decodeAsText static method

Implementation

static String decodeAsText(
  final Uint8List data,
  final String? transferEncoding,
  final String? charset,
) {
  if (transferEncoding == null && charset == null) {
    // this could be a) UTF-8 or b) UTF-16 most likely:
    final utf8Decoded = encodingUtf8.decode(data, allowMalformed: true);
    if (utf8Decoded.contains('�')) {
      final comparison = String.fromCharCodes(data);
      if (!comparison.contains('�')) {
        return comparison;
      }
    }

    return utf8Decoded;
  }
  // there is actually just one interesting case:
  // when the transfer encoding is 8bit, the text needs to be decoded with
  // the specified charset.
  // Note that some mail senders also declare 7bit message encoding even when
  // UTF8 or other 8bit encodings are used.
  // In other cases the text is ASCII and the 'normal' decodeAnyText method
  // can be used.
  final transferEncodingLC = transferEncoding?.toLowerCase() ?? '8bit';
  if (transferEncodingLC == '8bit' ||
      transferEncodingLC == '7bit' ||
      transferEncodingLC == 'binary') {
    final cs = charset ?? 'utf8';
    final codec = _charsetCodecsByName[cs.toLowerCase()]?.call();
    if (codec == null) {
      print('Error: no encoding found for charset [$cs].');

      return encodingUtf8.decode(data, allowMalformed: true);
    }
    final decodedText = codec.decode(data);

    return decodedText;
  }
  final text = String.fromCharCodes(data);

  return decodeAnyText(text, transferEncoding, charset);
}