content: /*
   * Copyright (C) 2008 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package android.speech;
  
  import java.util.ArrayList;
  
  import android.app.Activity;
  import android.content.ActivityNotFoundException;
  import android.content.BroadcastReceiver;
  import android.content.ComponentName;
  import android.content.Context;
  import android.content.Intent;
  import android.content.pm.PackageManager;
  import android.content.pm.ResolveInfo;
  import android.os.Bundle;
  
  /**
   * Constants for supporting speech recognition through starting an {@link Intent}
   */
  public class RecognizerIntent {
      /**
       * The extra key used in an intent to the speech recognizer for voice search. Not
       * generally to be used by developers. The system search dialog uses this, for example,
       * to set a calling package for identification by a voice search API. If this extra
       * is set by anyone but the system process, it should be overridden by the voice search
       * implementation.
       */
      public final static String EXTRA_CALLING_PACKAGE = "calling_package";
  
      private RecognizerIntent() {
          // Not for instantiating.
      }
  
      /**
       * Starts an activity that will prompt the user for speech and send it through a
       * speech recognizer.  The results will be returned via activity results (in
       * {@link Activity#onActivityResult}, if you start the intent using
       * {@link Activity#startActivityForResult(Intent, int)}), or forwarded via a PendingIntent
       * if one is provided.
       * 
       * <p>Starting this intent with just {@link Activity#startActivity(Intent)} is not supported.
       * You must either use {@link Activity#startActivityForResult(Intent, int)}, or provide a
       * PendingIntent, to receive recognition results.
       *
       * <p>The implementation of this API is likely to stream audio to remote servers to perform
       * speech recognition which can use a substantial amount of bandwidth.
       *
       * <p>Required extras:
       * <ul>
       *   <li>{@link #EXTRA_LANGUAGE_MODEL}
       * </ul>
       * 
       * <p>Optional extras:
       * <ul>
       *   <li>{@link #EXTRA_PROMPT}
       *   <li>{@link #EXTRA_LANGUAGE}
       *   <li>{@link #EXTRA_MAX_RESULTS}
       *   <li>{@link #EXTRA_RESULTS_PENDINGINTENT}
       *   <li>{@link #EXTRA_RESULTS_PENDINGINTENT_BUNDLE}
       * </ul>
       * 
       * <p> Result extras (returned in the result, not to be specified in the request):
       * <ul>
       *   <li>{@link #EXTRA_RESULTS}
       * </ul>
       * 
       * <p>NOTE: There may not be any applications installed to handle this action, so you should
       * make sure to catch {@link ActivityNotFoundException}.
       */
      public static final String ACTION_RECOGNIZE_SPEECH = "android.speech.action.RECOGNIZE_SPEECH";
  
      /**
       * Starts an activity that will prompt the user for speech, send it through a
       * speech recognizer, and either display a web search result or trigger
       * another type of action based on the user's speech.
       *
       * <p>If you want to avoid triggering any type of action besides web search, you can use
       * the {@link #EXTRA_WEB_SEARCH_ONLY} extra.
       * 
       * <p>Required extras:
       * <ul>
       *   <li>{@link #EXTRA_LANGUAGE_MODEL}
       * </ul>
       * 
       * <p>Optional extras:
       * <ul>
       *   <li>{@link #EXTRA_PROMPT}
       *   <li>{@link #EXTRA_LANGUAGE}
       *   <li>{@link #EXTRA_MAX_RESULTS}
       *   <li>{@link #EXTRA_PARTIAL_RESULTS}
       *   <li>{@link #EXTRA_WEB_SEARCH_ONLY}
       *   <li>{@link #EXTRA_ORIGIN}
       * </ul>
       * 
       * <p> Result extras (returned in the result, not to be specified in the request):
       * <ul>
       *   <li>{@link #EXTRA_RESULTS}
       *   <li>{@link #EXTRA_CONFIDENCE_SCORES} (optional)
       * </ul>
       * 
       * <p>NOTE: There may not be any applications installed to handle this action, so you should
       * make sure to catch {@link ActivityNotFoundException}.
       */
      public static final String ACTION_WEB_SEARCH = "android.speech.action.WEB_SEARCH";
  
