OcrEngineManager Class

Provides methods to create OCR engine instances.

Object Model

Syntax

Visual Basic
C#
WinRT C#
WinRT JavaScript
C++

public static class OcrEngineManager

'Declaration
 
Public MustInherit NotInheritable Class OcrEngineManager

'Usage
 
Dim instance As OcrEngineManager

public sealed static class OcrEngineManager

function Leadtools.Forms.Ocr.OcrEngineManager()

public ref class OcrEngineManager abstract sealed

Remarks

The OcrEngineManager class and its methods are your entry point to using the Leadtools.Forms.Ocr class library.

This class provides the methods you need to create an object of the IOcrEngine interface. Afterwards, you can use the properties and methods of this interface to perform your OCR tasks.

Based on the engine type passed to the CreateEngine methods, OcrEngineManager will load the OCR engine defined in one of the supporting assemblies and return an interface to IOcrEngine. Use this interface and its included types to start using the Leadtools.Forms.Ocr class library. For more information about the engine types, refer to OcrEngineType.

The CreateEngine method lets you create an instance of IOcrEngine, loading the corresponding Leadtools.Forms.Ocr.[EngineName].dll assembly using the .NET System.Reflection.Assembly.Load(string assemblyString) method. You cannot unload this assembly once it has been successfully loaded.

Depending on your application requirement, platform and OCR engine type; a "thunk" mechanism might be required. Refer to Multi-Threading with LEADTOOLS OCR for more information and on how to use the useThunkServer parameter of OcrEngineManager.CreateEngine.

Example

Visual Basic
C#
WinRT C#
WinRT JavaScript
Silverlight C#
Silverlight VB

Copy Code

Private Structure MyThreadData
      Public ImageFileName As String
      Public WaitHandle As AutoResetEvent
   End Structure
   Public Sub MultiThreadedOcrExample()
      ' The image file names we are going to OCR and convert to PDF
      Dim tifFileNames() As String = _
      { _
         Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.tif"), _
         Path.Combine(LEAD_VARS.ImagesDir, "Ocr2.tif"), _
         Path.Combine(LEAD_VARS.ImagesDir, "Ocr3.tif"), _
         Path.Combine(LEAD_VARS.ImagesDir, "Ocr4.tif") _
      }

      Dim threadCount As Integer = tifFileNames.Length

      ' Create the thread
      Dim threads(threadCount - 1) As Thread
      Dim waitHandles(threadCount - 1) As AutoResetEvent
      For i As Integer = 0 To threadCount - 1
         threads(i) = New Thread(AddressOf MyThreadProc)
         threads(i).Name = "OCR thread + " + i.ToString()

         waitHandles(i) = New AutoResetEvent(False)
      Next

      Console.WriteLine("Starting the threads and waiting...")

      ' Start the threads
      For i As Integer = 0 To threadCount - 1
         Dim threadData As New MyThreadData()
         threadData.ImageFileName = tifFileNames(i)
         threadData.WaitHandle = waitHandles(i)
         threads(i).Start(threadData)
      Next

      ' Wait till all threads are done
      WaitHandle.WaitAll(waitHandles)
      Console.WriteLine("All threads finished")
   End Sub

   Private Sub MyThreadProc(ByVal data As Object)
      ' Grab the data
      Dim threadData As MyThreadData = CType(data, MyThreadData)
      Dim imageFileName As String = threadData.ImageFileName

      ' Show a status message
      Console.WriteLine("Begin: {0}", imageFileName)

      ' Create an instance of the OCR engine using the LEADTOOLS Thunk Server
      Using ocrEngine As IOcrEngine = OcrEngineManager.CreateEngine(OcrEngineType.Plus, True)
         ' Start the engine using default parameters
         ocrEngine.Startup(Nothing, Nothing, Nothing, Nothing)

         ' Get the PDf file name
         Dim pdfFileName As String = Path.ChangeExtension(imageFileName, "pdf")

         ' Create an OCR document
         Using ocrDocument As IOcrDocument = ocrEngine.DocumentManager.CreateDocument()
            ' Add a page to the document
            Dim ocrPage As IOcrPage = ocrDocument.Pages.AddPage(imageFileName, Nothing)

