Re: Generic base characters

From: John Hudson (
Date: Wed Jul 18 2007 - 00:23:32 CDT

  • Next message: James Kass: "RE: Generic base characters"

    Sinnathurai Srivas wrote:

    > Mostly all reputable font will have the dotted circle included within
    > it, as this is a code that is defined like any other code. Not worth
    > dicussing about those sub-standard fonts that does not include the
    > dotted circle within the font.

    > If the above is accepted, there is no two solutions as far as font is
    > concerned. It is practicable to assume all fonts must have dotted circle.

    This is not practicable at all. You seem to assume that any font should contain any and
    all characters 'defined like any other code'. This is no only an erroneous assumption, it
    is an impossibility within current font architecture.

    Fonts support specific collections of languages and/or non-linguistic notation systems
    (e.g. mathematics), sometimes in a single script, sometimes in multiple scripts. Many of
    these languages and scripts also require support from layout engines external to the font,
    and in those cases the fonts and the layout engines need to be designed work together. It
    is a recommendation for compatibility with Microsoft's layout engines that any font
    supporting combining mark characters should also support U+25CC with a glyph that is
    suitable for use as a generic base for combining marks, since this is the mechanism that
    Microsoft's Uniscribe shaping engines employ when displaying a combining mark in the
    absence of what the shaping engine considers a legitimate base.

    > It boiles down to rendering engine's behaviour. I'm surpriced to see
    > Unicode does not ownup to problems caused by Unicode. Rendering engines
    > will follow, if Unicode defines the requirement in a logical manner. I
    > do not think developers are doing a chaotic development. I think Unicode
    > is causing a chaotic situation.

    I think you are wrong. Unicode is defining behaviour for scripts as systems. Some
    rendering engines impose additional language-level rules onto the script system, in a
    manner akin to spell-checking. Personally, I think such rules do not belong at this level,
    so disagree with the practice of inserting the dotted circle in display. This is something
    that should happen only if the user requests it, i.e. in the manner of spellcheckers that
    put red lines under what they think are incorrectly spelled words, or like the visual
    display of normally invisible control characters like ZWJ for editing purposes.

    John Hudson

    Tiro Typeworks
    Gulf Islands, BC
    We say our understanding measures how things are,
    and likewise our perception, since that is how we
    find our way around, but in fact these do not measure.
    They are measured.   -- Aristotle, Metaphysics

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