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RunJob Method

Summary

Runs a job

Syntax

C#
VB
Java
Objective-C
C++
- (LTOcrAutoRecognizeManagerJobStatus)runJob:(LTOcrAutoRecognizeJob *)job error:(NSError **)error 
public OcrAutoRecognizeManagerJobStatus runJob(OcrAutoRecognizeJob job) 

Parameters

job
The IOcrAutoRecognizeJob to run this parameter cannot be null (Nothing in VB). Use CreateJob to create a job.

Return Value

An OcrAutoRecognizeManagerJobStatus enumeration member that determines whether the job was completed successfully or aborted due to errors or user action.

Remarks

If you call this method from the same thread that created IOcrAutoRecognizeManager, then the current thread will block till this method returns. To run a job asynchronously, use RunJobAsync.

When this method returns, the IOcrAutoRecognizeJob.Errors member of job will contain any errors that might have occurred during the recognition process.

To use this method, initialize a new OcrAutoRecognizeJobData object with the job's parameters (input image file name, pages, output document format, output document name, optional zones file name, etc.), then use CreateJob to create the IOcrAutoRecognizeJob object passed as job to this method. Finally, call RunJob passing the IOcrAutoRecognizeJob object.

This method will perform the following operations:

  1. The JobStarted event is triggered.

  2. Creates one or more IOcrDocument object to store the pages into. The number of OCR documents created is dependent on MaximumThreadsPerJob. If this value is 0 (maximum CPUs/cores) or is greater than 1 and multiple threads is supported by this engine, then more than one document might be created to participate in the recognition process. The document will be created as disk-based.

  3. Loops through the pages specified in OcrAutoRecognizeJobData.FirstPageNumber and in OcrAutoRecognizeJobData.LastPageNumber in OcrAutoRecognizeJobData.ImageFileName or OcrAutoRecognizeJobData.ImageStream and for each page:

  4. When all pages are processed they are saved to result file name specified in OcrAutoRecognizeJobData.DocumentFileName using the format specified OcrAutoRecognizeJobData.Format If LTD was used, the temporary file is converted to the final document using DocumentWriter.Convert and optionally DocumentWriter.AppendLtd.

  5. All OCR documents and temporary files are deleted.

  6. The JobCompleted event is triggered.

  7. You can use the JobProgress event to show the operation progress or to abort it if threading is not used. For more information and an example, refer to OcrProgressCallback.

  8. You can use the JobOperation event to get information regarding the current operation being performed. For more information and an example, refer to JobOperation.

The IOcrAutoRecognizeManager interface also has the following options to use with this method:

Option Description
MaximumPagesBeforeLtd

Add support for converting a document with unlimited number of pages. An OCR recognition operation on a document that contains a large amount of pages (10 and more) might result in an out of memory error.

All of the LEADTOOLS OCR engines supports saving the intermediate recognition results to a temporary LTD file (DocumentFormat.LTD). The result of subsequent pages will be appended to this temporary file. When all the pages of the document have been recognized, the engine will convert the temporary LTD file to the desired output format.

The MaximumPagesBeforeLtd property defines the maximum number of pages processed as a whole. For example, if the original document has 20 pages and the value of this property is 8, the engine will recognize the first 8 pages and saves the result to a temporary file, recognizes the second 8 pages and append the results, and finally, recognize the last 4 pages and convert the temporary document to the final format.

PreprocessPageCommands

Holds an array of OcrAutoPreprocessPageCommand items to control what auto-preprocess operation to perform on each page document prior to recognition.

MaximumThreadsPerJob

Maximum number of threads to use per job. You can instruct IOcrAutoRecognizeManager to use all available machine CPUs/cores when recognizing a document. This will greatly reduce the time required to finish the OCR operation.

JobErrorMode

Ability to resume on none critical errors. For example, if a source document has a page that could not be recognized. The offending page will be added to the final document as a graphics images and recognition will continue to the next page.

JobStarted, JobProgress, JobOperation and JobCompleted events

Events to track when both synchronous and asynchronous jobs has started, being run and completed.

AbortAllJobs

Aborts all running and pending jobs.

EnableTrace

Output debug messages to the standard .NET trace listeners.

