encode static method

QRCode encode(String content, [ ErrorCorrectionLevel ecLevel = ErrorCorrectionLevel.H, EncodeHint? hints ])

Implementation

static QRCode encode(
  String content, [
  ErrorCorrectionLevel ecLevel = ErrorCorrectionLevel.H,
  EncodeHint? hints,
]) {
  Version version;
  BitArray headerAndDataBits;
  Mode mode;

  final hasGS1FormatHint = hints?.gs1Format ?? false;

  final hasCompactionHint = hints?.qrCompact ?? false;

  // Determine what character encoding has been specified by the caller, if any
  Encoding? encoding = defaultByteModeEncoding;
  final hasEncodingHint = hints?.characterSet != null;
  if (hasEncodingHint) {
    encoding = CharacterSetECI.getCharacterSetECIByName(
      hints!.characterSet!,
    )?.charset;
  }

  if (hasCompactionHint) {
    mode = Mode.byte;

    final priorityEncoding =
        encoding == defaultByteModeEncoding ? null : encoding;
    final rn = MinimalEncoder.encode(
      content,
      null,
      priorityEncoding,
      hasGS1FormatHint,
      ecLevel,
    );

    headerAndDataBits = BitArray();
    rn.getBits(headerAndDataBits);
    version = rn.getVersion();
  } else {
    // Pick an encoding mode appropriate for the content. Note that this will not attempt to use
    // multiple modes / segments even if that were more efficient.
    mode = _chooseMode(content, encoding);

    // This will store the header information, like mode and
    // length, as well as "header" segments like an ECI segment.
    final headerBits = BitArray();

    // Append ECI segment if applicable
    if (mode == Mode.byte && hasEncodingHint && encoding != null) {
      final eci = CharacterSetECI.getCharacterSetECI(encoding);
      if (eci != null) {
        _appendECI(eci, headerBits);
      }
    }

    // Append the FNC1 mode header for GS1 formatted data if applicable
    if (hasGS1FormatHint) {
      // GS1 formatted codes are prefixed with a FNC1 in first position mode header
      appendModeInfo(Mode.fnc1FirstPosition, headerBits);
    }

    // (With ECI in place,) Write the mode marker
    appendModeInfo(mode, headerBits);

    // Collect data within the main segment, separately, to count its size if needed. Don't add it to
    // main payload yet.
    final dataBits = BitArray();
    appendBytes(content, mode, dataBits, encoding!);

    if (hints?.qrVersion != null) {
      final versionNumber = hints!.qrVersion!;
      version = Version.getVersionForNumber(versionNumber);
      final bitsNeeded = _calculateBitsNeeded(
        mode,
        headerBits,
        dataBits,
        version,
      );
      if (!willFit(bitsNeeded, version, ecLevel)) {
        throw WriterException('Data too big for requested version');
      }
    } else {
      version = _recommendVersion(ecLevel, mode, headerBits, dataBits);
    }

    headerAndDataBits = BitArray();
    headerAndDataBits.appendBitArray(headerBits);
    // Find "length" of main segment and write it
    final numLetters =
        mode == Mode.byte ? dataBits.sizeInBytes : content.length;
    appendLengthInfo(numLetters, version, mode, headerAndDataBits);
    // Put data together into the overall payload
    headerAndDataBits.appendBitArray(dataBits);
  }

  final ecBlocks = version.getECBlocksForLevel(ecLevel);
  final numDataBytes = version.totalCodewords - ecBlocks.totalECCodewords;

  // Terminate the bits properly.
  terminateBits(numDataBytes, headerAndDataBits);

  // Interleave data bits with error correction code.
  final finalBits = interleaveWithECBytes(
    headerAndDataBits,
    version.totalCodewords,
    numDataBytes,
    ecBlocks.numBlocks,
  );

  final qrCode = QRCode(ecLevel: ecLevel, mode: mode, version: version);

  //  Choose the mask pattern and set to "qrCode".
  final dimension = version.dimensionForVersion;
  final matrix = ByteMatrix(dimension, dimension);

  // Enable manual selection of the pattern to be used via hint
  int maskPattern = -1;
  if (hints?.qrMaskPattern != null) {
    final hintMaskPattern = hints!.qrMaskPattern!;
    maskPattern =
        QRCode.isValidMaskPattern(hintMaskPattern) ? hintMaskPattern : -1;
  }

  if (maskPattern == -1) {
    maskPattern = _chooseMaskPattern(finalBits, ecLevel, version, matrix);
  }
  qrCode.maskPattern = maskPattern;

  // Build the matrix and set it to "qrCode".
  MatrixUtil.buildMatrix(finalBits, ecLevel, version, maskPattern, matrix);
  qrCode.matrix = matrix;

  return qrCode;
}