Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!ukc!strath-cs!cs.glasgow.ac.uk!memex!peter
From: peter@memex.co.uk (Peter Ilieve)
Newsgroups: comp.text
Subject: Re: TeX \vbox trouble
Keywords: TeX \vbox \vfil
Message-ID: <342@memex.co.uk>
Date: 12 Dec 89 09:44:44 GMT
References: <272@oksce1.okstate.edu>
Reply-To: peter@memex.co.uk (Peter Ilieve)
Organization: Memex Ltd., East Kilbride, Scotland
Lines: 44

I tried mail but it bounced, so I will burden everyone with this.

In article <272@oksce1.okstate.edu>
walters@oksce1.okstate.edu (Harold G. Walters) writes:
>
>I'm trying to make an exactly 1 inch \vbox with text set in
>paragraph mode along the bottom of the \vbox.
>
>with the macro
>
>\long\def\oneline#1{\vbox to 1.0in{     
>\vfil{#1}
>}} 
>
>BUT if the bottom line has descenders like
>
>The actual size of the box is greater than 1 inch by an amount
>of the depth of the descenders.  I guess the \vbox is calculating
>the height based on the baseline of the text inside.
>
>IS this what is happening?

Yes, the 1.0in does not include the depth of the text.

>WHY does is happen this way, it seems like a \vbox should contain
>	all of its contents in their entirety?

The box still does contain its contents. The problem is that a \vbox has both a
height and a depth. The "\vbox to 1.0in" construct is DEFINED as only affecting
the height, that's just how TeX is.

>COULD someone tell me how to fix it?

The rules for setting the depth of a \vbox are explained in a "double
dangerous bend" section in Chapter 12 of the TeXbook (page 80 in mine).
One simple thing that will fix it is to put a \vskip 0pt after the {#1}
in your macro definition. A \vbox that has at least one internal box
(the text in your case) gets set with zero depth if the final box is
followed by kerning or glue.

I have tried this here and it works, changing the box in your example from
\vbox(72.26999+1.94444)x469.75499 to \vbox(72.26999+0.0)x469.75499.

	Peter Ilieve		peter@memex.co.uk