chrome/common/extensions/docs/examples/api/power/background.js

   1 // Copyright (c) 2013 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  * States that the extension can be in.
   7  */
   8 var StateEnum = {
   9   DISABLED: 'disabled',
  10   DISPLAY: 'display',
  11   SYSTEM: 'system'
  12 };
  13
  14 /**
  15  * Key used for storing the current state in {localStorage}.
  16  */
  17 var STATE_KEY = 'state';
  18
  19 /**
  20  * Loads the locally-saved state asynchronously.
  21  * @param {function} callback Callback invoked with the loaded {StateEnum}.
  22  */
  23 function loadSavedState(callback) {
  24   chrome.storage.local.get(STATE_KEY, function(items) {
  25     var savedState = items[STATE_KEY];
  26     for (var key in StateEnum) {
  27       if (savedState == StateEnum[key]) {
  28         callback(savedState);
  29         return;
  30       }
  31     }
  32     callback(StateEnum.DISABLED);
  33   });
  34 }
  35
  36 /**
  37  * Switches to a new state.
  38  * @param {string} newState New {StateEnum} to use.
  39  */
  40 function setState(newState) {
  41   var imagePrefix = 'night';
  42   var title = '';
  43
  44   switch (newState) {
  45     case StateEnum.DISABLED:
  46       chrome.power.releaseKeepAwake();
  47       imagePrefix = 'night';
  48       title = chrome.i18n.getMessage('disabledTitle');
  49       break;
  50     case StateEnum.DISPLAY:
  51       chrome.power.requestKeepAwake('display');
  52       imagePrefix = 'day';
  53       title = chrome.i18n.getMessage('displayTitle');
  54       break;
  55     case StateEnum.SYSTEM:
  56       chrome.power.requestKeepAwake('system');
  57       imagePrefix = 'sunset';
  58       title = chrome.i18n.getMessage('systemTitle');
  59       break;
  60     default:
  61       throw 'Invalid state "' + newState + '"';
  62   }
  63
  64   var items = {};
  65   items[STATE_KEY] = newState;
  66   chrome.storage.local.set(items);
  67
  68   chrome.browserAction.setIcon({
  69     path: {
  70       '19': 'images/' + imagePrefix + '-19.png',
  71       '38': 'images/' + imagePrefix + '-38.png'
  72     }
  73   });
  74   chrome.browserAction.setTitle({title: title});
  75 }
  76
  77 chrome.browserAction.onClicked.addListener(function() {
  78   loadSavedState(function(state) {
  79     switch (state) {
  80       case StateEnum.DISABLED:
  81         setState(StateEnum.DISPLAY);
  82         break;
  83       case StateEnum.DISPLAY:
  84         setState(StateEnum.SYSTEM);
  85         break;
  86       case StateEnum.SYSTEM:
  87         setState(StateEnum.DISABLED);
  88         break;
  89       default:
  90         throw 'Invalid state "' + state + '"';
  91     }
  92   });
  93 });
  94
  95 chrome.runtime.onStartup.addListener(function() {
  96   loadSavedState(function(state) { setState(state); });
  97 });
  98
  99 chrome.runtime.onInstalled.addListener(function(details) {
 100   loadSavedState(function(state) { setState(state); });
 101 });