Private VSTwain1 As New VintaSoftTwain()


''' <summary>
''' Scans images asynchronously.
''' </summary>
Private Sub ScanImages()
    ' open the device manager
    If Not VSTwain1.DeviceManager_Open() Then
        Console.WriteLine(VSTwain1.errorString)
        Exit Sub
    End If

    ' select device using standard device selection dialog
    VSTwain1.DeviceManager_ShowDefaultDeviceSelectionDialog()

    ' open the device
    If Not VSTwain1.Device_Open Then
        Console.WriteLine(VSTwain1.errorString)
        Exit Sub
    End If

    ' specify that device UI must be shown
    VSTwain1.Device_ShowUI = True

    ' subscribe to the device events
    AddHandler VSTwain1.DeviceImageAcquired, AddressOf VSTwain1_ImageAcquired
    AddHandler VSTwain1.DeviceScanCompleted, AddressOf VSTwain1_ScanCompleted
    AddHandler VSTwain1.DeviceScanFailed, AddressOf VSTwain1_ScanFailed
    AddHandler VSTwain1.DeviceScanCanceled, AddressOf VSTwain1_ScanCanceled

    ' acquire images asynchronously
    VSTwain1.Device_AcquireImage()
End Sub

Private Sub VSTwain1_ImageAcquired()
    ' get index of acquired image
    Dim imageIndex As Integer = VSTwain1.AcquiredImages_Count - 1

    'Dim arrPixels() As Byte       ' VB 6.0 syntax
    Dim arrPixels(,,) As Byte      ' VB.NET syntax
    Dim x As Long, y As Long, width As Long, height As Long
    ' get the first image from the buffer
    arrPixels = VSTwain1.AcquiredImages_GetImageAsByteArray(imageIndex)
    If VSTwain1.Error Then
        Console.WriteLine(VSTwain1.errorString)
    Else
        width = UBound(arrPixels, 2) - LBound(arrPixels, 2)
        height = UBound(arrPixels, 3) - LBound(arrPixels, 3)

        Dim Image1 As Drawing.Bitmap = New Drawing.Bitmap(CInt(width + 1), CInt(height + 1), Drawing.Imaging.PixelFormat.Format24bppRgb)

        For x = width To 0 Step -1
            For y = height To 0 Step -1
                Image1.SetPixel(x, height - y, Drawing.Color.FromArgb(arrPixels(2, x, y), arrPixels(1, x, y), arrPixels(0, x, y)))
            Next y
        Next x
    End If
End Sub

Private Sub VSTwain1_ScanCompleted()
    Console.WriteLine("Scan is completed.")
End Sub

Private Sub VSTwain1_ScanFailed(errorString As String)
    Console.WriteLine(String.Format("Scan is failed: {0}.", errorString))
End Sub

Private Sub VSTwain1_ScanCanceled()
    Console.WriteLine("Scan is canceled.")
End Sub