VintaSoft Barcode .NET SDK v10.0
Barcode symbologies supported by barcode reader

The SDK allows to read barcodes, which are based on the following barcode symbologies:


The ReaderSettings.ScanBarcodeTypes property (barcodeReader.Settings.ScanBarcodeTypes) specifies the barcode symbologies the reader must search for on the image.


Some barcode symbologies may have subsets, for example, GS1-128 barcode symbology is a subset of Code128 barcode symbology. The BarcodeSymbologySubset class is an abstract base class that allows to define the barcode symbology subset. The SDK has definitions for the following barcode symbology subsets:

The ReaderSettings.ScanBarcodeSubsets (barcodeReader.Settings.ScanBarcodeSubsets) property specifies the list of barcode symbology subsets the barcode reader must search for on the image.

The usage of barcode symbology subsets allows to classify the found barcode as one of barcode symbology subset during the barcode recognition. This could lead to significant increase of barcode recognition speed and allows to use ReaderSettings.ExpectedBarcodes property for specifying the expected barcode count.


The architecture, which allows to work with subsets of barcode symbologies, is open and allows to define custom subsets of barcode symbologies. While defining the barcode symbology subset is necessary to override the BarcodeSymbologySubset.Decode method, which defines the algorithm for converting the source barcode symbology value into the barcode symbology subset value. The BarcodeSymbologySubset.Encode method also can be overriden but this is not obligatory, this method defines the algorithm of converting a barcode symbology subset value into the source barcode symbology value.

Here is an example, which demonstrates how to define a subset for Code39 barcodes with checksum modulo 256:
Imports System.Drawing

Imports Vintasoft.Barcode.SymbologySubsets
Imports Vintasoft.Barcode
Imports Vintasoft.Barcode.BarcodeInfo

''' <summary>
''' Test that demonstrates how to generate an image with Code39 barcode with checksum modulo 256
''' and how to read Code39 barcode with checksum modulo 256 in image.
''' </summary>
Public NotInheritable Class Code39Checksum256SymbologyTest
        Private Sub New()
        End Sub

        ''' <summary>
        ''' Runs the test.
        ''' </summary>
        Public Shared Sub Test()
                Test("TEST12345")
                Test("ABCDEF")
                Test("AB")
                Test("123456789")
        End Sub

        ''' <summary>
        ''' Runs the test for a single barcode value.
        ''' </summary>
        Public Shared Sub Test(value As String)
                ' create an object that defines Code39 barcodes with checksum modulo 256
                Dim code39Checksum256 As New Code39Checksum256Symbology()

                ' create the barcode writer
                Dim writer As New BarcodeWriter()

                ' specify that writer must generate Code39 barcode AND
                ' set the barcode value with checksum
                code39Checksum256.Encode(value, writer.Settings)

                ' create image with Code39 barcode with checksum
                Using imageWithCode39BarcodeWithChecksum As Image = writer.GetBarcodeAsBitmap()
                        ' specify that writer must generate Code39 barcode
                        writer.Settings.Barcode = BarcodeType.Code39

                        ' set the barcode value without checksum
                        writer.Settings.Value = value

                        ' create image with barcode without checksum
                        Using imageWithCode39Barcode As Image = writer.GetBarcodeAsBitmap()
                                ' create the barcode reader
                                Using reader As New BarcodeReader()
                                        ' specify that reader must search for Code39 with checksum only

                                        reader.Settings.ScanBarcodeTypes = BarcodeType.None
                                        reader.Settings.ScanBarcodeSubsets.Add(code39Checksum256)

                                        ' read barcode from image with barcode with checksum
                                        Dim infos As IBarcodeInfo() = reader.ReadBarcodes(imageWithCode39BarcodeWithChecksum)

                                        ' show information about found barcode

                                        Dim subsetInfo As BarcodeSubsetInfo = DirectCast(infos(0), BarcodeSubsetInfo)
                                        Console.WriteLine("Detected '{0}' barcode, value = {1}, base value = {2}.", subsetInfo.BarcodeSubset.Name, subsetInfo.Value, subsetInfo.BaseBarcodeInfo.Value)


                                        ' read barcodes from image with barcode without checksum
                                        infos = reader.ReadBarcodes(imageWithCode39Barcode)
                                        ' if barcode is found
                                        If infos.Length <> 0 Then
                                                ' throw exception
                                                Throw New ApplicationException()
                                        End If
                                End Using
                        End Using
                End Using
        End Sub
End Class

''' <summary>
''' Represents the barcode symbology subset that includes Code39 barcodes with checksum modulo 256.
''' </summary>
Public Class Code39Checksum256Symbology
        Inherits BarcodeSymbologySubset

        #Region "Properties"

