add method
Appends a copy of data and returns [offset, length] for the header.
Implementation
List<int> add(ByteData data) {
final offset = _bytes.length;
_bytes.add(
Uint8List.fromList(
data.buffer.asUint8List(data.offsetInBytes, data.lengthInBytes),
),
);
return <int>[offset, data.lengthInBytes];
}