SessionCallback

abstract class SessionCallback

<init>

SessionCallback()

Callback to be called for all incoming commands from MediaControllers.

If it's not set, the session will accept all controllers and all incoming commands by default.

onCommandRequest

open fun onCommandRequest(
    @NonNull session: MediaSession, 
    @NonNull controller: MediaSession.ControllerInfo, 
    @NonNull command: SessionCommand
): Int

Called when a controller sent a command which will be sent directly to one of the following:

• SessionPlayer
• android.media.AudioManager

Return SessionResult#RESULT_SUCCESS to proceed the command. If something else is returned, command wouldn't be sent and the controller would receive the code with it.

Parameters
session	MediaSession: the session for this event
controller	MediaSession.ControllerInfo: controller information.
command	SessionCommand: a command. This method will be called for every single command.

Return
Int	RESULT_SUCCESS if you want to proceed with incoming command. Another code for ignore.

onConnect

@Nullable open fun onConnect(
    @NonNull session: MediaSession, 
    @NonNull controller: MediaSession.ControllerInfo
): SessionCommandGroup?

Called when a controller is created for this session. Return allowed commands for controller. By default it allows all connection requests and commands.

You can reject the connection by return null. In that case, the controller receives MediaController.ControllerCallback#onDisconnected(MediaController) and cannot be used.

The controller hasn't connected yet in this method, so calls to the controller (e.g. sendCustomCommand, setCustomLayout) would be ignored. Override onPostConnect for the custom initialization for the controller instead.

Parameters
session	MediaSession: the session for this event
controller	MediaSession.ControllerInfo: controller information.

Return
SessionCommandGroup?	allowed commands. Can be null to reject connection.

onCreateMediaItem

@Nullable open fun onCreateMediaItem(
    @NonNull session: MediaSession, 
    @NonNull controller: MediaSession.ControllerInfo, 
    @NonNull mediaId: String
): MediaItem?

Called when a controller has sent a command with a MediaItem to add a new media item to this session. Being specific, this will be called for following APIs.

1. MediaController#addPlaylistItem(int, String)
2. MediaController#replacePlaylistItem(int, String)
3. MediaController#setPlaylist(List, MediaMetadata)
4. MediaController#setMediaItem(String)

Override this to translate incoming mediaId to a MediaItem to be understood by your player. For example, a player may only understand androidx.media2.common.FileMediaItem, UriMediaItem, and CallbackMediaItem. Check the documentation of the player that you're using.

If the given media ID is valid, you should return the media item with the given media ID. If the ID doesn't match, an RuntimeException will be thrown. You may return null if the given item is invalid. Here's the behavior when it happens.

Controller command	Behavior when null is returned
addPlaylistItem	Ignore
replacePlaylistItem	Ignore
setPlaylist	Ignore null items, and build a list with non-null items. Call SessionPlayer#setPlaylist(List, MediaMetadata) with the list
setMediaItem	Ignore

This will be called on the same thread where onCommandRequest and commands with the media controller will be executed.

Default implementation returns the null.

Parameters
session	MediaSession: the session for this event
controller	MediaSession.ControllerInfo: controller information
mediaId	String: non-empty media id for creating item with

Return
MediaItem?	translated media item for player with the mediaId. Can be null to ignore.

onCustomCommand

@NonNull open fun onCustomCommand(
    @NonNull session: MediaSession, 
    @NonNull controller: MediaSession.ControllerInfo, 
    @NonNull customCommand: SessionCommand, 
    @Nullable args: Bundle?
): SessionResult

Called when a controller sent a custom command through MediaController#sendCustomCommand(SessionCommand, Bundle).

Interoperability: This would be also called by . If so, extra from sendCustomAction will be considered as args and customCommand would have null extra.

Parameters
session	MediaSession: the session for this event
controller	MediaSession.ControllerInfo: controller information
customCommand	SessionCommand: custom command.
args	Bundle?: optional arguments

Return
SessionResult	result of handling custom command. A runtime exception will be thrown if null is returned.

onDisconnected

open fun onDisconnected(
    @NonNull session: MediaSession, 
    @NonNull controller: MediaSession.ControllerInfo
): Unit

Called when a controller is disconnected.

Interoperability: For legacy controller, this is called when the controller doesn't send any command for a while. It's because there were no explicit disconnect API in legacy controller API.

