10.1.1 Getting LATEX out of XML

Assuming you can get your document out of its wordprocessor format into XML by some method, here is a very brief example of how to turn it into LATEX.

You can of course buy and install a fully-fledged commercial XML editor with XSLT support, and run this application within it. However, this is beyond the reach of many users, so to do this unaided you just need to install three pieces of software: Java, Saxon and the DocBook 4.2 DTD (URIs are correct at the time of writing). None of these has a visual interface: they are run from the command-line in the same way as is possible with LATEX.

As an example, let's take the above paragraph, as typed or imported into AbiWord (see Figure 10.1). This is stored as a single paragraph with highlighting on the product names (italics), and the names are also links to their Internet sources, just as they are in this document. This is a convenient way to store two pieces of information in the same place.

AbiWord can export in DocBook format, which is an XML vocabulary for describing technical (computer) documents — it's what I use for this book. AbiWord can also export LATEX, but we're going make our own version, working from the XML (Brownie points for the reader who can guess why I'm not just accepting the LATEX conversion output).

Although AbiWord's default is to output an XML book document type, we'll convert it to a LATEX article document class. Notice that AbiWord has correctly output the expected section and title markup empty, even though it's not used. Here's the XML output (I've changed the linebreaks to keep it within the bounds of the page size of the printed edition):

<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<book> 
<!-- ================================================== --> 
<!-- This DocBook file was created by AbiWord.          --> 
<!-- AbiWord is a free, Open Source word processor.     --> 
<!-- You may obtain more information about AbiWord 
     at www.abisource.com                               --> 
<!-- ================================================== --> 
<chapter> 
  <title></title> 
  <section role="unnumbered">
    <title></title> 
    <para>You can of course buy and install a fully-fledged 
      commercial XML editor with XSLT support, and run this 
      application within it. However, this is beyond the 
      reach of many users, so to do this unaided you just 
      need to install three pieces of software: <ulink
      url="http://java.com/download/"><emphasis>Java</emphasis></ulink>,
      <ulink
      url="http://saxon.sourceforge.net"><emphasis>Saxon</emphasis></ulink>, 
      and the <ulink 
      url="http://www.docbook.org/xml/4.2/index.html">DocBook 
      4.2 DTD</ulink> (URIs are correct at the time of writing). 
      None of these has a visual interface: they are run from 
      the command-line in the same way as is possible with
      L<superscript>A</superscript>T<subscript>E</subscript>X.</para>
  </section> 
</chapter> 
</book>

The XSLT language lets us create templates for each type of element in an XML document. In our example, there are only three which need handling, as we did not create chapter or section titles (DocBook requires them to be present, but they don't have to be used).

• para, for the paragraph[s];

• ulink, for the URIs;

• emphasis, for the italicisation.

I'm going to cheat over the superscripting and subscripting of the letters in the LATEX logo, and use my editor to replace the whole thing with the \LaTeX command. In the other three cases, we already know how LATEX deals with these, so we can write our templates (see Figure 10.2).

If you run this through Saxon, which is an XSLT processor, you can output a LATEX file which you can process (see Figure 10.3) and view (see Figure 10.4).

Writing XSLT is not hard, but requires a little learning. The output method here is text, which is LATEX's file format (XSLT can also output HTML and other formats of XML).

1. The first template matches ‘/’, which is the document root (before the book start-tag). At this stage we output the text which will start the LATEX document, \documentclass{article} and \usepackage{url}. The apply-templates instructions tells the processor to carry on processing, looking for more matches. XML comments get ignored, and any elements which don't match a template simply have their contents passed through until the next match occurs, or until plain text is encountered (and output).¹

2. The book template outputs the \begin{document} and the \end{document} commands, and between them the apply-templates makes it carry on processing.

3. The para template just outputs its content, but follows it with a linebreak (using the hexadecimal character code x000A (see the ASCII chart in Table C.1).

4. The ulink template outputs its content but follows it with a footnote using the \url command to output the value of the url attribute.

