From: Peter Kirk (peter.r.kirk@ntlworld.com)
Date: Wed Jul 23 2003 - 05:51:40 EDT
On 22/07/2003 20:49, John Hudson wrote:
> Thinking about this whole Hebrew encoding/normalisation problem from
> the rendering side -- i.e. in terms of smart font glyph substitution
> and mark positioning -- it seems me that *if* a character is to be
> inserted between two vowels that visually follow a single consonant,
> it would be preferable if this were not a control character. If the
> character is something that is actually painted as a glyph, it is
> incredibly easy to resolve the rendering problems in the font's
> composition/decomposition <ccmp> feature by, for example, ignoring
> marks while 'ligating' the consonant + extra character to the
> consonant glyph alone. This would happen before the mark positioning
> takes place, so would ensure that the presence of the extra character
> does not break mark positioning in the way that actual control
> characters seem to (and which cannot be be included in <ccmp> lookups
> because they are not painted).
>
> Of course, if this problem is thought about from the text search,
> sort, etc. perspective, the presence of a non-control character --
> even an invisible one -- introduces problems, since it changes the
> encoding of the word. As noted previously, users are unlikely to know
> that they must insert an invisible character into search strings. My
> question is whether this is something that can be addressed in search
> engines and other places affected, so that this character could be
> filtered out during operations? Or, failing that, if we might here
> have a use for a new zero-width character that will be ignored during
> search and sort operations --- as control characters like ZWNJ and CGJ
> are -- but which will be painted -- as control characters typically
> are not?
>
> John Hudson
>
> Tiro Typeworks www.tiro.com
> Vancouver, BC tiro@tiro.com
>
>
Couldn't the rendering engine simply treat CGJ as a non-control
character with a blank and zero width glyph? Then it could ligate it in
the way you suggest. As far as I can tell there is no other known use
for CGJ and therefore no need for a rendering engine to process it as a
control character. This behaviour of CGJ can presumably be made
independent of its behaviour in searching and sorting.
-- Peter Kirk peter.r.kirk@ntlworld.com http://web.onetel.net.uk/~peterkirk/
This archive was generated by hypermail 2.1.5 : Wed Jul 23 2003 - 06:39:09 EDT