Quick script to split manga CBZs scanned as two-page spreads so they'll convert with proper page order in Calibre

manga_split.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""A quick helper for splitting manga pages so Calibre doesn't split them for
you and present them in the wrong order.

Takes and produces .cbz files.

Currently assumes first image will be a cover and doesn't split it.
"""

# NOTE: This is a quick hack. Most of the polish is from a template that
#       I start all my quick hacks from.

__author__ = "Stephan Sokolow (deitarion/SSokolow)"
__appname__ = "Manga Page Splitter"
__version__ = "0.1"
__license__ = "MIT"

import logging, os  # noqa: E401
from zipfile import ZipFile

from PIL import Image  # type: ignore

log = logging.getLogger(__name__)

IMAGE_EXTS = Image.registered_extensions()  # Dict[extension, format name]


def process_arg(path):
    log.info("Processing archive %s...", path)
    zbase, zext = os.path.splitext(path)
    outpath = '{}_split{}'.format(zbase, zext)
    cover_seen = False

    with ZipFile(path) as zobj_in, ZipFile(outpath, 'w') as zobj_out:
        for zinfo in sorted(zobj_in.infolist(), key=lambda x: x.filename):
            ibase, iext = os.path.splitext(zinfo.filename)
            iext = iext.lower()

            if zinfo.is_dir():
                log.info("Skipping directory entry: %s", zinfo.filename)
                continue  # ZipInfo.mkdir was only added in Python 3.11
            elif iext in IMAGE_EXTS:
                if not cover_seen:
                    log.info("Copying cover verbatim: %s", zinfo.filename)
                    zobj_out.writestr(zinfo, zobj_in.read(zinfo))
                    cover_seen = True
                    continue

                log.info("Processing image: %s", zinfo.filename)
                im = Image.open(zobj_in.open(zinfo.filename, 'r'))

                fname_right = '{}_1{}'.format(ibase, iext)
                fname_left = '{}_2{}'.format(ibase, iext)
                im_format = IMAGE_EXTS[iext]

                split_point = im.size[0] // 2

                # im.crop will ideally just take a reference to `im`
                #
                # I'm not sure if this will duplicate the column of pixels at
                # split_point, but it doesn't matter
                page_right = im.crop((split_point, 0, im.size[0], im.size[1]))
                page_right.save(zobj_out.open(fname_right, 'w'), im_format)
                page_right.close()

                page_left = im.crop((0, 0, split_point, im.size[1]))
                page_left.save(zobj_out.open(fname_left, 'w'), im_format)
                page_left.close()

            else:
                log.info("Copying non-image verbatim: %s", zinfo.filename)
                zobj_out.writestr(zinfo, zobj_in.read(zinfo))


def main():
    """The main entry point, compatible with setuptools entry points."""
    from argparse import ArgumentParser, RawDescriptionHelpFormatter
    parser = ArgumentParser(formatter_class=RawDescriptionHelpFormatter,
        description=__doc__.replace('\r\n', '\n').split('\n--snip--\n')[0])
    parser.add_argument('-V', '--version', action='version',
        version="%%(prog)s v%s" % __version__)
    parser.add_argument('-v', '--verbose', action="count",
        default=3, help="Increase the verbosity. Use twice for extra effect.")
    parser.add_argument('-q', '--quiet', action="count",
        default=0, help="Decrease the verbosity. Use twice for extra effect.")
    parser.add_argument('path', action="store", nargs="+",
        help="Path to operate on")

    args = parser.parse_args()

    # Set up clean logging to stderr
    log_levels = [logging.CRITICAL, logging.ERROR, logging.WARNING,
                  logging.INFO, logging.DEBUG]
    args.verbose = min(args.verbose - args.quiet, len(log_levels) - 1)
    args.verbose = max(args.verbose, 0)
    logging.basicConfig(level=log_levels[args.verbose],
                        format='%(levelname)s: %(message)s')

    for path in args.path:
        process_arg(path)


if __name__ == '__main__':  # pragma: nocover
    main()

# vim: set sw=4 sts=4 expandtab :