Re: [css3-writing-modes] real vs. synthetic width glyphs

On 07/01/2013 01:07 AM, John Daggett wrote:
> I would propose that the process of laying out tatechuyoko runs be:
> 1. Convert full-width codepoints to their default equivalents (i.e.
>     full-width digits would switch to their ASCII digit equivalents)
> 2. Based on the length, apply the appropriate OpenType feature
>     (i.e. half/third/quarter width)
> 3. Scale the result to 1em if necessary
> 4. Treat the resulting composition of glyphs as a single glyph that
>     matches the metrics of typical ideographic glyphs for the font used
>     (i.e. does *not* affect the size of the inline box).  The resulting
>     composition of glyphs is defined to have no available substitions
>     (i.e. none of the font-variant/font-feature-settings affect the
>     rendering of the composition).

Alright, I've tried to add your proposed algorithm as resolved in

I'm not sure how 'font-feature-settings' fits into this picture,
but I tried my best to make things well-defined, within the context

My goal was to allow variations (1), (4), and (5) in your examples:
And to make it clear that UAs are expected to use appropriate glyph
variants where possible, which I think the new text does fairly well.

> One additional note, I think the possible set of values for use with
> 'digits' should be limited to 2, 3, 4.  Anything else is nonsensical,
> theoretically possible but illegible in practice.

I've limited it to 1-4. A value of 1 actually does make a difference:
it puts single digits upright. ;) Which might be desired. *shrug*


Received on Wednesday, 10 July 2013 06:45:24 UTC