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

[John Hudson]

On 21082020 1:52 pm, Peter Constable wrote:
> Thirdly, if there is one shaping engine for all scripts, would there 
> be any need at all for LangSys and Feature tables to still be 
> organized hierarchically under different script tags? (That’s another 
> existing obstacle to glyph actions across script-run boundaries.) IOW, 
> instead of a new _/set/_ of script tags, would just _/one/_ new 
> “script” tag suffice? 

That’s where my mind started going today. But I'm not sure all the 
issues that arise can be resolved in that model.

If itemisation and glyph run segmentation is not performed on the basis 
of script tag, and everything using the new USE tag gets processed as a 
single run, how do we handle characters with locl substitution forms 
specific to individual scripts? And if such characters are Unicode 
script=common, are we pushing the segmentation down a level rather than 
removing it?

J.

-- 

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

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