Add getReadingPositionUs to Renderer.

This method is a generalization of the existing hasReadStreamToEnd. It is
useful to determine whether a renderer already read beyond a new duration of
a period.

PiperOrigin-RevId: 230689165

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

@@ -37,7 +37,7 @@ public abstract class BaseRenderer implements Renderer, RendererCapabilities {
   private SampleStream stream;
   private Format[] streamFormats;
   private long streamOffsetUs;
-  private boolean readEndOfStream;
+  private long readingPositionUs;
   private boolean streamIsFinal;
 
   /**
@@ -46,7 +46,7 @@ public abstract class BaseRenderer implements Renderer, RendererCapabilities {
    */
   public BaseRenderer(int trackType) {
     this.trackType = trackType;
-    readEndOfStream = true;
+    readingPositionUs = C.TIME_END_OF_SOURCE;
   }
 
   @Override
@@ -98,7 +98,7 @@ public abstract class BaseRenderer implements Renderer, RendererCapabilities {
       throws ExoPlaybackException {
     Assertions.checkState(!streamIsFinal);
     this.stream = stream;
-    readEndOfStream = false;
+    readingPositionUs = offsetUs;
     streamFormats = formats;
     streamOffsetUs = offsetUs;
     onStreamChanged(formats, offsetUs);
@@ -111,7 +111,12 @@ public abstract class BaseRenderer implements Renderer, RendererCapabilities {
 
   @Override
   public final boolean hasReadStreamToEnd() {
-    return readEndOfStream;
+    return readingPositionUs == C.TIME_END_OF_SOURCE;
+  }
+
+  @Override
+  public final long getReadingPositionUs() {
+    return readingPositionUs;
   }
 
   @Override
@@ -132,7 +137,7 @@ public abstract class BaseRenderer implements Renderer, RendererCapabilities {
   @Override
   public final void resetPosition(long positionUs) throws ExoPlaybackException {
     streamIsFinal = false;
-    readEndOfStream = false;
+    readingPositionUs = positionUs;
     onPositionReset(positionUs, false);
   }
 
@@ -303,10 +308,11 @@ public abstract class BaseRenderer implements Renderer, RendererCapabilities {
     int result = stream.readData(formatHolder, buffer, formatRequired);
     if (result == C.RESULT_BUFFER_READ) {
       if (buffer.isEndOfStream()) {
-        readEndOfStream = true;
+        readingPositionUs = C.TIME_END_OF_SOURCE;
         return streamIsFinal ? C.RESULT_BUFFER_READ : C.RESULT_NOTHING_READ;
       }
       buffer.timeUs += streamOffsetUs;
+      readingPositionUs = Math.max(readingPositionUs, buffer.timeUs);
     } else if (result == C.RESULT_FORMAT_READ) {
       Format format = formatHolder.format;
       if (format.subsampleOffsetUs != Format.OFFSET_SAMPLE_RELATIVE) {
@@ -332,7 +338,7 @@ public abstract class BaseRenderer implements Renderer, RendererCapabilities {
    * Returns whether the upstream source is ready.
    */
   protected final boolean isSourceReady() {
-    return readEndOfStream ? streamIsFinal : stream.isReady();
+    return hasReadStreamToEnd() ? streamIsFinal : stream.isReady();
   }
 
   /**

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

@@ -123,6 +123,11 @@ public abstract class NoSampleRenderer implements Renderer, RendererCapabilities
   }
 
   @Override
+  public long getReadingPositionUs() {
+    return C.TIME_END_OF_SOURCE;
+  }
+
+  @Override
   public final void setCurrentStreamFinal() {
     streamIsFinal = true;
   }

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

@@ -161,6 +161,16 @@ public interface Renderer extends PlayerMessage.Target {
   boolean hasReadStreamToEnd();
 
   /**
+   * Returns the playback position up to which the renderer has read samples from the current {@link
+   * SampleStream}, in microseconds, or {@link C#TIME_END_OF_SOURCE} if the renderer has read the
+   * current {@link SampleStream} to the end.
+   *
+   * <p>This method may be called when the renderer is in the following states: {@link
+   * #STATE_ENABLED}, {@link #STATE_STARTED}.
+   */
+  long getReadingPositionUs();
+
+  /**
    * Signals to the renderer that the current {@link SampleStream} will be the final one supplied
    * before it is next disabled or reset.
    * <p>