Example

This example will OCR all the images in a given folder and convert them to PDF documents. It uses multiple threads to maximize the recognition performance, supports abortion and continues on non-critical errors. This example supports converting images of any number of pages.

C#
VB
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Ocr; 
using Leadtools.Document.Writer; 
using Leadtools.Forms.Common; 
using Leadtools.WinForms; 
 
public class RunJobExample 
{ 
   // Number of documents that are pending 
   private int _documentsPending; 
   // Event to trigger when all documents are finished 
   private AutoResetEvent _allDocumentsFinishedEvent; 
 
      public void Start() 
   { 
      string imagesDirectory = LEAD_VARS.ImagesDir; 
      string documentsDirectory = Path.Combine(LEAD_VARS.ImagesDir, "RunJobExample"); 
 
      // Create the output (documents) directory 
      if (!Directory.Exists(documentsDirectory)) 
      { 
         Directory.CreateDirectory(documentsDirectory); 
      } 
 
      // Get all TIF files in input (images) directory 
      string[] imageFileNames = Directory.GetFiles(imagesDirectory, "*.tif"); 
      if (imageFileNames.Length == 0) 
      { 
         Console.WriteLine("No images to OCR"); 
         return; 
      } 
 
      // Create a new OCR engine instance 
      OcrEngineType engineType = OcrEngineType.LEAD; 
      Console.WriteLine(string.Format("Starting up {0} engine", engineType)); 
      using (IOcrEngine ocrEngine = OcrEngineManager.CreateEngine(engineType, false)) 
      { 
         ocrEngine.Startup(null, null, null, LEAD_VARS.OcrLEADRuntimeDir); 
 
         // Setup document PDF save options: Image/Text with CCITT G4 encoding for B/W 
         DocumentWriter docWriter = ocrEngine.DocumentWriterInstance; 
         PdfDocumentOptions pdfOptions = docWriter.GetOptions(DocumentFormat.Pdf) as PdfDocumentOptions; 
         pdfOptions.ImageOverText = true; 
         pdfOptions.DocumentType = PdfDocumentType.Pdf; 
         pdfOptions.FontEmbedMode = DocumentFontEmbedMode.None; 
         pdfOptions.OneBitImageCompression = OneBitImageCompressionType.FaxG4; 
         docWriter.SetOptions(DocumentFormat.Pdf, pdfOptions); 
 
         // We are going to use multiple-threads, so disable threading in 
         // IOcrAutoRecognizeManager 
         IOcrAutoRecognizeManager autoRecognizeManager = ocrEngine.AutoRecognizeManager; 
         autoRecognizeManager.MaximumThreadsPerJob = 1; 
 
         // Tell the recognize manager to continue on errors 
         autoRecognizeManager.JobErrorMode = OcrAutoRecognizeManagerJobErrorMode.Continue; 
 
         // Instead of using events to trigger when documents are done, 
         // we will use the JobCompleted events of IOcrAutoRecognizeManager 
         // to decrement a counter and trigger one event when the counter reaches 0 
         autoRecognizeManager.JobStarted += new EventHandler<OcrAutoRecognizeRunJobEventArgs>(autoRecognizeManager_JobStarted); 
         autoRecognizeManager.JobCompleted += new EventHandler<OcrAutoRecognizeRunJobEventArgs>(autoRecognizeManager_JobCompleted); 
 
         int count = imageFileNames.Length; 
         _documentsPending = count; 
         _allDocumentsFinishedEvent = new AutoResetEvent(false); 
 
         for (int i = 0; i < count; i++) 
         { 
            // Create the job data 
            string imageFileName = imageFileNames[i]; 
            string name = "Document " + (i + 1).ToString(); 
            Console.WriteLine("Queuing {0} file {1}", name, imageFileName); 
 
            JobData data = new JobData(); 
            data.AutoRecognizeManager = autoRecognizeManager; 
            data.ImageFileName = imageFileName; 
            data.DocumentFileName = Path.Combine(documentsDirectory, Path.GetFileNameWithoutExtension(imageFileName) + ".pdf"); 
            data.JobName = name; 
 
            // Queue this job 
            ThreadPool.QueueUserWorkItem(new WaitCallback(RunJob), data); 
         } 
 
