AudioFocusRequest: more docs, listener without handler (97de334f) · Commits · e / os / android_frameworks_base

api/current.txt

+1 −0

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		@@ -21006,6 +21006,7 @@ package android.media {
		method public android.media.AudioFocusRequest.Builder setAcceptsDelayedFocusGain(boolean);
		method public android.media.AudioFocusRequest.Builder setAudioAttributes(android.media.AudioAttributes);
		method public android.media.AudioFocusRequest.Builder setFocusGain(int);
		method public android.media.AudioFocusRequest.Builder setOnAudioFocusChangeListener(android.media.AudioManager.OnAudioFocusChangeListener);
		method public android.media.AudioFocusRequest.Builder setOnAudioFocusChangeListener(android.media.AudioManager.OnAudioFocusChangeListener, android.os.Handler);
		method public android.media.AudioFocusRequest.Builder setWillPauseWhenDucked(boolean);
		}

api/system-current.txt

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Original line number	Diff line number	Diff line
		@@ -22814,6 +22814,7 @@ package android.media {
		method public android.media.AudioFocusRequest.Builder setAudioAttributes(android.media.AudioAttributes);
		method public android.media.AudioFocusRequest.Builder setFocusGain(int);
		method public android.media.AudioFocusRequest.Builder setLocksFocus(boolean);
		method public android.media.AudioFocusRequest.Builder setOnAudioFocusChangeListener(android.media.AudioManager.OnAudioFocusChangeListener);
		method public android.media.AudioFocusRequest.Builder setOnAudioFocusChangeListener(android.media.AudioManager.OnAudioFocusChangeListener, android.os.Handler);
		method public android.media.AudioFocusRequest.Builder setWillPauseWhenDucked(boolean);
		}

api/test-current.txt

+1 −0

Original line number	Diff line number	Diff line
		@@ -21114,6 +21114,7 @@ package android.media {
		method public android.media.AudioFocusRequest.Builder setAcceptsDelayedFocusGain(boolean);
		method public android.media.AudioFocusRequest.Builder setAudioAttributes(android.media.AudioAttributes);
		method public android.media.AudioFocusRequest.Builder setFocusGain(int);
		method public android.media.AudioFocusRequest.Builder setOnAudioFocusChangeListener(android.media.AudioManager.OnAudioFocusChangeListener);
		method public android.media.AudioFocusRequest.Builder setOnAudioFocusChangeListener(android.media.AudioManager.OnAudioFocusChangeListener, android.os.Handler);
		method public android.media.AudioFocusRequest.Builder setWillPauseWhenDucked(boolean);
		}

