Re: Adventures in calling Atspi from JavaScript

[Mike Gorse <mgorse alum wpi edu>]

Hi Joseph,

> 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?

> registered = this._atspiEventListener.register_from_callback(
> _atspiCaretCB, 'object:text-caret-moved'

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.

> 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