W3C home > Mailing lists > Public > www-style@w3.org > November 1999

Re: font-size and accents, again

From: Todd Fahrner <fahrner@pobox.com>
Date: Fri, 19 Nov 1999 10:10:07 -0800
Message-Id: <v04220807b45b3a0748ce@[170.1.221.2]>
To: erik@netscape.com (Erik van der Poel)
Cc: www-style@w3.org
At 8:57 AM -0800 11/19/99, Erik van der Poel wrote:

>Does the font itself indicate the appropriate leading for a particular
>em size? For example, do TrueType fonts contain any leading hints?

Not per se (except perhaps "TrueType GX" stuff, which had all kinds 
of elaborate layout-oriented hinting, but which never caught on). 
Leading is usually understood as something added to the em. The em, 
though, may be understood as "minimum appropriate leading". Some 
fonts have obviously overgenerous ems - "built in leading."

>Just to confirm, when you say "when set solid", you mean making the
>distance from baseline to baseline equal to the em, right?

Yes. CSS-2's definition of font-size [1] uses this semi-circular 
language: font size is the size the font says it is.

>  > A little leading is almost always a good idea, and a little more is
>>  almost always even better, especially when you don't have to cut down
>>  trees to make room for it. :^)
>
>Basically, you're saying that people ought to try several different
>values of line-height on several platforms, perhaps both on screen and
>paper, before deciding what value to put in their style sheet. Too
>little leading is bad, and too much leading is bad too. You need to find
>the right value.

Er, sure. But I'm puzzled by the part about "several platforms". 
Seems to me that the issue is "several fonts". Are you saying that 
different platforms report/produce different font sizes when 
processing identical font data? The possibility of font substitution 
should be a bigger threat to good results than XP factors per se.

>The bottom of the following document suggests various values for the
>leading, depending not only on the em, but also on the width of the
>column of text:
>
>   http://css.nu/articles/typograph1-en.html

Yes - good stuff. I would add that fonts with large ex-heights 
relative to em (aspects) tend to require more leading than otherwise, 
since relatively generous ascent/descent is optically akin to 
leading. So a really sophisticated "ideal leading" algorithm would 
take line length and font aspect information as inputs, as well as a 
hint about the intended effect. Difficult texts, with long, complex 
sentences, can handle long lines (relative to em) with little 
leading. Lighter stuff, intended to be read quickly, benefits from 
shorter lines and/or more leading. Compare ponderous textbooks (slow, 
wide and dense) to magazines (medium) to newspapers (quick and 
narrow) to greeting cards and street signs (airy, at-a-glance). Of 
course, this is more art than science, so too much talk of algorithms 
is likely to offend some practitioners as vain.



[1] "The font size refers to the size of the font from baseline to 
baseline, when set solid (in CSS terms, this is when the 'font-size' 
and 'line-height' properties have the same value)."
Received on Friday, 19 November 1999 13:10:14 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Monday, 27 April 2009 13:54:01 GMT