[HarfBuzz] Rendering of Arabic shadda-kasrah

[Jonathan Kew]

On 19/08/2020 19:44, Richard Wordingham wrote:
> On Wed, 19 Aug 2020 20:09:51 +0300
> Eli Zaretskii <eliz at gnu.org> wrote:
>
>> Could someone please look at the discussion and the data of the Emacs
>> bug#34035 (https://debbugs.gnu.org/cgi/bugreport.cgi?bug=34035) and
>> tell whether the fonts that produce incorrect display are faulty, and
>> if so, what is the problem with those fonts?
> There is no evidence of a fault.  The TUS claims that
> kesra between shadda and the consonant came in with metal type.
> Basically, there are two different styles, one with kesra below the
> consonant and one with it below the shadda.  I don't have details of
> what is preferred where, or its social stratification.
>
> Wright (available at www.ghazali.org/arabic/WrightArabicGrammarVol1.pdf
> ), in §11 Remark (e) ɡives a slightly different story and some attempt
> at an indication of regional variation.
>

Yes; how the combination renders is up to the font.

Some fonts even provide a user-selectable feature to control it, e.g. 
https://software.sil.org/scheherazade/support/smart-font-features/.

JK