VintaSoft Barcode .NET SDK 15.0: Руководство для .NET разработчика
В этом разделе
    Как использовать пользовательскую контрольную сумму в штрих-коде?
    В этом разделе
    SDK позволяет указать метод, который проверяет и помечает найденный штрих-код как хороший или плохой штрих-код (свойство Vintasoft.Barcode.ReaderSettings.VerifyBarcodeMethod).


    Пример: Вот пример, который показывает, как добавить пользовательскую контрольную сумму (с основанием 1000) в штрих-код Code 39 и проверить контрольную сумму при распознавании штрих-кода.
    public static void TestCode39Barcode(string value)
    {
        // create the barcode writer
        using (Vintasoft.Barcode.BarcodeWriter writer = new Vintasoft.Barcode.BarcodeWriter())
        {
            // set barcode writer settings
            writer.Settings.Barcode = Vintasoft.Barcode.BarcodeType.Code39;
            writer.Settings.Value = value;
            writer.Settings.ValueVisible = false;
    
            // get image of barcode without checksum
            using (Vintasoft.Imaging.VintasoftBitmap barcodeWithoutChecksumImage = writer.GetBarcodeAsVintasoftBitmap())
            {
                // set barcode writer settings
                writer.Settings.Value = value + GenerateChecksum(value);
    
                // get image of barcode with custom checksum
                using (Vintasoft.Imaging.VintasoftBitmap barcodeWithMyChecksumImage = writer.GetBarcodeAsVintasoftBitmap())
                {
                    // create the barcode reader
                    Vintasoft.Barcode.BarcodeReader reader = new Vintasoft.Barcode.BarcodeReader();
    
                    // set barcode reader settings
                    reader.Settings.ScanBarcodeTypes = Vintasoft.Barcode.BarcodeType.Code39;
                    reader.Settings.MinConfidence = 100;
                    reader.Settings.AutomaticRecognition = true;
                    reader.Settings.ExpectedBarcodes = 1;
    
                    // set delegate to a method that verifies the barcode value
                    reader.Settings.VerifyBarcodeMethod = VerifyBarcodeMethod;
    
                    // read barcodes from image of barcode without checksum - barcodes will not be found
                    Vintasoft.Barcode.IBarcodeInfo[] infos = reader.ReadBarcodes(barcodeWithoutChecksumImage);
                    System.Console.WriteLine("Scan (NoChecksum):");
                    for (int i = 0; i < infos.Length; i++)
                        System.Console.WriteLine(infos[i].Value);
    
                    // read barcodes from image of barcode with checksum - one barcode will be found
                    infos = reader.ReadBarcodes(barcodeWithMyChecksumImage);
                    System.Console.WriteLine("Scan (MyChecksum):");
                    for (int i = 0; i < infos.Length; i++)
                        System.Console.WriteLine(infos[i].Value);
                }
            }
        }
    }
    
    /// <summary>
    /// Generates the checksum at base 1000.
    /// </summary>
    static string GenerateChecksum(string value)
    {
        int checkSum = 0;
        for (int i = 0; i < value.Length; i++)
        {
            checkSum += ((byte)value[i]) * i;
            checkSum %= 1000;
        }
        // result - [000..999]
        return checkSum.ToString().PadLeft(3, '0');
    }
    
    /// <summary>
    /// Verifies the barcode value.
    /// </summary>
    static void VerifyBarcodeMethod(Vintasoft.Barcode.BarcodeReader reader, Vintasoft.Barcode.IBarcodeInfo barcodeInfo)
    {
        if (TestChecksum(barcodeInfo.Value))
            barcodeInfo.Confidence = 100;
        else
            barcodeInfo.Confidence = 0;
    }
    
