QTimer Class Reference

\inmodule QtCore More...

#include <qtimer.h>

Inheritance diagram for QTimer:

Collaboration diagram for QTimer:

Public Slots
void	start (int msec)
	Starts or restarts the timer with a timeout interval of msec milliseconds.
void	start ()
void	stop ()
	Stops the timer.
Public Slots inherited from QObject
void	deleteLater ()
	\threadsafe

Signals
void	timeout (QPrivateSignal)
	This signal is emitted when the timer times out.
Signals inherited from QObject
void	destroyed (QObject *=nullptr)
	This signal is emitted immediately before the object obj is destroyed, after any instances of QPointer have been notified, and cannot be blocked.
void	objectNameChanged (const QString &objectName, QPrivateSignal)
	This signal is emitted after the object's name has been changed.

Public Member Functions
	QTimer (QObject *parent=nullptr)
	Constructs a timer with the given parent.
	~QTimer ()
	Destroys the timer.
bool	isActive () const
	Returns true if the timer is running (pending); otherwise returns false.
QBindable< bool >	bindableActive ()
int	timerId () const
	Returns the ID of the timer if the timer is running; otherwise returns -1.
void	setInterval (int msec)
int	interval () const
QBindable< int >	bindableInterval ()
int	remainingTime () const
void	setTimerType (Qt::TimerType atype)
Qt::TimerType	timerType () const
QBindable< Qt::TimerType >	bindableTimerType ()
void	setSingleShot (bool singleShot)
bool	isSingleShot () const
QBindable< bool >	bindableSingleShot ()
template<typename ... Args>
QMetaObject::Connection	callOnTimeout (Args &&...args)
void	setInterval (std::chrono::milliseconds value)
std::chrono::milliseconds	intervalAsDuration () const
std::chrono::milliseconds	remainingTimeAsDuration () const
void	start (std::chrono::milliseconds value)
Public Member Functions inherited from QObject
Q_INVOKABLE	QObject (QObject *parent=nullptr)
	Constructs an object with parent object parent.
virtual	~QObject ()
	Destroys the object, deleting all its child objects.
virtual bool	event (QEvent *event)
	This virtual function receives events to an object and should return true if the event e was recognized and processed.
virtual bool	eventFilter (QObject *watched, QEvent *event)
	Filters events if this object has been installed as an event filter for the watched object.
QString	objectName () const
Q_WEAK_OVERLOAD void	setObjectName (const QString &name)
	Sets the object's name to name.
void	setObjectName (QAnyStringView name)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
QBindable< QString >	bindableObjectName ()
bool	isWidgetType () const
	Returns true if the object is a widget; otherwise returns false.
bool	isWindowType () const
	Returns true if the object is a window; otherwise returns false.
bool	isQuickItemType () const
	Returns true if the object is a QQuickItem; otherwise returns false.
bool	signalsBlocked () const noexcept
	Returns true if signals are blocked; otherwise returns false.
bool	blockSignals (bool b) noexcept
	If block is true, signals emitted by this object are blocked (i.e., emitting a signal will not invoke anything connected to it).
QThread *	thread () const
	Returns the thread in which the object lives.
void	moveToThread (QThread *thread)
	Changes the thread affinity for this object and its children.
int	startTimer (int interval, Qt::TimerType timerType=Qt::CoarseTimer)
	This is an overloaded function that will start a timer of type timerType and a timeout of interval milliseconds.
int	startTimer (std::chrono::milliseconds time, Qt::TimerType timerType=Qt::CoarseTimer)
void	killTimer (int id)
	Kills the timer with timer identifier, id.
template<typename T >
T	findChild (const QString &aName=QString(), Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	Returns the child of this object that can be cast into type T and that is called name, or \nullptr if there is no such object.
template<typename T >
QList< T >	findChildren (const QString &aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	Returns all children of this object with the given name that can be cast to type T, or an empty list if there are no such objects.
template<typename T >
QList< T >	findChildren (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
const QObjectList &	children () const
	Returns a list of child objects.
void	setParent (QObject *parent)
	Makes the object a child of parent.
void	installEventFilter (QObject *filterObj)
	Installs an event filter filterObj on this object.
void	removeEventFilter (QObject *obj)
	Removes an event filter object obj from this object.
QMetaObject::Connection	connect (const QObject *sender, const char *signal, const char *member, Qt::ConnectionType type=Qt::AutoConnection) const
bool	disconnect (const char *signal=nullptr, const QObject *receiver=nullptr, const char *member=nullptr) const
bool	disconnect (const QObject *receiver, const char *member=nullptr) const
void	dumpObjectTree () const
	Dumps a tree of children to the debug output.
void	dumpObjectInfo () const
	Dumps information about signal connections, etc.
bool	setProperty (const char *name, const QVariant &value)
	Sets the value of the object's name property to value.
bool	setProperty (const char *name, QVariant &&value)
QVariant	property (const char *name) const
	Returns the value of the object's name property.
QList< QByteArray >	dynamicPropertyNames () const
QBindingStorage *	bindingStorage ()
const QBindingStorage *	bindingStorage () const
QObject *	parent () const
	Returns a pointer to the parent object.
bool	inherits (const char *classname) const
	Returns true if this object is an instance of a class that inherits className or a QObject subclass that inherits className; otherwise returns false.

