ReadBarcodes(RasterImage,LogicalRectangle,Int32,BarcodeSymbology[],BarcodeReadOptions[]) Method

'Declaration
 
Public Overloads Function ReadBarcodes( _
   ByVal image As RasterImage, _
   ByVal searchBounds As LogicalRectangle, _
   ByVal maximumBarcodes As Integer, _
   ByVal symbologies() As BarcodeSymbology, _
   ByVal options() As BarcodeReadOptions _
) As BarcodeData()

' This class holds the data we will pass to each thread
   Public Class MyThreadData
      ' This worker thread name
      Public Name As String
      ' Barcode reader instance
      Public BarcodeReaderInstance As BarcodeReader

      ' Array of options to use
      Public ReadOptions() As BarcodeReadOptions

      ' Image file containing the barcodes
      Public ImageFileName As String

      ' This will hold the barcodes found
      Public Barcodes() As BarcodeData

      ' In case of errors
      Public Err As Exception

      ' Event to notify when the thread is finished
      Public FinishedEvent As AutoResetEvent
   End Class


   Public Sub BarcodeReader_ReadBarcodeExample6()
      Dim imageFileNames() As String = PrepareImages()

      ' Create a Barcode engine
      Dim engine As New BarcodeEngine()

      ' Get the Barcode reader instance
      Dim reader As BarcodeReader = engine.Reader

      ' Get a version of all read options that support rotated barcodes
      Dim verticalBarcodeReadOptions() As BarcodeReadOptions = GetVerticalReadBarcodeOptions(reader)

      ' Synchronization events
      Dim finishedEvents(2) As AutoResetEvent

      ' Create the thread data objects
      Dim threadsData(2) As MyThreadData
      For i As Integer = 0 To threadsData.Length - 1
         finishedEvents(i) = New AutoResetEvent(False)

         threadsData(i) = New MyThreadData()
         threadsData(i).BarcodeReaderInstance = reader
         threadsData(i).ReadOptions = Nothing
         threadsData(i).FinishedEvent = finishedEvents(i)
      Next

      ' Setup the read options for the two threads
      threadsData(0).Name = "Read Default Options Thread"
      threadsData(0).ReadOptions = Nothing  ' Default, or horizontal
      threadsData(1).Name = "Read Vertical Barcodes Thread"
      threadsData(1).ReadOptions = verticalBarcodeReadOptions

      Dim totalBarcodes As New List(Of BarcodeData)()

      ' Now loop through all the images and try to read the barcodes with both threads at the same time
      For Each imageFileName As String In imageFileNames
         Console.WriteLine("Reading barcodes from {0}", imageFileName)

         For i As Integer = 0 To 1
            ' Clear the previous results (if any), set up the file name and run
            threadsData(i).Barcodes = Nothing
            threadsData(i).Err = Nothing
            threadsData(i).ImageFileName = imageFileName
            ThreadPool.QueueUserWorkItem(New WaitCallback(AddressOf ReadBarcodesInThread), threadsData(i))
         Next

         ' Wait till all the threads finishes
         WaitHandle.WaitAll(finishedEvents)

         ' Add the barcodes found to our list
         For i As Integer = 0 To 1
            If Not IsNothing(threadsData(i).Err) Then
               Console.WriteLine("{0} had error {1}", threadsData(i).Name, threadsData(i).Err)
            ElseIf Not IsNothing(threadsData(i).Barcodes) Then
               totalBarcodes.AddRange(threadsData(i).Barcodes)
            End If
         Next
      Next

      ' We are done, show the total number of barcodes read
      Console.WriteLine("Done. Total barcodes read: {0}", totalBarcodes.Count)
   End Sub

   Private Shared Sub ReadBarcodesInThread(ByVal state As Object)
      Dim threadData As MyThreadData = DirectCast(state, MyThreadData)

      Console.WriteLine("{0} is reading the barcodes", threadData.Name)

      Try
         ' Load the image
         Using codecs As New RasterCodecs()
            Using image As RasterImage = codecs.Load(threadData.ImageFileName, 0, CodecsLoadByteOrder.BgrOrGray, 1, 1)
               ' Read the barcodes using our options
               threadData.Barcodes = threadData.BarcodeReaderInstance.ReadBarcodes(image, LogicalRectangle.Empty, 0, Nothing, threadData.ReadOptions)
            End Using
         End Using

