protected override void OnNavigatedTo(NavigationEventArgs e)
{
base.OnNavigatedTo(e);
if (EventHandlerForDevice.Current.IsDeviceConnected)
{
SetAllControlsActive(true);
_actionQueue = EventHandlerForDevice.Current.ActionQueue;
DisabledReason.Visibility = Visibility.Collapsed;
}
else
{
SetAllControlsActive(false);
DisabledReason.Visibility = Visibility.Visible;
}
}
/// <summary>
/// This method opens the device using the WinRT Serial API. After the device is opened, save the device
/// so that it can be used across scenarios.
///
/// It is important that the FromIdAsync call is made on the UI thread because the consent prompt can only be displayed
/// on the UI thread.
///
/// This method is used to reopen the device after the device reconnects to the computer and when the app resumes.
/// </summary>
/// <param name="deviceInfo">Device information of the device to be opened</param>
/// <param name="deviceSelector">The AQS used to find this device</param>
/// <returns>True if the device was successfully opened, false if the device could not be opened for well known reasons.
/// An exception may be thrown if the device could not be opened for extraordinary reasons.</returns>
public async Task <bool> OpenDeviceAsync(DeviceInformation deviceInfo, string deviceSelector)
{
Device = await SerialDevice.FromIdAsync(deviceInfo.Id);
bool successfullyOpenedDevice = false;
NotifyType notificationStatus;
string notificationMessage;
// Device could have been blocked by user or the device has already been opened by another app.
if (Device != null)
{
successfullyOpenedDevice = true;
DeviceInformation = deviceInfo;
DeviceSelector = deviceSelector;
Connection = new DeviceConnection(Device);
ActionQueue = new DeviceActionQueue(Connection);
notificationStatus = NotifyType.StatusMessage;
notificationMessage = "Device " + DeviceInformation.Properties["System.ItemNameDisplay"] + " opened";
// Notify registered callback handle that the device has been opened
OnDeviceConnected?.Invoke(this, DeviceInformation);
if (_appSuspendEventHandler == null || _appResumeEventHandler == null)
{
RegisterForAppEvents();
}
// Register for DeviceAccessInformation.AccessChanged event and react to any changes to the
// user access after the device handle was opened.
if (_deviceAccessEventHandler == null)
{
RegisterForDeviceAccessStatusChange();
}
// Create and register device watcher events for the device to be opened unless we're reopening the device
if (_deviceWatcher == null)
{
_deviceWatcher = DeviceInformation.CreateWatcher(deviceSelector);
RegisterForDeviceWatcherEvents();
}
if (!_watcherStarted)
{
// Start the device watcher after we made sure that the device is opened.
StartDeviceWatcher();
}
}
else
{
notificationStatus = NotifyType.ErrorMessage;
var deviceAccessStatus = DeviceAccessInformation.CreateFromId(deviceInfo.Id).CurrentStatus;
switch (deviceAccessStatus)
{
case DeviceAccessStatus.DeniedByUser:
notificationMessage = "Access to the device was blocked by the user : "******"System.ItemNameDisplay"];
break;
case DeviceAccessStatus.DeniedBySystem:
// This status is most likely caused by app permissions (did not declare the device in the app's package.appxmanifest)
// This status does not cover the case where the device is already opened by another app.
notificationMessage = "Access to the device was blocked by the system : " + deviceInfo.Properties["System.ItemNameDisplay"];
break;
default:
notificationMessage = "Unknown error, possibly opened by another app : " + deviceInfo.Properties["System.ItemNameDisplay"];
break;
}
}
MainPage.Current.NotifyUser(notificationMessage, notificationStatus);
return(successfullyOpenedDevice);
}