Static Public Member Functions
static void	singleShot (int msec, const QObject *receiver, const char *member)
	\reentrant This static function calls a slot after a given time interval.
static void	singleShot (int msec, Qt::TimerType timerType, const QObject *receiver, const char *member)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. \reentrant This static function calls a slot after a given time interval.
template<typename Duration , typename Functor >
static void	singleShot (Duration interval, const typename QtPrivate::ContextTypeForFunctor< Functor >::ContextType *receiver, Functor &&slot)
template<typename Duration , typename Functor >
static void	singleShot (Duration interval, Qt::TimerType timerType, const typename QtPrivate::ContextTypeForFunctor< Functor >::ContextType *receiver, Functor &&slot)
template<typename Duration , typename Functor >
static void	singleShot (Duration interval, Functor &&slot)
template<typename Duration , typename Functor >
static void	singleShot (Duration interval, Qt::TimerType timerType, Functor &&slot)
static void	singleShot (std::chrono::milliseconds value, const QObject *receiver, const char *member)
static void	singleShot (std::chrono::milliseconds value, Qt::TimerType timerType, const QObject *receiver, const char *member)
Static Public Member Functions inherited from QObject
static QMetaObject::Connection	connect (const QObject *sender, const char *signal, const QObject *receiver, const char *member, Qt::ConnectionType=Qt::AutoConnection)
	\threadsafe
static QMetaObject::Connection	connect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &method, Qt::ConnectionType type=Qt::AutoConnection)
template<typename Func1 , typename Func2 >
static QMetaObject::Connection	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, const typename QtPrivate::ContextTypeForFunctor< Func2 >::ContextType *context, Func2 &&slot, Qt::ConnectionType type=Qt::AutoConnection)
template<typename Func1 , typename Func2 >
static QMetaObject::Connection	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, Func2 &&slot)
static bool	disconnect (const QObject *sender, const char *signal, const QObject *receiver, const char *member)
	\threadsafe
static bool	disconnect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &member)
static bool	disconnect (const QMetaObject::Connection &)
	Disconnect a connection.
template<typename Func1 , typename Func2 >
static bool	disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, const typename QtPrivate::FunctionPointer< Func2 >::Object *receiver, Func2 slot)
template<typename Func1 >
static bool	disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, const QObject *receiver, void **zero)

Protected Member Functions
void	timerEvent (QTimerEvent *) override
	\reimp
Protected Member Functions inherited from QObject
QObject *	sender () const
	Returns a pointer to the object that sent the signal, if called in a slot activated by a signal; otherwise it returns \nullptr.
int	senderSignalIndex () const
int	receivers (const char *signal) const
	Returns the number of receivers connected to the signal.
bool	isSignalConnected (const QMetaMethod &signal) const
virtual void	timerEvent (QTimerEvent *event)
	This event handler can be reimplemented in a subclass to receive timer events for the object.
virtual void	childEvent (QChildEvent *event)
	This event handler can be reimplemented in a subclass to receive child events.
virtual void	customEvent (QEvent *event)
	This event handler can be reimplemented in a subclass to receive custom events.
virtual void	connectNotify (const QMetaMethod &signal)
virtual void	disconnectNotify (const QMetaMethod &signal)
	QObject (QObjectPrivate &dd, QObject *parent=nullptr)

Properties
bool	singleShot
	whether the timer is a single-shot timer
int	interval
	the timeout interval in milliseconds
int	remainingTime
	the remaining time in milliseconds
Qt::TimerType	timerType
	controls the accuracy of the timer
bool	active
Properties inherited from QObject
QString	objectName
	the name of this object

Additional Inherited Members
Protected Attributes inherited from QObject
QScopedPointer< QObjectData >	d_ptr
Related Symbols inherited from QObject
template< class T > T	qobject_cast (const QObject *object)
	Returns the given object cast to type T if the object is of type T (or of a subclass); otherwise returns \nullptr.
template< typename T > T	qFindChildqFindChildren (const QObject *obj, const QString &name)()
template< typename T > QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QString &name)()
	QObjectList
	\macro Q_CLASSINFO(Name, Value)

Detailed Description

\inmodule QtCore

The QTimer class provides repetitive and single-shot timers.

