RunJob Method

Imports Leadtools
Imports Leadtools.Codecs
Imports Leadtools.Forms.Ocr
Imports Leadtools.Forms.DocumentWriters
Imports Leadtools.Forms
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 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.Advantage
      Console.WriteLine(String.Format("Starting up {0} engine", engineType))
      Using ocrEngine As IOcrEngine = OcrEngineManager.CreateEngine(engineType, False)
         ocrEngine.Startup(Nothing, Nothing, Nothing, LEAD_VARS.OcrAdvantageRuntimeDir)

         ' Setup document PDF save options: Image/Text with CCITT G4 encoding for B/W
         Dim docWriter As DocumentWriter = ocrEngine.DocumentWriterInstance
         Dim pdfOptions As PdfDocumentOptions = CType(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(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(ByVal sender As Object, ByVal 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(ByVal sender As Object, ByVal 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.ToString())
            writer.WriteLine(" Last page number: " + job.JobData.LastPageNumber.ToString())
            writer.WriteLine(" Format:" + job.JobData.Format.ToString())
            writer.WriteLine(" Document file name: " + job.JobData.DocumentFileName)
            writer.WriteLine("Errors:")

            For Each err As OcrAutoRecognizeManagerJobError In job.Errors
               writer.WriteLine(" Page: {0} during {1}. Error: {2}", err.ImagePageNumber, err.Operation, err.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(ByVal state As Object)
      Dim data As JobData = CType(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(ByVal 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

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