Re: [css-fonts] proposal needed for synthesizing oblique fonts in vertical text

On 17/05/2013 4:21 PM, "John Daggett" <jdaggett@mozilla.com> wrote:
>
>
> Hi Koji,
>
> > > From the use cases and examples you've described, authors want
> > > some form of obliquing (斜体、shatai). That's *not* italics
> >
> > Yes, I've been discussing about how to synthesize oblique. If you
> > were not, what were you discussing about?
>
> >From the use cases and examples you've given, what you appear to be
> talking about is the use case for Japanese obliquing (斜体、shatai).  Yet
> what you're proposing is a modification to the behavior of
> 'font-style: italic'.  What I and others have been saying is that
> Japanese shatai should not be equated with italics, they are different
> features and the usage patterns are quite distinct, even though they
> overlap because some form of obliquing may be involved.
>
> To put it another way, when an author says "use an italic font" they
> are not saying "oblique this text", even though the end result may be
> the same sometimes.
>

I think this is the crux of the issue.

When an author says to use an italic face they assume that an italic font
or an oblique font depending on the font family.

In the absense of an italic or oblique font, the user agent ghats the
instruction to use an italic  font as a  instruction to synthesise an
oblique font where the glyphs are distorted/transformed to attempt to give
the appearance of an oblique font.

This transformation would visually appear to be a transformation from the
baseline.

And my gut reaction is that it is a transformation that is only relevant to
a limited number of scripts.

There is a long history of word processing and text manipulation that has
misused the term italic and it has been applied to scripts where it doesn't
apply or doesn't belong.

Japanese users have been exposed to this synthetic usage. And I agree that
what Koji is refering to neither italisising or obliquing.

But then the same distinction to most of the Unicode repetitoire

Partly we are discussing a confusion of terminology. And that confusion has
existed for quite a while.

I agree that what is needed is different from what font-style does.

But then i also feel that font synthesis needs to also be decoupled from
font-style and a broader apptoach taken to web tupography.

> > 1. The font-style property defines[1]:
> > >> If no italic or oblique faces is available, an oblique face can by
> > >> synthesized by rendering the normal face with a sloping
> > >> transformation applied
> > 2. I requested to define in which direction the sloping transformation
is, especially for East Asian text in vertical flow.
> > 3. In Feb F2F, you wanted to leave it as UA dependent.
> > 4. You updated ED[2] to the new wording as below:
> > >> If no italic or oblique face is available, oblique faces can be
> > >> synthesized by rendering non-obliqued faces with a right sloping
> > >> transformation applied. When synthesizing these faces, the
> > >> transformation should apply to all glyphs in the same way and
> > >> not vary based on codepoint or due to horizontal or vertical line
> > >> orientation.
> > 5. From this, I understood you agreed to define how to synthesize
oblique.
> > 6. But I didn't understand how it looks in vertical flow from the text,
so asked for clarification.
> > 7. You answered you want #2 of my picture[3], or #1 of your picture[4].
> > 8. I said I want #3 of my picture[3], or #2 of your picture[4].
>
> That's a fair summary.  I think my viewpoint has evolved from simply
> thinking the change you're proposing wasn't really important since
> italics are rarely used in vertical text to the realization that the
> mechanism you're proposing is a very poor match for the select set of
> use cases that exist in practice and that the correct parameterization
> of Japanese obliquing is complex enough that it warrants a separate
> property.
>
> Is your thinking that tweaking the behavior of 'font-style: italic' is
> a way of implementing "good enough" Japanese obliquing?
>
> In my mind, the look and usage of a font face with real italics should
> not differ from one made via synthetic obliquing, regardless of the
> writing mode and text orientation.  Given that Japanese obliquing is
> an effect typically only applied to single lines of text, using CSS
> transforms offers authors better control, the obliquing angle can be
> adjusted to either slanted down to the left (左下がり) or slanted down to
> the right (右下がり).
>
> You've proposed that 'font-style: italic' cause "slanted down to the
> right" obliquing but according to Taro [1], "slanted down to the left"
> is the more common usage and those are the examples that show up in
> documentation explaining InDesign's shatai controls [2].  Likewise, your
> formulation of 'font-style: italic' would not support the Harry
> Potter use case you cited since it also slants down to the left:
>
>
http://lists.w3.org/Archives/Public/www-archive/2013May/att-0032/harrypotter-7-193.png
>
> I think we should resolve on the behavior currently in the spec and try to
> tackle Japanese obliquing at the next level.
>
> Regards,
>
> John Daggett
>
> [1] Taro Yamamoto's comments on synthetic italics in vertical text
> http://lists.w3.org/Archives/Public/www-style/2013May/0331.html
>
> [2] examples of Japanese text obliquing effects
> http://lists.w3.org/Archives/Public/www-style/2013May/0334.html
>