Add TrackSelection.Factory createTrackSelections

createTrackSelections decides whether to create an adaptive or a fixed track seletion to create.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=222231011

library/core/src/main/java/com/google/android/exoplayer2/trackselection/TrackSelection.java

@@ -22,7 +22,9 @@ import com.google.android.exoplayer2.source.TrackGroup;
 import com.google.android.exoplayer2.source.chunk.MediaChunk;
 import com.google.android.exoplayer2.source.chunk.MediaChunkIterator;
 import com.google.android.exoplayer2.upstream.BandwidthMeter;
+import com.google.android.exoplayer2.util.Assertions;
 import java.util.List;
+import org.checkerframework.checker.nullness.compatqual.NullableType;
 
 /**
  * A track selection consisting of a static subset of selected tracks belonging to a {@link
@@ -35,6 +37,24 @@ import java.util.List;
  */
 public interface TrackSelection {
 
+  /** Contains of a subset of selected tracks belonging to a {@link TrackGroup}. */
+  final class Definition {
+    /** The {@link TrackGroup} which tracks belong to. */
+    public final TrackGroup group;
+    /** The indices of the selected tracks in {@link #group}. */
+    public final int[] tracks;
+
+    /**
+     * @param group The {@link TrackGroup}. Must not be null.
+     * @param tracks The indices of the selected tracks within the {@link TrackGroup}. Must not be
+     *     null or empty. May be in any order.
+     */
+    public Definition(TrackGroup group, int... tracks) {
+      this.group = group;
+      this.tracks = tracks;
+    }
+  }
+
   /**
    * Factory for {@link TrackSelection} instances.
    */
@@ -51,6 +71,33 @@ public interface TrackSelection {
      */
     TrackSelection createTrackSelection(
         TrackGroup group, BandwidthMeter bandwidthMeter, int... tracks);
+
+    /**
+     * Creates a new selection for each {@link Definition}.
+     *
+     * @param definitions A {@link Definition} array. May include null values.
+     * @param bandwidthMeter A {@link BandwidthMeter} which can be used to select tracks.
+     * @return The created selections. For null entries in {@code definitions} returns null values.
+     */
+    default @NullableType TrackSelection[] createTrackSelections(
+        @NullableType Definition[] definitions, BandwidthMeter bandwidthMeter) {
+      TrackSelection[] selections = new TrackSelection[definitions.length];
+      boolean createdAdaptiveTrackSelection = false;
+      for (int i = 0; i < definitions.length; i++) {
+        Definition definition = definitions[i];
+        if (definition == null) {
+          continue;
+        }
+        if (definition.tracks.length > 1) {
+          Assertions.checkState(!createdAdaptiveTrackSelection);
+          createdAdaptiveTrackSelection = true;
+          selections[i] = createTrackSelection(definition.group, bandwidthMeter, definition.tracks);
+        } else {
+          selections[i] = new FixedTrackSelection(definition.group, definition.tracks[0]);
+        }
+      }
+      return selections;
+    }
   }
 
   /**

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

@@ -773,7 +773,7 @@ public final class ExoPlayerTest {
     }
     // There are 2 renderers, and track selections are made twice. The second time one renderer is
     // disabled, so only one out of the two track selections is enabled.
-    assertThat(createdTrackSelections).hasSize(4);
+    assertThat(createdTrackSelections).hasSize(3);
     assertThat(numSelectionsEnabled).isEqualTo(3);
   }
 

playbacktests/src/androidTest/java/com/google/android/exoplayer2/playbacktests/gts/DashTestRunner.java

