addFile method
Implementation
Future<void> addFile(File file, [String? filename, int? level]) async {
final fileStream = InputFileStream(file.path);
filename ??= path.basename(file.path);
filename = path.posix.fromUri(path.toUri(filename));
final archiveFile = ArchiveFile.stream(filename, fileStream);
archiveFile.lastModTime =
(await file.lastModified()).millisecondsSinceEpoch ~/ 1000;
archiveFile.mode = (await file.stat()).mode;
_encoder.add(archiveFile, level: level);
await fileStream.close();
}