Re: [docbook-apps] fop problems

["Bob Stayton" <bobs at sagehill dot net>]

----- Original Message ----- 
From: "David N. Welton" <davidw@dedasys.com>
To: "Harald Joerg" <haj@oook.m.uunet.de>
Cc: <docbook-apps@lists.oasis-open.org>
Sent: Thursday, February 19, 2004 1:38 AM
Subject: Re: [docbook-apps] fop problems


> Harald Joerg <haj@oook.m.uunet.de> writes:
> 
> > The whole bunch of errors produced by fop is something you can get
> > accustomed to.  I found most of them don't really hurt.
> 
> The problem is the inexistant output, so one or more of them are
> evidently problematic:-)
> 
> > In my PDF files, I've found all of those you have quoted, and I
> > don't bother since apparently the stylesheets contain enough
> > workarounds to make fop create acceptable results.
> 
> > > [INFO] area contents overflows area in line
> 
> > This, however,  is a hint.... (see below)
> 
> > > The resulting PDF file doesn't seem to include parts of my text, bits
> > > of XML such as:
> 
> > >         <varlistentry>
> > >           <term>
> > >         <cmdsynopsis>
> > >           <arg>BeforeScript</arg>
> > >           <arg><replaceable>script</replaceable></arg>
> > >         </cmdsynopsis>
> > >           </term>
> > >           <listitem>
> > >         <para>
> > > [... snipped ...]
> 
> > > Where the cmdsynopsis is more or less not there or 'messed up'
> > > (see the PDF).
> 
> > A variablelist in docbook takes a 'termlength' attribute, and if you
> > are using fop, it is advisable to supply a "good" value here.  I
> > guess that the [INFO] above tries to tell you that fop couldn't fit
> > your term into its place.  IIRC this is a "known" fop issue.
> 
> Hrm... what would a 'good' value be?  It seems odd to have something
> like this - a presentation detail - be present in DocBook itself.

Unfortunately, it is sometimes necessary with the XSL-FO 1.0 specification.
A DocBook variablelist is implemented in XSL-FO as a list-block.
If you don't specify the indent of the paragraphs in a list-block
(the provisional-distance-between-starts property), then the FO
processor uses the default 24pt.  The DocBook stylesheets estimate
a width value by counting characters in the term element
and converting that to a width.  But the stylesheet can't determine
the actual width of the typeset text; only the FO processor can
do that.  So sometimes the estimate is wrong, and the author
has to intervene to help.  I would hope that the next version of
XSL-FO provides better facilities for automatically setting the
indent based on the content of the term elements.

With FOP, setting the indent width may be critical because of a bug
(reported and discussed but not fixed) that puts FOP 
into an infinite loop if the width is too small for the text.

You can set the width using the termlength attribute on variablelist, or
you can use a dbfo term-width processing instruction to restrict
the help to FO output only.  For more info, see:

http://www.sagehill.net/docbookxsl/ListIndents.html

Bob Stayton
Sagehill Enterprises
DocBook Consulting
bobs@sagehill.net



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