At 09:28 AM 1/31/2003, Mete Kural wrote:
No. Most complex script shaping is now handled by a combination of shaping engine and font lookups. The shaping engine analyses the text strings, performs any character level pre-processing (e.g. re-ordering for Indic scripts), and then implements specific lookups in the font for glyph substitution and positioning. This means that there is no need for the various contextual forms of Arabic letters to be encoded in a font's character-to-glyph mapping data at all.So does this mean that every character rendered on the screen in a Unicode-enabled program such as Internet Explorer or some editor, have a corresponding presentation form Unicode associated to it?
On Windows, the shaping engines for complex scripts are part of Uniscribe (usp10.dll) and make use of OpenType font technology. An Arabic OpenType font will contain layout features for Initial <init>, Medial <medi> and Final <fini> substitutions (and possibly Isolated <isol>, e.g. to handle contextual variation of the letter heh). Uniscribe analyses strings of Arabic text, keeps track of the position of letters and their neighbours, and implements the appropriate layout feature for each letter.
For more information, see http://www.microsoft.com/typography/developers/opentype/default.htm, and the MS Arabic font specification at http://www.microsoft.com/typography/specs/default.htm
John Hudson
Tiro Typeworks www.tiro.com
Vancouver, BC [EMAIL PROTECTED]
A book is a visitor whose visits may be rare,
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like your shadow and becomes a part of you.
- al-Jahiz, The Book of Animals
