How to use terminal color palette with curses

Question

I can\'t get the terminal color palette to work with curses.

import curses

def main(stdscr):
    curses.use_default_colors()
    for i in range(0,7):
        st         


        

Answer 1

curses.use_default_colors() merely sets the default fg or bg colors to -1, from the man page "init_pair(x,COLOR_RED,-1) will initialize pair x as red on default background and init_pair(x,-1,COLOR_BLUE) will initialize pair x as default foreground on blue."

I always assumed that curses supported only the 8 named "curses.COLOR_..." and usually that's enough but I wanted some spice in my apps so a short time searching found me here. Most likely the majority of terms will support 256 color, and you can use @Hristo Eftimov's code above to just print what ever is supported. I decided to make an alternate color chooser which will show examples of x color number as foreground and background. Arrow keys left/right or keys a/d to change which attribute to alter, +/- to incr/decr the color number, q or esc to quit.

    #!/usr/bin/python
    
    from traceback import format_exc
    import sys, os, time, re, curses
    import locale
    locale.setlocale(locale.LC_ALL, '')
    os.environ.setdefault('ESCDELAY', '250')
    os.environ["NCURSES_NO_UTF8_ACS"] = "1"
    
    move_dirs = {curses.KEY_DOWN : (1, 0), curses.KEY_UP : (-1, 0), curses.KEY_RIGHT : (0, 1), curses.KEY_LEFT : (0, -1),
                 ord('s') : (1, 0), ord('w') : (-1, 0), ord('d') : (0, 1), ord('a') : (0, -1)}
    
    colors = {'white': curses.COLOR_WHITE, 'red': curses.COLOR_RED, 'green': curses.COLOR_GREEN,
              'yellow': curses.COLOR_YELLOW, 'blue': curses.COLOR_BLUE, 'magenta': curses.COLOR_MAGENTA,
              'cyan': curses.COLOR_CYAN, 'black': curses.COLOR_BLACK}
    
    class SuspendCurses():
        def __enter__(self):
            curses.endwin()
        def __exit__(self, exc_type, exc_val, tb):
            newscr = curses.initscr()
            newscr.refresh()
            curses.doupdate()
    
    def cp(i):
        return curses.color_pair(i)
    
    def set_pairs(fg, bg):
        curses.init_pair(1, fg, colors['black'])
        curses.init_pair(2, fg, colors['yellow'])
        curses.init_pair(3, fg, colors['white'])
        curses.init_pair(4, fg, colors['red'])
        curses.init_pair(5, colors['black'], bg)
        curses.init_pair(6, colors['yellow'], bg)
        curses.init_pair(7, colors['white'], bg)
        curses.init_pair(8, colors['red'], bg)
    
    def main_loop(stdscr):
        ret = 0
        EXIT = False
        try:
            curses.curs_set(1) #set curses options and variables
            curses.noecho()
            curses.cbreak()
            maxc = curses.COLORS
            maxy, maxx = stdscr.getmaxyx()
            if maxy < 10 or maxx < 65:
                with SuspendCurses():
                    print('Terminal window needs to be at least 10h by 65w')
                    print('Current h:{0}  and w:{1}'.format(maxy, maxx))
                ret = 1
                EXIT = True
            stdscr.refresh()
            h, w = 10, 65
            test_win = curses.newwin(h, w, 0, 0)
            stdscr.nodelay(1)
            test_win.leaveok(0)
            test_win.keypad(1)
            test_win.bkgd(' ', cp(0))
            test_win.box()
            cursor = [2, 0]
            test_win.move(2, 2+cursor[1]*20)
            fgcol, bgcol = 1, 1
            set_pairs(fgcol, bgcol)
            test_win.refresh()
            cursor_bounds = ((0,0),(0,1))
            teststr = '! @ # $ % ^ & *     _ + - = '
            k, newk = 1, 2
            while not EXIT:
                if k > -1:
                    test_win.clear()
                    if k in move_dirs.keys():  #move cursor left or right with wrapping
                        cursor[1] += move_dirs[k][1]
                        if cursor[1] > cursor_bounds[1][1]: cursor[1] = cursor_bounds[1][0]
                        if cursor[1] < cursor_bounds[1][0]: cursor[1] = cursor_bounds[1][1]
                    if k == 45:  #decr currently selected attr
                        if cursor[1] == 0:
                            fgcol -= 1
                            if fgcol < 0: fgcol = maxc-1
                        else:
                            bgcol -= 1
                            if bgcol < 0: bgcol = maxc-1
                        set_pairs(fgcol, bgcol)
                    if k == 43:  #incr currently selected attr
                        if cursor[1] == 0:
                            fgcol += 1
                            if fgcol > maxc-1: fgcol = 0
                        else:
                            bgcol += 1
                            if bgcol > maxc-1: bgcol = 0
                        set_pairs(fgcol, bgcol)
                    if k in (ord('q'), 27):
                        EXIT = True
                    test_win.addstr(1, 10, '{0} colors supported'.format(maxc), cp(0))
                    test_win.addstr(2, 2, 'FG: {0}  '.format(fgcol), cp(0))
                    test_win.addstr(2, 32, 'BG: {0}  '.format(bgcol), cp(0))
                    for i in range(1,5):
                        test_win.addstr(3+i, 2, teststr, cp(i))
                        test_win.addstr(3+i, 32,teststr, cp(i+4))
                    test_win.move(1, 2+cursor[1]*30)
                    test_win.box()
                    test_win.refresh()
                    curses.napms(10)
                newk = stdscr.getch()
                if newk != k:
                    k = newk
        except KeyboardInterrupt:
            pass
        except:
            ret = 1
            with SuspendCurses():
                print(format_exc())
        finally:
            return ret
    
    if __name__ == '__main__':
        try:
            _ret = curses.wrapper(main_loop)
        except Exception as e:
            print(e)
        finally:
            print('Exit status ' + str(_ret))
            sys.exit(_ret)

Screenshot: