver && e.event && e.event->type() == QEvent::Timer
                && ((QTimerEvent *) e.event)->timerId() == timerId) {
                delete event;
                return true;
            }
        }
    } else
#endif
        if (event->type() == QEvent::DeferredDelete
            && receiver->d_func()->postedEvents > 0) {
            for (int i = 0; i < postedEvents->size(); ++i) {
                const QPostEvent &cur = postedEvents->at(i);
                if (cur.receiver != receiver || cur.event == 0 || cur.event->type() != event->type())
                    continue;
                // found a DeferredDelete for this receiver
                delete event;
                return true;
            }
        }
    return false;
}

/*!
  \fn void QCoreApplication::sendPostedEvents()
  \overload

    Dispatches all posted events, i.e. empties the event queue.
*/

/*!
  Immediately dispatches all events which have been previously queued
  with QCoreApplication::postEvent() and which are for the object \a receiver
  and have the event type \a event_type.

  Note that events from the window system are \e not dispatched by this
  function, but by processEvents().

  If \a receiver is null, the events of \a event_type are sent for all
  objects. If \a event_type is 0, all the events are sent for \a receiver.

  \sa flush(), postEvent()
*/

void QCoreApplication::sendPostedEvents(QObject *receiver, int event_type)
{
    QThreadData *data = QThreadData::current();

    QCoreApplicationPrivate::sendPostedEvents(receiver, event_type, data);
}

void QCoreApplicationPrivate::sendPostedEvents(QObject *receiver, int event_type,
                                               QThreadData *data)
{
    bool doDeferredDeletion = (event_type == QEvent::DeferredDelete);
    if (event_type == -1) {
        // we were called by the event dispatcher.
        doDeferredDeletion = true;
        event_type = 0;
    }


    if (receiver && receiver->d_func()->threadData != data) {
        qWarning("QCoreApplication::sendPostedEvents: Cannot send "
                 "posted events for objects in another thread");
        return;
    }

    ++data->postEventList.recursion;

#ifdef QT3_SUPPORT
    if (event_type == QEvent::ChildInserted) {
        if (receiver) {
            // optimize sendPostedEvents(w, QEvent::ChildInserted) calls away
            receiver->d_func()->sendPendingChildInsertedEvents();
            --data->postEventList.recursion;
            return;
        }

        // ChildInserted events are sent in response to *Request
        event_type = QEvent::ChildInsertedRequest;
    }
#endif

    QMutexLocker locker(&data->postEventList.mutex);

    // by default, we assume that the event dispatcher can go to sleep after
    // processing all events. if any new events are posted while we send
    // events, canWait will be set to false.
    data->canWait = (data->postEventList.size() == 0);

    if (data->postEventList.size() == 0 || (receiver && !receiver->d_func()->postedEvents)) {
        --data->postEventList.recursion;
        return;
    }

    data->canWait = true;

    // okay. here is the tricky loop. be careful about optimizing
    // this, it looks the way it does for good reasons.
    int i = 0;
    const int s = data->postEventList.size();
    const int savedOffset = data->postEventList.offset;
    data->postEventList.offset = s;
    while (i < data->postEventList.size()) {
        // avoid live-lock
        if (i >= s)
            break;

        const QPostEvent &pe = data->postEventList.at(i);
        ++i;

        if (!pe.event)
            continue;
        if ((receiver && receiver != pe.receiver) || (event_type && event_type != pe.event->type())) {
            data->canWait = false;
            continue;
        }

        if (pe.event->type() == QEvent::DeferredDelete) {
            QEventLoop *savedEventLoop = reinterpret_cast<QEventLoop *>(pe.event->d);
            QEventLoop *currentEventLoop = data->eventLoops.isEmpty() ? 0 : data->eventLoops.top();
            bool savedEventLoopIsRunning = data->eventLoops.contains(savedEventLoop);

            // DeferredDelete events are only sent when we are explicitly
            // asked to (s.a. QEventLoop::DeferredDeletion), and then only if
            // there is no current event loop, or if the current event loop is
            // equal to the loop in which deleteLater() was called.
            if (!doDeferredDeletion
                || (currentEventLoop
                    && savedEventLoop
                    && savedEventLoop != currentEventLoop
                    && savedEventLoopIsRunning)) {
                // cannot send deferred delete
                if (!event_type && !receiver) {
                    // don't lose the event
                    data->postEventList.append(pe);
                    const_cast<QPostEvent &>(pe).event = 0;
                }
                continue;
            }
        }

