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

From: John Daggett <jdaggett@mozilla.com>
Date: Thu, 16 May 2013 23:19:02 -0700 (PDT)
To: www-style@w3.org
Message-ID: <1607574538.16004126.1368771542937.JavaMail.root@mozilla.com>

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.

> 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
Received on Friday, 17 May 2013 06:19:34 UTC

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