curses is a library for manipulating terminal displays. It was originally developed to support the game rogue on early BSD Unix, but is now widely used to provide an interface for a variety of tools (installers, system conguration, etc.) on Linux and many unix-like platforms. (The original curses has been supplanted by ncurses, which started as a free clone of curses but has become the de-facto extended standard.)
The basic curses unit is the window. Windows which are as large as the entire terminal display are called screens. By default, curses creates two windows/screens: curscr and stdscr. curscr contains the actual current contents of the terminal. stdscr is like an off-screen draw buffer that includes what will be flushed to curscr as soon as we call refresh(). We never really want to touch curscr directly.
Note: when using coordinates, curses orders them as y, x (i.e. high, wide) rather than the more typical x, y.
#!/usr/bin/env python
import curses
import time
def centerStringInWindow(window, string):
height, width = window.getmaxyx()
yorigin = (height / 2) - 1
xorigin = (width / 2) - (len(string) / 2)
window.addstr(yorigin, xorigin, string)
return
def main(stdscr):
stdscr.clear()
hello = 'Hello, world!'
bye = 'Goodbye.'
stdscr.addstr(hello)
stdscr.refresh()
while 1:
c = stdscr.getch()
if c == ord('q'):
stdscr.clear()
centerStringInWindow(stdscr, bye)
stdscr.refresh()
time.sleep(2)
break
elif c == ord('h'):
helpMessage = 'Press "q" to quit.'
centerStringInWindow(stdscr, helpMessage)
stdscr.refresh()
if __name__ == '__main__':
# curses.wrapper takes care of terminal initialization and cleanup for us:
curses.wrapper(main)