mergeAdvertisementData static method

Printer mergeAdvertisementData({ required Printer previous, required Printer incoming, })

Carry previous's advertisement data over to incoming when incoming has none of its own.

Records from getSystemDevices() or from a connection-state change carry no advertisement payload, so replacing a scanned record with one of them would drop the service UUIDs the scan already resolved.

The decision is all-or-nothing on purpose. A record that carries any advertisement data is treated as authoritative for all three fields, so a scan result whose serviceData is legitimately empty this time does not keep reporting bytes the peripheral has stopped advertising.

Named parameters rather than a receiver and an argument: the two are interchangeable at the call site and getting the order backwards would silently discard every fresh isConnected or name update.

Implementation

static Printer mergeAdvertisementData({
  required Printer previous,
  required Printer incoming,
}) {
  final hasOwnData = incoming.services.isNotEmpty ||
      incoming.serviceData.isNotEmpty ||
      incoming.manufacturerDataList.isNotEmpty;
  if (hasOwnData) {
    return incoming;
  }

  final hasInheritable = previous.services.isNotEmpty ||
      previous.serviceData.isNotEmpty ||
      previous.manufacturerDataList.isNotEmpty;
  if (!hasInheritable) {
    return incoming;
  }

  return incoming.copyWith(
    services: previous.services,
    serviceData: previous.serviceData,
    manufacturerDataList: previous.manufacturerDataList,
  );
}