I recently upgraded my Mac operating system, and decided to try out a new feature: automatically hiding the menu bar. This gives me back another sliver of vertical space. But it has a drawback: I no longer have the time, battery life, and speaker volume indicators available at a glance.

I went looking for a thing that I figured must exist: a Mac app that would display that information in a dock icon. I already have a dock clock. I found a dock battery indicator, though it tried so hard to be cute and pictorial, I couldn’t tell what it was telling me.

Asking around, I got a recommendation for GeekTool. It lets you draw a panel on your desktop, and then draw in the panel with the output of a script. Now the ball was back in my court: I could build my own thing.

I’d long ago moved the dock to the left side of the screen (again, to use all the vertical space for my own stuff.) This left a small rectangle of desktop visible at the upper left and lower left, even with maximized windows. I drew a panel in the upper left of the desktop, and set it to run this script every five seconds:

#!/usr/bin/env python3.6

import datetime
import re
import subprocess

def block_eighths(eighths):
    """Return the Unicode string for a block of so many eighths."""
    assert 0 <= eighths <= 8
    if eighths == 0:
        return "\u2003"
    else:
        return chr(0x2590 - eighths)

def gauge(percent):
    """Return a two-char string drawing a 16-part gauge."""
    slices = round(percent / (100 / 16))
    b1 = block_eighths(min(slices, 8))
    b2 = block_eighths(max(slices - 8, 0))
    return b1 + b2

now = datetime.datetime.now()
print(f"{now:%-I:%M\n%-m/%-d}")

batt = subprocess.check_output(["pmset", "-g", "batt"]).decode('utf8').splitlines()
m = re.search(r"\d+%", batt[1])
if m:
    level = m.group(0)
    batt_percent = int(level[:-1])
else:
    level = "??%"
if "discharging" in batt[1]:
    arrow = "\u25bc"        # BLACK DOWN-POINTING TRIANGLE
elif "charging" in batt[1]:
    arrow = "\u25b3"        # WHITE UP-POINTING TRIANGLE
else:
    arrow = ""

print(level + arrow)
print(gauge(batt_percent) + "\u2578")   # BOX DRAWINGS HEAVY LEFT

vol = subprocess.check_output(["osascript", "-e", "get volume settings"]).decode('utf8')
m = re.search(r"^output volume:(\d+), .* muted:(\w+)", vol)
if m:
    level, muted = m.groups()
    if muted == 'true':
        level = "\u20e5"        # COMBINING REVERSE SOLIDUS OVERLAY
    print(f"\u24cb{level}")     # CIRCLED LATIN CAPITAL LETTER V

# For debugging: output the raw data, but pushed out of view.
print(f"{'':30}{batt}")
print(f"{'':30}{vol}")

This displays the time, date, battery level (both numerically and as a crudely drawn battery gauge), whether the battery is charging or discharging, and the volume level:

BTW, if you are looking for Python esoterica, there are a few little-known things going on in this line:

print(f"{now:%-I:%M\n%-m/%-d}")

Finding Unicode characters to represent things was a bit of a challenge. I couldn’t find exactly what I need for the right tip of the battery gauge, but it works well enough.

Geektool also does web pages, though in a quick experiment I couldn’t make it do something useful, so I stuck with text mode. There also seem to be old forks of Geektool that offer text colors, which could be cool, but it started to feel a bit off-the-path.

This works great for what it does.