Re: Colors on TTY (v26)

[Eli Zaretskii <eliz@gnu.org>]

> From: Aleksey Midenkov <midenok@gmail.com>
> Date: Sun, 31 Mar 2019 11:22:59 +0300
> 
> Trial and error shown that emacs holds special knowledge on terminal names:
> f.ex. "xterm-something" works as 256 colors and "xterm2" works as 16
> colors. This is in fact very strange because there are terminals like
> "screen.xterm-256color".
> So it's not good to hold special magic about term names for that. Why it
> doesn't check terminfo db for that (though it checks for 24bit as doc
> states)? Looks like a bug to me.
> 
> To test it:
> 1. infocmp your current term into file;
> 2. rename file and rename term inside it;
> 3. tic renamed file;
> 4. set TERM to renamed term.
> 
> And voila: it's either 256 or 16 colors depending on term name!

Emacs doesn't hard-code terminal names, but it has Lisp libraries
under lisp/term/ which are loaded by the terminal name.  If you have a
terminal that behaves like one of the ones known to Emacs, you need
only copy the relevant Lisp library under lisp/term/ to the name of
your terminal (with the .el extension), and things should work from
there.

> Another bug:
> (list-color-display)
> always shows 16 colors from .emacs file (or from -f option). It detects 256
> colors somehow later and then list-colors-display executed interactively
> shows different result.

The full color list is indeed set during startup, so if you invoke
list-colors-display too early during startup, you will not see that.
This is not a bug, as Emacs can not know the color capabilities of the
terminal until it probes them.