screenShield: add initial functionality

We are replacing the gnome-screensaver module with with a screen shield
that is part of gnome-shell.

This patch fades out the screen on idle and shows a shield with a background
image when there is activity again. The shield can be removed with a key or
button press.

data/theme/gnome-shell.css

@@ -1717,7 +1717,7 @@ StScrollBar StButton#vhandle:hover
 }
 
 .lightbox {
-    background-color: rgba(0, 0, 0, 0.4);
+    background-color: black;
 }
 
 .flashspot {

js/Makefile.am

@@ -78,6 +78,7 @@ nobase_dist_js_DATA = 	\
 	ui/popupMenu.js		\
 	ui/remoteSearch.js	\
 	ui/runDialog.js		\
+        ui/screenShield.js	\
 	ui/scripting.js		\
 	ui/search.js		\
 	ui/searchDisplay.js	\

js/ui/lightbox.js

@@ -8,6 +8,8 @@ const St = imports.gi.St;
 const Params = imports.misc.params;
 const Tweener = imports.ui.tweener;
 
+const DEFAULT_FADE_FACTOR = 0.4;
+
 /**
  * Lightbox:
  * @container: parent Clutter.Container
@@ -15,7 +17,8 @@ const Tweener = imports.ui.tweener;
  *           - inhibitEvents: whether to inhibit events for @container
  *           - width: shade actor width
  *           - height: shade actor height
- *           - fadeTime: seconds used to fade in/out
+ *           - fadeInTime: seconds used to fade in
+ *           - fadeOutTime: seconds used to fade out
  *
  * Lightbox creates a dark translucent "shade" actor to hide the
  * contents of @container, and allows you to specify particular actors
@@ -38,12 +41,16 @@ const Lightbox = new Lang.Class({
         params = Params.parse(params, { inhibitEvents: false,
                                         width: null,
                                         height: null,
-                                        fadeTime: null
+                                        fadeInTime: null,
+                                        fadeOutTime: null,
+                                        fadeFactor: DEFAULT_FADE_FACTOR
                                       });
 
         this._container = container;
         this._children = container.get_children();
-        this._fadeTime = params.fadeTime;
+        this._fadeInTime = params.fadeInTime;
+        this._fadeOutTime = params.fadeOutTime;
+        this._fadeFactor = params.fadeFactor;
         this.actor = new St.Bin({ x: 0,
                                   y: 0,
                                   style_class: 'lightbox',
@@ -52,6 +59,7 @@ const Lightbox = new Lang.Class({
         container.add_actor(this.actor);
         this.actor.raise_top();
         this.actor.hide();
+        this.shown = false;
 
         this.actor.connect('destroy', Lang.bind(this, this._onDestroy));
 
@@ -93,24 +101,29 @@ const Lightbox = new Lang.Class({
     },
 
     show: function() {
-        if (this._fadeTime) {
+        if (this._fadeInTime) {
             this.actor.opacity = 0;
             Tweener.addTween(this.actor,
-                             { opacity: 255,
+                             { opacity: 255 * this._fadeFactor,
-                               time: this._fadeTime,
+                               time: this._fadeInTime,
-                               transition: 'easeOutQuad'
+                               transition: 'easeOutQuad',
+                               onComplete: Lang.bind(this, function() {
+                                   this.shown = true;
+                               })
                              });
         } else {
-            this.actor.opacity = 255;
+            this.actor.opacity = 255 * this._fadeFactor;
+            this.shown = true;
         }
         this.actor.show();
     },
 
     hide: function() {
-        if (this._fadeTime) {
+        this.shown = false;
+        if (this._fadeOutTime) {
             Tweener.addTween(this.actor,
                              { opacity: 0,
-                               time: this._fadeTime,
+                               time: this._fadeOutTime,
                                transition: 'easeOutQuad',
                                onComplete: Lang.bind(this, function() {
                                    this.actor.hide();

js/ui/main.js

@@ -29,6 +29,7 @@ const LookingGlass = imports.ui.lookingGlass;
 const NetworkAgent = imports.ui.networkAgent;
 const NotificationDaemon = imports.ui.notificationDaemon;
 const WindowAttentionHandler = imports.ui.windowAttentionHandler;
+const ScreenShield = imports.ui.screenShield;
 const Scripting = imports.ui.scripting;
 const ShellDBus = imports.ui.shellDBus;
 const TelepathyClient = imports.ui.telepathyClient;
@@ -52,6 +53,7 @@ let runDialog = null;
 let lookingGlass = null;
 let wm = null;
 let messageTray = null;
+let screenShield = null;
 let notificationDaemon = null;
 let windowAttentionHandler = null;
 let telepathyClient = null;
@@ -211,6 +213,7 @@ function start() {
     panel = new Panel.Panel();
     wm = new WindowManager.WindowManager();
     messageTray = new MessageTray.MessageTray();
+    screenShield = new ScreenShield.ScreenShield();
     keyboard = new Keyboard.Keyboard();
     notificationDaemon = new NotificationDaemon.NotificationDaemon();
     windowAttentionHandler = new WindowAttentionHandler.WindowAttentionHandler();
@@ -670,6 +673,10 @@ function _findModal(actor) {
     return -1;
 }
 
