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AddPage(Stream,OcrProgressCallback) Method

Summary

Adds a page from a disk file.

Syntax

C#
VB
Java
Objective-C
C++
public IOcrPage AddPage( 
   Stream stream, 
   OcrProgressCallback callback 
) 

Overloads Function AddPage( _ 
   ByVal stream As Stream, _ 
   ByVal callback As OcrProgressCallback _ 
) As IOcrPage 

- (nullable LTOcrPage *)addPageWithStream:(LTLeadStream *)stream  
                                    error:(NSError **)error 

public OcrPage addPage(ILeadStream stream, 
                       OcrProgressListener callback) 

Parameters

stream
A .NET stream containing the image.

callback
Optional callback to show operation progress.

Return Value

The IOcrPage object that define the newly added page.

Remarks

This method will load the first page from a raster image stored inside a .NET stream and adds it to the OCR document.

To add all or specific range of the pages of a multi-page image file stored in a .NET stream to the OCR document, use the AddPages(Stream stream, int imageFirstPageNumber, int imageLastPageNumber, OcrProgressCallback callback) method.

This method will add the page to the end of the collection if you already have pages in this IOcrPageCollection.

If you passed a RasterCodecs object to the IOcrEngine.Startup, then this method will use the same RasterCodecs object to load the raster image file. If you did not pass a RasterCodecs object, the engine will create an instance the first time one of the add or export page methods is called.

The image file in stream can be any of the file formats supported by LEADTOOLS. For more information, refer to Summary of All Supported Image File Formats.

You can use the OcrProgressCallback to show the operation progress or to abort it. For more information and an example, refer to OcrProgressCallback.

The LEADTOOLS OCR engine supports pages of dots per inch (DPI) values of 150 and greater. If you try to add a page with a DPI of less than 150 then the engine might be able to recognize any data from this page.

Note: The value of the "Recognition.ShareOriginalImage" (only supported by the LEADTOOLS OCR Module - LEAD Engine) setting is not used when calling this method. The engine loads the image(s) and sets them in the pages internally. The original image reference can be obtained from the page using IOcrPage.GetRasterImage(OcrPageType.Original). Sharing the original image minimizes the memory used during OCR operations.

This member only works with memory-based documents and will throw an exception otherwise. For more information, refer to IOcrDocumentManager.CreateDocument and Programming with the LEADTOOLS .NET OCR.

Example

This example will add a raster image stored in a memory stream to the OCR engine.

C#
VB
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Ocr; 
using Leadtools.Document.Writer; 
using Leadtools.Forms.Common; 
using Leadtools.ImageProcessing.Core; 
 
public void AddPageFromStreamExample() 
{ 
   string tifFileName = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.tif"); 
   string pdfFileName = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.pdf"); 
 
   // Load the TIF image into a memory stream 
   MemoryStream ms = new MemoryStream(); 
 
   using (FileStream fs = File.OpenRead(tifFileName)) 
   { 
      const int bufferSize = 1024 * 4; 
      byte[] buffer = new byte[bufferSize]; 
      int bytes = 0; 
      do 
      { 
         bytes = fs.Read(buffer, 0, bufferSize); 
         if (bytes > 0) 
            ms.Write(buffer, 0, bytes); 
      } 
      while (bytes > 0); 
   } 
 
   // Reset the stream position 
   ms.Position = 0; 
 
   // Create an instance of the engine 
   using (IOcrEngine ocrEngine = OcrEngineManager.CreateEngine(OcrEngineType.LEAD, false)) 
   { 
      // Start the engine using default parameters 
      ocrEngine.Startup(null, null, null, LEAD_VARS.OcrLEADRuntimeDir); 
 
      // Create an OCR document 
      using (IOcrDocument ocrDocument = ocrEngine.DocumentManager.CreateDocument()) 
      { 
         // Add the image 
         ocrDocument.Pages.AddPage(ms, null); 
 
         // We do not need the stream anymore 
         ms.Dispose(); 
 
         // Recognize 
         ocrDocument.Pages.Recognize(null); 
 
         // Save 
         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(); 
   } 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images"; 
   public const string OcrLEADRuntimeDir = @"C:\LEADTOOLS 20\Bin\Common\OcrLEADRuntime"; 
} 

Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.Ocr 
Imports Leadtools.Document.Writer 
Imports Leadtools.Forms 
Imports Leadtools.ImageProcessing.Core 
 
Public Sub AddPageFromStreamExample() 
   Dim tifFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.tif") 
   Dim pdfFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.pdf") 
 
   ' Load the TIF image into a memory stream 
   Dim ms As New MemoryStream() 
 
   Using fs As FileStream = File.OpenRead(tifFileName) 
      Const bufferSize As Integer = 1024 * 4 
      Dim buffer As Byte() = New Byte(bufferSize - 1) {} 
      Dim bytes As Integer = 0 
      Do 
         bytes = fs.Read(buffer, 0, bufferSize) 
         If bytes > 0 Then 
            ms.Write(buffer, 0, bytes) 
         End If 
      Loop While bytes > 0 
   End Using 
 
   ' Reset the stream position 
   ms.Position = 0 
 
   ' Create an instance of the engine 
   Using ocrEngine As IOcrEngine = OcrEngineManager.CreateEngine(OcrEngineType.LEAD, False) 
      ' Start the engine using default parameters 
      ocrEngine.Startup(Nothing, Nothing, Nothing, LEAD_VARS.OcrLEADRuntimeDir) 
 
      ' Create an OCR document 
      Using ocrDocument As IOcrDocument = ocrEngine.DocumentManager.CreateDocument() 
         ' Add the image 
         ocrDocument.Pages.AddPage(ms, Nothing) 
 
         ' We do not need the stream anymore 
         ms.Dispose() 
 
         ' Recognize 
         ocrDocument.Pages.Recognize(Nothing) 
 
         ' Save 
         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 
End Sub 
 
Public NotInheritable Class LEAD_VARS 
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images" 
   Public Const OcrLEADRuntimeDir As String = "C:\LEADTOOLS 20\Bin\Common\OcrLEADRuntime" 
End Class 

Requirements

Target Platforms

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Leadtools.Ocr Assembly