How do I write a Unity system indicator in Python?

Background:

• This is NOT for application-indicators but system-indicators.

  

  Picture from: https://wiki.ubuntu.com/DesktopExperienceTeam/ApplicationIndicators

• The objective is to show indicator-sysmonitor in Greeter/Lock/Ubiquity screens. There is a work around in:

  How to make indicator-sysmonitor as a default indicator on the login screen

C Original Code: (working fine)

• I already get one working in C language, see my other question:

  How to develop a System Indicator for Unity?

  However, indicator-sysmonitor is already developed in Python as many other application indicators. I don't like the idea that developers obliged to port their projects to C or write a Python-C proxy if they want to show the indicator in greeter/lock/ubiquity screens. Instead, making indicator-sysmonitor creates a system indicator directly from python would be the best solution (no workarounds, and it will be a generic solution for all python projects that currently using appindicator).

Python Code: (My failed trial to port c code to python)

• I'm struggling to port it into Python. Here is my current code which doesn't work. It does create DBus object for both Menu & Actions. It is listed in the XFCE indicators plugin. But not showed on the panel.

  /usr/lib/indicator-test/indicator-test-service

  #!/usr/bin/python2
  
  import os
  import sys
  
  import gi
  from gi.repository import Gio, GLib
  
  APPLICATION_ID = 'local.sneetsher.indicator.test'
  DBUS_MENU_PATH = '/local/sneetsher/indicator/test/desktop'
  DBUS_ACTION_PATH = '/local/sneetsher/indicator/test'
  
  def callback():
      print ok
  
  def quit_callback(notification, loop):
      global connection
      global exported_action_group_id
      global exported_menu_model_id
  
      connection.unexport_action_group (exported_action_group_id)
      connection.unexport_menu_model (exported_menu_model_id)
  
      loop.quit()
  
  def cancel (notification, action, data):
      if action == "cancel":
          print "Cancel"
      else:
          print "That should not have happened (cancel)!"
  
  def bus_acquired(bus, name):
      # menu
      submenu = Gio.Menu()
      submenu.append("Show", "show")
      item = Gio.MenuItem.new(None, "_header")
      item.set_attribute([("x-canonical-type","s","com.canonical.indicator.root")])
      item.set_submenu(submenu)
      menu = Gio.Menu()
      menu.append_item (item)
  
      actions = Gio.SimpleActionGroup.new()
      action1 = Gio.SimpleAction.new("_header", None)
      actions.insert(action1)
      action2 = Gio.SimpleAction.new('show', None)
      actions.insert(action2)
      action2.connect("activate",callback)
  
      global connection
      connection = bus
  
      global exported_action_group_id
      exported_action_group_id = connection.export_action_group(DBUS_ACTION_PATH, actions)
  
      global exported_menu_model_id
      exported_menu_model_id = connection.export_menu_model(DBUS_MENU_PATH, menu)
  
  def setup ():
      #bus connection
      Gio.bus_own_name(Gio.BusType.SESSION, APPLICATION_ID, 0, bus_acquired, None, None)
  
  if __name__ == '__main__':
  
      connection = None
      exported_menu_model_id = 0
      exported_action_group_id = 0
      password = ""
  
      loop = GLib.MainLoop()
      setup ()
  
      loop.run()
  

  local.sneetsher.indicator.test

  [Indicator Service]
  Name=indicator-test
  ObjectPath=/local/sneetsher/indicator/test
  
  [desktop]
  ObjectPath=/local/sneetsher/indicator/test/desktop
  
  [desktop_greeter]
  ObjectPath=/local/sneetsher/indicator/test/desktop
  
  [desktop_lockscreen]
  ObjectPath=/local/sneetsher/indicator/test/desktop
  

  local.sneetsher.indicator.test.service

  [D-BUS Service]
  Name=local.sneetsher.indicator.test
  Exec=/usr/lib/indicator-test/indicator-test-service
  

  90_unity-greeter.gschema.override

  [com.canonical.unity-greeter]
  indicators=['ug-accessibility', 'com.canonical.indicator.keyboard', 'com.canonical.indicator.session', 'com.canonical.indicator.datetime', 'com.canonical.indicator.power', 'com.canonical.indicator.sound', 'local.sneetsher.indicator.test', 'application']
  

Question:

I expect the reason why, I didn't create the menu structure or its meta (pseudo items like _header) as they are in the original C code.

Could anyone make a working port of this system indicator code in C to Python?

I've just uploaded a raw "working" Python example ported from the @user.dz C example. Here's the source code repository:

• github.com/marto-ales/systemindicator

I will update it as I go along but any contribution is welcome.

