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Re: [css3-fonts] font-size-adjust auto issue

From: Andrew Cunningham <lang.support@gmail.com>
Date: Tue, 27 Aug 2013 12:11:34 +1000
Message-ID: <CAGJ7U-WUuF2nL-25bkG3=a4DoA1QsMu2wOpdGR3zd+gs+bodFQ@mail.gmail.com>
To: "Levantovsky, Vladimir" <Vladimir.Levantovsky@monotype.com>
Cc: "Tab Atkins Jr." <jackalmage@gmail.com>, John Daggett <jdaggett@mozilla.com>, W3C Style <www-style@w3.org>, "www-style@gtalbot.org" <www-style@gtalbot.org>
Assuming a page with a lot of Khmer content and some English content. If
the default font that is chosen has an x-height of 0.34 what would happen
to the English text assuming an "auto" value?

A.


On 27 August 2013 12:01, Levantovsky, Vladimir <
Vladimir.Levantovsky@monotype.com> wrote:

> On Sunday, August 25, 2013 12:52 PM Tab Atkins wrote:
> >
> > On Sat, Aug 24, 2013 at 9:37 AM, Levantovsky, Vladimir
> > <Vladimir.Levantovsky@monotype.com> wrote:
> > > Does it mean that if I define
> > >
> > > font-family: Verdana, Futura, Times (with Times being also the default
> > > font)
> > > font-size-adjust: auto
> > >
> > > and I do have Verdana installed on my platform the font choice will be
> > > Verdana but its aspect value will be adjusted to match Times? If this
> > > is the case, this would be counter-productive since we would adjust
> > > legible font to make the text less legible.
> >
> > Yes, it does mean that it'll be adjusted to match Times.  Whether this
> > makes the font less legible is up to individual interpretation, I
> > suppose.
>
> Not so. According to the spec "the relative height of lowercase letters
> compared to their uppercase counterparts is a determining factor of
> legibility". Adjusting a font with larger x-height to match the lower
> x-height will harm the legibility.
>
> > > This also supports my claim that the spec is misleading. It says:
> > >
> > > # Behaves just like <number>, except the number used is the aspect #
> > > value calculated by user agents for the first font in the list of #
> > > fonts defined for the initial value of the ‘font-family’ property.
> > >
> > > One may read "calculated by user agents for the first font in the
> > list
> > > of fonts" and assume that it will match the aspect value of Verdana
> > if
> > > it is present, but the reality and the outcome of defining
> > > font-size-adjust: auto is way different. And the results will be
> > > different for different users on different platforms. So, i am going
> > > back to my question: why the <auto> value is needed?
> >
> > Specs are indeed misleading if you regularly read only the first half
> > of normative sentences.  The "defined for the initial value of the
> > 'font-family' property" is a necessary part of that sentence which
> > makes it clear what is meant - the "initial value" of a property is a
> > term of art in CSS that is defined in the propdef tables.
> >
>
> Agree, but there is also a second sentence there that says that
> "Effectively this is the default font used when ‘font-family’ is not
> otherwise specified." Since in my case (and also in Example 3) the
> font-family is specified, it "effectively" renders the second half of the
> normative sentence irrelevant, and the fact that Figure 19 also shows the
> result of the adjustment when every font in the font-family is adjusted to
> match the x-height of the first font Verdana visually reinforces the
> assumption that this is the expected behavior.
>
> > The use-case for <auto> has been explained - it provides a useful
> > number without the author having to take the time to measure things
> > themselves, and there's a good chance that it matches the font
> > currently being used, since most pages just uses the browser default
> > fonts for most text.  The default font for the browser is presumably
> > nicely legible, such that matching its x-height is acceptable.
>
> This "useful number" will vary from one platform to another, which makes
> its usability highly questionable, especially considering the very first
> sentence that says "For any given font size, the apparent size and
> legibility of text varies across fonts".
>
> > Having all of your fonts match *some* reasonable x-height is useful all
> > by itself; you don't need the ability to specify a specific x-height to
> > make this functionality useful.
> >
>
> Fonts are designed with different x-heights and varied proportions for a
> reason. And, as far as x-heights are concerned, what is reasonable for one
> typeface design may be not so for another. My objection to having <auto>
> value is because it encourages authors to use it blindly, not knowing (and
> having no chance to know precisely) what the effect will be on any given
> platform.
>
> Cheers,
> Vlad
>
>


-- 
Andrew Cunningham
Project Manager, Research and Development
(Social and Digital Inclusion)
Public Libraries and Community Engagement
State Library of Victoria
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Received on Tuesday, 27 August 2013 02:12:03 UTC

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