Create SingleSampleSeekMap and use in pngExtractor

PiperOrigin-RevId: 553191571

libraries/extractor/src/main/java/androidx/media3/extractor/SingleSampleSeekMap.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2023 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
+ *
+ *      http://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.extractor;
+
+import androidx.media3.common.C;
+import androidx.media3.common.util.UnstableApi;
+
+/**
+ * A {@link SeekMap} implementation that maps the given point back onto itself.
+ *
+ * <p>Used for single sample media.
+ */
+@UnstableApi
+public final class SingleSampleSeekMap implements SeekMap {
+  private final long durationUs;
+  private final long startPosition;
+
+  /**
+   * Creates an instance with {@code startPosition} set to 0.
+   *
+   * @param durationUs The duration of the stream in microseconds, or {@link C#TIME_UNSET} if the
+   *     duration is unknown.
+   */
+  public SingleSampleSeekMap(long durationUs) {
+    this(durationUs, /* startPosition= */ 0);
+  }
+
+  /**
+   * Creates an instance.
+   *
+   * @param durationUs The duration of the stream in microseconds, or {@link C#TIME_UNSET} if the
+   *     duration is unknown.
+   * @param startPosition The position (byte offset) of the start of the media.
+   */
+  public SingleSampleSeekMap(long durationUs, long startPosition) {
+    this.durationUs = durationUs;
+    this.startPosition = startPosition;
+  }
+
+  @Override
+  public boolean isSeekable() {
+    return true;
+  }
+
+  @Override
+  public long getDurationUs() {
+    return durationUs;
+  }
+
+  @Override
+  public SeekPoints getSeekPoints(long timeUs) {
+    return new SeekPoints(new SeekPoint(timeUs, startPosition));
+  }
+}

libraries/extractor/src/main/java/androidx/media3/extractor/png/PngExtractor.java

@@ -29,7 +29,7 @@ import androidx.media3.extractor.Extractor;
 import androidx.media3.extractor.ExtractorInput;
 import androidx.media3.extractor.ExtractorOutput;
 import androidx.media3.extractor.PositionHolder;
-import androidx.media3.extractor.SeekMap;
+import androidx.media3.extractor.SingleSampleSeekMap;
 import androidx.media3.extractor.TrackOutput;
 import java.io.IOException;
 import java.lang.annotation.Documented;
@@ -42,7 +42,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 @UnstableApi
 // TODO: b/289989902 - Move methods of this class into ImageExtractorUtil once there are multiple
 //   image extractors.
-public class PngExtractor implements Extractor {
+public final class PngExtractor implements Extractor {
 
   /** Parser states. */
   @Documented
@@ -110,7 +110,7 @@ public class PngExtractor implements Extractor {
     TrackOutput imageTrackOutput = extractorOutput.track(IMAGE_TRACK_ID, C.TRACK_TYPE_IMAGE);
     imageTrackOutput.format(new Format.Builder().setContainerMimeType(MimeTypes.IMAGE_PNG).build());
     extractorOutput.endTracks();
-    extractorOutput.seekMap(new SeekMap.Unseekable(/* durationUs= */ C.TIME_UNSET));
+    extractorOutput.seekMap(new SingleSampleSeekMap(/* durationUs= */ C.TIME_UNSET));
     state = STATE_READING_IMAGE;
   }
 

libraries/test_data/src/test/assets/extractordumps/png/non-motion-photo-shortened.png.0.dump

@@ -1,7 +1,8 @@
 seekMap:
-  isSeekable = false
+  isSeekable = true
   duration = UNSET TIME
   getPosition(0) = [[timeUs=0, position=0]]
+  getPosition(1) = [[timeUs=1, position=0]]
 numberOfTracks = 1
 track 1024:
   total output bytes = 29063

libraries/test_data/src/test/assets/extractordumps/png/non-motion-photo-shortened.png.unknown_length.dump

@@ -1,7 +1,8 @@
 seekMap:
-  isSeekable = false
+  isSeekable = true
   duration = UNSET TIME
   getPosition(0) = [[timeUs=0, position=0]]
+  getPosition(1) = [[timeUs=1, position=0]]
 numberOfTracks = 1
 track 1024:
   total output bytes = 29063