QR/Bar Code Scanner in Android
Implementing a QR code and barcode scanner in an Android app can be done using the Barcode Scanner library provided by Google Mobile Vision. Here’s a step-by-step guide on how to integrate a QR code and barcode scanner into your Android app:
1. Create a New Android Project:
Start by creating a new Android project or open an existing one in Android Studio.
2. Add Google Play Services Dependency:
To use the Barcode Scanner library, add the Google Play Services dependency to your app-level build.gradle file:
implementation 'com.google.android.gms:play-services-vision:20.2.0'Sync your project to download the dependency.
3. Design the User Interface:
Create a layout XML file for your scanner activity. You’ll typically include a SurfaceView or TextureView to display the camera preview and a Button to start the scanning process. Here’s an example layout (activity_scanner.xml):
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".ScannerActivity">
<SurfaceView
android:id="@+id/cameraPreview"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<Button
android:id="@+id/scanButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Scan"
android:layout_centerHorizontal="true"
android:layout_alignParentBottom="true"
android:layout_marginBottom="16dp" />
</RelativeLayout>4. Create the ScannerActivity:
Create a new ScannerActivity or add the scanning functionality to an existing activity. In this activity, you’ll initialize the camera and set up the barcode scanner.
import android.Manifest;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
import com.google.android.gms.vision.CameraSource;
import com.google.android.gms.vision.Detector;
import com.google.android.gms.vision.barcode.Barcode;
import com.google.android.gms.vision.barcode.BarcodeDetector;
import java.io.IOException;
public class ScannerActivity extends AppCompatActivity {
private SurfaceView cameraPreview;
private CameraSource cameraSource;
private Button scanButton;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_scanner);
cameraPreview = findViewById(R.id.cameraPreview);
scanButton = findViewById(R.id.scanButton);
// Initialize the barcode detector
BarcodeDetector barcodeDetector = new BarcodeDetector.Builder(this)
.setBarcodeFormats(Barcode.QR_CODE | Barcode.CODE_128)
.build();
// Initialize the camera source and set the camera preview
cameraSource = new CameraSource.Builder(this, barcodeDetector)
.setRequestedPreviewSize(640, 480)
.setAutoFocusEnabled(true)
.build();
// Set up the scanner callback
barcodeDetector.setProcessor(new Detector.Processor<Barcode>() {
@Override
public void release() {
}
@Override
public void receiveDetections(Detector.Detections<Barcode> detections) {
// Process detected barcodes here
final SparseArray<Barcode> barcodes = detections.getDetectedItems();
if (barcodes.size() > 0) {
// Barcode(s) detected
String barcodeData = barcodes.valueAt(0).displayValue;
// Handle the barcode data as needed
}
}
});
// Set click listener for the scan button
scanButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// Start the camera preview and scanning process
startCamera();
}
});
}
private void startCamera() {
try {
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) == PackageManager.PERMISSION_GRANTED) {
cameraSource.start(cameraPreview.getHolder());
} else {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, 123);
}
} catch (IOException e) {
e.printStackTrace();
}
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (requestCode == 123 && grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
startCamera();
}
}
}5. Request Camera Permission:
The code above requests camera permission when the “Scan” button is clicked. Make sure to add the necessary permissions in your AndroidManifest.xml file:
<uses-permission android:name="android.permission.CAMERA" />6. Handle Scanned Data:
In the receiveDetections method, you can access the scanned barcode data. You can implement the logic to handle the scanned data as needed, such as displaying it in a text view or performing some action based on the data.
7. Test Your Scanner:
Run the app on an Android device with a camera. When you click the “Scan” button, the camera preview will start, and it will attempt to detect QR codes and CODE_128 barcodes. When a valid barcode is detected, you can implement the logic to handle the data.
You’ve integrated a QR code and barcode scanner into your Android app. You can customize the scanner further by modifying the layout and handling scanned data according to your application’s requirements.