Java PooledByteBuffer.read方法代码示例

import com.facebook.common.memory.PooledByteBuffer; //导入方法依赖的package包/类
/**
 * Returns first n bytes of encoded image as hexbytes
 *
 * @param length the number of bytes to return
 */
public String getFirstBytesAsHexString(int length) {
  CloseableReference<PooledByteBuffer> imageBuffer = getByteBufferRef();
  if (imageBuffer == null) {
    return "";
  }
  int imageSize = getSize();
  int resultSampleSize = Math.min(imageSize, length);
  byte[] bytesBuffer = new byte[resultSampleSize];
  try {
    PooledByteBuffer pooledByteBuffer = imageBuffer.get();
    if (pooledByteBuffer == null) {
      return "";
    }
    pooledByteBuffer.read(0, bytesBuffer, 0, resultSampleSize);
  } finally {
    imageBuffer.close();
  }
  StringBuilder stringBuilder = new StringBuilder(bytesBuffer.length * 2);
  for (byte b : bytesBuffer) {
    stringBuilder.append(String.format("%02X", b));
  }
  return stringBuilder.toString();
}
 

import com.facebook.common.memory.PooledByteBuffer; //导入方法依赖的package包/类
/**
 * Decodes a byteArray into a purgeable bitmap
 *
 * @param bytesRef the byte buffer that contains the encoded bytes
 * @return
 */
@Override
protected Bitmap decodeByteArrayAsPurgeable(
    CloseableReference<PooledByteBuffer> bytesRef,
    BitmapFactory.Options options) {
  final PooledByteBuffer pooledByteBuffer = bytesRef.get();
  final int length = pooledByteBuffer.size();
  final CloseableReference<byte[]> encodedBytesArrayRef = mFlexByteArrayPool.get(length);
  try {
    final byte[] encodedBytesArray = encodedBytesArrayRef.get();
    pooledByteBuffer.read(0, encodedBytesArray, 0, length);
    Bitmap bitmap = BitmapFactory.decodeByteArray(
        encodedBytesArray,
        0,
        length,
        options);
    return Preconditions.checkNotNull(bitmap, "BitmapFactory returned null");
  } finally {
    CloseableReference.closeSafely(encodedBytesArrayRef);
  }
}
 

import com.facebook.common.memory.PooledByteBuffer; //导入方法依赖的package包/类
/**
 * Returns true if the image is a JPEG and its data is already complete at the specified length,
 * false otherwise.
 */
public boolean isCompleteAt(int length) {
  if (mImageFormat != DefaultImageFormats.JPEG) {
    return true;
  }
  // If the image is backed by FileInputStreams return true since they will always be complete.
  if (mInputStreamSupplier != null) {
    return true;
  }
  // The image should be backed by a ByteBuffer
  Preconditions.checkNotNull(mPooledByteBufferRef);
  PooledByteBuffer buf = mPooledByteBufferRef.get();
  return (buf.read(length - 2) == (byte) JfifUtil.MARKER_FIRST_BYTE)
      && (buf.read(length - 1) == (byte) JfifUtil.MARKER_EOI);
}
 

import com.facebook.common.memory.PooledByteBuffer; //导入方法依赖的package包/类
/**
 * Decodes a byteArray containing jpeg encoded bytes into a purgeable bitmap
 *
 * <p> Adds a JFIF End-Of-Image marker if needed before decoding.
 *
 * @param bytesRef the byte buffer that contains the encoded bytes
 * @return
 */
@Override
protected Bitmap decodeJPEGByteArrayAsPurgeable(
    CloseableReference<PooledByteBuffer> bytesRef,
    int length,
    BitmapFactory.Options options) {
  byte[] suffix = endsWithEOI(bytesRef, length) ? null : EOI;
  final PooledByteBuffer pooledByteBuffer = bytesRef.get();
  Preconditions.checkArgument(length <= pooledByteBuffer.size());
  // allocate bigger array in case EOI needs to be added
  final CloseableReference<byte[]> encodedBytesArrayRef = mFlexByteArrayPool.get(length + 2);
  try {
    byte[] encodedBytesArray = encodedBytesArrayRef.get();
    pooledByteBuffer.read(0, encodedBytesArray, 0, length);
    if (suffix != null) {
      putEOI(encodedBytesArray, length);
      length += 2;
    }
    Bitmap bitmap = BitmapFactory.decodeByteArray(
        encodedBytesArray,
        0,
        length,
        options);
    return Preconditions.checkNotNull(bitmap, "BitmapFactory returned null");
  } finally {
    CloseableReference.closeSafely(encodedBytesArrayRef);
  }
}
 

import com.facebook.common.memory.PooledByteBuffer; //导入方法依赖的package包/类
@TargetApi(Build.VERSION_CODES.HONEYCOMB_MR1)
@Override
public Bitmap createNakedBitmap(
    int width, int height, Bitmap.Config bitmapConfig) {
  CloseableReference<PooledByteBuffer> jpgRef = mJpegGenerator.generate(
      (short) width,
      (short) height);
  EncodedImage encodedImage = null;
  CloseableReference<byte[]> encodedBytesArrayRef = null;
  try {
    encodedImage = new EncodedImage(jpgRef);
    encodedImage.setImageFormat(DefaultImageFormats.JPEG);
    BitmapFactory.Options options = getBitmapFactoryOptions(
        encodedImage.getSampleSize(),
        bitmapConfig);
    int length = jpgRef.get().size();
    final PooledByteBuffer pooledByteBuffer = jpgRef.get();
    encodedBytesArrayRef =
        mFlexByteArrayPool.get(length + 2);
    byte[] encodedBytesArray = encodedBytesArrayRef.get();
    pooledByteBuffer.read(0, encodedBytesArray, 0, length);
    Bitmap bitmap = BitmapFactory.decodeByteArray(
        encodedBytesArray,
        0,
        length,
        options);
    bitmap.setHasAlpha(true);
    bitmap.eraseColor(Color.TRANSPARENT);
    return bitmap;
  } finally {
    CloseableReference.closeSafely(encodedBytesArrayRef);
    EncodedImage.closeSafely(encodedImage);
    CloseableReference.closeSafely(jpgRef);
  }
}
 

import com.facebook.common.memory.PooledByteBuffer; //导入方法依赖的package包/类
protected static boolean endsWithEOI(CloseableReference<PooledByteBuffer> bytesRef, int length) {
  PooledByteBuffer buffer = bytesRef.get();
  return length >= 2 &&
      buffer.read(length - 2) == (byte) JfifUtil.MARKER_FIRST_BYTE &&
      buffer.read(length - 1) == (byte) JfifUtil.MARKER_EOI;
}