Steps to Build the QR Code Scanner

1. Include Required Libraries:

• OpenCV: For accessing the webcam and capturing frames.
• ZXing (Zebra Crossing): For decoding the QR code from the image.

2. Set Up Webcam Capture:

You’ll use OpenCV to stream the video feed from the webcam. Below is an example of how to capture webcam frames and display them in a JPanel.

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You’ll use OpenCV to stream the video feed from the webcam. Below is an example of how to capture webcam frames and display them in a JPanel.

import org.opencv.core.Mat;
import org.opencv.videoio.VideoCapture;
import javax.swing.*;
import java.awt.*;
import java.awt.image.BufferedImage;

public class WebcamCapture extends JPanel {
    private BufferedImage image;

    public WebcamCapture() {
        Thread cameraThread = new Thread(() -> {
            VideoCapture camera = new VideoCapture(0);
            Mat frame = new Mat();
            while (camera.isOpened()) {
                if (camera.read(frame)) {
                    image = convertToBufferedImage(frame);
                    repaint();
                }
            }
        });
        cameraThread.start();
    }

    private BufferedImage convertToBufferedImage(Mat frame) {
        // Convert Mat (OpenCV format) to BufferedImage
        // Implement this conversion logic
        return new BufferedImage(...);
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        if (image != null) {
            g.drawImage(image, 0, 0, null);
        }
    }
}

3. Decode the QR Code:

Use the ZXing library to decode the QR code from the frames captured by the webcam.

import com.google.zxing.*;
import com.google.zxing.common.HybridBinarizer;
import java.awt.image.BufferedImage;

public class QRCodeDecoder {
    public String decodeQRCode(BufferedImage image) {
        try {
            LuminanceSource source = new BufferedImageLuminanceSource(image);
            BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));
            Result result = new MultiFormatReader().decode(bitmap);
            return result.getText();
        } catch (Exception e) {
            return "QR Code not found";
        }
    }
}

4. Set Up the Main Application:

Combine the webcam stream and QR code decoding logic in a Java Swing UI.

import javax.swing.*;

public class MainApp {
    public static void main(String[] args) {
        JFrame frame = new JFrame("QR Code Scanner");
        WebcamCapture webcamCapture = new WebcamCapture();
        frame.add(webcamCapture);
        frame.setSize(640, 480);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);

        // Add logic to decode QR codes from the webcam feed periodically
        // and display the decoded text in the frame (e.g., JLabel or console output).
    }
}

5. Required Libraries

1. ZXing (Zebra Crossing): For QR code decoding.
2. OpenCV: For webcam access and frame capturing.

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5.1 Adding Libraries to Your NetBeans Project

Step 1: Download Libraries

• ZXing Core: Download from Maven Repository – ZXing Core.
• OpenCV:
  • Download OpenCV Java bindings from the official OpenCV website.
  • Extract the ZIP file and locate the opencv-xxx.jar file (inside build/java) and the native libraries (.dll, .so, or .dylib files for your OS).

Step 2: Add Libraries to Your Project

1. Open your project in NetBeans.
2. Right-click on your project in the Projects tab and select Properties.
3. Go to the Libraries section.
4. Click Add JAR/Folder and select:
   • zxing-core-3.x.jar (replace 3.x with the version you downloaded).
   • opencv-xxx.jar (replace xxx with the OpenCV version).

Step 3: Configure OpenCV Native Libraries

1. Ensure the native OpenCV files (e.g., .dll, .so) are in your project folder or somewhere accessible.
2. Add a VM option to your project:

In the Run category of the project properties, add the following under VM Options

-Djava.library.path="path/to/opencv/native/libraries"

Replace path/to/opencv/native/libraries with the location of the OpenCV native files.

6. Dependency Versions

• ZXing Core: Use the latest stable version (e.g., 3.5.2).
• OpenCV: Use the latest Java version (e.g., 4.x).

7. Testing:

1. Ensure the webcam is connected.
2. Run the application to display a live webcam feed.
3. Hold a QR code in front of the camera. Decoded text will be displayed in the console or UI (implement a JLabel for better user feedback).