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Startup Method

Summary

Starts the OCR engine.

Syntax

C#
VB
Java
Objective-C
WinRT C#
C++
- (BOOL)startup:(nullable LTRasterCodecs *)rasterCodecs  
 documentWriter:(nullable LTDocumentWriter *)documentWriter  
  workDirectory:(nullable NSString *)workDirectory  
engineDirectory:(nullable NSString *)engineDirectory  
          error:(NSError **)error 
             
public void startup(RasterCodecs rasterCodecs, 
                    String workDirectory, 
                    String startupParameters, 
                    String sharedLibsFolder) 
             
function Leadtools.Forms.Ocr.IOcrEngine.Startup(  
   rasterCodecs , 
   documentWriter , 
   workDirectory , 
   startupParameters  
) 

Parameters

rasterCodecs
Optional instance of a RasterCodecs object to be used when loading image files from disk inside the engine. You can pass your own initialized instance of RasterCodecs to be used. The same object will then be used internally by the OCR engine when loading raster image files. Otherwise, pass null (Nothing in VB) and the IOcrEngine will create and use its own version of RasterCodecs when needed. Refer to RasterCodecsInstance for more information on how this parameter is used by the OCR engine during its lifetime, refer to OCR Engine and RasterCodecs/DocumentWriter Usage.

documentWriter
Optional instance of a DocumentWriter object to be used when saving OCR documents to disk inside the engine. You can pass your own initialized instance of DocumentWriter to be used. The same object will then be used internally by the OCR engine when saving OCR documents to disk. Otherwise, pass null (Nothing in VB) and the IOcrEngine will create and use its own version of DocumentWriter when needed. Refer to DocumentWriterInstance for more information on how this parameter is used by the OCR engine during its lifetime, refer to OCR Engine and RasterCodecs/DocumentWriter Usage.

workDirectory
Optional path to a directory to be used when the engine saves temporary files. The IOcrEngine object will create various temporary files during recognition and document saving processes. It will use the path passed in workDirectory as the location where these temporary files will be created. You can pass null (Nothing in VB) to let the engine select the temporary directory of the current logged in user (TEMP).

In either case, the value of working directory of the current started IOcrEngine can be obtained through the WorkDirectory property.

The engine automatically deletes any temporary files created. However, if an unexpected error occurs (for example, an unhandled exception), some temporary files may still reside in the work directory after the application exits. A typical application may use a custom directory inside the application path and manually deletes any files that may reside there before calling Startup in case the previous instance of the application exited abnormally.

If the value of the workDirectory parameter is not null (Nothing in VB), then it must refer to a valid directory that exists in the system and the process that created the engine must have enough access rights to read, write and delete files from this directory.

startupParameters
Optional startup parameter. The value of this parameter depends on the type of this IOcrEngine as follows:

Engine startupParameters
OcrEngineType.Advantage The path to the folder containing the OCR engine files. If you pass null (Nothing in VB) to startupParameters, then the LEADTOOLS OCR engine will look for these extra files in the default installation folder specified above. When you are ready to package your application, you might want to change the location where the LEADTOOLS OCR engine looks for these extra files. You can use this property to do that. Set the path you want before calling the Startup method.
OcrEngineType.Arabic The path to the folder containing the OCR engine files. If you pass null (Nothing in VB) to startupParameters, then the LEADTOOLS OCR engine will look for these extra files in the default installation folder specified above. When you are ready to package your application, you might want to change the location where the LEADTOOLS OCR engine looks for these extra files. You can use this property to do that. Set the path you want before calling the Startup method.
OcrEngineType.Professional The path to the folder containing the OCR engine files. If you pass null (Nothing in VB) to startupParameters, then the LEADTOOLS OCR engine will look for these extra files in the default installation folder specified above. When you are ready to package your application, you might want to change the location where the LEADTOOLS OCR engine looks for these extra files. You can use this property to do that. Set the path you want before calling the Startup method.
Remarks

The Startup method must be called before invoking any other methods or properties in this IOcrEngine.

To check if the engine is started, use the IsStarted property.

You must call Shutdown to shut down the engine and free the memory and resources used.

You can call the Startup method multiple times, only the first call will start the engine while subsequent calls will only increment an internal counter. You must call Shutdown for each Startup called.

The IOcrEngine interface implements IDisposable. It is highly recommended that you call Dispose (or use the using statement in C# or Using statement in VB) when creating the IOcrEngine instance. The Dispose method will automatically shuts down the engine if it has been started.

Example

The following example assumes you copied the OCR engine runtime files to C:\MyApp\Ocr.

