QT on OS X, how to detect clicking the app Dock Icon

Question

I have an open Qt Mac app. I am clicking the app Icon

Is there a way to get a notification for this in the app?

Answer 1

The problem with QEvent::ApplicationActivate is that it will be emitted for every activation - eg., even if you switch to the app on Application Switcher. The native behavior is to show the app only on Dock icon click, not when you are switching by cmd+tab.

But, there is a hack that works at least for Qt 5.9.1. The Dock icon click produces 2 sequential QEvent::ApplicationStateChangeEvent events, meanwhile cmd+tab - only one. So, this code will emit Dock click signal quite accurately. App class is the application class inherited from QApplication and also an event filter for itself.

bool App::eventFilter(QObject* watched, QEvent* event)
{
#ifdef Q_OS_MACOS
    if (watched == this && event->type() == QEvent::ApplicationStateChange) {
        auto ev = static_cast(event);
        if (_prevAppState == Qt::ApplicationActive
                && ev->applicationState() == Qt::ApplicationActive) {
            emit clickedOnDock();
        }
        _prevAppState = ev->applicationState();
    }
#endif // Q_OS_MACOS
    return QApplication::eventFilter(watched, event);
}