        ''' <summary>
        ''' Gets a name of barcode symbology subset.
        ''' </summary>
        Public Overrides ReadOnly Property Name() As String
                Get
                        Return "Code39 CH256"
                End Get
        End Property

        ''' <summary>
        ''' Gets a base barcode symbology type of this barcode symbology subset.
        ''' </summary>
        Public Overrides ReadOnly Property BaseType() As BarcodeType
                Get
                        Return BarcodeType.Code39
                End Get
        End Property

        #End Region



        #Region "Methods"

        ''' <summary>
        ''' Decodes the Code39 barcode value into Code39 barcode value with checksum modulo 256.
        ''' </summary>
        ''' <param name="info">Code39 barcode value.</param>
        ''' <returns>Code39 barcode value with checksum modulo 256.</returns>
        Public Overrides Function Decode(info As IBarcodeInfo) As BarcodeSubsetInfo
                If info.Value IsNot Nothing AndAlso info.Value.Length >= 4 Then
                        ' get the barcode checksum
                        Dim checksum As String = info.Value.Substring(info.Value.Length - 2)
                        ' get the barcode value
                        Dim value As String = info.Value.Substring(0, info.Value.Length - 2)
                        ' if barcode checksum is correct
                        If checksum = GenerateChecksum256(value) Then
                                Dim result As New BarcodeSubsetInfo(info, Me, New TextValueItem(value))
                                result.Confidence = 100
                                Return result
                        End If
                End If
                Return Nothing
        End Function

        ''' <summary>
        ''' Encodes the Code39 barcode value with checksum modulo 256 into the Code39 barcode value
        ''' using provided barcode writer settings and
        ''' saves the source barcode symbology value in the barcode writer settings.
        ''' </summary>
        ''' <param name="value">Code39 barcode value with checksum modulo 256 to encode.</param>
        ''' <param name="settings">Barcode writer settings.</param>
        Public Overrides Sub Encode(value As ValueItemBase, settings As WriterSettings)
                Dim textValue As String = value.ToString()
                If textValue.Length < 2 Then
                        Throw New WriterSettingsException(WriterSettingsExceptionType.ExpectedNSymbolsInBarcodeValue, "minimum two symbols")
                End If

                ' specify the barcode symbology type
                settings.Barcode = Me.BaseType
                ' add checksum to the barcode value
                settings.Value = String.Format("{0}{1}", textValue, GenerateChecksum256(textValue))
        End Sub

        ''' <summary>
        ''' Calculates simple checksum modulo 256.
        ''' </summary>
        ''' <param name="value">Text value.</param>
        ''' <returns>Checksum in HEX format.</returns>
        Private Shared Function GenerateChecksum256(value As String) As String
                Dim checksum As Integer = 0
                For i As Integer = 0 To value.Length - 1
                        Dim symbol As Integer = AscW(value(i)) Mod 39
                        If i Mod 2 = 0 Then
                                checksum += symbol
                        Else
                                checksum += symbol * 3
                        End If
                Next
                checksum = checksum Mod 256
                Return checksum.ToString("X2")
        End Function

        #End Region

End Class

' This code example produces the following output:
'
'   Detected 'Code39 CH256' barcode, value = TEST12345, base value = TEST12345E3.
'   Detected 'Code39 CH256' barcode, value = ABCDEF, base value = ABCDEF59.
'   Detected 'Code39 CH256' barcode, value = AB, base value = AB6B.
'   Detected 'Code39 CH256' barcode, value = 123456789, base value = 123456789EE.
'

              
using System;
using System.Drawing;

using Vintasoft.Barcode.SymbologySubsets;
using Vintasoft.Barcode;
using Vintasoft.Barcode.BarcodeInfo;

/// <summary>
/// Test that demonstrates how to generate an image with Code39 barcode with checksum modulo 256
/// and how to read Code39 barcode with checksum modulo 256 in image.
/// </summary>
public static class Code39Checksum256SymbologyTest
{

    /// <summary>
    /// Runs the test.
    /// </summary>
    public static void Test()
    {
        Test("TEST12345");
        Test("ABCDEF");
        Test("AB");
        Test("123456789");
    }

    /// <summary>
    /// Runs the test for a single barcode value.
    /// </summary>
    public static void Test(string value)
    {
        // create an object that defines Code39 barcodes with checksum modulo 256
        Code39Checksum256Symbology code39Checksum256 = new Code39Checksum256Symbology();

        // create the barcode writer
        BarcodeWriter writer = new BarcodeWriter();

        // specify that writer must generate Code39 barcode AND
        // set the barcode value with checksum
        code39Checksum256.Encode(value, writer.Settings);

        // create image with Code39 barcode with checksum
        using (Image imageWithCode39BarcodeWithChecksum = writer.GetBarcodeAsBitmap())
        {
            // specify that writer must generate Code39 barcode
            writer.Settings.Barcode = BarcodeType.Code39;

