Question

I’m making a simple game with Qt and I’d like to pause the game when the user switches to a different window (this could be by minimizing it or by accidentally clicking on a window beside it, etc). My game is wrapped in a QMainWindow, so I’d like to be able to detect when that loses focus.

I’ve tried a few different methods for this, but I haven’t been successful. I first tried overloading QMainWindow’s focusOutEvent, but this method was only called when I first gave the window focus with setFocus. I also tried to overload the window’s event(QEvent *) method to check for QEvent::ApplicationActive and QEvent::ApplicationDeactivate.

I would post the code for my QMainWindow but there isn’t much to show, I literally just tried to implement those two methods but neither were called. I did nothing else to set up those methods (maybe I’m missing a step?).

Does anyone know a good way to determine if your QMainWindow has “lost focus”?

Answer 1

I had a similar need once, and resolved it by overloading event(QEvent*) method of my QMainWindow :

bool MyMainWindow::event(QEvent * e)
{
    switch(e->type())
    {
        // ...

        case QEvent::WindowActivate :
            // gained focus
            break ;

        case QEvent::WindowDeactivate :
            // lost focus
            break ;
        // ...
    } ;
    return QMainWindow::event(e) ;
}