@@ -50,7 +50,6 @@ import com.google.android.exoplayer2.testutil.HostActivity;
 import com.google.android.exoplayer2.testutil.HostActivity.HostedTest;
 import com.google.android.exoplayer2.testutil.MetricsLogger;
 import com.google.android.exoplayer2.trackselection.DefaultTrackSelector;
-import com.google.android.exoplayer2.trackselection.FixedTrackSelection;
 import com.google.android.exoplayer2.trackselection.MappingTrackSelector;
 import com.google.android.exoplayer2.trackselection.RandomTrackSelection;
 import com.google.android.exoplayer2.trackselection.TrackSelection;
@@ -382,6 +381,7 @@ public final class DashTestRunner {
 
     private DashTestTrackSelector(String tag, String audioFormatId, String[] videoFormatIds,
         boolean canIncludeAdditionalVideoFormats) {
+      super(new RandomTrackSelection.Factory(/* seed= */ 0));
       this.tag = tag;
       this.audioFormatId = audioFormatId;
       this.videoFormatIds = videoFormatIds;
@@ -389,7 +389,7 @@ public final class DashTestRunner {
     }
 
     @Override
-    protected TrackSelection[] selectAllTracks(
+    protected TrackSelection.Definition[] selectAllTracks(
         MappedTrackInfo mappedTrackInfo,
         int[][][] rendererFormatSupports,
         int[] rendererMixedMimeTypeAdaptationSupports,
@@ -403,22 +403,22 @@ public final class DashTestRunner {
       TrackGroupArray audioTrackGroups = mappedTrackInfo.getTrackGroups(AUDIO_RENDERER_INDEX);
       Assertions.checkState(videoTrackGroups.length == 1);
       Assertions.checkState(audioTrackGroups.length == 1);
-      TrackSelection[] selections = new TrackSelection[mappedTrackInfo.getRendererCount()];
-      selections[VIDEO_RENDERER_INDEX] =
-          new RandomTrackSelection(
+      TrackSelection.Definition[] definitions =
+          new TrackSelection.Definition[mappedTrackInfo.getRendererCount()];
+      definitions[VIDEO_RENDERER_INDEX] =
+          new TrackSelection.Definition(
               videoTrackGroups.get(0),
               getVideoTrackIndices(
                   videoTrackGroups.get(0),
                   rendererFormatSupports[VIDEO_RENDERER_INDEX][0],
                   videoFormatIds,
-                  canIncludeAdditionalVideoFormats),
-              0 /* seed */);
-      selections[AUDIO_RENDERER_INDEX] =
-          new FixedTrackSelection(
+                  canIncludeAdditionalVideoFormats));
+      definitions[AUDIO_RENDERER_INDEX] =
+          new TrackSelection.Definition(
               audioTrackGroups.get(0), getTrackIndex(audioTrackGroups.get(0), audioFormatId));
       includedAdditionalVideoFormats =
-          selections[VIDEO_RENDERER_INDEX].length() > videoFormatIds.length;
-      return selections;
+          definitions[VIDEO_RENDERER_INDEX].tracks.length > videoFormatIds.length;
+      return definitions;
     }
 
     private int[] getVideoTrackIndices(

testutils_robolectric/src/main/java/com/google/android/exoplayer2/testutil/FakeTrackSelector.java

@@ -15,21 +15,19 @@
  */
 package com.google.android.exoplayer2.testutil;
 
-import android.support.annotation.NonNull;
-import com.google.android.exoplayer2.ExoPlaybackException;
 import com.google.android.exoplayer2.source.TrackGroup;
 import com.google.android.exoplayer2.source.TrackGroupArray;
 import com.google.android.exoplayer2.trackselection.DefaultTrackSelector;
 import com.google.android.exoplayer2.trackselection.MappingTrackSelector;
 import com.google.android.exoplayer2.trackselection.TrackSelection;
+import com.google.android.exoplayer2.upstream.BandwidthMeter;
 import java.util.ArrayList;
 import java.util.List;
 
 /** A fake {@link MappingTrackSelector} that returns {@link FakeTrackSelection}s. */
 public class FakeTrackSelector extends DefaultTrackSelector {
 
