Re: Control picture glyphs

From: James Kass (
Date: Tue Aug 28 2007 - 10:22:09 CDT

  • Next message: Mark Davis: "Re: Control picture glyphs"

    Mark Davis wrote,

    > And the CJK VS characters should never be visible
    > in a font that has CJK characters.

    " a font that has CJK characters." This is an important point.

    The developer would be well advised to include some kind of glyph
    for VS characters, but only if the font being designed supports
    base characters which can combine with VS characters in valid

    In other words, a font not designed to support math characters
    and which does not support VS characters would be expected to
    display two little boxes for a valid string consisting of a math
    base character plus a VS character.

    If the font supports VS characters for any other sequences, but
    does not support math characters, and the font uses control
    picture glyphs for VS characters, then the above string would
    display as a little box plus the control picture for the VS. If
    this font instead maps zero-width no-contour glyphs with VS
    characters, then the display will just be one free standing little

    Please note that the above rendering descriptions represent the
    way things actually work right now, rather than being an opinion
    concerning optimal performance. I do think, though, that things
    are working just fine.

    Because of the various possible factor combinations, the font
    developer should retain control of font character coverage.

    And, I just can't seem to leave this alone...

    > And the CJK VS characters should never be visible
    > in a font that has CJK characters.

    ...except during input/editing, if the font designer so desires
    and designs accordingly. In this case, though, the display of
    an invalid or unsupported (by the font) sequence would result
    in a display of a control picture rather than being transparent
    to the reader. Font designers can be well aware of this, yet
    choose to use control pictures anyway.

    Best regards,

    James Kass

    This archive was generated by hypermail 2.1.5 : Tue Aug 28 2007 - 10:24:30 CDT