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      1 /*
      2  * Copyright (C) 2012 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.media;
     18 
     19 /**
     20  * The MediaSyncEvent class defines events that can be used to synchronize playback or capture
     21  * actions between different players and recorders.
     22  * <p>For instance, {@link AudioRecord#startRecording(MediaSyncEvent)} is used to start capture
     23  * only when the playback on a particular audio session is complete.
     24  * The audio session ID is retrieved from a player (e.g {@link MediaPlayer}, {@link AudioTrack} or
     25  * {@link ToneGenerator}) by use of the getAudioSessionId() method.
     26  */
     27 public class MediaSyncEvent {
     28 
     29     /**
     30      * No sync event specified. When used with a synchronized playback or capture method, the
     31      * behavior is equivalent to calling the corresponding non synchronized method.
     32      */
     33     public static final int SYNC_EVENT_NONE = AudioSystem.SYNC_EVENT_NONE;
     34 
     35     /**
     36      * The corresponding action is triggered only when the presentation is completed
     37      * (meaning the media has been presented to the user) on the specified session.
     38      * A synchronization of this type requires a source audio session ID to be set via
     39      * {@link #setAudioSessionId(int)} method.
     40      */
     41     public static final int SYNC_EVENT_PRESENTATION_COMPLETE =
     42                                                     AudioSystem.SYNC_EVENT_PRESENTATION_COMPLETE;
     43 
     44 
     45     /**
     46      * Creates a synchronization event of the sepcified type.
     47      *
     48      * <p>The type specifies which kind of event is monitored.
     49      * For instance, event {@link #SYNC_EVENT_PRESENTATION_COMPLETE} corresponds to the audio being
     50      * presented to the user on a particular audio session.
     51      * @param eventType the synchronization event type.
     52      * @return the MediaSyncEvent created.
     53      * @throws java.lang.IllegalArgumentException
     54      */
     55     public static MediaSyncEvent createEvent(int eventType)
     56                             throws IllegalArgumentException {
     57         if (!isValidType(eventType)) {
     58             throw (new IllegalArgumentException(eventType
     59                     + "is not a valid MediaSyncEvent type."));
     60         } else {
     61             return new MediaSyncEvent(eventType);
     62         }
     63     }
     64 
     65     private final int mType;
     66     private int mAudioSession = 0;
     67 
     68     private MediaSyncEvent(int eventType) {
     69         mType = eventType;
     70     }
     71 
     72     /**
     73      * Sets the event source audio session ID.
     74      *
     75      * <p>The audio session ID specifies on which audio session the synchronization event should be
     76      * monitored.
     77      * It is mandatory for certain event types (e.g. {@link #SYNC_EVENT_PRESENTATION_COMPLETE}).
     78      * For instance, the audio session ID can be retrieved via
     79      * {@link MediaPlayer#getAudioSessionId()} when monitoring an event on a particular MediaPlayer.
     80      * @param audioSessionId the audio session ID of the event source being monitored.
     81      * @return the MediaSyncEvent the method is called on.
     82      * @throws java.lang.IllegalArgumentException
     83      */
     84     public MediaSyncEvent setAudioSessionId(int audioSessionId)
     85             throws IllegalArgumentException {
     86         if (audioSessionId > 0) {
     87             mAudioSession = audioSessionId;
     88         } else {
     89             throw (new IllegalArgumentException(audioSessionId + " is not a valid session ID."));
     90         }
     91         return this;
     92     }
     93 
     94     /**
     95      * Gets the synchronization event type.
     96      *
     97      * @return the synchronization event type.
     98      */
     99     public int getType() {
    100         return mType;
    101     }
    102 
    103     /**
    104      * Gets the synchronization event audio session ID.
    105      *
    106      * @return the synchronization audio session ID. The returned audio session ID is 0 if it has
    107      * not been set.
    108      */
    109     public int getAudioSessionId() {
    110         return mAudioSession;
    111     }
    112 
    113     private static boolean isValidType(int type) {
    114         switch (type) {
    115         case SYNC_EVENT_NONE:
    116         case SYNC_EVENT_PRESENTATION_COMPLETE:
    117             return true;
    118         default:
    119             return false;
    120         }
    121     }
    122 }
    123