QTimer::singleShot - forward parameter to SLOT called | Qt Forum
See Timers for an overview of all three approaches.
Because of this, you must start and stop the timer in its thread; it is not possible to start a timer from another thread. 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 QThread s.
The function returns a unique integer timer ID. 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.
To use it, create a QTimerconnect its timeout signal to the appropriate slots, and call start. 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.
The 3 slot power cord best buy Clock example shows how to use QTimer to redraw a widget at regular intervals.
Timer events will be delivered only while the event loop is running.
The disadvantage is that timerEvent does not support such high-level features as single-shot timers or signals. 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 GUI programs.
The accuracy of timers depends on the underlying operating system and hardware. Qt uses the object's thread affinity to determine which thread will deliver the QTimerEvent.
From then on it will emit the timeout signal at constant intervals. Because of this, you must start and stop the timer in its thread; it is not possible to start a timer from another thread.
You can set a timer to time out only once by calling setSingleShot true. Example for a one second millisecond timer from the Analog Clock example: Qt uses the timer's thread affinity to determine which thread will emit the timeout signal.
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.
If Qt is unable to deliver the requested number of timer clicks, it will silently discard some. Documentation contributions qtimer slot argument herein are the copyrights of their respective owners. This implies that a timer cannot fire while your application is busy doing something else.
Qt uses the timer's thread affinity to determine which thread will emit the timeout signal. The QTimer class provides a high-level programming interface for timers. Next, its timeout signal is connected to the slot that will do the work, it is started with a value of milliseconds, indicating that it will time out every second.
In multithreaded applications, you can use the timer mechanism in any thread that has an event loop. 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 can be used to do heavy work qtimer slot argument providing a snappy user interface: QTimer also provides a static function for single-shot timers. All other trademarks are property of their respective owners.
Most platforms support a resolution of 1 millisecond, though the accuracy of the timer will not equal this resolution in many real-world situations. Qt and respective logos are trademarks of The Qt Company Ltd.
The normal way of using it is like this: The accuracy depends on the underlying operating system. When a timer fires, the application sends a QTimerEventand the flow of control leaves the event loop until the timer event is processed. For QTimer to work, you must have an event loop in your application; that is, you must call QCoreApplication:: You can also use the static QTimer:: It is typically less cumbersome than using QObject:: The Wiggly example shows how to use QBasicTimer.
Windows has 15 millisecond accuracy; other systems that we have tested can handle 1 millisecond intervals. Accuracy and Timer Resolution Timers will never time out earlier than the specified timeout value and they are not guaranteed to time out at the exact value specified.
You start an event loop with QApplication:: In multithreaded applications, you can use QTimer in any thread that has an event loop. In many situations, they may time out late by a period of time that depends on the accuracy of the casino night rentals mn timers.
The timer will now fire at regular intervals until you explicitly call QObject:: Some operating systems limit the number of timers that may be used; Qt tries to work around these limitations.