Prints .lua.png files exported from PICO-8 on a DevTerm

p8_devterm_printwatcher.py

# The PICO-8 text printer for the ClockworkPi DevTerm!
#
# This Python script allows you to print text directly from the PICO-8 source
# code editor. The script runs in the background and watches for you to execute
# the "EXPORT FILE.LUA.PNG" command. It does some light processing of the
# generated image file, then sends it to DevTerm's thermal printer.
#
# This is mostly just a joke/hack for the purposes of this tweet:
#   https://twitter.com/dan_sanderson/status/1434253649266364417?s=20
#
# To set up DevTerm printing via CUPS:
#   sudo apt -y install libcups2-dev   
#   git clone https://github.com/clockworkpi/DevTerm.git
#   cd DevTerm/devterm_thermal_printer_cups
#   make
#   sudo make install
#   lpoptions -d devterm_printer
#
# This script uses ImageMagick to convert the color Lua code listing to black and
# white. To install it:
#    sudo apt install imagemagick
#
# This script needs Python Watchdog. To install it:
#    pip3 install watchdog
#
# To run the watcher script:
#    python3 p8_devterm_printwatcher.py
#
# To print code from a PICO-8 cart, within PICO-8, export the .lua.png file:
#    EXPORT MYFILE.LUA.PNG

import os.path
import subprocess
import time
from watchdog.events import PatternMatchingEventHandler
from watchdog.observers import Observer

PICO8_CARTS_DIR = os.path.expanduser(
    '~/.lexaloffle/pico-8/carts')
TMP_DIR = '/tmp'
IMAGEMAGICK_CONVERT_CMD = '/usr/bin/convert'

# Avoids double-triggering from how PICO-8 updates files
cooldown = {}


class Handler(PatternMatchingEventHandler):
    @staticmethod
    def on_modified(event):
        if time.time() - cooldown.get(event.src_path, 0) < 2:
            return
        cooldown[event.src_path] = time.time()
        
        if not event.src_path.endswith('.lua.png'):
            return
        tmp_name = os.path.join(TMP_DIR, os.path.basename(event.src_path))
        print('Printing ' + event.src_path)
        args = [
            IMAGEMAGICK_CONVERT_CMD,
            event.src_path,
            '-fill', '#FFFFFF',
            '-opaque', '#1D2B53',
            '-threshold', '99%',
            '-scale', '180%',
            tmp_name
        ]
        subprocess.run(args)
        subprocess.run([
            'lp',
            '-o', 'scaling=0',
            tmp_name
        ])
        p = subprocess.Popen(['lp'], stdin=subprocess.PIPE)
        p.stdin.write(b'\n\n\n\n\n\n\n\n')
        p.communicate()
        p.stdin.close()

        
if __name__ == "__main__":
    event_handler = Handler(patterns=['*.lua.png'], ignore_directories=True)
    observer = Observer()
    observer.schedule(event_handler, PICO8_CARTS_DIR, recursive=True)
    observer.start()
    try:
        while True:
            time.sleep(1)
    finally:
        observer.stop()
        observer.join()