DocumentReader Class

Visual Basic
C#
Objective-C
Java
C++

public abstract class DocumentReader : System.IDisposable

'Declaration
 
Public MustInherit Class DocumentReader 
   Implements System.IDisposable

'Usage
 
Dim instance As DocumentReader

public ref class DocumentReader abstract : public System.IDisposable

The DocumentReader class allows reading images, thumbnails, text data and metadata from any of the supported types using a uniform set of methods and properties, regardless of the document type.

The current implementation of the LEADTOOLS Document Readers support reading the following document types:

DocumentReaderType.Pdf: This is the document reader responsible for parsing PDF documents. PDF document text is parsed without the need of an OCR engine. PDF support is provided through the Leadtools.Forms.DocumentReaders.Pdf assembly.
DocumentReaderType.Xps: This is the document reader responsible for parsing XPS documents. XPS document text is parsed without the need of an OCR engine. XPS support is provided through the Leadtools.Forms.DocumentReaders.Xps assembly.
DocumentReaderType.Raster: This is the document reader responsible for parsing everything else, such as TIFF and JPEG documents. An OCR engine is required to parse the text of the document (by passing a started object of type Leadtools.Forms.Ocr.IOcrEngine to BeginParse. Raster support is provided through the Leadtools.Forms.DocumentReaders.Raster assembly.

LEADTOOLS will add more document readers and functionality in the near future for documents such as DICOM, DOC/DOCX(2007/2010), XLS/XLSX(2007/2010) and RTF. More objects types such as images, bookmarks, hyperlinks and annotations will also be added in the near future. Currently, support for these formats is provided by the Raster document reader (with text parsing supported by an external OCR engine).

DocumentReader is an abstract class and cannot be initialized directly. The derived classes to support PDF, XPS and the various other formats are internal to LEADTOOLS. Instead, get a DocumentReader object by using the DocumentReader.Create static (Shared in Visual Basic) method. This method will try to load the document in the supported readers and if successful, will return an instance of DocumentReader ready to use.

Once you obtain a valid instance of a DocumentReader object with a document loaded into it, you can use the following features:

Use the Pages property to access the pages of the document.
The MimeType property and GetProperties method can be used to obtain the metadata of the document.
The methods of the ImageManager property can be used get a raster image render or a thumbnail of any page in the document.
The methods of the ObjectManager property can be used to parse the objects found in any page in the document such as text items and font properties.

The DocumentReader class implements the System.IDisposable interface. You must call the System.IDisposable.Dispose method when the reader is no longer used.

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

Copy Code

Public Sub DocumentReaderExample()
   Dim documentFileName As String
   Using dlg As New OpenFileDialog()
      If dlg.ShowDialog() <> System.Windows.Forms.DialogResult.OK Then
         Return
      End If

      documentFileName = dlg.FileName
   End Using

   ' Load the document using default options
   Dim reader As DocumentReader = DocumentReader.Create(documentFileName, Nothing)

   ' Show the document properties
   Dim sb As New StringBuilder()
   sb.AppendFormat("Reader used: {0}\n", reader.ReaderType)
   sb.AppendFormat("Document has {0} pages\n", reader.Pages.Count)

   ' Get the properties (meta data)
   Dim props As IDictionary(Of String, String) = reader.GetProperties()
   For Each prop As KeyValuePair(Of String, String) In props
      sb.AppendFormat("{0}: {1}\n", prop.Key, prop.Value)
   Next

   MessageBox.Show(sb.ToString())

   ' Now show the pages sizes
   sb = New StringBuilder()
   For Each page As DocumentReaderPage In reader.Pages
      sb.AppendFormat("Page: {0} size: {1}\n", page.PageNumber, page.Size)
   Next
   MessageBox.Show(sb.ToString())

   ' Now loop and show the text for each page till use cancels

   ' If this is a Raster document such as TIFF or JPEG, we must use an OCR engine
   Dim ocrEngine As IOcrEngine = Nothing

   If reader.ReaderType = DocumentReaderType.Raster Then
      ocrEngine = OcrEngineManager.CreateEngine(OcrEngineType.Advantage, False)
      ocrEngine.Startup(Nothing, Nothing, Nothing, LEAD_VARS.OcrAdvantageRuntimeDir)
   End If

   reader.ObjectManager.BeginParse(ocrEngine)

   For Each page As DocumentReaderPage In reader.Pages
      ' Parse this page
      Dim pageText As DocumentPageText = reader.ObjectManager.ParsePageText(page)
      Dim text As String = pageText.BuildText()

      If MessageBox.Show(text, String.Format("Page {0} text, continue to next page?", _
                                             page.PageNumber), MessageBoxButtons.YesNo) = _
                                             System.Windows.Forms.DialogResult.No Then
         Exit For
      End If
   Next

   reader.ObjectManager.EndParse()

   If Not IsNothing(ocrEngine) Then
      ocrEngine.Dispose()
   End If

   reader.Dispose()
End Sub

public void DocumentReaderExample()
{
   string documentFileName;
   using(OpenFileDialog dlg = new OpenFileDialog())
   {
      if(dlg.ShowDialog() != DialogResult.OK)
      {
         return;
      }

      documentFileName = dlg.FileName;
   }

   // Load the document using default options
   DocumentReader reader = DocumentReader.Create(documentFileName, null);

   // Show the document properties
   StringBuilder sb = new StringBuilder();
   sb.AppendFormat("Reader used: {0}\n", reader.ReaderType);
   sb.AppendFormat("Document has {0} pages\n", reader.Pages.Count);

   // Get the properties (meta data)
   IDictionary<string, string> props = reader.GetProperties();
   foreach(KeyValuePair<string, string> prop in props)
   {
      sb.AppendFormat("{0}: {1}\n", prop.Key, prop.Value);
   }

   MessageBox.Show(sb.ToString());

   // Now show the pages sizes
   sb = new StringBuilder();
   foreach(DocumentReaderPage page in reader.Pages)
   {
      sb.AppendFormat("Page: {0} size: {1}\n", page.PageNumber, page.Size);
   }
   MessageBox.Show(sb.ToString());

   // Now loop and show the text for each page till use cancels

   // If this is a Raster document such as TIFF or JPEG, we must use an OCR engine
   IOcrEngine ocrEngine = null;

   if(reader.ReaderType == DocumentReaderType.Raster)
   {
      ocrEngine = OcrEngineManager.CreateEngine(OcrEngineType.Advantage, false);
      ocrEngine.Startup(null, null, null, LEAD_VARS.OcrAdvantageRuntimeDir);
   }

   reader.ObjectManager.BeginParse(ocrEngine);

   foreach(DocumentReaderPage page in reader.Pages)
   {
      // Parse this page
      DocumentPageText pageText = reader.ObjectManager.ParsePageText(page);
      string text = pageText.BuildText();

      if(MessageBox.Show(text, string.Format("Page {0} text, continue to next page?", page.PageNumber), MessageBoxButtons.YesNo) == DialogResult.No)
      {
         break;
      }
   }

   reader.ObjectManager.EndParse();

   if(ocrEngine != null)
   {
      ocrEngine.Dispose();
   }

   reader.Dispose();
}

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

DocumentReader Members
Leadtools.Forms.DocumentReaders Namespace