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Implementing Barcode API – Barcode Scanner for Android
QR Code scanner or Barcode scanner for android features are present in many apps to read some useful data. In this tutorial, we’ll be discussing and implementing the Barcode API present in the Google Mobile Vision API.
Barcode Scanner for Android
With the introduction of Google Vision API, implementing Barcode API in an application has got a lot easier for developers. Following are the major formats that the Vision API supports.
- 1D barcodes: EAN-13, EAN-8, UPC-A, UPC-E, Code-39, Code-93, Code-128, ITF, Codabar
- 2D barcodes: QR Code, Data Matrix, PDF-417, AZTEC
Barcodes can scan things ranging from URL, Contact info to Geolocation, WIFI, Driver license IDs. QR Code is the more popular format and is commonly seen in many applications. Below, we’ll be developing an application that scans the QR Code value from a bitmap image as well as detects QR Code through a camera and perform the relevant actions.
Implementing Barcode API – Configuring Android Studio for Barcode Library
Add the following inside the build.gradle file.
implementation 'com.google.android.gms:play-services-vision:11.8.0'
Add the following inside the AndroidManifest.xml file application tag to enable barcode detection in your application.
<meta-data
android:name="com.google.android.gms.vision.DEPENDENCIES"
android:value="barcode" />
Implementing Barcode API – QR Code Scanner from Image
The code for the activity_main.xml layout file is given below.
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="https://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin">
<Button
android:id="@+id/btnTakePicture"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:text="@string/take_barcode_picture" />
<Button
android:id="@+id/btnScanBarcode"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/btnTakePicture"
android:layout_centerHorizontal="true"
android:layout_marginTop="@dimen/activity_horizontal_margin"
android:text="@string/scan_barcode" />
</RelativeLayout>
The code for the MainActivity.java is given below.
package com.journaldev.barcodevisionapi;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
Button btnTakePicture, btnScanBarcode;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initViews();
}
private void initViews() {
btnTakePicture = findViewById(R.id.btnTakePicture);
btnScanBarcode = findViewById(R.id.btnScanBarcode);
btnTakePicture.setOnClickListener(this);
btnScanBarcode.setOnClickListener(this);
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btnTakePicture:
startActivity(new Intent(MainActivity.this, PictureBarcodeActivity.class));
break;
case R.id.btnScanBarcode:
startActivity(new Intent(MainActivity.this, ScannedBarcodeActivity.class));
break;
}
}
}
The MainActivity.java contains two buttons. The first launches an Activity that scans for a QR Code in the bitmap image captured from the camera and returns the data present in the QR Code(if any). The second scans for the QRCode and detects them in real time. Before we move onto the business logic of the application, we need to add the following permissions to the AndroidManifest.xml file.
<uses-feature
android:name="android.hardware.camera"
android:required="true" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera.autofocus" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.INTERNET" />
To share and access the files created by other applications we need to add the following provider tag inside our application tag in the AndroidManifest.xml file.
<provider
android:name="android.support.v4.content.FileProvider"
android:authorities="${applicationId}.provider"
android:exported="false"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="@xml/provider_paths" />
</provider>
This is required for retrieving the image captured by the camera in our QR code scanner for android application. Let’s start with the first one namely the PictureBarcodeActivity.java. The code for the xml layout activity_barcode_picture.xml is given below.
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="https://schemas.android.com/apk/res/android"
xmlns:tools="https://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin">
<ImageView
android:id="@+id/imageView"
android:layout_width="150dp"
android:layout_height="150dp"
android:layout_centerHorizontal="true"
android:src="@mipmap/journaldev_logo" />
<TextView
android:id="@+id/txtResultsHeader"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/imageView"
android:layout_centerHorizontal="true"
android:text="Results"
android:textSize="18sp"
android:textStyle="bold" />
<TextView
android:id="@+id/txtResultsBody"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/txtResultsHeader"
android:layout_centerHorizontal="true"
android:layout_marginTop="@dimen/activity_horizontal_margin"
android:gravity="center" />
<Button
android:id="@+id/btnOpenCamera"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="@dimen/activity_horizontal_margin"
android:layout_marginTop="@dimen/activity_horizontal_margin"
android:text="@string/open_camera" />
</RelativeLayout>
The code for the PictureCodeActivity.java class is given below.
