writeBytes method

Future<PosPrintResult> writeBytes(List<int> bytes, { int chunkSizeBytes = 20, int queueSleepTimeMs = 20, })

Implementation

Future<PosPrintResult> writeBytes(
  List<int> bytes, {
  int chunkSizeBytes = 20,
  int queueSleepTimeMs = 20,
}) async {
  final Completer<PosPrintResult> completer = Completer();

  const int timeout = 5;
  if (_selectedPrinter == null) {
    return Future<PosPrintResult>.value(PosPrintResult.printerNotSelected);
  } else if (_isScanning.value!) {
    return Future<PosPrintResult>.value(PosPrintResult.scanInProgress);
  } else if (_isPrinting) {
    return Future<PosPrintResult>.value(PosPrintResult.printInProgress);
  }

  _isPrinting = true;

  // We have to rescan before connecting, otherwise we can connect only once
  await _bluetoothManager.startScan(timeout: Duration(seconds: 1));
  await _bluetoothManager.stopScan();

  // Connect
  await _bluetoothManager.connect(_selectedPrinter!._device);

  // Subscribe to the events
  _bluetoothManager.state.listen((state) async {
    switch (state) {
      case BluetoothManager.CONNECTED:
        // To avoid double call
        if (!_isConnected) {
          final len = bytes.length;
          List<List<int>> chunks = [];
          for (var i = 0; i < len; i += chunkSizeBytes) {
            var end = (i + chunkSizeBytes < len) ? i + chunkSizeBytes : len;
            chunks.add(bytes.sublist(i, end));
          }

          for (var i = 0; i < chunks.length; i += 1) {
            await _bluetoothManager.writeData(chunks[i]);
            sleep(Duration(milliseconds: queueSleepTimeMs));
          }

          completer.complete(PosPrintResult.success);
        }
        // TODO sending disconnect signal should be event-based
        _runDelayed(3).then((dynamic v) async {
          await _bluetoothManager.disconnect();
          _isPrinting = false;
        });
        _isConnected = true;
        break;
      case BluetoothManager.DISCONNECTED:
        _isConnected = false;
        break;
      default:
        break;
    }
  });

  // Printing timeout
  _runDelayed(timeout).then((dynamic v) async {
    if (_isPrinting) {
      _isPrinting = false;
      completer.complete(PosPrintResult.timeout);
    }
  });

  return completer.future;
}