Issue while detecting the Focus status of my Application

CLBSII

Hi everyone,

I'm looking for a way to detect when my application is put in the background (for example after the user uses alt-tab).

After some researchs, I figure out that the best way to do it is to use the focus functionality since my application in based on a QMainWindow class.

So I set up the FocusPolicy as follow in my class definition function:

MainWindow::setFocusPolicy(Qt::StrongFocus);

When the program is running, I have a testing sequence that regularly check if my application has focus with

qDebug() << MainWindow::hasFocus();

And whatever I do (casually use my application, do atl-tab and use another ...). The focus return me false every time.

I assume that I'm missing some point, but I can't find what. Any suggestions ?

Thank you !

mpergand

Hi,

There's a signal in QApplication that should meet your needs:

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    
    QObject::connect(&app,&QApplication::applicationStateChanged,[](Qt::ApplicationState state)
        {
        qDebug()<<state;
        });

    return app.exec();
}

In your MainWindow's constructor, you can do:

connect(qApp,&QApplication::applicationStateChanged,[] (Qt::ApplicationState state)
        {
        qDebug()<<state;
        });

CLBSII

Indeed it seems to work properly, thank you very much !