1 /* 2 * Copyright (C) 2011 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 com.example.android.musicplayer; 18 19 import android.content.Context; 20 import android.media.AudioManager; 21 22 /** 23 * Convenience class to deal with audio focus. This class deals with everything related to audio 24 * focus: it can request and abandon focus, and will intercept focus change events and deliver 25 * them to a MusicFocusable interface (which, in our case, is implemented by {@link MusicService}). 26 * 27 * This class can only be used on SDK level 8 and above, since it uses API features that are not 28 * available on previous SDK's. 29 */ 30 public class AudioFocusHelper implements AudioManager.OnAudioFocusChangeListener { 31 AudioManager mAM; 32 MusicFocusable mFocusable; 33 AudioFocusHelper(Context ctx, MusicFocusable focusable)34 public AudioFocusHelper(Context ctx, MusicFocusable focusable) { 35 mAM = (AudioManager) ctx.getSystemService(Context.AUDIO_SERVICE); 36 mFocusable = focusable; 37 } 38 39 /** Requests audio focus. Returns whether request was successful or not. */ requestFocus()40 public boolean requestFocus() { 41 return AudioManager.AUDIOFOCUS_REQUEST_GRANTED == 42 mAM.requestAudioFocus(this, AudioManager.STREAM_MUSIC, AudioManager.AUDIOFOCUS_GAIN); 43 } 44 45 /** Abandons audio focus. Returns whether request was successful or not. */ abandonFocus()46 public boolean abandonFocus() { 47 return AudioManager.AUDIOFOCUS_REQUEST_GRANTED == mAM.abandonAudioFocus(this); 48 } 49 50 /** 51 * Called by AudioManager on audio focus changes. We implement this by calling our 52 * MusicFocusable appropriately to relay the message. 53 */ onAudioFocusChange(int focusChange)54 public void onAudioFocusChange(int focusChange) { 55 if (mFocusable == null) return; 56 switch (focusChange) { 57 case AudioManager.AUDIOFOCUS_GAIN: 58 mFocusable.onGainedAudioFocus(); 59 break; 60 case AudioManager.AUDIOFOCUS_LOSS: 61 case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT: 62 mFocusable.onLostAudioFocus(false); 63 break; 64 case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK: 65 mFocusable.onLostAudioFocus(true); 66 break; 67 default: 68 } 69 } 70 } 71