/**************************************************************************** ** ** Copyright (C) 2016 The Qt Company Ltd. ** Copyright (C) 2016 Intel Corporation. ** Contact: https://www.qt.io/licensing/ ** ** This file is part of the QtCore module of the Qt Toolkit. ** ** $QT_BEGIN_LICENSE:LGPL$ ** Commercial License Usage ** Licensees holding valid commercial Qt licenses may use this file in ** accordance with the commercial license agreement provided with the ** Software or, alternatively, in accordance with the terms contained in ** a written agreement between you and The Qt Company. For licensing terms ** and conditions see https://www.qt.io/terms-conditions. For further ** information use the contact form at https://www.qt.io/contact-us. ** ** GNU Lesser General Public License Usage ** Alternatively, this file may be used under the terms of the GNU Lesser ** General Public License version 3 as published by the Free Software ** Foundation and appearing in the file LICENSE.LGPL3 included in the ** packaging of this file. Please review the following information to ** ensure the GNU Lesser General Public License version 3 requirements ** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. ** ** GNU General Public License Usage ** Alternatively, this file may be used under the terms of the GNU ** General Public License version 2.0 or (at your option) the GNU General ** Public license version 3 or any later version approved by the KDE Free ** Qt Foundation. The licenses are as published by the Free Software ** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 ** included in the packaging of this file. Please review the following ** information to ensure the GNU General Public License requirements will ** be met: https://www.gnu.org/licenses/gpl-2.0.html and ** https://www.gnu.org/licenses/gpl-3.0.html. ** ** $QT_END_LICENSE$ ** ****************************************************************************/ #include "qtimer.h" #include "qabstracteventdispatcher.h" #include "qcoreapplication.h" #include "qobject_p.h" QT_BEGIN_NAMESPACE /*! \class QTimer \inmodule QtCore \brief The QTimer class provides repetitive and single-shot timers. \ingroup events The QTimer class provides a high-level programming interface for timers. To use it, create a QTimer, connect its timeout() signal to the appropriate slots, and call start(). From then on, it will emit the timeout() signal at constant intervals. Example for a one second (1000 millisecond) timer (from the \l{widgets/analogclock}{Analog Clock} example): \snippet ../widgets/widgets/analogclock/analogclock.cpp 4 \snippet ../widgets/widgets/analogclock/analogclock.cpp 5 \snippet ../widgets/widgets/analogclock/analogclock.cpp 6 From then on, the \c update() slot is called every second. You can set a timer to time out only once by calling setSingleShot(true). You can also use the static QTimer::singleShot() function to call a slot after a specified interval: \snippet timers/timers.cpp 3 In multithreaded applications, you can use QTimer in any thread that has an event loop. To start an event loop from a non-GUI thread, use QThread::exec(). Qt uses the timer's \l{QObject::thread()}{thread affinity} to determine which thread will emit the \l{QTimer::}{timeout()} signal. Because of this, you must start and stop the timer in its thread; it is not possible to start a timer from another thread. As a special case, a QTimer with a timeout of 0 will time out as soon as all the events in the window system's event queue have been processed. This can be used to do heavy work while providing a snappy user interface: \snippet timers/timers.cpp 4 \snippet timers/timers.cpp 5 \snippet timers/timers.cpp 6 From then on, \c processOneThing() will be called repeatedly. It should be written in such a way that it always returns quickly (typically after processing one data item) so that Qt can deliver events to the user interface and stop the timer as soon as it has done all its work. This is the traditional way of implementing heavy work in GUI applications, but as multithreading is nowadays becoming available on more and more platforms, we expect that zero-millisecond QTimer objects will gradually be replaced by \l{QThread}s. \section1 Accuracy and Timer Resolution The accuracy of timers depends on the underlying operating system and hardware. Most platforms support a resolution of 1 millisecond, though the accuracy of the timer will not equal this resolution in many real-world situations. The accuracy also depends on the \l{Qt::TimerType}{timer type}. For Qt::PreciseTimer, QTimer will try to keep the accurance at 1 millisecond. Precise timers will also never time out earlier than expected. For Qt::CoarseTimer and Qt::VeryCoarseTimer types, QTimer may wake up earlier than expected, within the margins for those types: 5% of the