Example #1
0
  private DecoderResult decode(BitMatrixParser parser, Map<DecodeHintType, ?> hints)
      throws FormatException, ChecksumException {
    Version version = parser.readVersion();
    ErrorCorrectionLevel ecLevel = parser.readFormatInformation().getErrorCorrectionLevel();

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

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

    // Error-correct and copy data blocks together into a stream of bytes
    for (DataBlock dataBlock : dataBlocks) {
      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, version, ecLevel, hints);
  }
Example #2
0
  /**
   * Decodes a QR Code represented as a {@link BitMatrix}. A 1 or "true" is taken to mean a black
   * module.
   *
   * @param bits booleans representing white/black QR Code modules
   * @param hints decoding hints that should be used to influence decoding
   * @return text and bytes encoded within the QR Code
   * @throws FormatException if the QR Code cannot be decoded
   * @throws ChecksumException if error correction fails
   */
  public DecoderResult decode(BitMatrix bits, Map<DecodeHintType, ?> hints)
      throws FormatException, ChecksumException {

    // Construct a parser and read version, error-correction level
    BitMatrixParser parser = new BitMatrixParser(bits);
    FormatException fe = null;
    ChecksumException ce = null;
    try {
      return decode(parser, hints);
    } catch (FormatException e) {
      fe = e;
    } catch (ChecksumException e) {
      ce = e;
    }

    try {

      // Revert the bit matrix
      parser.remask();

      // Will be attempting a mirrored reading of the version and format info.
      parser.setMirror(true);

      // Preemptively read the version.
      parser.readVersion();

      // Preemptively read the format information.
      parser.readFormatInformation();

      /*
       * Since we're here, this means we have successfully detected some kind
       * of version and format information when mirrored. This is a good sign,
       * that the QR code may be mirrored, and we should try once more with a
       * mirrored content.
       */
      // Prepare for a mirrored reading.
      parser.mirror();

      DecoderResult result = decode(parser, hints);

      // Success! Notify the caller that the code was mirrored.
      result.setOther(new QRCodeDecoderMetaData(true));

      return result;

    } catch (FormatException | ChecksumException e) {
      // Throw the exception from the original reading
      if (fe != null) {
        throw fe;
      }
      if (ce != null) {
        throw ce;
      }
      throw e;
    }
  }