EAN13 Barcode Control

• Download source code - 53 KB

Introduction

In 2005, most of my work was barcode related programs, because I was writing programs for hand held devices which came with an integrated barcode reader. It was exciting to know about the barcode technology and how third party tools drew these bars. So I started looking for some resources to understand the algorithm used to generate barcodes. I discovered a lot of barcode types and each type had its own algorithm. My goal was to create my own barcode controls.

In the beginning of 2006, I started with this EAN13 barcode. After that, I paused because I found other exciting technologies. I know there are many articles in CodeProject that talk about the EAN 13 barcode, but I would like to share this with you.

Using the Code

This function initializes the barcode table which we will use to draw the bars:

Public Sub InitEAN13Tables()
    '          Zero
    Tables(0).TableA = "0001101"
    Tables(0).TableB = "0100111"
    Tables(0).TableC = "1110010"
    '          One
    Tables(1).TableA = "0011001"
    Tables(1).TableB = "0110011"
    Tables(1).TableC = "1100110"
    '          Two
    Tables(2).TableA = "0010011"
    Tables(2).TableB = "0011011"
    Tables(2).TableC = "1101100"
    '          Three
    Tables(3).TableA = "0111101"
    Tables(3).TableB = "0100001"
    Tables(3).TableC = "1000010"
    '          Four
    Tables(4).TableA = "0100011"
    Tables(4).TableB = "0011101"
    Tables(4).TableC = "1011100"
    '          Five
    Tables(5).TableA = "0110001"
    Tables(5).TableB = "0111001"
    Tables(5).TableC = "1001110"
    '          Six
    Tables(6).TableA = "0101111"
    Tables(6).TableB = "0000101"
    Tables(6).TableC = "1010000"
    '          Seven
    Tables(7).TableA = "0111011"
    Tables(7).TableB = "0010001"
    Tables(7).TableC = "1000100"
    '          Eight
    Tables(8).TableA = "0110111"
    Tables(8).TableB = "0001001"
    Tables(8).TableC = "1001000"
    '          Nine
    Tables(9).TableA = "0001011"
    Tables(9).TableB = "0010111"
    Tables(9).TableC = "1110100"
End Sub

The function CalculateCheckSum calculates the checksum code for the barcode:

Private Function CalculateCheckSum() As Boolean
    Dim X As Integer = 0
    Dim Y As Integer = 0
    Dim j As Integer = 11
    Try
        For i As Integer = 1 To 12
            If i Mod 2 = 0 Then
                X += Val(m_BarcodeText(j))
            Else
                Y += Val(m_BarcodeText(j))
            End If
            j -= 1
        Next

        Dim Z As Integer = X + (3 * Y)
        'first way
        m_CheckSum = ((10 - (Z Mod 10)) Mod 10)
        'second way
        'Dim M As Integer = Z
        ' Do Until (M Mod 10 = 0)
        'M += 1
        ' Loop
        'm_CheckSum = M - Z

        Return True
    Catch ex As Exception
        MessageBox.Show(ex.Message)
        Return False
    End Try
End Function

CalculateValue is the main function which calculates the barcode values depending on the barcode table:

Private Function CalculateValue() As Boolean
    ' Clear any previous Value
    BarcodeValue = New StringBuilder(95)
    Try
        ' Add The Start Mark
        BarcodeValue.Append(StartMark)
        Select Case m_BarcodeText(0)
            Case "0"
                For i As Integer = 1 To 6
                    BarcodeValue.Append(Tables(Val(m_BarcodeText(i))).TableA)
                Next
            Case "1"
                For i As Integer = 1 To 6
                    If (i = 1) Or (i = 2) Or (i = 4) Then
                        BarcodeValue.Append(Tables(Val(m_BarcodeText(i))).TableA)
                    Else
                        BarcodeValue.Append(Tables(Val(m_BarcodeText(i))).TableB)
                    End If
                Next
            Case "2"
                For i As Integer = 1 To 6
                    If (i = 1) Or (i = 2) Or (i = 5) Then
                        BarcodeValue.Append(Tables(Val(m_BarcodeText(i))).TableA)
                    Else
                        BarcodeValue.Append(Tables(Val(m_BarcodeText(i))).TableB)
                    End If
                Next
            Case "3"
                For i As Integer = 1 To 6
                    If (i = 1) Or (i = 2) Or (i = 6) Then
                        BarcodeValue.Append(Tables(Val(m_BarcodeText(i))).TableA)
                    Else
                        BarcodeValue.Append(Tables(Val(m_BarcodeText(i))).TableB)
                    End If
                Next
            Case "4"
                For i As Integer = 1 To 6
                    If (i = 1) Or (i = 3) Or (i = 4) Then
                        BarcodeValue.Append(Tables(Val(m_BarcodeText(i))).TableA)
                    Else
                        BarcodeValue.Append(Tables(Val(m_BarcodeText(i))).TableB)
                    End If
                Next
            Case "5"
                For i As Integer = 1 To 6
                    If (i = 1) Or (i = 4) Or (i = 5) Then
                        BarcodeValue.Append(Tables(Val(m_BarcodeText(i))).TableA)
                    Else
                        BarcodeValue.Append(Tables(Val(m_BarcodeText(i))).TableB)
                    End If
                Next
            Case "6"
                For i As Integer = 1 To 6
                    If (i = 1) Or (i = 5) Or (i = 6) Then
                        BarcodeValue.Append(Tables(Val(m_BarcodeText(i))).TableA)
                    Else
                        BarcodeValue.Append(Tables(Val(m_BarcodeText(i))).TableB)
                    End If
                Next
            Case "7"
                For i As Integer = 1 To 6
                    If (i = 1) Or (i = 3) Or (i = 5) Then
                        BarcodeValue.Append(Tables(Val(m_BarcodeText(i))).TableA)
                    Else
                        BarcodeValue.Append(Tables(Val(m_BarcodeText(i))).TableB)
                    End If
                Next
            Case "8"
                For i As Integer = 1 To 6
                    If (i = 1) Or (i = 3) Or (i = 6) Then
                        BarcodeValue.Append(Tables(Val(m_BarcodeText(i))).TableA)
                    Else
                        BarcodeValue.Append(Tables(Val(m_BarcodeText(i))).TableB)
                    End If
                Next
            Case "9"
                For i As Integer = 1 To 6
                    If (i = 1) Or (i = 4) Or (i = 6) Then
                        BarcodeValue.Append(Tables(Val(m_BarcodeText(i))).TableA)
                    Else
                        BarcodeValue.Append(Tables(Val(m_BarcodeText(i))).TableB)
                    End If
                Next
        End Select
        ' Add The Splitting Mark
        BarcodeValue.Append(SplittingMark)

        For i As Integer = 7 To (m_BarcodeText.Length - 1)
            BarcodeValue.Append(Tables(Val(m_BarcodeText(i))).TableC)
        Next
        ' Add Checksum
        BarcodeValue.Append(Tables(CheckSum).TableC)
        ' Add The End Mark
        BarcodeValue.Append(EndMark)

    Catch ex As Exception
        MessageBox.Show(ex.Message)
    End Try
End Function

Points of Interest

This barcode control was created just for fun and is not a professional control. We can add many properties to this. I think the bar sizes need some extra handling to enable printing in deferent sizes. Maybe if I have some time, I will write controls for other barcode types like pdf417.

Enjoy :)