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):

From then on, the 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:

    QTimer::singleShot(200, this, &Foo::updateCaption);

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 possible, though the ordering between zero timers and other sources of events is unspecified. Zero timers can be used to do some work while still providing a snappy user interface:

    QTimer *timer = new QTimer(this);

    connect(timer, &QTimer::timeout, this, &Foo::processOneThing);

    timer->start();

From then on, 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.

Definition at line 19 of file qtimer.h.

Constructor & Destructor Documentation

QTimer()

QTimer::QTimer ( QObject *  parent = nullptr )

explicit

Constructs a timer with the given parent.

Definition at line 117 of file qtimer.cpp.

~QTimer()

QTimer::~QTimer

(

)

Destroys the timer.

Definition at line 127 of file qtimer.cpp.

References QTimerPrivate::INV_TIMER, and stop().

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Member Function Documentation

bindableActive()

QBindable< bool > QTimer::bindableActive

(

)

Definition at line 161 of file qtimer.cpp.

bindableInterval()

QBindable< int > QTimer::bindableInterval

(

)

Definition at line 627 of file qtimer.cpp.

bindableSingleShot()

QBindable< bool > QTimer::bindableSingleShot

(

)

Definition at line 590 of file qtimer.cpp.

bindableTimerType()

QBindable< Qt::TimerType > QTimer::bindableTimerType

(

)

Definition at line 671 of file qtimer.cpp.

callOnTimeout()

template<typename ... Args>

template< typename Functor > QMetaObject::Connection QTimer::callOnTimeout ( Args &&...  args )

inline

Since

5.12

Creates a connection of type connectionType from the timeout() signal to slot, and returns a handle to the connection.

This method is provided for convenience. It's equivalent to calling {QObject::connect(timer, &QTimer::timeout, timer, slot, connectionType)}.

See also

QObject::connect(), timeout()

Definition at line 97 of file qtimer.h.

References args, QObject::connect(), and timeout().

Referenced by MFPlayerSession::MFPlayerSession(), QWindowsAudioSource::QWindowsAudioSource(), QWindowsAudioSink::start(), and QWindowsAudioSink::start().

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interval()

int QTimer::interval

(

)

const

Definition at line 622 of file qtimer.cpp.

intervalAsDuration()

std::chrono::milliseconds QTimer::intervalAsDuration ( ) const

inline

Since

5.8

Returns the interval of this timer as a std::chrono::milliseconds object.

See also

interval

Definition at line 119 of file qtimer.h.

isActive()

bool QTimer::isActive

(

)

const

Returns true if the timer is running (pending); otherwise returns false.

Definition at line 156 of file qtimer.cpp.

Referenced by QGeoPositionInfoSourceAndroid::~QGeoPositionInfoSourceAndroid(), QGeoSatelliteInfoSourceAndroid::~QGeoSatelliteInfoSourceAndroid(), QPollingFileSystemWatcherEngine::addPaths(), QComboBoxPrivateContainer::eventFilter(), QSmoothedAnimation::init(), QDBusTrayIcon::isRequestingAttention(), QComboBoxPrivateContainer::mouseReleaseEvent(), QNmeaSatelliteInfoSourcePrivate::notifyNewUpdate(), QNmeaPositionInfoSourcePrivate::notifyNewUpdate(), QGeoPositionInfoSourceAndroid::processPositionUpdate(), QGeoSatelliteInfoSourceAndroid::processSatelliteUpdate(), QGeoPositionInfoSourceAndroid::processSinglePositionUpdate(), QNmeaSatelliteSimulationReader::readAvailableData(), QNmeaPositionInfoSourcePrivate::requestUpdate(), QNmeaSatelliteInfoSourcePrivate::requestUpdate(), QGeoPositionInfoSourceAndroid::requestUpdate(), QGeoSatelliteInfoSourceAndroid::requestUpdate(), QGeoPositionInfoSourceGeoclue2::requestUpdate(), QQuickSelectionRectanglePrivate::scrollTowardsPos(), QNmeaSatelliteSimulationReader::setUpdateInterval(), QHttpNetworkConnectionPrivate::shouldEmitChannelError(), QGeoSatelliteInfoSourceGypsy::startUpdates(), QWinRTBluetoothDeviceDiscoveryWorker::stop(), QGeoSatelliteInfoSourceGypsy::stopUpdates(), QOpenGLCompositor::update(), and QAndroidInputContext::updateSelectionHandles().

