App Icon notification behaviour with respect to focus-in and focus-out of the application

[SGaist]

Hi,

You'll likely be interested by QGuiApplication:: applicationStateChanged and the Qt::ApplicationState enumeration.

[gully]

@SGaist said in App Icon notification behaviour with respect to focus-in and focus-out of the application:

QGuiApplication:: applicationStateChanged

I am using QApplication, is it anyways possible with QApplication?

[mrjj]

@gully
Hi
Since its
class Q_WIDGETS_EXPORT QApplication : public QGuiApplication

it should be possible ?

[gully]

QApplication a(argc, argv);
    livewindow window;

    QApplication::connect(a, SIGNAL(applicationStateChanged(Qt::ApplicationState state)),window, SLOT(appstate(Qt::ApplicationState state)));

This is what I am doing..but getting an error..What would be the right way to do this?

[mrjj]

@gully
Well, first of all, always show the actual error :)
in this case i think you need

QObject::connect(&a, SIGNAL(applicationStateChanged(Qt::ApplicationState state)),window, SLOT(appstate(Qt::ApplicationState state))); // dont include varname, only type

[gully]

@mrjj said in App Icon notification behaviour with respect to focus-in and focus-out of the application:

QObject::connect(&a, SIGNAL(applicationStateChanged(Qt::ApplicationState state)),window, SLOT(appstate(Qt::ApplicationState state)));

Now I am getting

error: no matching function for call to 'connect'
QObject::connect(&a, SIGNAL(applicationStateChanged(Qt::ApplicationState)),window, SLOT(appstate(Qt::ApplicationState)));
^~~~~~~~~~~~~~~~

[mrjj]

Hmm
let me try
is window , a normal MainWindow in main, or where do you do it ?

[mrjj]

Hi
Tried.

int main(int argc, char* argv[]) {
  QApplication a(argc, argv);
  MainWindow w;
  w.show();
  qDebug() << "works" << QObject::connect(&a, SIGNAL(applicationStateChanged(Qt::ApplicationState)), &w, SLOT(appstate(Qt::ApplicationState)));
  return a.exec();
}

return true so seems to like it.

in mainwindow , i have

public slots:
    void appstate(Qt::ApplicationState) {}

update:
i also put qDebug() in appstate
and it fires/works.

[gully]

Thanx a lot..yeeah its working now... But I wonder what I was doing wrong?

[mrjj]

@gully
my best guess is you forgot & if the objects you connect is not pointers.
Like MainWindow in main.cpp.
so it was &window but not sure if pointer or not.

[gully]

Thanks a ton for pointing it out.Yes indeed that is what I missed out.

[mrjj]

@gully
Just as a note.
Unless in main.cpp , if you need to use & for a connect, check that the object wont run out of
scope and be deleted when function ends.
In main.cpp, the "return a.exec();" blocks and it wont run out of scope.
But in other places, having to use & should raise a flag in head so check the objects in the
connect. (should be pointers in most places)