I followed this tutorial on how to build an Android app that can scan QR codes.
Here's the full code. I added the Google Play services using grade like so compile 'com.google.android.gms:play-services:7.8.0'
.
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="bitinvent.io.qrscanner" >
<meta-data android:name="com.google.android.gms.vision.DEPENDENCIES" android:value="barcode"/>
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.CAMERA"/>
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme" >
<activity android:name=".MainActivity" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">
<SurfaceView
android:id="@+id/cameraView"
android:layout_width="640px"
android:layout_height="480px"
android:layout_centerVertical="true"
android:layout_alignParentLeft="true"/>
<TextView
android:id="@+id/infoTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_toRightOf="@+id/cameraView"
android:layout_marginLeft="16dp"
android:text="Nothing to read"
android:textSize="20sp"/>
</RelativeLayout>
MainActivity.java
package bitinvent.io.qrscanner;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.util.SparseArray;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.widget.TextView;
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 MainActivity extends Activity {
private SurfaceView cameraView;
private TextView barcodeInfo;
private CameraSource cameraSource;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
cameraView = (SurfaceView) findViewById(R.id.cameraView);
barcodeInfo = (TextView) findViewById(R.id.infoTextView);
BarcodeDetector detector = new BarcodeDetector.Builder(this).setBarcodeFormats(Barcode.QR_CODE).build();
cameraSource = new CameraSource.Builder(this, detector).setRequestedPreviewSize(640, 480).build();
cameraView.getHolder().addCallback(new SurfaceHolder.Callback() {
@Override
public void surfaceCreated(SurfaceHolder holder) {
try {
cameraSource.start(cameraView.getHolder());
} catch (IOException e) {
Log.e("CAMERA SOURCE", e.getMessage());
}
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
cameraSource.stop();
}
});
detector.setProcessor(new Detector.Processor<Barcode>() {
@Override
public void release() {
}
@Override
public void receiveDetections(Detector.Detections<Barcode> detections) {
final SparseArray<Barcode> barcodes = detections.getDetectedItems();
if (barcodes.size() != 0) {
barcodeInfo.post(new Runnable() {
@Override
public void run() {
barcodeInfo.setText(barcodes.valueAt(0).displayValue);
}
});
}
}
});
}
}
I tested this on a HTC Desire 816 running Android 4.4.2. But it doesn't seem to work. The camera view is active but when pointed at a QR code, it doesn't detect anything. But no errors or crashes occur either.
Am I missing something?
There is an built-in QR code scanner on Android. It works inside Camera app when Google Lens Suggestions is activated. Tested 28th of November, 2018 by Pixel 2 / Android Pie 9.
Finally I got it working in my side. I wanted to share the process and the code that I have right now to implement the QR code scanning in my application. I am not actually answering your question. However, I did not find any good source of help from StackOverflow regarding how can I implement QR code scanning using Google Vision API. I looked into the tutorial that you pointed in your question. However, the tutorial was not very helpful to me either. Hence I am putting down the classes and the steps to implement the QR code scanning in my application.
First of all, you will need some gradle dependencies. So in your build.gradle
file, add the following dependencies.
dependencies {
compile 'com.android.support:design:25.3.1'
compile 'com.google.android.gms:play-services-vision:10.2.1'
}
Then, you need to have the following five classes in your project. I am adding the classes here. Please import the missing classes if necessary.
Now BarcodeCaptureActivity
has a layout which you need to put in your layout
folder as well.
Here's the barcode_capture.xml
layout that you need.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/topLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:keepScreenOn="true"
android:orientation="vertical">
<!-- Do not forget to replace with your package name where the class is located -->
<com.example.yourpackage.camera.CameraSourcePreview
android:id="@+id/preview"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
You will need some strings and an activity entry in manifest for the BarcodeCaptureActivity
. Here are the strings that you need to put in your strings.xml
.
<!-- QR Code related strings -->
<string name="permission_camera_rationale">Access to the camera is needed for detection</string>
<string name="no_camera_permission">This application cannot run because it does not have the camera permission. The application will now exit.</string>
<string name="low_storage_error">Face detector dependencies cannot be downloaded due to low device storage</string>
<string name="ok">OK</string>
And the AndroidManifest.xml
should have a new entry for the BarcodeCaptureActivity
like the following.
<activity
android:name=".util.scanner.BarcodeCaptureActivity"
android:theme="@style/Theme.AppCompat" />
Now your setup is done and you are ready to open your camera for scanning a barcode or QR code. Just call the following initiateScan
function where necessary.
public static final int RC_BARCODE_CAPTURE = 9001;
public void initiateScan() {
Intent intent = new Intent(YourActivity.this, BarcodeCaptureActivity.class);
startActivityForResult(intent, RC_BARCODE_CAPTURE);
}
Please note that, you need to ask for camera permission to the user before you call initiateScan
function. On granting the permission of the camera you will call the initiateScan
function.
The initiateScan
function will open the scanner and then after a successful scan, it will return to the calling Activity
or Fragment
. So you need to have a onActivityResult
function in the calling Activity
or Fragment
.
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == CommonStatusCodes.SUCCESS && requestCode == RC_BARCODE_CAPTURE) {
if (data == null) return;
Barcode barcode = data.getParcelableExtra(BarcodeCaptureActivity.BarcodeObject);
final String scanResult = barcode.displayValue;
if (scanResult == null) return;
doSomethingWithTheScanResult(scanResult);
}
}
Do not forget to add the CAMERA
permission in your AndroidManifest.xml
file as well.
<uses-permission android:name="android.permission.CAMERA" />
Hope that helps for easier integration of QR code scanner using Google Vision API. I have added a github project for a sample QR code scanner application. Please have a look.
Try move the following line
<meta-data android:name="com.google.android.gms.vision.DEPENDENCIES" android:value="barcode" />
to your activity tag in yout manifest right after <intent-filter/>
so it would look like this
<meta-data android:name="com.google.android.gms.vision.DEPENDENCIES" android:value="barcode" />
</activity>
Lemme know if it helps
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