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

' 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 name containing the barcodes
   Public ImageFileName As String

   ' Image containing the barcodes
   Public Image As RasterImage

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

   ' In case of errors
   Public [Error] As Exception

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

<TestMethod(), Asynchronous()> _
Public Sub BarcodeReaderReadBarcodeExample6()
   BarcodeReader_ReadBarcodeExample6()
   EnqueueTestComplete()
End Sub

Public Sub BarcodeReader_ReadBarcodeExample6()
   Dim images As RasterImage() = New RasterImage(1) {}
   Dim originalImageFileName As String = "Barcode1.tif"
   Dim rotatedImageFileName As String = "Barcode1_Rotated90.tif"
   Dim imageFileNames As String() = New String() {originalImageFileName, rotatedImageFileName}

   Using outputStream As SampleImageStream = New SampleImageStream("Barcode1_Rotated90.tif")
      images(0) = SampleImage.Get(SampleImageNames.Barcode1_tif).Clone()
      images(1) = SampleImage.Get(SampleImageNames.Barcode1_tif).Clone()
      RotateImage(images(1))

      ' Create a Barcode engine
      Dim engine As BarcodeEngine = 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 As AutoResetEvent() = New AutoResetEvent(1) {}

      ' Create the thread data objects
      Dim threadsData As MyThreadData() = New MyThreadData(1) {}
      Dim i As Integer = 0
      Do While i < threadsData.Length
         finishedEvents(i) = New AutoResetEvent(False)

         threadsData(i) = New MyThreadData()
         threadsData(i).BarcodeReaderInstance = reader
         threadsData(i).ReadOptions = Nothing
         threadsData(i).FinishedEvent = finishedEvents(i)
         i += 1
      Loop

      ' 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 List(Of BarcodeData) = New List(Of BarcodeData)()

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

         For i = 0 To 1
            ' Clear the previous results (if any), set up the file name and run
            threadsData(i).Barcodes = Nothing
            threadsData(i).Error = Nothing
            threadsData(i).Image = image
            threadsData(i).ImageFileName = imageFileNames(index)
            ThreadPool.QueueUserWorkItem(New WaitCallback(AddressOf ReadBarcodesInThread), threadsData(i))
         Next i

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

         ' Add the barcodes found to our list
         For i = 0 To 1
            If Not threadsData(i).Error Is Nothing Then
               Console.WriteLine("{0} had error {1}", threadsData(i).Name, threadsData(i).Error)
            ElseIf Not threadsData(i).Barcodes Is Nothing Then
               totalBarcodes.AddRange(threadsData(i).Barcodes)
            End If
         Next i

         index += 1
      Next image

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

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

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

   Try
      ' Load the image
      Dim codecs As RasterCodecs = 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

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

Private Shared Sub RotateImage(ByVal image As RasterImage)
   ' Create a 90 degrees rotated version of Barcode1.tif

   Dim codecs As RasterCodecs = New RasterCodecs()

   Dim rotate As RotateCommand = New RotateCommand(90 * 100, RotateCommandFlags.Resize, RasterColor.FromKnownColor(RasterKnownColor.White))
   rotate.Run(image)
End Sub

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 = TryCast(reader.GetDefaultOptions(BarcodeSymbology.UPCA).Clone(), OneDBarcodeReadOptions)
   oneDReadOptions.SearchDirection = BarcodeSearchDirection.Vertical

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

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

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

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

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

   Dim microPdf417ReadOptions As MicroPDF417BarcodeReadOptions = TryCast(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