            ' Recognize the page
            ' Note, Recognize can be called without calling AutoZone or manually adding zones. The engine will
            ' check and automatically auto-zones the page
            ocrPage.Recognize(Nothing)

            ' Save the document we have as PDF
            ocrDocument.Save(pdfFileName, DocumentFormat.Pdf, Nothing)
         End Using

         ' Shutdown the engine
         ' Note: calling Dispose will also automatically shutdown the engine if it has been started
         ocrEngine.Shutdown()
      End Using

      Console.WriteLine("End: {0}", imageFileName)

      ' Singal the main thread
      threadData.WaitHandle.Set()
   End Sub

Public NotInheritable Class LEAD_VARS
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images"
End Class

private struct MyThreadData
   {
      public string ImageFileName;
      public AutoResetEvent WaitHandle;
   }
   public void MultiThreadedOcrExample()
   {
      // The image file names we are going to OCR and convert to PDF
      string[] tifFileNames =
      {
         Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.tif"),
         Path.Combine(LEAD_VARS.ImagesDir, "Ocr2.tif"),
         Path.Combine(LEAD_VARS.ImagesDir, "Ocr3.tif"),
         Path.Combine(LEAD_VARS.ImagesDir, "Ocr4.tif")
      };

      int threadCount = tifFileNames.Length;

      // Create the thread
      Thread[] threads = new Thread[threadCount];
      AutoResetEvent[] waitHandles = new AutoResetEvent[threadCount];
      for(int i = 0; i < threadCount; i++)
      {
         threads[i] = new Thread(new ParameterizedThreadStart(MyThreadProc));
         threads[i].Name = "OCR thread + " + i.ToString();

         waitHandles[i] = new AutoResetEvent(false);
      }

      Console.WriteLine("Starting the threads and waiting...");

      // Start the threads
      for(int i = 0; i < threadCount; i++)
      {
          MyThreadData threadData = new MyThreadData();
         threadData.ImageFileName = tifFileNames[i];
         threadData.WaitHandle = waitHandles[i];
         threads[i].Start(threadData);
      }

      // Wait till all threads are done
      WaitHandle.WaitAll(waitHandles);
      Console.WriteLine("All threads finished");
   }

   private void MyThreadProc(object data)
   {
      // Grab the data
       MyThreadData threadData = (MyThreadData)data;
      string imageFileName = threadData.ImageFileName;

      // Show a status message
      Console.WriteLine("Begin: {0}", imageFileName);

      // Create an instance of the OCR engine using the LEADTOOLS Thunk Server
      using(IOcrEngine ocrEngine = OcrEngineManager.CreateEngine(OcrEngineType.Plus, true))
      {
         // Start the engine using default parameters
         ocrEngine.Startup(null, null, null, null);

         // Get the PDf file name
         string pdfFileName = Path.ChangeExtension(imageFileName, "pdf");

         // Create an OCR document
         using(IOcrDocument ocrDocument = ocrEngine.DocumentManager.CreateDocument())
         {

            // Add a page to the document
            IOcrPage ocrPage = ocrDocument.Pages.AddPage(imageFileName, null);

            // Recognize the page
            // Note, Recognize can be called without calling AutoZone or manually adding zones. The engine will
            // check and automatically auto-zones the page
            ocrPage.Recognize(null);

            // Save the document we have as PDF
            ocrDocument.Save(pdfFileName, DocumentFormat.Pdf, null);
         }

         // Shutdown the engine
         // Note: calling Dispose will also automatically shutdown the engine if it has been started
         ocrEngine.Shutdown();
      }

      Console.WriteLine("End: {0}", imageFileName);

      // Singal the main thread
      threadData.WaitHandle.Set();
   }

static class LEAD_VARS
{
   public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images";
}

[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);
}

Requirements

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

OcrEngineManager Members
Leadtools.Forms.Ocr Namespace
OcrEngineType Enumeration
IOcrEngine Interface
Programming with the LEADTOOLS .NET OCR
Creating an OCR Engine Instance
Starting and Shutting Down the OCR Engine
Multi-Threading with LEADTOOLS OCR
LEADTOOLS OCR Thunk Server
Files to be Included with Your Application