Bug#1010806: apt: Avoid color output on monochrome terminals

[Axel Scheepers <axel.scheepers76@gmail.com>]

Using 'ncolors' for both function and variable isn't really nice but
as is the function will exit when you use it with an unknown terminal
which might not be ok. Maybe using the following would be better;

#include <curses.h>
#include <term.h>

int
ncolors(void)
{
        int err, n = -1;

        if (setupterm(NULL, 1, &err) == OK) {
                n = tigetnum("colors");
                del_curterm(cur_term);
        }

        return n;
}

You should also link ncurses (which brings in a bit of cruft).
Kind regards,
Axel

On Mon, Jan 29, 2024 at 1:53 PM Axel Scheepers
<axel.scheepers76@gmail.com> wrote:
>
> 1010806@bugs.debian.org
>
> On Thu, 26 May 2022 11:03:25 +0200 Axel Scheepers
> <axel.scheepers76@gmail.com> wrote:
> > Or the other way around as I proposed. The entire problem of knowing what
> > and how to use color goes away when curses is used. Would you accept a
> > patch for using that instead?
>
> I've forgot about this but how about the following?
>
> #include <curses.h>
> #include <term.h>
>
> int
> ncolors(void)
> {
>         int ncolors = -1;
>
>         if (setupterm(NULL, 1, NULL) == OK) {
>                 ncolors = tigetnum("colors");
>                 del_curterm(cur_term);
>         }
>
>         return ncolors;
> }
>
> This doesn't initialise the terminal so you can still do the
> progressbar without clearing the screen and/or use hardcoded ansi
> codes for colors if you want. It returns the number of colors for the
> used terminal or -1 if color is not supported. Maybe the progressbar
> should be optional in that case too. I think it would be a nice
> addition and one doesn't have to use apt-get  and/or apt-cache
> instead.
> Also, maybe using italics, bold and reverse video instead of colors
> can be considered? They usually do the right thing with either
> background. Anyway, I hope you can implement the above function to
> make at least monochrome and/or dumb terminals behave.
>
> Kind regards,
> Axel