writeHeader method

Future<void> writeHeader(FileWriter out)

Write the header data to the DBF file.

@param out A channel to write to. If you have an OutputStream you can obtain the correct channel by using java.nio.Channels.newChannel(OutputStream out). @ If errors occur.

Implementation

Future<void> writeHeader(FileWriter out) async {
  // take care of the annoying case where no records have been added...
  if (headerLength == -1) {
    headerLength = MINIMUM_HEADER;
  }

  Endian endian = Endian.little;
  List<int> buffer = []; //List(headerLength);
  // write the output file type.
  buffer.add(MAGIC);

  // write the date stuff
  DateTime dt = DateTime.now();
  // // Calendar c = Calendar.getInstance();
  // c.setTime(Date());
  buffer.add(dt.year % 100); //        (byte) (c.get(Calendar.YEAR) % 100));
  buffer.add(dt.month); //   (byte) (c.get(Calendar.MONTH) + 1));
  buffer.add(dt.day); // (byte) (c.get(Calendar.DAY_OF_MONTH)));

  // write the number of records in the datafile.
  // buffer.putInt(recordCnt);
  buffer.addAll(
      ByteConversionUtilities.bytesFromInt32(recordCnt, endian: endian));

  // write the length of the header structure.
  // buffer.putShort((short) headerLength);
  buffer.addAll(
      ByteConversionUtilities.bytesFromInt16(headerLength, endian: endian));

  // write the length of a record
  // buffer.putShort((short) recordLength);
  buffer.addAll(
      ByteConversionUtilities.bytesFromInt16(recordLength, endian: endian));

  // // write the reserved bytes in the header
  // for (int i=0; i<20; i++) out.writeByteLE(0);
  // buffer.position(buffer.position() + 20);
  for (var i = 0; i < 20; i++) {
    buffer.add(0);
  }

  // write all of the header records
  int tempOffset = 0;
  for (int i = 0; i < fields.length; i++) {
    // write the field name
    var fn = fields[i].fieldName;
    // if (fn.length < 11) {
    //   buffer.addAll(fn.codeUnits); // TODO CHARSET?
    // } else {
    //   buffer.addAll(fn.substring(0, 11).codeUnits);
    // }

    for (int j = 0; j < 11; j++) {
      if (fn.length > j) {
        buffer.add(fn.codeUnitAt(j));
      } else {
        buffer.add(0);
      }
    }

    // write the field type
    buffer.add(fields[i].fieldType);
    // // write the field data address, offset from the start of the
    // record.
    buffer.addAll(ByteConversionUtilities.bytesFromInt32(tempOffset));
    tempOffset += fields[i].fieldLength;

    // write the length of the field.
    buffer.add(fields[i].fieldLength);

    // write the decimal count.
    buffer.add(fields[i].decimalCount);

    // write the reserved bytes.
    // for (in j=0; jj<14; j++) out.writeByteLE(0);
    // buffer.position(buffer.position() + 14);
    for (var i = 0; i < 14; i++) {
      buffer.add(0);
    }
  }

  // write the end of the field definitions marker
  buffer.add(0x0D);

  await out.put(buffer);
}