interval for Qt::CoarseTimer and 500 ms for Qt::VeryCoarseTimer. All timer types may time out later than expected if the system is busy or unable to provide the requested accuracy. In such a case of timeout overrun, Qt will emit activated() only once, even if multiple timeouts have expired, and then will resume the original interval. \section1 Alternatives to QTimer An alternative to using QTimer is to call QObject::startTimer() for your object and reimplement the QObject::timerEvent() event handler in your class (which must inherit QObject). The disadvantage is that timerEvent() does not support such high-level features as single-shot timers or signals. Another alternative is QBasicTimer. It is typically less cumbersome than using QObject::startTimer() directly. See \l{Timers} for an overview of all three approaches. Some operating systems limit the number of timers that may be used; Qt tries to work around these limitations. \sa QBasicTimer, QTimerEvent, QObject::timerEvent(), Timers, {Analog Clock Example}, {Wiggly Example} */ static const int INV_TIMER = -1; // invalid timer id /*! Constructs a timer with the given \a parent. */ QTimer::QTimer(QObject *parent) : QObject(parent), id(INV_TIMER), inter(0), del(0), single(0), nulltimer(0), type(Qt::CoarseTimer) { Q_UNUSED(del); // ### Qt 6: remove field } /*! Destroys the timer. */ QTimer::~QTimer() { if (id != INV_TIMER) // stop running timer stop(); } /*! \fn void QTimer::timeout() This signal is emitted when the timer times out. \sa interval, start(), stop() */ /*! \property QTimer::active \since 4.3 This boolean property is \c true if the timer is running; otherwise false. */ /*! \fn bool QTimer::isActive() const Returns \c true if the timer is running (pending); otherwise returns false. */ /*! \fn int QTimer::timerId() const Returns the ID of the timer if the timer is running; otherwise returns -1. */ /*! \overload start() Starts or restarts the timer with the timeout specified in \l interval. If the timer is already running, it will be \l{QTimer::stop()}{stopped} and restarted. If \l singleShot is true, the timer will be activated only once. */ void QTimer::start() { if (id != INV_TIMER) // stop running timer stop(); nulltimer = (!inter && single); id = QObject::startTimer(inter, Qt::TimerType(type)); } /*! Starts or restarts the timer with a timeout interval of \a msec milliseconds. If the timer is already running, it will be \l{QTimer::stop()}{stopped} and restarted. If \l singleShot is true, the timer will be activated only once. */ void QTimer::start(int msec) { inter = msec; start(); } /*! Stops the timer. \sa start() */ void QTimer::stop() { if (id != INV_TIMER) { QObject::killTimer(id); id = INV_TIMER; } } /*! \reimp */ void QTimer::timerEvent(QTimerEvent *e) { if (e->timerId() == id) { if (single) stop(); emit timeout(QPrivateSignal()); } } class QSingleShotTimer : public QObject { Q_OBJECT int timerId; bool hasValidReceiver; QPointer receiver; QtPrivate::QSlotObjectBase *slotObj; public: ~QSingleShotTimer(); QSingleShotTimer(int msec, Qt::TimerType timerType, const QObject *r, const char * m); QSingleShotTimer(int msec, Qt::TimerType timerType, const QObject *r, QtPrivate::QSlotObjectBase *slotObj); Q_SIGNALS: void timeout(); protected: void timerEvent(QTimerEvent *) Q_DECL_OVERRIDE; }; QSingleShotTimer::QSingleShotTimer(int msec, Qt::TimerType timerType, const QObject *r, const char *member) : QObject(QAbstractEventDispatcher::instance()), hasValidReceiver(true), slotObj(0) { timerId = startTimer(msec, timerType); connect(this, SIGNAL(timeout()), r, member); } QSingleShotTimer::QSingleShotTimer(int msec, Qt::TimerType timerType, const QObject *r, QtPrivate::QSlotObjectBase *slotObj) : QObject(QAbstractEventDispatcher::instance()), hasValidReceiver(r), receiver(r), slotObj(slotObj) { timerId = startTimer(msec, timerType); if (r && thread() != r->thread()) { // Avoid leaking the QSingleShotTimer instance in case the application exits before the timer fires connect(QCoreApplication::instance(), &QCoreApplication::aboutToQuit, this, &QObject::deleteLater); setParent(0); moveToThread(r->thread()); } } QSingleShotTimer::~QSingleShotTimer() { if (timerId > 0) killTimer(timerId); if (slotObj) slotObj->destroyIfLastRef(); } void QSingleShotTimer::timerEvent(QTimerEvent *) { // need to kill the timer _before_ we emit timeout() in case the // slot connected to timeout calls processEvents() if (timerId > 0) killTimer(timerId); timerId = -1; if (slotObj) { // If the receiver was destroyed, skip this part if (Q_LIKELY(!receiver.isNull() || !hasValidReceiver)) { // We allocate only the return type - we previously checked the function had // no arguments. void *args[1] = { 0 }; slotObj->call(const_cast(receiver.data()), args); } } else { emit timeout(); } // we would like to use delete later here, but