At 10:32 6/20/2002, Peter_Constable@sil.org wrote:
> >> The potentially interesting question of whether an OpenType fount may be
> >> programmed to produce a two colour display has not been discussed.
>
>Did you raise that question? That's something I might have noticed if it
>had been stated in a two-line post. But I didn't notice it, and I'm
>guessing it's because it was in the midst of some 500 lines.
>
>The question interests me because a while ago now I was amusing myself with
>the idea of being able to do this kind of thing in Graphite (another
>smart-font technology akin to OpenType) in order to emulate dual-coloured
>Ethiopic manuscripts -- specifically, I was thinking of a way to handle the
>paragraph marks that are done with four black dots interspersed with five
>red dots.
>
>Can an OpenType (or Graphite) font be programmed to do this? No. Should the
>technology be revised to accommodate this? There's not a clear enough case
>to warrent the increased complexity, I think. (But it would be possible to
>implement, and it's still amusing to imagine doing so.)
Peter, what do you see as the options for achieving something like this?
Some aspects of colour use in Ethiopic manuscripts can clearly be handled
using markup (e.g. the small, raised red glyphs providing chant
instructions, for which I'm wondering if existing ruby notation solutions
might be easily adapted). The paragraph marker is a tricky problem, though.
William will be thrilled to hear that one option would be to use a PUA
codepoint for a zero-width combining character to represent the red dots,
and include a variant glyph for the Ethiopic paragraph mark that contains
only the black dots (or visa versa). If the user input the standard
paragraph mark U+1368, the default glyph would be used, but if the user
then input the PUA codepoint for the combining dots, we would contextually
change the default paragraph mark for the variant with space for the
combining dots. In VOLT notation:
uni1368 -> uni1368.black
| uni1368.red
This puts us in a position where we can use markup to colour the different
elements. Unfortunately, this has to be done using a PUA codepoint, because
markup applies to characters, not glyphs. By making the formation
contextually dependent on the PUA character, we ensure that a correct
paragraph sign is always shown if the PUA codepoint is not used or if a
font is used that does not contain a glyph for the PUA codepoint (in which
case you would get the paragraph sign followed by a .notdef glyph -- not
pretty, but unambiguous).
John Hudson
Tiro Typeworks www.tiro.com
Vancouver, BC tiro@tiro.com
Language must belong to the Other -- to my linguistic community
as a whole -- before it can belong to me, so that the self comes to its
unique articulation in a medium which is always at some level
indifferent to it. - Terry Eagleton
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