Add getNextWindowIndex to Timeline

(Preparation for Repeat Toggle Function - GitHub Issue #2577)

In addition, Timeline now also got a getPreviousWindowIndex and a
getNextPeriodIndex method with default implementations.

Changed ExoPlayerImplInternal and PlaybackControlView to use these
methods at all occurances of period and window index operations.

Note: Does not include repeat mode yet and no timelines are actually
using it so far. Please wait for the next CLs for this.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=154520664

library/core/src/main/java/com/google/android/exoplayer2/ExoPlayer.java

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2;
 
+import android.support.annotation.IntDef;
 import android.support.annotation.Nullable;
 import com.google.android.exoplayer2.audio.MediaCodecAudioRenderer;
 import com.google.android.exoplayer2.metadata.MetadataRenderer;
@@ -30,6 +31,8 @@ import com.google.android.exoplayer2.trackselection.TrackSelectionArray;
 import com.google.android.exoplayer2.trackselection.TrackSelector;
 import com.google.android.exoplayer2.upstream.DataSource;
 import com.google.android.exoplayer2.video.MediaCodecVideoRenderer;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
 
 /**
  * An extensible media player exposing traditional high-level media player functionality, such as
@@ -251,6 +254,17 @@ public interface ExoPlayer {
    */
   int STATE_ENDED = 4;
 
+  /**
+   * Repeat modes for playback.
+   */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({REPEAT_MODE_OFF})
+  @interface RepeatMode {}
+  /**
+   * Normal playback without repetition.
+   */
+  int REPEAT_MODE_OFF = 0;
+
   /**
    * Register a listener to receive events from the player. The listener's methods will be called on
    * the thread that was used to construct the player.

library/core/src/main/java/com/google/android/exoplayer2/ExoPlayerImplInternal.java

@@ -948,10 +948,7 @@ import java.io.IOException;
     }
 
     // The current period is in the new timeline. Update the holder and playbackInfo.
-    timeline.getPeriod(periodIndex, period);
-    boolean isLastPeriod = periodIndex == timeline.getPeriodCount() - 1
-        && !timeline.getWindow(period.windowIndex, window).isDynamic;
-    periodHolder.setIndex(periodIndex, isLastPeriod);
+    periodHolder.setIndex(periodIndex, isLastPeriod(periodIndex));
     boolean seenReadingPeriod = periodHolder == readingPeriodHolder;
     if (periodIndex != playbackInfo.periodIndex) {
       playbackInfo = playbackInfo.copyWithPeriodIndex(periodIndex);
@@ -962,10 +959,10 @@ import java.io.IOException;
     while (periodHolder.next != null) {
       MediaPeriodHolder previousPeriodHolder = periodHolder;
       periodHolder = periodHolder.next;
-      periodIndex++;
+      periodIndex = timeline.getNextPeriodIndex(periodIndex, period, window,
+          ExoPlayer.REPEAT_MODE_OFF);
+      boolean isLastPeriod = isLastPeriod(periodIndex);
       timeline.getPeriod(periodIndex, period, true);
-      isLastPeriod = periodIndex == timeline.getPeriodCount() - 1
-          && !timeline.getWindow(period.windowIndex, window).isDynamic;
       if (periodHolder.uid.equals(period.uid)) {
         // The holder is consistent with the new timeline. Update its index and continue.
         periodHolder.setIndex(periodIndex, isLastPeriod);
@@ -1023,13 +1020,22 @@ import java.io.IOException;
   private int resolveSubsequentPeriod(int oldPeriodIndex, Timeline oldTimeline,
       Timeline newTimeline) {
     int newPeriodIndex = C.INDEX_UNSET;
-    while (newPeriodIndex == C.INDEX_UNSET && oldPeriodIndex < oldTimeline.getPeriodCount() - 1) {
+    int maxIterations = oldTimeline.getPeriodCount();
+    for (int i = 0; i < maxIterations && newPeriodIndex == C.INDEX_UNSET; i++) {
+      oldPeriodIndex = oldTimeline.getNextPeriodIndex(oldPeriodIndex, period, window,
+          ExoPlayer.REPEAT_MODE_OFF);
       newPeriodIndex = newTimeline.getIndexOfPeriod(
-          oldTimeline.getPeriod(++oldPeriodIndex, period, true).uid);
+          oldTimeline.getPeriod(oldPeriodIndex, period, true).uid);
     }
     return newPeriodIndex;
   }
 