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isSingleShot()

bool QTimer::isSingleShot

(

)

const

Definition at line 585 of file qtimer.cpp.

remainingTime()

int QTimer::remainingTime

(

)

const

Definition at line 643 of file qtimer.cpp.

References d, QAbstractEventDispatcher::instance(), QTimerPrivate::INV_TIMER, and QAbstractEventDispatcher::remainingTime().

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remainingTimeAsDuration()

std::chrono::milliseconds QTimer::remainingTimeAsDuration ( ) const

inline

Since

5.8

Returns the time remaining in this timer object as a std::chrono::milliseconds object. If this timer is due or overdue, the returned value is std::chrono::milliseconds::zero(). If the remaining time could not be found or the timer is not active, this function returns a negative duration.

See also

remainingTime()

Definition at line 124 of file qtimer.h.

Referenced by QLockFile::tryLock().

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setInterval() [1/2]

void QTimer::setInterval

(

int

msec

)

Definition at line 607 of file qtimer.cpp.

References d, QTimerPrivate::INV_TIMER, QObject::killTimer(), and QObject::startTimer().

Referenced by BluetoothManagement::BluetoothManagement(), QmlJSDebugger::InspectTool::InspectTool(), MFPlayerSession::MFPlayerSession(), QAndroidCaptureSession::QAndroidCaptureSession(), QAndroidInputContext::QAndroidInputContext(), QFFmpegMediaPlayer::QFFmpegMediaPlayer(), QGstPipelinePrivate::QGstPipelinePrivate(), QNmeaRealTimeReader::QNmeaRealTimeReader(), QPcscCard::QPcscCard(), QQmlDebugConnectionPrivate::QQmlDebugConnectionPrivate(), QQmlPreviewHandler::QQmlPreviewHandler(), QQmlPreviewPosition::QQmlPreviewPosition(), QQnxAudioSink::QQnxAudioSink(), QQnxMediaPlayer::QQnxMediaPlayer(), QQnxWindowGrabber::QQnxWindowGrabber(), QQuick3DParticleSystem::QQuick3DParticleSystem(), QSmoothedAnimation::QSmoothedAnimation(), QWindowsMediaDeviceReader::QWindowsMediaDeviceReader(), QWinRTBluetoothDeviceDiscoveryWorker::QWinRTBluetoothDeviceDiscoveryWorker(), QQuick3DParticleSystem::componentComplete(), QQmlProfilerServiceImpl::messageReceived(), QGeoSatelliteInfoSourceGypsy::requestUpdate(), QQnxWindowGrabber::setFrameRate(), QNearFieldTargetPrivateImpl::setupTargetCheckTimer(), QNetworkReplyHttpImplPrivate::setupTransferTimeout(), QWasmAudioSink::start(), and QWasmAudioSource::start().

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setInterval() [2/2]

void QTimer::setInterval ( std::chrono::milliseconds  value )

inline

Definition at line 114 of file qtimer.h.

setSingleShot()

void QTimer::setSingleShot

(

bool

singleShot

)

Definition at line 580 of file qtimer.cpp.

References singleShot.

Referenced by QmlJSDebugger::InspectTool::InspectTool(), QAndroidInputContext::QAndroidInputContext(), QComboBoxPrivateContainer::QComboBoxPrivateContainer(), QDBusTrayIcon::QDBusTrayIcon(), QGeoAreaMonitorPollingPrivate::QGeoAreaMonitorPollingPrivate(), QGeoPositionInfoSourceAndroid::QGeoPositionInfoSourceAndroid(), QGeoPositionInfoSourceGeoclue2::QGeoPositionInfoSourceGeoclue2(), QGeoSatelliteInfoSourceAndroid::QGeoSatelliteInfoSourceAndroid(), QGeoSatelliteInfoSourceGypsy::QGeoSatelliteInfoSourceGypsy(), QIBusPlatformInputContext::QIBusPlatformInputContext(), QMoviePrivate::QMoviePrivate(), QNmeaRealTimeReader::QNmeaRealTimeReader(), QQmlDebugConnectionPrivate::QQmlDebugConnectionPrivate(), QQmlPreviewPosition::QQmlPreviewPosition(), QQnxAudioSink::QQnxAudioSink(), QQnxMediaPlayer::QQnxMediaPlayer(), QSmoothedAnimation::QSmoothedAnimation(), QWasmAudioSink::QWasmAudioSink(), QWindowsAudioSink::QWindowsAudioSink(), QWindowsAudioSource::QWindowsAudioSource(), QWinRTBluetoothDeviceDiscoveryWorker::QWinRTBluetoothDeviceDiscoveryWorker(), QFileSystemModelPrivate::init(), QHttpNetworkConnectionPrivate::init(), QNetworkReplyHttpImplPrivate::setupTransferTimeout(), and QFFmpeg::PlaybackEngineObject::timer().

