dmi.py

#!/usr/bin/env python3

import sys, shutil
from PIL import Image
from PIL.PngImagePlugin import PngInfo

def split(fname):
    image = Image.open(f"{fname}.dmi")
    if 'Description' not in image.info:
        return
    metadata = image.info['Description']
    line_iter = iter(metadata.splitlines())
    assert next(line_iter) == "# BEGIN DMI"
    with open(f"{fname}.txt", "w") as f:
        for each in line_iter:
            if each.startswith("# END DMI"):
                break
            f.write(f"{each}\n")
    shutil.copy(f"{fname}.dmi", f"{fname}.png")
    print(f"Split {fname}.png and {fname}.txt")

def compose(fname):
    with open(f"{fname}.txt") as f:
        dmi = "# BEGIN DMI\n" + f.read().replace("    ", "\t")

    pnginfo = PngInfo()
    pnginfo.add_text('Description', dmi, zip=True)
    Image.open(f"{fname}.png").save(f"{fname}.dmi", 'png', optimize=True, pnginfo=pnginfo)
    print(f"Built {fname}.dmi")

for fname in sys.argv[1:]:
    if fname.endswith('.dmi'):
        split(fname[:-4])
    elif fname.endswith('.png') or fname.endswith('.txt'):
        compose(fname[:-4])