scanning QR code using ZXING library

ashwini gupta

27 November 2017

What is QR Code?

QR is an acronym for Quick Response. It’s a smarter version of the barcode, and it was originally developed in Japan for the automotive industry. Machines can read QR codes more quickly than barcodes, and QR codes can store more data in less space too.

Implementing QR Scanner by using ZXING Library- it provides easiest way to implement a QR code Scanner for developers.

following steps to use this library.

add the dependency to app level build.gradle

compile 'com.dlazaro66.qrcodereaderview:qrcodereaderview:2.0.3'

1

compile 'com.dlazaro66.qrcodereaderview:qrcodereaderview:2.0.3'

Add a “QRCodeReaderView” in the layout editor like you actually do with a button for example.
In your onCreate method, you can find the view, as usual, using findViewById() function.

Create an Activity which implements,onQRCodeReadListener and let implements required methods or set a onQRCodeReadListener to the QRCodeReaderView object.

 <com.dlazaro66.qrcodereaderview.QRCodeReaderView
        android:id="@+id/qrdecoderview"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

<com.dlazaro66.qrcodereaderview.QRCodeReaderView

android:id="@+id/qrdecoderview"

android:layout_width="match_parent"

android:layout_height="match_parent" />

Make sure you have camera permissions in order to use the library.
Start & Stop camera preview in onPause() and onResume() overriden methods.
You can place widgets or views over QRDecoderView.

public class QRDecoderActivity extends Activity implements OnQRCodeReadListener {
	private QRCodeReaderView qrCodeReaderView;

	@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_decoder);
        
        qrCodeReaderView = (QRCodeReaderView) findViewById(R.id.qrdecoderview);
        qrCodeReaderView.setOnQRCodeReadListener(this);

    	  // Use this function to enable/disable decoding
        qrCodeReaderView.setQRDecodingEnabled(true);

        // Use this function to change the autofocus interval (default is 5 secs)
        qrCodeReaderView.setAutofocusInterval(2000L);

        // Use this function to enable/disable Torch
        qrCodeReaderView.setTorchEnabled(true);

        // Use this function to set front camera preview
        qrCodeReaderView.setFrontCamera();

        // Use this function to set back camera preview
        qrCodeReaderView.setBackCamera();
    }

    // Called when a QR is decoded
    // "text" : the text encoded in QR
    // "points" : points where QR control points are placed in View
	@Override
	public void onQRCodeRead(String text, PointF[] points) {
	// add here your source code with scanning code
	}
    
	@Override
	protected void onResume() {
		super.onResume();
		qrCodeReaderView.startCamera();
	}
	
	@Override
	protected void onPause() {
		super.onPause();
		qrCodeReaderView.stopCamera();
	}
}

public class QRDecoderActivity extends Activity implements OnQRCodeReadListener {

private QRCodeReaderView qrCodeReaderView;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_decoder);

qrCodeReaderView = (QRCodeReaderView) findViewById(R.id.qrdecoderview);

qrCodeReaderView.setOnQRCodeReadListener(this);

// Use this function to enable/disable decoding

qrCodeReaderView.setQRDecodingEnabled(true);

// Use this function to change the autofocus interval (default is 5 secs)

qrCodeReaderView.setAutofocusInterval(2000L);

// Use this function to enable/disable Torch

qrCodeReaderView.setTorchEnabled(true);

// Use this function to set front camera preview

qrCodeReaderView.setFrontCamera();

// Use this function to set back camera preview

qrCodeReaderView.setBackCamera();

}

// Called when a QR is decoded

// "text" : the text encoded in QR

// "points" : points where QR control points are placed in View

@Override

public void onQRCodeRead(String text, PointF[] points) {

// add here your source code with scanning code

}

@Override

protected void onResume() {

super.onResume();

qrCodeReaderView.startCamera();

}

@Override

protected void onPause() {

super.onPause();

qrCodeReaderView.stopCamera();

}

References: https://github.com/dlazaro66/QRCodeReaderView