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setTimerType()

void QTimer::setTimerType

(

Qt::TimerType

atype

)

Definition at line 661 of file qtimer.cpp.

Referenced by BluetoothManagement::BluetoothManagement(), MFPlayerSession::MFPlayerSession(), QAndroidInputContext::QAndroidInputContext(), QFFmpegMediaPlayer::QFFmpegMediaPlayer(), QWindowsAudioSink::QWindowsAudioSink(), QWindowsAudioSource::QWindowsAudioSource(), and QFFmpeg::PlaybackEngineObject::timer().

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singleShot() [1/8]

template<typename Duration , typename Functor >

static void QTimer::singleShot ( Duration  interval, const typename QtPrivate::ContextTypeForFunctor< Functor >::ContextType *  receiver, Functor &&  slot  )

inlinestatic

Definition at line 54 of file qtimer.h.

singleShot() [2/8]

template<typename Duration , typename Functor >

template< typename Duration, typename Functor > void QTimer::singleShot ( Duration  interval, Functor &&  slot  )

inlinestatic

Definition at line 80 of file qtimer.h.

singleShot() [3/8]

template<typename Duration , typename Functor >

static void QTimer::singleShot ( Duration  interval, Qt::TimerType  timerType, const typename QtPrivate::ContextTypeForFunctor< Functor >::ContextType *  receiver, Functor &&  slot  )

inlinestatic

Definition at line 66 of file qtimer.h.

References void.

singleShot() [4/8]

template<typename Duration , typename Functor >

template< typename Duration, typename Functor > void QTimer::singleShot ( Duration  msec, Qt::TimerType  timerType, Functor &&  functor  )

inlinestatic

Since

5.4

\reentrant This static function calls functor after msec milliseconds.

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.

If context is specified, then the functor will be called only if the context object has not been destroyed before the interval occurs. The functor will then be run the thread of context. The context's thread must have a running Qt event loop.

If functor is a member function of context, then the function will be called on the object.

The msec parameter can be an int or a std::chrono::milliseconds value.

See also

start()

Definition at line 85 of file qtimer.h.

singleShot() [5/8]

void QTimer::singleShot ( int  msec, const QObject *  receiver, const char *  member  )

static

\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:

#include <QApplication>
#include <QTimer>
 
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QTimer::singleShot(600000, &app, QCoreApplication::quit);
    ...
    return app.exec();
}

This sample program automatically terminates after 10 minutes (600,000 milliseconds).

The receiver is the receiving object and the member is the slot. The time interval is msec milliseconds.

See also

start()

Definition at line 400 of file qtimer.cpp.

References Qt::CoarseTimer, Qt::PreciseTimer, and singleShot.

singleShot() [6/8]

void QTimer::singleShot ( int  msec, Qt::TimerType  timerType, const QObject *  receiver, const char *  member  )

static

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. \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 receiver is the receiving object and the member is the slot. The time interval is msec milliseconds. The timerType affects the accuracy of the timer.

See also

start()

Definition at line 422 of file qtimer.cpp.

References QString::constData(), QMetaObject::invokeMethod(), methodName(), Q_UNLIKELY, Qt::QueuedConnection, qWarning, timerType, and void.

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singleShot() [7/8]

void QTimer::singleShot ( std::chrono::milliseconds  msec, const QObject *  receiver, const char *  member  )

inlinestatic

Since

5.8 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. \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 receiver is the receiving object and the member is the slot. The time interval is given in the duration object msec.

See also

start()

Definition at line 129 of file qtimer.h.

singleShot() [8/8]

void QTimer::singleShot ( std::chrono::milliseconds  msec, Qt::TimerType  timerType, const QObject *  receiver, const char *  member  )

inlinestatic

Since

5.8 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. \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 receiver is the receiving object and the member is the slot. The time interval is given in the duration object msec. The timerType affects the accuracy of the timer.

