OcrEngineManager Class

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

[TestMethod]
public async Task MultiThreadedOcrExample()
{
   try
   {
      string imageFileName = @"Multipage.tif";
      bool usePdf = true;
      System.Diagnostics.Debug.WriteLine(string.Format("Image: " + imageFileName));

      // First get the number of pages in the documents, then do each page in its own thread
      int pageCount;

      StorageFile imageFile = await Tools.AppInstallFolder.GetFileAsync(@"Assets\" + imageFileName);
      ILeadStream leadStream = LeadStreamFactory.Create(imageFile);
      using (IDisposable leadStreamDisposable = leadStream as IDisposable)
      {
         using (RasterCodecs codecs = new RasterCodecs())
         {
            System.Diagnostics.Debug.WriteLine("RasterCodecs.GetInformationAsync");
            using (CodecsImageInfo imageInfo = await codecs.GetInformationAsync(leadStream, true, 1))
            {
               pageCount = imageInfo.TotalPages;

               System.Diagnostics.Debug.WriteLine(string.Format("{0} pages in the file", pageCount));
            }
         }
      }

      // Create a LEADTOOLS IOcrEngine
      string engineDirectory = Path.Combine(Tools.AppInstallFolder.Path, @"OcrRuntime");

      IOcrEngine ocrEngine = OcrEngineManager.CreateEngine(OcrEngineType.Advantage, false);
      using (IDisposable ocrEngineDisposable = ocrEngine as IDisposable)
      {
         System.Diagnostics.Debug.WriteLine("IOcrEngine.Startup");
         ocrEngine.Startup(null, null, String.Empty, engineDirectory);

         // Counter to tell us how many pages are left
         int pagesLeft = pageCount;
         // Event to trigger when all pages are completed
         AutoResetEvent completedEvent = new AutoResetEvent(false);

         // Run a thread for each job
         for (int pageNumber = 1; pageNumber <= pageCount; pageNumber++)
         {
            int workPageNumber = pageNumber;
            Task.Factory.StartNew(async () =>
            {
               System.Diagnostics.Debug.WriteLine(string.Format("Thread working on page {0} started", workPageNumber));

               // Create the document
               try
               {
                  IOcrDocument ocrDocument = ocrEngine.DocumentManager.CreateDocument();
                  using (IDisposable ocrDocumentDisposable = ocrDocument as IDisposable)
                  {
                     IOcrPage ocrPage = null;

                     // Load the page
                     RasterCodecs codecs = ocrDocument.RasterCodecsInstance;
                     ILeadStream pageStream = LeadStreamFactory.Create(imageFile);
                     using (IDisposable pageStreamDisposable = pageStream as IDisposable)
                     {
                        System.Diagnostics.Debug.WriteLine(string.Format("Thread loading page {0}", workPageNumber));
                        using (RasterImage pageImage = await codecs.LoadAsync(pageStream, 0, CodecsLoadByteOrder.BgrOrGray, workPageNumber, workPageNumber))
                        {
                           // Add it to the document
                           System.Diagnostics.Debug.WriteLine(string.Format("Adding page {0}", workPageNumber));
                           ocrPage = ocrDocument.Pages.AddPage(pageImage, null);
                        }
                     }

                     System.Diagnostics.Debug.WriteLine(string.Format("Recognize page {0}", workPageNumber));
                     ocrPage.Recognize(null);

                     System.Diagnostics.Debug.WriteLine(string.Format("Saving page {0}", workPageNumber));
                     string outputFileName;
                     DocumentFormat format;
                     if (usePdf)
                     {
                        outputFileName = string.Format("Page{0}.pdf", workPageNumber);
                        format = DocumentFormat.Pdf;
                     }
                     else
                     {
                        outputFileName = string.Format("Page{0}.txt", workPageNumber);
                        format = DocumentFormat.Text;
                     }

                     StorageFile outputFile = await Tools.AppLocalFolder.CreateFileAsync(outputFileName, CreationCollisionOption.ReplaceExisting);
                     leadStream = LeadStreamFactory.Create(outputFile);
                     using (IDisposable leadStreamDisposable = leadStream as IDisposable)
                     {
                        System.Diagnostics.Debug.WriteLine("IOcrDocument.SaveAsync");
                        System.Diagnostics.Debug.WriteLine(outputFile.Path);
                        // take the comment out, it hangs after saving the first file
                        await ocrDocument.SaveAsync(leadStream, format, null);
                     }
                  }
               }
               catch (Exception ex)
               {
                  OutputError(ex);
               }
               finally
               {
                  System.Diagnostics.Debug.WriteLine(string.Format("Thread working on page {0} completed", workPageNumber));

                  // Decrement the counter
                  if (Interlocked.Decrement(ref pagesLeft) == 0)
                  {
                     // We are done
                     completedEvent.Set();
                  }
               }
            });
         }

         // Wait on all work to finish
         completedEvent.WaitOne();
      }
   }
   catch (Exception ex)
   {
      OutputError(ex);
   }
}

private void OutputError(Exception error)
{
   string message = string.Empty;

   RasterException rasterException = RasterException.FromHResult(error.HResult);
   if (rasterException != null)
      message = string.Format("ERROR LEADTOOLS: {0} - {1}", rasterException.Code, rasterException.Message);
   else
      message = string.Format("ERROR: {0} - {1}", error.HResult, error.Message);

   System.Diagnostics.Debug.WriteLine(message, true);
}