Fingerprint scanning with DigitalPersona 4500 reader. How to get captured image and loading events handlers

Question

I'm new to coding with biometric sensors and DLLs in C#. I'm using a DigitalPersona reader UareU 4500. I have read the API documentation and saw the sample program they provided. However, I´m not interested in using the GUI version. I would like to use the API methods. I have searched for examples, but was unable to find any descriptive one. Please help.

My question is how to setup to load the EventHandlers and how to obtain the fingerprint in a bitmap image.

Thank you in advance. Any information or guide is highly appreciate it.

class FingerprintScanning
{
    public DPFP.Capture.Capture fingerprint = new DPFP.Capture.Capture();
    public DPFP.Sample sample = new DPFP.Sample();
    public DPFP.Capture.EventHandler EventHandler;
    public Bitmap picture_result = null;


    public void CaptureFingerprint()
    {
        fingerprint.StartCapture();

        //Events
     EventHandler.OnFingerTouch(fingerprint,fingerprint.ReaderSerialNumber);
 EventHandler.OnComplete(fingerprint,fingerprint.ReaderSerialNumber,sample);

        //Convert to Bitmap
        SampleConversion image = new SampleConversion();
        image.ConvertToPicture(sample, ref picture_result);
        fingerprint.StopCapture();

    }

}

Answer 1

I found the example for using the SDK's API. Sharing here in case anyone needs to implement in projects alike.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace Enrollment
{
/* NOTE: This form is a base for the EnrollmentForm and the VerificationForm,
    All changes in the CaptureForm will be reflected in all its derived forms.
*/
public partial class CaptureForm : Form, DPFP.Capture.EventHandler
{
    public CaptureForm()
    {
        InitializeComponent();
    }

    protected virtual void Init()
    {
        try
        {
            Capturer = new DPFP.Capture.Capture();              // Create a capture operation.

            if ( null != Capturer )
                Capturer.EventHandler = this;                   // Subscribe for capturing events.
            else
                SetPrompt("Can't initiate capture operation!");
        }
        catch
        {               
            MessageBox.Show("Can't initiate capture operation!", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);            
        }
    }

    protected virtual void Process(DPFP.Sample Sample)
    {
        // Draw fingerprint sample image.
        DrawPicture(ConvertSampleToBitmap(Sample));
    }

    protected void Start()
    {
        if (null != Capturer)
        {
            try
            {
                Capturer.StartCapture();
                SetPrompt("Using the fingerprint reader, scan your fingerprint.");
            }
            catch
            {
                SetPrompt("Can't initiate capture!");
            }
        }
    }

    protected void Stop()
    {
        if (null != Capturer)
        {
            try
            {
                Capturer.StopCapture();
            }
            catch
            {
                SetPrompt("Can't terminate capture!");
            }
        }
    }

#region Form Event Handlers:

    private void CaptureForm_Load(object sender, EventArgs e)
    {
        Init();
        Start();                                                // Start capture operation.
    }

    private void CaptureForm_FormClosed(object sender, FormClosedEventArgs e)
    {
        Stop();
    }
#endregion

#region EventHandler Members:

    public void OnComplete(object Capture, string ReaderSerialNumber, DPFP.Sample Sample)
    {
        MakeReport("The fingerprint sample was captured.");
        SetPrompt("Scan the same fingerprint again.");
        Process(Sample);
    }

    public void OnFingerGone(object Capture, string ReaderSerialNumber)
    {
        MakeReport("The finger was removed from the fingerprint reader.");
    }

    public void OnFingerTouch(object Capture, string ReaderSerialNumber)
    {
        MakeReport("The fingerprint reader was touched.");
    }

    public void OnReaderConnect(object Capture, string ReaderSerialNumber)
    {
        MakeReport("The fingerprint reader was connected.");
    }

    public void OnReaderDisconnect(object Capture, string ReaderSerialNumber)
    {
        MakeReport("The fingerprint reader was disconnected.");
    }

    public void OnSampleQuality(object Capture, string ReaderSerialNumber, DPFP.Capture.CaptureFeedback CaptureFeedback)
    {
        if (CaptureFeedback == DPFP.Capture.CaptureFeedback.Good)
            MakeReport("The quality of the fingerprint sample is good.");
        else
            MakeReport("The quality of the fingerprint sample is poor.");
    }
#endregion

    protected Bitmap ConvertSampleToBitmap(DPFP.Sample Sample)
    {
        DPFP.Capture.SampleConversion Convertor = new DPFP.Capture.SampleConversion();  // Create a sample convertor.
        Bitmap bitmap = null;                                                           // TODO: the size doesn't matter
        Convertor.ConvertToPicture(Sample, ref bitmap);                                 // TODO: return bitmap as a result
        return bitmap;
    }

    protected DPFP.FeatureSet ExtractFeatures(DPFP.Sample Sample, DPFP.Processing.DataPurpose Purpose)
    {
        DPFP.Processing.FeatureExtraction Extractor = new DPFP.Processing.FeatureExtraction();  // Create a feature extractor
        DPFP.Capture.CaptureFeedback feedback = DPFP.Capture.CaptureFeedback.None;
        DPFP.FeatureSet features = new DPFP.FeatureSet();
        Extractor.CreateFeatureSet(Sample, Purpose, ref feedback, ref features);            // TODO: return features as a result?
        if (feedback == DPFP.Capture.CaptureFeedback.Good)
            return features;
        else
            return null;
    }

    protected void SetStatus(string status)
    {
        this.Invoke(new Function(delegate() {
            StatusLine.Text = status;
        }));
    }

    protected void SetPrompt(string prompt)
    {
        this.Invoke(new Function(delegate() {
            Prompt.Text = prompt;
        }));
    }
    protected void MakeReport(string message)
    {
        this.Invoke(new Function(delegate() {
            StatusText.AppendText(message + "\r\n");
        }));
    }

    private void DrawPicture(Bitmap bitmap)
    {
        this.Invoke(new Function(delegate() {
        Picture.Image = new Bitmap(bitmap, Picture.Size);   // fit the image 
into the picture box
            }));
        }

        private DPFP.Capture.Capture Capturer;

    }
}