[SOLVED] Execute code every X seconds (X not constant)

BlackMamba

Hello,

I have a vector which contains some time values like 0, 1.34, 4.56, etc ... which are not regular.
I want to be able to execute some code for all these time values.
The first idea I had was to use a QTimer but how? Because QTimer looks more useful when you need to execute code every fixed time interval with timeout() signal.

Thanks for your help,

raven-worx

is "QTimer::singleShot()":http://qt-project.org/doc/qt-4.8/qtimer.html#singleShot what you are looking for?

BlackMamba

If I use a QTimer, yes it will need to be singleshot but it is not enough to solve my issue.
Lets say I do timer->start();
Then how do I parse my vector in real time to know if I need to execute the code?
@QTimer* timer = new QTimer;
timer->setSingleShot(true);
timer->start();
for(int i=0;i<myvector.size();i++){
if(timer->ellapsed()=myvector[i]{
// execute code
}
}@

This looks to be very awkward and I dont know if the "=" in
@if(timer->ellapsed()=myvector[i] @

is working ...

raven-worx

QTimer::singelShot() is a static method. So you don't need a QTimer instance and thus also not call start().
The slot you specify will be executed once on timeout.

BlackMamba

Yes but how does this solve my issue?
I would like to have kind of timeout but at irregular interval ...

raven-worx

for example:
@
void MyExecuteSlot()
{
//DO SOME WORK

if( values.count() )   //values is of type QList?
    QTimer::singleShot( values.takeFirst() * 1000, this, SLOT(MyExecuteSlot()) );

}
@

I assumed your values are in seconds? (QTimer only accepts milliseconds).

Please note: I don't know on which OS you are working on, but you will only receive an approximate real time speed on a non realtime OS.

BlackMamba

It looks nice I will try this tonight . I am working on windows. I don't need real time OS, how accurate this timer will be? If the latence is like 10ms, its fine !
I have a std::vector instead of a QList but you gave me the logic !
I knew the ravens were very smart ;)

Thanks

mehrdadsilver

and you can use setTimerType(Qt::PreciseTimer) for better accuracy if you want to use QTimer object (No Static singleshot). after each interval restart timer with next value.

NicuPopescu

good to know you're working on windows ... so you could have a time resolution of nanoseconds ... and I think in this case qint64 QElapsedTimer::nsecsElapsed () const could be used

bq. if(timer->ellapsed()=myvector[i]{
// execute code
}
}

QTimer even has no ellapsed method

on the other hand, I think QTimerEvent or QBasicTimer are lighter/faster than QTimer using signals; anyway all of them provide control just in milliseconds, compared with QElapsedTimer which can work with much higher resolution

see also QElapsedTimer::ClockType for windows

Cheers!