media/java/android/media/session/MediaSessionManager.java

/*
 * Copyright (C) 2014 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.media.session;

import android.content.ComponentName;
import android.content.Context;
import android.media.session.ISessionManager;
import android.os.IBinder;
import android.os.RemoteException;
import android.os.ServiceManager;
import android.os.UserHandle;
import android.service.notification.NotificationListenerService;
import android.util.Log;
import android.view.KeyEvent;

import java.util.ArrayList;
import java.util.List;

/**
 * MediaSessionManager allows the creation and control of MediaSessions in the
 * system. A MediaSession enables publishing information about ongoing media and
 * interacting with MediaControllers and MediaRoutes.
 * <p>
 * Use <code>Context.getSystemService(Context.MEDIA_SESSION_SERVICE)</code> to
 * get an instance of this class.
 * <p>
 *
 * @see MediaSession
 * @see MediaController
 */
public final class MediaSessionManager {
    private static final String TAG = "SessionManager";

    private final ISessionManager mService;

    private Context mContext;

    /**
     * @hide
     */
    public MediaSessionManager(Context context) {
        // Consider rewriting like DisplayManagerGlobal
        // Decide if we need context
        mContext = context;
        IBinder b = ServiceManager.getService(Context.MEDIA_SESSION_SERVICE);
        mService = ISessionManager.Stub.asInterface(b);
    }

    /**
     * Creates a new session.
     *
     * @param tag A short name for debugging purposes
     * @return a {@link MediaSession} for the new session
     */
    public MediaSession createSession(String tag) {
        return createSessionAsUser(tag, UserHandle.myUserId());
    }

    /**
     * Creates a new session as the specified user. To create a session as a
     * user other than your own you must hold the
     * {@link android.Manifest.permission#INTERACT_ACROSS_USERS_FULL}
     * permission.
     *
     * @param tag A short name for debugging purposes
     * @param userId The user id to create the session as.
     * @return a {@link MediaSession} for the new session
     * @hide
     */
    public MediaSession createSessionAsUser(String tag, int userId) {
        try {
            MediaSession.CallbackStub cbStub = new MediaSession.CallbackStub();
            MediaSession session = new MediaSession(mService
                    .createSession(mContext.getPackageName(), cbStub, tag, userId), cbStub);
            cbStub.setMediaSession(session);

            return session;
        } catch (RemoteException e) {
            Log.e(TAG, "Failed to create session: ", e);
            return null;
        }
    }

    /**
     * Get a list of controllers for all ongoing sessions. The controllers will
     * be provided in priority order with the most important controller at index
     * 0.
     * <p>
     * This requires the android.Manifest.permission.MEDIA_CONTENT_CONTROL
     * permission be held by the calling app. You may also retrieve this list if
     * your app is an enabled notification listener using the
     * {@link NotificationListenerService} APIs, in which case you must pass the
     * {@link ComponentName} of your enabled listener.
     *
     * @param notificationListener The enabled notification listener component.
     *            May be null.
     * @return A list of controllers for ongoing sessions
     * @hide
     */
    public List<MediaController> getActiveSessions(ComponentName notificationListener) {
        return getActiveSessionsForUser(notificationListener, UserHandle.myUserId());
    }

    /**
     * Get active sessions for a specific user. To retrieve actions for a user
     * other than your own you must hold the
     * {@link android.Manifest.permission#INTERACT_ACROSS_USERS_FULL} permission
     * in addition to any other requirements. If you are an enabled notification
     * listener you may only get sessions for the users you are enabled for.
     *
     * @param notificationListener The enabled notification listener component.
     *            May be null.
     * @param userId The user id to fetch sessions for.
     * @return A list of controllers for ongoing sessions.
     * @hide
     */
    public List<MediaController> getActiveSessionsForUser(ComponentName notificationListener,
            int userId) {
        ArrayList<MediaController> controllers = new ArrayList<MediaController>();
        try {
            List<IBinder> binders = mService.getSessions(notificationListener, userId);
            int size = binders.size();
            for (int i = 0; i < size; i++) {
                MediaController controller = MediaController.fromBinder(ISessionController.Stub
                        .asInterface(binders.get(i)));
                controllers.add(controller);
            }
        } catch (RemoteException e) {
            Log.e(TAG, "Failed to get active sessions: ", e);
        }
        return controllers;
    }

