WinRT OCR for Windows Store Apps with LEADTOOLS

using System;
using System.IO;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Navigation;

// The Blank Page item template is documented at http://go.microsoft.com/fwlink/?LinkId=234238

using Windows.Foundation;
using Windows.UI.Core;
using Windows.UI.Notifications;
using Windows.Storage.Pickers;
using Windows.Data.Xml.Dom;



using Leadtools;
using Leadtools.Codecs;
using Leadtools.Controls;
using Leadtools.Forms.DocumentWriters;
using Leadtools.Forms.Ocr;

namespace LEADTOOLSWinRTOCR
{
   /// <summary>
   /// An empty page that can be used on its own or navigated to within a Frame.
   /// </summary>
   public sealed partial class MainPage : Page
   {
      // OCR engine instance
      private IOcrEngine _ocrEngine;
      // Current OCR document
      private IOcrDocument _ocrDocument;
      // Current OCR page
      private IOcrPage _ocrPage;

      public MainPage()
      {
         this.InitializeComponent();
      }

      // Save LEADTOOLS image formats
      private struct ImageFormat
      {
         public string Name;
         public string Extension;
         public RasterImageFormat Format;

         public ImageFormat(string name, string extension, RasterImageFormat format)
         {
            Name = name;
            Extension = extension;
            Format = format;
         }

         public override string ToString()
         {
            return Name;
         }
      };

      private static ImageFormat[] _imageFormats =
      {
         new ImageFormat("PDF", ".pdf", RasterImageFormat.RasPdf),
         new ImageFormat("BMP", ".bmp", RasterImageFormat.Bmp),
         new ImageFormat("JPEG", ".jpg", RasterImageFormat.Jpeg422),
         new ImageFormat("TIFF", ".tif", RasterImageFormat.CcittGroup4),
         new ImageFormat("PNG", ".png", RasterImageFormat.Png),
      };

      /// <summary>
      /// Invoked when this page is about to be displayed in a Frame.
      /// </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 OnNavigatedTo(NavigationEventArgs e)
      {
         // Initialize LEADTOOLS support
         RasterSupport.Initialize();

         try
         {
            // Create an instance of the engine
            string strEngineDirectory = Path.Combine(Windows.ApplicationModel.Package.Current.InstalledLocation.Path, @"OCR");
            _ocrEngine = OcrEngineManager.CreateEngine(OcrEngineType.Advantage, false);
            _ocrEngine.Startup(null, null, string.Empty, strEngineDirectory);

            // Create the OCR document
            _ocrDocument = _ocrEngine.DocumentManager.CreateDocument();

            ShowMessage("OCR engine started");
         }
         catch (Exception ex)
         {
            ShowError(ex);
         }
      }

      private void rasterImageViewer1_Loaded(object sender, RoutedEventArgs e)
      {
         // Set up rubber band as the interactive mode

         ImageViewerRubberBandInteractiveMode rubberband = new ImageViewerRubberBandInteractiveMode();
         rubberband.RubberBandCompleted += delegate(object rubberBandSender, ImageViewerRubberBandEventArgs rubberBandEventArgs)
         {
            // Get the rubber band rectangle
            Rect bounds = new Rect(rubberBandEventArgs.Point1, rubberBandEventArgs.Point2);

            if (bounds.Width > 1 && bounds.Height > 1)
            {
               // Convert it to image coordinates
               bounds = rasterImageViewer1.ConvertRect(CoordinateType.Control, CoordinateType.Image, bounds);
               RecognizeText(bounds);
            }
         };

         rasterImageViewer1.DefaultInteractiveMode = rubberband;
      }

      private async void LoadButton_Click(object sender, RoutedEventArgs e)
      {
         // Show the file picker
         var picker = new FileOpenPicker();
         picker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
         picker.ViewMode = PickerViewMode.List;
         foreach (var imageFormat in _imageFormats)
            picker.FileTypeFilter.Add(imageFormat.Extension);

         try
         {
            var file = await picker.PickSingleFileAsync();
            if (file == null)
               return;

            // Create a LEADTOOLS stream from the file
            ILeadStream leadStream = LeadStreamFactory.Create(file);

            // Get the RasterCodecs object to load the image from the OCR engine
            RasterCodecs codecs = _ocrEngine.RasterCodecsInstance;

            // Load the image (first page only)
            RasterImage rasterImage = await codecs.LoadAsync(leadStream, 0, CodecsLoadByteOrder.BgrOrGray, 1, 1);

