Re: [css-ruby] Tone mark of bopomofo in ruby

> Xidorn Quan <quanxunzhen@gmail.com> 於 2015年1月31日 上午6:30 寫道：
> 
> On Sat, Jan 31, 2015 at 4:43 AM, Richard Ishida <ishida@w3.org <mailto:ishida@w3.org>> wrote:
> On 29/01/2015 23:30, Xidorn Quan wrote:
> On Fri, Jan 30, 2015 at 4:47 AM, Koji Ishii <kojiishi@gmail.com <mailto:kojiishi@gmail.com>
> <mailto:kojiishi@gmail.com <mailto:kojiishi@gmail.com>>> wrote:
> 
> 
> The first two points don't make sense to me. We don't hope characters to
> be marked with the whole annotation. We simply hope fonts have special
> values for positioning tone marks to be besides bopomofo. There are only
> less than 40 bopomofo characters, and 4 tone marks. Hence there are no
> more than 160 combinations (even less, because the 20+ consonants won't
> be combined with tone marks, and light tone is not combined besides
> bopomofo, hence actually only about 50). I'm not familiar with OpenType
> features, hence I don't know if it is feasible to handle this with
> features like GPOS (I suspect it is), but it doesn't seem to be harder
> than positioning requirements of scripts like Arabic. In addition, given
> the small number of combinations, I guess it could at least be handled
> with GSUB.
> 
> Thanks for this comment. I think you may be right. I had been coming at the problem after thinking of the fonts out there that encode the actual bopomofo needed for each character within the font. But I think you're right that that's not what we need here.
> 
> The bopomofo to be associated with a character is spelled out by the ruby markup.  I guess all that's needed is a way to render the tone marks in relation to the bopomofo characters.
> 
> In that case, actually, I suppose it would even be possible, as a stop gap, to speed up the process of adoption by creating small fonts that just do bopomofo and using font-family to apply those to the ruby annotations. Such fonts may be relatively easy to produce and distribute, and especially if they are free to use they could therefore allow people to start using bopomofo ruby sooner rather than later.
> 
> Yes, that's a great idea. And I guess it is also possible to develop a tool which extracts bopomofo characters and tone marks from a font, and generates the required bopomofo font automatically, so that authors can make their pages look more consistent?

I think we can provide a subset only contains Bopomobo and tone marks with GPOS feature as a webfont. Authors add CSS font-family value and it's done. For EPUB, we can embedded the subset into the package. But we should find out what GPOS feature fit the usage, or need a new feature registered?[1]

[1] https://www.microsoft.com/typography/otspec/features_fj.htm

> 
> - Xidorn

Bobby