The QTimer class provides repetitive and single-shot timers. More...

#include <qtimer.h>

Inheritance diagram for QTimer:

Collaboration diagram for QTimer:

Public Slots
void	start (int msec)

void	start ()

void	stop ()

Public Slots inherited from QObject
void	deleteLater ()

Signals
void	timeout (QPrivateSignal)

Signals inherited from QObject
void	destroyed (QObject *=nullptr)

void	objectNameChanged (const QString &objectName, QPrivateSignal)

Public Member Functions
	QTimer (QObject *parent=nullptr)

	~QTimer ()

bool	isActive () const

QBindable< bool >	bindableActive ()

int	timerId () const

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)

Public Member Functions inherited from QObject
Q_INVOKABLE	QObject (QObject *parent=nullptr)

virtual	~QObject ()

virtual bool	event (QEvent *event)

virtual bool	eventFilter (QObject watched, QEvent event)

QString	objectName () const

void	setObjectName (const QString &name)

QBindable< QString >	bindableObjectName ()

bool	isWidgetType () const

bool	isWindowType () const

bool	signalsBlocked () const noexcept

bool	blockSignals (bool b) noexcept

QThread *	thread () const

void	moveToThread (QThread *thread)

int	startTimer (int interval, Qt::TimerType timerType=Qt::CoarseTimer)

void	killTimer (int id)

template<typename T >
T	findChild (const QString &aName=QString(), Qt::FindChildOptions options=Qt::FindChildrenRecursively) const

template<typename T >
QList< T >	findChildren (const QString &aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const

template<typename T >
QList< T >	findChildren (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const

const QObjectList &	children () const

void	setParent (QObject *parent)

void	installEventFilter (QObject *filterObj)

void	removeEventFilter (QObject *obj)

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

void	dumpObjectInfo () const

bool	setProperty (const char *name, const QVariant &value)

QVariant	property (const char *name) const

QList< QByteArray >	dynamicPropertyNames () const

QBindingStorage *	bindingStorage ()

const QBindingStorage *	bindingStorage () const

QObject *	parent () const

bool	inherits (const char *classname) const

Static Public Member Functions
static void	singleShot (int msec, const QObject receiver, const char member)

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

template<typename Duration , typename Func1 >
static void	singleShot (Duration interval, const typename QtPrivate::FunctionPointer< Func1 >::Object *receiver, Func1 slot)

template<typename Duration , typename Func1 >
static void	singleShot (Duration interval, Qt::TimerType timerType, const typename QtPrivate::FunctionPointer< Func1 >::Object *receiver, Func1 slot)

template<typename Duration , typename Func1 >
static std::enable_if<!QtPrivate::FunctionPointer< Func1 >::IsPointerToMemberFunction &&!std::is_same< const char *, Func1 >::value, void >::type	singleShot (Duration interval, Func1 slot)

template<typename Duration , typename Func1 >
static std::enable_if<!QtPrivate::FunctionPointer< Func1 >::IsPointerToMemberFunction &&!std::is_same< const char *, Func1 >::value, void >::type	singleShot (Duration interval, Qt::TimerType timerType, Func1 slot)

template<typename Duration , typename Func1 >
static std::enable_if<!QtPrivate::FunctionPointer< Func1 >::IsPointerToMemberFunction &&!std::is_same< const char *, Func1 >::value, void >::type	singleShot (Duration interval, const QObject *context, Func1 slot)

template<typename Duration , typename Func1 >
static std::enable_if<!QtPrivate::FunctionPointer< Func1 >::IsPointerToMemberFunction &&!std::is_same< const char *, Func1 >::value, void >::type	singleShot (Duration interval, Qt::TimerType timerType, const QObject *context, Func1 slot)

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)

