Imports Vintasoft.Barcode.SymbologySubsets   
Imports Vintasoft.Barcode   
Imports Vintasoft.Barcode.BarcodeInfo   
Imports Vintasoft.Imaging   
   
''' <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
        Using 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 VintasoftBitmap = writer.GetBarcodeAsVintasoftBitmap()   
                ' 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 VintasoftBitmap = writer.GetBarcodeAsVintasoftBitmap()   
                    ' 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 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 "Constructors"   
   
    ''' <summary>
    ''' Initializes a new instance of the <see cref="Code39Checksum256Symbology" /> class.
    ''' </summary>
    Public Sub New()   
        MyBase.New(BarcodeType.Code39, "Code39 CH256")   
    End Sub   
   
    #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.BarcodeType   
        ' 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 Vintasoft.Barcode.SymbologySubsets;
using Vintasoft.Barcode;
using Vintasoft.Barcode.BarcodeInfo;
using Vintasoft.Imaging;

/// <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
        using (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 (VintasoftBitmap imageWithCode39BarcodeWithChecksum = writer.GetBarcodeAsVintasoftBitmap())
            {
                // 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 (VintasoftBitmap imageWithCode39Barcode = writer.GetBarcodeAsVintasoftBitmap())
                {
                    // 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 Constructors

    /// <summary>
    /// Initializes a new instance of the <see cref="Code39Checksum256Symbology" /> class.
    /// </summary>
    public Code39Checksum256Symbology()
        :base(BarcodeType.Code39, "Code39 CH256")
    {
    }
    
    #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.BarcodeType;
        // 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.
*/