Re: [emacs-bidi] Bidi - will it happen ?

[Eli Zaretskii]

On Sat, 15 Jun 2002, Tim Freedom wrote:

> I'm at a loss here, why is it that qemacs
> 
>   http://fabrice.bellard.free.fr/qemacs
> 
> has been able to include bidi where-as emacs hasn't ?

There's nothing in principle that should prevent Emacs from supporting 
bidirectional editing, except that no one has stepped forward and 
volunteered to do the job.  I'm trying to do that by default, but my 
resources are in short supply lately.

> I know nothing of lisp (let alone elisp), but can't
> the inclusion of fribidi (fribidi.sf.net) be
> incorporated somehow into the emacs code even as an
> external call for the time being (irrespective of
> inefficiency, ugliness, etc - given the user opts for
> its inclusion) ?

We cannot use fribidi (or any other library that requires Emacs to pass 
it a chunk of text to be displayed) because that is incompatible with how 
the Emacsd display engine works.  I explained that several times here; 
you should be able to find the explanation in the archives.

> There is a major disconnect on this topic if one were
> to do any research on it (emacs+bidi that this) on
> google or anywhere else.  m17n.org had claimed that 
> bidi is close at hand (through its various symposiums).
> Can't the various interests (m17n, emacs, xemacs, utf2000,
> etc) unite and have one highly concentrated effort to get
> this done with ?  Bidi's status is very nebulous at best.

The principles of bidi support and the general idea how to do it are 
clear.  What is needed is motivated individuals who wouldn't hesitate to 
study the Emacs display engine code, then hack it to include the 
bidirectional support.  I'll be more than happy to help such individuals 
and pass to them what I've written so far; but first I need to see them 
volunteer and start working seriously.

In other words, the problem is not the design; the problem is coding 
(lots of it).  And since the first phase of that coding is to modify the 
display engine, a person who wants to work on this will have to get a 
fairly good understanding of how the display works in Emacs.

> Can we start anew with clear indications of what has
> or hasn't been done and what is needed to complete the
> job

I believe there's enough about this in the archives of this list.  Please 
ask specific questions if something there is unclear or incomplete.