W3C home > Mailing lists > Public > www-style@w3.org > October 2011

Re: List cases for a cap height unit

From: Alan Stearns <stearns@adobe.com>
Date: Wed, 26 Oct 2011 11:01:59 -0700
To: "Tab Atkins Jr." <jackalmage@gmail.com>
CC: www-style list <www-style@w3.org>
Message-ID: <CACD9927.88B4%stearns@adobe.com>
On 10/26/11 10:36 AM, "Tab Atkins Jr." <jackalmage@gmail.com> wrote:

> On Wed, Oct 26, 2011 at 10:13 AM, Alan Stearns <stearns@adobe.com> wrote:
>> It all depends on the font. In some fonts ascent will be significantly
>> taller than cap height, so a lowercase 'f' will loom above a capital "A."
>> What "size of the text" means is a little fuzzy - is it cap height, ascent,
>> the max of those, or an optic average?
> 
> For use case 1, "size of the text" means "a normal height for a
> capital letter, so it blends in typographically".  For use-cases 2 and
> 3, it means "the largest height such that, when the image is placed on
> the baseline, it doesn't change the line's height".
> 
> I *think* that cap height works for both of these definitions.  Am I wrong?

I think cap height works fine for all of the use cases (not necessarily the
definitions, see next para). My point is that using the term "cap height" in
the use case makes the language more precise, and less open to
misinterpretation. I don't want someone to read "as tall as possible" and be
disappointed that they get something slightly less tall than it could have
been.

Your "largest height such that..." definition above does not match cap
height (since ascent can be larger). The use cases work perfectly fine with
cap height, and cap height is guaranteed not to increase the line's height.
It's just not always going to be the largest height that does not increase
the line's height.

>> The discussion so far seems to be around wanting to size things based on cap
>> height, which is perfectly fine. Another possible use case could be wanting
>> to size things based on ascent, which would require a different unit than
>> "cap height." I just want to be precise about what the current proposal will
>> be providing.
> 
> What, precisely, is a use-case for wanting to base something off of
> the ascent?  Describe something an author would want to do, without
> using the word "ascent".  ^_^

Are you trying to define use cases without using the term "cap height?" I
think that would be a mistake.

Thanks,

Alan
Received on Wednesday, 26 October 2011 18:02:28 GMT

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