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Re: [css3-fonts] Synthesizing oblique, to which direction in RTL and vertical flow?

From: John Daggett <jdaggett@mozilla.com>
Date: Mon, 4 Feb 2013 19:36:29 -0800 (PST)
To: www-style@w3.org
Cc: "'WWW International' (www-international@w3.org)" <www-international@w3.org>, "CJK discussion (public-i18n-cjk@w3.org)" <public-i18n-cjk@w3.org>, public-i18n-bidi@w3.org
Message-ID: <1176609523.365007.1360035389905.JavaMail.root@mozilla.com>
Koji Ishii wrote:

> In the font-style property[1], it says:
> 
>   A value of 'italic' selects a font that is labeled 'italic',
>   or, if that is not available, one labeled 'oblique'. If no
>   italic or oblique faces is available, an oblique face can
>   by synthesized by rendering the normal face with a
>   sloping transformation applied.
> 
> But it does not state to which direction the slope should be.
> 
> There is no question for slope direction in LTR scripts, but is
> controversial for RTL and for vertical flow. Could this be
> clarified?
> 
> For RTL, there was a post to www-style in 1999[2], and there are
> some discussions on the web[3]. It looks to me that back-slant is
> the right way to go but I'm no experts here.

I'm not sure I see a reason for wading into these waters.  "Synthetic
oblique" is done the same way by all user agents today, modulo the
wackiness in vertical text in IE10.  Synthetic italics, along with
synthetic bold, are holdovers from the days of word processors with
"Italic" and "Bold" buttons that simply applied synthetic transforms if
real faces didn't exist. The right answer here is really to use a font
designed the way an author desires, be it left or right leaning for
RTL scripts.

I really don't think we should try to resolve anything here for the
CSS3 Fonts spec.

> For vertical flow, there are several possibly right answers as in
> the picture here[4], and my investigation concluded that it varies
> by who you ask to:
> a. Most word processor users consider #6 is the right answer.
> b. Professional printers and font designers think differently by
>    context; #2 or #6 for primarily Latin context such as citations,
>    and #3 for primarily Japanese context. In addition, for primarily
>    Japanese context, authors would like to specify directions and
>    angles.
> c. WebKit renders #8 today, and IE10 renders #6.

Where "most word processor users" means "how Word does it"? ;)

Here again, the right answer is to use an italic face.  For upright
ideographic characters I'm mystified why someone would consider #6
to be correct, the rendering of basic ideographic characters shouldn't
vary whether it's included in horizontal or vertical runs.  The Webkit
rendering (#8) seems like the better choice.

In this case also, I don't think we should try and resolve anything
related to this issue for CSS3 Fonts.

Regards,

John Daggett
Received on Tuesday, 5 February 2013 03:36:58 GMT

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