Re: [orca-list] Firefox caching

[Isaac Porat <isaac porat me uk>]

Hi Joanie

I have started this thread asking about caching as a means of increasing 
performance.  To my mind, the issue of presentation is a separate one 
and while the discussion was interesting this is not what I had in mind.

Does Orca cache the DOM (Document Object Model).  I understand that 
Gecko has facilities for signalling the access technology of partial 
update of the DOM cache and I am curious if possible to know briefly  
how Orca is using these techniques.

Thanks
Isaac

On 13/09/2010 09:21, Joanmarie Diggs wrote:
> Hi Michael, all.
>
>    
> > So can I just check, does this mean orca will still directly access the
> > page
> >      
> Correct.
>
>    
> >   rather than virtual buffers (or whatever you want to call it),
> >      
> Correct.
>
>    
> > but just offer an additional layout mode?
> >      
> More or less, yes. Basically, due to Gecko's native caret navigation
> being broken, Orca has had to implement its own version. That requires
> that we decide things like:
>
> 1. Where do lines start and end?
> 2. What is the content of a line?
> 3. What should we present when a line is moved to?
>
> In other words, Orca already is defining "line" by looking at the text
> (for new lines), by looking at character extents (to see if spatially
> character 1 and character 2 are on the same line), and so on. All we
> need to do is add an option which causes lines to also be defined by the
> start or end of a link. It's really pretty trivial.
>
>    
> > I would have to say that the direct access to the page seems to work far
> > better than my experience with windows screen readers using virtual
> > buffers (many of the reasons given, the main one being how orca handles
> > dynamically changed pages) and so I would not like to see the current
> > behaviour of orca change.
> >      
> We have no plans to change that behavior -- other than make the
> experience more performant, and provide an option (which users will have
> to explicitly enable) to present one link per line.
>
>    
> > If there's a demand for a given presentation then why not have it
> > as an option particularly if it won't affect your preferred presentation?
> >      
> I agree.
>
>    
> > Regarding performance of orca and firefox, I wonder if some of the
> > problem really comes from some of the work arounds and checking has to
> > do because of firefox issues.
> >      
> I'd bet money on it, having put many of those work-arounds in place
> myself. There is a *bunch* of special casing. What I'm hoping to have
> time to do before long is revisit those various work-arounds to
> ascertain if they are indeed still needed.
>
> Take care.
> --joanie
>
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