AddDib(IntPtr,OcrProgressCallback) Method

Adds a page from a DIB (Device-independent bitmap) stored in unmanaged memory.

Syntax

C#
Visual Basic
WinRT C#
Objective-C
Java
WinRT JavaScript
C++

IOcrPage AddDib( 
   IntPtr dib,
   OcrProgressCallback callback
)

'Declaration
 
Overloads Function AddDib( _
   ByVal dib As IntPtr, _
   ByVal callback As OcrProgressCallback _
) As IOcrPage

'Usage
 
Dim instance As IOcrPageCollection
Dim dib As IntPtr
Dim callback As OcrProgressCallback
Dim value As IOcrPage
 
value = instance.AddDib(dib, callback)

IOcrPage AddDib( 
   IntPtr dib,
   OcrProgressCallback callback
)

function Leadtools.Forms.Ocr.IOcrPageCollection.AddDib(IntPtr,OcrProgressCallback)( 
   dib ,
   callback 
)

IOcrPage^ AddDib( 
   IntPtr dib,
   OcrProgressCallback^ callback
)

Parameters

dib: An unmanaged pointer to the DIB (device-independent bitmap).
callback: Optional callback to show operation progress.

Return Value

The IOcrPage object that define the newly added page.

Remarks

This method will add a device independent bitmap (DIB) stored in an unmanaged memory pointer to the OCR document.

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

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 LEADTOOLS Plus OCR engine does not support image size greater than A3 paper size (11.7 by 16.5 inches at 300 dpi). Attempting to add an image that has a size greater than A3 will result in an error. For document of size greater than the maximum allowed, you must first resize the image before adding it to the LEADTOOLS Plus OCR engine. The Professional and Advantage engines do not have a restriction on the image size.

Note: The value of the "Recognition.ShareOriginalImage" (only supported by the Advantage OCR 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.

Example

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

Copy Code

Imports Leadtools
Imports Leadtools.Codecs
Imports Leadtools.Forms.Ocr
Imports Leadtools.Forms
Imports Leadtools.Forms.DocumentWriters
Imports Leadtools.WinForms
Imports Leadtools.ImageProcessing.Core
Imports Leadtools.Drawing

Public Sub AddPageFromDibExample()
   Dim tifFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.tif")
   Dim bmpFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.bmp")
   Dim pdfFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.pdf")
   ' Get a DIB
   ' In this example, we will save the TIF file as BMP, then load it without the BITMAPFILEHEADER structure
   ' The result is a valid Windows DIB

   Using codecs As New RasterCodecs()
      codecs.Convert(tifFileName, bmpFileName, RasterImageFormat.Bmp, 0, 0, 1, Nothing)
   End Using

   ' From MSDN
   Dim bitmapFileHeaderStructSize As Integer = 14
   Dim dib As IntPtr = IntPtr.Zero

   Using fs As FileStream = File.OpenRead(bmpFileName)
      ' Allocate the DIB
      Dim dibSize As Integer = CType(fs.Length - bitmapFileHeaderStructSize, Integer)
      dib = Marshal.AllocHGlobal(dibSize)
      Dim dibOffset As Integer = 0

      ' Now read it
      fs.Seek(bitmapFileHeaderStructSize, SeekOrigin.Begin)

      Dim bufferSize As Integer = 1024 * 4
      Dim buffer(bufferSize - 1) As Byte
      Dim bytes As Integer = 0
      Do
         bytes = fs.Read(buffer, 0, bufferSize)
         If (bytes > 0) Then
            Dim dibPtr As New IntPtr(dib.ToInt64() + dibOffset)
            Marshal.Copy(buffer, 0, dibPtr, bytes)
            dibOffset += bytes
         End If

      Loop While (bytes > 0)
   End Using

   ' Create an instance of the engine
   Using ocrEngine As IOcrEngine = OcrEngineManager.CreateEngine(OcrEngineType.Advantage, False)
      ' Start the engine using default parameters
      ocrEngine.Startup(Nothing, Nothing, Nothing, LEAD_VARS.OcrAdvantageRuntimeDir)

      ' Create an OCR document
      Using ocrDocument As IOcrDocument = ocrEngine.DocumentManager.CreateDocument()
         ' Add the image
         ocrDocument.Pages.AddDib(dib, Nothing)

         ' Free the DIB since we do not need it anymore
         Marshal.FreeHGlobal(dib)