5. The emphasis template surrounds its content with \emph{ and }.

This is a relatively trivial example, but it serves to show that it's not hard to output LATEX from XML. In fact there is a set of templates already written to produce LATEX from a DocBook file at http://www.dpawson.co.uk/docbook/tools.html#d4e2905

1. Strictly speaking it isn't output at this stage: XML processors build a ‘tree’ (a hierarchy) of elements in memory, and they only get ‘serialised’ at the end of processing, into a stream of characters written to a file.

10.2.1 Conversion to Word

There are several programs on CTAN to do LATEX-to-Word and similar conversions, but they do not all handle everything LATEX can throw at them, and some only handle a subset of the built-in commands of default LATEX. Two in particular, however, have a good reputation, although I haven't used either of them (I tend to stay as far away from Word as possible):

• latex2rtf by Wilfried Hennings, Fernando Dorner, and Andreas Granzer translates LATEX into RTF — the opposite of the rtf2latex2e mentioned earlier. RTF can be read by most wordprocessors, and this program preserves layout and formatting for most LATEX documents using standard built-in commands.

• Kirill A Chikrii's TEX2Word for Microsoft Windows is a converter plug-in for Word to let it open TEX and LATEX documents. The author's company claims that ‘virtually any existing TEX/LATEX package can be supported by TEX2Word’ because it is customisable.

One easy route into wordprocessing, however, is the reverse of the procedures suggested in the preceding section: convert LATEX to HTML, which many wordprocessors read easily. The following sections cover two packages for this. Once it's in HTML, you could run it through Tidy to make it XHTML, add some embedded styling using Cascading Style Sheets (CSS), and rename the file to end in .doc, which can fool Word into opening it natively.

10.2.2 LATEX2HTML

As its name suggests, this is a system to convert LATEX structured documents to HTML. Its main task is to reproduce the document structure as a set of interconnected HTML files. Despite using Perl, LATEX2HTML relies very heavily on standard Unix facilities like the NetPBM graphics package and the pipe syntax. Microsoft Windows is not well suited to this kind of composite processing, although all the required facilities are available for download in various forms and should in theory allow the package to run — but reports of problems are common.

• The sectional structure is preserved, and navigational links are generated for the standard Next, Previous, and Up directions.

• Links are also used for the cross-references, citations, footnotes, ToC, and lists of figures and tables.

• Conversion is direct for common elements like lists, quotes, paragraph-breaks, type-styles, etc., where there is an obvious HTML equivalent.

• Heavily formatted objects such as math and diagrams are converted to images.

• There is no support for homebrew macros.

There is, however, support for arbitrary hypertext links, symbolic cross-references between ‘evolving remote documents’, conditional text, and the inclusion of raw HTML. These are extensions to LATEX, implemented as new commands and environments.

LATEX2HTML outputs a directory named after the input filename, and all the output files are put in that directory, so the output is self-contained and can be uploaded to a server as it stands.

10.2.3 TEX4ht

TEX4ht operates differently from LATEX2HTML: it uses the TEX program to process the file, and handles conversion in a set of postprocessors for the common LATEX packages. It can also output to XML, including Text Encoding Initiative (TEI) and DocBook, and the OpenOffice and WordXML formats, and it can create TEXinfo format manuals.

By default, documents retain the single-file structure implied by the original, but there is again a set of additional configuration directives to make use of the features of hypertext and navigation, and to split files for ease of use. This is a most powerful system, and probably the most flexible way to do the job.

10.2.4 Extraction from PostScript and PDF

If you have the full version of Adobe Acrobat (or one of several other commercial PDF products), you can open a PDF file created by pdfLATEX, select and copy all the text, and paste it into Word and some other wordprocessors, and retain some common formatting of headings, paragraphs, and lists. Both solutions still require the wordprocessor text to be edited into shape, but they preserve enough of the formatting to make it worthwhile for short documents. Otherwise, use the pdftotext program to extract everything from the PDF file as plain (paragraph-formatted) text.

10.2.5 Last resort: strip the markup

At worst, the detex program on CTAN will strip a LATEX file of all markup and leave just the raw unformatted text, which can then be re-edited. There are also programs to extract the raw text from DVI and PostScript (PS) files.