Thanks for the useful information!

Ported source code of the main script. Note: It is initial copy as link may broke in future. For complete package and last update, follow the link above.

#!/usr/bin/python3
import sys
import os
import logging
import logging.handlers
logger = logging.getLogger('LoginHelper')
logger.setLevel(logging.DEBUG)
handler = logging.handlers.SysLogHandler(address = '/dev/log')
logger.addHandler(handler)
logger.debug("Login-Helper: Start")
os.environ["DISPLAY"] = ":0"

import gi
gi.require_version('Gtk', '3.0')
from gi.repository import Gtk
from gi.repository import Gio
from gi.repository import GLib


class LoginHelperIndicator():

  def __init__(self, dbus_name, dbus_path):
    self.dbus_name = dbus_name
    self.dbus_path = dbus_path
    self.actions = Gio.SimpleActionGroup()
    self.menu = Gio.Menu()
    self.actions_export_id = 0
    self.menu_export_id = 0



  def activate_about (self, action, parameter):
    # gtk_show_about_dialog(NULL,
    #                       "program-name", PROJECT_NAME,
    #                       "title", "About " PROJECT_NAME,
    #                       "version", PROJECT_VERSION_MAJOR "." PROJECT_VERSION_MINOR,
    #                       "license_type", GTK_LICENSE_GPL_3_0,
    #                       "wrap_license", TRUE,
    #                       "website", "https://github.com/sneetsher/mysystemindicator",
    #                       "website_label", "https://github.com/sneetsher/mysystemindicator",
    #                       "logo_icon_name", "indicator-" SHORT_NAME,
    #                       NULL);
    # g_message ("showing about dialog");
    pass

  def activate_private (self, action, parameter):
    #g_message ("clicked private menu entry");
    pass

  def activate_exit (self, action, parameter):
    #g_message ("exit the program");
    Gtk.main_quit()

  def on_bus_acquired (self, connection, name):
    logger.debug ('Bus acquired: ' + str(connection))
    error = None
    item = Gio.MenuItem()
    submenu = Gio.Menu()

    action_state = GLib.Variant("a{sv}", {
      'label': GLib.Variant("s", "Login-helper"),
      'icon':  GLib.Variant("s", "indicator-loginhelper"),
      'accessible-desc': GLib.Variant("s", "Login Helper indicator")
    })
    self.actions.add_action(Gio.SimpleAction.new_stateful("_header", None, action_state))
    about_action = Gio.SimpleAction.new("about", None)
    about_action.connect("activate", self.activate_about)
    self.actions.add_action(about_action)
    private_action = Gio.SimpleAction.new("private", None)
    private_action.connect("activate", self.activate_private)
    self.actions.add_action(private_action)
    exit_action = Gio.SimpleAction.new("exit", None)
    exit_action.connect("activate", self.activate_exit)
    self.actions.add_action(exit_action)

    submenu.append("About", "indicator.about")
    submenu.append("Exit", "indicator.exit")
    item = Gio.MenuItem().new(None, "indicator._header")
    item.set_attribute_value("x-canonical-type", GLib.Variant("s", "com.canonical.indicator.root"))
    item.set_submenu(submenu)

    self.menu = Gio.Menu.new()
    self.menu.append_item(item)

    self.actions_export_id = connection.export_action_group(self.dbus_path, self.actions)
    if self.actions_export_id == 0:
      #g_warning ("cannot export action group: %s", error->message);
      #g_error_free (error);
      return

    self.menu_export_id = connection.export_menu_model(self.dbus_path + "/greeter", self.menu)
    if self.menu_export_id == 0:
      #g_warning ("cannot export menu: %s", error->message);
      #g_error_free (error);
      return


  def on_name_lost (self, connection, name):
    if self.actions_export_id:
      connection.unexport_action_group(self.actions_export_id)

    if (self.menu_export_id):
      connection.unexport_menu_model(self.menu_export_id)


if __name__ == '__main__':

  logger.debug('Login-Helper: Initializing Login Helper Indicator')

  res_gtk = Gtk.init(sys.argv)
  indicator = LoginHelperIndicator('com.canonical.indicator.loginhelper', '/com/canonical/indicator/loginhelper')

  logger.debug ('Login-Helper: Res_gtk: ' + str(res_gtk))
  res_own = Gio.bus_own_name(Gio.BusType.SESSION,
                indicator.dbus_name,
                Gio.BusNameOwnerFlags.NONE,
                indicator.on_bus_acquired,
                None,
                indicator.on_name_lost)
  logger.debug ('Login-Helper: Res_own: ' + str(res_own))

  Gtk.main()

  exit(0)