C# ZKTeco Fingerprint Scanner Implementation (ZK4500, SLK20M, SLK20R, ZK9500 )

Connecting to a device requires the index of the device you wish to connect to. The index can be retrieved by calling the GetDeviceCount method from the above section.

Besides establishing a connection  to the device, you need to initialize a few more things like the fingerprint image height and width with can be obtained by calling the GetParameters method. It is recommended to use the  image size parameters  provided by the device instead of using a static height and width.

public void ConnectDevice(int deviceIndex)
{
    int openDeviceCallBackCode = fpInstance.OpenDevice(deviceIndex);

    if (zkfp.ZKFP_ERR_OK != openDeviceCallBackCode)
    {
        // Unable to connect with the device
        return;
    }

    RegisterCount = 0;
    regTempLen = 0;
    iFid = 1;

    for (int i = 0; i < REGISTER_FINGER_COUNT; i++)
    {
        RegTmps[i] = new byte[2048];
    }

    byte[] paramValue = new byte[4];


    // Retrieve the fingerprint image width 
    int size = 4;
    fpInstance.GetParameters(PARAM_CODE_IMAGE_WIDTH, paramValue, ref size);
    zkfp2.ByteArray2Int(paramValue, ref mfpWidth);

    // Retrieve the fingerprint image height
    size = 4;
    fpInstance.GetParameters(PARAM_CODE_IMAGE_HEIGHT, paramValue, ref size);
    zkfp2.ByteArray2Int(paramValue, ref mfpHeight);

    FPBuffer = new byte[mfpWidth * mfpHeight];
    
    // Create a thread to retrieve any new fingerprint and handle device events
    captureThread = new Thread(new ThreadStart(DoCapture));
    captureThread.IsBackground = true;
    captureThread.Start();

    bIsTimeToDie = false;

}

Registration is generally a 3 step process. i.e The current user must input his same fingerprint 3 times continuously in order to be successfully enrolled.

private void RegistrationCase()
{
    int fid = 0, score = 0;
    int returnValue = fpInstance.Identify(CapTmp, ref fid, ref score);

    if (zkfp.ZKFP_ERR_OK == returnValue)
    {
        // Remove the previous fingerprint from memory
        int deleteCode = fpInstance.DelRegTemplate(fid);   
        if (deleteCode != zkfp.ZKFP_ERR_OK)
        {
            // The fingerprint is already registered
            return;
        }
    }

    // Check if the user has enterd the fingerprint 3 times or not
    if (RegisterCount > 0 && fpInstance.Match(CapTmp, RegTmps[RegisterCount - 1]) <= 0)
    {
        return;
    }

    Array.Copy(CapTmp, RegTmps[RegisterCount], cbCapTmp);

    RegisterCount++;
    if (RegisterCount >= REGISTER_FINGER_COUNT)
    {

        RegisterCount = 0;
        // Generate a fingerprint template by the combination of 3 successfully fingerprint acquisition
        returnValue = fpInstance.GenerateRegTemplate(RegTmps[0], RegTmps[1], RegTmps[2], RegTmp, ref regTempLen);

        if (zkfp.ZKFP_ERR_OK == returnValue)
        {

            // LOAD TEMPLATE TO MEMORY
            returnValue = fpInstance.AddRegTemplate(iFid, RegTmp);        

            if (zkfp.ZKFP_ERR_OK == returnValue)
            {
                string fingerPrintTemplate = string.Empty;
                zkfp.Blob2Base64String(RegTmp, regTempLen, ref fingerPrintTemplate);

                // ******** fingerPrintTemplate holdes the successfully enrolled fingerprint *******

            }
            else
            {
                // Failed to add template
            }

        }
        else
        {
            // Unable to enroll due to some reason
        }

        return;
    }
    else
    {
        // Requires 3 fingerprints to successfully enroll
        // Ask for the same fingerprint 2 more times
        int remainingCont = REGISTER_FINGER_COUNT - RegisterCount;
    }

}