protected async override void OnNavigatedTo(NavigationEventArgs e)
{
// Set the page to standby mode to start off with
this.GoToVisualState("Standby");
_ctsVideoMonitor = new CancellationTokenSource();
// Initialize the text-to-speech class instance. It uses the MediaElement on the page to play sounds thus you need to pass it a reference to.
_tts = new TextToSpeech(this.media, this.Dispatcher);
// Initialize the speech-to-text class instance which is used to recognize speech commands by the customer
_speechToText = new SpeechToText(
_SpeechToTextLanguageName,
_SpeechToTextInitialSilenceTimeoutInSeconds,
_SpeechToTextBabbleTimeoutInSeconds,
_SpeechToTextEndSilenceTimeoutInSeconds);
await _speechToText.InitializeRecognizerAsync();
_speechToText.OnHypothesis += _speechToText_OnHypothesis;
_speechToText.CapturingStarted += _speechToText_CapturingStarted;
_speechToText.CapturingEnded += _speechToText_CapturingEnded;
// Landscape preference set to landscape
DisplayInformation.AutoRotationPreferences = DisplayOrientations.Landscape;
// Keeps the screen alive i.e. prevents screen from going to sleep
_displayRequest = new DisplayRequest();
_displayRequest.RequestActive();
// Find all the video cameras on the device
var cameras = await DeviceInformation.FindAllAsync(DeviceClass.VideoCapture);
// Choose the first externally plugged in camera found
var preferredCamera = cameras.FirstOrDefault(deviceInfo => deviceInfo.EnclosureLocation == null);
// If no external camera, choose the front facing camera ELSE choose the first available camera found
if (preferredCamera == null)
{
preferredCamera = cameras.FirstOrDefault(deviceInfo => deviceInfo.EnclosureLocation?.Panel == Windows.Devices.Enumeration.Panel.Front) ?? cameras.FirstOrDefault();
}
// No camera found on device
if (preferredCamera == null)
{
Debug.WriteLine("No camera found on device!");
return;
}
// Initialize and start the camera video stream into the app preview window
_mediaCapture = new MediaCapture();
await _mediaCapture.InitializeAsync(new MediaCaptureInitializationSettings()
{
StreamingCaptureMode = StreamingCaptureMode.Video,
VideoDeviceId = preferredCamera.Id
});
videoPreview.Source = _mediaCapture;
await _mediaCapture.StartPreviewAsync();
// Ensure state is clear
await this.EndSessionAsync();
// Initiate monitoring of the video stream for faces
_faceMonitoringTask = this.FaceMonitoringAsync(_ctsVideoMonitor.Token);
base.OnNavigatedTo(e);
}