internal counters + check sync interval(daily weekly etc) + sync up when out set boundary syncwise.Ive made a little test which prints current time to console, with precision timer it seems accurate and does not drift. Os wise, its linux commandline applications that will be running 24/7 so the time drift is one of my concerns. Right now im more afraid of overdoing this simple task then not getting it to work. I guest the currenttime systemclock version is more "expensive" then internal incrementation of my object and then say once a night check if a diff is building up and then its out of a set range sync it back into range. use a use a precise timer with timeout x ms and increment my clock internally.(this way its allways somewhat in sync with systemclock) use a precise timer with timeout x ms and then grab the currentTime from systemclock to update my internal qdatetime that i use to trigger my signals.also does not go banans after a few days cause of major out of sync with reality/systemtime +- 100ms is hard limit as out of sync as a showstopper.for my use i need a clock that does not trigger early (that means precise timer).So what is the "best" way to get a internal clock? So there is no pre-made internal clock qobject. If you have any problems with the registration process or your account login, please contact us. Registration is fast, simple and absolutely free so please, join our community today! By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. ![]() You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. If you are looking for information about Qt related issue - register and post your question. Over 90 percent of questions asked here gets answered. Qt Centre is a community site devoted to programming in C++ using the Qt framework. Select the forum that you want to visit from the selection below. All other trademarks are property of their respective owners.Before you can post: click the register link above to proceed. Qt and respective logos are trademarks of The Qt Company Ltd. The documentation provided herein is licensed under the terms of the GNU Free Documentation License version 1.3 as published by the Free Software Foundation. The Tetrix example shows how to use QBasicTimer.ĭocumentation contributions included herein are the copyrights of With QBasicTimer, you must reimplement timerEvent() in your QObject subclass and handle the timeout there. If you already have a QObject subclass and want an easy optimization, you can use QBasicTimer instead of QTimer. The normal way of using it is like this:ĪnalogClock ::AnalogClock( QWidget *parent)Ĭonnect(timer, & QTimer ::timeout, this, QOverload ::of( &AnalogClock ::update)) Įvery second, QTimer will call the QWidget::update() slot to refresh the clock's display. That class provides regular timers that emit a signal when the timer fires, and inherits QObject so that it fits well into the ownership structure of most Qt programs. The main API for the timer functionality is QTimer. Windows 2000 has 15 millisecond accuracy other systems that we have tested can handle 1 millisecond intervals. ![]() ![]() The accuracy depends on the underlying operating system. The upper limit for the interval value is determined by the number of milliseconds that can be specified in a signed integer (in practice, this is a period of just over 24 days). Because of this, you must start and stop all timers in the object's thread it is not possible to start timers for objects in another thread. Qt uses the object's thread affinity to determine which thread will deliver the QTimerEvent. To start an event loop from a non-GUI thread, use QThread::exec(). In multithreaded applications, you can use the timer mechanism in any thread that has an event loop. In other words: the accuracy of timers depends on the granularity of your application. This implies that a timer cannot fire while your application is busy doing something else. When a timer fires, the application sends a QTimerEvent, and the flow of control leaves the event loop until the timer event is processed. You start an event loop with QApplication::exec(). The timer will now fire at regular intervals until you explicitly call QObject::killTimer() with the timer ID.įor this mechanism to work, the application must run in an event loop. The function returns a unique integer timer ID. With QObject::startTimer(), you start a timer with an interval in milliseconds as argument. QObject, the base class of all Qt objects, provides the basic timer support in Qt.
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