      /**
       * Starts an activity that will prompt the user for speech without requiring the user's
       * visual attention or touch input. It will send it through a speech recognizer,
       * and either synthesize speech for a web search result or trigger
       * another type of action based on the user's speech.
       *
       * This activity may be launched while device is locked in a secure mode.
       * Special care must be taken to ensure that the voice actions that are performed while
       * hands free cannot compromise the device's security.
       * The activity should check the value of the {@link #EXTRA_SECURE} extra to determine
       * whether the device has been securely locked. If so, the activity should either restrict
       * the set of voice actions that are permitted or require some form of secure
       * authentication before proceeding.
       *
       * To ensure that the activity's user interface is visible while the lock screen is showing,
       * the activity should set the
       * {@link android.view.WindowManager.LayoutParams#FLAG_SHOW_WHEN_LOCKED} window flag.
       * Otherwise the activity's user interface may be hidden by the lock screen. The activity
       * should take care not to leak private information when the device is securely locked.
       *
       * <p>Optional extras:
       * <ul>
       *   <li>{@link #EXTRA_SECURE}
       * </ul>
       *
       * <p class="note">
       * In some cases, a matching Activity may not exist, so ensure you
       * safeguard against this.
       */
      public static final String ACTION_VOICE_SEARCH_HANDS_FREE =
              "android.speech.action.VOICE_SEARCH_HANDS_FREE";
  
      /**
       * Optional boolean to indicate that a "hands free" voice search was performed while the device
       * was in a secure mode. An example of secure mode is when the device's screen lock is active,
       * and it requires some form of authentication to be unlocked.
       *
       * When the device is securely locked, the voice search activity should either restrict
       * the set of voice actions that are permitted, or require some form of secure authentication
       * before proceeding.
       */
      public static final String EXTRA_SECURE = "android.speech.extras.EXTRA_SECURE";
  
      /**
       * The minimum length of an utterance. We will not stop recording before this amount of time.
       * 
       * Note that it is extremely rare you'd want to specify this value in an intent. If you don't
       * have a very good reason to change these, you should leave them as they are. Note also that
       * certain values may cause undesired or unexpected results - use judiciously! Additionally,
       * depending on the recognizer implementation, these values may have no effect.
       */
      public static final String EXTRA_SPEECH_INPUT_MINIMUM_LENGTH_MILLIS =
              "android.speech.extras.SPEECH_INPUT_MINIMUM_LENGTH_MILLIS";
  
      /**
       * The amount of time that it should take after we stop hearing speech to consider the input
       * complete. 
       * 
       * Note that it is extremely rare you'd want to specify this value in an intent. If
       * you don't have a very good reason to change these, you should leave them as they are. Note
       * also that certain values may cause undesired or unexpected results - use judiciously!
       * Additionally, depending on the recognizer implementation, these values may have no effect.
       */
      public static final String EXTRA_SPEECH_INPUT_COMPLETE_SILENCE_LENGTH_MILLIS =
              "android.speech.extras.SPEECH_INPUT_COMPLETE_SILENCE_LENGTH_MILLIS";
  
      /**
       * The amount of time that it should take after we stop hearing speech to consider the input
       * possibly complete. This is used to prevent the endpointer cutting off during very short
       * mid-speech pauses. 
       * 
       * Note that it is extremely rare you'd want to specify this value in an intent. If
       * you don't have a very good reason to change these, you should leave them as they are. Note
       * also that certain values may cause undesired or unexpected results - use judiciously!
       * Additionally, depending on the recognizer implementation, these values may have no effect.
       */
      public static final String EXTRA_SPEECH_INPUT_POSSIBLY_COMPLETE_SILENCE_LENGTH_MILLIS =
              "android.speech.extras.SPEECH_INPUT_POSSIBLY_COMPLETE_SILENCE_LENGTH_MILLIS";
  
