[mpeg-OTspec] Registering new GPOS features?

[Behdad Esfahbod]

Thanks Ken.

I agree 'dist' is not ideal, for at least, it's not applied by non-Indic
shapers currently.

What I was hinting at was that maybe we should register one catch-all
required feature that can be used in the future for any such things.
Separating vertical might be the easiest currently. In some future we will
add direction hints to lookups and then it wouldn't be needed anymore.
Currently there's no such catch-all required feature. For GSUB, people do
things with 'ccmp' or 'loca' which are supposed to be always on in all
shapers.

On Thu, Apr 26, 2018 at 5:25 AM, Ken Lunde lunde at adobe.com [mpeg-OTspec] <
mpeg-OTspec-noreply at yahoogroups.com> wrote:

>
>
> Peter & Behdad,
>
> While I am potentially okay with hanging the functionality that I
> described off of the 'dist' GPOS feature, especially if there is resistance
> to register a new feature, I need to point out that a separate feature is
> definitely needed for vertical. A sufficient number of the target
> characters have corresponding glyphs that can be used in both writing
> modes, sometimes as multiples of the same glyph (GID), which is what
> necessitates a separate vertical feature. Does that mean that the
> description of 'dist' needs to be modified, and a corresponding vertical
> feature, perhaps tagged 'vdis', be registered?
>
> Also, 'kern' and 'vkrn' cannot be used for this purpose, because it is
> completely reasonable for a font to include both genuine kerning values
> (for more sophisticated environments) and the contextual spacing that I
> have described (for simpler environments).
>
> Regards...
>
> -- Ken
>
> > On Apr 25, 2018, at 8:08 PM, Peter Constable <petercon at microsoft.com>
> wrote:
> >
> > Agreed: distinct features are needed when a behaviour needs to be
> independently-controllable by users, or if (generally only in
> script-specific cases) a particular sequence of feature application is
> needed to get required GSUB derivations. Otherwise, a separate feature
> serves no purpose other than a bookkeeping mechanism for the font
> developer, or a way to declare a supported capability to customers.
> >
> > From: mpeg-OTspec at yahoogroups.com <mpeg-OTspec at yahoogroups.com> On
> Behalf Of Behdad Esfahbod behdad at behdad.org [mpeg-OTspec]
> > Sent: Wednesday, April 25, 2018 3:02 PM
> > To: Ken Lunde <lunde at adobe.com>
> > Cc: mpeg-OTspec at yahoogroups.com; opentype-list at indx.co.uk
> > Subject: Re: [mpeg-OTspec] Registering new GPOS features?
> >
> >
> > OpenType is designed such that fonts can improve these kinds of things
> without needing a change to be rolled out to every engine first. We just
> need one required feature and all kinds of GSUB/GPOS things can be hung
> onto it. The tags should be reserved for features that are either need to
> be controlled by shaper, or by user. Everything else should be just one
> required feature.
> >
> > On Wed, Apr 25, 2018 at 1:48 AM, Ken Lunde lunde at adobe.com
> [mpeg-OTspec] <mpeg-OTspec-noreply at yahoogroups.com> wrote:
> >
> > Behdad,
> >
> >
> > While I see some parallels, the Indic nature of 'dist', along with the
> fact that a corresponding vertical feature is necessary, makes me think
> that separate features is better.
> >
> > Also, and this is for others, I just noticed that a fair number of
> OpenType feature tags in the spec are surrounded by smart double quotes,
> while most are surrounded by single straight quotes. I counted that 16
> features have this issue. See the attached screenshot to see the first
> three.
> >
> > Regards...
> >
> > -- Ken
> >
> >
> > On Apr 24, 2018, at 3:39 PM, Behdad Esfahbod <behdad at behdad.org> wrote:
> >
> > 'dist' feature?
> >
> > <image003.png>
> >
> >
> >
> >
> > --
> > behdad
> > http://behdad.org/
> >
>
> 
>



-- 
behdad
http://behdad.org/
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