Using TeX hyphenation patterns in OpenOffice.org
Summary: this document describes how to properly use TeX hyphenation patterns in OpenOffice.org and other software using the Hyphen hyphenation library.
Written by Martin Srebotnjak; some portions of text contributed by László Németh and Mojca Miklavec.
- 1 Introduction
- 2 Using TeX patterns
- 3 Conversion of TeX patterns
- 3.1 1. Download up-to-date TeX hyphenation patterns
- 3.2 2. Convert TeX hyphenation patterns file into proper character set
- 3.3 3. Run the substrings.pl conversion script
- 3.4 4. Add hyphenation rules for special characters
- 3.5 5. Create/update the appropriate readme file
- 3.6 6. Create/update an OpenOffice.org dictionary extension
- 4 The future
- 5 Conclusion
The hyphenation files are represented by two files:
- the patterns file (a text file with all the patterns and extra hyphenation rules; hyph_xx_YY.dic) and
- the readme file (a text file with all the credits and licensing information; README_hyph_xx_YY.txt).
The language descriptor xx_YY is an actual ISO-code, you can look it up in the following table: http://wiki.services.openoffice.org/wiki/Languages
From OpenOffice.org 3.0 onwards the hyphenation patterns are packed as an OpenOffice.org extension, usually as a part of a dictionary language pack (with a spell-checking dictionary for the same language and, optionally, a thesaurus). Here is a list of available dictionary language packs: http://extensions.services.openoffice.org/en/dictionaries
Using TeX patterns
Hyphen (and OpenOffice.org) can use TeX hyphenation patters for hyphenation, which is great, because TeX patterns are available for more than 50 different languages.
But because of differences between TeX hyphenation and Hyphen the TeX hyphenation patterns must be first converted. If conversion is not applied, several issues can surface:
- not all TeX patterns will work in OpenOffice.org - which means that TeX patterns will perform substandardly in OpenOffice.org;
- if code-page is not set correctly the TeX patterns can behave erratically in OpenOffice.org;
Conversion of TeX patterns
The following conversion process must be followed step-by-step:
1. Download up-to-date TeX hyphenation patterns
Tex hyphenation repository contains up-to-date TeX hyphenation patterns. They are located here:
Example: for Slovenian language one would download file hyph-sl.pat.txt from the SVN repository.
2. Convert TeX hyphenation patterns file into proper character set
Hyphen for OpenOffice.org (prior to version 3.4) uses ISO-8859-X code-pages while TeX hyphenation patterns are in UTF-8. So conversion of downloaded patterns into proper ISO-8859-X code-page is necessary.
Example: Slovenian language uses ISO-8859-2 code-page, so one would open the UTF-8 file in a code-page savvy text editor, then convert and save it as an ISO-8859-2 coded text.
3. Run the substrings.pl conversion script
Hyphen library (based on libhnj from Raph Levien) uses a time optimized implementation of the original Liang's algorithm of TeX, and substring.pl conversion is a requirement of this implementation. You can download the latest version of substrings.pl conversion script from the Hyphen repository. At the time of writing this was:
The script has the following parameters: the input file name, the output file name, the code-page setting and the LEFTHYPHENMIN and RIGHTHYPHEMIN values that define the minimum left and right length of hyphenated words.
Example: for Slovenian the ISO-8859-2 code page is used, left and right hyphenmin values are 2. So one would use:
./substrings.pl hyph-sl.pat.txt hyph_sl_SI.dic ISO8859-2 2 2
Warning: note how ISO8859-2 is used and not ISO-8859-2! Remember to omit the first hyphen in the ISO codepage name!
4. Add hyphenation rules for special characters
Special characters (apostrophe, hyphen, n-dash, m-dash ...) are word characters in OpenOffice.org, but not boundary characters in the hyphenation of OpenOffice.org which is an incompatibility with the TeX boundary hyphenation patterns. It results in potentially bad hyphenation for words with hyphens and other special characters. Please consider adding the following lines at the end of the converted hyphenation patterns file (hyph_xx_YY.dic):
8-8 8a8-8 8b8-8 8c8-8 ... -a8 -b8 -c8 ...
..." represents all missing lines for other characters of your alphabet.
5. Create/update the appropriate readme file
The readme file contains the credits (author of the patterns, other collaborators...) and licensing information.
Official TeX hyphenation patterns are released under the GNU Lesser General Public License (LGPL) which makes them appropriate for inclusion into OpenOffice.org.
If you use TeX hyphenation patterns from other sources remember to check and mention the license they are available under in the readme file.
The hyphenation patterns to be included in the official OpenOffice.org builds must also include the filled-in http://external.openoffice.org/ form data.
6. Create/update an OpenOffice.org dictionary extension
Package the converted hyphenation patterns in a new (or update the existing) OpenOffice.org extension and upload it to the OpenOffice.org extension repository.
Before uploading try extensively if it works properly with different versions of OpenOffice.org.
If the patterns perform well and the patterns are licensed under LGPL, the patterns could eventually make it into the official releases of OpenOffice.org.
With OpenOffice.org 3.4 support for UTF-8 patters is planned, which would make the Step 2 (from above) obsolete and change the conversion line from Step 3 into:
./substrings.pl hyph-sl.pat.txt hyph_sl_SI.dic UTF-8 2 2
But patterns in UTF-8 will not work with older OpenOffice.org versions (prior to 3.4). However, if you do decide to make an extension version with hyphenation patterns for OpenOffice.org in UTF-8, do not forget to set the required version of OpenOffice.org in the extension description.xml to 3.4 or higher, like this:
<dependencies> <OpenOffice.org-minimal-version value="3.4" d:name="OpenOffice.org 3.4" /> </dependencies>
This will allow older versions of OpenOffice.org to use the older, non-UTF-8 version of your extension.
Since Hyphen engine is used also by other open-source software projects (as are the OpenOffice.org hyphenation patterns files), following these instructions will provide correct patterns for programs like Scribus, KOffice etc.
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