         // Wait for all documents to finish 
         _allDocumentsFinishedEvent.WaitOne(); 
         _allDocumentsFinishedEvent.Close(); 
 
         autoRecognizeManager.JobStarted -= new EventHandler<OcrAutoRecognizeRunJobEventArgs>(autoRecognizeManager_JobStarted); 
         autoRecognizeManager.JobCompleted -= new EventHandler<OcrAutoRecognizeRunJobEventArgs>(autoRecognizeManager_JobCompleted); 
 
         Console.WriteLine("All documents finished, check the result files in {0}", documentsDirectory); 
      } 
   } 
   private void autoRecognizeManager_JobStarted(object sender, OcrAutoRecognizeRunJobEventArgs e) 
   { 
      // This is not strictly needed in this example, we will 
      // use it to show information 
      Console.WriteLine("{0} started...", e.Job.JobData.JobName); 
 
      // Check if we need to abort 
      if (AbortJobs(e.Job)) 
      { 
         // Yes, abort all jobs 
         e.Job.AutoRecognizeManager.AbortAllJobs(); 
      } 
   } 
 
   private void autoRecognizeManager_JobCompleted(object sender, OcrAutoRecognizeRunJobEventArgs e) 
   { 
      string message = string.Format("{0} completed ", e.Job.JobData.JobName); 
 
      IOcrAutoRecognizeJob job = e.Job; 
 
      // Show any errors 
      if (job.Errors.Count == 0) 
      { 
         message += "successfully..."; 
      } 
      else 
      { 
         message += "with errors, first error is " + job.Errors[0].Exception.Message; 
 
         // And save the errors to a text file in the document directory 
         string documentFileName = job.JobData.DocumentFileName; 
         string textPathName = Path.Combine(Path.GetDirectoryName(documentFileName), Path.GetFileNameWithoutExtension(documentFileName) + "_errors.txt"); 
         using (StreamWriter writer = File.CreateText(textPathName)) 
         { 
            writer.WriteLine(job.JobData.JobName); 
            writer.WriteLine("Data:"); 
            writer.WriteLine(" Image file name: " + job.JobData.ImageFileName); 
            writer.WriteLine(" First page number: " + job.JobData.FirstPageNumber); 
            writer.WriteLine(" Last page number: " + job.JobData.LastPageNumber); 
            writer.WriteLine(" Format:" + job.JobData.Format); 
            writer.WriteLine(" Document file name: " + job.JobData.DocumentFileName); 
            writer.WriteLine("Errors:"); 
 
            foreach (OcrAutoRecognizeManagerJobError error in job.Errors) 
            { 
               writer.WriteLine(" Page: {0} during {1}. Error: {2}", error.ImagePageNumber, error.Operation, error.Exception.Message); 
            } 
         } 
      } 
 
      Console.WriteLine(message); 
 
      // Decrement the documents count, when we reach 0, we are done 
      // Since this will be called from multiple threads, we need 
      // to use a thread-safety procedure 
      int pending = Interlocked.Decrement(ref _documentsPending); 
 
      // If we are the last document, wait up main thread 
      if (pending == 0) 
      { 
         _allDocumentsFinishedEvent.Set(); 
      } 
   } 
 
   private class JobData 
   { 
      public IOcrAutoRecognizeManager AutoRecognizeManager; 
      public string ImageFileName; 
      public string DocumentFileName; 
      public string JobName; 
   } 
 
   private void RunJob(object state) 
   { 
      JobData data = state as JobData; 
 
      Console.WriteLine("Running {0}", data.JobName); 
 
      // Run it 
      OcrAutoRecognizeJobData jobData = new OcrAutoRecognizeJobData(data.ImageFileName, DocumentFormat.Pdf, data.DocumentFileName); 
      jobData.JobName = data.JobName; 
      IOcrAutoRecognizeJob job = data.AutoRecognizeManager.CreateJob(jobData); 
      data.AutoRecognizeManager.RunJob(job); 
   } 
 
   private bool AbortJobs(IOcrAutoRecognizeJob ocrJob) 
   { 
      // In your application, you can check if abortion is required, for example, if the user 
      // has pressed the Cancel button on a progress bar or if your service is shutting down. 
 
