Qtimer Signal Slot
In QT5, we have a special timer class, QTimer. We can use it to complete some timing operations. Examples are as follows:
The signal timeout emitted from main thread, As timer and worker live in different threads, their connection type is queued connection. The slot get called in its living thread, which is the sub-thread. Thanks to a mechanism called queued connections, it is safe to connect signals and slots across different threads. The timer triggers the timeout signal when the time is over and this will be called in the main-event loop. QTimer::singleShot simple usage. The QTimer::singleShot is used to call a slot/lambda asynchronously after n ms. The basic syntax is: QTimer::singleShot(myTime, myObject, SLOT(myMethodInMyObject)). QTimer; Basic Usage; QTimer::singleShot simple usage; Simple example; Singleshot Timer with Lambda function as slot; Using QTimer to run code on main thread; Signals and Slots; SQL on Qt; Threading and Concurrency; Using Style Sheets Effectively. Next, its timeout signal is connected to the slot that will do the work, it is started with a value of 1000 milliseconds, indicating that it will time out every second. QTimer also provides a static function for single-shot timers. QTimer timeout signal not invoking slot when run on a different thread. Pass pointer to itself in emit in Qt. When or how to delete QThread in Qt.
At the end of our timer, we need to stop the timer manually, otherwise it will send out the timeout signal continuously. At the same time, we need to note that before making the connection function, we need to have an instance of the timer, otherwise it will cause the program to crash. Of course, we can use the static method of QTimer instead of instantiating the timer to start the timer directly Here is an example of a QT document:
We can use multiple timers in a program. Each timer has its own timer ID, which is similar to the pid of window process. We can use timer event to process multiple timers
reference resources: QTimer timer
The idea of program design is as follows
Qt Qtimer Signal Slot
- Set the timing period first
- Bind the timeout() signal to the custom slot function
- Call the start function to start the timer
The following is the definition in the widget window class:
In this paper, a QTimer is defined, and the slot function onTimeOut() is defined as the slot function corresponding to the timeout signal.
The code in the constructor of the window class is as follows:
In this example, the timing period of the timer is set to 1s, then the signal is bound to the slot, and finally the timer is started.
Qtimer Signal Slot Car
The code in the timer processing function is as follows:
Qtimer Signal Slot Example
reference resources: Qtimer of Qt