Preface

I am the primary engineer behind UnRTF, however I have received comments and bug reports from various people. These contributors are identified in the source code, when they desired to be mentioned.

Program License

   UnRTF, a command-line program to convert RTF documents to other formats.
   Copyright (C) 2000,2001 Zachary Thayer Smith

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

   The author is reachable by electronic mail at tuorfa@yahoo.com.

Introduction

Converting to HTML

Character Attributes

Character Sets

Text Blocks

Converting to LaTeX

Character Attributes

Character Sets

Text Blocks

Converting to PostScript

Character Attributes

Character Sets

Text Blocks

Extra Features

Converting to Plain Text

Converting to Text with VT100 control codes

Converting to WPML

Features Not Yet Supported

• numbered lists and point lists
• shapes (objects composed of lines, circles etc)
• index entries and index generation
• tables of contents entries and generation
• automatic conversion of embedded images to PNG

Using UnRTF

Compilation

Theory of Operation

The program operates by dealing with each RTF word in order, and interpreting those which are commands. Some RTF command words have parameters in a subtree. The command \info is an example. The program has separate routines to handle such cases. In fact, most commands have separate functions which handle their execution.

When the program was called rtf2htm (up through version 0.17 or so), the output mechanism was based on the production of HTML exclusively. This has now changed, and the abstraction of an OutputPersonality is used allow other output formats. Each format has its own C file, in which all the basic strings for producing text are stored, as well as character conversion tables. Note, RTF itself allows several character sets to be used, so for each output personality there are that many conversion tables.

One or two things that UnRTF does are fairly tricky, such as the conversion of tabular data. RTF encodes tables in an odd way compared to HTML or LaTeX, so the code is accordingly complicated. Suffice it to say that it works, so don't touch it. Do note, PostScript does not have concept of a table, since it is not a document format but a programming language. I will eventually get tables working under PS anyway, by porting my table rendering code over from my HTML viewer, Beest.

I have implemented at least three optimizations to reduce the amount of memory required by the program and the time used for the conversion.

1. Text words and RTF command-words are stored in a hash table. This has the effect of saving memory since commonly occurring words such as "the" and "\par" are not repeated in memory. When the program finishes doing the conversion, it reports the number of words hashed.
2. RTF command-words and pointers to the functions that interpret them are stored in a static hash so that execution can be speedy. This replaces the long if-else sequence once used and greatly speeds up the program.
3. Input data are buffered, to eliminate the large number of calls to the fgetc function. In a modern OS such as Linux this has only a small impact, but under DOS it can really help.

Notes

1. LaTeX is a system of macros for TeX originated by Leslie Lamport
2. WPML is a tentative document format by Zachary Thayer Smith
3. PostScript is a stack-based programming language for printers.