Example #1
0
  /**
   * Decodes a Data Matrix Code represented as a {@link BitMatrix}. A 1 or "true" is taken to mean a
   * black module.
   *
   * @param bits booleans representing white/black Data Matrix Code modules
   * @return text and bytes encoded within the Data Matrix Code
   * @throws FormatException if the Data Matrix Code cannot be decoded
   * @throws ChecksumException if error correction fails
   */
  public DecoderResult decode(BitMatrix bits) throws FormatException, ChecksumException {

    // Construct a parser and read version, error-correction level
    BitMatrixParser parser = new BitMatrixParser(bits);
    Version version = parser.getVersion();

    // Read codewords
    byte[] codewords = parser.readCodewords();
    // Separate into data blocks
    DataBlock[] dataBlocks = DataBlock.getDataBlocks(codewords, version);

    // Count total number of data bytes
    int totalBytes = 0;
    for (int i = 0; i < dataBlocks.length; i++) {
      totalBytes += dataBlocks[i].getNumDataCodewords();
    }
    byte[] resultBytes = new byte[totalBytes];
    int resultOffset = 0;

    // Error-correct and copy data blocks together into a stream of bytes
    for (int j = 0; j < dataBlocks.length; j++) {
      DataBlock dataBlock = dataBlocks[j];
      byte[] codewordBytes = dataBlock.getCodewords();
      int numDataCodewords = dataBlock.getNumDataCodewords();
      correctErrors(codewordBytes, numDataCodewords);
      for (int i = 0; i < numDataCodewords; i++) {
        resultBytes[resultOffset++] = codewordBytes[i];
      }
    }

    // Decode the contents of that stream of bytes
    return DecodedBitStreamParser.decode(resultBytes);
  }