Re: Joining Arabic Letters

From: Philippe Verdy <>
Date: Sat, 31 Mar 2012 02:36:17 +0200

Not really. Even if there is only one typeface involved, the joining
behavior of Arabic letters is normative and in scope.

This means that even if there's a font change between two letters (for
example due to a fallback for some letters or diacritics), each letter
should contonue to adopt its normative joining behavior (i.e.
displaying their correct joining form).

Then the renderer will just make a "best effort" to place the
diacritics on them (even if those diacritics comes from another font
than the base letter), but of course the ligatures of letters will not
be generated, and it's possible that two letters that are normally
joining perfectly will not join completely their joining strokes, even
if each letter is shown in their correct form.

If one wanted to disable the normative joining forms of letters, as
ZWNJ can be used between them.

I also think that the renderer should also be able to use base letters
and diacritics found in a font by decomposing advanced characters that
are encoded in the UCS with a single code point, if ever that
character is not mapped in the font, using a best effort to place the
diacritics, instead of trying to fond a fallback font that would map
the composite character.

Le 30 mars 2012 20:08, Julian Bradfield <> a écrit :
> On 2012-03-30, Andreas Prilop <> wrote:
>> I think a better idea is to have joining glyphs always even for
>> different typefaces. At least the Unicode Standard should say
>> what should happen when Arabic characters of different typefaces
>> follow each other.
> How can it? Unicode is about plain text. As soon as you start talking
> about different typefaces, you're out of scope.
Received on Fri Mar 30 2012 - 19:42:31 CDT

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