Re: [css-ruby] ruby-position: inter-character

On Sep 20, 2014, at 5:12 PM, L. David Baron <dbaron@dbaron.org> wrote:

> On Friday 2014-09-19 10:41 -0500, David Hyatt wrote:
>> On Sep 19, 2014, at 6:23 AM, Richard Ishida <ishida@w3.org> wrote:
>>> I think Dave is on the right track. I think the CSS spec doesn't need to specify in detail how to arrange the bopomofo letters and tones relative to themselves - I think however the Chinese layout requirements document which is in preparation probably should.
>>> 
>>> I propose we carry on.
>> 
>> My preference would be for layout code to do it, since then I can just implement it in WebKit, and it would work with any font. Requiring the font to support it seems impractical to me.
>> 
>> In order for layout code to do it, though, I need really good documentation telling me how to implement it. 
> 
> At first glance, this seems odd to me, though I admit I'm far from
> being an expert in this area.
> 
> Why should bopomofo be unique here?  Isn't the norm that correct
> positioning of glyphs (whether they're combining marks within a
> grapheme cluster or separate grapheme clusters) be handled by the
> font and the positioning of its glyphs, rather than being handled at
> as high a level as CSS layout?  Or is there some particular reason
> for an exception here?

I see a similarity with other font features that layout engines have synthesized in the past if the fonts don't have built-in support. For example, synthesized small caps.

I agree that the font should ultimately do it, but I'm not sure it's practical to wait for the fonts (and OS text engines) to catch up here.

Given the lack of support in existing fonts, I'm expressing a willingness to do the positioning in layout myself, since - assuming the rules are well understood - it doesn't strike me as overly difficult to do so. I don't think there's any reason this has to be a spec requirement though (that the layout engine position the tone marks).

Something like the CSS2.1 small-caps phrasing is all I'd really be asking for in the spec, e.g., section 15.5:

"It is acceptable (but not required) ... "

dave
(hyatt@apple.com)

Received on Sunday, 21 September 2014 05:10:12 UTC