native_client_sdk/src/gonacl_appengine/static/earth/example.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 'use strict';
   6
   7 var naclModule = null;
   8
   9 /**
  10  * A helper function to abbreviate getElementById.
  11  *
  12  * @param {string} elementId The id to get.
  13  * @return {Element}
  14  */
  15 function $(elementId) {
  16   return document.getElementById(elementId);
  17 }
  18
  19 /**
  20  * MIME type for PNaCl
  21  *
  22  * @return {string} MIME type
  23  */
  24 function PNaClmimeType() {
  25   return 'application/x-pnacl';
  26 }
  27
  28 /**
  29  * Check if the browser supports PNaCl.
  30  *
  31  * @return {bool}
  32  */
  33 function browserSupportsPNaCl() {
  34   var mimetype = PNaClmimeType();
  35   return navigator.mimeTypes[mimetype] !== undefined;
  36 }
  37
  38 /**
  39  * Get the URL for Google Cloud Storage.
  40  *
  41  * @param {string} name The relative path to the file.
  42  * @return {string}
  43  */
  44 function getDataURL(name) {
  45   var revision = '236779';
  46   var baseUrl = '//storage.googleapis.com/gonacl/demos/publish/';
  47   return baseUrl + revision + '/earth/' + name;
  48 }
  49
  50 /**
  51  * Create the Native Client <embed> element as a child of the DOM element
  52  * named "listener".
  53  *
  54  * @param {string} name The name of the example.
  55  * @param {number} width The width to create the plugin.
  56  * @param {number} height The height to create the plugin.
  57  * @param {Object} attrs Dictionary of attributes to set on the module.
  58  */
  59 function createNaClModule(name, width, height, attrs) {
  60   var moduleEl = document.createElement('embed');
  61   moduleEl.setAttribute('name', 'nacl_module');
  62   moduleEl.setAttribute('id', 'nacl_module');
  63   moduleEl.setAttribute('width', width);
  64   moduleEl.setAttribute('height', height);
  65   moduleEl.setAttribute('path', '');
  66   moduleEl.setAttribute('src', getDataURL(name + '.nmf'));
  67   moduleEl.setAttribute('type', PNaClmimeType());
  68
  69   // Add any optional arguments
  70   if (attrs) {
  71     for (var key in attrs) {
  72       moduleEl.setAttribute(key, attrs[key]);
  73     }
  74   }
  75
  76   // The <EMBED> element is wrapped inside a <DIV>, which has both a 'load'
  77   // and a 'message' event listener attached.  This wrapping method is used
  78   // instead of attaching the event listeners directly to the <EMBED> element
  79   // to ensure that the listeners are active before the NaCl module 'load'
  80   // event fires.
  81   var listenerDiv = $('listener');
  82   listenerDiv.appendChild(moduleEl);
  83 }
  84
  85 /**
  86  * Add the default event listeners to the element with id "listener".
  87  */
  88 function attachDefaultListeners() {
  89   var listenerDiv = $('listener');
  90   listenerDiv.addEventListener('load', moduleDidLoad, true);
  91   listenerDiv.addEventListener('error', moduleLoadError, true);
  92   listenerDiv.addEventListener('progress', moduleLoadProgress, true);
  93   listenerDiv.addEventListener('message', handleMessage, true);
  94   listenerDiv.addEventListener('crash', handleCrash, true);
  95   attachListeners();
  96 }
  97
  98 /**
  99  * Called when the Browser can not communicate with the Module
 100  *
 101  * This event listener is registered in attachDefaultListeners above.
 102  *
 103  * @param {Object} event
 104  */
 105 function handleCrash(event) {
 106   if (naclModule.exitStatus == -1) {
 107     updateStatus('CRASHED');
 108   } else {
 109     updateStatus('EXITED [' + naclModule.exitStatus + ']');
 110   }
 111 }
 112
 113 /**
 114  * Called when the NaCl module is loaded.
 115  *
 116  * This event listener is registered in attachDefaultListeners above.
 117  */
 118 function moduleDidLoad() {
 119   var bar = $('progress-bar');
 120   bar.style.width = 100;
 121   naclModule = $('nacl_module');
 122   hideStatus();
 123   setThreadCount();
 124 }
 125
 126 /**
 127  * Hide the status field and progress bar.
 128  */
 129 function hideStatus() {
 130   $('loading-cover').style.display = 'none';
 131 }
 132
 133 /**
 134  * Called when the plugin fails to load.
 135  *
 136  * @param {Object} event
 137  */
 138 function moduleLoadError(event) {
 139   updateStatus('Load failed.');
 140 }
 141
 142 /**
 143  * Called when the plugin reports progress events.
