Re: Exceeding COLORS

[Bryan Christ]

Thomas,

So I'm a bit more confused now.  I am using extended_color_content() and as soon as "int color" is > 255 the function returns ERR.  I did a simple test with "xterm-direct" and it still doesn't matter.  The debug code snippet in question is this:

retval = extended_color_content(color, r, g, b);

if(retval == ERR) { endwin(); fprintf(stderr, "gc %d\n\r", color); exit(0); }

As soon as the variable "color" becomes 256 it fails returning ERR.  It's behavior seems identical to what is described for the standard color_content() API for which the man pages says:

The first argument must be a legal color  value,  i.e.,  0  through COLORS-1, inclusive.

The man pages really don't say anything about extended_color_content() other than it uses int instead of short.  So why is it rejecting a color value of 256 even when TERM is set to xterm-direct?

I am encountering this with the distro included version of ncurses on Fedora 31.

On Wed, Jan 29, 2020 at 5:53 PM Thomas Dickey <address@hidden> wrote:

On Wed, Jan 29, 2020 at 03:21:21PM -0600, Bryan Christ wrote:
> When ncurses starts up, I know that it looks at the value of "colors" from
> the terminfo entry and sets COLORS accordingly.  However, I also know that
> the underlying terminal supports way more colors and pairs than is
> advertised by the terminfo entry.  Is there a way to forcibly exceed that
> limit?  The following script runs great on the native terminal, but as soon
> as I run in my emulator, under the confines of ncurses, I hit a 256 color
> wall.
>
> !/bin/bash
> awk 'BEGIN{
>     s="/\\/\\/\\/\\/\\"; s=s s s s s s s s;
>     for (colnum = 0; colnum<77; colnum++) {
>         r = 255-(colnum*255/76);
>         g = (colnum*510/76);
>         b = (colnum*255/76);
>         if (g>255) g = 510-g;
>         printf "\033[48;2;%d;%d;%dm", r,g,b;
>         printf "\033[38;2;%d;%d;%dm", 255-r,255-g,255-b;
>         printf "%s\033[0m", substr(s,colnum+1,1);
>     }
>     printf "\n";
> }'

I suspect the issue to resolve is in your emulator - ncurses 6.1 can
_show_  2^24 colors using the xterm-direct terminal description
(though it requires some work to map to/from the different representations),
but it won't show 2^24 colors using xterm-256color

Using the full range of colors requires the *_extended functions,
as I did in picsmap:

https://github.com/ThomasDickey/ncurses-snapshots/blob/master/test/picsmap.c

e.g., these

extern NCURSES_EXPORT(int) init_extended_color(int, int, int, int);
extern NCURSES_EXPORT(int) init_extended_pair(int, int, int);

and the functions where an "opts" parameter was reserved to be null:

https://invisible-island.net/ncurses/man/curs_attr.3x.html

--
Thomas E. Dickey <address@hidden>
https://invisible-island.net
ftp://ftp.invisible-island.net

--

Bryan
<><