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Read Barcode From Live Video Cam (simplified) - VB.NET

BarCode Reader SDK sample in VB.NET demonstrating ‘Read Barcode From Live Video Cam (simplified)’

Program.vb
Imports System.Windows.Forms

NotInheritable Class Program
	Private Sub New()
	End Sub
	''' <summary>
	''' The main entry point for the application.
	''' </summary>
	<MTAThread> _
	Friend Shared Sub Main()
		Application.EnableVisualStyles()
		Application.SetCompatibleTextRenderingDefault(False)

        ' Show barcode decoder dialog and get decoded barcode value
        Dim decodedBarcodeValue As String = WebCamBarcodeDecoder.DecodeBarcode()

        If decodedBarcodeValue IsNot Nothing Then
            MessageBox.Show("Found barcode: " & decodedBarcodeValue)
        Else
            MessageBox.Show("Decoding cancelled")
        End If

    End Sub
End Class

WebCamBarcodeDecoder.Designer.vb
��Partial Class WebCamBarcodeDecoder

	''' <summary>

	''' Required designer variable.

	''' </summary>

	Private components As System.ComponentModel.IContainer = Nothing



	''' <summary>

	''' Clean up any resources being used.

	''' </summary>

	''' <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>

	Protected Overrides Sub Dispose(disposing As Boolean)

		If disposing AndAlso (components IsNot Nothing) Then

			components.Dispose()

		End If

		MyBase.Dispose(disposing)

	End Sub



	#Region "Windows Form Designer generated code"



	''' <summary>

	''' Required method for Designer support - do not modify

	''' the contents of this method with the code editor.

	''' </summary>

	Private Sub InitializeComponent()

        Me.pictureVideoPreview = New System.Windows.Forms.PictureBox()

        Me.btnCancel = New System.Windows.Forms.Button()

        CType(Me.pictureVideoPreview, System.ComponentModel.ISupportInitialize).BeginInit()

        Me.SuspendLayout()

        '

        'pictureVideoPreview

        '

        Me.pictureVideoPreview.Anchor = CType((((System.Windows.Forms.AnchorStyles.Top Or System.Windows.Forms.AnchorStyles.Bottom) _

            Or System.Windows.Forms.AnchorStyles.Left) _

            Or System.Windows.Forms.AnchorStyles.Right), System.Windows.Forms.AnchorStyles)

        Me.pictureVideoPreview.BackColor = System.Drawing.Color.White

        Me.pictureVideoPreview.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D

        Me.pictureVideoPreview.Location = New System.Drawing.Point(12, 12)

        Me.pictureVideoPreview.Name = "pictureVideoPreview"

        Me.pictureVideoPreview.Size = New System.Drawing.Size(640, 480)

        Me.pictureVideoPreview.SizeMode = System.Windows.Forms.PictureBoxSizeMode.CenterImage

        Me.pictureVideoPreview.TabIndex = 8

        Me.pictureVideoPreview.TabStop = False

        '

        'btnCancel

        '

        Me.btnCancel.Anchor = CType((System.Windows.Forms.AnchorStyles.Bottom Or System.Windows.Forms.AnchorStyles.Right), System.Windows.Forms.AnchorStyles)

        Me.btnCancel.DialogResult = System.Windows.Forms.DialogResult.Cancel

        Me.btnCancel.Font = New System.Drawing.Font("Tahoma", 8.25!, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, CType(204, Byte))

        Me.btnCancel.Location = New System.Drawing.Point(562, 497)

        Me.btnCancel.Name = "btnCancel"

        Me.btnCancel.Size = New System.Drawing.Size(90, 26)

        Me.btnCancel.TabIndex = 4

        Me.btnCancel.Text = "Cancel"

        Me.btnCancel.UseVisualStyleBackColor = True

        '

        'WebCamBarcodeDecoder

        '

        Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)

        Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font

        Me.CancelButton = Me.btnCancel

        Me.ClientSize = New System.Drawing.Size(664, 536)

        Me.Controls.Add(Me.btnCancel)

        Me.Controls.Add(Me.pictureVideoPreview)

        Me.MaximizeBox = False

        Me.Name = "WebCamBarcodeDecoder"

        Me.ShowIcon = False

        Me.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen

        Me.Text = "QR Code decoder"

        CType(Me.pictureVideoPreview, System.ComponentModel.ISupportInitialize).EndInit()

        Me.ResumeLayout(False)



    End Sub



#End Region



    Private pictureVideoPreview As System.Windows.Forms.PictureBox

    Private WithEvents btnCancel As System.Windows.Forms.Button

End Class




WebCamBarcodeDecoder.vb
Imports System
Imports System.ComponentModel
Imports System.Drawing
Imports System.Windows.Forms
Imports System.Threading
Imports Bytescout.BarCodeReader
Imports TouchlessLib


Partial Public Class WebCamBarcodeDecoder
    Inherits Form

    ' Touchless API library manager (to use it you should have TouchlessLib.dll referenced and WebCamLib.dll copied to the output directory).
    Private _touchlessLibManager As TouchlessMgr

    ' Background barcode decoding thread.
    Private ReadOnly _backgroundWorker As New BackgroundWorker()

    ' Array with all latest barcodes from the last scanning session.
    Public FoundBarcode As String = Nothing

    ' Form initialization.
    Public Sub New()

        InitializeComponent()