 144  *
 145  * @param {Object} event
 146  */
 147 function moduleLoadProgress(event) {
 148   $('progress').style.display = 'block';
 149
 150   var loadPercent = 0.0;
 151   var bar = $('progress-bar');
 152
 153   if (event.lengthComputable && event.total > 0) {
 154     loadPercent = event.loaded / event.total * 100.0;
 155   } else {
 156     // The total length is not yet known.
 157     loadPercent = 10;
 158   }
 159   bar.style.width = loadPercent + "%";
 160 }
 161
 162
 163 /**
 164  * If the element with id 'statusField' exists, then set its HTML to the status
 165  * message as well.
 166  *
 167  * @param {string} opt_message The message to set.
 168  */
 169 function updateStatus(opt_message) {
 170   var statusField = $('statusField');
 171   if (statusField) {
 172     statusField.style.display = 'block';
 173     statusField.textContent = opt_message;
 174   }
 175 }
 176
 177 /**
 178  * Send the current value of the element threadCount to the NaCl module.
 179  *
 180  * @param {number} threads The number of threads to use to render.
 181  */
 182 function setThreadCount(threads) {
 183   var value = parseInt($('threadCount').value);
 184   naclModule.postMessage({'message': 'set_threads',
 185                           'value': value});
 186 }
 187
 188 /**
 189  * Add event listeners after the NaCl module has loaded.  These listeners will
 190  * forward messages to the NaCl module via postMessage()
 191  */
 192 function attachListeners() {
 193   $('threadCount').addEventListener('change', setThreadCount);
 194   $('zoomRange').addEventListener('change',
 195     function() {
 196       var value = parseFloat($('zoomRange').value);
 197       naclModule.postMessage({'message' : 'set_zoom',
 198                               'value' : value});
 199     });
 200   $('lightRange').addEventListener('change',
 201     function() {
 202       var value = parseFloat($('lightRange').value);
 203       naclModule.postMessage({'message' : 'set_light',
 204                               'value' : value});
 205     });
 206 }
 207
 208 /**
 209  * Load a texture and send pixel data down to NaCl module.
 210  * @param {string} name
 211  */
 212 function loadTexture(name) {
 213   // Load image from jpg, decompress into canvas.
 214   var img = new Image();
 215   img.onload = function() {
 216     var graph = document.createElement('canvas');
 217     graph.width = img.width;
 218     graph.height = img.height;
 219     var context = graph.getContext('2d');
 220     context.drawImage(img, 0, 0);
 221     var imageData = context.getImageData(0, 0, img.width, img.height);
 222     // Send NaCl module the raw image data obtained from canvas.
 223     naclModule.postMessage({'message' : 'texture',
 224                             'name' : name,
 225                             'width' : img.width,
 226                             'height' : img.height,
 227                             'data' : imageData.data.buffer});
 228   };
 229   // A cross-origin request to an image is "tainted", and cannot be read into a
 230   // canvas without specifying this. See
 231   // https://developer.mozilla.org/en-US/docs/HTML/CORS_Enabled_Image
 232   img.crossOrigin = 'Anonymous';
 233   img.src = getDataURL(name);
 234 }
 235
 236 /**
 237  * Handle a message coming from the NaCl module.
 238  * @param {Object} message_event
 239  */
 240 function handleMessage(message_event) {
 241   var message = message_event.data.message;
 242   var value = message_event.data.value;
 243   if (message == 'set_zoom') {
 244     // zoom slider
 245     $('zoomRange').value = value;
 246   } else if (message == 'set_light') {
 247     // light slider
 248     $('lightRange').value = value;
 249   } else if (message == 'request_textures') {
 250     // NaCl module is requesting a set of textures.
 251     var names = message_event.data.names;
 252     for (var i = 0; i < names.length; i++)
 253       loadTexture(names[i]);
 254   } else if (message == 'fps') {
 255     // NaCl module notifying current FPS.
 256     $('fps').textContent = message_event.data.value.toFixed(1);
 257   }
 258 }
 259
 260 /**
 261  * Listen for the DOM content to be loaded. This event is fired when parsing of
 262  * the page's document has finished.
 263  */
 264 document.addEventListener('DOMContentLoaded', function() {
 265   updateStatus('Loading...');
 266   if (!browserSupportsPNaCl()) {
 267     updateStatus('Browser does not support PNaCl or PNaCl is disabled');
 268   } else if (naclModule == null) {
 269     createNaClModule('earth', '100%', '100%');
 270     attachDefaultListeners();
 271   } else {
 272     // It's possible that the Native Client module onload event fired
 273     // before the page's onload event.  In this case, the status message
 274     // will reflect 'SUCCESS', but won't be displayed.  This call will
 275     // display the current message.
 276     updateStatus('Waiting.');
 277   }
 278 });