Re: Pixel-based display functions

[Eli Zaretskii]

> From: Lars Ingebrigtsen <address@hidden>
> Cc: address@hidden
> Date: Fri, 30 Jan 2015 22:28:40 +1100
> 
> Eli Zaretskii <address@hidden> writes:
> 
> >> The face doesn't say what font is going to be used.  If I put 日本語
> >> here, the entire preceding line has the same face, but two different
> >> fonts.
> >
> > Then check the 'charset' text property as well.
> 
> (get-text-property (point) 'charset)
> => nil
> 
> on that entire line.

Not here, it isn't:

  (get-text-property (point) 'charset) => japanese-jisx0208

on the Kanji characters, and

  (get-text-property (point) 'charset) => nil

on ASCII.

Maybe it depends on how your MUA decodes non-ASCII text.  (I use
Rmail, as you know.)

But I know that the 'face' text property is not enough.  I just
suggest that you use it for now to see if you get enough of speedup in
your code.  We can later find a way of detecting character sets, and
providing new primitives for that, if needed.  (In the display engine,
there's a thing called the "face ID" that is computed as part of
displaying text, which takes the characters into consideration, which
is why I suggested 'face' in the first place.  I will try to see how
to do the same in Lisp.)