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

Re: font-size and accents, again

From: Chris Lilley <chris@w3.org>
Date: Sat, 20 Nov 1999 21:49:38 +0100
Message-ID: <38370962.59E23CCF@w3.org>
To: Erik van der Poel <erik@netscape.com>
CC: www-style@w3.org


Erik van der Poel wrote:
> 
> All,
> 
> I'm still concerned about CSS's "font-size". The CSS2 spec 

where, exactly?

> and several
> members of the CSS community seem to indicate that the CSS font-size
> includes not only the descenders and ascenders, but also any accents
> that might be placed on top of glyphs (e.g. capital E with acute
> accent).

The CSS2 spec talks quite plainly about the ascent being the maximum
unaccenmted height of the font.

> However, I have also seen a couple of sources that give a different
> meaning for the "point size" of a font. For example, "The PostScript
> Font Handbook" says that "Point size is measured from the top of the
> ascender to the bottom of the descender." It says that the ascender is
> "the part of a lowercase letter, such as in b or h, that rises above the
> x-height", while the descender is "the part of a character that extends
> below the baseline, as in g or p".

Yes, that seems right.
> 
> Another source is the Windows API documentation. It says that the height
> of a font with a certain point size can be specified as:
> 
>   lfHeight = -MulDiv(PointSize, GetDeviceCaps(hDC, LOGPIXELSY), 72);
> 
> When lfHeight is negative, the font mapper uses the "character height"
> rather than the "cell height", where cell height is defined to be
> character height plus "internal leading", which is where accents occur:
> 
>   http://msdn.microsoft.com/library/psdk/gdi/fontext_1wmq.htm
>   http://msdn.microsoft.com/library/psdk/gdi/fontext_2zqq.htm
> 
> Now, these discrepancies wouldn't bug me so much if we could somehow
> hide all of this from the user, but there is one area where I believe we
> have to reveal something to the user, and that is the font preferences
> dialog, where we allow users to set their default font size.
> 
> The old Netscape UA code base used negative lfHeight values, so people
> accustomed to that UA may have come to expect the point size to mean the
> unaccented height of the font.

So they should.

>  If the new Mozilla code base suddenly
> switches to positive lfHeight values (to comply with CSS2), 

I don't see how it would make it comply with CSS2.

--
Chris
Received on Saturday, 20 November 1999 15:49:43 GMT

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