MOBI Output: Make generating the navpoints for chapter to chapter skipping more robust. Also geenrate navpoints for every item in the TOC, not just the items at the deepest level.

src/calibre/ebooks/mobi/output.py

@@ -50,6 +50,13 @@ class MOBIOutput(OutputFormatPlugin):
             help=_('When adding the Table of Contents to the book, add it at the start of the '
                 'book instead of the end. Not recommended.')
         ),
+        OptionRecommendation(name='mobi_navpoints_only_deepest',
+            recommended_value=False,
+            help=_('When adding navpoints for the chapter-to-chapter'
+                ' navigation on the kindle, use only the lowest level '
+                'of items in the TOC, instead of items at every level.')
+        ),
+
         OptionRecommendation(name='kindlegen',
             recommended_value=False,
             help=('Use kindlegen (must be in your PATH) to generate the'

src/calibre/ebooks/mobi/writer.py

@@ -1231,6 +1231,9 @@ class MobiWriter(object):
             self._oeb.logger.info('  Compressing markup content...')
         data, overlap = self._read_text_record(text)
 
+        if not self.opts.mobi_periodical:
+            self._flatten_toc()
+
         # Evaluate toc for conformance
         if self.opts.mobi_periodical :
             self._oeb.logger.info('  MOBI periodical specified, evaluating TOC for periodical conformance ...')
@@ -1697,6 +1700,32 @@ class MobiWriter(object):
 
     # Index {{{
 
+    def _flatten_toc(self):
+        '''
+        Flatten and re-order entries in TOC so that chapter to chapter jumping
+        never fails on the Kindle.
+        '''
+        from calibre.ebooks.oeb.base import TOC
+        items = list(self._oeb.toc.iterdescendants())
+        if self.opts.mobi_navpoints_only_deepest:
+            items = [i for i in items if i.depth == 1]
+        offsets = {i:self._id_offsets.get(i.href, -1) for i in items if i.href}
+        items = [i for i in items if offsets[i] > -1]
+        items.sort(key=lambda i:offsets[i])
+        filt = []
+        seen = set()
+        for i in items:
+            off = offsets[i]
+            if off in seen: continue
+            seen.add(off)
+            filt.append(i)
+        items = filt
+        newtoc = TOC()
+        for c, i in enumerate(items):
+            newtoc.add(i.title, i.href, play_order=c+1, id=str(c),
+                    klass='chapter')
+        self._oeb.toc = newtoc
+
     def _generate_index(self):
         self._oeb.log('Generating INDX ...')
         self._primary_index_record = None

src/calibre/gui2/convert/mobi_output.py

@@ -25,7 +25,8 @@ class PluginWidget(Widget, Ui_Form):
         Widget.__init__(self, parent,
                 ['prefer_author_sort', 'rescale_images', 'toc_title',
                     'mobi_ignore_margins', 'mobi_toc_at_start',
-                'dont_compress', 'no_inline_toc', 'masthead_font','personal_doc']
+                'dont_compress', 'no_inline_toc',
+                'masthead_font','personal_doc', 'mobi_navpoints_only_deepest']
                 )
         from calibre.utils.fonts import fontconfig
         self.db, self.book_id = db, book_id

src/calibre/gui2/convert/mobi_output.ui

@@ -55,7 +55,7 @@
      </property>
     </widget>
    </item>
-   <item row="8" column="0" colspan="2">
+   <item row="9" column="0" colspan="2">
     <widget class="QGroupBox" name="groupBox">
      <property name="title">
       <string>Kindle options</string>
@@ -101,7 +101,7 @@
      </layout>
     </widget>
    </item>
-   <item row="9" column="0">
+   <item row="10" column="0">
     <spacer name="verticalSpacer_2">
      <property name="orientation">
       <enum>Qt::Vertical</enum>
@@ -128,6 +128,13 @@
      </property>
     </widget>
    </item>
+   <item row="7" column="0" colspan="2">
+    <widget class="QCheckBox" name="opt_mobi_navpoints_only_deepest">
+     <property name="text">
+      <string>Use only &amp;lowest level of items in the TOC for chapter-to-chapter navigation</string>
+     </property>
+    </widget>
+   </item>
   </layout>
  </widget>
  <resources/>