         Console.WriteLine("{0} has read {1} barcodes", threadData.Name, threadData.Barcodes.Length)
      Catch ex As Exception
         ' Return the error to main
         threadData.Err = ex
      Finally
         ' Tell main we are done
         threadData.FinishedEvent.Set()
      End Try
   End Sub

   Private Shared Function PrepareImages() As String()
      ' Create a 90 degrees rotated version of Barcode1.tif

      Dim originalImageFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Barcode1.tif")
      Dim rotatedImageFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Barcode1_Rotated90.tif")

      Using codecs As New RasterCodecs()
         Using image As RasterImage = codecs.Load(originalImageFileName, 0, CodecsLoadByteOrder.BgrOrGray, 1, 1)
            Dim rotate As New RotateCommand(90 * 100, RotateCommandFlags.Resize, RasterColor.FromKnownColor(RasterKnownColor.White))
            rotate.Run(image)

            codecs.Save(image, rotatedImageFileName, RasterImageFormat.CcittGroup4, 1)
         End Using
      End Using

      Return New String() {originalImageFileName, rotatedImageFileName}
   End Function

   Private Shared Function GetVerticalReadBarcodeOptions(ByVal reader As BarcodeReader) As BarcodeReadOptions()
      ' By default, the options read horizontal barcodes only, create an array of options capable of reading vertical barcodes

      ' Notice, we cloned the default options in reader so we will not change the original options

      Dim oneDReadOptions As OneDBarcodeReadOptions = DirectCast(reader.GetDefaultOptions(BarcodeSymbology.UPCA).Clone(), OneDBarcodeReadOptions)
      oneDReadOptions.SearchDirection = BarcodeSearchDirection.Vertical

      Dim fourStateReadOptions As FourStateBarcodeReadOptions = DirectCast(reader.GetDefaultOptions(BarcodeSymbology.USPS4State).Clone(), FourStateBarcodeReadOptions)
      fourStateReadOptions.SearchDirection = BarcodeSearchDirection.Vertical

      Dim postNetPlanetReadOptions As PostNetPlanetBarcodeReadOptions = DirectCast(reader.GetDefaultOptions(BarcodeSymbology.PostNet).Clone(), PostNetPlanetBarcodeReadOptions)
      postNetPlanetReadOptions.SearchDirection = BarcodeSearchDirection.Vertical

      Dim gs1StackedReadOptions As GS1DatabarStackedBarcodeReadOptions = DirectCast(reader.GetDefaultOptions(BarcodeSymbology.GS1DatabarStacked).Clone(), GS1DatabarStackedBarcodeReadOptions)
      gs1StackedReadOptions.SearchDirection = BarcodeSearchDirection.Vertical

      Dim patchCodeReadOptions As PatchCodeBarcodeReadOptions = DirectCast(reader.GetDefaultOptions(BarcodeSymbology.PatchCode).Clone(), PatchCodeBarcodeReadOptions)
      patchCodeReadOptions.SearchDirection = BarcodeSearchDirection.Vertical

      Dim pdf417ReadOptions As PDF417BarcodeReadOptions = DirectCast(reader.GetDefaultOptions(BarcodeSymbology.PDF417).Clone(), PDF417BarcodeReadOptions)
      pdf417ReadOptions.SearchDirection = BarcodeSearchDirection.Vertical

      Dim microPdf417ReadOptions As MicroPDF417BarcodeReadOptions = DirectCast(reader.GetDefaultOptions(BarcodeSymbology.MicroPDF417).Clone(), MicroPDF417BarcodeReadOptions)
      microPdf417ReadOptions.SearchDirection = BarcodeSearchDirection.Vertical

      ' Even though this array will not contain all options, it should be enough to read all barcodes, since the version of ReadBarcodes we will use
      ' will use the default options if an overriden is not passed
      Dim readOptions() As BarcodeReadOptions = _
      { _
         oneDReadOptions, fourStateReadOptions, postNetPlanetReadOptions, gs1StackedReadOptions, patchCodeReadOptions, pdf417ReadOptions, microPdf417ReadOptions _
      }

      Return readOptions
   End Function

Public NotInheritable Class LEAD_VARS
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images"
End Class