      /**
       * Informs the recognizer which speech model to prefer when performing
       * {@link #ACTION_RECOGNIZE_SPEECH}. The recognizer uses this
       * information to fine tune the results. This extra is required. Activities implementing
       * {@link #ACTION_RECOGNIZE_SPEECH} may interpret the values as they see fit.
       * 
       *  @see #LANGUAGE_MODEL_FREE_FORM
       *  @see #LANGUAGE_MODEL_WEB_SEARCH
       */
      public static final String EXTRA_LANGUAGE_MODEL = "android.speech.extra.LANGUAGE_MODEL";
  
      /** 
       * Use a language model based on free-form speech recognition.  This is a value to use for 
       * {@link #EXTRA_LANGUAGE_MODEL}. 
       * @see #EXTRA_LANGUAGE_MODEL
       */
      public static final String LANGUAGE_MODEL_FREE_FORM = "free_form";
      /** 
       * Use a language model based on web search terms.  This is a value to use for 
       * {@link #EXTRA_LANGUAGE_MODEL}. 
       * @see #EXTRA_LANGUAGE_MODEL
       */
      public static final String LANGUAGE_MODEL_WEB_SEARCH = "web_search";
  
      /** Optional text prompt to show to the user when asking them to speak. */
      public static final String EXTRA_PROMPT = "android.speech.extra.PROMPT";
  
      /**
       * Optional IETF language tag (as defined by BCP 47), for example "en-US". This tag informs the
       * recognizer to perform speech recognition in a language different than the one set in the
       * {@link java.util.Locale#getDefault()}.
       */
      public static final String EXTRA_LANGUAGE = "android.speech.extra.LANGUAGE";
      
      /**
       * Optional value which can be used to indicate the referer url of a page in which
       * speech was requested. For example, a web browser may choose to provide this for
       * uses of speech on a given page.
       */
      public static final String EXTRA_ORIGIN = "android.speech.extra.ORIGIN";
  
      /** 
       * Optional limit on the maximum number of results to return. If omitted the recognizer
       * will choose how many results to return. Must be an integer.
       */
      public static final String EXTRA_MAX_RESULTS = "android.speech.extra.MAX_RESULTS";
      
      /**
       * Optional boolean, to be used with {@link #ACTION_WEB_SEARCH}, to indicate whether to
       * only fire web searches in response to a user's speech. The default is false, meaning
       * that other types of actions can be taken based on the user's speech.
       */
      public static final String EXTRA_WEB_SEARCH_ONLY = "android.speech.extra.WEB_SEARCH_ONLY";
  
      /**
       * Optional boolean to indicate whether partial results should be returned by the recognizer
       * as the user speaks (default is false).  The server may ignore a request for partial
       * results in some or all cases.
       */
      public static final String EXTRA_PARTIAL_RESULTS = "android.speech.extra.PARTIAL_RESULTS";
  
      /**
       * When the intent is {@link #ACTION_RECOGNIZE_SPEECH}, the speech input activity will
       * return results to you via the activity results mechanism.  Alternatively, if you use this
       * extra to supply a PendingIntent, the results will be added to its bundle and the 
       * PendingIntent will be sent to its target.
       */
      public static final String EXTRA_RESULTS_PENDINGINTENT = 
              "android.speech.extra.RESULTS_PENDINGINTENT";
      
      /**
       * If you use {@link #EXTRA_RESULTS_PENDINGINTENT} to supply a forwarding intent, you can
       * also use this extra to supply additional extras for the final intent.  The search results
       * will be added to this bundle, and the combined bundle will be sent to the target.
       */
      public static final String EXTRA_RESULTS_PENDINGINTENT_BUNDLE = 
              "android.speech.extra.RESULTS_PENDINGINTENT_BUNDLE";
  