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::FunctionPointer< Func2 >::Object receiver, Func2 slot, Qt::ConnectionType type=Qt::AutoConnection)

static QMetaObject::Connection ::type	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, Func2 slot)

static QMetaObject::Connection ::type	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const QObject context, Func2 slot, Qt::ConnectionType type=Qt::AutoConnection)

template<typename Func1 , typename Func2 >
static std::enable_if< QtPrivate::FunctionPointer< Func2 >::ArgumentCount==-1 &&!std::is_convertible_v< Func2, const char * >, QMetaObject::Connection >::type	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, Func2 slot)

template<typename Func1 , typename Func2 >
static std::enable_if< QtPrivate::FunctionPointer< Func2 >::ArgumentCount==-1 &&!std::is_convertible_v< Func2, const char * >, QMetaObject::Connection >::type	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const QObject context, Func2 slot, Qt::ConnectionType type=Qt::AutoConnection)

static bool	disconnect (const QObject sender, const char signal, const QObject receiver, const char member)

static bool	disconnect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &member)

static bool	disconnect (const QMetaObject::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

Protected Member Functions inherited from QObject
QObject *	sender () const

int	senderSignalIndex () const

int	receivers (const char *signal) const

bool	isSignalConnected (const QMetaMethod &signal) const

virtual void	childEvent (QChildEvent *event)

virtual void	customEvent (QEvent *event)

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 More...

int	interval
	the timeout interval in milliseconds More...

int	remainingTime
	the remaining time in milliseconds More...

Qt::TimerType	timerType
	controls the accuracy of the timer More...

bool	active

Properties inherited from QObject
QString	objectName
	the name of this object More...

Additional Inherited Members
Protected Attributes inherited from QObject
QScopedPointer< QObjectData >	d_ptr

Related Functions inherited from QObject
template< class T > T	qobject_cast (const QObject *object)

template< typename T > T	qFindChildqFindChildren (const QObject *obj, const QString &name)()

template< typename T > QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QString &name)()

	QObjectList

Detailed Description

The QTimer class provides repetitive and single-shot timers.

\inmodule QtCore

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:

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:

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 57 of file qtimer.h.

Constructor & Destructor Documentation

◆ QTimer()

QTimer::QTimer ( QObject * parent = nullptr )

explicit

Constructs a timer with the given parent.

Definition at line 167 of file qtimer.cpp.

◆ ~QTimer()

QTimer::~QTimer ( )

Destroys the timer.

Definition at line 177 of file qtimer.cpp.

Member Function Documentation

◆ bindableActive()

QBindable< bool > QTimer::bindableActive ( )

Definition at line 211 of file qtimer.cpp.

◆ bindableInterval()

QBindable< int > QTimer::bindableInterval ( )

Definition at line 777 of file qtimer.cpp.

◆ bindableSingleShot()

QBindable< bool > QTimer::bindableSingleShot ( )

Definition at line 740 of file qtimer.cpp.

◆ bindableTimerType()

QBindable< Qt::TimerType > QTimer::bindableTimerType ( )

Definition at line 821 of file qtimer.cpp.

◆ callOnTimeout()

template<typename ... Args>

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

inline

Since: 5.12 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

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 167 of file qtimer.h.

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◆ interval()

int QTimer::interval ( ) const

Definition at line 772 of file qtimer.cpp.

◆ isActive()

bool QTimer::isActive ( ) const

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

Definition at line 206 of file qtimer.cpp.

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◆ isSingleShot()

bool QTimer::isSingleShot ( ) const

Definition at line 735 of file qtimer.cpp.

◆ remainingTime()

int QTimer::remainingTime ( ) const

Definition at line 793 of file qtimer.cpp.

◆ setInterval()

void QTimer::setInterval ( int msec )

Definition at line 757 of file qtimer.cpp.

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◆ setSingleShot()

void QTimer::setSingleShot ( bool singleShot )

Definition at line 730 of file qtimer.cpp.

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◆ setTimerType()

void QTimer::setTimerType ( Qt::TimerType atype )

Definition at line 811 of file qtimer.cpp.

◆ singleShot() [1/8]

template<typename Duration , typename Func1 >

static std::enable_if<!QtPrivate::FunctionPointer<Func1>::IsPointerToMemberFunction && !std::is_same<const char*, Func1>::value, void>::type QTimer::singleShot	(	Duration	interval,
		const QObject *	context,
		Func1	slot
	)

inlinestatic

Definition at line 148 of file qtimer.h.