      // In this example, we will never abort, but you can change this code to return true 
      // upon any condition (or when a specific job is about to start) 
      // and the engine will abort all current and pending jobs 
      return false; 
   } 
} 
 
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.Common 
Imports Leadtools.WinForms 
 
Public Class RunJobExample 
   ' Number of documents that are pending 
   Private _documentsPending As Integer 
   ' Event to trigger when all documents are finished 
   Private _allDocumentsFinishedEvent As AutoResetEvent 
 
   Public Sub Start() 
      Dim imagesDirectory As String = LEAD_VARS.ImagesDir 
      Dim documentsDirectory As String = Path.Combine(LEAD_VARS.ImagesDir, "RunJobExample") 
 
      ' Create the output (documents) directory 
      If Not Directory.Exists(documentsDirectory) Then 
         Directory.CreateDirectory(documentsDirectory) 
      End If 
 
      ' Get all TIF files in input (images) directory 
      Dim imageFileNames As String() = Directory.GetFiles(imagesDirectory, "*.tif") 
      If imageFileNames.Length = 0 Then 
         Console.WriteLine("No images to OCR") 
         Return 
      End If 
 
      ' Create a new OCR engine instance 
      Dim engineType As OcrEngineType = OcrEngineType.LEAD 
      Console.WriteLine(String.Format("Starting up {0} engine", engineType)) 
      Using ocrEngine As IOcrEngine = OcrEngineManager.CreateEngine(engineType, False) 
         ocrEngine.Startup(Nothing, Nothing, Nothing, LEAD_VARS.OcrLEADRuntimeDir) 
 
         ' Setup document PDF save options: Image/Text with CCITT G4 encoding for B/W 
         Dim docWriter As DocumentWriter = ocrEngine.DocumentWriterInstance 
         Dim pdfOptions As PdfDocumentOptions = TryCast(docWriter.GetOptions(DocumentFormat.Pdf), PdfDocumentOptions) 
         pdfOptions.ImageOverText = True 
         pdfOptions.DocumentType = PdfDocumentType.Pdf 
         pdfOptions.FontEmbedMode = DocumentFontEmbedMode.None 
         pdfOptions.OneBitImageCompression = OneBitImageCompressionType.FaxG4 
         docWriter.SetOptions(DocumentFormat.Pdf, pdfOptions) 
 
         ' We are going to use multiple-threads, so disable threading in 
         ' IOcrAutoRecognizeManager 
         Dim autoRecognizeManager As IOcrAutoRecognizeManager = ocrEngine.AutoRecognizeManager 
         autoRecognizeManager.MaximumThreadsPerJob = 1 
 
         ' Tell the recognize manager to continue on errors 
         autoRecognizeManager.JobErrorMode = OcrAutoRecognizeManagerJobErrorMode.[Continue] 
 
         ' Instead of using events to trigger when documents are done, 
         ' we will use the JobCompleted events of IOcrAutoRecognizeManager 
         ' to decrement a counter and trigger one event when the counter reaches 0 
         AddHandler autoRecognizeManager.JobStarted, AddressOf autoRecognizeManager_JobStarted 
         AddHandler autoRecognizeManager.JobCompleted, AddressOf autoRecognizeManager_JobCompleted 
 
         Dim count As Integer = imageFileNames.Length 
         _documentsPending = count 
         _allDocumentsFinishedEvent = New AutoResetEvent(False) 
 
         For i As Integer = 0 To count - 1 
            ' Create the job data 
            Dim imageFileName As String = imageFileNames(i) 
            Dim name As String = "Document " & (i + 1).ToString() 
            Console.WriteLine("Queuing {0} file {1}", name, imageFileName) 
 
            Dim data As New JobData() 
            data.AutoRecognizeManager = autoRecognizeManager 
            data.ImageFileName = imageFileName 
            data.DocumentFileName = Path.Combine(documentsDirectory, Path.GetFileNameWithoutExtension(imageFileName) & ".pdf") 
            data.JobName = name 
 
            ' Queue this job 
            ThreadPool.QueueUserWorkItem(New WaitCallback(AddressOf RunJob), data) 
         Next 
 
         ' Wait for all documents to finish 
         _allDocumentsFinishedEvent.WaitOne() 
         _allDocumentsFinishedEvent.Close() 
 
