# [luatex] Fribidi for LuaTeX

Taco Hoekwater taco at elvenkind.com
Mon Jul 25 09:10:13 CEST 2011

```Hi,

On 07/24/2011 07:48 PM, Khaled Hosny wrote:
> 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),
>> * out-of-line tokens (like alignment templates and macro expansions),
>> * vertical typesetting,
>> * TeX grouping levels,
>> * Interfering nodes (math, \special, \rule etc)
>
> Some questions from me:
>
> * local_par whatsit:
>    - it is always the 1st node in the list (if exists at all), right?

yes, it is and should remain the first node.

>    - \textdir inserts begindir node after it, is this a general rule?

yes

>    - what is the dir field is used for? I can query it but setting it (to
>      TRT for example) has no effect (the par still left aligned).

That could be a timing problem in the change, but I need a test file to
debug.

> * when \pardir is set to TRT while \textdir is still TLT luatex will
>    enclose the paragraph with begindir/enddir TLT nodes (skipping the
>    local_par etc.), right? if yes, is there anyway to suppress this?

There is no way to suppress that, but it should not have ignored
local_par, I think. Again a test file would be helpful.

> * how can I set paragraph direction to TRT without setting \pardir,
>    in pre_linebreak_filter?