How to scan QRCode in android

Question

I found a tutorial on how to scan a barcode. But in my application I have to scan a QR code. How can I a scan QR code in Android?

Answer 1

One way is using the AppCompatActivity and ZXingScannerView.ResultHandler interface.

import android.annotation.SuppressLint;
import android.content.Context;
import android.content.Intent;
import android.hardware.Camera;
import android.hardware.camera2.CameraAccessException;
import android.hardware.camera2.CameraCharacteristics;
import android.hardware.camera2.CameraManager;
import android.os.Build;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.RelativeLayout;;

import com.android.volley.VolleyError;
import com.example.team.merchant.functional.Request;
import com.example.team.merchant.functional.ResponseListener;
import com.google.zxing.Result;

import me.dm7.barcodescanner.zxing.ZXingScannerView;

/**
 * Created by Prakhar on 5/16/2016.
 */
public class MerchantScannerActivity extends AppCompatActivity implements ZXingScannerView.ResultHandler {
    private ZXingScannerView mScannerView;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        RelativeLayout relativeLayout = new RelativeLayout(this);

        RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(60, 60);
        params.setMargins(0, 50, 50, 0);
        params.addRule(RelativeLayout.ALIGN_PARENT_RIGHT, RelativeLayout.TRUE);


        Button switchCamera = new Button(this); //declare a button in layout for camera change option
        switchCamera.setLayoutParams(params);
        switchCamera.setBackgroundResource(R.drawable.switch_camera);
        relativeLayout.addView(switchCamera);
        final int i = getFrontCameraId();
        if (i == -1) {
            switchCamera.setVisibility(View.GONE);
        }


        mScannerView = new ZXingScannerView(this);   // Programmatically initialize the scanner view
        relativeLayout.addView(mScannerView);

        setContentView(relativeLayout);
        final int[] id = {0};
        switchCamera.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mScannerView.stopCamera();
                if (id[0] % 2 == 0) {
                    mScannerView.startCamera(i);
                } else {
                    mScannerView.startCamera();
                }
                id[0]++;
            }
        });

        mScannerView.setResultHandler(this);// Register ourselves as a handler for scan results.

        mScannerView.startCamera();         // Start camera


    }

    @SuppressLint("NewApi")
    int getFrontCameraId() {
        if (Build.VERSION.SDK_INT < 22) {
            Camera.CameraInfo ci = new Camera.CameraInfo();
            for (int i = 0; i < Camera.getNumberOfCameras(); i++) {
                Camera.getCameraInfo(i, ci);
                if (ci.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) return i;
            }
        } else {
            try {
                CameraManager cManager = (CameraManager) getApplicationContext()
                        .getSystemService(Context.CAMERA_SERVICE);
                String[] cameraId = cManager.getCameraIdList();
                for (int j = 0; j < cameraId.length; j++) {
                    CameraCharacteristics characteristics = cManager.getCameraCharacteristics(cameraId[j]);
                    int cOrientation = characteristics.get(CameraCharacteristics.LENS_FACING);
                    if (cOrientation == CameraCharacteristics.LENS_FACING_FRONT)
                        return Integer.parseInt(cameraId[j]);
                }
            } catch (CameraAccessException e) {
                e.printStackTrace();
            }
        }
        return -1; // No front-facing camera found
    }

    @Override
    public void onPause() {
        super.onPause();
        mScannerView.stopCamera();           // Stop camera on pause
    }

    @Override
    public void handleResult(Result rawResult) {
       // rawResult.getText()
       // handle your result here
       // handle exceptions here
    }
}

Other can be used in fragments accordingly.

import android.Manifest;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.ActivityCompat;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AlertDialog;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import com.google.zxing.ResultPoint;
import com.journeyapps.barcodescanner.BarcodeCallback;
import com.journeyapps.barcodescanner.BarcodeResult;
import com.journeyapps.barcodescanner.CompoundBarcodeView;


/**
 * Created by Prakhar on 3/8/2016.
 */
public class PayWithQrCodeScannerFragment extends Fragment {

    private static final int PERMISSION_REQUEST_CAMERA = 23;
    public static CompoundBarcodeView barcodeScannerView;
    public static BarcodeCallback callback;



    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.paywithqrcodescannerfragment, container, false);

        barcodeScannerView = (CompoundBarcodeView) view.findViewById(R.id.zxing_barcode_scanner);


        callback = new BarcodeCallback() {
            @Override
            public void barcodeResult(BarcodeResult result) {
                    // handle result and exceptions here
            }
        return view;
    }

    /**
     * Check if the device's camera has a Flashlight.
     *
     * @return true if there is Flashlight, otherwise false.
     */
    private boolean hasFlash() {
        return getActivity().getApplicationContext().getPackageManager()
                .hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH);
    }


    @Override
    public void onResume() {
        super.onResume();
        if (android.os.Build.VERSION.SDK_INT < 23) {
            barcodeScannerView.resume();
        }
    }


    @Override
    public void onPause() {
        super.onPause();
        if (android.os.Build.VERSION.SDK_INT < 23) {
            barcodeScannerView.pause();
        }
    }

}

Use below written in layout XML file to placeholder the scanner

<com.journeyapps.barcodescanner.CompoundBarcodeView
            android:id="@+id/zxing_barcode_scanner"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:zxing_preview_scaling_strategy="centerCrop"
            app:zxing_use_texture_view="false" />

Build.gradle

compile 'com.journeyapps:zxing-android-embedded:3.2.0@aar'
compile 'com.google.zxing:core:3.2.1'