Re: [emacs-bidi] Re: emacs-bidi - funtional/ready, now what ?

[Alex Schroeder <alex at emacswiki dot org>]

TAKAHASHI Naoto <ntakahas at m17n dot org> writes:

> I do not think any URL is available for now.  If someone writes a
> summary, I can put it one the emacs-bidi web page.

At the time the problem was this:  The display engine moves through
the buffer character by character and decides how to display it.  This
is the current architecture, and the display engine is a very delicate
piece of work, so this is not going to change unless somebody rewrites
alot of code.

Therefore, we cannot use existing bidi algorithms, because these
expect a string instead of a stream of characters.  Using a string,
one could implement the Unicode or a similar reordering algorithm
which returned a "visual order" string to display.  But this
straightforward route is not acceptable if we want to integrate bidi
at the display engine level.

We need a piece of code that hooks into the display engine and that
can return the next character to display, given a position in a
buffer.  (The important part here is that this will probably not be
the character at that position when bidi reordering is in effect.)
This will require looking ahead, looking behind, applying algorithms,
and caching the result, so that when the display engine moves to the
next position in the buffer and wants to know what character to
display, less work is required.

Anyway, that's the basic problem description.

It seems that Eli has a stand-alone solution of this piece of code and
needs to integrate it into the display engine.  That is hairy work.
If you are interested, ask Eli -- last time he was very willing to
send his code to parties interested in helping out.

Nadim Shaikli writes:

>> With most people short on time being the norm - is there a document or
>> a set of people with enough acumen that can put all those thoughts and
>> pointers into a document for someone to pick up ?

I am trying to collect things on the wiki...
http://www.emacswiki.org/cgi-bin/wiki.pl?CategoryBidi

But you'd have to pose specific questions (like the one above) so that
I can write things up if I know anything.

> Yes, there are a few men who satisfy 1. and 2. above, but they are all
> busy.  (You know how such people are rare and precious.)  If you
> really want bidi support right now, you need to hire them.  Otherwise,
> you need to wait for their voluntary work or do it yourself.

Perhaps we can collect some money -- but we wouldn't be able to
collect more than a few hundred dollars, which usually doesn't pay for
more than a few hours of coding (at least here in Switzerland)...  :)
But if you know somebody who is willing to do it for $300 or $500, I
might investigate this further.

> We keep adding new features to emacs-bidi.  Once GNU Emacs is equipped
> with bidi support, we will port functionalities and interfaces
> developed on emacs-bidi.

Yay!  :)

Alex.