C#
VB
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Forms.Ocr; 
using Leadtools.Forms.DocumentWriters; 
 
public void StartupEngineExample() 
{ 
   // Use RasterCodecs to load an image file 
   // Note: You can let the engine load the image file directly as shown in the other examples 
   RasterCodecs codecs = new RasterCodecs(); 
   RasterImage image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.tif")); 
 
   // Assume you copied the engine runtime files to C:\MyApp\Ocr 
   string engineDir = @"C:\MyApp\Ocr"; 
 
   // Store the engine work directory into a path inside our application 
   string workDir = @"C:\MyApp\OcrTemp"; 
 
   // Delete all files in the work directory in case the previous version of our application exited abnormally and 
   // the engine did not get the chance to clean all of its temporary files (if any) 
   Directory.Delete(workDir, true); 
 
   // Re-create the work directory 
   Directory.CreateDirectory(workDir); 
 
   // Create an instance of the engine 
   using (IOcrEngine ocrEngine = OcrEngineManager.CreateEngine(OcrEngineType.Advantage, false)) 
   { 
      // Show that the engine has not been started yet 
      Console.WriteLine("Before calling Startup, IsStarted = " + ocrEngine.IsStarted); 
 
      // Start the engine using our parameters 
      // Since we already have a RasterCodecs object, we can re-use it to save memory and resources 
      ocrEngine.Startup(codecs, null, workDir, engineDir); 
 
      // Make sure the engine is using our working directory 
      Console.WriteLine("workDir passed is {0}, the value of WorkDirectory after Startup is {1}", workDir, ocrEngine.WorkDirectory); 
 
      // Show that the engine has started fine 
      Console.WriteLine("After calling Startup, EngineType is {0}, IsStarted = {1}", ocrEngine.EngineType, ocrEngine.IsStarted); 
 
      // Maks sure the engine is using our own version of RasterCodecs 
      Debug.Assert(codecs == ocrEngine.RasterCodecsInstance); 
 
      // Create a page from the raster image as page to the document 
      IOcrPage ocrPage = ocrEngine.CreatePage(image, OcrImageSharingMode.AutoDispose); 
      // image belongs to the page and will be dispose when the page is disposed 
 
      // Recognize the page 
      // Note, Recognize can be called without calling AutoZone or manually adding zones. The engine will 
      // check and automatically auto-zones the page 
      ocrPage.Recognize(null); 
 
      // Create a file based document 
      using (IOcrDocument ocrDocument = ocrEngine.DocumentManager.CreateDocument(null, OcrCreateDocumentOptions.AutoDeleteFile)) 
      { 
         // Add the page 
         ocrDocument.Pages.Add(ocrPage); 
         // No need for the page anymore 
         ocrPage.Dispose(); 
 
         // Save the document we have as PDF 
         string pdfFileName = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.pdf"); 
         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"; 
} 
Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.Forms.Ocr 
Imports Leadtools.Forms.DocumentWriters 
 
Public Sub StartupEngineExample() 
   ' Use RasterCodecs to load an image file 
   ' Note: You can let the engine load the image file directly as shown in the other examples 
   Dim codecs As New RasterCodecs() 
   Dim image As RasterImage = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.tif")) 
 
   ' Assume you copied the engine runtime files to C:\MyApp\Ocr 
   Dim engineDir As String = "C:\MyApp\Ocr" 
 
   ' Store the engine work directory into a path inside our application 
   Dim workDir As String = "C:\MyApp\OcrTemp" 
 
   ' Delete all files in the work directory in case the previous version of our application exited abnormally and 
   ' the engine did not get the chance to clean all of its temporary files (if any) 
   Directory.Delete(workDir, True) 
 
   ' Re-create the work directory 
   Directory.CreateDirectory(workDir) 
 
   ' Create an instance of the engine 
   Using ocrEngine As IOcrEngine = OcrEngineManager.CreateEngine(OcrEngineType.Advantage, False) 
      ' Show that the engine has not been started yet 
      Console.WriteLine("Before calling Startup, IsStarted = " & ocrEngine.IsStarted) 
 
      ' Start the engine using our parameters 
      ' Since we already have a RasterCodecs object, we can re-use it to save memory and resources 
      ocrEngine.Startup(codecs, Nothing, workDir, engineDir) 
 
      ' Make sure the engine is using our working directory 
      Console.WriteLine("workDir passed is {0}, the value of WorkDirectory after Startup is {1}", workDir, ocrEngine.WorkDirectory) 
 
      ' Show that the engine has started fine 
      Console.WriteLine("After calling Startup, EngineType is {0}, IsStarted = {1}", ocrEngine.EngineType, ocrEngine.IsStarted) 
 
      ' Maks sure the engine is using our own version of RasterCodecs 
      Debug.Assert(codecs Is ocrEngine.RasterCodecsInstance) 
 
      ' Create a page from the raster image as page to the document 
      Dim ocrPage As IOcrPage = ocrEngine.CreatePage(image, OcrImageSharingMode.AutoDispose) 
      ' image belongs to the page and will be dispose when the page is disposed 
 
      ' Recognize the page 
      ' Note, Recognize can be called without calling AutoZone or manually adding zones. The engine will 
      ' check and automatically auto-zones the page 
      ocrPage.Recognize(Nothing) 
 
      ' Create a file based document 
      Using ocrDocument As IOcrDocument = ocrEngine.DocumentManager.CreateDocument(Nothing, OcrCreateDocumentOptions.AutoDeleteFile) 
         ' Add the page 
         ocrDocument.Pages.Add(ocrPage) 
         ' No need for the page anymore 
         ocrPage.Dispose() 
 
         ' Save the document we have as PDF 
         Dim pdfFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.pdf") 
         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" 
End Class 

Requirements

Target Platforms

Help Version 19.0.2017.10.27
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Leadtools.Forms.Ocr Assembly