Re: how to determine whether a char can be displayed or not

[Eli Zaretskii]

On Wed, 11 Oct 2000, Kenichi Handa wrote:

> >>  On ttys, I think we should check terminal coding system.
> 
> > If we do that, we need to make sure that all the other tty-related
> > code handles the appropriate single non-ASCII charset in the same
> > manner.  Right now, I'm not sure that Emacs will not barf on a tty
> > when asked to display a non-ASCII font, because as far as Emacs is
> > concerned, display on a tty does not involve fonts.
> 
> I'm not sure what you mean, especially what kind of code you
> mean by "tty-related code".

Sorry for an unclear wording.

What I meant was the code, like on xfaces.c, which manipulates faces on 
non-windowed displays.  The function you wrote seemed to indicate that 
such displays support ``a font'' which includes all the character sets 
that can be safely encoded by the terminal coding system.  I'm not sure 
the face-related code on xfaces.c and elsewhere is consistent with this.  

For example, Fframe_parameters and realize_tty_face return a single
(faked) font name for tty's, no matter what the terminal coding system is
set to.  Also, the font-related members of struct face are not set in
realize_tty_face (with the exception of the font name).  Etc., etc. 

I'm afraid that if a single font-related function will behave as if fonts 
were really supported on tty's, the inconsistency with other parts of 
Emacs, which currently ignore fonts on tty's, will lead to bugs.