QBasicTimer Class

The QBasicTimer class provides timer events for objects. More...

Header: #include <QBasicTimer>
qmake: QT += core

Public Functions

QBasicTimer(QBasicTimer &&other)
QBasicTimer()
QBasicTimer &operator=(QBasicTimer &&other)
~QBasicTimer()
bool isActive() const
void start(int msec, QObject *object)
void start(int msec, Qt::TimerType timerType, QObject *obj)
void stop()
void swap(QBasicTimer &other)
int timerId() const

Detailed Description

This is a fast, lightweight, and low-level class used by Qt internally. We recommend using the higher-level QTimer class rather than this class if you want to use timers in your applications. Note that this timer is a repeating timer that will send subsequent timer events unless the stop() function is called.

To use this class, create a QBasicTimer, and call its start() function with a timeout interval and with a pointer to a QObject subclass. When the timer times out it will send a timer event to the QObject subclass. The timer can be stopped at any time using stop(). isActive() returns true for a timer that is running; i.e. it has been started, has not reached the timeout time, and has not been stopped. The timer's ID can be retrieved using timerId().

Objects of this class cannot be copied, but can be moved, so you can maintain a list of basic timers by holding them in container that supports move-only types, e.g. std::vector.

The Wiggly example uses QBasicTimer to repaint a widget at regular intervals.

See also QTimer, QTimerEvent, QObject::timerEvent(), Timers, and Wiggly Example.

Member Function Documentation

QBasicTimer::QBasicTimer(QBasicTimer &&other)

Move-constructs a basic timer from other, which is left inactive.

This function was introduced in Qt 5.14.

See also isActive() and swap().

QBasicTimer::QBasicTimer()

Contructs a basic timer.

See also start().

QBasicTimer &QBasicTimer::operator=(QBasicTimer &&other)

Move-assigns other to this basic timer. The timer previously represented by this basic timer is stopped. other is left as inactive.

This function was introduced in Qt 5.14.

See also stop(), isActive(), and swap().

QBasicTimer::~QBasicTimer()

Destroys the basic timer.

bool QBasicTimer::isActive() const

Returns true if the timer is running and has not been stopped; otherwise returns false.

See also start() and stop().

void QBasicTimer::start(int msec, QObject *object)

Starts (or restarts) the timer with a msec milliseconds timeout. The timer will be a Qt::CoarseTimer. See Qt::TimerType for information on the different timer types.

The given object will receive timer events.

See also stop(), isActive(), QObject::timerEvent(), and Qt::CoarseTimer.

void QBasicTimer::start(int msec, Qt::TimerType timerType, QObject *obj)

This is an overloaded function.

Starts (or restarts) the timer with a msec milliseconds timeout and the given timerType. See Qt::TimerType for information on the different timer types.

obj will receive timer events.

See also stop(), isActive(), QObject::timerEvent(), and Qt::TimerType.

void QBasicTimer::stop()

Stops the timer.

See also start() and isActive().

int QBasicTimer::timerId() const

Returns the timer's ID.

See also QTimerEvent::timerId().

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