package com.journaldev.barcodevisionapi;
import android.Manifest;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.FileProvider;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.util.SparseArray;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import com.google.android.gms.vision.Frame;
import com.google.android.gms.vision.barcode.Barcode;
import com.google.android.gms.vision.barcode.BarcodeDetector;
import java.io.File;
import java.io.FileNotFoundException;
public class PictureBarcodeActivity extends AppCompatActivity implements View.OnClickListener {
Button btnOpenCamera;
TextView txtResultBody;
private BarcodeDetector detector;
private Uri imageUri;
private static final int REQUEST_CAMERA_PERMISSION = 200;
private static final int CAMERA_REQUEST = 101;
private static final String TAG = "API123";
private static final String SAVED_INSTANCE_URI = "uri";
private static final String SAVED_INSTANCE_RESULT = "result";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_barcode_picture);
initViews();
if (savedInstanceState != null) {
if (imageUri != null) {
imageUri = Uri.parse(savedInstanceState.getString(SAVED_INSTANCE_URI));
txtResultBody.setText(savedInstanceState.getString(SAVED_INSTANCE_RESULT));
}
}
detector = new BarcodeDetector.Builder(getApplicationContext())
.setBarcodeFormats(Barcode.DATA_MATRIX | Barcode.QR_CODE)
.build();
if (!detector.isOperational()) {
txtResultBody.setText("Detector initialisation failed");
return;
}
}
private void initViews() {
txtResultBody = findViewById(R.id.txtResultsBody);
btnOpenCamera = findViewById(R.id.btnTakePicture);
txtResultBody = findViewById(R.id.txtResultsBody);
btnOpenCamera.setOnClickListener(this);
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btnTakePicture:
ActivityCompat.requestPermissions(PictureBarcodeActivity.this, new
String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE, Manifest.permission.CAMERA}, REQUEST_CAMERA_PERMISSION);
break;
}
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
switch (requestCode) {
case REQUEST_CAMERA_PERMISSION:
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED && grantResults[1] == PackageManager.PERMISSION_GRANTED) {
takeBarcodePicture();
} else {
Toast.makeText(getApplicationContext(), "Permission Denied!", Toast.LENGTH_SHORT).show();
}
}
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == CAMERA_REQUEST && resultCode == RESULT_OK) {
launchMediaScanIntent();
try {
Bitmap bitmap = decodeBitmapUri(this, imageUri);
if (detector.isOperational() && bitmap != null) {
Frame frame = new Frame.Builder().setBitmap(bitmap).build();
SparseArray barcodes = detector.detect(frame);
for (int index = 0; index < barcodes.size(); index++) {
Barcode code = barcodes.valueAt(index);
txtResultBody.setText(txtResultBody.getText() + "\n" + code.displayValue + "\n");
int type = barcodes.valueAt(index).valueFormat;
switch (type) {
case Barcode.CONTACT_INFO:
Log.i(TAG, code.contactInfo.title);
break;
case Barcode.EMAIL:
Log.i(TAG, code.displayValue);
break;
case Barcode.ISBN:
Log.i(TAG, code.rawValue);
break;
case Barcode.PHONE:
Log.i(TAG, code.phone.number);
break;
case Barcode.PRODUCT:
Log.i(TAG, code.rawValue);
break;
case Barcode.SMS:
Log.i(TAG, code.sms.message);
break;
case Barcode.TEXT:
Log.i(TAG, code.displayValue);
break;
case Barcode.URL:
Log.i(TAG, "url: " + code.displayValue);
break;
case Barcode.WIFI:
Log.i(TAG, code.wifi.ssid);
break;
case Barcode.GEO:
Log.i(TAG, code.geoPoint.lat + ":" + code.geoPoint.lng);
break;
case Barcode.CALENDAR_EVENT:
Log.i(TAG, code.calendarEvent.description);
break;
case Barcode.DRIVER_LICENSE:
Log.i(TAG, code.driverLicense.licenseNumber);
break;
default:
Log.i(TAG, code.rawValue);
break;
}
}
if (barcodes.size() == 0) {
txtResultBody.setText("No barcode could be detected. Please try again.");
}
} else {
txtResultBody.setText("Detector initialisation failed");
}
} catch (Exception e) {
Toast.makeText(getApplicationContext(), "Failed to load Image", Toast.LENGTH_SHORT)
.show();