      /** Result code returned when no matches are found for the given speech */
      public static final int RESULT_NO_MATCH = Activity.RESULT_FIRST_USER;
      /** Result code returned when there is a generic client error */
      public static final int RESULT_CLIENT_ERROR = Activity.RESULT_FIRST_USER + 1;
      /** Result code returned when the recognition server returns an error */
      public static final int RESULT_SERVER_ERROR = Activity.RESULT_FIRST_USER + 2;
      /** Result code returned when a network error was encountered */
      public static final int RESULT_NETWORK_ERROR = Activity.RESULT_FIRST_USER + 3;
      /** Result code returned when an audio error was encountered */
      public static final int RESULT_AUDIO_ERROR = Activity.RESULT_FIRST_USER + 4;
  
      /**
       * An ArrayList&lt;String&gt; of the recognition results when performing
       * {@link #ACTION_RECOGNIZE_SPEECH}. Generally this list should be ordered in
       * descending order of speech recognizer confidence. (See {@link #EXTRA_CONFIDENCE_SCORES}).
       * Returned in the results; not to be specified in the recognition request. Only present
       * when {@link Activity#RESULT_OK} is returned in an activity result. In a PendingIntent,
       * the lack of this extra indicates failure.
       */
      public static final String EXTRA_RESULTS = "android.speech.extra.RESULTS";
      
      /**
       * A float array of confidence scores of the recognition results when performing
       * {@link #ACTION_RECOGNIZE_SPEECH}. The array should be the same size as the ArrayList
       * returned in {@link #EXTRA_RESULTS}, and should contain values ranging from 0.0 to 1.0,
       * or -1 to represent an unavailable confidence score.
       * <p>
       * Confidence values close to 1.0 indicate high confidence (the speech recognizer is
       * confident that the recognition result is correct), while values close to 0.0 indicate
       * low confidence.
       * <p>
       * Returned in the results; not to be specified in the recognition request. This extra is
       * optional and might not be provided. Only present when {@link Activity#RESULT_OK} is
       * returned in an activity result.
       */
      public static final String EXTRA_CONFIDENCE_SCORES = "android.speech.extra.CONFIDENCE_SCORES";
      
      /**
       * Returns the broadcast intent to fire with
       * {@link Context#sendOrderedBroadcast(Intent, String, BroadcastReceiver, android.os.Handler, int, String, Bundle)}
       * to receive details from the package that implements voice search.
       * <p>
       * This is based on the value specified by the voice search {@link Activity} in
       * {@link #DETAILS_META_DATA}, and if this is not specified, will return null. Also if there
       * is no chosen default to resolve for {@link #ACTION_WEB_SEARCH}, this will return null.
       * <p>
       * If an intent is returned and is fired, a {@link Bundle} of extras will be returned to the
       * provided result receiver, and should ideally contain values for
       * {@link #EXTRA_LANGUAGE_PREFERENCE} and {@link #EXTRA_SUPPORTED_LANGUAGES}.
       * <p>
       * (Whether these are actually provided is up to the particular implementation. It is
       * recommended that {@link Activity}s implementing {@link #ACTION_WEB_SEARCH} provide this
       * information, but it is not required.)
       * 
       * @param context a context object
       * @return the broadcast intent to fire or null if not available
       */
      public static final Intent getVoiceDetailsIntent(Context context) {
          Intent voiceSearchIntent = new Intent(ACTION_WEB_SEARCH);
          ResolveInfo ri = context.getPackageManager().resolveActivity(
                  voiceSearchIntent, PackageManager.GET_META_DATA);
          if (ri == null || ri.activityInfo == null || ri.activityInfo.metaData == null) return null;
          
          String className = ri.activityInfo.metaData.getString(DETAILS_META_DATA);
          if (className == null) return null;
          
          Intent detailsIntent = new Intent(ACTION_GET_LANGUAGE_DETAILS);
          detailsIntent.setComponent(new ComponentName(ri.activityInfo.packageName, className));
          return detailsIntent;
      }
      
