One issue with inkscape when used as DTP for indic script was, a few indic scripts always wanted hyphenation when text is justified. For example Malayalam has lengthy words and often space is wasted in lines if the text is not automatically hyphenated. But this feature was not available in inkscape. There is a wishlist bug for adding this feature to Inkscape.  I tried to develop an extension for Inkscape to achieve this.

It is on top of the python hyphenation code written by Wilbert  Berendsen. The hyphenation rules, also called as patterns is TeX or
Openoffice itself. So  I can support any language which has TeX hyphenation rules. But, since the hyphenation rules are language specific we need a language selection mechanism for the text first. Then only we can select the rules and do the hyphenation. But it is very tricky to implement.  Asking the language of the text every time it is justified is not a good idea. Setting a language for document is another choice, but what if the text contains multiple languages?  But for Indian languages it is very easy, we can automatically detect the scripts using unicode codepoints and load the rules accordingly. So for the time being, my extension support only English and all Indian languages.

Download the extension from http://thottingal.in/projects/inkscape_hyphenation/inkscape-hyphenation.zip . In GNU/Linux machines,  extract the zip file and copy to /usr/share/inkscape/extensions folder. In Windows , extract to [inkscape installation directory]\extensions folder.  After this close and reopen inkscape. You will see a menu named Hyphenate in Effects->Text menu.    In the document, add a text field, enter text in any indian language. Select the text and apply hyphenation by Effects->Text->Hyphenate. Then change the alignment of text to justify. You will see the text get hyphenated and occupying maximum possible space in the text field

I got satisfactory result with Malayalam and Tamil. I did not test other languages. Following images illustrates hyphenated, justified, two column layout of text done in Inkscape

We had a discussion about this in inkscape mailing list . Some developers suggested to have this feature built in, not as extension.  There are few issues to be solved for that. One thing is language selection as I explained. The other issue is regarding the hyphenation character to be used. Unicode standard insists to use soft hyphen – u00AD as hyphenation character. This is an invisible character. For Malayalam, visible hyphens are not required. But some other languages require the hyphen sign where the word is broken at the end of the line. The rules for whether the soft hyphen should be visible or not visible is not clear in Unicode’s specification. Pango never displays a the soft hyphen. There are criticism on this specification of softhyphen

• Jukka Korpela, Soft hyphen (SHY) – a hard problem?  http://www.cs.tut.fi/~jkorpela/shy.html
• Markus Kuhn, Unicode interpretation of SOFT HYPHEN breaks ISO 8859-1   compatibility. Unicode Technical Committee document L2/03-155R, June 2003. http://www.cl.cam.ac.uk/~mgk25/ucs/L2/03155r-kuhn-soft-hyphen.pdf

So I think there is something to be done from Rendering engine or Unicode need to clarify the confusions.  But Openoffice and HTML rendering engines always make soft hyphen at the end of the line, which is not desired for some languages.

Try this extension, let me know the comments. For small scale DTP works, such as pamphlets, notices, brochures  inkscape is enough. But since inkscape is not primarily a DTP software and does not have paging support, for books and large scale DTP works, it may not work well.

]]> http://thottingal.in/blog/2009/10/03/inkscape-hyphenation-extension/feed/ 2 http://thottingal.in/blog/2009/08/15/ooo_hyphenation_extensions/ http://thottingal.in/blog/2009/08/15/ooo_hyphenation_extensions/#comments Sat, 15 Aug 2009 09:35:45 +0000 Santhosh http://thottingal.in/blog/?p=221 Openoffice Indic Natural Language group announces the availability of the following Openoffice hyphenation dictionary extensions.

