[XeTeX] New feature planned for xetex

[Jonathan Kew]

On 18/2/16 23:39, Kamal Abdali wrote:
>
> On Thu, Feb 18, 2016 at 9:51 AM, Jonathan Kew <jfkthame at gmail.com
> <mailto:jfkthame at gmail.com>> wrote:
>
>     Here's an example in Urdu script. There are 3 pages, all containing
>     the exact same text.
>
>     Page 1 has \XeTeXinterwordspaceshaping = 0, so this is what existing
>     xetex would produce.
>
>     Page 2 has \XeTeXinterwordspaceshaping = 1, which allows the font to
>     kern across the inter-word spaces; in some cases this makes the
>     space width substantially negative, so that adjacent words actually
>     "overlap" to some degree. This avoids the large visual "gaps" that
>     sometimes occur on page 1, depending on the shapes of the adjacent
>     words.
>
>     Page 3 has \XeTeXinterwordspaceshaping = 2, so we get the exact same
>     line-breaks as page 2, but with some (relatively subtle, mostly)
>     improvements to the actual shaping at word boundaries.
>
>     Hope this helps to illustrate why this feature is important (in
>     certain specialized cases).
>
>
> ​For such effects, I have so far relied on the Word​​​Space option of
> \newfontfamily command in the fontspec package. Two samples
> (urdusample0.pdf and urdusample1_5.pdf) of running xelatex on the same
> Urdu text as yours are attached. ​They have WordSpace set to 0 and 1.5,
> respectively. They are using another Nastaleeq font since I don't know
> anything about Awami.
>
> The new converts to Nastaleeq like the interword spaces eliminated
> completely, and this seems to be the default in Urdu word processors for
> Nastaleeeq. My need is the opposite. As I wouldn't write
> "Thequickbrownfoxjumpsdoverthelazydog"
> in English, I would prefer words to be separate in Urdu also. I don't
> want to start an ideological debate here but mention this just to plead
> to you to allow in your system some way of allowing interword spaces
> liberally.

Note that the new features in xetex do not in any way enforce a 
particular way of writing (for Urdu or anything else). The inter-word 
spacing is primarily under the control of the font designer; 
\XeTeXinterwordspaceshaping merely makes it possible for xetex to more 
accurately follow what the font designer specified.

It is still possible to use TeX features such as \spaceskip (or 
higher-level macros) to adjust things as desired, in cases where you 
want something different from the font's "natural" spacing.

JK