event filter not called before menu shortcut dispatch

davecotter

in my QApplication i have a key-down filter:

class QKJams : public QApplication {
	typedef QApplication _inherited;
	public:

	QKJams(int argc, char *argv[]) :
		_inherited(argc, argv)
	{
		installEventFilter(this);
	}

	bool	event(QEvent *eventP)
	{
		QEvent::Type	eventType(eventP->type());
		
		switch (eventType) {
			
			case QEvent::KeyPress: {
• <-- breakpoint  handledB = _inherited::event(eventP);
			} break;
		}
		return handledB;
	}

	bool	eventFilter(QObject *objP, QEvent *eventP)
	{
		bool			handledB = false;

		switch (eventP->type()) {
			case QEvent::KeyPress: {
• <-- breakpoint  handledB = _inherited::eventFilter(objP, eventP);
			} break;
		}
		return handledB;
	}
};

yet keyboard shortcuts are sent to the menu handler BEFORE the app either filters OR handles the event. the breakpoints above are not hit when i press a key that happens to be an unmodified shortcut key in the menu bar.

the doc says the App should get a crack at the event BEFORE any other processing, which i took to mean before looking in the menu bar for a matching key shortcut.

davecotter

update: only if i remove the key shortcut from the menu, then it works, but backwards from what i thought it should do: first the Window filter get called, then the App filter. i thought the App filter would get called FIRST, then window, then menubar?

Axel Spoerl

@davecotter said in event filter not called before menu shortcut dispatch:

first the Window filter get called

Hi David,
Unless I have missed something here: I don’t find that “Window filter” in the code.
Cheers
Axel

davecotter

well i didn't post the full project. but it is there, trust me.

my question is: is it expected that it goes: menus, windows, app ? and not the other way around?

Pl45m4

@davecotter

Hi, you say it stops working when you add the menu shortcut?!
what's the context of your menu shortcut?

https://doc.qt.io/qt-6/qt.html#ShortcutContext-enum

and not the other way around?

Propagation in the QObject tree is bottom up, starting with the "inner-most" child at event "position".

If you want to handle the same application-wide shortcut with your menu, try to set it to Qt::ApplicationShortcut otherwise the Qt::WindowShortcut from your menu in your Window will accept and eat the key/shortcut event and it will never reach your application handler...
There is an article in the Qt Documentation about shortcut contexts and ambiguity... can't find it right now.

Btw:

@davecotter said in event filter not called before menu shortcut dispatch:

  installEventFilter(this);

This line, which is short for this->installEventFilter(this); doesn't make too much sense :)
A QObject doesn't need an eventFilter to watch its own events, it will receive and handle them anyway using QObject::event() and all the more specific event handlers (like QWidget::mouseMoveEvent or key-press-Events... etc.).

JonB

@davecotter
As @Pl45m4 has written, events go to the "most specific, innermost" widget first. If that handles/accepts the event that's it; if it does not/rejects then the next outer widget gets to have a go, and so on up the hierarchy tree. If you define something like an ApplicationShortcut that by-passes the usual handling and goes straight to that handler.

davecotter

so are menu bar keyboard shortcuts considered the "most specific" ?

davecotter

I guess that's my question 👆🏻

Pl45m4

@davecotter

and that 👉 https://forum.qt.io/post/808209 is my answer.
Have you tried it? Does it work?