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AddPage(Uri,OcrProgressCallback) Method

Summary

Adds a page from a URI.

Syntax

C#
VB
C++
public IOcrPage AddPage( 
   Uri uri, 
   OcrProgressCallback callback 
) 

Overloads Function AddPage( _ 
   ByVal uri As Uri, _ 
   ByVal callback As OcrProgressCallback _ 
) As IOcrPage 

Parameters

uri
A URI containing the path to 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 in a URI and adds it to the OCR document.

The URI can point to a file in a remote HTTP server, UNC or FTP.

To add all or specific range of the pages of a multi-page image file stored in a URI to the OCR document, use the AddPages(Uri uri, 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 uri 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 an HTTP location to an OCR document.

C#
VB
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Ocr; 
using Leadtools.Document.Writer; 
using Leadtools.Forms.Common; 
using Leadtools.ImageProcessing.Core; 
 
public async void AddPageFromUriExample() 
{ 
   // Change this URI to the location of the image you want to load 
   Uri uri = new Uri(@"https://demo.leadtools.com/images/tiff/ocr1.tif"); 
   string pdfFileName = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.pdf"); 
 
   // 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()) 
      { 
         using (var codecs = new RasterCodecs()) 
         { 
            using (ILeadStream leadStream = await LeadStream.Factory.FromUri(uri)) 
            { 
               RasterImage image = await codecs.LoadAsync(leadStream); 
               // Add the image 
               ocrDocument.Pages.AddPage(image, null); 
            } 
         } 
 
         // 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 Async Sub AddPageFromUriExample() 
   ' Change this URI to the location of the image you want to load 
   Dim uri As New Uri(Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.tif")) 
   Dim pdfFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.pdf") 
 
   ' 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() 
         Using codecs As RasterCodecs = New RasterCodecs() 
            Using lStream As ILeadStream = Await LeadStream.Factory.FromUri(uri) 
               Dim image As RasterImage = Await codecs.LoadAsync(lStream) 
               ' Add the image 
               ocrDocument.Pages.AddPage(image, Nothing) 
            End Using 
         End Using 
 
         ' 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

Help Version 20.0.2018.6.20
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Leadtools.Ocr Assembly