protected override async Task InitializeAsync()
{
await base.InitializeAsync();
// BLE requires location permissions
if (await SensusServiceHelper.Get().ObtainPermissionAsync(Permission.Location) != PermissionStatus.Granted)
{
// throw standard exception instead of NotSupportedException, since the user might decide to enable location in the future
// and we'd like the probe to be restarted at that time.
string error = "Geolocation is not permitted on this device. Cannot start Bluetooth probe.";
await SensusServiceHelper.Get().FlashNotificationAsync(error);
throw new Exception(error);
}
_deviceIdCharacteristic = new BluetoothGattCharacteristic(UUID.FromString(DEVICE_ID_CHARACTERISTIC_UUID), GattProperty.Read, GattPermission.Read);
_deviceIdCharacteristic.SetValue(Encoding.UTF8.GetBytes(SensusServiceHelper.Get().DeviceId));
_deviceIdService = new BluetoothGattService(UUID.FromString(Protocol.Id), GattServiceType.Primary);
_deviceIdService.AddCharacteristic(_deviceIdCharacteristic);
_bluetoothAdvertiserCallback = new AndroidBluetoothServerAdvertisingCallback(_deviceIdService, _deviceIdCharacteristic);
if (ScanMode.HasFlag(BluetoothScanModes.Classic))
{
_bluetoothBroadcastReceiver = new AndroidBluetoothDeviceReceiver(this);
IntentFilter intentFilter = new IntentFilter();
intentFilter.AddAction(BluetoothDevice.ActionFound);
Application.Context.RegisterReceiver(_bluetoothBroadcastReceiver, intentFilter);
}
}
protected override async Task ScanAsync(CancellationToken cancellationToken)
{
// start a scan if bluetooth is present and enabled
if (BluetoothAdapter.DefaultAdapter?.IsEnabled ?? false)
{
try
{
if (ScanMode.HasFlag(BluetoothScanModes.LE))
{
List <ScanFilter> scanFilters = new List <ScanFilter>();
if (DiscoverAll == false)
{
ScanFilter scanFilter = new ScanFilter.Builder()
.SetServiceUuid(new ParcelUuid(_deviceIdService.Uuid))
.Build();
scanFilters.Add(scanFilter);
}
ScanSettings.Builder scanSettingsBuilder = new ScanSettings.Builder()
.SetScanMode(global::Android.Bluetooth.LE.ScanMode.Balanced);
// return batched scan results periodically if supported on the BLE chip
if (BluetoothAdapter.DefaultAdapter.IsOffloadedScanBatchingSupported)
{
scanSettingsBuilder.SetReportDelay((long)(ScanDurationMS / 2.0));
}
// start a fresh manager delegate to collect/read results
_bluetoothScannerCallback = new AndroidBluetoothClientScannerCallback(_deviceIdService, _deviceIdCharacteristic, this);
BluetoothAdapter.DefaultAdapter.BluetoothLeScanner.StartScan(scanFilters, scanSettingsBuilder.Build(), _bluetoothScannerCallback);
}
if (ScanMode.HasFlag(BluetoothScanModes.Classic))
{
BluetoothAdapter.DefaultAdapter.StartDiscovery();
}
TaskCompletionSource <bool> scanCompletionSource = new TaskCompletionSource <bool>();
cancellationToken.Register(() =>
{
try
{
if (ScanMode.HasFlag(BluetoothScanModes.LE))
{
BluetoothAdapter.DefaultAdapter.BluetoothLeScanner.StopScan(_bluetoothScannerCallback);
}
else if (ScanMode.HasFlag(BluetoothScanModes.Classic) && BluetoothAdapter.DefaultAdapter.IsDiscovering)
{
BluetoothAdapter.DefaultAdapter.CancelDiscovery();
}
}
catch (Exception ex)
{
SensusServiceHelper.Get().Logger.Log("Exception while stopping scan: " + ex.Message, LoggingLevel.Normal, GetType());
}
finally
{
scanCompletionSource.TrySetResult(true);
}
});
await scanCompletionSource.Task;
}
catch (Exception ex)
{
SensusServiceHelper.Get().Logger.Log("Exception while scanning: " + ex.Message, LoggingLevel.Normal, GetType());
}
}
}