How to use

updateCRC

method

in

com.mxgraph.util.png.CRC

public void writeToStream(DataOutputStream output) throws IOException
{
  byte[] typeSignature = new byte[4];
  typeSignature[0] = (byte) type.charAt(0);
  typeSignature[1] = (byte) type.charAt(1);
  typeSignature[2] = (byte) type.charAt(2);
  typeSignature[3] = (byte) type.charAt(3);
  dos.flush();
  baos.flush();
  byte[] data = baos.toByteArray();
  int len = data.length;
  output.writeInt(len);
  output.write(typeSignature);
  output.write(data, 0, len);
  int crc = 0xffffffff;
  crc = CRC.updateCRC(crc, typeSignature, 0, 4);
  crc = CRC.updateCRC(crc, data, 0, len);
  output.writeInt(crc ^ 0xffffffff);
}

public void writeToStream(DataOutputStream output) throws IOException
{
  byte[] typeSignature = new byte[4];
  typeSignature[0] = (byte) type.charAt(0);
  typeSignature[1] = (byte) type.charAt(1);
  typeSignature[2] = (byte) type.charAt(2);
  typeSignature[3] = (byte) type.charAt(3);
  dos.flush();
  baos.flush();
  byte[] data = baos.toByteArray();
  int len = data.length;
  output.writeInt(len);
  output.write(typeSignature);
  output.write(data, 0, len);
  int crc = 0xffffffff;
  crc = CRC.updateCRC(crc, typeSignature, 0, 4);
  crc = CRC.updateCRC(crc, data, 0, len);
  output.writeInt(crc ^ 0xffffffff);
}

public void flush() throws IOException
{
  // Length
  writeInt(bytesWritten);
  // 'IDAT' signature
  out.write(typeSignature);
  // Data
  out.write(buffer, 0, bytesWritten);
  int crc = 0xffffffff;
  crc = CRC.updateCRC(crc, typeSignature, 0, 4);
  crc = CRC.updateCRC(crc, buffer, 0, bytesWritten);
  // CRC
  writeInt(crc ^ 0xffffffff);
  // Reset buffer
  bytesWritten = 0;
}

public void flush() throws IOException
{
  // Length
  writeInt(bytesWritten);
  // 'IDAT' signature
  out.write(typeSignature);
  // Data
  out.write(buffer, 0, bytesWritten);
  int crc = 0xffffffff;
  crc = CRC.updateCRC(crc, typeSignature, 0, 4);
  crc = CRC.updateCRC(crc, buffer, 0, bytesWritten);
  // CRC
  writeInt(crc ^ 0xffffffff);
  // Reset buffer
  bytesWritten = 0;
}