◆ singleShot() [2/8]

template<typename Duration , typename Func1 >

static void QTimer::singleShot	(	Duration	interval,
		const typename QtPrivate::FunctionPointer< Func1 >::Object *	receiver,
		Func1	slot
	)

inlinestatic

Definition at line 112 of file qtimer.h.

◆ singleShot() [3/8]

template<typename Duration , typename Func1 >

static std::enable_if<!QtPrivate::FunctionPointer<Func1>::IsPointerToMemberFunction && !std::is_same<const char*, Func1>::value, void>::type QTimer::singleShot	(	Duration	interval,
		Func1	slot
	)

inlinestatic

Definition at line 133 of file qtimer.h.

◆ singleShot() [4/8]

template<typename Duration , typename Func1 >

static std::enable_if<!QtPrivate::FunctionPointer<Func1>::IsPointerToMemberFunction && !std::is_same<const char*, Func1>::value, void>::type QTimer::singleShot	(	Duration	interval,
		Qt::TimerType	timerType,
		const QObject *	context,
		Func1	slot
	)

inlinestatic

Definition at line 155 of file qtimer.h.

◆ singleShot() [5/8]

template<typename Duration , typename Func1 >

static void QTimer::singleShot	(	Duration	interval,
		Qt::TimerType	timerType,
		const typename QtPrivate::FunctionPointer< Func1 >::Object *	receiver,
		Func1	slot
	)

inlinestatic

Definition at line 117 of file qtimer.h.

◆ singleShot() [6/8]

template<typename Duration , typename Func1 >

static std::enable_if<!QtPrivate::FunctionPointer<Func1>::IsPointerToMemberFunction && !std::is_same<const char*, Func1>::value, void>::type QTimer::singleShot	(	Duration	interval,
		Qt::TimerType	timerType,
		Func1	slot
	)

inlinestatic

Definition at line 140 of file qtimer.h.

◆ singleShot() [7/8]

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:

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 438 of file qtimer.cpp.

◆ singleShot() [8/8]

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 460 of file qtimer.cpp.

◆ start [1/2]

void QTimer::start ( )

slot

Definition at line 237 of file qtimer.cpp.

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◆ start [2/2]

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 259 of file qtimer.cpp.

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◆ stop

void QTimer::stop ( )

slot

Stops the timer.

See also: start()

Definition at line 277 of file qtimer.cpp.

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◆ timeout

void QTimer::timeout ( QPrivateSignal )

signal

This signal is emitted when the timer times out.

See also: interval, start(), stop()

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◆ timerEvent()

void QTimer::timerEvent ( QTimerEvent * e )

overrideprotectedvirtual

\reimp

Reimplemented from QObject.

Definition at line 291 of file qtimer.cpp.

◆ timerId()

int QTimer::timerId ( ) const

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

Definition at line 222 of file qtimer.cpp.

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◆ timerType()

Qt::TimerType QTimer::timerType ( ) const

Definition at line 816 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 244 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 244 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 244 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 244 of file qtimer.h.

◆ 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 244 of file qtimer.h.

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

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

Public Slots

Signals

Public Member Functions

Static Public Member Functions

Protected Member Functions

Properties

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ QTimer()

◆ ~QTimer()

Member Function Documentation

◆ bindableActive()

◆ bindableInterval()

◆ bindableSingleShot()

◆ bindableTimerType()

◆ callOnTimeout()

◆ interval()

◆ isActive()

◆ isSingleShot()

◆ remainingTime()

◆ setInterval()

◆ setSingleShot()

◆ setTimerType()

◆ singleShot() [1/8]

◆ singleShot() [2/8]

◆ singleShot() [3/8]

◆ singleShot() [4/8]

◆ singleShot() [5/8]

◆ singleShot() [6/8]

◆ singleShot() [7/8]

◆ singleShot() [8/8]

◆ start [1/2]

◆ start [2/2]

◆ stop

◆ timeout

◆ timerEvent()

◆ timerId()

◆ timerType()

Property Documentation

◆ active

◆ interval

◆ remainingTime

◆ singleShot

◆ timerType