Re: Unicode support

[Eli Zaretskii]

On Wed, 25 Jul 2001, Roozbeh Pournader wrote:

> > > Shouldn't Arabic presentation forms addition be delayed for some
> > > (short) time, in case the user types more characters of the same
> > > word?  Emacs will not normally know how to display the character
> > > just typed: as initial, medial, or final form, since it doesn't know
> > > what will be typed next.
> 
> What I believe to be the best experiment for the user, is having something
> like a U+200D ZERO WIDTH JOINER move with the cursor: when she presses a
> new "letter", remove the last ZWJ (if it exists), add the character to the
> buffer, add the ZWJ, and reshape. If she typed a non-letter, remove the
> ZWJ, add the new character, and reshape. Because the letters are much more
> frequent than non-letter, this strategy will minimize the change of the
> shapes on the screen (which is good for many things, from the
> communication software, to the users's eyes).

Changing shape after each typed character will probably have
undesirable effects on many optimizations used by the Emacs redisplay
engine, specifically those for inserting a single character.  That's
why I suggested to go about it as we do with just-in-time font-lock,
i.e. defer them a bit.