Re: Adventures in calling Atspi from JavaScript

[Joseph Scheuhammer <clown alum mit edu>]

Hi Mike,

Thanks for your suggestions -- it improved things a bit.  See below.

> > 1. Registering 'object:text-caret-moved' always results in an error.
> >
> > The actual error is garbled, containing non-printable characters. 
> > Here is what I get:
> >
> > > Window manager warning: Log level 16: Atspi: Adding match: 
> > Interface name
> > > 'org.a11y.atspi.Event.object' is invalid.
>
> This is strange; I'm not seeing anything obvious when looking at the 
> code, and I can't reproduce it. Does valgrind show any invalid reads 
> or writes?

I'm not familiar with valgrind.  How do I use it?  Perhaps after 
tomorrow's a11y meeting we can discuss in #a11y, if you have the time?

> > _atspiCaretCB, 'object:text-caret-moved'
> registered = this._atspiEventListener.register_from_callback(
>
> This won't work in a way that can be deregistered, however. See below.
>
> > When deregister_from_callback() is called, the return value is 
> > 'true', suggesting that the event has been deregistered. However, the 
> > callback that was supplied during the prior register_from_callback() 
> > is still invoked. It's as if the system is saying, "Okay, you've been 
> > disconnected as requested", but nonetheless keeps calling back when 
> > the event occurs.
>
> It is a bug that it is returning TRUE when it didn't find anything to 
> deregister. I'll need to fix that.

Hey, I found a bug :-).

> > The way it's deregistered:
> > deregistered = this._atspiEventListener.deregister_from_callback(
> > _atspiFocusCB, 'object:state-changed:focused'
>
> Atspi_event_listener_register_from_callback and 
> deregister_from_callback are convenience functions intended to avoid 
> needing to create an AtspiEventListener. The scope annotations on 
> those functions are incorrect. Changing the scope to "notify" and 
> adding a GDestroyNotify callback might work, although that would mean 
> an API break. Anyway, gjs is creating a wrapper around the callback 
> when it is called, so libatspi sees a different pointer for the 
> deregister call than it saw for the register call, so it does not make 
> a match.
> Doing something like the following works for me, though:
> function cb(e)
> {
>   print(e)
> }
>
> l = Atspi.EventListener.new(cb)
> registered = l.register('object:text-caret-moved')
> l.deregister('object:text-caret-moved')
>
> Hth,
> -Mike

I modified my code to match you suggestion above.  It solves the 
registering/deregistering problem.  But, I get the same error when 
registering 'object:text-caret-moved'.  And, I still get the same delay 
when moving focus to an St widget.

I'll be in touch tomorrow.

--
;;;;joseph.


'A: After all, it isn't rocket science.'
'K: Right. It's merely computer science.'
             - J. D. Klaun -