From 72f26d79f6f74e20f346fd400de4c4babe59ca5c Mon Sep 17 00:00:00 2001
From: Colin Kho <colinkho@meta.com>
Date: Thu, 5 Sep 2024 22:51:49 -0700
Subject: [PATCH] Added a forwarding class for Renderer to support composing
 custom behavior on Metadata & Text Renderers

---
 .../media3/exoplayer/ForwardingRenderer.java  | 156 ++++++++++++++++++
 .../audio/ForwardingRendererTest.java         |  27 +++
 2 files changed, 183 insertions(+)
 create mode 100644 libraries/exoplayer/src/main/java/androidx/media3/exoplayer/ForwardingRenderer.java
 create mode 100644 libraries/exoplayer/src/test/java/androidx/media3/exoplayer/audio/ForwardingRendererTest.java

diff --git a/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/ForwardingRenderer.java b/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/ForwardingRenderer.java
new file mode 100644
index 0000000000..8996384c43
--- /dev/null
+++ b/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/ForwardingRenderer.java
@@ -0,0 +1,156 @@
+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.exoplayer.analytics.PlayerId;
+import androidx.media3.exoplayer.source.MediaSource;
+import androidx.media3.exoplayer.source.SampleStream;
+import java.io.IOException;
+
+/** An overridable {@link ForwardingRenderer} implementation forwarding all methods to another renderer. */
+public class ForwardingRenderer implements Renderer {
+
+  private final Renderer 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
+  @C.TrackType
+  public 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 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 setTimeline(Timeline 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();
+  }
+}
diff --git a/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/audio/ForwardingRendererTest.java b/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/audio/ForwardingRendererTest.java
new file mode 100644
index 0000000000..ed65e25137
--- /dev/null
+++ b/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/audio/ForwardingRendererTest.java
@@ -0,0 +1,27 @@
+package androidx.media3.exoplayer.audio;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import androidx.media3.exoplayer.ForwardingRenderer;
+import androidx.media3.exoplayer.Renderer;
+import androidx.media3.test.utils.TestUtil;
+import java.lang.reflect.Method;
+import java.util.List;
+import org.junit.Test;
+
+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) {
+      if (!method.isDefault()) {
+        assertThat(
+            ForwardingRenderer.class
+                .getDeclaredMethod(method.getName(), method.getParameterTypes())
+                .getDeclaringClass())
+            .isEqualTo(ForwardingRenderer.class);
+      }
+    }
+  }
+}