[HarfBuzz] Some general Arabic script questions

[Khaled Hosny]

On Thu, Dec 09, 2010 at 02:43:54PM +0100, Mikael Hedlund wrote:
> Hi!
> 
> I am implementing basic support for Arabic script, and since I don't read,
> write or speak Arabic, I have
> some general questions where I would be grateful for some confirmation if I am
> on the right track.
> 
> The handling and rendering of Arabic script will be pretty basic, and the plan
> is to support only the 28 basic
> characters including their positional forms, plus the ligature lam + alef, and
> also the Arabic-Indic numerals.
> 1) Is that acceptable as a (minumum) basic Arabic support or is there something
> else I must support?

You need to also support vowel marks, it is a must. Depending on your
intended audience, you may also need to support extra characters like پ,
چ, ڤ and گ (all can be seen in Arabic text).

> 1b) Must/should I support the ligature lam + alef? (I have seen indications
> that it is compulsory in some aspect)

Unless you are using a specially designed font that makes LamAlef
legible without a ligature, the answer is yes.

> 1c) Is there any other ligature that must or should be supported? (I have not
> seen any indications of that, but just to make sure...)

No.

> 2) As I understand, it's not common to do a line-brek within a word, as it is
> in most European scripts.
>    But if I still must wrap within a word, is the following approach reasonable
> or should it be done in some other way?

It is not uncommon, it is not allowed at all, not in the last 1300 years
or so.

>    I was suggested to do like this, but the guy who suggested it was not 100%
> sure if this was the definitive way to do it.
>    1) If possible, do a wrap after a letter that is not joining / connecting to
> the subsequent letter
>    2) If all letters in the word are letter are joined, wrap between two
> arbitrary joining letters but keep the positional form of
>        those letters that are broken apart (i.e. don't change the first letter
> to its final form an the subsequent letter its initial form)

You should avoid breaking inside words at any cost, no other solution
IMO will be accepted by native speakers.

Regards,
 Khaled

-- 
 Khaled Hosny
 Arabic localiser and member of Arabeyes.org team
 Free font developer