Public Delegate Function OcrSpellCheckCallback( _
   ByVal engine As IOcrEngine, _
   ByVal page As IOcrPage, _
   ByVal zoneIndex As Integer, _
   ByVal value As String _
) As OcrSpellCheckOpinion

Visual Basic (Usage)	Copy Code
Dim instance As New OcrSpellCheckCallback(AddressOf HandlerMethod)

public delegate OcrSpellCheckOpinion OcrSpellCheckCallback( 
   IOcrEngine engine,
   IOcrPage page,
   int zoneIndex,
   string value
)

public delegate OcrSpellCheckOpinion OcrSpellCheckCallback( 
   IOcrEngine^ engine,
   IOcrPage^ page,
   int zoneIndex,
   String^ value
)

Parameters

engine

The OCR engine instance.

page

The page currently being recognized. To get the index of this page, use OcrDocument.Pages.IndexOf.

zoneIndex

The zero-based index of the zone in page currently being recognized. To get the zone info, use IOcrPage.Zones passing zoneIndex as the index value.

value

Word or line to be checked by the method.

This example attempts to recognize an image having a misspelled word and then uses the user-defined spell checking callback to give an opinion about the engine suggestions.

Visual Basic

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Public Sub OcrSpellCheckWordCallbackExample()    ' 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")    ' Create an image with misspelled number    Dim numberString As String = "123!4"    Dim image As New RasterImage(RasterMemoryFlags.Conventional, 320, 200, 1, RasterByteOrder.Bgr, RasterViewPerspective.TopLeft, Nothing, IntPtr.Zero, 0)    Dim imageRect As New Rectangle(0, 0, image.ImageWidth, image.ImageHeight)    Dim hdc As IntPtr = image.CreateLeadDC()    Using g As Graphics = Graphics.FromHdc(hdc)       g.FillRectangle(Brushes.White, imageRect)       Using f As New Font("Arial", 60, FontStyle.Regular)          Using sf As New StringFormat()             sf.Alignment = StringAlignment.Center             sf.LineAlignment = StringAlignment.Center             g.DrawString(numberString, f, Brushes.Black, imageRect, sf)          End Using       End Using    End Using    RasterImage.DeleteLeadDC(hdc)    ' 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)       ' Create an OCR document       Using ocrDocument As IOcrDocument = ocrEngine.DocumentManager.CreateDocument()          ' Add this image to the document          Dim ocrPage As IOcrPage = ocrDocument.Pages.AddPage(image, Nothing)          image.Dispose()          ' Add a callback for user-defined spell checking          ocrEngine.SpellCheckManager.SetSpellCheckCallback(AddressOf MySpellCheckCallback)          ' For the spell checking to work, we need to add the zone manually as apposed to calling          ' AutoZone. So add one zone for the whole page          Dim ocrZone As New OcrZone()          ocrZone.Name = "MyZone"          ocrZone.Selected = False          ocrZone.Bounds = New LogicalRectangle(imageRect)          ocrZone.ZoneType = OcrZoneType.Text          ocrZone.FillMethod = OcrZoneFillMethod.Default          ocrZone.RecognitionModule = OcrZoneRecognitionModule.Auto          ocrZone.CharacterFilters = OcrZoneCharacterFilters.None          ocrZone.UserDictionarySectionName = Nothing          ocrZone.RecognitionOptions = OcrZoneRecognitionOptions.None          ' Add the zone, this will use our spell check callback since we set it before          ocrPage.Zones.Add(ocrZone)          ' Recognize this page          Dim text As String = ocrPage.RecognizeText(Nothing)          Console.WriteLine("Recognition results\n--------------\n{0}", text)       End Using       ' Shutdown the engine       ' Note: calling Dispose will also automatically shutdown the engine if it has been started       ocrEngine.Shutdown()    End Using End Sub Private Function MySpellCheckCallback(ByVal engine As IOcrEngine, ByVal page As IOcrPage, ByVal zoneIndex As Integer, ByVal recognizedValue As String) As OcrSpellCheckOpinion    Dim pageIndex As Integer = page.Document.Pages.IndexOf(page)    Console.WriteLine("Checking (Page: {0}/Zone: {1}): {2}", pageIndex, zoneIndex, recognizedValue)    ' See if the text contains digits only    Dim result As Integer    If (Integer.TryParse(recognizedValue, result)) Then       Return OcrSpellCheckOpinion.Sure    Else       Return OcrSpellCheckOpinion.Impossible    End If End Function