-  private final List<FakeTrackSelection> trackSelections = new ArrayList<>();
-  private final boolean mayReuseTrackSelection;
+  private final FakeTrackSelectionFactory fakeTrackSelectionFactory;
 
   public FakeTrackSelector() {
     this(false);
@@ -41,43 +39,71 @@ public class FakeTrackSelector extends DefaultTrackSelector {
    *     using the same {@link TrackGroup}.
    */
   public FakeTrackSelector(boolean mayReuseTrackSelection) {
-    this.mayReuseTrackSelection = mayReuseTrackSelection;
+    this(new FakeTrackSelectionFactory(mayReuseTrackSelection));
+  }
+
+  private FakeTrackSelector(FakeTrackSelectionFactory fakeTrackSelectionFactory) {
+    super(fakeTrackSelectionFactory);
+    this.fakeTrackSelectionFactory = fakeTrackSelectionFactory;
   }
 
   @Override
-  protected TrackSelection[] selectAllTracks(
+  protected TrackSelection.Definition[] selectAllTracks(
       MappedTrackInfo mappedTrackInfo,
       int[][][] rendererFormatSupports,
       int[] rendererMixedMimeTypeAdaptationSupports,
-      Parameters params)
-      throws ExoPlaybackException {
+      Parameters params) {
     int rendererCount = mappedTrackInfo.getRendererCount();
-    TrackSelection[] selections = new TrackSelection[rendererCount];
+    TrackSelection.Definition[] definitions = new TrackSelection.Definition[rendererCount];
     for (int i = 0; i < rendererCount; i++) {
       TrackGroupArray trackGroupArray = mappedTrackInfo.getTrackGroups(i);
       boolean hasTracks = trackGroupArray.length > 0;
-      selections[i] = hasTracks ? reuseOrCreateTrackSelection(trackGroupArray.get(0)) : null;
+      definitions[i] = hasTracks ? new TrackSelection.Definition(trackGroupArray.get(0)) : null;
     }
-    return selections;
+    return definitions;
   }
 
-  @NonNull
-  private FakeTrackSelection reuseOrCreateTrackSelection(TrackGroup trackGroup) {
-    if (mayReuseTrackSelection) {
-      for (FakeTrackSelection trackSelection : trackSelections) {
-        if (trackSelection.getTrackGroup().equals(trackGroup)) {
-          return trackSelection;
+  /** Returns list of all {@link FakeTrackSelection}s that this track selector has made so far. */
+  public List<FakeTrackSelection> getAllTrackSelections() {
+    return fakeTrackSelectionFactory.trackSelections;
+  }
+
+  private static class FakeTrackSelectionFactory implements TrackSelection.Factory {
+
+    private final List<FakeTrackSelection> trackSelections;
+    private final boolean mayReuseTrackSelection;
+
+    public FakeTrackSelectionFactory(boolean mayReuseTrackSelection) {
+      this.mayReuseTrackSelection = mayReuseTrackSelection;
+      trackSelections = new ArrayList<>();
+    }
+
+    @Override
+    public TrackSelection createTrackSelection(
+        TrackGroup trackGroup, BandwidthMeter bandwidthMeter, int... tracks) {
+      if (mayReuseTrackSelection) {
+        for (FakeTrackSelection trackSelection : trackSelections) {
+          if (trackSelection.getTrackGroup().equals(trackGroup)) {
+            return trackSelection;
+          }
         }
       }
+      FakeTrackSelection trackSelection = new FakeTrackSelection(trackGroup);
+      trackSelections.add(trackSelection);
+      return trackSelection;
     }
-    FakeTrackSelection trackSelection = new FakeTrackSelection(trackGroup);
-    trackSelections.add(trackSelection);
-    return trackSelection;
-  }
 
-  /** Returns list of all {@link FakeTrackSelection}s that this track selector has made so far. */
-  public List<FakeTrackSelection> getAllTrackSelections() {
-    return trackSelections;
+    @Override
+    public TrackSelection[] createTrackSelections(
+        TrackSelection.Definition[] definitions, BandwidthMeter bandwidthMeter) {
+      TrackSelection[] selections = new TrackSelection[definitions.length];
+      for (int i = 0; i < definitions.length; i++) {
+        TrackSelection.Definition definition = definitions[i];
+        if (definition != null) {
+          selections[i] = createTrackSelection(definition.group, bandwidthMeter, definition.tracks);
+        }
+      }
+      return selections;
+    }
   }
-
 }