Allow viewer plugins to customize the viewer's UI

src/calibre/customize/__init__.py

@@ -726,5 +726,21 @@ class ViewerPlugin(Plugin): # {{{
         '''
         pass
 
+    def customize_ui(self, ui):
+        '''
+        This method is called once when the viewer is created. Use it to make
+        any customizations you want to the viewer's user interface. For
+        example, you can modify the toolbars via ui.tool_bar and ui.tool_bar2.
+        '''
+        pass
+    def customize_context_menu(self, menu, event, hit_test_result):
+        '''
+        This method is called every time the context (right-click) menu is
+        shown. You can use it to customize the context menu. event is the
+        context menu event and hit_test_result is the QWebHitTestResult for this
+        event in the currently loaded document.
+        '''
+        pass
+
 # }}}
 

src/calibre/gui2/viewer/documentview.py

@@ -702,6 +702,8 @@ class DocumentView(QWebView):  # {{{
             menu.addSeparator()
             menu.addAction(self.manager.action_quit)
 
+        for plugin in self.document.all_viewer_plugins:
+            plugin.customize_context_menu(menu, ev, r)
         menu.exec_(ev.globalPos())
 
     def inspect(self):

src/calibre/gui2/viewer/main.py

@@ -359,6 +359,8 @@ class EbookViewer(MainWindow, Ui_EbookViewer):
                 # continue to function even when the toolbars are hidden
                 self.addAction(action)
 
+        for plugin in self.view.document.all_viewer_plugins:
+            plugin.customize_ui(self)
         self.view.document.settings_changed.connect(self.settings_changed)
 
         self.restore_state()