See also

start()

Definition at line 134 of file qtimer.h.

start [1/3]

void QTimer::start ( )

slot

Definition at line 187 of file qtimer.cpp.

References d, QTimerPrivate::INV_TIMER, QObject::startTimer(), and stop().

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start [2/3]

void QTimer::start ( int  msec )

slot

Starts or restarts the timer with a timeout interval of 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.

Note

Keeping the event loop busy with a zero-timer is bound to cause trouble and highly erratic behavior of the UI.

Definition at line 208 of file qtimer.cpp.

References d, and start().

Referenced by BluetoothManagement::BluetoothManagement(), Foo::Foo(), QGstPipelinePrivate::QGstPipelinePrivate(), QNearFieldTargetPrivateImpl::QNearFieldTargetPrivateImpl(), QNearFieldTargetPrivateImpl::QNearFieldTargetPrivateImpl(), QPdfDocumentPrivate::QPdfDocumentPrivate(), QAbstractSocketPrivate::_q_connectToNextAddress(), QLocalSocketPrivate::_q_connectToSocket(), QMoviePrivate::_q_loadNextFrame(), QPollingFileSystemWatcherEngine::addPaths(), await(), QXcbClipboard::clipboardReadIncrementalProperty(), QXcbWindow::doFocusOut(), QPdfSearchModelPrivate::doSearch(), executeOperationsForTime(), executeSlowOperations(), QSSGRenderer::getShaderPipelineForDefaultMaterial(), QAndroidInputContext::hideSelectionHandles(), QProgressDialogPrivate::init(), main(), QQmlProfilerServiceImpl::messageReceived(), QPcscManager::onStartTargetDetectionRequest(), AVFMediaPlayer::play(), QGstreamerMediaPlayer::play(), AVFMediaPlayer::processBufferStateChange(), AVFMediaPlayer::processLoadStateChange(), qWaitForSignal(), QNmeaRealTimeReader::readAvailableData(), QNmeaSatelliteSimulationReader::readAvailableData(), QGstreamerMediaEncoder::record(), QPdfDocument::render(), QNmeaPositionInfoSourcePrivate::requestUpdate(), QNmeaSatelliteInfoSourcePrivate::requestUpdate(), QGeoPositionInfoSourceAndroid::requestUpdate(), QGeoSatelliteInfoSourceAndroid::requestUpdate(), QGeoPositionInfoSourceGeoclue2::requestUpdate(), QGeoSatelliteInfoSourceGypsy::requestUpdate(), restartExample(), QQnxWindowGrabber::resume(), QAlsaAudioSink::resume(), QAlsaAudioSource::resume(), QPulseAudioSource::resume(), QGstreamerMediaEncoder::resume(), QAlphaWidget::run(), QRollEffect::run(), QFFmpeg::PlaybackEngineObject::scheduleNextStep(), QQuickSelectionRectanglePrivate::scrollTowardsPos(), QNearFieldTargetPrivateImpl::setIntent(), QQuick3DParticleSystem::setLogging(), QQnxMediaPlayer::setPosition(), QNmeaSatelliteSimulationReader::setUpdateInterval(), QNearFieldTargetPrivateImpl::setupTargetCheckTimer(), QSSGCustomMaterialSystem::shadersForCustomMaterial(), QDBusTrayIcon::showMessage(), QComboBoxPrivate::showPopupFromMouseEvent(), QIBusPlatformInputContext::socketChanged(), QWinRTBluetoothDeviceDiscoveryWorker::start(), QQnxWindowGrabber::start(), QWasmAudioSink::start(), QWasmAudioSource::start(), start(), QQnxAudioSink::start(), QAndroidCaptureSession::start(), startExample(), QDarwinAudioSinkBuffer::startFillTimer(), QDarwinAudioSourceBuffer::startFlushTimer(), QHttpNetworkConnectionPrivate::startNetworkLayerStateLookup(), QWindowsMediaDeviceReader::startRecording(), QComboBoxPrivateScroller::startTimer(), QGeoPositionInfoSourceAndroid::startUpdates(), QTlsPrivate::systemCaCertificates(), QQmlPreviewPosition::takePosition(), QOpenGLCompositor::update(), QAndroidInputContext::updateSelectionHandles(), QNearFieldTargetPrivate::waitForRequestCompleted(), and waitForWindowExposed().

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start() [3/3]

void QTimer::start ( std::chrono::milliseconds  msec )

inline

Since

5.8 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Starts or restarts the timer with a timeout of duration 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.

Definition at line 139 of file qtimer.h.

stop

void QTimer::stop ( )

slot

Stops the timer.

