Revision 1.0, 07/30/2003
Questions & Comments : Please mail Prabhat Hegde
Testing Considerations For Mozilla Indic Script Support
- Complex Text Support
- Indic Support in Mozilla
- About Indic Scripts
- Indic Script Input
- Inscript Keyboard Layout for Indic Languages
- Phonetic IME (Solaris specific)
- Indic Script Text -Edit Operations
- Test URLs
- Indic Font Issues
- Hindi Test Cases
- Hindi Testing reports
This document outlines key Indic
language features which will be useful to test Indic (Currently Hindi)
featureset in the browser. The features covered are:
- Output (Display & and Printing)
- Hindi script shaping issues
- Edit Operations.
Complex Text Support (CTL)
Indic Support Mozilla (*nix only)
Mozilla's supports the following
features w.r.t Indic scripts:
- Context Sensitive Shaping and Rendering on Unix platforms using non-intelligent (non-OT) fonts encoded in "sun.unicode.india-0" encoding.
- CTLized Edit operations including Cursor positioning, Insertion, Deletion, Backspacing and Selection.
- Printing through XPrint.
- Features 1-3 above are available for Core-X and XFT2 backends.
- Edit operations in the Mozilla Viewer, Composer and Mail are all covered.
- Mail transfer is via UTF-8.
- Currently no ISCII support in view of lack of content (as in
web-sites that i know of), and lack of registry for ISCII in IANA.
For complete details about Indic Support project, visit www.mozilla.org/projects/ctl.
About Indic Scripts
All Indic Scripts are derived from
the ancient Brahmi script. Describing them is out-of-scope here. You may
find more information at one or more of the following:
The Devanagari Alphabet
The Devanagari alphabet is used for a number of Indian languages and
dialects and closely related to a number of scripts used today in South
Asia, Southeast Asia and Tibet. It is used for Sanskrit, Hindi, Marathi
and Nepali. The alphabet can be divided into:
|Vowels and corresponding Matras||
Indic Script Input
INSCRIPT Keyboard Layouts are the de-facto standard for Indic
Compose/Keyboard Overlay based input. They are as under:
Input Methods (On Solaris10
and Mad-Hatter only)
Indic Script Edit OperationsThis section describes the expected behaviour of Edit operations for Indic Scripts. The most important consideration is that edit operations need to preserve cluster boundaries. Where 'cluster' refers to a unit of display which may be composed of multiple characters in the alphabet. Edit Operation behaviour is common across all Indic scripts.
Languages have their own semantics in dealing with text editing. Some
text processing features which need to adapt to the new semantics are:
- Left and Right arrow should traverse the entire display unit .
- Caret /Cursor placement should not be in the middle of a display unit but should snap to the nearest edge.
- <Delete>/Del key deletes the entire cluster.
- <BKSP>/Backspace composes the cluster by character.
- Character breaking is by a cluster or alternatively a display unit.
- Line breaking is by danda ' '.
- Word breaking is by space.
- Mouse clicks need to snap to the nearest cluster boundary.
- Selection/Cut/Copy/Paste should follow the rules mentioned above
Edit Operation Testing
As described above the following
opertions must be tested:
- Left & Right Arrow Keys
- Left & Right Arrow Keys with <Shift>
- Left & Right Arrow Keys with <Ctrl>
- Mouse Operations
||<Shift> Right Arrow
||Mouse Double-Click/Select Word
||<Shift> <CTRL> Left
||<Shift> <CTRL> Right
||Select clusters in a word -
||Straddle Script boundary -
||Backspace - Delete a character
(Start from end of the word)
||Delete (Start from beginning of
||Delete (Start from beginning of the word)|
Repeat 11-16 above but use Copy instead of Cut
||Insertion (Add a Halant at the
location shown by the cursor)
Same tests should be extended to multiline text.
Devanagari Character Shaping
Shaping is the process by which
characters are rendered in the appropriate presentation forms. Some but
not exhaustive set of rules to cover Devanagari Character Shaping is as
combining with Matra
Note the re-ordering of the choti-I matra.
Samples of context sensitive shaping when consonants are joined together.
Half-forms are valid for all consonants except for र, फ and ढ
Half forms of some alphabets such as ट & ठ are rendered one below the other.
(The first cluster is a case of ra)
Indic Font Issues
The following are some known Indic font encodings:
Linux & Solaris