Move inflate method to Util class

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=207857927

library/core/src/main/java/com/google/android/exoplayer2/text/pgs/PgsDecoder.java

@@ -25,7 +25,6 @@ import com.google.android.exoplayer2.util.Util;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
-import java.util.zip.DataFormatException;
 import java.util.zip.Inflater;
 
 /** A {@link SimpleSubtitleDecoder} for PGS subtitles. */
@@ -39,25 +38,22 @@ public final class PgsDecoder extends SimpleSubtitleDecoder {
   private static final byte INFLATE_HEADER = 0x78;
 
   private final ParsableByteArray buffer;
+  private final ParsableByteArray inflatedBuffer;
   private final CueBuilder cueBuilder;
 
   private Inflater inflater;
-  private byte[] inflatedData;
-  private int inflatedDataSize;
 
   public PgsDecoder() {
     super("PgsDecoder");
     buffer = new ParsableByteArray();
+    inflatedBuffer = new ParsableByteArray();
     cueBuilder = new CueBuilder();
   }
 
   @Override
   protected Subtitle decode(byte[] data, int size, boolean reset) throws SubtitleDecoderException {
-    if (maybeInflateData(data, size)) {
-      buffer.reset(inflatedData, inflatedDataSize);
-    } else {
-      buffer.reset(data, size);
-    }
+    buffer.reset(data, size);
+    maybeInflateData(buffer);
     cueBuilder.reset();
     ArrayList<Cue> cues = new ArrayList<>();
     while (buffer.bytesLeft() >= 3) {
@@ -69,31 +65,14 @@ public final class PgsDecoder extends SimpleSubtitleDecoder {
     return new PgsSubtitle(Collections.unmodifiableList(cues));
   }
 
-  private boolean maybeInflateData(byte[] data, int size) {
-    if (size == 0 || data[0] != INFLATE_HEADER) {
-      return false;
-    }
-    if (inflater == null) {
-      inflater = new Inflater();
-      inflatedData = new byte[size];
-    }
-    inflatedDataSize = 0;
-    inflater.setInput(data, 0, size);
-    try {
-      while (!inflater.finished() && !inflater.needsDictionary() && !inflater.needsInput()) {
-        if (inflatedDataSize == inflatedData.length) {
-          inflatedData = Arrays.copyOf(inflatedData, inflatedData.length * 2);
-        }
-        inflatedDataSize +=
-            inflater.inflate(
-                inflatedData, inflatedDataSize, inflatedData.length - inflatedDataSize);
+  private void maybeInflateData(ParsableByteArray buffer) {
+    if (buffer.bytesLeft() > 0 && buffer.peekUnsignedByte() == INFLATE_HEADER) {
+      if (inflater == null) {
+        inflater = new Inflater();
       }
-      return inflater.finished();
-    } catch (DataFormatException e) {
-      // Assume data is not compressed.
-      return false;
-    } finally {
-      inflater.reset();
+      if (Util.inflate(buffer, inflatedBuffer, inflater)) {
+        buffer.reset(inflatedBuffer.data, inflatedBuffer.limit());
+      } // else assume data is not compressed.
     }
   }
 

library/core/src/main/java/com/google/android/exoplayer2/util/Util.java

@@ -69,6 +69,8 @@ import java.util.concurrent.Executors;
 import java.util.concurrent.ThreadFactory;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
+import java.util.zip.DataFormatException;
+import java.util.zip.Inflater;
 import org.checkerframework.checker.initialization.qual.UnknownInitialization;
 import org.checkerframework.checker.nullness.qual.EnsuresNonNull;
 import org.checkerframework.checker.nullness.qual.PolyNull;
@@ -1639,6 +1641,53 @@ public final class Util {
     return toUpperInvariant(Locale.getDefault().getCountry());
   }
 
+  /**
+   * Uncompresses the data in {@code input}.
+   *
+   * @param input Wraps the compressed input data.
+   * @param output Wraps an output buffer to be used to store the uncompressed data. If {@code
+   *     output.data} is null or it isn't big enough to hold the uncompressed data, a new array is
+   *     created. If {@code true} is returned then the output's position will be set to 0 and its
+   *     length will be set to the length of the uncompressed data.
+   * @param inflater If not null, used to uncompressed the input. Otherwise a new {@link Inflater}
+   *     is created.
+   * @return Whether the input is uncompressed successfully.
+   */
+  public static boolean inflate(
+      ParsableByteArray input, ParsableByteArray output, @Nullable Inflater inflater) {
+    if (input.bytesLeft() <= 0) {
+      return false;
+    }
+    byte[] outputData = output.data;
+    if (outputData == null) {
+      outputData = new byte[input.bytesLeft()];
+    }
+    if (inflater == null) {
+      inflater = new Inflater();
+    }
+    inflater.setInput(input.data, input.getPosition(), input.bytesLeft());
+    try {
+      int outputSize = 0;
+      while (true) {
+        outputSize += inflater.inflate(outputData, outputSize, outputData.length - outputSize);
+        if (inflater.finished()) {
+          output.reset(outputData, outputSize);
+          return true;
+        }
+        if (inflater.needsDictionary() || inflater.needsInput()) {
+          return false;
+        }
+        if (outputSize == outputData.length) {
+          outputData = Arrays.copyOf(outputData, outputData.length * 2);
+        }
+      }
+    } catch (DataFormatException e) {
+      return false;
+    } finally {
+      inflater.reset();
+    }
+  }
+
   /**
    * Gets the physical size of the default display, in pixels.
    *

library/core/src/test/java/com/google/android/exoplayer2/util/UtilTest.java

@@ -27,8 +27,10 @@ import static com.google.common.truth.Truth.assertThat;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.testutil.TestUtil;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 import java.util.Random;
+import java.util.zip.Deflater;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.robolectric.RobolectricTestRunner;
@@ -247,6 +249,23 @@ public class UtilTest {
     }
   }
 
+  @Test
+  public void testInflate() {
+    byte[] testData = TestUtil.buildTestData(/*arbitrary test data size*/ 256 * 1024);
+    byte[] compressedData = new byte[testData.length * 2];
+    Deflater compresser = new Deflater(9);
+    compresser.setInput(testData);
+    compresser.finish();
+    int compressedDataLength = compresser.deflate(compressedData);
+    compresser.end();
+
+    ParsableByteArray input = new ParsableByteArray(compressedData, compressedDataLength);
+    ParsableByteArray output = new ParsableByteArray();
+    assertThat(Util.inflate(input, output, /* inflater= */ null)).isTrue();
+    assertThat(output.limit()).isEqualTo(testData.length);
+    assertThat(Arrays.copyOf(output.data, output.limit())).isEqualTo(testData);
+  }
+
   private static void assertEscapeUnescapeFileName(String fileName, String escapedFileName) {
     assertThat(escapeFileName(fileName)).isEqualTo(escapedFileName);
     assertThat(unescapeFileName(escapedFileName)).isEqualTo(fileName);