Re: Making necessary OpenType features on by default

[Khaled Hosny <khaledhosny@eglug.org>]

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On Fri, Feb 20, 2009 at 12:31:49PM -0700, Idris Samawi Hamid ادريس سماوي حامد wrote:
> On Fri, 20 Feb 2009 11:57:22 -0700, Hans Hagen <pragma@wxs.nl> wrote:
>
>> Khaled Hosny wrote:
>>
>>> Currently, when defining a font feature one has to enable all features
>>> by hand which is IMHO not very user friendly as it implies prior
>>> knowledge about OpenType font features and the meaning of each one, not
>>> every Arabic user, for example, knows what does 'init', 'medi, etc.
>>> ligatures mean yet to know that he must enable them to get proper font
>>> rendering.  I think some font features should be on by default, so that
>>> \definefontfeature[script=arabic] should be enough to get an Arabic font
>>> rendered correctly with the default features as its designer intended
>>> (designers assume that certain will be on while other are off by
>>> default, like liga vs. dlig), and if some one wants to disable a certain
>>> default feature he can turn it off, not the reverse.
>
> Hmm, not sure if this is a good idea, see below.
>
>>>  Microsoft's OpenType features list page
>>> (http://www.microsoft.com/typography/otspec/features_ae.htm) gives a "UI
>>> suggestion" for each feature noting if it should be on by default, I
>>> think those are what most OpenType enable by default (at least the ones
>>> I tested).
>
>> i've been thinking of a features=default option (as there is already  
>> features=yes|no)
>
> Maybe we can have a features=ms_arabic
>
> instead of defaulting to MS' recommendation. So in the final high-end 
> user interface we can have keys like
>
> featureset=ms_arabic

I think the 'ms' part is't really needed, we can just call it"arabic",
or are we going to have more Arabic feature sets?

> But I agree with Hans that this is a matter that needs more thought. For  
> example, Traditional Arabic mixes OpenType and older M$ specs in  
> Uniscribe, so just plugging in the default features that M$ suggests is  
> not sufficient for, eg, vowel function in Tr Ar.

That is beyond OpenType support, since Traditional Arabic is essentially
broken at many levels, even when Uniscribe is used (vowel marks break
lam-alef ligatures for example), Ms Arabic fonts are special case since
they were developed long ago before OpenType and aren't the best
examples.

> Also, what about Arabic  
> fonts on the mac, so they follow the same specs as M$?

AFAIK, Microsoft's Uniscribe is the reference OpenType implementation,
and I assume that Apple's OpenType implementation follows its
recommendations (I can't test that).

>
> We've still got lots to do before settling on a very high-end interface 
> so there is time to think about this some more...

Of course, we aren't in hurry.

Regards,
 Khaled

-- 
 Khaled Hosny
 Arabic localizer and member of Arabeyes.org team

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