+function isInModalStack(actor) {
+    return _findModal(actor) != -1;
+}
+
 /**
  * pushModal:
  * @actor: #ClutterActor which will be given keyboard focus

js/ui/screenShield.js

@@ -0,0 +1,90 @@
+// -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-
+
+const Clutter = imports.gi.Clutter;
+const Gio = imports.gi.Gio;
+const Lang = imports.lang;
+const Meta = imports.gi.Meta;
+const St = imports.gi.St;
+
+const GnomeSession = imports.misc.gnomeSession;
+const Lightbox = imports.ui.lightbox;
+const LoginDialog = imports.gdm.loginDialog;
+const Main = imports.ui.main;
+
+const SCREENSAVER_SCHEMA = 'org.gnome.desktop.screensaver';
+const LOCK_ENABLED_KEY = 'lock-enabled';
+
+/**
+ * To test screen shield, make sure to kill gnome-screensaver.
+ *
+ * If you are setting org.gnome.desktop.session.idle-delay directly in dconf,
+ * rather than through System Settings, you also need to set
+ * org.gnome.settings-daemon.plugins.power.sleep-display-ac and
+ * org.gnome.settings-daemon.plugins.power.sleep-display-battery to the same value.
+ * This will ensure that the screen blanks at the right time when it fades out.
+ * https://bugzilla.gnome.org/show_bug.cgi?id=668703 explains the dependance.
+ */
+const ScreenShield = new Lang.Class({
+    Name: 'ScreenShield',
+
+    _init: function() {
+        this._presence = new GnomeSession.Presence(Lang.bind(this, function(proxy, error) {
+            this._onStatusChanged(proxy.status);
+        }));
+        this._presence.connectSignal('StatusChanged', Lang.bind(this, function(proxy, senderName, [status]) {
+            this._onStatusChanged(status);
+        }));
+
+        this._settings = new Gio.Settings({ schema: SCREENSAVER_SCHEMA });
+
+        this._group = new St.Group({ x: 0,
+                                     y: 0 });
+        Main.uiGroup.add_actor(this._group);
+        let constraint = new Clutter.BindConstraint({ source: global.stage,
+                                                      coordinate: Clutter.BindCoordinate.POSITION | Clutter.BindCoordinate.SIZE });
+        this._group.add_constraint(constraint);
+        this._group.connect('key-press-event', Lang.bind(this, this._onKeyPressEvent));
+        this._group.connect('button-press-event', Lang.bind(this, this._onButtonPressEvent));
+        this._lightbox = new Lightbox.Lightbox(this._group,
+                                               { inhibitEvents: true, fadeInTime: 10, fadeFactor: 1 });
+        this._background = Meta.BackgroundActor.new_for_screen(global.screen);
+        this._background.hide();
+        Main.uiGroup.add_actor(this._background);
+    },
+
+    _onStatusChanged: function(status) {
+        log ("in _onStatusChanged");
+        if (status == GnomeSession.PresenceStatus.IDLE) {
+            log("session gone idle");
+            this._group.reactive = true;
+            Main.pushModal(this._group);
+            this._lightbox.show();
+        } else {
+            let lightboxWasShown = this._lightbox.shown;
+            this._lightbox.hide();
+            if (lightboxWasShown && this._settings.get_boolean(LOCK_ENABLED_KEY)) {
+                this._background.show();
+                this._background.raise_top();
+            } else {
+                this._popModal();
+            }
+        }
+    },
+
+    _popModal: function() {
+        this._group.reactive = false;
+        if (Main.isInModalStack(this._group))
+            Main.popModal(this._group);
+        this._background.hide();
+    },
+
+    _onKeyPressEvent: function(object, keyPressEvent) {
+        log("in _onKeyPressEvent - lock is enabled: " + this._settings.get_boolean(LOCK_ENABLED_KEY));
+        this._popModal();
+    },
+
+    _onButtonPressEvent: function(object, buttonPressEvent) {
+        log("in _onButtonPressEvent - lock is enabled: " + this._settings.get_boolean(LOCK_ENABLED_KEY));
+        this._popModal();
+    },
+});

js/ui/workspace.js

@@ -301,7 +301,8 @@ const WindowClone = new Lang.Class({
 
         if (!this._zoomLightbox)
             this._zoomLightbox = new Lightbox.Lightbox(Main.uiGroup,
-                                                       { fadeTime: LIGHTBOX_FADE_TIME });
+                                                       { fadeInTime: LIGHTBOX_FADE_TIME,
+                                                         fadeOutTime: LIGHTBOX_FADE_TIME });
         this._zoomLightbox.show();
 
         this._zoomLocalOrig  = new ScaledPoint(this.actor.x, this.actor.y, this.actor.scale_x, this.actor.scale_y);