Forwarding class for Renderer to support custom Metadata and Text Renderer

RELEASENOTES.md

@@ -17,6 +17,9 @@
         need to pass a value representing a specific duration from the default
         start position for which the corresponding media source has to be
         preloaded with this IntDef, instead of a position.
+    *   Add `ForwardingRenderer` implementation that forwards all method calls
+        to another renderer
+        ([1703](https://github.com/androidx/media/pull/1703)).
 *   Transformer:
 *   Track Selection:
 *   Extractors:

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/ForwardingRenderer.java

@@ -0,0 +1,208 @@
+/*
+ * Copyright 2024 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
+ *
+ *      https://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 androidx.media3.exoplayer;
+
+import androidx.annotation.Nullable;
+import androidx.media3.common.C;
+import androidx.media3.common.Format;
+import androidx.media3.common.Timeline;
+import androidx.media3.common.util.Clock;
+import androidx.media3.common.util.UnstableApi;
+import androidx.media3.exoplayer.analytics.PlayerId;
+import androidx.media3.exoplayer.source.MediaSource;
+import androidx.media3.exoplayer.source.SampleStream;
+import java.io.IOException;
+
+/** An overridable {@link Renderer} implementation forwarding all methods to another renderer. */
+@UnstableApi
+public class ForwardingRenderer implements Renderer {
+
+  private final Renderer renderer;
+
+  /** Creates a new instance that forwards all operations to {@code renderer}. */
+  public ForwardingRenderer(Renderer renderer) {
+    this.renderer = renderer;
+  }
+
+  @Override
+  public void handleMessage(@MessageType int messageType, @Nullable Object message)
+      throws ExoPlaybackException {
+    renderer.handleMessage(messageType, message);
+  }
+
+  @Override
+  public String getName() {
+    return renderer.getName();
+  }
+
+  @Override
+  public @C.TrackType int getTrackType() {
+    return renderer.getTrackType();
+  }
+
+  @Override
+  public RendererCapabilities getCapabilities() {
+    return renderer.getCapabilities();
+  }
+
+  @Override
+  public void init(int index, PlayerId playerId, Clock clock) {
+    renderer.init(index, playerId, clock);
+  }
+
+  @Nullable
+  @Override
+  public MediaClock getMediaClock() {
+    return renderer.getMediaClock();
+  }
+
+  @Override
+  public @State int getState() {
+    return renderer.getState();
+  }
+
+  @Override
+  public void enable(
+      RendererConfiguration configuration,
+      Format[] formats,
+      SampleStream stream,
+      long positionUs,
+      boolean joining,
+      boolean mayRenderStartOfStream,
+      long startPositionUs,
+      long offsetUs,
+      MediaSource.MediaPeriodId mediaPeriodId)
+      throws ExoPlaybackException {
+    renderer.enable(
+        configuration,
+        formats,
+        stream,
+        positionUs,
+        joining,
+        mayRenderStartOfStream,
+        startPositionUs,
+        offsetUs,
+        mediaPeriodId);
+  }
+
+  @Override
+  public void start() throws ExoPlaybackException {
+    renderer.start();
+  }
+
+  @Override
+  public void replaceStream(
+      Format[] formats,
+      SampleStream stream,
+      long startPositionUs,
+      long offsetUs,
+      MediaSource.MediaPeriodId mediaPeriodId)
+      throws ExoPlaybackException {
+    renderer.replaceStream(formats, stream, startPositionUs, offsetUs, mediaPeriodId);
+  }
+
+  @Nullable
+  @Override
+  public SampleStream getStream() {
+    return renderer.getStream();
+  }
+
+  @Override
+  public boolean hasReadStreamToEnd() {
+    return renderer.hasReadStreamToEnd();
+  }
+
+  @Override
+  public long getReadingPositionUs() {
+    return renderer.getReadingPositionUs();
+  }
+
+  @Override
+  public long getDurationToProgressUs(long positionUs, long elapsedRealtimeUs) {
+    return renderer.getDurationToProgressUs(positionUs, elapsedRealtimeUs);
+  }
+
+  @Override
+  public void setCurrentStreamFinal() {
+    renderer.setCurrentStreamFinal();
+  }
+
+  @Override
+  public boolean isCurrentStreamFinal() {
+    return renderer.isCurrentStreamFinal();
+  }
+
+  @Override
+  public void maybeThrowStreamError() throws IOException {
+    renderer.maybeThrowStreamError();
+  }
+
+  @Override
+  public void resetPosition(long positionUs) throws ExoPlaybackException {
+    renderer.resetPosition(positionUs);
+  }
+
+  @Override
+  public void setPlaybackSpeed(float currentPlaybackSpeed, float targetPlaybackSpeed)
+      throws ExoPlaybackException {
+    renderer.setPlaybackSpeed(currentPlaybackSpeed, targetPlaybackSpeed);
+  }
+
+  @Override
+  public void enableMayRenderStartOfStream() {
+    renderer.enableMayRenderStartOfStream();
+  }
+
+  @Override
+  public void setTimeline(Timeline timeline) {
+    renderer.setTimeline(timeline);
+  }
+
+  @Override
+  public void render(long positionUs, long elapsedRealtimeUs) throws ExoPlaybackException {
+    renderer.render(positionUs, elapsedRealtimeUs);
+  }
+
+  @Override
+  public boolean isReady() {
+    return renderer.isReady();
+  }
+
+  @Override
+  public boolean isEnded() {
+    return renderer.isEnded();
+  }
+
+  @Override
+  public void stop() {
+    renderer.stop();
+  }
+
+  @Override
+  public void disable() {
+    renderer.disable();
+  }
+
+  @Override
+  public void reset() {
+    renderer.reset();
+  }
+
+  @Override
+  public void release() {
+    renderer.release();
+  }
+}

libraries/exoplayer/src/test/java/androidx/media3/exoplayer/ForwardingRendererTest.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2024 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
+ *
+ *      https://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 androidx.media3.exoplayer;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import androidx.media3.test.utils.TestUtil;
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+import java.lang.reflect.Method;
+import java.util.List;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+/** Unit tests for {@link ForwardingRenderer}. */
+@RunWith(AndroidJUnit4.class)
+public class ForwardingRendererTest {
+  @Test
+  public void forwardingRenderer_overridesAllMethods() throws NoSuchMethodException {
+    // Check with reflection that ForwardingRenderer overrides all Renderer methods.
+    List<Method> methods = TestUtil.getPublicMethods(Renderer.class);
+    for (Method method : methods) {
+      assertThat(
+              ForwardingRenderer.class
+                  .getDeclaredMethod(method.getName(), method.getParameterTypes())
+                  .getDeclaringClass())
+          .isEqualTo(ForwardingRenderer.class);
+    }
+  }
+}