How to detect if a Qt GUI application has been idle, inside the app itself (Qt)?

Question

How to detect when a GUI application has been idle, (ie, no user interaction), for a period of time ?

I have n number of Qt Screens , I want to bring Date-Time scree

Answer 1

According to QT Documentation :

To make your application perform idle processing (i.e. executing a special function whenever there are no pending events), use a QTimer with 0 timeout. More advanced idle processing schemes can be achieved using processEvents().

So you need to create a QTimer with zero timeout interval and connect it to your slot that is called when application is idle.

Answer 2

Override QCoreApplication::notify and a timer on mouse/keyboard events?

(Or just store the time of the event and have a timer check that value periodically, which might be faster than resetting a timer all the time.)

class QMyApplication : public QApplication
{
public:
    QTimer m_timer;

    QMyApplication() {
        m_timer.setInterval(5000);
        connect(&m_timer, SIGNAL(timeout()), this, SLOT(app_idle_for_five_secs());
        m_timer.start();
    }
slots:
    bool app_idle_for_five_secs() {
        m_timer.stop();
        // ...
    }
protected:
    bool QMyApplication::notify ( QObject * receiver, QEvent * event )
    {
        if (event->type == QEvent::MouseMove || event->type == QEvent::KeyPress) {
             m_timer.stop(); // reset timer
             m_timer.start();
        }    
        return QApplicaiton::notify(receiver, event);
    }
};