universal_desktop_bar.py

#!/usr/bin/env python3

import subprocess
import re
import sys


OUTPUT_RE = r'(.+) = (.+)'
PROP_CURRENT = '_NET_CURRENT_DESKTOP(CARDINAL)'
PROP_DESKTOPS = '_NET_DESKTOP_NAMES(UTF8_STRING)'
current_desktop = None
desktops = None


def format_desktops(desks, current):
    desks = desks[:]
    desks[current] = '*' + desks[current]
    return ' | '.join(desks)


result = subprocess.Popen(['/usr/bin/xprop', '-spy', '-root'], stdout=subprocess.PIPE)
for line in result.stdout:
    match = re.match(OUTPUT_RE, line.decode())
    if not match:
        continue
    prop = match.group(1)
    val = match.group(2)
    if prop == PROP_CURRENT:
        current_desktop = int(val)
        if not desktops:
            continue
        else:
            print(format_desktops(desktops, current_desktop))
            sys.stdout.flush()
    elif prop == PROP_DESKTOPS:
        desktops = [desk[1:-1] for desk in val.split(', ')]
        print(format_desktops(desktops, current_desktop))
        sys.stdout.flush()