        // first, we diddle the event so that we can deliver
        // it, and that no one will try to touch it later.
        pe.event->posted = false;
        QEvent * e = pe.event;
        QObject * r = pe.receiver;

        --r->d_func()->postedEvents;
        --data->postEventList.numPostedEvents;
        Q_ASSERT(r->d_func()->postedEvents >= 0);

        // next, update the data structure so that we're ready
        // for the next event.
        const_cast<QPostEvent &>(pe).event = 0;

        locker.unlock();
        // after all that work, it's time to deliver the event.
#ifdef QT_NO_EXCEPTIONS
        QCoreApplication::sendEvent(r, e);
#else
        try {
            QCoreApplication::sendEvent(r, e);
        } catch (...) {
            delete e;
            locker.relock();

            // since we were interrupted, we need another pass to make sure we clean everything up
            data->canWait = false;

            // uglehack: copied from below
            data->postEventList.offset = savedOffset;
            --data->postEventList.recursion;
            if (!data->postEventList.recursion && !data->canWait && data->eventDispatcher)
                data->eventDispatcher->wakeUp();
            throw;              // rethrow
        }
#endif

        delete e;
        locker.relock();

        // careful when adding anything below this point - the
        // sendEvent() call might invalidate any invariants this
        // function depends on.
    }

    data->postEventList.offset = savedOffset;
    --data->postEventList.recursion;
    if (!data->postEventList.recursion && !data->canWait && data->eventDispatcher)
        data->eventDispatcher->wakeUp();

    // clear the global list, i.e. remove everything that was
    // delivered.
    if (!data->postEventList.recursion && !event_type && !receiver) {
        const QPostEventList::iterator it = data->postEventList.begin();
        data->postEventList.erase(it, it + i);
    }
}

/*!
  Removes all events posted using postEvent() for \a receiver.

  The events are \e not dispatched, instead they are removed from the
  queue. You should never need to call this function. If you do call it,
  be aware that killing events may cause \a receiver to break one or
  more invariants.

  \threadsafe
*/

void QCoreApplication::removePostedEvents(QObject *receiver)
{
    removePostedEvents(receiver, 0);
}

/*!
    \overload
    \since 4.3

    Removes all events of the given \a eventType that were posted
    using postEvent() for \a receiver.

    The events are \e not dispatched, instead they are removed from
    the queue. You should never need to call this function. If you do
    call it, be aware that killing events may cause \a receiver to
    break one or more invariants.

    If \a receiver is null, the events of \a eventType are removed for
    all objects. If \a eventType is 0, all the events are removed for
    \a receiver.

    \threadsafe
*/

void QCoreApplication::removePostedEvents(QObject *receiver, int eventType)
{
#ifdef QT3_SUPPORT
    if (eventType == QEvent::ChildInserted)
        eventType = QEvent::ChildInsertedRequest;
#endif

    QThreadData *data = receiver ? receiver->d_func()->threadData : QThreadData::current();
    QMutexLocker locker(&data->postEventList.mutex);

    // the QObject destructor calls this function directly.  this can
    // happen while the event loop is in the middle of posting events,
    // and when we get here, we may not have any more posted events
    // for this object.
    if (receiver && !receiver->d_func()->postedEvents)
        return;
    int n = data->postEventList.size();
    int j = 0;

    for (int i = 0; i < n; ++i) {
        const QPostEvent &pe = data->postEventList.at(i);

        if ((!receiver || pe.receiver == receiver)
            && (pe.event && (eventType == 0 || pe.event->type() == eventType))) {
            --pe.receiver->d_func()->postedEvents;
#ifdef QT3_SUPPORT
            if (pe.event->type() == QEvent::ChildInsertedRequest)
                pe.receiver->d_func()->removePendingChildInsertedEvents(0);
#endif
            pe.event->posted = false;
            delete pe.event;
            const_cast<QPostEvent &>(pe).event = 0;
        } else if (!data->postEventList.recursion) {
            if (i != j)
                data->postEventList.swap(i, j);
            ++j;
        }
    }

#ifdef QT_DEBUG
    if (receiver && eventType == 0) {
        Q_ASSERT(!receiver->d_func()->postedEvents);
    }
#endif