qobject.cpp

奇趣公司比较新的qt/emd版本

    Example:
    \code
        class MainWindow : public QMainWindow
        {
        public:
            MainWindow();

        protected:
            bool eventFilter(QObject *obj, QEvent *ev);

        private:
            QTextEdit *textEdit;
        };

        MainWindow::MainWindow()
        {
            textEdit = new QTextEdit;
            setCentralWidget(textEdit);

            textEdit->installEventFilter(this);
        }

        bool MainWindow::eventFilter(QObject *obj, QEvent *event)
        {
            if (obj == textEdit) {
                if (event->type() == QEvent::KeyPress) {
                    QKeyEvent *keyEvent = static_cast<QKeyEvent*>(event);
                    qDebug() << "Ate key press" << keyEvent->key();
                    return true;
                } else {
                    return false;
                }
            } else {
                // pass the event on to the parent class
                return QMainWindow::eventFilter(obj, event);
            }
        }
    \endcode

    Notice in the example above that unhandled events are passed to
    the base class's eventFilter() function, since the base class
    might have reimplemented eventFilter() for its own internal
    purposes.

    \warning If you delete the receiver object in this function, be
    sure to return true. Otherwise, Qt will forward the event to the
    deleted object and the program might crash.

    \sa installEventFilter()
*/

bool QObject::eventFilter(QObject * /* watched */, QEvent * /* event */)
{
    return false;
}

/*!
    \fn bool QObject::signalsBlocked() const

    Returns true if signals are blocked; otherwise returns false.

    Signals are not blocked by default.

    \sa blockSignals()
*/

/*!
    If \a block is true, signals emitted by this object are blocked
    (i.e., emitted signals disappear into hyperspace). If \a block is
    false, no such blocking will occur.

    The return value is the previous value of signalsBlocked().

    Note that the destroyed() signal will be emitted even if the signals
    for this object have been blocked.

    \sa signalsBlocked()
*/

bool QObject::blockSignals(bool block)
{
    Q_D(QObject);
    bool previous = d->blockSig;
    d->blockSig = block;
    return previous;
}

/*!
    Returns the thread in which the object lives.

    \sa moveToThread()
*/
QThread *QObject::thread() const
{
    return d_func()->threadData->thread;
}

/*!
    Changes the thread affinity for this object and its children. The
    object cannot be moved if it has a parent. Event processing will
    continue in the \a targetThread.

    To move an object to the main thread, use QApplication::instance()
    to retrieve a pointer to the current application, and then use
    QApplication::thread() to retrieve the thread in which the
    application lives. For example:

    \code
        myObject->moveToThread(QApplication::instance()->thread());
    \endcode

    If \a targetThread is zero, all event processing for this object
    and its children stops.

    Note that all active timers for the object will be reset. The
    timers are first stopped in the current thread and restarted (with
    the same interval) in the \a targetThread. As a result, constantly
    moving an object between threads can postpone timer events
    indefinitely.

    A QEvent::ThreadChange event is sent to this object just before
    the thread affinity is changed. You can handle this event to
    perform any special processing. Note that any new events that are
    posted to this object will be handled in the \a targetThread.

    \warning This function is \e not thread-safe; the current thread
    must be same as the current thread affinity. In other words, this
    function can only "push" an object from the current thread to
    another thread, it cannot "pull" an object from any arbitrary
    thread to the current thread.

    \sa thread()
 */
void QObject::moveToThread(QThread *targetThread)
{
    Q_D(QObject);

    if (d->threadData->thread == targetThread) {
        // object is already in this thread
        return;
    }

    if (d->parent != 0) {
        qWarning("QObject::moveToThread: Cannot move objects with a parent");
        return;
    }
    if (d->isWidget) {
        qWarning("QObject::moveToThread: Widgets cannot be moved to a new thread");
        return;
    }

    QThreadData *currentData = QThreadData::current();
    QThreadData *targetData = targetThread ? QThreadData::get2(targetThread) : new QThreadData(0);
    if (d->threadData->thread == 0 && currentData == targetData) {
        // one exception to the rule: we allow moving objects with no thread affinity to the current thread
        currentData = d->threadData;
    } else if (d->threadData != currentData) {
        qWarning("QObject::moveToThread: Current thread (%p) is not the object's thread (%p).\n"
                 "Cannot move to target thread (%p)\n",
                 d->threadData->thread, currentData->thread, targetData->thread);
        return;
    }

    // prepare to move
    d->moveToThread_helper();

    QWriteLocker locker(QObjectPrivate::readWriteLock());
    if (currentData != targetData) {
        targetData->postEventList.mutex.lock();
        while (currentData && !currentData->postEventList.mutex.tryLock()) {
            targetData->postEventList.mutex.unlock();
            targetData->postEventList.mutex.lock();
        }
    }

    // keep currentData alive (since we've got it locked)
    currentData->ref();

    // move the object
    d_func()->setThreadData_helper(currentData, targetData);

    if (currentData != targetData) {
        targetData->postEventList.mutex.unlock();
        if (currentData)
            currentData->postEventList.mutex.unlock();
    }

    // now currentData can commit suicide if it wants to
    currentData->deref();
}

void QObjectPrivate::moveToThread_helper()
{
    Q_Q(QObject);
    QEvent e(QEvent::ThreadChange);
    QCoreApplication::sendEvent(q, &e);
    for (int i = 0; i < children.size(); ++i) {
        QObject *child = children.at(i);
        child->d_func()->moveToThread_helper();
    }
}

void QObjectPrivate::setThreadData_helper(QThreadData *currentData, QThreadData *targetData)
{
    Q_Q(QObject);