+  private boolean isLastPeriod(int periodIndex) {
+    int windowIndex = timeline.getPeriod(periodIndex, period).windowIndex;
+    return !timeline.getWindow(windowIndex, window).isDynamic
+        && timeline.isLastPeriod(periodIndex, period, window, ExoPlayer.REPEAT_MODE_OFF);
+  }
+
   /**
    * Converts a {@link SeekPosition} into the corresponding (periodIndex, periodPositionUs) for the
    * internal timeline.
@@ -1240,7 +1246,8 @@ import java.io.IOException;
         // We are already buffering the maximum number of periods ahead.
         return;
       }
-      newLoadingPeriodIndex = loadingPeriodHolder.index + 1;
+      newLoadingPeriodIndex = timeline.getNextPeriodIndex(loadingPeriodHolder.index, period, window,
+          ExoPlayer.REPEAT_MODE_OFF);
     }
 
     if (newLoadingPeriodIndex >= timeline.getPeriodCount()) {
@@ -1283,9 +1290,8 @@ import java.io.IOException;
         ? newLoadingPeriodStartPositionUs + RENDERER_TIMESTAMP_OFFSET_US
         : (loadingPeriodHolder.getRendererOffset()
             + timeline.getPeriod(loadingPeriodHolder.index, period).getDurationUs());
+    boolean isLastPeriod = isLastPeriod(newLoadingPeriodIndex);
     timeline.getPeriod(newLoadingPeriodIndex, period, true);
-    boolean isLastPeriod = newLoadingPeriodIndex == timeline.getPeriodCount() - 1
-        && !timeline.getWindow(period.windowIndex, window).isDynamic;
     MediaPeriodHolder newPeriodHolder = new MediaPeriodHolder(renderers, rendererCapabilities,
         rendererPositionOffsetUs, trackSelector, loadControl, mediaSource, period.uid,
         newLoadingPeriodIndex, isLastPeriod, newLoadingPeriodStartPositionUs);

library/core/src/main/java/com/google/android/exoplayer2/Timeline.java

@@ -136,6 +136,54 @@ public abstract class Timeline {
    */
   public abstract int getWindowCount();
 
+  /**
+   * Returns the index of the window after the window at index {@code windowIndex} depending on the
+   * {@code repeatMode}.
+   *
+   * @param windowIndex Index of a window in the timeline.
+   * @param repeatMode A repeat mode.
+   * @return The index of the next window, or {@link C#INDEX_UNSET} if this is the last window.
+   */
+  public int getNextWindowIndex(int windowIndex, @ExoPlayer.RepeatMode int repeatMode) {
+    return windowIndex == getWindowCount() - 1 ? C.INDEX_UNSET : windowIndex + 1;
+  }
+
+  /**
+   * Returns the index of the window before the window at index {@code windowIndex} depending on the
+   * {@code repeatMode}.
+   *
+   * @param windowIndex Index of a window in the timeline.
+   * @param repeatMode A repeat mode.
+   * @return The index of the previous window, or {@link C#INDEX_UNSET} if this is the first window.
+   */
+  public int getPreviousWindowIndex(int windowIndex, @ExoPlayer.RepeatMode int repeatMode) {
+    return windowIndex == 0 ? C.INDEX_UNSET : windowIndex - 1;
+  }
+
+  /**
+   * Returns whether the given window is the last window of the timeline depending on the
+   * {@code repeatMode}.
+   *
+   * @param windowIndex A window index.
+   * @param repeatMode A repeat mode.
+   * @return Whether the window of the given index is the last window of the timeline.
+   */
+  public final boolean isLastWindow(int windowIndex, @ExoPlayer.RepeatMode int repeatMode) {
+    return getNextWindowIndex(windowIndex, repeatMode) == C.INDEX_UNSET;
+  }
+
+  /**
+   * Returns whether the given window is the first window of the timeline depending on the
+   * {@code repeatMode}.
+   *
+   * @param windowIndex A window index.
+   * @param repeatMode A repeat mode.
+   * @return Whether the window of the given index is the first window of the timeline.
+   */
+  public final boolean isFirstWindow(int windowIndex, @ExoPlayer.RepeatMode int repeatMode) {
+    return getPreviousWindowIndex(windowIndex, repeatMode) == C.INDEX_UNSET;
+  }
+
   /**
    * Populates a {@link Window} with data for the window at the specified index. Does not populate
    * {@link Window#id}.
@@ -180,6 +228,44 @@ public abstract class Timeline {
    */
   public abstract int getPeriodCount();
 
