/// <summary>
/// Invoked when this page is navigated away from.
/// </summary>
/// <param name="e">Event data that describes how this page was reached. The Parameter
/// property is typically used to configure the page.</param>
protected override void OnNavigatedFrom(NavigationEventArgs e)
{
// Unsubscribe from the OnInkLevelReceived event.
if (printHelper != null)
{
printHelper.OnInkLevelReceived -= OnInkLevelReceived;
printHelper = null;
}
}
public Preferences()
{
this.InitializeComponent();
configuration = rootPage.Config;
printerExtensionContext = rootPage.Context;
printHelper = new PrintHelperClass(printerExtensionContext);
// Disable scenario navigation by hiding the scenario list UI elements
((UIElement)rootPage.FindName("Scenarios")).Visibility = Windows.UI.Xaml.Visibility.Collapsed;
((UIElement)rootPage.FindName("ScenarioListLabel")).Visibility = Windows.UI.Xaml.Visibility.Collapsed;
((UIElement)rootPage.FindName("DescriptionText")).Visibility = Windows.UI.Xaml.Visibility.Collapsed;
DisplaySettings();
}
/// <summary>
/// Sends a ink status query to the selected printer.
/// </summary>
/// <param name="sender" type = "Windows.UI.Xaml.Controls.Button">A pointer to the button that the user hit to enumerate printers</param>
/// <param name="e">Arguments passed in by the event.</param>
void GetInkStatus(object sender, RoutedEventArgs e)
{
if (AssociatedPrinters.Items.Count > 0)
{
// Get the printer that the user has selected to query.
ComboBoxItem selectedItem = AssociatedPrinters.SelectedItem as ComboBoxItem;
// The interfaceId is retrieved from the detail field.
string interfaceId = selectedItem.DataContext as string;
try
{
// Unsubscribe existing ink level event handler, if any.
if (printHelper != null)
{
printHelper.OnInkLevelReceived -= OnInkLevelReceived;
printHelper = null;
}
object context = Windows.Devices.Printers.Extensions.PrintExtensionContext.FromDeviceId(interfaceId);
// Use the PrinterHelperClass to retrieve the bidi data and display it.
printHelper = new PrintHelperClass(context);
try
{
printHelper.OnInkLevelReceived += OnInkLevelReceived;
printHelper.SendInkLevelQuery();
rootPage.NotifyUser("Ink level query successful", NotifyType.StatusMessage);
}
catch (Exception)
{
rootPage.NotifyUser("Ink level query unsuccessful", NotifyType.ErrorMessage);
}
}
catch (Exception)
{
rootPage.NotifyUser("Error retrieving PrinterExtensionContext from InterfaceId", NotifyType.ErrorMessage);
}
}
}