Re: [emacs-bidi] Display routines

[Eli Zaretskii]

> From: Michael Welsh Duggan <address@hidden>
> Date: Mon, 05 Nov 2001 21:34:32 -0500
> 
> Would it make good sense to start work on modifying the display
> routines to work with bidirectional text?

That's what I'm doing now.

> A prototype would be based on a embedded-level text property, which
> would have a value consistant with that of UAX#9.

The current design does not call for text properties as the vehicle
for storing the embedding level information.  This information is
computed by the implementation of the UAX#9 algorithm, so it doesn't
make much sense to store it as text properties.  Text properties are
for something that is external to the text, and which cannot be
computed from the text alone.

If I post the description of the design, this will become more
clear.  If not, please ask specific questions later.

> I think this would be a good way to seperate work on the display
> machanism itself from the actual handling of the texts themselves.

My work currently concentrates on the display; I think this is the
first aspect of bidi support that should work.  It doesn't make sense
to do anything else if we cannot even display the text.

However, perhaps it would be useful to have a list of tasks that are
unrelated to display (what you seem to be calling ``the actual
handling of the text'').  Could you suggest a list of these tasks?
That list would probably include Emacs features which need to be
modified to work correctly with bidirectional text, and missing Emacs
features and infrastructure that needs to be added in order to
support bidi.