[XeTeX] longtable and RTL (Arabic)

[Khaled Hosny]

On Tue, Apr 30, 2013 at 01:57:51PM +0100, Arthur Reutenauer wrote:
> > P.S.: Strange enough, the English words "Titel" and "Page" are set
> > correctly LTR without defining a Latin language in the preamble.
> 
>   No, I'm guessing that's an artefact of how XeTeX works: back in the
> times when it was using ICU, it would ship entire words to be shaped,
> and then inserted back into the flow; and the shaping engine knows the
> directionality of the different characters.  Presumably that same
> behaviour has been retained with HarfBuzz; however I'll let Khaled
> comment on that, as I haven't looked at the code.

Yes, no changes here. Each word is processed as a whole, so its
characters are lied out correctly, but inside the line words are
arranged according to eTeX text direction, so if one has more than a
single word, text direction will have to be set explicitly.

Hopefully next year we will have a better model why bidirectional
algorithm is applied to the whole paragraph, but don’t hold your breath.

Regards,
Khaled