EPUBの見開き方向を right-to-left (縦書き用) に変える

epub_pagertl.py

import sys
from zipfile import ZipFile
import lxml.etree as et

for path in sys.argv[1:]:
    zf = ZipFile(path, mode='a')

    with zf.open('OEBPS/content.opf', mode='r') as f:
        doc = et.parse(f)

    spine = doc.find('.//{http://www.idpf.org/2007/opf}spine')
    print(spine.get("page-progression-direction"))
    spine.set("page-progression-direction", "rtl")

    with zf.open('OEBPS/content.opf', mode='w') as f:
        f.write(et.tostring(doc, encoding='utf-8', pretty_print=True))

    zf.close()