ui/file_manager/image_loader/piex_loader.js

   1 // Copyright 2015 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  * @typedef {{
   7  *   fulfill: function(PiexLoaderResponse):undefined,
   8  *   reject: function(string):undefined}
   9  * }}
  10  */
  11 var PiexRequestCallbacks;
  12
  13 /**
  14  * Color space.
  15  * @enum {string}
  16  */
  17 var ColorSpace = {
  18   SRGB: 'sRgb',
  19   ADOBE_RGB: 'adobeRgb'
  20 };
  21
  22 /**
  23  * @param {{id:number, thumbnail:!ArrayBuffer, orientation:number,
  24  *          colorSpace: ColorSpace}}
  25  *     data Data directly returned from NaCl module.
  26  * @constructor
  27  * @struct
  28  */
  29 function PiexLoaderResponse(data) {
  30   /**
  31    * @public {number}
  32    * @const
  33    */
  34   this.id = data.id;
  35
  36   /**
  37    * @public {!ArrayBuffer}
  38    * @const
  39    */
  40   this.thumbnail = data.thumbnail;
  41
  42   /**
  43    * @public {!ImageOrientation}
  44    * @const
  45    */
  46   this.orientation =
  47       ImageOrientation.fromExifOrientation(data.orientation);
  48
  49   /**
  50    * @public {ColorSpace}
  51    * @const
  52    */
  53   this.colorSpace = data.colorSpace;
  54 }
  55
  56 /**
  57  * @constructor
  58  * @struct
  59  */
  60 function PiexLoader() {
  61   /**
  62    * @private {!Element}
  63    * @const
  64    */
  65   this.naclModule_ = document.createElement('embed');
  66
  67   /**
  68    * @private {!Promise}
  69    * @const
  70    */
  71   this.naclPromise_ = new Promise(function(fulfill) {
  72     chrome.fileManagerPrivate.isPiexLoaderEnabled(fulfill);
  73   }).then(function(enabled) {
  74     if (!enabled)
  75       return Promise.reject('PiexLoader is not enabled for chromium build.');
  76     return new Promise(function(fulfill, reject) {
  77       var embed = this.naclModule_;
  78       embed.setAttribute('type', 'application/x-pnacl');
  79       // The extension nmf is not allowed to load. We uses .nmf.js instead.
  80       embed.setAttribute('src', '/piex/piex.nmf.txt');
  81       embed.width = 0;
  82       embed.height = 0;
  83
  84       // The <EMBED> element is wrapped inside a <DIV>, which has both a 'load'
  85       // and a 'message' event listener attached.  This wrapping method is used
  86       // instead of attaching the event listeners directly to the <EMBED>
  87       // element to ensure that the listeners are active before the NaCl module
  88       // 'load' event fires.
  89       var listenerContainer = document.createElement('div');
  90       listenerContainer.appendChild(embed);
  91       listenerContainer.addEventListener('load', fulfill, true);
  92       listenerContainer.addEventListener(
  93           'message', this.onMessage_.bind(this), true);
  94       listenerContainer.addEventListener('error', function() {
  95         reject(embed['lastError']);
  96       }.bind(this), true);
  97       listenerContainer.addEventListener('crash', function() {
  98         reject('PiexLoader crashed.');
  99       }.bind(this), true);
 100       listenerContainer.style.height = '0px';
 101       document.body.appendChild(listenerContainer);
 102     }.bind(this));
 103   }.bind(this));
 104
 105   /**
 106    * @private {!Object<number, PiexRequestCallbacks>}
 107    * @const
 108    */
 109   this.requests_ = {};
 110
 111   /**
 112    * @private {number}
 113    */
 114   this.requestIdCount_ = 0;
 115 }
 116
 117 /**
 118  * @param {Event} event
 119  * @private
 120  */
 121 PiexLoader.prototype.onMessage_ = function(event) {
 122   var id = event.data.id;
 123   if (!event.data.error) {
 124     var response = new PiexLoaderResponse(event.data);
 125     this.requests_[id].fulfill(response);
 126   } else {
 127     this.requests_[id].reject(event.data.error);
 128   }
 129   delete this.requests_[id];
 130 };
 131
 132 /**
 133  * Starts to load RAW image.
 134  * @param {string} url
 135  * @return {!Promise<!PiexLoaderResponse>}
 136  */
 137 PiexLoader.prototype.load = function(url) {
 138   return this.naclPromise_.then(function() {
 139     var message = {
 140       id: this.requestIdCount_++,
 141       name: 'loadThumbnail',
 142       url: url
 143     };
 144     this.naclModule_.postMessage(message);
 145     return new Promise(function(fulfill, reject) {
 146       this.requests_[message.id] = {fulfill: fulfill, reject: reject};
 147     }.bind(this));
 148   }.bind(this));
 149 };