        ' Setup background working thread 
        _backgroundWorker.WorkerSupportsCancellation = True
        AddHandler _backgroundWorker.DoWork, New DoWorkEventHandler(AddressOf BackgroundWorker_DoWork)
        AddHandler _backgroundWorker.RunWorkerCompleted, New RunWorkerCompletedEventHandler(AddressOf BackgroundWorker_RunWorkerCompleted)

    End Sub

    ' On form loading.
    Private Sub VideoScanForm_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        ' Initialize camera and cancel if no camera avalaible
        If InitCamera() = False Then
            DialogResult = New DialogResult()
            Close()
        End If

        StartDecoding()

    End Sub

    ' Camera initialization.
    Private Function InitCamera() As Boolean

        ' Create Touchless API library manager to work with web camera
        _touchlessLibManager = New TouchlessMgr()

        If _touchlessLibManager.Cameras.Count = 0 Then
            MessageBox.Show("No camera devices available.")
            Return False
        End If

        ' Get first available web camera 
        Dim camera As Camera = _touchlessLibManager.Cameras(0)
        ' ... and set it as the current device
        _touchlessLibManager.CurrentCamera = camera

        ' Set camera image dimensions acquired from camera
        camera.CaptureWidth = 640
        camera.CaptureHeight = 480

        ' Handle camera's OnImageCaptured event
        AddHandler camera.OnImageCaptured, New EventHandler(Of CameraEventArgs)(AddressOf CurrentCamera_OnImageCaptured)

        Return True

    End Function

    Public Sub StartDecoding()

        ' Start the background decoding thread
        _backgroundWorker.RunWorkerAsync()

    End Sub

    Private Sub StopDecoding()

        ' Signal the background thread to stop
        _backgroundWorker.CancelAsync()

    End Sub

    Private Sub DeinitCamera()

        If _touchlessLibManager IsNot Nothing Then
            If _touchlessLibManager.CurrentCamera IsNot Nothing Then
                RemoveHandler _touchlessLibManager.CurrentCamera.OnImageCaptured, AddressOf CurrentCamera_OnImageCaptured
                _touchlessLibManager.CurrentCamera = Nothing
            End If
        End If
        _touchlessLibManager.Dispose()
        _touchlessLibManager = Nothing

    End Sub

    ' Barcode decoding procedure executing in the background thread.
    Private Sub BackgroundWorker_DoWork(ByVal sender As Object, ByVal e As DoWorkEventArgs)

        Dim worker As BackgroundWorker = TryCast(sender, BackgroundWorker)

        ' Create barcode reader instance
        Dim reader As New Reader()
        reader.RegistrationName = "demo"
        reader.RegistrationKey = "demo"

        ' Enable QR Code decoding
        reader.BarcodeTypesToFind.QRCode = True

        Try

            ' Get image from camera every 1.5s and try to find a barcode on it
            While True

                ' If the decoding is canceled then exit
                If (worker.CancellationPending = True) Then
                    e.Cancel = True
                    Return
                Else
                    ' get current frame bitmap from camera using Touchless lib
                    Dim bitmap As Bitmap = _touchlessLibManager.CurrentCamera.GetCurrentImage()
                    If bitmap IsNot Nothing Then

                        ' -----------------------------------------------------------------------
                        ' NOTE: We can read barcodes from specific page to increase performance .
                        ' For sample please refer to "Decoding barcodes from PDF by pages" program.
                        ' ----------------------------------------------------------------------- 

                        ' Search barcodes
                        Dim result As FoundBarcode() = reader.ReadFrom(bitmap)
                        If result IsNot Nothing And result.Length > 0 Then
                            ' return value of the first found barcode
                            e.Result = result(0).Value
                            Return
                        End If
                    End If

                    ' Pause the loop for 1.5s
                    Thread.Sleep(1500)
                End If

            End While

        Finally
            reader.Dispose()
        End Try

    End Sub

    ' Background thread procedure is finished
    Private Sub BackgroundWorker_RunWorkerCompleted(ByVal sender As Object, ByVal e As RunWorkerCompletedEventArgs)

        ' If decoding is not canceled then get the decoding result from background thread and close the form
        If Not e.Cancelled Then

            ' Get barcode value for background thread result
            FoundBarcode = DirectCast(e.Result, String)

            ' Close form with OK result
            DialogResult = DialogResult.OK
            Close()

        End If

    End Sub

    ' Update picture box with the last captured frame from web camera.
    Private Sub CurrentCamera_OnImageCaptured(ByVal sender As Object, ByVal e As CameraEventArgs)

        pictureVideoPreview.Image = _touchlessLibManager.CurrentCamera.GetCurrentImage()

    End Sub

    ' Cancel button click.
    Private Sub btnCancel_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnCancel.Click

        DialogResult = DialogResult.Cancel
        Close()

    End Sub

    ' On form closing.
    Private Sub VideoScanForm_FormClosing(ByVal sender As System.Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles MyBase.FormClosing

        StopDecoding()

        DeinitCamera()

    End Sub

    ' Shared (static) function for convenient use. 
    ' It creates the form and returns the decoded barcode value as string.
    ' Returns Nothing if the decoding is canceled.
    Public Shared Function DecodeBarcode() As String

        Dim form As New WebCamBarcodeDecoder()

        If form.ShowDialog() = DialogResult.OK Then

            Return form.FoundBarcode

        End If

        Return Nothing

    End Function

End Class

Download Source Code (.zip)

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