/// <summary>
/// Invoked when this page is about to be displayed in a Frame.
/// </summary>
/// <param name="e">Event data that describes how this page was reached.
/// This parameter is typically used to configure the page.</param>
protected override async void OnNavigatedTo(NavigationEventArgs e)
{
// Request the right to have background tasks run in the future. This need only be done once
// after the app is installed, but it is harmless to do it every time the app is launched.
if (await BackgroundExecutiondManager.RequestAccessAsync() == BackgroundAccessStatus.Denied)
{
// TODO: What?
}
// Acquire the set of background tasks that we already have registered. Store them into a dictionary, keyed
// by task name. (For each LE device, we will use a task name that is derived from its Bluetooth address).
Dictionary<string, BackgroundTaskRegistration> taskRegistrations = new Dictionary<string, BackgroundTaskRegistration>();
foreach (BackgroundTaskRegistration reg in BackgroundTaskRegistration.AllTasks.Values)
{
taskRegistrations[reg.Name] = reg;
}
// Get the list of paired Bluetooth LE devicdes, and add them to our 'devices' list. Associate each device with
// its pre-existing registration if any, and remove that registration from our dictionary.
Devices.Clear();
foreach (DeviceInformation di in await DeviceInformation.FindAllAsync(BluetoothLEDevice.GetDeviceSelector()))
{
BluetoothLEDevice bleDevice = await BluetoothLEDevice.FromIdAsync(di.Id);
Racer device = new Racer(bleDevice);
if (taskRegistrations.ContainsKey(device.TaskName))
{
device.TaskRegistration = taskRegistrations[device.TaskName];
taskRegistrations.Remove(device.TaskName);
}
Devices.Add(device);
}
// Unregister any remaining background tasks that remain in our dictionary. These are tasks that we registered
// for Bluetooth LE devices that have since been unpaired.
foreach (BackgroundTaskRegistration reg in taskRegistrations.Values)
{
reg.Unregister(false);
}
}
/// <summary>
/// Invoked when this page is about to be displayed in a Frame.
/// </summary>
/// <param name="e">Event data that describes how this page was reached.
/// This parameter is typically used to configure the page.</param>
protected override void OnNavigatedTo(NavigationEventArgs e)
{
Device = (Racer)e.Parameter;
}