void Page_Unloaded(object sender, RoutedEventArgs e)
{
if (inkRecognizer != null)
{
// Calling Dispose() on InkRecognizer to dispose of resources being used by HttpClient
inkRecognizer.Dispose();
inkRecognizer = null;
}
// Dispose Win2D resources to avoid memory leak
// Reference: https://microsoft.github.io/Win2D/html/RefCycles.htm
var resultCanvas = this.FindName("resultCanvas") as CanvasControl;
resultCanvas.RemoveFromVisualTree();
resultCanvas = null;
}
protected override async void OnNavigatedTo(NavigationEventArgs e)
{
if (!previouslyLoaded)
{
var file = await StorageFile.GetFileFromApplicationUriAsync(new Uri("ms-appx:///Assets/InkRecognizerSampleInstructions.gif"));
if (file != null)
{
using (var stream = await file.OpenSequentialReadAsync())
{
await inkCanvas.InkPresenter.StrokeContainer.LoadAsync(stream);
}
}
previouslyLoaded = true;
}
// When the page is Unloaded, InkRecognizer and the Win2D CanvasControl are disposed. To preserve the state of the page we need to re-instantiate these objects.
// In the case of the Win2D CanvasControl, a new UI Element needs to be created/appended to the page as well
string endpoint = localSettings.Values["InkRecognizerEndpoint"] as string;
string apiKey = localSettings.Values["InkRecognizerApiKey"] as string;
if (string.IsNullOrEmpty(endpoint) || !Uri.IsWellFormedUriString(endpoint, UriKind.Absolute))
{
await new MessageDialog("Ensure you have a valid URI set in the Settings page.", "Invalid or Missing URI").ShowAsync();
}
else
{
inkRecognizer = new InkRecognizer(endpoint, apiKey);
}
var resultCanvas = new CanvasControl();
resultCanvas.Name = "resultCanvas";
resultCanvas.Draw += ResultCanvas_Draw;
resultCanvas.SetValue(Grid.RowProperty, 0);
resultCanvasGrid.Children.Add(resultCanvas);
base.OnNavigatedTo(e);
}