            // set the barcode value without checksum
            writer.Settings.Value = value;

            // create image with barcode without checksum
            using (Image imageWithCode39Barcode = writer.GetBarcodeAsBitmap())
            {
                // create the barcode reader
                using (BarcodeReader reader = new BarcodeReader())
                {
                    // specify that reader must search for Code39 with checksum only

                    reader.Settings.ScanBarcodeTypes = BarcodeType.None;
                    reader.Settings.ScanBarcodeSubsets.Add(code39Checksum256);

                    // read barcode from image with barcode with checksum
                    IBarcodeInfo[] infos = reader.ReadBarcodes(imageWithCode39BarcodeWithChecksum);

                    // show information about found barcode

                    BarcodeSubsetInfo subsetInfo = ((BarcodeSubsetInfo)infos[0]);
                    Console.WriteLine("Detected '{0}' barcode, value = {1}, base value = {2}.",
                        subsetInfo.BarcodeSubset.Name,
                        subsetInfo.Value,
                        subsetInfo.BaseBarcodeInfo.Value);


                    // read barcodes from image with barcode without checksum
                    infos = reader.ReadBarcodes(imageWithCode39Barcode);
                    // if barcode is found
                    if (infos.Length != 0)
                        // throw exception
                        throw new ApplicationException();
                }
            }
        }
    }
}

/// <summary>
/// Represents the barcode symbology subset that includes Code39 barcodes with checksum modulo 256.
/// </summary>
public class Code39Checksum256Symbology : BarcodeSymbologySubset
{

    #region Properties

    /// <summary>
    /// Gets a name of barcode symbology subset.
    /// </summary>
    public override string Name
    {
        get
        {
            return "Code39 CH256";
        }
    }

    /// <summary>
    /// Gets a base barcode symbology type of this barcode symbology subset.
    /// </summary>
    public override BarcodeType BaseType
    {
        get
        {
            return BarcodeType.Code39;
        }
    }

    #endregion



    #region Methods

    /// <summary>
    /// Decodes the Code39 barcode value into Code39 barcode value with checksum modulo 256.
    /// </summary>
    /// <param name="info">Code39 barcode value.</param>
    /// <returns>Code39 barcode value with checksum modulo 256.</returns>
    public override BarcodeSubsetInfo Decode(IBarcodeInfo info)
    {
        if (info.Value != null && info.Value.Length >= 4)
        {
            // get the barcode checksum
            string checksum = info.Value.Substring(info.Value.Length - 2);
            // get the barcode value
            string value = info.Value.Substring(0, info.Value.Length - 2);
            // if barcode checksum is correct
            if (checksum == GenerateChecksum256(value))
            {
                BarcodeSubsetInfo result = new BarcodeSubsetInfo(info, this, new TextValueItem(value));
                result.Confidence = 100;
                return result;
            }
        }
        return null;
    }

    /// <summary>
    /// Encodes the Code39 barcode value with checksum modulo 256 into the Code39 barcode value
    /// using provided barcode writer settings and
    /// saves the source barcode symbology value in the barcode writer settings.
    /// </summary>
    /// <param name="value">Code39 barcode value with checksum modulo 256 to encode.</param>
    /// <param name="settings">Barcode writer settings.</param>
    public override void Encode(ValueItemBase value, WriterSettings settings)
    {
        string textValue = value.ToString();
        if (textValue.Length < 2)
            throw new WriterSettingsException(
                WriterSettingsExceptionType.ExpectedNSymbolsInBarcodeValue, 
                "minimum two symbols");

        // specify the barcode symbology type
        settings.Barcode = this.BaseType;
        // add checksum to the barcode value
        settings.Value = string.Format("{0}{1}", textValue, GenerateChecksum256(textValue));
    }

    /// <summary>
    /// Calculates simple checksum modulo 256.
    /// </summary>
    /// <param name="value">Text value.</param>
    /// <returns>Checksum in HEX format.</returns>
    private static string GenerateChecksum256(string value)
    {
        int checksum = 0;
        for (int i = 0; i < value.Length; i++)
        {
            int symbol = (int)value[i] % 39;
            if (i % 2 == 0)
                checksum += symbol;
            else
                checksum += symbol * 3;
        }
        checksum = checksum % 256;
        return checksum.ToString("X2");
    }

    #endregion

}

/* This code example produces the following output:
     
   Detected 'Code39 CH256' barcode, value = TEST12345, base value = TEST12345E3.
   Detected 'Code39 CH256' barcode, value = ABCDEF, base value = ABCDEF59.
   Detected 'Code39 CH256' barcode, value = AB, base value = AB6B.
   Detected 'Code39 CH256' barcode, value = 123456789, base value = 123456789EE.
*/