Add seekToPrevious method to Player

PiperOrigin-RevId: 383623440

RELEASENOTES.md

@@ -4,7 +4,7 @@
 
 *   Core Library:
     *   Add `needsReconfiguration` API to the `MediaCodecAdapter` interface.
-    *   Add `seekForward` and `seekBack` methods to `Player`.
+    *   Add `seekForward`, `seekBack` and `seekToPrevious` methods to `Player`.
     *   Make `Player` depend on the new `PlaybackException` class instead of
         `ExoPlaybackException`:
         *   `Player.getPlayerError` now returns a `PlaybackException`.

library/common/src/main/java/com/google/android/exoplayer2/BasePlayer.java

@@ -144,6 +144,24 @@ public abstract class BasePlayer implements Player {
     }
   }
 
+  @Override
+  public final void seekToPrevious() {
+    Timeline timeline = getCurrentTimeline();
+    if (timeline.isEmpty() || isPlayingAd()) {
+      return;
+    }
+    boolean hasPrevious = hasPrevious();
+    if (isCurrentWindowLive() && !isCurrentWindowSeekable()) {
+      if (hasPrevious) {
+        previous();
+      }
+    } else if (hasPrevious && getCurrentPosition() <= MAX_POSITION_FOR_SEEK_TO_PREVIOUS_MS) {
+      previous();
+    } else {
+      seekTo(/* positionMs= */ 0);
+    }
+  }
+
   @Override
   public final boolean hasNext() {
     return getNextWindowIndex() != C.INDEX_UNSET;

library/common/src/main/java/com/google/android/exoplayer2/ForwardingPlayer.java

@@ -277,6 +277,11 @@ public class ForwardingPlayer implements Player {
     player.previous();
   }
 
+  @Override
+  public void seekToPrevious() {
+    player.seekToPrevious();
+  }
+
   @Override
   public boolean hasNext() {
     return player.hasNext();

library/common/src/main/java/com/google/android/exoplayer2/Player.java

@@ -884,6 +884,9 @@ public interface Player {
     default void onMetadata(Metadata metadata) {}
   }
 
+  /** The maximum position for which {@link #seekToPrevious()} seeks to the previous window. */
+  int MAX_POSITION_FOR_SEEK_TO_PREVIOUS_MS = 3000;
+
   /**
    * Playback state. One of {@link #STATE_IDLE}, {@link #STATE_BUFFERING}, {@link #STATE_READY} or
    * {@link #STATE_ENDED}.
@@ -1653,6 +1656,27 @@ public interface Player {
    */
   void previous();
 
+  /**
+   * Seeks to an earlier position in the current or previous window (if available). More precisely:
+   *
+   * <ul>
+   *   <li>If the timeline is empty or seeking is not possible, does nothing.
+   *   <li>Otherwise, if the current window is {@link #isCurrentWindowLive() live} and {@link
+   *       #isCurrentWindowSeekable() unseekable}, then:
+   *       <ul>
+   *         <li>If {@link #hasPrevious() a previous window exists}, seeks to the default position
+   *             of the previous window.
+   *         <li>Otherwise, does nothing.
+   *       </ul>
+   *   <li>Otherwise, if {@link #hasPrevious() a previous window exists} and the {@link
+   *       #getCurrentPosition() current position} is less than {@link
+   *       #MAX_POSITION_FOR_SEEK_TO_PREVIOUS_MS}, seeks to the default position of the previous
+   *       window.
+   *   <li>Otherwise, seeks to 0 in the current window.
+   * </ul>
+   */
+  void seekToPrevious();
+
   /**
    * Returns whether a next window exists, which may depend on the current repeat mode and whether
    * shuffle mode is enabled.

library/core/src/test/java/com/google/android/exoplayer2/ExoPlayerTest.java

@@ -40,6 +40,7 @@ import static com.google.android.exoplayer2.Player.COMMAND_SET_SHUFFLE_MODE;
 import static com.google.android.exoplayer2.Player.COMMAND_SET_SPEED_AND_PITCH;
 import static com.google.android.exoplayer2.Player.COMMAND_SET_VIDEO_SURFACE;
 import static com.google.android.exoplayer2.Player.COMMAND_SET_VOLUME;
+import static com.google.android.exoplayer2.Player.MAX_POSITION_FOR_SEEK_TO_PREVIOUS_MS;
 import static com.google.android.exoplayer2.Player.STATE_ENDED;
 import static com.google.android.exoplayer2.robolectric.RobolectricUtil.runMainLooperUntil;
 import static com.google.android.exoplayer2.robolectric.TestPlayerRunHelper.playUntilPosition;
@@ -10520,6 +10521,30 @@ public final class ExoPlayerTest {
     player.release();
   }
 
+  @Test
+  public void seekToPrevious_closeToStart_seeksToPreviousWindow() {
+    ExoPlayer player = new TestExoPlayerBuilder(context).build();
+    player.addMediaSources(ImmutableList.of(new FakeMediaSource(), new FakeMediaSource()));
+    player.seekTo(/* windowIndex= */ 1, /* positionMs= */ MAX_POSITION_FOR_SEEK_TO_PREVIOUS_MS);
+
+    player.seekToPrevious();
+
+    assertThat(player.getCurrentWindowIndex()).isEqualTo(0);
+    assertThat(player.getCurrentPosition()).isEqualTo(0);
+  }
+
+  @Test
+  public void seekToPrevious_notCloseToStart_seeksToZero() {
+    ExoPlayer player = new TestExoPlayerBuilder(context).build();
+    player.addMediaSources(ImmutableList.of(new FakeMediaSource(), new FakeMediaSource()));
+    player.seekTo(/* windowIndex= */ 1, /* positionMs= */ MAX_POSITION_FOR_SEEK_TO_PREVIOUS_MS + 1);
+
+    player.seekToPrevious();
+
+    assertThat(player.getCurrentWindowIndex()).isEqualTo(1);
+    assertThat(player.getCurrentPosition()).isEqualTo(0);
+  }
+
   @Test
   public void stop_doesNotCallOnPositionDiscontinuity() throws Exception {
     ExoPlayer player = new TestExoPlayerBuilder(context).build();