detector.isOperational() always false on android

Question

I'm using the new google plays service: Barcode detector, for this porposue I'm following this tutorial : https://search-codelabs.appspot.com/codelabs/bar-codes

But when I run the application on my real device(Asus Nexus 7), the text view of the app always is showing me "Couldn't set up the detector" and i don't know how to make it work >< ...

Here some code for fast debugging:

public class DecoderBar extends Activity implements View.OnClickListener{

private TextView  txt;
private ImageView img;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.layout_decoder);

    Button b = (Button) findViewById(R.id.button);
    txt = (TextView) findViewById(R.id.txtContent);
    img = (ImageView) findViewById(R.id.imgview);

    b.setOnClickListener(this);
}

// [...]

@Override
public void onClick(View v) {

    Bitmap myBitmap = BitmapFactory.decodeResource(getApplicationContext().getResources(),R.drawable.popi);
    img.setImageBitmap(myBitmap);

    BarcodeDetector detector = new BarcodeDetector.Builder(getApplicationContext())
            .setBarcodeFormats(Barcode.DATA_MATRIX | Barcode.QR_CODE)
            .build();

    if(!detector.isOperational()){
        // Always show this message, so, never is operational!
        txt.setText("Could not set up the detector!");
        return;
    }

    Frame frame = new Frame.Builder().setBitmap(myBitmap).build();
    SparseArray<Barcode> barcodes = detector.detect(frame);

    Barcode thisCode = barcodes.valueAt(0);
    txt.setText(thisCode.rawValue);
}
}

Answer 1

It looks like the first time barcode detector is used on each device, some download is done by Google Play Services. Here is the link:

https://developers.google.com/vision/multi-tracker-tutorial

And this is the excerpt:

The first time that an app using barcode and/or face APIs is installed on a device, GMS will download a libraries to the device in order to do barcode and face detection. Usually this is done by the installer before the app is run for the first time.

Answer 2

I had this problem now. You can't update the Google Play Services. After I used the same as on the tutorial it works.

compile 'com.google.android.gms:play-services:7.8+'

Answer 3

Here is what was my case. I was using BarcodeDetector for decoding QR codes from imported images. On 4 my testing devices it was working fine. On one was not reading anything from bitmap. I thought this might be incompatibility with android 5.0 but this was not the case. After hours of investigation I finally noticed that detector.isOperational(); returns false. The reason was:

The first time that an app using barcode and/or face APIs is installed on a device, GMS will download a libraries to the device in order to do barcode and face detection. Usually this is done by the installer before the app is run for the first time.

I had wi-fi off on that testing device. After turning it on and relaunching app, detector became operational and started decoding bitmaps.

Answer 4

To use the API, it's necessary to have internet connection, I had connection to my ADSL but not resolved DNS. Fixing that problem make my app works