+
−package ar.com.hjg.pngj.pixels;
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−
+
−import java.io.OutputStream;
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−
+
−import ar.com.hjg.pngj.IDatChunkWriter;
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−
+
−/**
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− * This is an OutputStream that compresses (via Deflater or a deflater-like object), and optionally passes the
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− * compressed stream to another output stream.
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− * 
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− * It allows to compute in/out/ratio stats.
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− * 
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− * It works as a stream (similar to DeflaterOutputStream), but it's peculiar in that it expects that each writes has a
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− * fixed length (other lenghts are accepted, but it's less efficient) and that the total amount of bytes is known (so it
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− * can close itself, but it can also be closed on demand) In PNGJ use, the block is typically a row (including filter
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− * byte).
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− * 
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− * We use this to do the real compression (with Deflate) but also to compute tentative estimators
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− * 
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− * If not closed, it can be recicled via reset()
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− * 
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− * 
+
− */
+
−public abstract class CompressorStream extends OutputStream {
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−
+
−  protected IDatChunkWriter idatChunkWriter;
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−  public final int blockLen;
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−  public final long totalbytes;
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−
+
−  boolean closed = false;
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−  protected boolean done = false;
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−  protected long bytesIn = 0;
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−  protected long bytesOut = 0;
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−  protected int block = -1;
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−
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−  /** optionally stores the first byte of each block (row) */
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−  private byte[] firstBytes;
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−  protected boolean storeFirstByte = false;
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−
+
−  /**
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−   * 
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−   * @param idatCw Can be null (if we are only interested in compute compression ratio)
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−   * @param blockLen Estimated maximum block length. If unknown, use -1.
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−   * @param totalbytes Expected total bytes to be fed. If unknown, use -1.
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−   */
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−  public CompressorStream(IDatChunkWriter idatCw, int blockLen, long totalbytes) {
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−    this.idatChunkWriter = idatCw;
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−    if (blockLen < 0)
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−      blockLen = 4096;
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−    if (totalbytes < 0)
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−      totalbytes = Long.MAX_VALUE;
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−    if (blockLen < 1 || totalbytes < 1)
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−      throw new RuntimeException(" maxBlockLen or totalLen invalid");
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−    this.blockLen = blockLen;
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−    this.totalbytes = totalbytes;
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−  }
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−
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−  /** Releases resources. Idempotent. */
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−  @Override
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−  public void close() {
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−    done();
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−    if(idatChunkWriter!=null) idatChunkWriter.close();
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−    closed = true;
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−  }
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−
+
−  /**
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−   * Will be called automatically when the number of bytes reaches the total expected Can be also be called from
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−   * outside. This should set the flag done=true
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−   */
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−  public abstract void done();
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−
+
−  @Override
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−  public final void write(byte[] data) {
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−    write(data, 0, data.length);
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−  }
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−
+
−  @Override
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−  public final void write(byte[] data, int off, int len) {
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−    block++;
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−    if (len <= blockLen) { // normal case
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−      mywrite(data, off, len);
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−      if (storeFirstByte && block < firstBytes.length) {
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−        firstBytes[block] = data[off]; // only makes sense in this case
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−      }
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−    } else {
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−      while (len > 0) {
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−        mywrite(data, off, blockLen);
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−        off += blockLen;
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−        len -= blockLen;
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−      }
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−    }
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−    if (bytesIn >= totalbytes)
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−      done();
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−
+
−  }
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−
+
−  /**
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−   * same as write, but guarantedd to not exceed blockLen The implementation should update bytesOut and bytesInt but not
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−   * check for totalBytes
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−   */
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−  public abstract void mywrite(byte[] data, int off, int len);
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−
+
−
+
−  /**
+
−   * compressed/raw. This should be called only when done
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−   */
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−  public final double getCompressionRatio() {
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−    return bytesOut == 0 ? 1.0 : bytesOut / (double) bytesIn;
+
−  }
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−
+
−  /**
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−   * raw (input) bytes. This should be called only when done
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−   */
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−  public final long getBytesRaw() {
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−    return bytesIn;
+
−  }
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−
+
−  /**
+
−   * compressed (out) bytes. This should be called only when done
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−   */
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−  public final long getBytesCompressed() {
+
−    return bytesOut;
+
−  }
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−
+
−  public boolean isClosed() {
+
−    return closed;
+
−  }
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−
+
−  public boolean isDone() {
+
−    return done;
+
−  }
+
−
+
−  public byte[] getFirstBytes() {
+
−    return firstBytes;
+
−  }
+
−
+
−  public void setStoreFirstByte(boolean storeFirstByte, int nblocks) {
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−    this.storeFirstByte = storeFirstByte;
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−    if (this.storeFirstByte) {
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−      if (firstBytes == null || firstBytes.length < nblocks)
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−        firstBytes = new byte[nblocks];
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−    } else
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−      firstBytes = null;
+
−  }
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−
+
−  public void reset() {
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−    done();
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−    bytesIn = 0;
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−    bytesOut = 0;
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−    block = -1;
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−    done = false;
+
−  }
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−
+
−  @Override
+
−  public void write(int i) { // should not be used
+
−    write(new byte[] {(byte) i});
+
−  }
+
−
+
−
+
−}