Parameters
session	MediaSession: the session for this event
controller	MediaSession.ControllerInfo: controller information

onFastForward

open fun onFastForward(
    @NonNull session: MediaSession, 
    @NonNull controller: MediaSession.ControllerInfo
): Int

Called when a controller called MediaController#fastForward().

It can be implemented in many ways. For example, it can be implemented by seeking forward once, series of seeking forward, or increasing playback speed.

Parameters
session	MediaSession: the session for this event
controller	MediaSession.ControllerInfo: controller information

onPostConnect

open fun onPostConnect(
    @NonNull session: MediaSession, 
    @NonNull controller: MediaSession.ControllerInfo
): Unit

Called immediately after a controller is connected. This is a convenient method to add custom initialization between the session and a controller.

Note that calls to the controller (e.g. sendCustomCommand, setCustomLayout) work here but don't work in onConnect because the controller hasn't connected yet in onConnect.

Parameters
session	MediaSession: the session for this event
controller	MediaSession.ControllerInfo: controller information.

onRewind

open fun onRewind(
    @NonNull session: MediaSession, 
    @NonNull controller: MediaSession.ControllerInfo
): Int

Called when a controller called MediaController#rewind().

It can be implemented in many ways. For example, it can be implemented by seeking backward once, series of seeking backward, or decreasing playback speed.

Parameters
session	MediaSession: the session for this event
controller	MediaSession.ControllerInfo: controller information

onSetMediaUri

open fun onSetMediaUri(
    @NonNull session: MediaSession, 
    @NonNull controller: MediaSession.ControllerInfo, 
    @NonNull uri: Uri, 
    @Nullable extras: Bundle?
): Int

Called when a controller requested to set the specific media item(s) represented by a URI through MediaController#setMediaUri(Uri, Bundle).

The implementation should create proper media item(s) for the given uri and call SessionPlayer#setMediaItem or SessionPlayer#setPlaylist.

When MediaControllerCompat is connected and sends commands with following methods, the uri would have the following patterns:

Method	Uri pattern
prepareFromUri	The uri passed as argument
prepareFromMediaId	androidx://media2-session/prepareFromMediaId?id=[mediaId]
prepareFromSearch	androidx://media2-session/prepareFromSearch?query=[query]
playFromUri	The uri passed as argument
playFromMediaId	androidx://media2-session/playFromMediaId?id=[mediaId]
playFromSearch	androidx://media2-session/playFromSearch?query=[query]

SessionPlayer#prepare() or SessionPlayer#play() would be followed if this is called by above methods.

Parameters
session	MediaSession: the session for this event
controller	MediaSession.ControllerInfo: controller information
uri	Uri: uri
extras	Bundle?: optional extra bundle

onSetRating

open fun onSetRating(
    @NonNull session: MediaSession, 
    @NonNull controller: MediaSession.ControllerInfo, 
    @NonNull mediaId: String, 
    @NonNull rating: Rating
): Int

Called when a controller set rating of a media item through MediaController#setRating(String, Rating).

To allow setting user rating for a MediaItem, the media item's metadata should have Rating with the key MediaMetadata#METADATA_KEY_USER_RATING, in order to provide possible rating style for controller. Controller will follow the rating style.

Parameters
session	MediaSession: the session for this event
controller	MediaSession.ControllerInfo: controller information
mediaId	String: non-empty media id
rating	Rating: new rating from the controller

onSkipBackward

open fun onSkipBackward(
    @NonNull session: MediaSession, 
    @NonNull controller: MediaSession.ControllerInfo
): Int

Called when a controller called MediaController#skipBackward().

It's recommended to seek backward within the current media item, but its detail may vary. For example, it can be implemented by seeking backward for the fixed amount of seconds, or seeking backward to the nearest bookmark.

Parameters
session	MediaSession: the session for this event
controller	MediaSession.ControllerInfo: controller information

onSkipForward

open fun onSkipForward(
    @NonNull session: MediaSession, 
    @NonNull controller: MediaSession.ControllerInfo
): Int

Called when a controller called MediaController#skipForward().

It's recommended to seek forward within the current media item, but its detail may vary. For example, it can be implemented by seeking forward for the fixed amount of seconds, or seeking forward to the nearest bookmark.

Parameters
session	MediaSession: the session for this event
controller	MediaSession.ControllerInfo: controller information