private void AdvertisementWatcherReceivedHandler(BluetoothLEAdvertisementWatcher sender, BluetoothLEAdvertisementReceivedEventArgs args)
{
foreach (var manufacturerData in args.Advertisement.ManufacturerData)
{
const int appleCompanyId = 0x4c;
if (manufacturerData.CompanyId != appleCompanyId)
{
continue;
}
BeaconAdvertisement advertisement;
using (var dataReader = DataReader.FromBuffer(manufacturerData.Data))
{
var subtype = dataReader.ReadByte();
if (subtype != 2)
{
return;
}
var subtypeLength = dataReader.ReadByte();
if (subtypeLength != 0x15)
{
return;
}
var a = dataReader.ReadInt32();
var b = dataReader.ReadInt16();
var c = dataReader.ReadInt16();
var d = new byte[8];
dataReader.ReadBytes(d);
var uuid = new Guid(a, b, c, d);
var major = dataReader.ReadUInt16();
var minor = dataReader.ReadUInt16();
var txPower = (sbyte)dataReader.ReadByte();
advertisement = new BeaconAdvertisement(
beaconData: new BeaconData(
uuid: uuid,
major: major,
minor: minor),
txPower: txPower,
rssi: args.RawSignalStrengthInDBm,
timestamp: args.Timestamp);
}
lock (_syncRoot)
{
_advertisements.Add(advertisement);
}
}
}
private void ExpirationTimerElapsedHandler(ThreadPoolTimer timer)
{
lock (_syncRoot)
{
_advertisements.RemoveAll(x => DateTimeOffset.Now - x.Timestamp > _expirationPeriod);
if (_advertisements.Count == 0)
{
NearestBeacon = null;
}
else
{
NearestBeacon = _advertisements.MaxBy(x => x.Rssi);
}
}
}
private void OnNearestBeaconChanged(BeaconAdvertisement e)
{
NearestBeaconChanged?.Invoke(this, e);
}