Source: trackers/TrackerTask.js

  1. (function() {
  2.   /**
  3.    * TrackerTask utility.
  4.    * @constructor
  5.    * @extends {tracking.EventEmitter}
  6.    */
  7.   tracking.TrackerTask = function(tracker) {
  8.     tracking.TrackerTask.base(this, 'constructor');
  10.     if (!tracker) {
  11.       throw new Error('Tracker instance not specified.');
  12.     }
  14.     this.setTracker(tracker);
  15.   };
  17.   tracking.inherits(tracking.TrackerTask, tracking.EventEmitter);
  19.   /**
  20.    * Holds the tracker instance managed by this task.
  21.    * @type {tracking.Tracker}
  22.    * @private
  23.    */
  24.   tracking.TrackerTask.prototype.tracker_ = null;
  26.   /**
  27.    * Holds if the tracker task is in running.
  28.    * @type {boolean}
  29.    * @private
  30.    */
  31.   tracking.TrackerTask.prototype.running_ = false;
  33.   /**
  34.    * Gets the tracker instance managed by this task.
  35.    * @return {tracking.Tracker}
  36.    */
  37.   tracking.TrackerTask.prototype.getTracker = function() {
  38.     return this.tracker_;
  39.   };
  41.   /**
  42.    * Returns true if the tracker task is in running, false otherwise.
  43.    * @return {boolean}
  44.    * @private
  45.    */
  46.   tracking.TrackerTask.prototype.inRunning = function() {
  47.     return this.running_;
  48.   };
  50.   /**
  51.    * Sets if the tracker task is in running.
  52.    * @param {boolean} running
  53.    * @private
  54.    */
  55.   tracking.TrackerTask.prototype.setRunning = function(running) {
  56.     this.running_ = running;
  57.   };
  59.   /**
  60.    * Sets the tracker instance managed by this task.
  61.    * @return {tracking.Tracker}
  62.    */
  63.   tracking.TrackerTask.prototype.setTracker = function(tracker) {
  64.     this.tracker_ = tracker;
  65.   };
  67.   /**
  68.    * Emits a `run` event on the tracker task for the implementers to run any
  69.    * child action, e.g. `requestAnimationFrame`.
  70.    * @return {object} Returns itself, so calls can be chained.
  71.    */
  72.   tracking.TrackerTask.prototype.run = function() {
  73.     var self = this;
  75.     if (this.inRunning()) {
  76.       return;
  77.     }
  79.     this.setRunning(true);
  80.     this.reemitTrackEvent_ = function(event) {
  81.       self.emit('track', event);
  82.     };
  83.     this.tracker_.on('track', this.reemitTrackEvent_);
  84.     this.emit('run');
  85.     return this;
  86.   };
  88.   /**
  89.    * Emits a `stop` event on the tracker task for the implementers to stop any
  90.    * child action being done, e.g. `requestAnimationFrame`.
  91.    * @return {object} Returns itself, so calls can be chained.
  92.    */
  93.   tracking.TrackerTask.prototype.stop = function() {
  94.     if (!this.inRunning()) {
  95.       return;
  96.     }
  98.     this.setRunning(false);
  99.     this.emit('stop');
  100.     this.tracker_.removeListener('track', this.reemitTrackEvent_);
  101.     return this;
  102.   };
  103. }());