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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 Analog Clock example):
The following code example is written in c++.
From then on, the update() slot is called every second.
The following code example is written in c++.
From then on, the update() slot is called every second.
The Minnesota Racing qtimer singleshot no such slot Commission supervises the conduct of pari-mutuel betting on horse racing. Enso Sushi Coming Soon Find Your Balance Upgrade your staycation or weekend getaway with an elegant spa treatment. QTimer is very easy to use: create a QTimer, call start to start it and connect its timeout to the appropriate slots. When the time is up it will emit the timeout signal. Note that a QTimer object is destroyed automatically when its parent object is destroyed.
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 the timer's thread affinity to determine which thread will emit the 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: processOneThing() will from then on 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 widgets 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; multithreading is now becoming available on more and more platforms, and we expect that zero-millisecond QTimers will gradually be replaced by QThreads.
Note that QTimer's accuracy depends on the underlying operating system and hardware. Most platforms support an accuracy of 1 millisecond, but Windows 98 supports only 55. If Qt is unable to deliver the requested number of timer clicks, it will silently discard some.
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 to using QTimer is to use
QBasicTimer
. It is typically less cumbersome than using QObject::startTimer()
directly. See 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.
The
QTimer
class provides repetitive and single-shot timers. More…Synopsis¶
Functions¶
- def
interval
() - def
isActive
() - def
isSingleShot
() - def
remainingTime
() - def
setInterval
(msec) - def
setSingleShot
(singleShot) - def
setTimerType
(atype) - def
timerId
() - def
timerType
()
Slots¶
Static functions¶
- def
singleShot
(arg__1, arg__2) - def
singleShot
(msec, receiver, member) - def
singleShot
(msec, timerType, receiver, member)
Detailed Description¶
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 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 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 exec()
. Qt uses the timer’s threadaffinity
to determine which thread will emit the 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: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 QThread
s.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
timertype
. For PreciseTimer
, QTimer
will try to keep the accuracy at 1 millisecond. Precise timers will also never time out earlier than expected.For
CoarseTimer
and VeryCoarseTimer
types, QTimer
may wake up earlier than expected, within the margins for those types: 5% of the interval for CoarseTimer
and 500 ms for 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
timeout()
only once, even if multiple timeouts have expired, and then will resume the original interval.![Shot Shot](/uploads/1/2/6/3/126303232/463922466.png)
Alternatives to QTimer¶
An alternative to using
QTimer
is to call startTimer()
for your object and reimplement the 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 startTimer()
directly. See 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.
See also
QTimer
([parent=None])¶Constructs a timer with the given
parent
.PySide2.QtCore.QTimer.
interval
()¶int
See also
PySide2.QtCore.QTimer.
isActive
()¶bool
Returns
true
if the timer is running (pending); otherwise returns false.PySide2.QtCore.QTimer.
isSingleShot
()¶bool
PySide2.QtCore.QTimer.
remainingTime
()¶int
PySide2.QtCore.QTimer.
setInterval
(msec)¶msec –
int
PySide2.QtCore.QTimer.
setSingleShot
(singleShot)¶singleShot –
bool
See also
PySide2.QtCore.QTimer.
setTimerType
(atype)¶Qtimer Singleshot No Such Slot Game
atype –
TimerType
PySide2.QtCore.QTimer.
singleShot
(arg__1, arg__2)¶- arg__1 –
int
- arg__2 –
PyCallable
PySide2.QtCore.QTimer.
singleShot
(msec, timerType, receiver, member)- msec –
int
- timerType –
TimerType
- receiver –
QObject
- member – str
This is an overloaded function.
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
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
PySide2.QtCore.QTimer.
singleShot
(msec, receiver, member)- msec –
int
- receiver –
QObject
- member – str
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
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
PySide2.QtCore.QTimer.
start
()¶This function overloads .
Starts or restarts the timer with the timeout specified in
interval
.If the timer is already running, it will be
stopped
and restarted.If
singleShot
is true, the timer will be activated only once.Qtimer Stop
PySide2.QtCore.QTimer.
start
(msec)msec –
int
Starts or restarts the timer with a timeout interval of
msec
milliseconds.If the timer is already running, it will be
stopped
and restarted.If
singleShot
is true, the timer will be activated only once.PySide2.QtCore.QTimer.
stop
()¶Stops the timer.
PySide2.QtCore.QTimer.
timerId
()¶int
Returns the ID of the timer if the timer is running; otherwise returns -1.
PySide2.QtCore.QTimer.
timerType
()¶Qtimer Singleshot Parameter
TimerType
Qtimer Singleshot No Such Slot Machine
See also
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