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Re: Initial response for font-style issue?

From: Cameron McCormack <cam@mcc.id.au>
Date: Fri, 18 Apr 2008 23:22:44 +1000
To: www-svg@w3.org
Message-ID: <20080418132244.GA23306@arc.mcc.id.au>

Hi Kalle.

Kalle Raita:
> I posted the mail below on March 14th requesting clarification about
> handling of font-style property. As it stands, we soon have to make
> some implementation decisions related to this matter. So, it would
> be nice if the WG could produce some indication of the direction the
> decision is likely to go. Private opinions of the members are also
> appreciated.

Happy to give my personal opinion here.

> The specification gives 'all' as the default value of <font-face>
> font-style:
>  "If the attribute is not specified, the effect is as if a value of
> "all" were specified."

Right.  This is consistent with the @font-face rule from CSS 2 and the
CSS 3 Web Fonts draft.

  http://www.w3.org/TR/CSS2/fonts.html#descdef-font-style
  http://www.w3.org/TR/2002/WD-css3-webfonts-20020802/#font-style

> For the font-style property, i.e. what is applicable for <text>,
> <tspan>, and <textarea>, the default value is 'normal'
> 
> Looking at the italic texts in the conformance tests, it seems that at
> least tests:
> text-area-220-t
> text-area-213-t

For these two the font-style="italic" doesn’t seem to be important for
the test.  I agree though that it is confusing that this results in the
upright SVG font still being used.

Maybe it would be better to change the SVG font so that it has
font-style="normal" explicitly on the <font-face>?

> fonts-desc-05-t

What is the issue with this one?

> animate-elem-46-t

This test would benefit from the font-style="italic" actually choosing
italic glyphs, too.

> On the other hand, at least test text-intro-201-t, based on the
> reference image, seems to assume that
> the default value of <font-face> font-style is 'all' as specified.  

Right.

> If we have understood the spec correctly, then:
> 
> a) If the default value 'all' is correct and <font-face> 
> does not specify style, then glyphs specified in that font 
> will be used for all styles of that font as is. Meaning 
> that requesting italic for that font X will give the 
> exactly same glyphs as requesting normal. 

Correct.

> b) If 'normal' is the default, the user agent will look 
> further for italic variant. If none is found, the user 
> agent has the option of synthezising oblique glyphs to 
> use in place of italic.

That would be correct, if ‘normal’ were the default.

> Option a) is what the spec says, but the conformance tests are
> pointing to option b). Are the conformance test faulty?

I think the tests should be changed so that the italic text actually
renders in italics.  Changing the SVGFreeSans.svg font so that it
specifies font-style="normal" seems to be the easiest way to do this.

-- 
Cameron McCormack ≝ http://mcc.id.au/
Received on Friday, 18 April 2008 13:23:31 GMT

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