ui/file_manager/audio_player/js/audio_player_model.js

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 /**
   6  * The model class for audio player.
   7  * @constructor
   8  */
   9 function AudioPlayerModel() {}
  10
  11 AudioPlayerModel.prototype.initialize = function(callback) {
  12   'use strict';
  13
  14   /**
  15    * List of values to be stored into the model.
  16    * @type {!Object<*>}
  17    * @const
  18    */
  19   var VALUES =
  20     /**
  21      * They will be used as properties of AudioPlayerModel.
  22      * @lends {AudioPlayerModel.prototype}
  23      */
  24     {
  25       shuffle: false,
  26       repeat: false,
  27       volume: 100,
  28       expanded: false,
  29     };
  30
  31   /**
  32    * Prefix of the stored values in the storage.
  33    * @type {string}
  34    */
  35   var STORAGE_PREFIX = 'audioplayer-';
  36
  37   /**
  38    * Save the values in the model into the storage.
  39    * @param {AudioPlayerModel} model The model.
  40    */
  41   function saveModel(model) {
  42     var objectToBeSaved = {};
  43     for (var key in VALUES) {
  44       objectToBeSaved[STORAGE_PREFIX + key] = model[key];
  45     }
  46
  47     chrome.storage.local.set(objectToBeSaved);
  48   };
  49
  50   /**
  51    * Load the values in the model from the storage.
  52    * @param {AudioPlayerModel} model The model.
  53    * @param {function()} inCallback Called when the load is completed.
  54    */
  55   function loadModel(model, inCallback) {
  56     // Restores the values from the storage
  57     var objectsToBeRead = Object.keys(VALUES).
  58                           map(function(a) {
  59                             return STORAGE_PREFIX + a;
  60                           });
  61
  62     chrome.storage.local.get(objectsToBeRead, function(result) {
  63       for (var key in result) {
  64         // Strips the prefix.
  65         model[key.substr(STORAGE_PREFIX.length)] = result[key];
  66       }
  67       inCallback();
  68     });
  69   };
  70
  71   // Initializes values.
  72   for (var key in VALUES) {
  73     this[key] = VALUES[key];
  74   }
  75   Object.seal(this);
  76
  77   // Restores the values from the storage
  78   var target = this;
  79   loadModel(target, function() {
  80     // Installs observer to watch changes of the values.
  81     Object.observe(target, function(changes) {
  82       saveModel(target);
  83     });
  84     callback();
  85   });
  86 }