it feels like a // waste to post a new event to handle this event, so we just unset the flag // and explicitly delete... qDeleteInEventHandler(this); } /*! \internal Implementation of the template version of singleShot \a msec is the timer interval \a timerType is the timer type \a receiver is the receiver object, can be null. In such a case, it will be the same as the final sender class. \a slot a pointer only used when using Qt::UniqueConnection \a slotObj the slot object */ void QTimer::singleShotImpl(int msec, Qt::TimerType timerType, const QObject *receiver, QtPrivate::QSlotObjectBase *slotObj) { new QSingleShotTimer(msec, timerType, receiver, slotObj); } /*! \reentrant This static function calls a slot after a given time interval. It is very convenient to use this function because you do not need to bother with a \l{QObject::timerEvent()}{timerEvent} or create a local QTimer object. Example: \snippet code/src_corelib_kernel_qtimer.cpp 0 This sample program automatically terminates after 10 minutes (600,000 milliseconds). The \a receiver is the receiving object and the \a member is the slot. The time interval is \a msec milliseconds. \sa start() */ void QTimer::singleShot(int msec, const QObject *receiver, const char *member) { // coarse timers are worst in their first firing // so we prefer a high precision timer for something that happens only once // unless the timeout is too big, in which case we go for coarse anyway singleShot(msec, msec >= 2000 ? Qt::CoarseTimer : Qt::PreciseTimer, receiver, member); } /*! \overload \reentrant This static function calls a slot after a given time interval. It is very convenient to use this function because you do not need to bother with a \l{QObject::timerEvent()}{timerEvent} or create a local QTimer object. The \a receiver is the receiving object and the \a member is the slot. The time interval is \a msec milliseconds. The \a timerType affects the accuracy of the timer. \sa start() */ void QTimer::singleShot(int msec, Qt::TimerType timerType, const QObject *receiver, const char *member) { if (Q_UNLIKELY(msec < 0)) { qWarning("QTimer::singleShot: Timers cannot have negative timeouts"); return; } if (receiver && member) { if (msec == 0) { // special code shortpath for 0-timers const char* bracketPosition = strchr(member, '('); if (!bracketPosition || !(member[0] >= '0' && member[0] <= '2')) { qWarning("QTimer::singleShot: Invalid slot specification"); return; } QByteArray methodName(member+1, bracketPosition - 1 - member); // extract method name QMetaObject::invokeMethod(const_cast(receiver), methodName.constData(), Qt::QueuedConnection); return; } (void) new QSingleShotTimer(msec, timerType, receiver, member); } } /*!\fn void QTimer::singleShot(int msec, const QObject *receiver, PointerToMemberFunction method) \since 5.4 \overload \reentrant This static function calls a member function of a QObject after a given time interval. It is very convenient to use this function because you do not need to bother with a \l{QObject::timerEvent()}{timerEvent} or create a local QTimer object. The \a receiver is the receiving object and the \a method is the member function. The time interval is \a msec milliseconds. If \a receiver is destroyed before the interval occurs, the method will not be called. The function will be run in the thread of \a receiver. The receiver's thread must have a running Qt event loop. \sa start() */ /*!\fn void QTimer::singleShot(int msec, Qt::TimerType timerType, const QObject *receiver, PointerToMemberFunction method) \since 5.4 \overload \reentrant This static function calls a member function of a QObject after a given time interval. It is very convenient to use this function because you do not need to bother with a \l{QObject::timerEvent()}{timerEvent} or create a local QTimer object. The \a receiver is the receiving object and the \a method is the member function. The time interval is \a msec milliseconds. The \a timerType affects the accuracy of the timer. If \a receiver is destroyed before the interval occurs, the method will not be called. The function will be run in the thread of \a receiver. The receiver's thread must have a running Qt event loop. \sa start() */ /*!\fn void QTimer::singleShot(int msec, Functor functor) \since 5.4 \overload \reentrant This static function calls \a functor after a given time interval. It is very convenient to use this function because you do not need to bother with a \l{QObject::timerEvent()}{timerEvent} or create a local QTimer object. The time interval is \a msec milliseconds. \sa start() */ /*!\fn void QTimer::singleShot(int msec, Qt::TimerType timerType, Functor functor) \since 5.4 \overload \reentrant This static function calls \a functor after a given time interval. It is very convenient to use this function because you do not need to bother with a \l{QObject::timerEvent()}{timerEvent} or create a local QTimer object. The time interval is \a msec milliseconds. The \a timerType affects the accuracy of the timer. \sa start() */ /*!