Qt how to implement a process loop?

Question

I'm beggining with Qt and I'm currently adapting a command-line program to use it with a GUI.

I'm building my GUI like this :

int main(int argc, char *argv[])    
{    
    QApplication a(argc, argv);    
    MainWindow w;    
    w.show();    
    return a.exec();    
}    

I want to process some events permanently. In command line, I used a while loop, it work perfectly. Using Qt, I don't know how I can process these events properly. So I tried to use a std::thread, but my Qt app crashes when I try to modify the GUI from the thread. Same problem using QThread. I don't need threading, so it would be great if I can just put my code in the Qt's main thread.

Anyone can help me please ?

Answer 1

You could use a QTimer connected to a slot in your MainWindow class to run a function periodically like this :

MainWindow::MainWindow()
{
    myTimer = new QTimer();
    myTimer->setSingleShot(false);
    myTimer->start(intervalInMilliseconds);
    connect(myTimer, &QTimer::timeout, this, &MainWindow::handleMyEvents);
}

void MainWindow::handleMyEvents()
{
    // Your code here
}

You could also use threads, but note that you must not call any GUI code from any thread that isn't the QApplication thread, this is probably why your attempt crashed.