See also

start()

Definition at line 226 of file qtimer.cpp.

References d, QTimerPrivate::INV_TIMER, and QObject::killTimer().

Referenced by QQuickSelectionRectanglePrivate::QQuickSelectionRectanglePrivate(), QGeoPositionInfoSourceAndroid::~QGeoPositionInfoSourceAndroid(), QGeoSatelliteInfoSourceAndroid::~QGeoSatelliteInfoSourceAndroid(), ~QTimer(), QAbstractSocketPrivate::_q_abortConnectionAttempt(), QAbstractSocketPrivate::_q_testConnection(), QLocalSocketPrivate::cancelDelayedConnect(), MFPlayerSession::close(), QComboBoxPrivateContainer::eventFilter(), QNetworkReplyHttpImplPrivate::finished(), QXcbWindow::handleFocusInEvent(), QXcbWindow::handleXEmbedMessage(), QSmoothedAnimation::init(), QNearFieldTargetPrivateImpl::invalidate(), QMoviePrivate::jumpToFrame(), QQmlProfilerServiceImpl::messageReceived(), QNmeaRealTimeReader::notifyNewUpdate(), QNmeaSatelliteInfoSourcePrivate::notifyNewUpdate(), QNmeaPositionInfoSourcePrivate::notifyNewUpdate(), QQnxWindowGrabber::pause(), AVFMediaPlayer::pause(), QFFmpegMediaPlayer::pause(), QGstreamerMediaPlayer::pause(), QGstreamerMediaEncoder::pause(), QGeoPositionInfoSourceAndroid::processPositionUpdate(), QGeoSatelliteInfoSourceAndroid::processSatelliteUpdate(), QGeoPositionInfoSourceAndroid::processSinglePositionUpdate(), QNmeaRealTimeReader::readAvailableData(), QNearFieldTargetPrivateImpl::releaseIntent(), QPollingFileSystemWatcherEngine::removePaths(), QAlphaWidget::render(), QGeoPositionInfoSourceAndroid::requestUpdate(), QGeoSatelliteInfoSourceAndroid::requestUpdate(), QMoviePrivate::reset(), QAbstractSocketPrivate::resetSocketLayer(), QGeoSatelliteInfoSourceGypsy::satellitesChanged(), QFFmpeg::PlaybackEngineObject::scheduleNextStep(), QQuick3DParticleSystem::setLogging(), QNetworkReplyHttpImplPrivate::setupTransferTimeout(), QHttpNetworkConnectionPrivate::shouldEmitChannelError(), QIBusPlatformInputContext::socketChanged(), start(), QBluetoothDeviceDiscoveryAgentPrivate::start(), QWinRTBluetoothDeviceDiscoveryWorker::stop(), QQnxWindowGrabber::stop(), QWasmAudioSink::stop(), QWasmAudioSource::stop(), AVFMediaPlayer::stop(), QFFmpegMediaPlayer::stop(), QGstreamerMediaEncoder::stop(), QAndroidCaptureSession::stop(), QDarwinAudioSinkBuffer::stopFillTimer(), QDarwinAudioSourceBuffer::stopFlushTimer(), QWindowsMediaDeviceReader::stopRecording(), QComboBoxPrivateScroller::stopTimer(), QGeoPositionInfoSourceAndroid::stopUpdates(), QAlsaAudioSink::suspend(), QAlsaAudioSource::suspend(), QPulseAudioSource::suspend(), timerEvent(), QAndroidInputContext::touchDown(), QmlJSDebugger::InspectTool::touchEvent(), QNmeaSatelliteInfoSourcePrivate::updateRequestTimeout(), and QAndroidInputContext::updateSelectionHandles().

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timeout

void QTimer::timeout ( QPrivateSignal  )

signal

This signal is emitted when the timer times out.

See also

interval, start(), stop()

