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Re: [css3-fonts] Minor Comments Part II

From: John Daggett <jdaggett@mozilla.com>
Date: Sun, 19 May 2013 23:10:42 -0700 (PDT)
To: www-style@w3.org
Message-ID: <1639865258.16369539.1369030242229.JavaMail.root@mozilla.com>
fantasai wrote:

> >> http://dev.w3.org/csswg/css-fonts/#font-size-prop
> >>     # This property indicates the desired height of glyphs from the font.
> >>
> >> Shouldn't that be "desired size"? Because in vertical typesetting
> >> with proportional or non-square glyphs, it's not necessarily the
> >> height.
> >
> > It's generally the height of glyphs and I don't think changing
> > this to "size" adds an clarity to the spec.
> 
> I was going more for accuracy than clarity here. If it's not always
> the height, then we shouldn't use the term height here.

Thinking about your original comment a little more, the 'font-size'
property specifies the height of glyphs before layout operations, it's
no different for proportional and/or non-square glyphs.  So I think
the existing text is just fine, I don't see the need to bring in a
discussion of the complexities of vertical text rendering here.  It
doesn't add clarity and it doesn't affect what implementations will do.

> >>     # The actual value of this property may differ from the computed
> >>     # value due a numerical value on ‘font-size-adjust’ and the
> >>     # unavailability of certain font sizes.
> >>
> >> I suspect we want to specify here that the availability of font
> >> sizes doesn't affect layout or unit conversions. (Alternately,
> >> specify that they do.)
> >
> > This is the same text that is used in 2.1.  The definition of value units
> > belongs in the Values spec, no?
> 
> It is implicit in the Values spec, yes. But since you're talking about
> the difference between computed values and actual values here, I think
> it's also worth pointing out whether
>    - availability of font sizes affects unit conversions
>    - availability of font sizes affects layout

It seems to me the underlying issue is whether units are calculated
based on computed vs. actual used value and *that* issue should be
addressed in the Values spec since it applies beyond the set of
properties defined in this spec. My gut feeling is that it should be
based purely on computed value, so 1em == computed value of
'font-size' regardless of 'font-size-adjust'.

The computed value of 'font-size-adjust' and issues of available font
sizes (including platforms that only support integer font sizes)
obviously affects layout but I'm not sure what you think the spec
needs to say here about that.

Cheers,

John Daggett
Received on Monday, 20 May 2013 06:11:09 UTC

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