media/java/android/media/AudioFocusRequest.java

+124 −16

Original line number	Diff line number	Diff line
		@@ -29,14 +29,104 @@ import android.os.Looper;
		* request and abandon audio focus, respectively
		* with {@link AudioManager#requestAudioFocus(AudioFocusRequest)} and
		* {@link AudioManager#abandonAudioFocusRequest(AudioFocusRequest)}.
		* <p>In the context of describing audio focus, the term "ducking" is used. It describes a temporary
		* lowering of the audio level of an application in response to another application playing audio
		* concurrently. An example is during the playback of driving directions,
		* a user listening to music expects the music to "duck" during the playback of the message
		* announcing directions.
		*
		* <h3>What is audio focus?</h3>
		* <p>Audio focus is a concept introduced in API 8. It is used to convey the fact that a user can
		* only focus on a single audio stream at a time, e.g. listening to music or a podcast, but not
		* both at the same time. In some cases, multiple audio streams can be playing at the same time,
		* but there is only one the user would really listen to (focus on), while the other plays in
		* the background. An example of this is driving directions being spoken while music plays at
		* a reduced volume (a.k.a. ducking).
		* <p>When an application requests audio focus, it expresses its intention to “own” audio focus to
		* play audio. Let’s review the different types of focus requests, the return value after a request,
		* and the responses to a loss.
		* <br><b>Note:<b> applications should not play anything until granted focus.
		*
		* <h3>The different types of focus requests</h3>
		* <p>There are four focus request types. A successful focus request with each will yield different
		* behaviors by the system and the other application that previously held audio focus.
		* <ul>
		* <li>{@link AudioManager#AUDIOFOCUS_GAIN} expresses the fact that your application is now the
		* sole source of audio that the user is listening to. The duration of the audio playback is
		* unknown, and is possibly very long: after the user finishes interacting with your application,
		* (s)he doesn’t expect another audio stream to resume. Examples of uses of this focus gain are
		* for music playback, for a game or a video player.</li>
		*
		* <li>{@link AudioManager#AUDIOFOCUS_GAIN_TRANSIENT} is for a situation when you know your
		* application is temporarily grabbing focus from the current owner, but the user expects playback
		* to go back to where it was once your application no longer requires audio focus. An example is
		* for playing an alarm, or during a VoIP call. The playback is known to be finite: the alarm will
		* time-out or be dismissed, the VoIP call has a beginning and an end. When any of those events
		* ends, and if the user was listening to music when it started, the user expects music to resume,
		* but didn’t wish to listen to both at the same time.</li>
		*
		* <li>{@link AudioManager#AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK}: this focus request type is similar
		* to {@code AUDIOFOCUS_GAIN_TRANSIENT} for the temporary aspect of the focus request, but it also
		* expresses the fact during the time you own focus, you allow another application to keep playing
		* at a reduced volume, “ducked”. Examples are when playing driving directions or notifications,
		* it’s ok for music to keep playing, but not loud enough that it would prevent the directions to
		* be hard to understand. A typical attenuation by the “ducked” application is a factor of 0.2f
		* (or -14dB), that can for instance be applied with {@code MediaPlayer.setVolume(0.2f)} when
		* using this class for playback.</li>
		*
		* <li>{@link AudioManager#AUDIOFOCUS_GAIN_TRANSIENT_EXCLUSIVE} is also for a temporary request,
		* but also expresses that your application expects the device to not play anything else. This is
		* typically used if you are doing audio recording or speech recognition, and don’t want for
		* examples notifications to be played by the system during that time.</li>
		* </ul>
		*
		* <p>An {@code AudioFocusRequest} instance always contains one of the four types of requests
		* explained above. It is passed when building an {@code AudioFocusRequest} instance with its
		* builder in the {@link Builder} constructor {@link Builder#Builder(int)}, or with
		* {@link Builder#setFocusGain(int)} after copying an existing instance with
		* {@link Builder#Builder(AudioFocusRequest)}.
		*
		* <h3>Qualifying your focus request</h3>
		* <h4>Use case requiring a focus request</h4>
		* <p>Any focus request is qualified by the {@link AudioAttributes}
		* (see {@link Builder#setAudioAttributes(AudioAttributes)}) that describe the audio use case that
		* will follow the request (once it's successful or granted). It is recommended to use the
		* same {@code AudioAttributes} for the request as the attributes you are using for audio/media
		* playback.
		* <br>If no attributes are set, default attributes of {@link AudioAttributes#USAGE_MEDIA} are used.
		*
		* <h4>Delayed focus</h4>
		* <p>Audio focus can be "locked" by the system for a number of reasons: during a phone call, when
		* the car to which the device is connected plays an emergency message... To support these
		* situations, the application can request to be notified when its request is fulfilled, by flagging
		* its request as accepting delayed focus, with {@link Builder#setAcceptsDelayedFocusGain(boolean)}.
		* <br>If focus is requested while being locked by the system,
		* {@link AudioManager#requestAudioFocus(AudioFocusRequest)} will return
		* {@link AudioManager#AUDIOFOCUS_REQUEST_DELAYED}. When focus isn't locked anymore, the focus
		* listener set with {@link Builder#setOnAudioFocusChangeListener(OnAudioFocusChangeListener)}
		* or with {@link Builder#setOnAudioFocusChangeListener(OnAudioFocusChangeListener, Handler)} will
		* be called to notify the application it now owns audio focus.
		*
		* <h4>Pausing vs ducking</h4>
		* <p>When an application requested audio focus with
		* {@link AudioManager#AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK}, the system will duck the current focus
		* owner. Note that this behavior is <b>new for Android O<b>, whereas applications targeting SDK
		* up to API 25, applications had to implement the ducking themselves when they received a focus
		* loss of {@link AudioManager#AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK}.
		* <br>But ducking is not always the behavior expected by the user. A typical example is when the
		* device plays driving directions while the user is listening to an audio book or podcast, and
		* expects the audio playback to pause, instead of duck, as it is hard to understand a navigation
		* prompt and spoken content at the same time. Therefore the system will not automatically duck
		* when it detects it would be ducking spoken content: such content is detected when the
		* {@code AudioAttributes} of the player are qualified by
		* {@link AudioAttributes#CONTENT_TYPE_SPEECH}. Refer for instance to
		* {@link AudioAttributes.Builder#setContentType(int)} and
		* {@link MediaPlayer#setAudioAttributes(AudioAttributes)} if you are writing a media playback
		* application for audio book, podcasts... Since the system will not automatically duck applications
		* that play speech, it calls their focus listener instead to notify them of
		* {@link AudioManager#AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK}, so they can pause instead. Note that
		* this behavior is independent of the use of {@code AudioFocusRequest}, but tied to the use
		* of {@code AudioAttributes}.
		* <p>If your application requires pausing instead of ducking for any other reason than playing
		* speech, you can also declare so with {@link Builder#setWillPauseWhenDucked(boolean)}, which will
		* cause the system to call your focus listener instead of automatically ducking.
		*
		*/
		// TODO use this class to provide more documentation about audio focus and the new behaviors
		// describe up to N, and after.
		public final class AudioFocusRequest {

