On 07/27/2002 01:17:38 PM "Michael \(michka\) Kaplan" wrote:
>The incompatibility of Linear Tamil in its current form is not with Unicode, >technically; it is with the existing mechanisms of shaping engines used by >Apple, Microsoft, and others. I think you'll find that there is no incompatibility with existing Apple shaping engines. There may be incompatibility with some existing AAT fonts, but not the engine itself. Similarly, both re-ordrant and "linear" Tamil rendering can be implemented in Graphite without requiring any changes in the rendering engine. Of the three smart-font implementations I'm aware of, it's only OpenType -- more precisely, the OT-related rendering engines (Uniscribe, etc.) -- that this applies to. Graphite, AAT and OT can all support implementations that allow rendering of Tamil *both* ways, with the choice controlled by a font feature. This can be done now in AAT and Graphite without requiring any changes in the shaping engine, but it would require changes in OT-related shaping engines to support this. The key distinction is that AAT and Graphite have all script behaviour encapsulated in state machines in the font, whereas in the OT model, handling of script behaviour is divided between the font and the layout engine, specifically with any re-ordering issues handled by the layout engine. There are pros and cons of each approach. Situations like this -- wanting to implement (even if only a prototype for demonstration purposes) "linear" Tamil rendering -- run into the cons of the OT model. (Fortunately for OT implementers, these situations aren't likely to be common. - Peter --------------------------------------------------------------------------- Peter Constable Non-Roman Script Initiative, SIL International 7500 W. Camp Wisdom Rd., Dallas, TX 75236, USA Tel: +1 972 708 7485 E-mail: <[EMAIL PROTECTED]>
