ebook-meta: Add an option to disallow rendered cover of first page fo…

…r EPUB

src/calibre/ebooks/metadata/cli.py

@@ -81,6 +81,9 @@ def config():
     c.add_opt('get_cover', ['--get-cover'],
               help=_('Get the cover from the e-book and save it at as the '
                      'specified file.'))
+    c.add_opt('disallow_rendered_cover', ['--disallow-rendered-cover'], action='store_true', help=_(
+        'For formats like EPUB that use a "default cover" of the first page rendered, disallow such default covers'))
+
     c.add_opt('to_opf', ['--to-opf'],
               help=_('Specify the name of an OPF file. The metadata will '
                      'be written to the OPF file.'))
@@ -182,7 +185,8 @@ def main(args=sys.argv):
         if getattr(opts, pref.name) is not None:
             trying_to_set = True
             break
-    with open(path, 'rb') as stream:
+    from calibre.ebooks.metadata.epub import epub_metadata_settings
+    with open(path, 'rb') as stream, epub_metadata_settings(allow_rendered_cover=not opts.disallow_rendered_cover):
         mi = get_metadata(stream, stream_type, force_read_metadata=True)
     if trying_to_set:
         prints(_('Original metadata')+'::')

src/calibre/ebooks/metadata/epub.py

@@ -10,7 +10,7 @@
 import io
 import os
 import posixpath
-from contextlib import closing, suppress
+from contextlib import closing, contextmanager, suppress
 
 from calibre import CurrentDir
 from calibre.ebooks.metadata.opf import get_metadata as get_metadata_from_opf
@@ -230,6 +230,20 @@ def render_cover(cpage, zf, reader=None):
             return render_html_svg_workaround(cpage, default_log, root=tdir)
 
 
+epub_allow_rendered_cover = True
+
+
+@contextmanager
+def epub_metadata_settings(allow_rendered_cover=epub_allow_rendered_cover):
+    global epub_allow_rendered_cover
+    oarc = epub_allow_rendered_cover
+    epub_allow_rendered_cover = allow_rendered_cover
+    try:
+        yield
+    finally:
+        epub_allow_rendered_cover = oarc
+
+
 def get_cover(raster_cover, first_spine_item, reader):
     zf = reader.archive
 
@@ -241,7 +255,8 @@ def get_cover(raster_cover, first_spine_item, reader):
         except Exception:
             pass
 
-    return render_cover(first_spine_item, zf, reader=reader)
+    if epub_allow_rendered_cover:
+        return render_cover(first_spine_item, zf, reader=reader)
 
 
 def get_metadata(stream, extract_cover=True):