Re: [css3-writing-modes] Re-Summary of Tr in UTR#50 and text-orientation discussions

John,

2013/10/15 John Daggett <jdaggett@mozilla.com>

>
> Makoto Murata wrote:
>
> > I have been wondering whether this debate is about factual
> > matters or subjective value judgement.  Here is my (rough)
> > understanding of John's argument.
> >
> > (1) Since implementation costs are heavy, even optional
> >     fallback should be disallowed.
>
> No, my point is that it's simply *unnecessary* in the context of
> OpenType fonts that supply vertical alternates for nearly all Tr
> codepoints.  This is based on looking at actual fonts rather than
> abstract notions of whether fallback is beneficial or not.  The only
> thing that's subjective is whether one takes the viewpoint that
> this fallback is beneficial even if it only affects a handful of
> codepoints in practice.
>

So, your argument is not strongly based on implementation costs
but rather based on real benefits.  You think that fallback is not
beneficial since it only affects a handful of codepoints in practice.
Apparently, Koji thinks otherwise.  As you said, this is clearly a
subjective issue.  I guess that further discussions will probably go
nowhere, and start to wonder whether the CSS WG is willing to
vote soon.  To me, further delay of writing modes is much
worse than anything else.

Regards,
Makoto


> > (2) Fallback lead to negative side effects.
>
> > (3) Optional fallback confuse authors.
>
> Optional fallback leads to differences in behavior across user agents
> with the same fonts.  For U or R codepoints, when the default
> orientation is not what an author desires, they'll see that it isn't
> correct and use markup to adjust it.  They won't always see this for
> Tr codepoints because the behavior will vary
> across user agents.  Having incorrect behavior for a small set of
> codepoints is not beneficial to users; explicit markup assures that
> it's correct.
>
> In short, existing practice is that the transformation required for Tu
> and Tr codepoints is handled via an OpenType feature.  For situations
> where a font is missing vertical alternates for Tu and Tr codepoints,
> a better made font can be used or, in the case of Tr codepoints,
> explicit markup can be used.
>
> Down the road, as fonts standardize the set of alternates they provide
> based on UTR50, there will be no need for this fallback feature and
> this entire discussion will be moot.
>
> Regards,
>
> John Daggett
>



-- 

Praying for the victims of the Japan Tohoku earthquake

Makoto