            (leadStream as IDisposable).Dispose();

            // Add it to the OCR engine

            // Check if we have previous pages, remove them
            _ocrDocument.Pages.Clear();
            _ocrPage = _ocrDocument.Pages.AddPage(rasterImage, null);

            await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, delegate()
            {
               rasterImageViewer1.Image = rasterImage;
               rasterImageViewer1.Zoom(ImageViewerSizeMode.Fit, 1, rasterImageViewer1.DefaultZoomOrigin);
            });
         }
         catch (Exception ex)
         {
            ShowError(ex);
         }
      }

      private async void OcrPdfButton_Click(object sender, RoutedEventArgs e)
      {
         TextResults.Text = "";

         if (_ocrPage == null)
         {
            ShowMessage("Load an image first...");
            return;
         }

         try
         {
            // Pick the output file
            var picker = new FileSavePicker();
            picker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
            picker.FileTypeChoices.Add("PDF", new string[] { ".pdf" });
            picker.DefaultFileExtension = ".pdf";

            var file = await picker.PickSaveFileAsync();
            if(file == null)
               return;

            // Auto-zone the page
            _ocrPage.AutoZone(null);

            // Recognize the page
            _ocrPage.Recognize(null);

            // Create a LEADTOOLS stream from the file
            ILeadStream leadStream = LeadStreamFactory.Create(file);

            // Set PDF output options, use PDF/A
            PdfDocumentOptions options = _ocrEngine.DocumentWriterInstance.GetOptions(DocumentFormat.Pdf) as PdfDocumentOptions;
            options.DocumentType = PdfDocumentType.PdfA;
            _ocrEngine.DocumentWriterInstance.SetOptions(DocumentFormat.Pdf, options);

            // Save the OCR'd document as searchable PDF
            await _ocrDocument.SaveAsync(leadStream, DocumentFormat.Pdf, null);

            // Show a compeleted message
            ShowMessage("Recognized as PDF");
         }
         catch (Exception ex)
         {
            ShowError(ex);
         }
      }

      private void OcrTextButton_Click(object sender, RoutedEventArgs e)
      {
         TextResults.Text = "";

         if (_ocrPage == null)
         {
            ShowMessage("Load an image first...");
            return;
         }

         RecognizeText(Rect.Empty);
      }

      private void RecognizeText(Rect bounds)
      {
         try
         {
            // If we have a bounds, only recognize that area, otherwise, recognize all

            if (bounds.IsEmpty)
            {
               // No area, auto-zone
               _ocrPage.AutoZone(null);
            }
            else
            {
               // Clear the zones first
               _ocrPage.Zones.Clear();

               // Add our bounds
               OcrZone zone = OcrTypeManager.CreateDefaultOcrZone();
               zone.ZoneType = OcrZoneType.Text;
               zone.Bounds = LeadRectHelper.Create((int)bounds.X, (int)bounds.Y, (int)bounds.Width, (int)bounds.Height);
               _ocrPage.Zones.Add(zone);
            }

            // Recognize the page and get the results as text
            TextResults.Text = _ocrPage.RecognizeText(null);
            ShowMessage("Recognized as Text");
         }
         catch (Exception ex)
         {
            ShowError(ex);
         }
      }

      private async void ShowMessage(string message)
      {
         // We will use a toast to show the error message
         // Make sure the app is "Toast Capable"
         await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, delegate()
         {
            XmlDocument toastXml = ToastNotificationManager.GetTemplateContent(ToastTemplateType.ToastImageAndText01);
            XmlNodeList textElements = toastXml.GetElementsByTagName("text");

            textElements.Item(0).AppendChild(toastXml.CreateTextNode(message));

            // Create a toast from the Xml, then create a ToastNotifier object 
            // to show the toast
            ToastNotification toast = new ToastNotification(toastXml);

            // If you have other applications in your package, you can specify 
            // the AppId of the app to create a ToastNotifier for that application
            ToastNotificationManager.CreateToastNotifier().Show(toast);
         });
      }

      private void ShowError(Exception error)
      {
         // Get the error message
         string errorMessage = null;

         // Check if it is a LEADTOOLS exception
         RasterException rasterException = RasterException.FromHResult(error.HResult);
         if (rasterException != null)
            errorMessage = string.Format("LEADTOOLS Error: {0}\n{1}", rasterException.Code, rasterException.Message);
         else
            errorMessage = error.Message;

         ShowMessage(errorMessage);
      }
   }
}