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Qtimer Signal Slot
Few talk about the use of class QTimer in Qt. This is a small lightweight theme after a series of articles about QSqlTabelModel volume and the resulting consequences of it.
The QTimer class provides repetitive and single-shot timers. The QTimer class provides a high-level programming interface for timers. To use it, create a QTimer, connect its timeout signal to the appropriate slots, and call start. From then on it will emit the timeout signal at constant intervals. 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.
Qtimer Signal Slot Example
Timers we may need to create a poll LAN devices via TCP / IP stack with certain intervals or hourly data validation or active connections to the server. Yes to anything !? And here we come to the aid QTimer, which we consider the example of output every second time QLabel.
Project structure
We use a minimum of files in our project:
- QDataMapperWidget.pro
- mainwindow.h - header file of the main application window;
- mainwindow.cpp -source window;
- main.cpp - the main source file from which the application starts;
- mainwindow.ui - form of the main application window;
A draw form in the Designer Qt Creator. But there is nothing to draw. QLabel thrown into the middle and ready.
mainwindow.h
All we need to be happy in this project - a slot that will respond to the operation of a QTimer, but the object of this class.
mainwindow.cpp
And now a few lines to launch the timer. In my comments more than code. Usually so on Assembler`e write - 20% and 80% of the code comments.
Conclusion
Qtimer Signal Slot Machine
As a result, when you start to discover how every moment in time is changing us in the application window