How to Add ANSI Color to User Response

Thu Apr 11 17:41:05 EDT 2024

On 10Apr2024 23:41, Alan Gauld <learn2program at gmail.com> wrote:
>Normally, for any kind of fancy terminal work, I'd say use curses.

My problem with curses is that it takes over the whole terminal - you 
need to manage everything from that point on. Great if you want it (eg 
some full-terminal tool like `top`) but complex overkill for small 
interactive (or not interactive) commands which are basicly printing 
lines of text. Which is what many of my scripts are.
That said, you don't _have_ to use curses to run the whole terminal. You 
can use it to just look up the terminal capabilities and use those 
strings. I haven't tried that for colours, but here's some same code 
from my `cs.upd` module using curses to look up various cursor motion 
type things:
 ... up the top ...
 try:
 import curses
 except ImportError as curses_e:
 warning("cannot import curses: %s", curses_e)
 curses = None
 ... later we cache the available motions ...
 try:
 # pylint: disable=no-member
 curses.setupterm(fd=backend_fd)
 except TypeError:
 pass
 else:
 for ti_name in (
 'vi', # cursor invisible
 'vs', # cursor visible
 'cuu1', # cursor up one line
 'dl1', # delete one line
 'il1', # insert one line
 'el', # clear to end of line
 ):
 # pylint: disable=no-member
 s = curses.tigetstr(ti_name)
 if s is not None:
 s = s.decode('ascii')
 self._ti_strs[ti_name] = s
 ... then a method to access the cache ...
 def ti_str(self, ti_name):
 ''' Fetch the terminfo capability string named `ti_name`.
 Return the string or `None` if not available.
 '''
 return self._ti_strs.get(ti_name, None)
 ... and even later, use the method ...
 # emit cursor_up
 cursor_up = self.ti_str('cuu1')
 movetxts.append(cursor_up * (to_slot - from_slot))
Generally, when I add ANSI colours I do it via a little module of my 
own, `cs.ansi_colour`, which you can get from PyPI using `pip`.
The two most useful items in it for someone else are probably 
`colourise` and `colourise_patterns`. Link:
https://github.com/cameron-simpson/css/blob/26504f1df55e1bbdef00c3ff7f0cb00b2babdc01/lib/python/cs/ansi_colour.py#L96
I particularly use it to automatically colour log messages on a 
terminal, example code:
https://github.com/cameron-simpson/css/blob/26504f1df55e1bbdef00c3ff7f0cb00b2babdc01/lib/python/cs/logutils.py#L824