Re: undo and combining characters

From: Andrew Dunbar (
Date: Tue Apr 23 2002 - 12:07:10 EDT

  • Next message: Andrew Dunbar: "Re: representing characters (was Re: A quick clarification please."

     --- Tomas Frydrych <>
    wrote: >
    > > - type two arabic characters that get drawn as a
    > ligature
    > > - draw a series of Vietnamese combining
    > characters as a single glyph
    > > - etc.
    > I think in the case of the Arabic ligature, these
    > have to be treated
    > as two characters, i.e., pressing backspace after
    > the second one
    > leaves you with the first one. This case is not a
    > real issue, because
    > internally the ligature is stored as two separate
    > characters, ligature
    > is just a way of displaying in them in a way that
    > looks better, it is
    > not a combination character, and it is the
    > responsibility of the
    > shaping engine to do the transformation for drawing
    > on screen, the
    > piece table knows nothing about it -- just try it
    > for yourself with
    > Arabic, AW should handle that quite well :).


    > On the other hand if in Czech I type acute + a, and
    > press
    > backspace, I expect both symbols to disappear
    > because they
    > combination is a single character. In this case it
    > is not an issue,
    > since the acute+a gets stored as a single codpoint,


    Both cases are non issues.

    > but in some
    > other languages this would be an issue.

    Yes in Vietnames and Thai for instance but as long as
    we can render combining characters (aka zero width
    characters) which we pretty much can right now, this
    is also not an issue.

    Andrew Dunbar.

    > Tomas


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