{"id":177,"date":"2011-01-09T14:40:47","date_gmt":"2011-01-09T14:40:47","guid":{"rendered":"http:\/\/www.readytext.co.uk\/?p=177"},"modified":"2013-11-28T08:58:01","modified_gmt":"2013-11-28T08:58:01","slug":"latex-page-layout-parameters-part-2","status":"publish","type":"post","link":"https:\/\/www.readytext.co.uk\/?p=177","title":{"rendered":"LaTeX page layout parameters (Part 2)"},"content":{"rendered":"

In Part 1<\/a> of this tutorial we looked at the relationship between LaTeX’s page layout parameters and the conventional “DTP” layout model used by designers to parameterise page layout (refer to this diagram<\/a> for a refresher). So, the next step is how do we use the formulae in Part 1<\/a> to do something useful? In this tutorial I will show one way to do this using a Lua script and LuaTeX.<\/p>\n

LuaTeX: a primer<\/strong>
\nIn future tutorials I will explain how to get started with a minimal LuaTeX setup but for present purposes I will have to assume that you have a working LuaTeX installation, perhaps via TeX Live<\/a>, MiKTeX<\/a> or something similar. In essence, LuaTeX is derived from, and extends, pdfTeX<\/a> through the integration of Lua as an embedded scripting language and a whole host of additional functionality<\/a>. It is the integration of the Lua scripting language which, in my opinion, makes LuaTeX so powerful and interesting. To run Lua code you use a LuaTeX command called \\directlua{...}<\/code> where ...<\/code> is your Lua code. Through the \\directlua{...}<\/code> command you can execute your own Lua code and access the “LuaTeX API” which provides a huge range of libraries and functions that give you access to, and control of, many aspects of TeX’s internals through Lua code. This is an extremely simplistic overview, so should you want more information, grab a copy of the LuaTeX Reference Manual<\/a> which is constantly updated as the LuaTeX program evolves. Note that the LuaTeX Reference Manual is a highly technical document which presents the APIs and libraries, it is not <\/em>a user guide and is written by programmers for programmers.<\/p><\/blockquote>\n

Where are we heading?<\/h4>\n

The goal is to create a simple setup so that you can define custom pages and margins through LaTeX code such as this:<\/p>\n

\\documentclass[11pt,twoside]{article}
\n\\input setpage
\n\\setpage{300}{485}{250}{255}{5}{5}{5}{5}
\n\\begin{document}
\n....
\n\\end{document}<\/code><\/p>\n

Where \\input setpage <\/code> inputs a file (called setpage.tex<\/code>) which contains the macro to define a command called \\setpage<\/code>. This takes a number of arguments to define your custom page and margins. Of course, this should be wrapped up into a proper LaTeX package but that is left as an exercise for the reader. <\/p>\n

So, what do we need to do?<\/p>\n

    \n
  1. Create a Lua script that will perform calculations of the formulae presented in Part 1.<\/li>\n
  2. Use \\directlua{...}<\/code> to run the Lua script in (1) via LuaTeX.<\/li>\n
  3. Combine (1) and (2) into a very simple command (\\setpage<\/code>) you can use in your LaTeX document to define custom pages.<\/li>\n<\/ol>\n

    Create a Lua script<\/h4>\n

    The starting point is, of course, that we want to have any size of paper with a document (book, business card etc) centred on the paper area. Because LuaTeX is based on pdfTeX it uses the parameters \\pdfpagewidth<\/code> and \\pdfpageheight<\/code> to set the width and height of the paper (i.e., the PDF page size). See the pdfTeX user manual<\/a> for details. So, using \\pdfpagewidth<\/code> and \\pdfpageheight<\/code> we can set the size of the paper we want to use. Next, we need to know the page size of the document we want to produce. With the PDF paper size and document page size we can calculate the values of \u0394X and \u0394Y to centre the document on our paper. The following SVG graphic (displayed via an iframe) shows the scenario we are aiming for.<\/p>\n