private async void TaskInstance_Canceled(IBackgroundTaskInstance sender, BackgroundTaskCancellationReason reason)
{
await SharedState.LogAsync($"BackgroundScanner ({sender.InstanceId}): Background task cancelled. Reason: {reason}");
_taskInstance.Canceled -= TaskInstance_Canceled;
_taskInstance.Progress = 0;
_deferral.Complete();
}
private async void OnResuming(object sender, object e)
{
await SharedState.LogAsync("Scannit: RESUMING!");
await SharedState.SetAsync(SharedState.IsApplicationInForeground, true);
await Scanner.StartScanner();
}
public async void Run(IBackgroundTaskInstance taskInstance)
{
await SharedState.LogAsync($"BackgroundScanner ({taskInstance.InstanceId}): Starting run of background task...");
_taskInstance = taskInstance;
_deferral = taskInstance.GetDeferral();
_taskInstance.Progress = 1;
_taskInstance.Canceled += TaskInstance_Canceled;
string selector = SmartCardReader.GetDeviceSelector();
DeviceInformationCollection devices = await DeviceInformation.FindAllAsync(selector);
var reader = await SmartCardReader.FromIdAsync(devices.FirstOrDefault().Id);
await SharedState.LogAsync($"BackgroundScanner ({taskInstance.InstanceId}): Got card reader device.");
reader.CardAdded += Reader_CardAdded;
}
private async void Reader_CardAdded(SmartCardReader sender, CardAddedEventArgs args)
{
await SharedState.LogAsync($"BackgroundScanner ({_taskInstance.InstanceId}): CardAdded event fired.");
try
{
TravelCard card = await CardOperations.ReadTravelCardAsync(args.SmartCard);
if (card != null)
{
await SharedState.LogAsync($"BackgroundScanner ({_taskInstance.InstanceId}): Successful read card.");
Task updateCardTask = SharedState.SetAsync(SharedState.LastSeenCard, card.RawValues);
await SharedState.LogAsync($"BackgroundScanner ({_taskInstance.InstanceId}): LastSeenCard updated.");
Task updateTimestampTask = SharedState.SetAsync(SharedState.LastSeenTimestamp, DateTimeOffset.UtcNow);
await SharedState.LogAsync($"BackgroundScanner ({_taskInstance.InstanceId}): LastSeenTimestamp updated.");
if (await SharedState.GetAsync <bool>(SharedState.IsApplicationInForeground))
{
await SharedState.LogAsync($"BackgroundScanner ({_taskInstance.InstanceId}): Application is in the foreground. Changed Progress value.");
_taskInstance.Progress = 2;
}
else
{
await SharedState.LogAsync($"BackgroundScanner ({_taskInstance.InstanceId}): Application is in the background. Post toast notification.");
PostToastNotification(card);
}
}
}
catch (Exception ex)
{
await SharedState.LogAsync($"BackgroundScanner ({_taskInstance.InstanceId}): Failed to read travel card! Exception: {ex}\nStack trace: {ex.StackTrace}");
}
}
private async void OnSuspending(object sender, SuspendingEventArgs e)
{
SuspendingDeferral deferral = e.SuspendingOperation.GetDeferral();
var newSession = new ExtendedExecutionSession
{
Reason = ExtendedExecutionReason.SavingData
};
newSession.Revoked += NewSession_Revoked;
ExtendedExecutionResult result = await newSession.RequestExtensionAsync();
if (result == ExtendedExecutionResult.Allowed)
{
await SharedState.LogAsync("Scannit: SUSPENDING!");
await SharedState.SetAsync(SharedState.IsApplicationInForeground, false);
newSession.Revoked -= NewSession_Revoked;
newSession.Dispose();
newSession = null;
}
deferral.Complete();
}