\fn void QTimer::singleShot(int msec, const QObject *context, Functor functor) \since 5.4 \overload \reentrant This static function calls \a functor after a given time interval. It is very convenient to use this function because you do not need to bother with a \l{QObject::timerEvent()}{timerEvent} or create a local QTimer object. The time interval is \a msec milliseconds. If \a context is destroyed before the interval occurs, the method will not be called. The function will be run in the thread of \a context. The context's thread must have a running Qt event loop. \sa start() */ /*!\fn void QTimer::singleShot(int msec, Qt::TimerType timerType, const QObject *context, Functor functor) \since 5.4 \overload \reentrant This static function calls \a functor after a given time interval. It is very convenient to use this function because you do not need to bother with a \l{QObject::timerEvent()}{timerEvent} or create a local QTimer object. The time interval is \a msec milliseconds. The \a timerType affects the accuracy of the timer. If \a context is destroyed before the interval occurs, the method will not be called. The function will be run in the thread of \a context. The context's thread must have a running Qt event loop. \sa start() */ /*! \fn void QTimer::singleShot(std::chrono::milliseconds msec, const QObject *receiver, const char *member) \since 5.8 \overload \reentrant This static function calls a slot after a given time interval. It is very convenient to use this function because you do not need to bother with a \l{QObject::timerEvent()}{timerEvent} or create a local QTimer object. The \a receiver is the receiving object and the \a member is the slot. The time interval is given in the duration object \a msec. \sa start() */ /*! \fn void QTimer::singleShot(std::chrono::milliseconds msec, Qt::TimerType timerType, const QObject *receiver, const char *member) \since 5.8 \overload \reentrant This static function calls a slot after a given time interval. It is very convenient to use this function because you do not need to bother with a \l{QObject::timerEvent()}{timerEvent} or create a local QTimer object. The \a receiver is the receiving object and the \a member is the slot. The time interval is given in the duration object \a msec. The \a timerType affects the accuracy of the timer. \sa start() */ /*! \fn void QTimer::start(std::chrono::milliseconds msec) \since 5.8 \overload Starts or restarts the timer with a timeout of duration \a msec milliseconds. If the timer is already running, it will be \l{QTimer::stop()}{stopped} and restarted. If \l singleShot is true, the timer will be activated only once. */ /*! \fn std::chrono::milliseconds QTimer::intervalAsDuration() const \since 5.8 Returns the interval of this timer as a \c std::chrono::milliseconds object. \sa interval */ /*! \fn std::chrono::milliseconds QTimer::remainingTimeAsDuration() const \since 5.8 Returns the time remaining in this timer object as a \c std::chrono::milliseconds object. If this timer is due or overdue, the returned value is \c std::chrono::milliseconds::zero(). If the remaining time could not be found or the timer is not active, this function returns a negative duration. \sa remainingTime() */ /*! \property QTimer::singleShot \brief whether the timer is a single-shot timer A single-shot timer fires only once, non-single-shot timers fire every \l interval milliseconds. The default value for this property is \c false. \sa interval, singleShot() */ /*! \property QTimer::interval \brief the timeout interval in milliseconds The default value for this property is 0. A QTimer with a timeout interval of 0 will time out as soon as all the events in the window system's event queue have been processed. Setting the interval of an active timer changes its timerId(). \sa singleShot */ void QTimer::setInterval(int msec) { inter = msec; if (id != INV_TIMER) { // create new timer QObject::killTimer(id); // restart timer id = QObject::startTimer(msec, Qt::TimerType(type)); } } /*! \property QTimer::remainingTime \since 5.0 \brief the remaining time in milliseconds Returns the timer's remaining value in milliseconds left until the timeout. If the timer is inactive, the returned value will be -1. If the timer is overdue, the returned value will be 0. \sa interval */ int QTimer::remainingTime() const { if (id != INV_TIMER) { return QAbstractEventDispatcher::instance()->remainingTime(id); } return -1; } /*! \property QTimer::timerType \brief controls the accuracy of the timer The default value for this property is \c Qt::CoarseTimer. \sa Qt::TimerType */ QT_END_NAMESPACE #include "qtimer.moc" #include "moc_qtimer.cpp"