    /**
     * Add a listener to be notified when the list of active sessions
     * changes.This requires the
     * android.Manifest.permission.MEDIA_CONTENT_CONTROL permission be held by
     * the calling app. You may also retrieve this list if your app is an
     * enabled notification listener using the
     * {@link NotificationListenerService} APIs, in which case you must pass the
     * {@link ComponentName} of your enabled listener.
     *
     * @param sessionListener The listener to add.
     * @param notificationListener The enabled notification listener component.
     *            May be null.
     * @param userId The userId to listen for changes on.
     * @hide
     */
    public void addActiveSessionsListener(SessionListener sessionListener,
            ComponentName notificationListener, int userId) {
        if (sessionListener == null) {
            throw new IllegalArgumentException("listener may not be null");
        }
        try {
            mService.addSessionsListener(sessionListener.mStub, notificationListener, userId);
        } catch (RemoteException e) {
            Log.e(TAG, "Error in addActiveSessionsListener.", e);
        }
    }

    /**
     * Stop receiving active sessions updates on the specified listener.
     *
     * @param listener The listener to remove.
     * @hide
     */
    public void removeActiveSessionsListener(SessionListener listener) {
        if (listener == null) {
            throw new IllegalArgumentException("listener may not be null");
        }
        try {
            mService.removeSessionsListener(listener.mStub);
        } catch (RemoteException e) {
            Log.e(TAG, "Error in removeActiveSessionsListener.", e);
        }
    }

    /**
     * Send a media key event. The receiver will be selected automatically.
     *
     * @param keyEvent The KeyEvent to send.
     * @hide
     */
    public void dispatchMediaKeyEvent(KeyEvent keyEvent) {
        dispatchMediaKeyEvent(keyEvent, false);
    }

    /**
     * Send a media key event. The receiver will be selected automatically.
     *
     * @param keyEvent The KeyEvent to send
     * @param needWakeLock true if a wake lock should be held while sending the
     *            key
     * @hide
     */
    public void dispatchMediaKeyEvent(KeyEvent keyEvent, boolean needWakeLock) {
        try {
            mService.dispatchMediaKeyEvent(keyEvent, needWakeLock);
        } catch (RemoteException e) {
            Log.e(TAG, "Failed to send key event.", e);
        }
    }

    /**
     * Dispatch an adjust volume request to the system. It will be routed to the
     * most relevant stream/session.
     *
     * @param suggestedStream The stream to fall back to if there isn't a
     *            relevant stream
     * @param delta The amount to adjust the volume by.
     * @param flags Any flags to include with the volume change.
     * @hide
     */
    public void dispatchAdjustVolumeBy(int suggestedStream, int delta, int flags) {
        try {
            mService.dispatchAdjustVolumeBy(suggestedStream, delta, flags);
        } catch (RemoteException e) {
            Log.e(TAG, "Failed to send adjust volume.", e);
        }
    }

    /**
     * Listens for changes to the list of active sessions. This can be added
     * using {@link #addActiveSessionsListener}.
     *
     * @hide
     */
    public static abstract class SessionListener {
        /**
         * Called when the list of active sessions has changed. This can be due
         * to a session being added or removed or the order of sessions
         * changing. The controllers will be provided in priority order with the
         * most important controller at index 0.
         *
         * @param controllers The updated list of controllers for the user that
         *            changed.
         */
        public abstract void onActiveSessionsChanged(List<MediaController> controllers);

        private final IActiveSessionsListener.Stub mStub = new IActiveSessionsListener.Stub() {
            @Override
            public void onActiveSessionsChanged(List<MediaSessionToken> tokens)
                    throws RemoteException {
                ArrayList<MediaController> controllers = new ArrayList<MediaController>();
                int size = tokens.size();
                for (int i = 0; i < size; i++) {
                    controllers.add(MediaController.fromToken(tokens.get(i)));
                }
                SessionListener.this.onActiveSessionsChanged(controllers);
            }
        };
    }
}