    // move posted events
    int eventsMoved = 0;
    for (int i = 0; i < currentData->postEventList.size(); ++i) {
        const QPostEvent &pe = currentData->postEventList.at(i);
        if (!pe.event)
            continue;
        if (pe.receiver == q) {
            // move this post event to the targetList
            targetData->postEventList.append(pe);
            const_cast<QPostEvent &>(pe).event = 0;
            ++eventsMoved;
        }
    }
    if (eventsMoved > 0 && targetData->eventDispatcher)
        targetData->eventDispatcher->wakeUp();

    // set new thread data
    targetData->ref();
    threadData->deref();
    threadData = targetData;

    for (int i = 0; i < children.size(); ++i) {
        QObject *child = children.at(i);
        child->d_func()->setThreadData_helper(currentData, targetData);
    }
}

void QObjectPrivate::_q_reregisterTimers(void *pointer)
{
    Q_Q(QObject);
    QList<QPair<int, int> > *timerList = reinterpret_cast<QList<QPair<int, int> > *>(pointer);
    QAbstractEventDispatcher *eventDispatcher = threadData->eventDispatcher;
    for (int i = 0; i < timerList->size(); ++i) {
        const QPair<int, int> &pair = timerList->at(i);
        eventDispatcher->registerTimer(pair.first, pair.second, q);
    }
    delete timerList;
}


//
// The timer flag hasTimer is set when startTimer is called.
// It is not reset when killing the timer because more than
// one timer might be active.
//

/*!
    Starts a timer and returns a timer identifier, or returns zero if
    it could not start a timer.

    A timer event will occur every \a interval milliseconds until
    killTimer() is called. If \a interval is 0, then the timer event
    occurs once every time there are no more window system events to
    process.

    The virtual timerEvent() function is called with the QTimerEvent
    event parameter class when a timer event occurs. Reimplement this
    function to get timer events.

    If multiple timers are running, the QTimerEvent::timerId() can be
    used to find out which timer was activated.

    Example:

    \code
        class MyObject : public QObject
        {
            Q_OBJECT

        public:
            MyObject(QObject *parent = 0);

        protected:
            void timerEvent(QTimerEvent *event);
        };

        MyObject::MyObject(QObject *parent)
            : QObject(parent)
        {
            startTimer(50);     // 50-millisecond timer
            startTimer(1000);   // 1-second timer
            startTimer(60000);  // 1-minute timer
        }

        void MyObject::timerEvent(QTimerEvent *event)
        {
            qDebug() << "Timer ID:" << event->timerId();
        }
    \endcode

    Note that QTimer's accuracy depends on the underlying operating
    system and hardware. Most platforms support an accuracy of 20
    milliseconds; some provide more. If Qt is unable to deliver the
    requested number of timer events, it will silently discard some.

    The QTimer class provides a high-level programming interface with
    single-shot timers and timer signals instead of events. There is
    also a QBasicTimer class that is more lightweight than QTimer and
    less clumsy than using timer IDs directly.

    \sa timerEvent(), killTimer(), QTimer::singleShot()
*/

int QObject::startTimer(int interval)
{
    Q_D(QObject);

    if (interval < 0) {
        qWarning("QObject::startTimer: QTimer cannot have a negative interval");
        return 0;
    }

    d->pendTimer = true;                                // set timer flag

    if (!d->threadData->eventDispatcher) {
        qWarning("QObject::startTimer: QTimer can only be used with threads started with QThread");
        return 0;
    }
    return d->threadData->eventDispatcher->registerTimer(interval, this);
}

/*!
    Kills the timer with timer identifier, \a id.

    The timer identifier is returned by startTimer() when a timer
    event is started.

    \sa timerEvent(), startTimer()
*/

void QObject::killTimer(int id)
{
    Q_D(QObject);
    if (d->threadData->eventDispatcher)
        d->threadData->eventDispatcher->unregisterTimer(id);
}


/*!
    \fn QObject *QObject::parent() const

    Returns a pointer to the parent object.

    \sa children()
*/

/*!
    \fn const QObjectList &QObject::children() const

    Returns a list of child objects.
    The QObjectList class is defined in the \c{<QObject>} header
    file as the following:

    \quotefromfile src/corelib/kernel/qobject.h
    \skipto /typedef .*QObjectList/
    \printuntil QObjectList

    The first child added is the \l{QList::first()}{first} object in
    the list and the last child added is the \l{QList::last()}{last}
    object in the list, i.e. new children are appended at the end.

    Note that the list order changes when QWidget children are
    \l{QWidget::raise()}{raised} or \l{QWidget::lower()}{lowered}. A
    widget that is raised becomes the last object in the list, and a
    widget that is lowered becomes the first object in the list.

    \sa findChild(), findChildren(), parent(), setParent()
*/

#ifdef QT3_SUPPORT
static void objSearch(QObjectList &result,
                       const QObjectList &list,
                       const char  *inheritsClass,
                       bool onlyWidgets,
                       const char  *objName,
                       QRegExp           *rx,
                       bool            recurse)
{
    for (int i = 0; i < list.size(); ++i) {
        QObject *obj = list.at(i);
        bool ok = true;
        if (onlyWidgets)
            ok = obj->isWidgetType();
        else if (inheritsClass && !obj->inherits(inheritsClass))
            ok = false;
        if (ok) {
            if (objName)
                ok = (obj->objectName() == QLatin1String(objName));
#ifndef QT_NO_REGEXP
            else if (rx)
                ok = (rx->indexIn(obj->objectName()) != -1);
#endif
        }
        if (ok)                                // match!
            result.append(obj);
        if (recurse) {
            QObjectList clist = obj->children();
            if (!clist.isEmpty())
                objSearch(result, clist, inheritsClass,
                           onlyWidgets, objName, rx, recurse);
        }
    }
}

/*!
    \internal

    Searches the children and optionally grandchildren of this object,