		// default attributes for the request when not specified
		@@ -245,6 +335,27 @@ public final class AudioFocusRequest {
		return this;
		}

		/**
		* Sets the listener called when audio focus changes after being requested with
		* {@link AudioManager#requestAudioFocus(AudioFocusRequest)}, and until being abandoned
		* with {@link AudioManager#abandonAudioFocusRequest(AudioFocusRequest)}.
		* Note that only focus changes (gains and losses) affecting the focus owner are reported,
		* not gains and losses of other focus requesters in the system.<br>
		* Notifications are delivered on the main {@link Looper}.
		* @param listener the listener receiving the focus change notifications.
		* @return this {@code Builder} instance.
		* @throws NullPointerException thrown when a null focus listener is used.
		*/
		public @NonNull Builder setOnAudioFocusChangeListener(
		@NonNull OnAudioFocusChangeListener listener) {
		if (listener == null) {
		throw new NullPointerException("Illegal null focus listener");
		}
		mFocusListener = listener;
		mListenerHandler = null;
		return this;
		}

		/**
		* Sets the listener called when audio focus changes after being requested with
		* {@link AudioManager#requestAudioFocus(AudioFocusRequest)}, and until being abandoned
		@@ -253,17 +364,14 @@ public final class AudioFocusRequest {
		* not gains and losses of other focus requesters in the system.
		* @param listener the listener receiving the focus change notifications.
		* @param handler the {@link Handler} for the thread on which to execute
		* the notifications. If {@code null}, the {@code Handler} associated with the main
		* {@link Looper} will be used.
		* the notifications.
		* @return this {@code Builder} instance.
		* @throws IllegalArgumentException thrown when a non-null handler is used with a null
		* listener.
		* @throws NullPointerException thrown when a null focus listener or handler is used.
		*/
		public @NonNull Builder setOnAudioFocusChangeListener(
		@Nullable OnAudioFocusChangeListener listener, @Nullable Handler handler) {
		if (listener == null && handler != null) {
		throw new IllegalArgumentException(
		"Illegal non-null handler without a focus listener");
		@NonNull OnAudioFocusChangeListener listener, @NonNull Handler handler) {
		if (listener == null \|\| handler == null) {
		throw new NullPointerException("Illegal null focus listener or handler");
		}
		mFocusListener = listener;
		mListenerHandler = handler;
		@@ -272,7 +380,7 @@ public final class AudioFocusRequest {

		/**
		* Sets the {@link AudioAttributes} to be associated with the focus request, and which
		* describe the use case describing why focus is requested.
		* describe the use case for which focus is requested.
		* As the focus requests typically precede audio playback, this information is used on
		* certain platforms to declare the subsequent playback use case. It is therefore good
		* practice to use in this method the same {@code AudioAttributes} as used for