1. Malayalam Hyphenation Rules version 1.2
2. Kannada Hyphenation Rules version 1.1
3. Bengali Hyphenation Rules verson 1.1
4. Hindi Hyphenation Rules version 1.1
5. Telugu Hyphenation Rules version 1.0
6. Tamil Hyphenation Rules version 1.0
7. Gujarati Hyphenation Rules version 1.0
8. Panjabi Hyphenation Rules version 1.0
9. Oriya Hyphenation Rules version 1.0
10. Marathi Hyphenation Rules version 1.0

Spellchecker extension for Malayalam is also ready.

For a complete list of writing aids for Openoffice in Indic Languages is available here

Hyphenation Rules for Languages other than Marathi is already packages in Fedora 11. This releases contains updates and bug fixes. Fedora 12 will contains these updates. These extensions are yet to be packaged for Debian/Ubuntu.

More details about hyphenation rules are available here

As I explained importance of hyphenation come into picture when we justify the text. The length of the lines are controlled by the parent tags…. Unicode had defined a special character called soft hyphen for hyphenation denoted by ­ . In HTML, the plain hy­phen is rep­re­sent­ed by the “-” char­ac­ter (- or-). The soft hy­phen is rep­re­sent­ed by the char­ac­ter en­ti­ty ref­er­ence ­ (­ or ­)

User agents-browsers can break the line whenever a soft hyphen is found. So if we have a javascript based implemenation, which insert the softhyphen in between the words based on language specific rules, we can achieve hyphenation in webpages too.

Hyphenator is a project which does exactly the same. “Hyphenator.js brings client-side hyphenation of HTML-Documents on to every browser by inserting soft hyphens using hyphenation patterns and Frank M. Liangs hyphenation algorithm commonly known from LaTeX and Openoffice. “

Hyphenator was not tested for any non-latin languages so far. I tried to add support for Indian languages and the result was satisfactory. I used the
same rules I defined for openoffice. Unlike latin languages, the number of hyphenation patterns for Indian languages is very less and the performance is good because of that.

I have added Malayalam, Tamil, Hindi, Oriya, Kannda, Telugu, Bengali, Gujarati and Panjabi support to it. You can see a working example here. (I wanted to embed one example here. But livejournal doesnot allow javascript inside blog body ). The column layout is done by CSS. Try resizing the browser windows and try a print preview too..

Don’t forget to read the source code of that page. It is very simple. If you want hyphenation in your webpage, all you need is to include the javascript as done in the example. We need to provide the lang attributes for nodes so that the required patterns for that language can be loaded. I placed the new language patterns temporarily in download area of SMC. I will ask the author of Hyphenator to include it in upstream itself. Code is available here

Hyphenation is the process inserting hyphens in between the syllables of a word so that when the text is justified, maximum space is utilized.

Hiphenation is an important feature that DTP softwares provide. For Indian languages there is no good DTP softwares available. XeTex is the only choice to work with unicode and professional quality page layout. But xetex and DTP are not exactly same. Inkscape can be used as temporary solution. But only for small scale works. There is a project going on to add Harfbuzz backend to Scribus, the freedomware DTP package.

Hiphenation is also requred in many other places. Actually it is required where ever we ‘justify’ a block of text in openoffice or any wordprocessors. Same is the case of webpages. If we justify a block of text in ml_IN, let is see what is happening now

Note the long gaps between words. This is a screenshot taken from firefox. The default hiphenation just breaking the lines in space characters. And no doubt that it makes the pages ugly. The problem becomes worse if the length of the word is more and column width is less.

So what is the solution?

Ideal solution : Applications should be aware of the language, its hiphenation rules and should to the hiphenation wherever required.

