RE: DIY OpenType Re-ordering (was: Representative glyphs for combining kannada signs)

From: Peter Constable (
Date: Thu Mar 23 2006 - 00:09:37 CST

  • Next message: Peter Constable: "RE: OT and combining diacritics (was Re: Representative glyphs for combining kannada signs)"

    > From: [] On
    > Behalf Of Vinod Kumar

    > Reordering of glyphs within the font becomes necessary when the font
    > does not have some glyphs. For example, consider Devanagari RDMa. If a
    > glyph gDMa is available then this can be displayed as <gDMA gReph>. If
    > gdMa is absent, but gHalfDa is present then it can be shown as
    > <gHalfDa gMa gReph>. If gHalfDa is absent (the normal case) then the
    > correct display is <gDa gHalant gReph gMA>. In this third case we will
    > need a glyph reordering within the font.

    Not so. The Indic shaping engine in Uniscribe has been updated to accommodate variations in re-ordering based on the nature of the glyph substitutions in the font. The recommendations for Indic OpenType font implementations is in process of being updated to reflect the changes.

    OpenType Layout tables were not designed to support re-ordering, and that should not be attempted in the font. Font implementers should follow the OpenType font recommendations -- these should be treated like a standardized API: interoperability is built on having implementations working from the same assumptions.

    Peter Constable

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