         ' 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 OcrAdvantageRuntimeDir As String = "C:\LEADTOOLS 18\Bin\Common\OcrAdvantageRuntime"
End Class

using Leadtools;
using Leadtools.Codecs;
using Leadtools.Forms.Ocr;
using Leadtools.Forms.DocumentWriters;
using Leadtools.Forms;
using Leadtools.ImageProcessing.Core;

public void AddPageFromDibExample()
{
   string tifFileName = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.tif");
   string bmpFileName = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.bmp");
   string pdfFileName = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.pdf");
   // Get a DIB
   // In this example, we will save the TIF file as BMP, then load it without the BITMAPFILEHEADER structure
   // The result is a valid Windows DIB

   using (RasterCodecs codecs = new RasterCodecs())
      codecs.Convert(tifFileName, bmpFileName, RasterImageFormat.Bmp, 0, 0, 1, null);


   // From MSDN
   const int bitmapFileHeaderStructSize = 14;
   IntPtr dib = IntPtr.Zero;

   using (FileStream fs = File.OpenRead(bmpFileName))
   {
      // Allocate the DIB
      int dibSize = (int)fs.Length - bitmapFileHeaderStructSize;
      dib = Marshal.AllocHGlobal(dibSize);
      int dibOffset = 0;

      // Now read it
      fs.Seek(bitmapFileHeaderStructSize, SeekOrigin.Begin);

      const int bufferSize = 1024 * 4;
      byte[] buffer = new byte[bufferSize];
      int bytes = 0;
      do
      {
         bytes = fs.Read(buffer, 0, bufferSize);
         if (bytes > 0)
         {
            IntPtr dibPtr = new IntPtr(dib.ToInt64() + dibOffset);
            Marshal.Copy(buffer, 0, dibPtr, bytes);
            dibOffset += bytes;
         }
      }
      while (bytes > 0);
   }

   // Create an instance of the engine
   using (IOcrEngine ocrEngine = OcrEngineManager.CreateEngine(OcrEngineType.Advantage, false))
   {
      // Start the engine using default parameters
      ocrEngine.Startup(null, null, null, LEAD_VARS.OcrAdvantageRuntimeDir);

      // Create an OCR document
      using (IOcrDocument ocrDocument = ocrEngine.DocumentManager.CreateDocument())
      {
         // Add the image
         ocrDocument.Pages.AddDib(dib, null);

         // Free the DIB since we do not need it anymore
         Marshal.FreeHGlobal(dib);

         // 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 OcrAdvantageRuntimeDir = @"C:\LEADTOOLS 18\Bin\Common\OcrAdvantageRuntime";
}

using Leadtools;
using Leadtools.Codecs;
using Leadtools.Forms.Ocr;
using Leadtools.Forms.DocumentWriters;
using Leadtools.Forms;
using Leadtools.ImageProcessing.Core;

[TestMethod]
public async Task AddPageFromDibExample()
{
   string tifFileName = @"Assets\Ocr1.tif";
   string bmpFileName = "Ocr1.bmp";
   string pdfFileName = "Ocr1.pdf";
   // Get a DIB
   // In this example, we will save the TIF file as BMP, then load it without the BITMAPFILEHEADER structure
   // The result is a valid Windows DIB
   StorageFile loadFile = await Tools.AppInstallFolder.GetFileAsync(tifFileName);
   StorageFile saveFile = await Tools.AppLocalFolder.CreateFileAsync(bmpFileName, CreationCollisionOption.ReplaceExisting);

   RasterCodecs codecs = new RasterCodecs();
   await codecs.ConvertAsync(LeadStreamFactory.Create(loadFile), LeadStreamFactory.Create(saveFile), RasterImageFormat.Bmp, 0, 0, 1, null);

   Windows.Storage.Streams.IBuffer dib;
   loadFile = await Tools.AppLocalFolder.GetFileAsync(bmpFileName);
   using (RasterImage image = await codecs.LoadAsync(LeadStreamFactory.Create(loadFile)))
   {
      dib = image.ToDib(RasterConvertToDibType.BitmapInfoHeader);
   }

   // Create an instance of the engine
   IOcrEngine ocrEngine = OcrEngineManager.CreateEngine(OcrEngineType.Advantage, false);

   // Start the engine using default parameters
   ocrEngine.Startup(null, null, String.Empty, Tools.OcrEnginePath);

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

   // Add the image
   ocrDocument.Pages.AddDib(dib, null);

   // Recognize
   ocrDocument.Pages.Recognize(null);

   // Save
   saveFile = await Tools.AppLocalFolder.CreateFileAsync(pdfFileName, CreationCollisionOption.ReplaceExisting);
   await ocrDocument.SaveAsync(LeadStreamFactory.Create(saveFile), DocumentFormat.Pdf, null);

   // Shutdown the engine
   ocrEngine.Shutdown();
}

Requirements

Target Platforms

Reference

IOcrPageCollection Interface
IOcrPageCollection Members
Overload List
OcrEngineManager Class
OcrEngineType Enumeration
IOcrPage Interface
Programming with the LEADTOOLS .NET OCR