Log.e(TAG, e.toString());
}
}
}
private void takeBarcodePicture() {
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
File photo = new File(Environment.getExternalStorageDirectory(), "pic.jpg");
imageUri = FileProvider.getUriForFile(PictureBarcodeActivity.this,
BuildConfig.APPLICATION_ID + ".provider", photo);
intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);
startActivityForResult(intent, CAMERA_REQUEST);
}
@Override
protected void onSaveInstanceState(Bundle outState) {
if (imageUri != null) {
outState.putString(SAVED_INSTANCE_URI, imageUri.toString());
outState.putString(SAVED_INSTANCE_RESULT, txtResultBody.getText().toString());
}
super.onSaveInstanceState(outState);
}
private void launchMediaScanIntent() {
Intent mediaScanIntent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
mediaScanIntent.setData(imageUri);
this.sendBroadcast(mediaScanIntent);
}
private Bitmap decodeBitmapUri(Context ctx, Uri uri) throws FileNotFoundException {
int targetW = 600;
int targetH = 600;
BitmapFactory.Options bmOptions = new BitmapFactory.Options();
bmOptions.inJustDecodeBounds = true;
BitmapFactory.decodeStream(ctx.getContentResolver().openInputStream(uri), null, bmOptions);
int photoW = bmOptions.outWidth;
int photoH = bmOptions.outHeight;
int scaleFactor = Math.min(photoW / targetW, photoH / targetH);
bmOptions.inJustDecodeBounds = false;
bmOptions.inSampleSize = scaleFactor;
return BitmapFactory.decodeStream(ctx.getContentResolver()
.openInputStream(uri), null, bmOptions);
}
}
Few inferences drawn from the above code are given below.
-
- The following code creates a Barcode Detector.
detector = new BarcodeDetector.Builder(getApplicationContext())
.setBarcodeFormats(Barcode.DATA_MATRIX | Barcode.QR_CODE)
.build();
-
- The types of formats to be scanned are set inside the method setBarcodeFormats().
- takeBarcodePicture() function is where the camera is launched. To retrieve the image we use the launchMediaScanIntent() that calls a broadcast Intent to search for the image using the image URI.
- A Frame.Builder is used to create a frame of the Bitmap image. Over the frame, the Barcode detector scans for the possible QR Codes. The following line in the above code creates a Frame out of the Bitmap.
Frame frame = new Frame.Builder().setBitmap(bitmap).build();
-
- We’ve created a SparseArray that’ll contain all possible QR Codes present in the image by invoking the detect() method over the Barcode Detector.
SparseArray<Barcode> barcodes = detector.detect(frame);
-
- To get the format of the QR Code, the valueFormat field is called over the Barcode instance as shown below.
barcodes.valueAt(index).valueFormat
-
- To get the displayed value and the raw values, the following are invoked.
barcodes.valueAt(index).displayValue
barcodes.valueAt(index).rawValue
-
- The relevant value returned is displayed in the TextView. For then one Barcodes in a Bitmap, their values are appended to the current TextView.
The ScannedBarcodeActivity.java class scans for the Barcode through the camera. The code for the layout of the activity_scan_barcode.xml is given below.
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="https://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="@dimen/activity_horizontal_margin">
<SurfaceView
android:id="@+id/surfaceView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_above="@+id/btnAction"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_centerVertical="true" />
<TextView
android:id="@+id/txtBarcodeValue"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_marginLeft="@dimen/activity_horizontal_margin"
android:layout_marginStart="@dimen/activity_horizontal_margin"
android:text="No Barcode Detected"
android:textColor="@android:color/white"
android:textSize="20sp" />
<Button
android:id="@+id/btnAction"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:text="ADD CONTENT IN THE MAIL" />
</RelativeLayout>
Barcode Scanner for Android from Camera
The code for the ScannedBarcodeActivity.java is given below.
