This example shows how to trap various types of exceptions during OCR operations.

Visual Basic

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Public Sub OcrExceptionExample()    ' Unlock the support needed for LEADTOOLS Plus OCR engine    RasterSupport.Unlock(RasterSupportType.Document, "Replace with your own key here")    RasterSupport.Unlock(RasterSupportType.OcrPlus, "Replace with your own key here")    RasterSupport.Unlock(RasterSupportType.OcrPlusPdfLeadOutput, "Replace with your own key here")    Try       ' Create an instance of the engine       Using ocrEngine As IOcrEngine = OcrEngineManager.CreateEngine(OcrEngineType.Plus, False)          ' Start the engine using default parameters          ocrEngine.Startup(Nothing, Nothing, Nothing, Nothing)          Dim tifFileName As String = LeadtoolsExamples.Common.ImagesPath.Path + "Ocr1.tif"          Dim pdfFileName As String = LeadtoolsExamples.Common.ImagesPath.Path + "Ocr1.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(tifFileName, 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    Catch ex As OcrSupportLockedException       Console.WriteLine("Support is locked. You need to unlock '{0}' in this engine to use this feature", ex.SupportType)    Catch ex As OcrException       Console.WriteLine("OCR Error\nCode: {0}\nMessage:{1}", ex.Code, ex.Message)    Catch ex As RasterException       Console.WriteLine("LEADTOOLS Error\nCode: {0}\nMessage:{1}", ex.Code, ex.Message)    Catch ex As Exception       Console.WriteLine("System Error\nMessage:{0}", ex.Message)    End Try End Sub

C#

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public void OcrExceptionExample()  {     // Unlock the support needed for LEADTOOLS Plus OCR engine     RasterSupport.Unlock(RasterSupportType.Document, "Replace with your own key here");     RasterSupport.Unlock(RasterSupportType.OcrPlus, "Replace with your own key here");     RasterSupport.Unlock(RasterSupportType.OcrPlusPdfLeadOutput, "Replace with your own key here");     try     {        // Create an instance of the engine        using(IOcrEngine ocrEngine = OcrEngineManager.CreateEngine(OcrEngineType.Plus, false))        {           // Start the engine using default parameters           ocrEngine.Startup(null, null, null, null);             string tifFileName = LeadtoolsExamples.Common.ImagesPath.Path + "Ocr1.tif";           string pdfFileName = LeadtoolsExamples.Common.ImagesPath.Path + "Ocr1.pdf";             // Create an OCR document           using(IOcrDocument ocrDocument = ocrEngine.DocumentManager.CreateDocument())           {              // Add a page to the document              IOcrPage ocrPage = ocrDocument.Pages.AddPage(tifFileName, 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();        }     }     catch(OcrSupportLockedException ex)     {        Console.WriteLine("Support is locked. You need to unlock '{0}' in this engine to use this feature", ex.SupportType);     }     catch(OcrException ex)     {        Console.WriteLine("OCR Error\nCode: {0}\nMessage:{1}", ex.Code, ex.Message);     }     catch(RasterException ex)     {        Console.WriteLine("LEADTOOLS Error\nCode: {0}\nMessage:{1}", ex.Code, ex.Message);     }     catch(Exception ex)     {        Console.WriteLine("System Error\nMessage:{0}", ex.Message);     }  }

When a runtime error occurs in the IOcrEngine, an exception of type OcrException is thrown with the engine-specific error code set in the Code member. This error code is engine-specific but a short description can be obtained using the Message property of this class or by using the IOcrEngine.GetErrorCodeString method.

Logic errors such as invalid parameters to methods or invalid operations throw standard .NET exceptions (in this case, ArgumentException and InvalidOperationException respectively Errors caused by loading invalid image files using IOcrEngine.RasterCodecsInstance will throw exceptions of type RasterException. Errors for missing features (support locked) will throw OcrSupportLockedException exceptions. Any other runtime error in the engine will throw an OcrException.

System.Object
   System.Exception
      Leadtools.Forms.Ocr.OcrException

Target Platforms: Microsoft .NET Framework 3.0, Windows XP, Windows Server 2003 family, Windows Server 2008 family

Reference