Openoffice can take hiphenation dictionaries just like spell checkers. But for Indian languages, we are yet to prepare hiphenation dictionaries(more on that later.) . CSS3 draft of w3c has a provision for hyphenate. But it is stil in draft stage

Algorithm For Hiphenation

The basic for all hyphenation algorithms is the hyphenation algorithm, designed by Frank Liang in 1983, which is adopted in TeX. Wikipedia artcle of TeX explain this with very simple example

If TeX must find the acceptable hyphenation positions in the word encyclopedia, for example, it will consider all the subwords of the extended word .encyclopedia., where . is a special marker to indicate the beginning or end of the word. The list of subwords include all the subwords of length 1 (., e, n, c, y, etc), of length 2 (.e, en, nc, etc), etc, up to the subword of length 14, which is the word itself, including the markers. TeX will then look into its list of hyphenation patterns, and find subwords for which it has calculated the desirability of hyphenation at each position. In the case of our word, 11 such patterns can be matched, namely 1c4l4, 1cy, 1d4i3a, 4edi, e3dia, 2i1a, ope5d, 2p2ed, 3pedi, pedia4, y1c. For each position in the word, TeX will calculate the maximum value obtained among all matching pattern, yielding en1cy1c4l4o3p4e5d4i3a4. Finally, the acceptable positions are those indicated by an odd number, yielding the acceptable hyphenations en-cy-clo-pe-di-a. This system based on subwords allows the definition of very general patterns (such as 2i1a), with low indicative numbers (either odd or even), which can then be superseded by more specific patterns (such as 1d4i3a) if necessary. These patterns find about 90% of the hyphens in the original dictionary; more importantly, they do not insert any spurious hyphen. In addition, a list of exceptions (words for which the patterns do not predict the correct hyphenation) are included with the Plain TeX format; additional ones can be specified by the user.

For more details about the algorithm used in Openoffice read this paper by Nemeth Laszlo

Hiphenation in Indian languages.

Unlike English or any other languages, hiphenation in Indian languages are not that much complex. In general following are the rules

• [consonant][vowel][consonat] can be hiphenated as [consonant][vowel] – [consonat] if vowel is not a virama or halant
• Dont split a word after ZWJ
• We can split a word after ZWNJ
• plus any language specific rules. For eg: in ml_IN a line should not start with a chillu letter.

Hiphenation Dictionaries for Indian languages.

Based on the above mentioned rules, Let us try to create hiphenation dictionaries for Indian languages. I will explain this with the help of a Hindi word example: अनुपल्ब्ध.
We have to define the following rules in the dictionary for this

अ1 -> 1 is odd number , ie. word can be splitterd after अ

ु1 -> 1 is odd number , ie. word can be splitterd after ु

1ल -> 1 is odd number , ie. word can be splitterd before ल

1प -> 1 is odd number , ie. word can be splitterd before प

1ब -> 1 is odd number , ie. word can be splitterd before ब

्2 -> 2 is even number , ie. word can NOT be splitterd after ्

1ध -> 1 is odd number , ie. word can be splitterd before ध

So the end result is अ+नु+प+ल्ब्ध

Same way we can create the Hyphenation dictionaries for all other languages. I have prepared the Hyphenation dictionaries for 8 Indian Languages. Download it from the git repo of the SMC.

How to Install a xx_IN hyphenation dictionary.

• Copy the hyphenation dictionay hyph_xx_IN to /usr/share/myspell/dicts folder.
• Create a file at /usr/share/myspell/infos/ooo/ folder named openoffice.org-hyphenation-xx with one line content
  HYPH xx IN hyph_xx_IN
• Run this command sudo update-openoffice-dicts

Open the openoffice writer, Open some fille in your language or type some text. Justify the text. Set the language of the selection by using Tools->Language menu Hiphenate it by using Tools->Language->Hiphenation menu.

Hope it works . I tested only Hindi and Malayalam. For other languages , inform me if you see any problems or if it is not working . Here is the hyphenated Malayalam paragraph. Compare it with the image I showed at the beginning of this blogpost

Ok. so after testing these hyphenation dictionaries, if we provide them to upstream and packaged, hyiphenation problems in openoffice is solved.

But…. How to solve this problem in web pages?!. We will discuss it in next blogpost!

PS: Thanks to Nemeth Laszlo , author of Hunspell and Openoffice Hyphenation for helping me to prepare the hyphenation tables.