New option to hide empty categories in Tag Browser (Preferences->Look & Feel->Tag Browser)

Merge branch 'master' of https://github.com/cbhaley/calibre

src/calibre/gui2/__init__.py

@@ -115,6 +115,7 @@ defs['auto_add_auto_convert'] = True
 defs['auto_add_everything'] = False
 defs['ui_style'] = 'calibre' if iswindows or isosx else 'system'
 defs['tag_browser_old_look'] = False
+defs['tag_browser_hide_empty_categories'] = False
 defs['book_list_tooltips'] = True
 defs['bd_show_cover'] = True
 defs['bd_overlay_cover_size'] = False

src/calibre/gui2/preferences/look_feel.py

@@ -159,6 +159,7 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
                     'calibre')])
         r('book_list_tooltips', gprefs)
         r('tag_browser_old_look', gprefs, restart_required=True)
+        r('tag_browser_hide_empty_categories', gprefs)
         r('bd_show_cover', gprefs)
         r('bd_overlay_cover_size', gprefs)
         r('cover_grid_width', gprefs)

src/calibre/gui2/preferences/look_feel.ui

@@ -898,6 +898,19 @@ then the tags will be displayed each on their own line.</string>
          </property>
         </widget>
        </item>
+       <item row="8" column="0" colspan="2">
+        <widget class="QCheckBox" name="opt_tag_browser_hide_empty_categories">
+         <property name="text">
+          <string>Hi&amp;de empty categories (columns) in the tag browser</string>
+         </property>
+         <property name="toolTip">
+          <string>When checked, calibre will automatically hide any category
+ (a column, custom or standard) that has no items to show. For example, some
+ categories might not have values when using virtual libraries. Checking this
+ box will cause these empty categories to be hidden.</string>
+         </property>
+        </widget>
+       </item>
        <item row="1" column="1">
         <widget class="QComboBox" name="opt_tags_browser_partition_method">
          <property name="toolTip">

src/calibre/gui2/tag_browser/model.py

@@ -665,6 +665,8 @@ class TagsModel(QAbstractItemModel):  # {{{
         for node in self.root_item.children:
             key = node.category_key
             if key in self.row_map:
+                if self.prefs['tag_browser_hide_empty_categories'] and len(node.child_tags()) == 0:
+                    continue;
                 if self.hidden_categories:
                     if key in self.hidden_categories:
                         continue