Hide media notification when nothing to play

With this change, the MediaNotificationManager stops MediaSessionService
and hides any notifications if the player has no media items or the
player hasn't been prepared yet.

PiperOrigin-RevId: 435349363

libraries/session/src/main/java/androidx/media3/session/MediaNotificationManager.java

@@ -15,6 +15,8 @@
  */
 package androidx.media3.session;
 
+import static androidx.media3.common.util.Assertions.checkStateNotNull;
+
 import android.app.Notification;
 import android.content.Intent;
 import android.os.Bundle;
@@ -25,6 +27,7 @@ import androidx.core.app.NotificationManagerCompat;
 import androidx.core.content.ContextCompat;
 import androidx.media3.common.Player;
 import androidx.media3.common.util.Util;
+import com.google.common.util.concurrent.Futures;
 import com.google.common.util.concurrent.ListenableFuture;
 import java.util.HashMap;
 import java.util.List;
@@ -50,6 +53,7 @@ import java.util.concurrent.TimeoutException;
   private final Map<MediaSession, ListenableFuture<MediaController>> controllerMap;
 
   private int totalNotificationCount;
+  @Nullable private MediaNotification mediaNotification;
 
   public MediaNotificationManager(
       MediaSessionService mediaSessionService,
@@ -122,13 +126,13 @@ import java.util.concurrent.TimeoutException;
 
     MediaController mediaController;
     try {
-      mediaController = controllerFuture.get(0, TimeUnit.MILLISECONDS);
-    } catch (ExecutionException | InterruptedException | TimeoutException e) {
+      mediaController = checkStateNotNull(Futures.getDone(controllerFuture));
+    } catch (ExecutionException e) {
       // We should never reach this point.
       throw new IllegalStateException(e);
     }
 
-    int notificationSequence = ++this.totalNotificationCount;
+    int notificationSequence = ++totalNotificationCount;
     MediaNotification.Provider.Callback callback =
         notification ->
             mainExecutor.execute(
@@ -141,45 +145,68 @@ import java.util.concurrent.TimeoutException;
 
   private void onNotificationUpdated(
       int notificationSequence, MediaSession session, MediaNotification mediaNotification) {
-    if (notificationSequence == this.totalNotificationCount) {
+    if (notificationSequence == totalNotificationCount) {
       updateNotification(session, mediaNotification);
     }
   }
 
   private void updateNotification(MediaSession session, MediaNotification mediaNotification) {
-    int id = mediaNotification.notificationId;
-    Notification notification = mediaNotification.notification;
-
     if (Util.SDK_INT >= 21) {
       // Call Notification.MediaStyle#setMediaSession() indirectly.
       android.media.session.MediaSession.Token fwkToken =
           (android.media.session.MediaSession.Token)
               session.getSessionCompat().getSessionToken().getToken();
-      notification.extras.putParcelable(Notification.EXTRA_MEDIA_SESSION, fwkToken);
+      mediaNotification.notification.extras.putParcelable(
+          Notification.EXTRA_MEDIA_SESSION, fwkToken);
     }
 
+    this.mediaNotification = mediaNotification;
     Player player = session.getPlayer();
-    if (player.getPlayWhenReady()) {
+    if (player.getPlayWhenReady() && canStartPlayback(player)) {
       ContextCompat.startForegroundService(mediaSessionService, startSelfIntent);
-      mediaSessionService.startForeground(id, notification);
+      mediaSessionService.startForeground(
+          mediaNotification.notificationId, mediaNotification.notification);
     } else {
-      stopForegroundServiceIfNeeded();
-      notificationManagerCompat.notify(id, notification);
+      maybeStopForegroundService(/* removeNotifications= */ false);
+      notificationManagerCompat.notify(
+          mediaNotification.notificationId, mediaNotification.notification);
     }
   }
 
-  private void stopForegroundServiceIfNeeded() {
+  /**
+   * Stops the service from the foreground, if no player is actively playing content.
+   *
+   * @param removeNotifications Whether to remove notifications, if the service is stopped from the
+   *     foreground.
+   */
+  private void maybeStopForegroundService(boolean removeNotifications) {
     List<MediaSession> sessions = mediaSessionService.getSessions();
     for (int i = 0; i < sessions.size(); i++) {
       Player player = sessions.get(i).getPlayer();
-      if (player.getPlayWhenReady()) {
+      if (player.getPlayWhenReady() && canStartPlayback(player)) {
         return;
       }
     }
-    // Calling stopForeground(true) is a workaround for pre-L devices which prevents
-    // the media notification from being undismissable.
-    boolean shouldRemoveNotification = Util.SDK_INT < 21;
-    mediaSessionService.stopForeground(shouldRemoveNotification);
+    // To hide the notification on all API levels, we need to call both Service.stopForeground(true)
+    // and notificationManagerCompat.cancelAll(). For pre-L devices, we must also call
+    // Service.stopForeground(true) anyway as a workaround that prevents the media notification from
+    // being undismissable.
+    mediaSessionService.stopForeground(removeNotifications || Util.SDK_INT < 21);
+    if (removeNotifications && mediaNotification != null) {
+      notificationManagerCompat.cancel(mediaNotification.notificationId);
+      // Update the notification count so that if a pending notification callback arrives (e.g., a
+      // bitmap is loaded), we don't show the notification.
+      totalNotificationCount++;
+      mediaNotification = null;
+    }
+  }
+
+  /**
+   * Returns whether {@code player} can start playback and therefore we should present a
+   * notification for this player.
+   */
+  private static boolean canStartPlayback(Player player) {
+    return player.getPlaybackState() != Player.STATE_IDLE && !player.getCurrentTimeline().isEmpty();
   }
 
   private final class MediaControllerListener implements MediaController.Listener, Player.Listener {
@@ -190,11 +217,20 @@ import java.util.concurrent.TimeoutException;
     }
 
     public void onConnected() {
-      updateNotification(session);
+      if (canStartPlayback(session.getPlayer())) {
+        updateNotification(session);
+      }
     }
 
     @Override
     public void onEvents(Player player, Player.Events events) {
+      if (!canStartPlayback(player)) {
+        maybeStopForegroundService(/* removeNotifications= */ true);
+        return;
+      }
+
+      // Limit the events on which we may update the notification to ensure we don't update the
+      // notification too frequently, otherwise the system may suppress notifications.
       if (events.containsAny(
           Player.EVENT_PLAYBACK_STATE_CHANGED,
           Player.EVENT_PLAY_WHEN_READY_CHANGED,
@@ -206,7 +242,7 @@ import java.util.concurrent.TimeoutException;
     @Override
     public void onDisconnected(MediaController controller) {
       mediaSessionService.removeSession(session);
-      stopForegroundServiceIfNeeded();
+      maybeStopForegroundService(/* removeNotifications= */ true);
     }
   }
 }