package com.journaldev.barcodevisionapi;
import android.Manifest;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.util.SparseArray;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
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 ScannedBarcodeActivity extends AppCompatActivity {
SurfaceView surfaceView;
TextView txtBarcodeValue;
private BarcodeDetector barcodeDetector;
private CameraSource cameraSource;
private static final int REQUEST_CAMERA_PERMISSION = 201;
Button btnAction;
String intentData = "";
boolean isEmail = false;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_scan_barcode);
initViews();
}
private void initViews() {
txtBarcodeValue = findViewById(R.id.txtBarcodeValue);
surfaceView = findViewById(R.id.surfaceView);
btnAction = findViewById(R.id.btnAction);
btnAction.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (intentData.length() > 0) {
if (isEmail)
startActivity(new Intent(ScannedBarcodeActivity.this, EmailActivity.class).putExtra("email_address", intentData));
else {
startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse(intentData)));
}
}
}
});
}
private void initialiseDetectorsAndSources() {
Toast.makeText(getApplicationContext(), "Barcode scanner started", Toast.LENGTH_SHORT).show();
barcodeDetector = new BarcodeDetector.Builder(this)
.setBarcodeFormats(Barcode.ALL_FORMATS)
.build();
cameraSource = new CameraSource.Builder(this, barcodeDetector)
.setRequestedPreviewSize(1920, 1080)
.setAutoFocusEnabled(true) //you should add this feature
.build();
surfaceView.getHolder().addCallback(new SurfaceHolder.Callback() {
@Override
public void surfaceCreated(SurfaceHolder holder) {
try {
if (ActivityCompat.checkSelfPermission(ScannedBarcodeActivity.this, Manifest.permission.CAMERA) == PackageManager.PERMISSION_GRANTED) {
cameraSource.start(surfaceView.getHolder());
} else {
ActivityCompat.requestPermissions(ScannedBarcodeActivity.this, new
String[]{Manifest.permission.CAMERA}, REQUEST_CAMERA_PERMISSION);
}
} catch (IOException e) {
e.printStackTrace();
}
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
cameraSource.stop();
}
});
barcodeDetector.setProcessor(new Detector.Processor() {
@Override
public void release() {
Toast.makeText(getApplicationContext(), "To prevent memory leaks barcode scanner has been stopped", Toast.LENGTH_SHORT).show();
}
@Override
public void receiveDetections(Detector.Detections detections) {
final SparseArray barcodes = detections.getDetectedItems();
if (barcodes.size() != 0) {
txtBarcodeValue.post(new Runnable() {
@Override
public void run() {
if (barcodes.valueAt(0).email != null) {
txtBarcodeValue.removeCallbacks(null);
intentData = barcodes.valueAt(0).email.address;
txtBarcodeValue.setText(intentData);
isEmail = true;
btnAction.setText("ADD CONTENT TO THE MAIL");
} else {
isEmail = false;
btnAction.setText("LAUNCH URL");
intentData = barcodes.valueAt(0).displayValue;
txtBarcodeValue.setText(intentData);
}
}
});
}
}
});
}
@Override
protected void onPause() {
super.onPause();
cameraSource.release();
}
@Override
protected void onResume() {
super.onResume();
initialiseDetectorsAndSources();
}
}
Few inferences drawn from the above code are given below.
SurfaceView is good to display camera preview images as it renders the GUI rapidly. The interface SurfaceHolder.Callback is used to receive information about changes that occur in the surface (in this case, the camera preview). SurfaceHolder.Callback implements three methods:
-
-
- SurfaceChanged: This method is called when the size or the format of the surface changes.
- SurfaceCreated: When, in the first instance, the surface is created, this method is called.
- SurfaceDestroyed: This is called when the surface is destroyed.
-
CameraSource manages the camera in conjunction with an underlying detector. Here SurfaceView is the underlying detector. CameraSource.start() opens the camera and starts sending preview frames to the SurfaceView. CameraSource is created in the following way:
cameraSource = new CameraSource.Builder(this, barcodeDetector)
.setRequestedPreviewSize(1920, 1080)
.setAutoFocusEnabled(true) //you should add this feature
.build();
We’ve assigned a processor on the Barcode Detector using setProcessor(). The interface contains the callback to the method receiveDetections() which receives the QR Code from the camera preview and adds them in the SparseArray.
The value of the QR Code is displayed in the TextView using a Runnable since the Barcodes are detected in a background thread.
In this example, we’ve created two barcodes using the generator. One contains the URL. The second contains an email address. On clicking the button, based on the QR code value detected, we’ll either launch the URL or send an email to the relevant email address detected from the QR Code.
That’s all for QR code scanner project for android using Mobile Vision API.
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