Make preserving of tag structure when splitting optional

src/calibre/ebooks/epub/__init__.py

@@ -123,6 +123,8 @@ to auto-generate a Table of Contents.
            help=_('The base font size in pts. Default is %defaultpt. Set to 0 to disable rescaling of fonts.'))
     layout('remove_paragraph_spacing', ['--remove-paragraph-spacing'], default=True,
            help=_('Remove spacing between paragraphs. Will not work if the source file forces inter-paragraph spacing.'))
+    layout('preserve_tag_structure', ['--preserve-tag-structure'], default=False,
+           help=_('Preserve the HTML tag structure while splitting large HTML files. This is only neccessary if the HTML files contain CSS that uses sibling selectors. Enabling this greatly slows down processing of large HTML files.'))
     
     c.add_opt('show_opf', ['--show-opf'], default=False, group='debug',
               help=_('Print generated OPF file to stdout'))

src/calibre/ebooks/epub/from_any.py

@@ -34,7 +34,6 @@ def mobi2opf(path, tdir, opts):
     reader = MobiReader(path)
     reader.extract_content(tdir)
     files = list(walk(tdir))
-    opts.dont_preserve_structure = True
     opts.encoding = 'utf-8'
     for f in files:
         if f.lower().endswith('.opf'):

src/calibre/ebooks/epub/split.py

@@ -382,7 +382,7 @@ def split(pathtoopf, opts, stylesheet_map):
                     item.set('href', item.get('href').replace('&', '%26'))
                 html_files.append(f)
         changes = []
-        always_remove = getattr(opts, 'dont_preserve_structure', False)
+        always_remove = not opts.preserve_tag_structure
         for f in html_files:
             if os.stat(content(f)).st_size > opts.profile.flow_size:
                 try:

src/calibre/gui2/dialogs/epub.ui

@@ -77,7 +77,7 @@
      <item>
       <widget class="QStackedWidget" name="stack" >
        <property name="currentIndex" >
-        <number>0</number>
+        <number>1</number>
        </property>
        <widget class="QWidget" name="metadata_page" >
         <layout class="QGridLayout" name="gridLayout_4" >
@@ -89,6 +89,36 @@
               <string>Book Cover</string>
              </property>
              <layout class="QGridLayout" name="_2" >
+              <item row="0" column="0" >
+               <layout class="QHBoxLayout" name="_3" >
+                <item>
+                 <widget class="ImageView" name="cover" >
+                  <property name="text" >
+                   <string/>
+                  </property>
+                  <property name="pixmap" >
+                   <pixmap resource="../images.qrc" >:/images/book.svg</pixmap>
+                  </property>
+                  <property name="scaledContents" >
+                   <bool>true</bool>
+                  </property>
+                  <property name="alignment" >
+                   <set>Qt::AlignCenter</set>
+                  </property>
+                 </widget>
+                </item>
+               </layout>
+              </item>
+              <item row="2" column="0" >
+               <widget class="QCheckBox" name="opt_prefer_metadata_cover" >
+                <property name="text" >
+                 <string>Use cover from &amp;source file</string>
+                </property>
+                <property name="checked" >
+                 <bool>true</bool>
+                </property>
+               </widget>
+              </item>
               <item row="1" column="0" >
                <layout class="QVBoxLayout" name="_4" >
                 <property name="spacing" >
@@ -140,36 +170,6 @@
                 </item>
                </layout>
               </item>
-              <item row="2" column="0" >
-               <widget class="QCheckBox" name="opt_prefer_metadata_cover" >
-                <property name="text" >
-                 <string>Use cover from &amp;source file</string>
-                </property>
-                <property name="checked" >
-                 <bool>true</bool>
-                </property>
-               </widget>
-              </item>
-              <item row="0" column="0" >
-               <layout class="QHBoxLayout" name="_3" >
-                <item>
-                 <widget class="ImageView" name="cover" >
-                  <property name="text" >
-                   <string/>
-                  </property>
-                  <property name="pixmap" >
-                   <pixmap resource="../images.qrc" >:/images/book.svg</pixmap>
-                  </property>
-                  <property name="scaledContents" >
-                   <bool>true</bool>
-                  </property>
-                  <property name="alignment" >
-                   <set>Qt::AlignCenter</set>
-                  </property>
-                 </widget>
-                </item>
-               </layout>
-              </item>
              </layout>
              <zorder>opt_prefer_metadata_cover</zorder>
              <zorder></zorder>
@@ -449,6 +449,13 @@
              </property>
             </widget>
            </item>
+           <item row="3" column="0" >
+            <widget class="QCheckBox" name="opt_preserve_tag_structure" >
+             <property name="text" >
+              <string>Preserve &amp;tag structure when splitting</string>
+             </property>
+            </widget>
+           </item>
           </layout>
          </item>
          <item>