encode static method

QRCode encode(String content, ErrorCorrectionLevel ecLevel, { EncodeHints? hints, })

@param content text to encode @param ecLevel error correction level to use @return {@link QRCode} representing the encoded QR code @throws WriterException if encoding can't succeed, because of for example invalid content or configuration

Implementation

static QRCode encode(String content, ErrorCorrectionLevel ecLevel,
    {EncodeHints? hints}) {
  hints ??= EncodeHints();
  // Determine what character encoding has been specified by the caller, if any
  var encoding = defaultByteModeEncoding;
  var hasEncodingHint = hints.contains(EncodeHintType.characterSet);
  if (hasEncodingHint) {
    encoding = hints.get(EncodeHintType.characterSet)!;
  }

  // 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. Twould be nice.
  var mode = chooseMode(content, encoding: encoding);

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

  // Append ECI segment if applicable
  if (mode == Mode.byte && hasEncodingHint) {
    var eci = encoding;
    _appendECI(eci, headerBits);
  }

  // Append the FNC1 mode header for GS1 formatted data if applicable
  if (hints.get(EncodeHintType.gs1Format) ?? false) {
    // 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.
  var dataBits = BitArray();
  appendBytes(content, mode, dataBits, encoding);

  Version version;
  var versionNumber = hints.get(EncodeHintType.qrVersion);
  if (versionNumber != null) {
    version = Version.getVersionForNumber(versionNumber);
    var 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);
  }

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

  var ecBlocks = version.getECBlocksForLevel(ecLevel);
  var numDataBytes = version.totalCodewords - ecBlocks.getTotalECCodewords();

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

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

  var qrCode = QRCode();

  qrCode.ecLevel = ecLevel;
  qrCode.mode = mode;
  qrCode.version = version;

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

  // Enable manual selection of the pattern to be used via hint
  var maskPattern = -1;
  if (hints.contains(EncodeHintType.qrMaskPattern)) {
    var hintMaskPattern = hints.get(EncodeHintType.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;
}