[gnome-shell] ScreenShield: don't animate arrows if the user is idle

[Giovanni Campagna <gcampagna src gnome org>]

commit a9815ae1e9844ac8ae06496981a9ddd23a4a30eb
Author: Giovanni Campagna <gcampagna src gnome org>
Date:   Sat Dec 29 15:24:03 2012 +0100

    ScreenShield: don't animate arrows if the user is idle
    
    If the user is idle, it is very likely the monitor is off too, so let's
    save some power by avoiding animations noone is going to see.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=690857

 js/ui/screenShield.js |   63 ++++++++++++++++++++++++++++++++++++++++++-------
 1 files changed, 54 insertions(+), 9 deletions(-)
---
diff --git a/js/ui/screenShield.js b/js/ui/screenShield.js
index 3c8dd6e..0dfb58d 100644
--- a/js/ui/screenShield.js
+++ b/js/ui/screenShield.js
@@ -38,6 +38,7 @@ const ARROW_DRAG_THRESHOLD = 0.1;
 const N_ARROWS = 3;
 const ARROW_ANIMATION_TIME = 0.6;
 const ARROW_ANIMATION_PEAK_OPACITY = 0.4;
+const ARROW_IDLE_TIME = 30000; // ms
 
 const SUMMARY_ICON_SIZE = 48;
 
@@ -451,6 +452,9 @@ const ScreenShield = new Lang.Class({
         this._updateBackgrounds();
         Main.layoutManager.connect('monitors-changed', Lang.bind(this, this._updateBackgrounds));
 
+        this._arrowAnimationId = 0;
+        this._arrowWatchId = 0;
+        this._arrowActiveWatchId = 0;
         this._arrowContainer = new St.BoxLayout({ style_class: 'screen-shield-arrows',
                                                   vertical: true,
                                                   x_align: Clutter.ActorAlign.CENTER,
@@ -971,16 +975,60 @@ const ScreenShield = new Lang.Class({
             Main.sessionMode.pushMode('lock-screen');
     },
 
+    _startArrowAnimation: function() {
+        this._arrowActiveWatchId = 0;
+
+        if (!this._arrowAnimationId) {
+            this._arrowAnimationId = Mainloop.timeout_add(6000, Lang.bind(this, this._animateArrows));
+            this._animateArrows();
+        }
+
+        if (!this._arrowWatchId)
+            this._arrowWatchId = this.idleMonitor.add_idle_watch(ARROW_IDLE_TIME,
+                                                                 Lang.bind(this, this._pauseArrowAnimation));
+    },
+
+    _pauseArrowAnimation: function() {
+        if (this._arrowAnimationId) {
+            Mainloop.source_remove(this._arrowAnimationId);
+            this._arrowAnimationId = 0;
+        }
+
+        if (!this._arrowActiveWatchId)
+            this._arrowActiveWatchId = this.idleMonitor.add_user_active_watch(Lang.bind(this, 
this._startArrowAnimation));
+    },
+
+    _stopArrowAnimation: function() {
+        if (this._arrowAnimationId) {
+            Mainloop.source_remove(this._arrowAnimationId);
+            this._arrowAnimationId = 0;
+        }
+        if (this._arrowActiveWatchId) {
+            this.idleMonitor.remove_watch(this._arrowActiveWatchId);
+            this._arrowActiveWatchId = 0;
+        }
+        if (this._arrowWatchId) {
+            this.idleMonitor.remove_watch(this._arrowWatchId);
+            this._arrowWatchId = 0;
+        }
+    },
+
+    _checkArrowAnimation: function() {
+        let idleTime = this.idleMonitor.get_idletime();
+
+        if (idleTime < ARROW_IDLE_TIME)
+            this._startArrowAnimation();
+        else
+            this._pauseArrowAnimation();
+    },
+
     _lockScreenShown: function() {
         if (this._dialog && !this._isGreeter) {
             this._dialog.destroy();
             this._dialog = null;
         }
 
-        if (this._arrowAnimationId)
-            Mainloop.source_remove(this._arrowAnimationId);
-        this._arrowAnimationId = Mainloop.timeout_add(6000, Lang.bind(this, this._animateArrows));
-        this._animateArrows();
+        this._checkArrowAnimation();
 
         let motionId = global.stage.connect('captured-event', function(stage, event) {
             if (event.type() == Clutter.EventType.MOTION) {
@@ -1043,12 +1091,9 @@ const ScreenShield = new Lang.Class({
             this._notificationsBox = null;
         }
 
-        this._lockScreenContentsBox.destroy();
+        this._stopArrowAnimation();
 
-        if (this._arrowAnimationId) {
-            Mainloop.source_remove(this._arrowAnimationId);
-            this._arrowAnimationId = 0;
-        }
+        this._lockScreenContentsBox.destroy();
 
         this._hasLockScreen = false;
     },