      /**
       * Meta-data name under which an {@link Activity} implementing {@link #ACTION_WEB_SEARCH} can
       * use to expose the class name of a {@link BroadcastReceiver} which can respond to request for
       * more information, from any of the broadcast intents specified in this class.
       * <p>
       * Broadcast intents can be directed to the class name specified in the meta-data by creating
       * an {@link Intent}, setting the component with
       * {@link Intent#setComponent(android.content.ComponentName)}, and using
       * {@link Context#sendOrderedBroadcast(Intent, String, BroadcastReceiver, android.os.Handler, int, String, android.os.Bundle)}
       * with another {@link BroadcastReceiver} which can receive the results.
       * <p>
       * The {@link #getVoiceDetailsIntent(Context)} method is provided as a convenience to create
       * a broadcast intent based on the value of this meta-data, if available.
       * <p>
       * This is optional and not all {@link Activity}s which implement {@link #ACTION_WEB_SEARCH}
       * are required to implement this. Thus retrieving this meta-data may be null.
       */
      public static final String DETAILS_META_DATA = "android.speech.DETAILS";
      
      /**
       * A broadcast intent which can be fired to the {@link BroadcastReceiver} component specified
       * in the meta-data defined in the {@link #DETAILS_META_DATA} meta-data of an
       * {@link Activity} satisfying {@link #ACTION_WEB_SEARCH}.
       * <p>
       * When fired with
       * {@link Context#sendOrderedBroadcast(Intent, String, BroadcastReceiver, android.os.Handler, int, String, android.os.Bundle)},
       * a {@link Bundle} of extras will be returned to the provided result receiver, and should
       * ideally contain values for {@link #EXTRA_LANGUAGE_PREFERENCE} and
       * {@link #EXTRA_SUPPORTED_LANGUAGES}.
       * <p>
       * (Whether these are actually provided is up to the particular implementation. It is
       * recommended that {@link Activity}s implementing {@link #ACTION_WEB_SEARCH} provide this
       * information, but it is not required.)
       */
      public static final String ACTION_GET_LANGUAGE_DETAILS =
              "android.speech.action.GET_LANGUAGE_DETAILS";
      
      /**
       * Specify this boolean extra in a broadcast of {@link #ACTION_GET_LANGUAGE_DETAILS} to
       * indicate that only the current language preference is needed in the response. This
       * avoids any additional computation if all you need is {@link #EXTRA_LANGUAGE_PREFERENCE}
       * in the response.
       */
      public static final String EXTRA_ONLY_RETURN_LANGUAGE_PREFERENCE =
              "android.speech.extra.ONLY_RETURN_LANGUAGE_PREFERENCE";
      
      /**
       * The key to the extra in the {@link Bundle} returned by {@link #ACTION_GET_LANGUAGE_DETAILS}
       * which is a {@link String} that represents the current language preference this user has
       * specified - a locale string like "en-US".
       */
      public static final String EXTRA_LANGUAGE_PREFERENCE =
              "android.speech.extra.LANGUAGE_PREFERENCE";
      
      /**
       * The key to the extra in the {@link Bundle} returned by {@link #ACTION_GET_LANGUAGE_DETAILS}
       * which is an {@link ArrayList} of {@link String}s that represents the languages supported by
       * this implementation of voice recognition - a list of strings like "en-US", "cmn-Hans-CN",
       * etc.
       */
      public static final String EXTRA_SUPPORTED_LANGUAGES =
              "android.speech.extra.SUPPORTED_LANGUAGES";
  
      /**
       * Optional boolean, to be used with {@link #ACTION_RECOGNIZE_SPEECH},
       * {@link #ACTION_VOICE_SEARCH_HANDS_FREE}, {@link #ACTION_WEB_SEARCH} to indicate whether to
       * only use an offline speech recognition engine. The default is false, meaning that either
       * network or offline recognition engines may be used.
       */
      public static final String EXTRA_PREFER_OFFLINE = "android.speech.extra.PREFER_OFFLINE";
  }
  