C#

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public void OcrSpellCheckWordCallbackExample()  {     // 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");     // Create an image with misspelled number     string numberString = "123!4";       RasterImage image = new RasterImage(RasterMemoryFlags.Conventional, 320, 200, 1, RasterByteOrder.Bgr, RasterViewPerspective.TopLeft, null, IntPtr.Zero, 0);     Rectangle imageRect = new Rectangle(0, 0, image.ImageWidth, image.ImageHeight);       IntPtr hdc = image.CreateLeadDC();     using(Graphics g = Graphics.FromHdc(hdc))     {        g.FillRectangle(Brushes.White, imageRect);          using(Font f = new Font("Arial", 60, FontStyle.Regular))        {           using(StringFormat sf = new StringFormat())           {              sf.Alignment = StringAlignment.Center;              sf.LineAlignment = StringAlignment.Center;              g.DrawString(numberString, f, Brushes.Black, imageRect, sf);           }        }     }       RasterImage.DeleteLeadDC(hdc);       // 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);          // Create an OCR document        using(IOcrDocument ocrDocument = ocrEngine.DocumentManager.CreateDocument())        {           // Add this image to the document           IOcrPage ocrPage = ocrDocument.Pages.AddPage(image, null);           image.Dispose();             // Add a callback for user-defined spell checking           ocrEngine.SpellCheckManager.SetSpellCheckCallback(new OcrSpellCheckCallback(MySpellCheckCallback));             // For the spell checking to work, we need to add the zone manually as apposed to calling           // AutoZone. So add one zone for the whole page           OcrZone ocrZone = new OcrZone();           ocrZone.Name = "MyZone";           ocrZone.Selected = false;           ocrZone.Bounds = new LogicalRectangle(imageRect);           ocrZone.ZoneType = OcrZoneType.Text;           ocrZone.FillMethod = OcrZoneFillMethod.Default;           ocrZone.RecognitionModule = OcrZoneRecognitionModule.Auto;           ocrZone.CharacterFilters = OcrZoneCharacterFilters.None;           ocrZone.UserDictionarySectionName = null;           ocrZone.RecognitionOptions = OcrZoneRecognitionOptions.None;             // Add the zone, this will use our spell check callback since we set it before           ocrPage.Zones.Add(ocrZone);             // Recognize this page and get the text           string text = ocrPage.RecognizeText(null);             Console.WriteLine("Recognition results\n--------------\n{0}", text);        }          // Shutdown the engine        // Note: calling Dispose will also automatically shutdown the engine if it has been started        ocrEngine.Shutdown();     }  }    private OcrSpellCheckOpinion MySpellCheckCallback(IOcrEngine engine, IOcrPage page, int zoneIndex, string recognizedValue)  {     int pageIndex = page.Document.Pages.IndexOf(page);     Console.WriteLine("Checking (Page: {0}/Zone: {1}): {2}", pageIndex, zoneIndex, recognizedValue);       // See if the text contains digits only     int result;     if(int.TryParse(recognizedValue, out result))        return OcrSpellCheckOpinion.Sure;     else        return OcrSpellCheckOpinion.Impossible;  }

You can set the OcrSpellCheckCallback to be used globally in the engine through the IOcrSpellCheckManager.SetSpellCheckCallback method.

The callback will only work with zones added manually by the user. The zones automatically found by the engine through IOcrPage.AutoZone will not cause the callback to be called.

This callback allows the user intervention in the spell checking process. The callback is called by the checking subsystem of the engine during the recognition operation. The user can then influence the decision about the recognized result through the returned OcrSpellCheckOpinion value.

For an example, if the particular zone in the page to be recognized is allowed to contain digits and only certain values are allowed. The user can return the following values:

• If the value contains digits only and falls in the range of the values allowed, the user should return OcrSpellCheckOpinion.Sure
• If the value fails to to fulfill any of the above two requirements, the user should return OcrSpellCheckOpinion.Impossible

If the particular zone in the page to be recognized is allowed to have digits only by no further restrictions, the user can return the following values:

• If the value is digits only, the user should return OcrSpellCheckOpinion.Possible
• If the value contains digits plus punctuation (for example, a comma or a period), the user should return OcrSpellCheckOpinion.Unlikely

Note: User-defined checking through the OcrSpellCheckCallback callback is not supported when using the LEADTOOLS OCR Advantage Engine.

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

Reference