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):
        stdscr.addstr("Hello", curses.color_pair(i))
    stdscr.getch()

curses.wrapper(main)

This python script yields the following screen:

However, I do have more colors in my gnome-terminal palette. How can I access them within curses?

Answer 1

The following I figured out by experiment on my own pc (Ubuntu 14.04, python 3).

• There are 256 colors (defined by the first 8 bits).
• The other bits are used for additional attributes, such as highlighting.
• Passing the number -1 as color falls back to the default background and foreground colors.
• The color pair 0 (mod 256) is fixed on (-1, -1).
• The colors 0 till 15 are the terminal palette colors.

Consider the following testing code. Add this to your .bashrc:

# Set proper $TERM if we are running gnome-terminal
if [ "$COLORTERM" == "gnome-terminal" ]
then
    TERM=xterm-256color
fi

Put this in a python file and run it.

import curses

def main(stdscr):
    curses.start_color()
    curses.use_default_colors()
    for i in range(0, curses.COLORS):
        curses.init_pair(i + 1, i, -1)
    try:
        for i in range(0, 255):
            stdscr.addstr(str(i), curses.color_pair(i))
    except curses.ERR:
        # End of screen reached
        pass
    stdscr.getch()

curses.wrapper(main)

Running it will yield the following output.

As you see, the colors pairs 1-16 are the terminal color palette for foreground colors.