Re: Making necessary OpenType features on by default

[Hans Hagen <pragma@wxs.nl>]

Otared Kavian wrote:
> Hi Hans, Khaled, and Idris,
> 
> If a humble opinion from an ordinary user may be issued, I agree with 
> Khaled that it would be extremely useful to have some basic default 
> settings for Arabic fonts, and even more generally for any particular 
> fonts used for other languages. This would not prevent those specialist 
> typesetters who want particular features to be turned on, to do so 
> through appropriate mechanisms.
> 
> As a basic user I am frustrated when using mkiv, that most declaration 
> of features are completely cryptic, and not being a specialist of OTF or 
> other font specifications, I don't know which features are essential for 
> writing and typesetting an article in Persian or any language using 
> Arabic alphabet.
> While the following is quite easy to understand and to use in XeConTeXt
> %%%%%%%%%

well, it might be easy to understand given that default features are 
enabled but on the other hand,. when you want to disable a feature you 
need to know what is enabled so in practice you have the same problem

i remember a talk at bachotex about apps dealing with open type where 
compatibility problems showed up when the machinery started to support 
more features, or started to make relationships between features and 
scripts

since tex is supposed to behave in a predictable way, any automatism 
should be visible and basically be on user request so the only way to go 
is by predefined (and agreed upon) features sets, possible different 
defaults per script/language

> \everypar={\setbox0=\lastbox \beginR \box0 }

not that user friendly, and it would break much other functionality in 
context -)

> it is not so easy to figure out how to typeset the same thing in mkiv: 
> for instance the non specialist has to try several fonts which are 
> installed on his system before getting a result…

that's why we need an inventory, else it will always be a gamble and 
surprise what one will get ... (also feature creep is a problem ... i 
really dislike all those documents with funny ancient ligatures that 
just show up because they're enables, even if they make no sense any more)

> % defining a font for Arabic, Persian
> \definefontfeature
>  [CrypticFeatures]
>  [analyze=yes,
>  mode=node,
>  language=dflt,
>  script=arab,
>  aalt=yes,
>  init=yes,
>  medi=yes,
>  fina=yes,
>  isol=yes,
>  liga=yes,
>  mset=yes]
> 
> %\font\Faarsi=Scheherazade*CrypticFeatures at 14pt  % this does not work
> % after trying a few other fonts one finds that the following works:
> \font\Faarsi=arabtype*CrypticFeatures at 14pt

that depends on what Scheherazade supports

 >mtxrun --script font --list --info --pattern=scheherazade 

MtxRun | fontname: scheherazade 

MtxRun | fullname: Scheherazade 

MtxRun | filename: scheherazaderegot.ttf 

MtxRun | 

MtxRun | feature: calt, script: arab, language: kur  snd  urd  dflt 

MtxRun | feature: ccmp, script: arab, language: kur  snd  urd  dflt 

MtxRun | feature: curs, script: arab, language: kur  snd  urd  dflt 

MtxRun | feature: fina, script: arab, language: kur  snd  urd  dflt 

MtxRun | feature: init, script: arab, language: kur  snd  urd  dflt 

MtxRun | feature: mark, script: arab, language: kur  snd  urd  dflt 

MtxRun | feature: medi, script: arab, language: kur  snd  urd  dflt 

MtxRun | feature: mkmk, script: arab, language: kur  snd  urd  dflt 

MtxRun | feature: rlig, script: arab, language: kur  snd  urd  dflt 

MtxRun | feature: salt, script: arab, language: kur  snd  urd  dflt 


so, it seems to depend on calt but turning on calt by default is *not* 
what the ms spec recommends for arabtype

you see the problem?

we need a database and even then agree upon the defaults; when we have 
that we can default (per font/script/lang) to a featureset

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                                           Hans Hagen | PRAGMA ADE
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