Re: Proposal to add 2 Romanian characters

From: John Hudson (
Date: Mon Apr 26 2004 - 19:43:44 EDT

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    Raymond Mercier wrote:

    > John Hudson writes:

    >>Forget dead keys. Dead keys are only useful if you can perform a character level mapping
    >>to a precomposed character code. As such, it is a mechanism that is effectively useless
    >>for composing sequences that need to be rendered as either dynamically composed
    >>combinations (e.g. using OpenType GPOS mark attachment) or unencoded ligatures at the
    >>glyph level (e.g. using OpenType GSUB many-to-one substitution). Rather than having an
    >>'acute dead key', it is better to simply have a combining acute key, and enter the sequence as
    >><Icircumflex, acute>

    > This is new to me. Where do I learn more ?

    Here is an introduction to OpenType glyph processing, which covers the basics of glyph
    substitution and positioning:

    Note that, unlike Apple's AAT and SIL's Graphite formats -- in which all layout
    intelligence is contained within the font and a 'dumb' state engine interprets the
    lookups--, OpenType fonts interact with shaping engines that share responsibilities for
    language shaping. The <ccmp> feature is a glyph substitution feature in a font, applied by
    the shaping engine prior to all other features except <locl>*, which allows default glyphs
    from the character string to be composed into precomposed combination glyphs, or
    decomposed into multiple glyphs (the latter is useful if one wants to fine tune
    positioning of marks, e.g. contextually, for precomposed Unicode diacritic characters).

    The most recent version of the MS Uniscribe script processing DLL (Office 2003 release)
    performs the functions I discussed in my previous message. We recently made Latin-script
    fonts and keyboard drivers for the Lakota language using this technology. As mentioned
    previously, it does require users to be fairly uptodate with their systems and applications.

    John Hudson

    * Localised Forms feature. See discussion about 1/3 down this page:

    Tiro Typeworks
    Vancouver, BC
    I often play against man, God says, but it is he who wants
       to lose, the idiot, and it is I who want him to win.
    And I succeed sometimes
    In making him win.
                  - Charles Peguy

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