tag browser visibility: changed name and added operations

src/calibre/gui2/tag_browser/ui.py

@@ -435,10 +435,14 @@ class TagBrowserMixin(object):  # {{{
     def drag_drop_finished(self, ids):
         self.library_view.model().refresh_ids(ids)
 
-    def change_tb_category_visibility(self, category, operation):
+    def tb_category_visibility(self, category, operation):
         '''
-        Hide or show categories in the tag browser. 'category' is the lookup key
+        Hide or show categories in the tag browser. 'category' is the lookup key.
-        to show or hide. Set operation == 'show' or 'hide' as needed.
+        Operation can be:
+        - 'show' to show the category in the tag browser
+        - 'hide' to hide the category
+        - 'toggle' to invert its visibility
+        - 'is_visible' returns 'True' if the category is currently visible, False otherwise
         '''
         if category not in self.tags_view.model().categories:
             raise ValueError(_('change_tb_category_visibility: category %s does not exist') % category)
@@ -447,6 +451,13 @@ class TagBrowserMixin(object):  # {{{
             cats.add(category)
         elif operation == 'show':
             cats.discard(category)
+        elif operation == 'toggle':
+            if category in cats:
+                cats.remove(category)
+            else:
+                cats.add(category)
+        elif operation == 'is_visible':
+            return category not in cats
         else:
             raise ValueError(_('change_tb_category_visibility: invalid operation %s') % operation)
         self.library_view.model().db.new_api.set_pref('tag_browser_hidden_categories', list(cats))