+  /**
+   * Returns the index of the period after the period at index {@code periodIndex} depending on the
+   * {@code repeatMode}.
+   *
+   * @param periodIndex Index of a period in the timeline.
+   * @param period A {@link Period} to be used internally. Must not be null.
+   * @param window A {@link Window} to be used internally. Must not be null.
+   * @param repeatMode A repeat mode.
+   * @return The index of the next period, or {@link C#INDEX_UNSET} if this is the last period.
+   */
+  public final int getNextPeriodIndex(int periodIndex, Period period, Window window,
+      @ExoPlayer.RepeatMode int repeatMode) {
+    int windowIndex = getPeriod(periodIndex, period).windowIndex;
+    if (getWindow(windowIndex, window).lastPeriodIndex == periodIndex) {
+      int nextWindowIndex = getNextWindowIndex(windowIndex, repeatMode);
+      if (nextWindowIndex == C.INDEX_UNSET) {
+        return C.INDEX_UNSET;
+      }
+      return getWindow(nextWindowIndex, window).firstPeriodIndex;
+    }
+    return periodIndex + 1;
+  }
+
+  /**
+   * Returns whether the given period is the last period of the timeline depending on the
+   * {@code repeatMode}.
+   *
+   * @param periodIndex A period index.
+   * @param period A {@link Period} to be used internally. Must not be null.
+   * @param window A {@link Window} to be used internally. Must not be null.
+   * @param repeatMode A repeat mode.
+   * @return Whether the period of the given index is the last period of the timeline.
+   */
+  public final boolean isLastPeriod(int periodIndex, Period period, Window window,
+      @ExoPlayer.RepeatMode int repeatMode) {
+    return getNextPeriodIndex(periodIndex, period, window, repeatMode) == C.INDEX_UNSET;
+  }
+
   /**
    * Populates a {@link Period} with data for the period at the specified index. Does not populate
    * {@link Period#id} and {@link Period#uid}.

library/ui/src/main/java/com/google/android/exoplayer2/ui/PlaybackControlView.java

@@ -529,8 +529,10 @@ public class PlaybackControlView extends FrameLayout {
       int windowIndex = player.getCurrentWindowIndex();
       timeline.getWindow(windowIndex, window);
       isSeekable = window.isSeekable;
-      enablePrevious = windowIndex > 0 || isSeekable || !window.isDynamic;
-      enableNext = (windowIndex < timeline.getWindowCount() - 1) || window.isDynamic;
+      enablePrevious = !timeline.isFirstWindow(windowIndex, ExoPlayer.REPEAT_MODE_OFF)
+          || isSeekable || !window.isDynamic;
+      enableNext = !timeline.isLastWindow(windowIndex, ExoPlayer.REPEAT_MODE_OFF)
+          || window.isDynamic;
       if (timeline.getPeriod(player.getCurrentPeriodIndex(), period).isAd) {
         // Always hide player controls during ads.
         hide();
@@ -680,9 +682,12 @@ public class PlaybackControlView extends FrameLayout {
     }
     int windowIndex = player.getCurrentWindowIndex();
     timeline.getWindow(windowIndex, window);
-    if (windowIndex > 0 && (player.getCurrentPosition() <= MAX_POSITION_FOR_SEEK_TO_PREVIOUS
+    int previousWindowIndex = timeline.getPreviousWindowIndex(windowIndex,
+        ExoPlayer.REPEAT_MODE_OFF);
+    if (previousWindowIndex != C.INDEX_UNSET
+        && (player.getCurrentPosition() <= MAX_POSITION_FOR_SEEK_TO_PREVIOUS
         || (window.isDynamic && !window.isSeekable))) {
-      seekTo(windowIndex - 1, C.TIME_UNSET);
+      seekTo(previousWindowIndex, C.TIME_UNSET);
     } else {
       seekTo(0);
     }
@@ -694,8 +699,9 @@ public class PlaybackControlView extends FrameLayout {
       return;
     }
     int windowIndex = player.getCurrentWindowIndex();
-    if (windowIndex < timeline.getWindowCount() - 1) {
-      seekTo(windowIndex + 1, C.TIME_UNSET);
+    int nextWindowIndex = timeline.getNextWindowIndex(windowIndex, ExoPlayer.REPEAT_MODE_OFF);
+    if (nextWindowIndex != C.INDEX_UNSET) {
+      seekTo(nextWindowIndex, C.TIME_UNSET);
     } else if (timeline.getWindow(windowIndex, window, false).isDynamic) {
       seekTo(windowIndex, C.TIME_UNSET);
     }