screensaver: factor out a ScreenSaverProxy helper class

This class will be shared between StatusMenu and the upcoming
AutomountManager classes.

https://bugzilla.gnome.org/show_bug.cgi?id=653520

js/Makefile.am

@@ -10,6 +10,7 @@ nobase_dist_js_DATA = 	\
 	misc/history.js		\
 	misc/modemManager.js	\
 	misc/params.js		\
+	misc/screenSaver.js     \
 	misc/util.js		\
 	perf/core.js		\
 	ui/altTab.js		\

js/misc/screenSaver.js

@@ -0,0 +1,59 @@
+/* -*- mode: js2; js2-basic-offset: 4; indent-tabs-mode: nil -*- */
+
+const DBus = imports.dbus;
+const Lang = imports.lang;
+const Signals = imports.signals;
+
+const ScreenSaverIface = {
+    name: 'org.gnome.ScreenSaver',
+    methods: [{ name: 'GetActive',
+                inSignature: '',
+                outSignature: 'b' },
+              { name: 'Lock',
+                inSignature: '' },
+              { name: 'SetActive',
+                inSignature: 'b' }],
+    signals: [{ name: 'ActiveChanged',
+                inSignature: 'b' }]
+};
+
+function ScreenSaverProxy() {
+    this._init();
+}
+
+ScreenSaverProxy.prototype = {
+    _init: function() {
+        DBus.session.proxifyObject(this,
+                                   'org.gnome.ScreenSaver',
+                                   '/org/gnome/ScreenSaver');
+
+        DBus.session.watch_name('org.gnome.ScreenSaver',
+                                false, // do not launch a name-owner if none exists
+                                Lang.bind(this, this._onSSAppeared),
+                                Lang.bind(this, this._onSSVanished));
+
+        this.connect('ActiveChanged',
+                     Lang.bind(this, this._onActiveChanged));
+    },
+
+    _onSSAppeared: function(owner) {
+        this.GetActiveRemote(Lang.bind(this, function(isActive) {
+            this._screenSaverActive = isActive;
+        }))
+    },
+
+    _onSSVanished: function(oldOwner) {
+        this._screenSaverActive = false;
+    },
+
+    _onActiveChanged: function(object, isActive) {
+        this._screenSaverActive = isActive;
+        this.emit('active-changed', this._screenSaverActive);
+    },
+
+    getActive: function() {
+        return this._screenSaverActive;
+    }
+};
+DBus.proxifyPrototype(ScreenSaverProxy.prototype, ScreenSaverIface);
+Signals.addSignalMethods(ScreenSaverProxy.prototype);

js/ui/statusMenu.js

@@ -14,24 +14,14 @@ const GnomeSession = imports.misc.gnomeSession;
 const Main = imports.ui.main;
 const PanelMenu = imports.ui.panelMenu;
 const PopupMenu = imports.ui.popupMenu;
+const ScreenSaver = imports.misc.screenSaver;
 const Util = imports.misc.util;
 
-const BUS_NAME = 'org.gnome.ScreenSaver';
-const OBJECT_PATH = '/org/gnome/ScreenSaver';
-
 const LOCKDOWN_SCHEMA = 'org.gnome.desktop.lockdown';
 const DISABLE_USER_SWITCH_KEY = 'disable-user-switching';
 const DISABLE_LOCK_SCREEN_KEY = 'disable-lock-screen';
 const DISABLE_LOG_OUT_KEY = 'disable-log-out';
 
-const ScreenSaverInterface = {
-    name: BUS_NAME,
-    methods: [ { name: 'Lock', inSignature: '' },
-               { name: 'SetActive', inSignature: 'b' }]
-};
-
-let ScreenSaverProxy = DBus.makeProxyClass(ScreenSaverInterface);
-
 // Adapted from gdm/gui/user-switch-applet/applet.c
 //
 // Copyright (C) 2004-2005 James M. Cape <jcape@ignore-your.tv>.
@@ -63,7 +53,7 @@ StatusMenuButton.prototype = {
         this._account_mgr = Tp.AccountManager.dup()
 
         this._upClient = new UPowerGlib.Client();
-        this._screenSaverProxy = new ScreenSaverProxy(DBus.session, BUS_NAME, OBJECT_PATH);
+        this._screenSaverProxy = new ScreenSaver.ScreenSaverProxy();
         this.actor.connect('destroy', Lang.bind(this, this._onDestroy));
 
         this._iconBox = new St.Bin();