Embeds offline voice recognizer plugin and its manager to app-list start page.

chrome/browser/resources/app_list/plugin_manager.js

+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/**
+ * @fileoverview The manager of offline hotword speech recognizer plugin.
+ */
+
+cr.define('speech', function() {
+  'use strict';
+
+  /**
+   * The type of the plugin state.
+   ** @enum {number}
+   */
+  var PluginState = {
+    UNINITIALIZED: 0,
+    LOADED: 1,
+    SAMPLING_RATE_READY: 2,
+    READY: 3,
+    RECOGNIZING: 4
+  };
+
+  /**
+   * The command names of the plugin.
+   * @enum {string}
+   */
+  var pluginCommands = {
+    SET_SAMPLING_RATE: 'h',
+    SET_CONFIG: 'm',
+    START_RECOGNIZING: 'r',
+    STOP_RECOGNIZING: 's'
+  };
+
+  /**
+   * The regexp pattern of the hotword recognition result.
+   */
+  var recognitionPattern = /^HotwordFiredEvent: \[(.*)\] confidence: (.*)/;
+
+  /**
+   * Checks the availability of the plugin.
+   * @return {boolean} True only if the plugin is available.
+   */
+  function isPluginAvailable() {
+    return !!($('recognizer') && $('recognizer').postMessage);
+  }
+
+  /**
+   * @constructor
+   */
+  function PluginManager(onReady, onRecognized) {
+    this.state = PluginState.UNINITIALIZED;
+    this.onReady_ = onReady;
+    this.onRecognized_ = onRecognized;
+    this.samplingRate_ = null;
+    this.config_ = null;
+    if (isPluginAvailable()) {
+      $('recognizer').addEventListener('message', this.onMessage_.bind(this));
+      $('recognizer').addEventListener('load', this.onLoad_.bind(this));
+    }
+  };
+
+  /**
+   * The event handler of the plugin status.
+   *
+   * @param {Event} messageEvent the event object from the plugin.
+   * @private
+   */
+  PluginManager.prototype.onMessage_ = function(messageEvent) {
+    if (this.state == PluginState.LOADED) {
+      if (messageEvent.data == 'stopped')
+        this.state = PluginState.SAMPLING_RATE_READY;
+      return;
+    }
+
+    if (messageEvent.data == 'audio') {
+      if (this.state < PluginState.READY)
+        this.onReady_();
+      this.state = PluginState.RECOGNIZING;
+    } else if (messageEvent.data == 'stopped') {
+      this.state = PluginState.READY;
+    } else {
+      var matched = recognitionPattern.exec(messageEvent.data);
+      if (matched && matched[1] == 'hotword_ok_google')
+        this.onRecognized_(Number(matched[2]));
+    }
+  };
+
+  /**
+   * The event handler when the plugin is loaded.
+   *
+   * @private
+   */
+  PluginManager.prototype.onLoad_ = function() {
+    if (this.state == PluginState.UNINITIALIZED) {
+      this.state = PluginState.LOADED;
+      if (this.samplingRate_ && this.config_)
+        this.initialize_(this.samplingRate_, this.config_);
+    }
+  };
+
+  /**
+   * Sends the initialization messages to the plugin. This method is private.
+   * The initialization will happen from onLoad_ or scheduleInitialize.
+   *
+   * @param {number} samplingRate the sampling rate the plugin accepts.
+   * @param {string} config the url of the config file.
+   * @private
+   */
+  PluginManager.prototype.initialize_ = function(samplingRate, config) {
+    $('recognizer').postMessage(
+        pluginCommands.SET_SAMPLING_RATE + samplingRate);
+    $('recognizer').postMessage(pluginCommands.SET_CONFIG + config);
+  };
+
+  /**
+   * Initializes the plugin with the specified parameter, or schedules the
+   * initialization if the plugin is not ready.
+   *
+   * @param {number} samplingRate the sampling rate the plugin accepts.
+   * @param {string} config the url of the config file.
+   */
+  PluginManager.prototype.scheduleInitialize = function(samplingRate, config) {
+    if (this.state == PluginState.UNINITIALIZED) {
+      this.samplingRate_ = samplingRate;
+      this.config_ = config;
+    } else {
+      this.initialize_(samplingRate, config);
+    }
+  };
+
+  /**
+   * Asks the plugin to start recognizing the hotword.
+   */
+  PluginManager.prototype.startRecognizer = function() {
+    $('recognizer').postMessage(pluginCommands.START_RECOGNIZING);
+  };
+
+  /**
+   * Asks the plugin to stop recognizing the hotword.
+   */
+  PluginManager.prototype.stopRecognizer = function() {
+    $('recognizer').postMessage(pluginCommands.STOP_RECOGNIZING);
+  };
+
+  /**
+   * Sends the actual audio wave data.
+   *
+   * @param {ArrayBuffer} data The audio data to be recognized.
+   */
+  PluginManager.prototype.sendAudioData = function(data) {
+    $('recognizer').postMessage(data);
+  };
+
+  return {
+    PluginManager: PluginManager,
+    PluginState: PluginState,
+    isPluginAvailable: isPluginAvailable
+  };
+});