[XeTeX] Issue with Arabic Typography

[Gareth Hughes]

وفا خلیقی wrote:
>     This bug is related to the difference between Persian and English in
> adjusting the end of lines. In English, for stretching a line, some spaces
> (glue) are added between the words. In Persian, however, some letters inside
> the words are stretched (what is called in Persian calligraphy a
> "KESHIDEH"). Adding spaces between words to adjust a Persian line produces
> less beautiful documents (and I guess that for this reason you have disabled
> it in XePersian). However, the "Keshideh" system does not exist in
> XePersian. (In MS-Word this system existed even in its very old versions on
> Win3.1, and without implementing it in FarsiTeX, the output was less
> beautiful even than those old MS-Word outputs).

I believe that this is very important not only for Persian, but for all
Arabic-Persian scripts and Syriac as well. In all these scripts there is
a tradition of justifying lines not by expanding and contracting spaces,
but by expanding and contracting the cursive links between letters of a
word. By eye, I would say, this is not done uniformly in traditional
manuscripts, but usually applied before the final letter. However, a
more uniform approach might be more appealing.

The Arabic term for this extra line is Taṭwīl, while I use the
equivalent term Mṭilānā in Syriac. Unicode offers the character at
U+0640 in the Arabic block.

> So is this the XePersian's bug or it has got to be fixed inside the xetex
> engine?

When the majority of a line of text is in one of these scripts, this
should be the default method of justification. As such, I believe this
is XeTeX issue rather than something that should be done with any one
package.

Gareth.

-- 
Gareth Hughes

Department of Eastern Christianity
Oriental Institute
Pusey Lane
Oxford
OX1 2LE

+44 (0)1865 610227