Timers

QObject, the base class of all Qt objects, provides the basic timer support in Qt. With QObject::startTimer(), you start a timer with an interval in milliseconds as argument. The function returns a unique integer timer ID. The timer will now fire at regular intervals until you explicitly call QObject::killTimer() with the timer ID.

For this mechanism to work, the application must run in an event loop. You start an event loop with QApplication::exec(). When a timer fires, the application sends a QTimerEvent, and the flow of control leaves the event loop until the timer event is processed. This implies that a timer cannot fire while your application is busy doing something else. In other words: the accuracy of timers depends on the granularity of your application.

In multithreaded applications, you can use the timer mechanism in any thread that has an event