Re: stacking diacritcs and fullwidth characters

From: James Kass (
Date: Wed Jan 30 2008 - 03:18:10 CST

  • Next message: "Re: stacking diacritcs and fullwidth characters"

    John Knightley wrote,

    > thank-you, GPOS certainly manages to centre the dots correctly-at
    > least in some applications.
    > U+0332 combining low line however needs to be half or full width
    > depending upon the width of the character it is combined with.
    > It would appear from comparng that Code2000 and SIL Doulos use some
    > other mechanism to produce stacking.

    Code2000 uses OpenType GPOS (glyph positioning) tables to stack diacritics
    and to reasonably place diacritics in relation to their base characters. The
    SIL Doulos font most probably uses the same method.

    > For some reason - the stacking feature, by mark to ligature does not
    > seem to work. This however maybe due to other factors.

    Can you post a graphic example of the notation you desire? It
    is said that a picture is worth a thousand words, and this might
    help us understand the desired behaviour.

    The fullwidth presentation forms of Latin characters (and western digits)
    may present an interesting problem. I'd have to check, but I'm pretty
    sure that I've made no allowances for any of them using GPOS and
    combining marks. I'm also not sure if a rendering engine will attempt
    to shape characters from that range, but it would make for an interesting

    (Even the ASCII digits -- I had not considered that anyone would need
    to put combining marks with them and so did not make any effort to
    assign what are called "anchor points" to them.)

    Best regards,

    James Kass

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