         RemoveHandler autoRecognizeManager.JobStarted, AddressOf autoRecognizeManager_JobStarted 
         RemoveHandler autoRecognizeManager.JobCompleted, AddressOf autoRecognizeManager_JobCompleted 
 
         Console.WriteLine("All documents finished, check the result files in {0}", documentsDirectory) 
      End Using 
   End Sub 
 
   Private Sub autoRecognizeManager_JobStarted(sender As Object, e As OcrAutoRecognizeRunJobEventArgs) 
      ' This is not strictly needed in this example, we will 
      ' use it to show information 
      Console.WriteLine("{0} started...", e.Job.JobData.JobName) 
 
      ' Check if we need to abort 
      If AbortJobs(e.Job) Then 
         ' Yes, abort all jobs 
         e.Job.AutoRecognizeManager.AbortAllJobs() 
      End If 
   End Sub 
 
   Private Sub autoRecognizeManager_JobCompleted(sender As Object, e As OcrAutoRecognizeRunJobEventArgs) 
      Dim message As String = String.Format("{0} completed ", e.Job.JobData.JobName) 
 
      Dim job As IOcrAutoRecognizeJob = e.Job 
 
      ' Show any errors 
      If job.Errors.Count = 0 Then 
         message += "successfully..." 
      Else 
         message += "with errors, first error is " + job.Errors(0).Exception.Message 
 
         ' And save the errors to a text file in the document directory 
         Dim documentFileName As String = job.JobData.DocumentFileName 
         Dim textPathName As String = 
            Path.Combine(Path.GetDirectoryName(documentFileName), Path.GetFileNameWithoutExtension(documentFileName) & "_errors.txt") 
 
         Using writer As StreamWriter = File.CreateText(textPathName) 
            writer.WriteLine(job.JobData.JobName) 
            writer.WriteLine("Data:") 
            writer.WriteLine(" Image file name: " & job.JobData.ImageFileName) 
            writer.WriteLine(" First page number: " & job.JobData.FirstPageNumber) 
            writer.WriteLine(" Last page number: " & job.JobData.LastPageNumber) 
            writer.WriteLine(" Format:" & job.JobData.Format) 
            writer.WriteLine(" Document file name: " & job.JobData.DocumentFileName) 
            writer.WriteLine("Errors:") 
 
            For Each [error] As OcrAutoRecognizeManagerJobError In job.Errors 
               writer.WriteLine(" Page: {0} during {1}. Error: {2}", [error].ImagePageNumber, [error].Operation, [error].Exception.Message) 
            Next 
         End Using 
      End If 
 
      Console.WriteLine(message) 
 
      ' Decrement the documents count, when we reach 0, we are done 
      ' Since this will be called from multiple threads, we need 
      ' to use a thread-safety procedure 
      Dim pending As Integer = Interlocked.Decrement(_documentsPending) 
 
      ' If we are the last document, wait up main thread 
      If pending = 0 Then 
         _allDocumentsFinishedEvent.Set() 
      End If 
   End Sub 
 
   Private Class JobData 
      Public AutoRecognizeManager As IOcrAutoRecognizeManager 
      Public ImageFileName As String 
      Public DocumentFileName As String 
      Public JobName As String 
   End Class 
 
   Private Sub RunJob(state As Object) 
      Dim data As JobData = TryCast(state, JobData) 
 
      Console.WriteLine("Running {0}", data.JobName) 
 
      ' Run it 
      Dim jobData As New OcrAutoRecognizeJobData(data.ImageFileName, DocumentFormat.Pdf, data.DocumentFileName) 
      jobData.JobName = data.JobName 
      Dim job As IOcrAutoRecognizeJob = data.AutoRecognizeManager.CreateJob(jobData) 
      data.AutoRecognizeManager.RunJob(job) 
   End Sub 
 
   Private Function AbortJobs(ocrJob As IOcrAutoRecognizeJob) As Boolean 
      ' In your application, you can check if abortion is required, for example, if the user 
      ' has pressed the Cancel button on a progress bar or if your service is shutting down. 
 
      ' In this example, we will never abort, but you can change this code to return true 
      ' upon any condition (or when a specific job is about to start) 
      ' and the engine will abort all current and pending jobs 
      Return False 
   End Function 
End Class 
 
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