W3C home > Mailing lists > Public > www-xsl-fo@w3.org > December 2001

line height

From: Dave Pawson <daveP@dpawson.freeserve.co.uk>
Date: Tue, 04 Dec 2001 18:33:42 +0000
Message-Id: <5.1.0.14.2.20011204183243.020cab40@127.0.0.1>
To: www-xsl-fo@w3.org
Stole this from the xml newsgroup.
The question at the bottom is intrigueing me.

From: Peter Flynn <peter@silmaril.ie>
Newsgroups: comp.text.xml
Subject: Re: How much space does a line with e.g. 12 pt need in centimeters?

Lars Gregersen wrote:

 > On 3 Dec 2001 05:51:21 -0800, vialulu@excite.com (vialulu) wrote:
 >
 >
 >>Hi All,
 >>
 >>I want to figure out how much total line height a font-size with a
 >>certain pt value uses on a resulting PDF file, but in centimeters. I
 >>use FOP to transform XML into PDF, and I'd like to do some page break
 >>calculations based on how big various lines are, but I don't know the
 >>formula other than than 1pt = 1/72 inch.  Do I do something like this
 >>to figure it out, for say a 12pt font-size:
 >>
 >>    12 * 1/72 (inches) * 2.54 (cm) + 10%
 >>    (10% is just a guess for calculating the space
 >>    above and below the font - is there an actual value
 >>    I can use here?)


Line height including leading is often 1.2 times the point size.


 >
 > No, there is no connection between the fontsize and the height of
 > glyphs. You'll have to look at the bounding boxes for each character.

And you probably need to make sure you measure the highest possible
character ascent and the deepest possibly descent. As a guide, this
string is useful "Íl(/Xjy". In practice, this will return approximately
the current point size, but usually slightly less, for complex and now
largely irrelevant historical reasons going back some 500 years.

Is there a function in XSL to retrieve the BB for a given glyph? It's
trivial in LaTeX to find the height and depth of a character or string
but I haven't seen the equivalent in XSL (but that doesn't mean much,
there are lots of unexplored nooks and crannies :-)

///Peter
Received on Tuesday, 4 December 2001 13:34:11 GMT

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