Re: Buffer-local faces

[Miles Bader <miles@gnu.org>]

On Tue, May 04, 2004 at 09:37:52AM -0400, Stefan Monnier wrote:
> > It's a much less obvious operation (what does subtracting red from black
> > yield?  [Ok, maybe cyan :-]) and I can't offhand think of any obvious uses
> > for it....
> 
> As I suggested, we might want to add a notion of color composition, so we
> could have a face that make the foreground darker, or redder, or ...

Yeah, that's one of the areas I've wanted to work on -- I was thinking about
things like `darker'/`lighter'/ `more-intense'/`less-intense' color operators
(the latter two automatically choosing darker or lighter depending on the
context), plus `shaded' versions of the same operators (e.g., doing the
operation with a particular tint).

The reason is so that many faces could be written to be independent of
particular background colors; currently many faces only work well in a single
context (as evidenced by the occasional bickering over face colors :-) --
with such operators, they could even work well in dynamic contexts thanks to
face merging.

I don't know about CMY vs. RGB though -- in my somewhat limited experience,
_all_ color systems suck for this of thing... :-)

> I'm not sure what's a useful generalization, maybe a "filtered inheritance"
> where you can specify which attributes are inherited from a given parent.

Yeah, the question is what's a good way to specify it?  It's always tempting
to just throw in lisp code, but we've seen the messes that gets us into with
the signal handlers &c...

-Miles
-- 
`There are more things in heaven and earth, Horatio,
 Than are dreamt of in your philosophy.'