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Re: [css3-fonts] font-language-override: substantive comments

From: John Daggett <jdaggett@mozilla.com>
Date: Wed, 29 May 2013 00:45:21 -0700 (PDT)
To: Andrew Cunningham <lang.support@gmail.com>
Cc: www-style <www-style@w3.org>
Message-ID: <671027292.18259923.1369813521457.JavaMail.root@mozilla.com>

Hi Andrew,

While I think it's an interesting idea to think about language system
fallback, I think there's a *much* simpler solution - use a
downloadable font that supports the script/language that you are
interested in displaying correctly, rather than trying to get the
browser to do something you might or might not want via fallback
acrobatics.  *Especially* in the case of scripts that may not be fully
specified, either from an encoding viewpoint or from a script system
viewpoint.

This is one of the big wins of downloadable fonts, they free us all
from having to worry about the complexities of "font stacks" and such.
In a previous era, font stacks were a necessary evil but not now.
Authors can work with type designers to create fonts that display text
just as they want and browsers can avoid the headache of having to
implement complex behavior that's very hard to get right.

Cheers,

John Daggett

----- Original Message -----
From: "Andrew Cunningham" <lang.support@gmail.com>
To: "John Daggett" <jdaggett@mozilla.com>
Cc: "www-style" <www-style@w3.org>
Sent: Wednesday, May 29, 2013 4:23:04 PM
Subject: Re: [css3-fonts] font-language-override: substantive comments

Hi John, 

I am aware of what is meant by 'font-language-override' and in this
case i meant 'font-language-override' although I am aware that
lang="ksw" would be sufficient for Padauk. The problem is that such a
system is not extensible. Browser developers will implement some
correspondences that occur to them, its not possible to implement more
than a fraction of the potential correspondences. Its not practical.
And browser developers would not have access to the data required.

Another problem with assuming and Karen langauge is associated with
the KAR or KSW langauge system is that Karen langauges can also be
written with other scripts.

For Pwo Karen languages in Thailand you will find Thai script
orthographies, and there is also the Leke script which is being
proposed for inclusion in Unicode.

In essence allowing 'font-language-override' to contain a fall-back
list would be more extensible and easier to implement than using the
value of the lang attribute. The lang attribute approach is practical
and very useful, but not extensible and cannot be comprehensive. 

A slightly more concrete example: 

assuming i have <p lang="pwo"> ... 

or any of the other Karen languages (using Myanmar rather than other scripts) ... 

I still need 

font-language-override: ksw; for Padauk and Padauk Book 

and 

font-language-override: KAR; for Myanmar Text 

alternatively for Padauk and Padauk Book, I could use 

font-feature-settings: "wtri" 1,"lldt" 1; 

to get the same effect, but this will only work on Firefox and only if
graphite support is enabled.

and as of yet I haven't delved into the internals of Myanmar Text to
see if any OT features are available to do something similar. 

Andrew 




On 29 May 2013 17:03, John Daggett < jdaggett@mozilla.com > wrote: 



Hi Andrew, 

Thanks for the example. However, you're mixing up a couple things I think. 


> A practical example would be the fonts Myanmar Text, a system font 
> on Windows 8 which has a language system "KAR" for the Karen 
> languages ant Padauk and Padaik Book which has a language system for 
> S'gaw Karen 'ksw'. 
> 
> If a web developer uses the Padauk font and if browsers fall back to 
> Myanmar Text, there needs to be a way of expressing that. Default 
> rendering, ie Burmese/Mon rendering isn't suitable. 

Language sensitive features are primarily determined by the content 
language of an element, for HTML the 'lang' tag. So language-specific 
behavior can be mapped from a ISO-639 lang tag to the data in the font: 

<p lang="ksw">... 

I think what you seem to be asking for is language system fallback, 
such that if lang="ksw" wasn't available in the font, you'd use 
lang="kar" instead, rather than the default lang="my". Am I getting 
this right? 

The 'font-language-override' is only meant as an *override* for when 
you want to mimic the features of a different language system. 
Specifying the lang attribute is the intended way for authors to 
indicate the language of their content. 

The 'font-language-override' property is also defined in terms of 
*OpenType* language codes, not in terms of ISO 639 lang codes. Padauk 
is a Graphite font that supports language-specific features via ISO 
639 lang codes. It doesn't support OpenType shaping, so 
'font-language-override' doesn't apply in this case. 

Rather than relying on fancy fallback behavior, it would be much better 
to simply use a downloadable font that has the features you need. 

Cheers, 

John Daggett 




-- 

Andrew Cunningham 
Project Manager, Research and Development 
(Social and Digital Inclusion) 
Public Libraries and Community Engagement 
State Library of Victoria 
328 Swanston Street 
Melbourne VIC 3000 
Australia 

Ph: +61-3-8664-7430 
Mobile: 0459 806 589 
Email: acunningham@slv.vic.gov.au 
lang.support@gmail.com 

http://www.openroad.net.au/ 
http://www.mylanguage.gov.au/ 
http://www.slv.vic.gov.au/ 
Received on Wednesday, 29 May 2013 07:45:53 UTC

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