Re: [csswg-drafts] [css-text-decor] text-decoration-thickness & text-underline-position properties

@r12a:

> I'm not clear exactly how this works, but baselines are different 
not only for CJK fonts but also for indic fonts (at least nominally), 
which have a hanging baseline

Me neither, so this is a topic i18n needs to think about. Once we 
understand requirements for each languages, I think we can come up 
with how this should work, but we don't understand that yet.

I think we know:

Type | Baseline | Underline position
-----|-----|-----
Latin | Use the 
[alphabetic](https://drafts.csswg.org/css-inline/#valdef-dominant-baseline-alphabetic)
 baseline in CSS, or `romn` baseline in OpenType. | Default to 
slightly below the baseline. When custom, specify the offset from the 
baseline.
CJK | Use the central baseline, or `ideo`. | Default to the bottom of 
em box, or left/right of em box in vertical. When custom, specify the 
offset from the edge of em box. Maybe CK is different from J, I don't 
know.
Indic | Use the hanging baseline, or `hang`. | ???
Any other types? | ??? | ???

and you're right that mixed case needs a separate consideration. I'm 
guessing we should align to the primary script, but it's the case for 
J, and how to determine the primary script is another question.

I discussed with @upsuper offline that CLREQ should have description 
about underline, great if we can understand underline requirements for
 other languages as well.

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Received on Friday, 18 November 2016 05:48:12 UTC