protected override void OnAppearing()
{
_discoveryService = new DiscoveryService();
_discoveryService.OnDevice += async(sender, device) =>
_devicesSource.Add(await TargetDevice.FromDiscoveredDeviceAsync(device.DiscoveredDevice));
_discoveryService.OnDeviceDisconnect += (sender, device) =>
_devicesSource.RemoveMany(_devicesSource.Items.Where(x => x.Usn == device.DiscoveredDevice.Usn));
base.OnAppearing();
}
private Task SearchAsync()
{
Device.BeginInvokeOnMainThread(() => { ViewModel.Device = "Searching"; });
var tcs = new TaskCompletionSource <bool>();
Task.Run(async() =>
{
using (var discoveryService = new DiscoveryService())
using (var observer = new AnonymousObserver <DeviceAvailableEventArgs>(async e =>
{
State.PreviousDevice = await TargetDevice.FromDiscoveredDeviceAsync(e.DiscoveredDevice);
tcs.SetResult(true);
}))
{
var pipeline = Observable
.FromEventPattern <DeviceAvailableEventArgs>(
handler => discoveryService.OnDevice += handler,
handler => discoveryService.OnDevice -= handler
)
.Select(x => x.EventArgs);
if (State.PreviousDevice == null)
{
pipeline = pipeline
.Take(1);
}
if (State?.PreviousDevice?.Usn != null)
{
pipeline = pipeline
.Where(x => x.DiscoveredDevice.Usn == State.PreviousDevice.Usn)
.Take(1);
}
pipeline.Subscribe(observer);
await discoveryService.SearchAsync();
tcs.SetResult(true);
}
});
return(tcs.Task);
}
