Re: [css3-fonts] "font-feature-settings: none" shorthand?

On Thu, Jun 6, 2013 at 11:01 PM, Levantovsky, Vladimir <
Vladimir.Levantovsky@monotype.com> wrote:

>
>
> On Friday, May 31, 2013 2:01 AM Glenn Adams wrote"
>
> > Let's say for script S, the following features are enabled by default:
> >
> > 'ccmp'
> > 'liga'
> > 'loca'
> > 'kern'
> > 'mark'
> > 'mkmk'
> >
> > Now I could specify:
> >
> > font-feature-settings:
> > 'ccmp' off,
> > 'liga' off,
> > 'loca' off,
> > 'kern' off,
> > 'mark' off,
> > 'mkmk' off;
> >
> > that is, if I happen to know that the implementation enables these by
> default
> > and that the font I'm using uses these, or I could specify:
> >
> > font-feature-settings: none;
> >
> > or, if you prefer,
> >
> > font-feature-settings: off;
> >
>
> In my opinion, the important difference here is 'knowing' vs. 'not
> knowing' what is enabled and what can be turned off. Using a targeted
> approach to turn off a particular feature knowing its initial state is
> fine, but I would be hesitant to give a clueless author a
> "font-feature-settings-shotgun" to experiment with.
>

This is already a low level API. Any author making any use of it needs to
understand OT font functionality. Anyone who uses it at all that doesn't
know OT fonts is already asking for trouble. I don't see that as a problem.
If an author wants to turn off the OT GSUB/GPOS engine on a text specific
basis, that should be possible. I will be supporting this value "none" in
the Apache FOP's usage of font-feature-settings.


>
> > Frankly, this is a very straightforward syntactic shorthand, easily
> > implementable (if one supports font-feature-settings at all).
>
> Given the intricacies of the script-dependent text shaping I am not sure
> if layout engines have readily available APIs to control all default
> features. Without them, what may seem like a straightforward syntactic
> shorthand may become an implementation nightmare.
>

If they add support for font-feature-settings, then supporting "none" is
about a 5 minute exercise.