On Mon, 4 Aug 1997, Zhenbin Xu wrote:
> Layout control for
> FE characters certainly not so different from Western languages, but the
> word wrapping rules are different. As regard to BiDi languages, things may
> become more complicated, performance may not be satisfactory if every
> controls handles a bunch of things which are not necessary for many users.
> I guess Microsoft will separate the NT5 into two categories, according to
> the direction of characters (LR, RL). Am I right? For those software need
> the capability of handling languages including CJK and BiDi, specially
> designed controls may still well be necessary. If considering support for
> SE Asia languages, such as Thai, Indic scripts, will NT5 become
> insufficient in this matter?
Lori has already answered the more direct questions. Here some
It's an often heard myth that support of things such as CJK, BiDi,
display of south Asian scripts, and so on, slows down performance,
even for Latin, just by being available. This may be true for a
very naive implementation, but not for something well done.
It is very easy to show this with an example. BiDi processing is
really not that easy. So you might guess that you loose a lot of
time on it. However, it is easy to make this faster, in particular
when you don't need it. Just check in the first pass of rendering
a line whether there is any RTL character. If not, just leave the
line as it is, and return. No need for actual Bidi processing.
Also, one should be aware of the fact that to today's computers,
user interaction, for example a fast typist, looks as if ony key
code is comming in each month! So the computer has ample time to
react, if it doesn't decide that it has to render a whole book
when you input a single keystroke.
So really an OS should automatically support a very long list of
languages. The only disadvantage of such an approach is that it
is usually not very well documented, so that it's extremely
difficult to implement your own script if you have to.
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