Referenced by AVFMediaPlayer::AVFMediaPlayer(), BluetoothManagement::BluetoothManagement(), Foo::Foo(), QmlJSDebugger::InspectTool::InspectTool(), Operation::Operation(), QAndroidCaptureSession::QAndroidCaptureSession(), QAndroidInputContext::QAndroidInputContext(), QFFmpegMediaPlayer::QFFmpegMediaPlayer(), QGeoMapMapboxGL::QGeoMapMapboxGL(), QGeoPositionInfoSourceAndroid::QGeoPositionInfoSourceAndroid(), QGeoPositionInfoSourceGeoclue2::QGeoPositionInfoSourceGeoclue2(), QLibInputKeyboard::QLibInputKeyboard(), QNearFieldTargetPrivateImpl::QNearFieldTargetPrivateImpl(), QNearFieldTargetPrivateImpl::QNearFieldTargetPrivateImpl(), QNmeaRealTimeReader::QNmeaRealTimeReader(), QNmeaSatelliteSimulationReader::QNmeaSatelliteSimulationReader(), QPcscCard::QPcscCard(), QPcscManager::QPcscManager(), QQmlDebugConnection::QQmlDebugConnection(), QQmlDebugTranslationServicePrivate::QQmlDebugTranslationServicePrivate(), QQmlPreviewHandler::QQmlPreviewHandler(), QQmlPreviewPosition::QQmlPreviewPosition(), QQnxAudioSink::QQnxAudioSink(), QQnxMediaPlayer::QQnxMediaPlayer(), QQnxWindowGrabber::QQnxWindowGrabber(), QQuickSelectionRectanglePrivate::QQuickSelectionRectanglePrivate(), QSmoothedAnimationTimer::QSmoothedAnimationTimer(), QWasmAudioSink::QWasmAudioSink(), QWasmAudioSource::QWasmAudioSource(), QWindowsMediaDeviceReader::QWindowsMediaDeviceReader(), QWinRTBluetoothDeviceDiscoveryWorker::QWinRTBluetoothDeviceDiscoveryWorker(), QQuickViewTestUtils::StressTestModel::StressTestModel(), callOnTimeout(), QQuick3DParticleSystem::componentComplete(), QGeoPositionInfoSourceWinRT::init(), QQmlProfilerServiceImpl::messageReceived(), QBluetoothLocalDevicePrivate::requestPairing(), QNearFieldTargetPrivateImpl::setupTargetCheckTimer(), QBluetoothDeviceDiscoveryAgentPrivate::start(), QFFmpeg::PlaybackEngineObject::timer(), and timerEvent().

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timerEvent()

void QTimer::timerEvent ( QTimerEvent *  e )

overrideprotectedvirtual

\reimp

Reimplemented from QObject.

Definition at line 240 of file qtimer.cpp.

References d, e, emit, stop(), and timeout().

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timerId()

int QTimer::timerId

(

)

const

Returns the ID of the timer if the timer is running; otherwise returns -1.

Definition at line 172 of file qtimer.cpp.

Referenced by QComboBoxPrivateScroller::timerEvent().

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timerType()

Qt::TimerType QTimer::timerType

(

)

const

Definition at line 666 of file qtimer.cpp.

Property Documentation

active

QTimer::active

read

Since

4.3

This boolean property is true if the timer is running; otherwise false.

Definition at line 170 of file qtimer.h.

interval

QTimer::interval

readwrite

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().

See also

singleShot

Definition at line 170 of file qtimer.h.

remainingTime

QTimer::remainingTime

read

the remaining time in milliseconds

Since

5.0

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.

See also

interval

Definition at line 170 of file qtimer.h.

singleShot

QTimer::singleShot

readwrite

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 false.

See also

interval, singleShot()

Definition at line 170 of file qtimer.h.

Referenced by Foo::Foo(), MFVideoRendererControl::customEvent(), QmlLsp::QmlLintSuggestions::diagnose(), ensureAuthorizationDialogNotBlocked(), QLineEdit::event(), QMenuPrivate::hideMenu(), QComboBox::hidePopup(), main(), QV4::QObjectMethod::method_destroy(), QQmlBindPrivate::onDelayedValueChanged(), quick_test_main_with_setup(), QQmlXmlListModel::reload(), FileInfoThread::runOnce(), RemoteDeviceManager::scheduleJob(), QSyntaxHighlighter::setDocument(), setSingleShot(), AudioInputExample::setup(), QCocoaMessageDialog::show(), QmlJSDebugger::SelectionHighlight::showName(), singleShot(), QHttpThreadDelegate::startRequestSynchronously(), QGeoTileRequestManagerPrivate::tileError(), QQmlPreviewHandler::zoom(), QWaylandTextureSharingExtension::zqt_texture_sharing_v1_abandon_image(), and QWaylandTextureSharingExtension::zqt_texture_sharing_v1_destroy_resource().

timerType

QTimer::timerType

readwrite

controls the accuracy of the timer

The default value for this property is Qt::CoarseTimer.

See also

Qt::TimerType

Definition at line 170 of file qtimer.h.

Referenced by singleShot().

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The documentation for this class was generated from the following files:

• qtbase/src/corelib/kernel/qtimer.h
• qtbase/src/corelib/kernel/qtimer.cpp