[MPEG-OTSPEC] 回复: 回复: [EXTERNAL] Re: Shaping behavior standardization: multi-engine or "Super USE"?

[John Hudson]

On 21082020 8:50 pm, Dave Crossland wrote:
> The number of indic fonts created in the next 25 years is... Not in 
> terminal decline :) I don't want to say how many multiples than the 
> last 25 years... But anything we do to make it easier for the next 
> generation of type designers around the world is, I think, impactful 
> work. 

Yes. I just wouldn't assume that using Indic 3 instead of Indic 2 is 
necessarily making things easier for type designers.

USE pushes more responsibility onto font makers than was the case in the 
script specific shaping engines. I think it is right to do so, because 
of the benefits to users in being able to get scripts supported in 
software more quickly (even to getting support implemented before a 
script is formally published in Unicode, as Andrew and I demonstrated 
for Soyombo*), but the flexibility of the USE cluster model comes at the 
cost of requiring font makers to have a deeper understanding of OTL and 
to look after more aspects of shaping at the lookup level. In that 
respect, making OT fonts for USE is more like making Graphite or AAT 
fonts: the shaper is doing less of the work for you, and you need to set 
up features and lookups to drive the shaping; indeed, for the features 
that produce reordering, one could say that the OT paradigm is reversed 
and rather than the shaper applying the feature the feature is applying 
the shaper.

One of the things I didn't discuss during my TYPO Labs presentation on 
USE** is the requirement to implement format control character 
behaviours at the GSUB lookup level, rather than relying on 
script-specific knowledge at the shaping engine level to apply 
particular features based on string analysis. So the font maker not only 
needs a deeper level of OTL knowledge, but also a deeper level of 
Unicode knowledge.

And that's all fine, and a lot of people will be up for it. But it is a 
paradigm change in OT font making, and it involves some things getting 
harder, not easier.

JH


* http://tiro.com/John/Hudson-Soyombo-DECK.pdf

** http://tiro.com/John/Universal_Shaping_Engine_TYPOLabs.pdf
Video : https://www.typotalks.com/videos/john-hudson/


-- 

John Hudson
Tiro Typeworks Ltd    www.tiro.com
Salish Sea, BC        tiro at tiro.com

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