[luatex] Fribidi for LuaTeX

[Khaled Hosny]

On Tue, Jul 12, 2011 at 03:51:24PM +0200, Taco Hoekwater wrote:
> 
> Hi,
> 
> Now that the Unicode BiDi algorithm implementation discussion
> seems to restart, it is a good time to ask the people involved
> to solve the non-trivial problem of adjusting the algorithm
> to cater for the inclusion of
> 
> * out-of-line node objects (\setbox, \box, \copy),

Each box would be treated as a single paragraph.

> * out-of-line tokens (like alignment templates and macro expansions),
> * vertical typesetting,
No idea about those two.

> * TeX grouping levels,

It can be used to simulate BiDi embedding, e.g: {latin ARABIC} would be
equivalent to [LRE]latin ARABIC[PDF] but this can lead to many undesired
effect, e.g. "ARABIC {\emp latin!}" get rendered as "latin! CIBARA"
while it should have been "!latin CIBARA", so in general it is better to
ignore TeX grouping or it least be configurable and off by default.

> * Interfering nodes (math, \special, \rule etc)

They should be given neutral bidi class so to inherit the directionality
of its surroundings, and the contents (if textual) be handled as
separate paragraphs. Math is kinda special and needs special work as
whether right-to-left math is needed or not.

Regards,
 Khaled

-- 
 Khaled Hosny
 Egyptian
 Arab