    /// <summary>
    /// Tests checksum in barcode value.
    /// </summary>
    static bool TestChecksum(string barcodeValue)
    {
        if (barcodeValue.Length < 4)
            return false;
        string value = barcodeValue.Substring(0, barcodeValue.Length - 3);
        string readChecksum = barcodeValue.Substring(barcodeValue.Length - 3);
        return readChecksum == GenerateChecksum(value);
    }
    
    Public Shared Sub TestCode39Barcode(value As String)
        ' create the barcode writer
        Using writer As New Vintasoft.Barcode.BarcodeWriter()
            ' set barcode writer settings
            writer.Settings.Barcode = Vintasoft.Barcode.BarcodeType.Code39
            writer.Settings.Value = value
            writer.Settings.ValueVisible = False
    
            ' get image of barcode without checksum
            Using barcodeWithoutChecksumImage As Vintasoft.Imaging.VintasoftBitmap = writer.GetBarcodeAsVintasoftBitmap()
                ' set barcode writer settings
                writer.Settings.Value = value & GenerateChecksum(value)
    
                ' get image of barcode with custom checksum
                Using barcodeWithMyChecksumImage As Vintasoft.Imaging.VintasoftBitmap = writer.GetBarcodeAsVintasoftBitmap()
                    ' create the barcode reader
                    Dim reader As New Vintasoft.Barcode.BarcodeReader()
    
                    ' set barcode reader settings
                    reader.Settings.ScanBarcodeTypes = Vintasoft.Barcode.BarcodeType.Code39
                    reader.Settings.MinConfidence = 100
                    reader.Settings.AutomaticRecognition = True
                    reader.Settings.ExpectedBarcodes = 1
    
                    ' set delegate to a method that verifies the barcode value
                    reader.Settings.VerifyBarcodeMethod = AddressOf VerifyBarcodeMethod
    
                    ' read barcodes from image of barcode without checksum - barcodes will not be found
                    Dim infos As Vintasoft.Barcode.IBarcodeInfo() = reader.ReadBarcodes(barcodeWithoutChecksumImage)
                    System.Console.WriteLine("Scan (NoChecksum):")
                    For i As Integer = 0 To infos.Length - 1
                        System.Console.WriteLine(infos(i).Value)
                    Next
    
                    ' read barcodes from image of barcode with checksum - one barcode will be found
                    infos = reader.ReadBarcodes(barcodeWithMyChecksumImage)
                    System.Console.WriteLine("Scan (MyChecksum):")
                    For i As Integer = 0 To infos.Length - 1
                        System.Console.WriteLine(infos(i).Value)
                    Next
                End Using
            End Using
        End Using
    End Sub
    
    ''' <summary>
    ''' Generates the checksum at base 1000.
    ''' </summary>
    Private Shared Function GenerateChecksum(value As String) As String
        Dim checkSum As Integer = 0
        For i As Integer = 0 To value.Length - 1
            checkSum += CByte(AscW(value(i))) * i
            checkSum = checkSum Mod 1000
        Next
        ' result - [000..999]
        Return checkSum.ToString().PadLeft(3, "0"C)
    End Function
    
    ''' <summary>
    ''' Verifies the barcode value.
    ''' </summary>
    Private Shared Sub VerifyBarcodeMethod(reader As Vintasoft.Barcode.BarcodeReader, barcodeInfo As Vintasoft.Barcode.IBarcodeInfo)
        If TestChecksum(barcodeInfo.Value) Then
            barcodeInfo.Confidence = 100
        Else
            barcodeInfo.Confidence = 0
        End If
    End Sub
    
    ''' <summary>
    ''' Tests checksum in barcode value.
    ''' </summary>
    Private Shared Function TestChecksum(barcodeValue As String) As Boolean
        If barcodeValue.Length < 4 Then
            Return False
        End If
        Dim value As String = barcodeValue.Substring(0, barcodeValue.Length - 3)
        Dim readChecksum As String = barcodeValue.Substring(barcodeValue.Length - 3)
        Return readChecksum = GenerateChecksum(value)
    End Function