Re: face colors on 256 colors terminals

["Eli Zaretskii" <eliz@gnu.org>]

> Cc: Dan Nicolaescu <dann@ics.uci.edu>,  emacs-devel@gnu.org
> From: David Kastrup <dak@gnu.org>
> Date: Wed, 06 Apr 2005 19:36:27 +0200
> 
> >        The R, G, and B represent single hexadecimal digits.  When
> >        fewer than 16 bits each are specified, they represent  the
> >        most-significant bits of the value (unlike the "rgb:" syn-
> >        tax, in which values are scaled).  For  example,  #3a7  is
> >        the same as #3000a0007000.
> >
> > So I think the code in tty-colors.el is correct in this matter.  It
> > is, however, possible that the RGB values in color-name-rgb-alist were
> > incorrectly scaled from 8-bit variants, and need to be amended.
> 
> Actually, it does not make sense to scale in that way.  #3a7 really
> should be the same as #3333aaaa7777, so that #fff is the same as
> #ffffffffffff, pure white.

That could be so, but:

 (1) The #RRGGBB syntax being a legacy thingy, I don't believe anyone
     will want to change it; and

 (2) As long as X does it this way, so must we, because when Emacs
     runs on X, the #RRGGBB spec is parsed by the X server, not by
     Emacs (Emacs just hands the spec to X).  If tty-colors.el doesn't
     do _exactly_ the same, a color specified by the same #RRGGBB will
     look differently in an xterm and on X.