Mobile Vision barcodeScanner: Why does SurfaceView not update CameraSource?

Question

I have been following the following tutorial, which uses the mobile vision api to create a barcode/qr code scanner. Although I have entered the exact code that it said to (At least I think), the camera feed from the cameraSource.

I had added some extra code in the process to see if it would make a difference, but it still has not. The issue is that when I start the app, the SurfaceView which should display the CAMERA_FACING_BACK feed, but it is plain black instead. If you could please tell me why the feed does not show up, and if there is any, the code that needs to change, it will be much appreciated.

MainActivity.java:

package com.example.neekondev.barcodeshortened;

import android.Manifest;
import android.content.pm.PackageManager;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
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;

import static com.google.android.gms.vision.CameraSource.CAMERA_FACING_BACK;
import static com.google.android.gms.vision.CameraSource.CAMERA_FACING_FRONT;

public class MainActivity extends AppCompatActivity {

    SurfaceView cameraView;
    TextView barcodeInfo;

    BarcodeDetector barcodeDetector;
    CameraSource cameraSource;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        cameraView = (SurfaceView) findViewById(R.id.camera_view);
        barcodeInfo = (TextView) findViewById(R.id.code_info);
        barcodeDetector =
                new BarcodeDetector.Builder(this)
                        .setBarcodeFormats(Barcode.CODE_39 | Barcode.CODE_93 | Barcode.CODE_128)
                        .build();

        cameraSource = new CameraSource
                .Builder(this, barcodeDetector)
                .setRequestedPreviewSize(640, 480)
                .setRequestedFps(20.0f)
                .setFacing(CAMERA_FACING_BACK)
                .build();
        cameraView.getHolder().addCallback(new SurfaceHolder.Callback() {
            @Override
            public void surfaceCreated(SurfaceHolder holder) {
                try {
                    if (ActivityCompat.checkSelfPermission(getApplicationContext(),
                            Manifest.permission.CAMERA) !=
                            PackageManager.PERMISSION_GRANTED) {
                        // TODO: Consider calling
                        //    ActivityCompat#requestPermissions
                        // here to request the missing permissions, and then overriding
                        //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                        //                                          int[] grantResults)
                        // to handle the case where the user grants the permission. See the documentation
                        // for ActivityCompat#requestPermissions for more details.
                        return;
                    }
                    cameraSource.start(cameraView.getHolder());
                } catch (IOException ie) {
                    Log.e("CAMERA SOURCE", ie.getMessage());
                }
            }

            @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<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() {    // Use the post method of the TextView
                        public void run() {
                            barcodeInfo.setText(    // Update the TextView
                                    barcodes.valueAt(0).displayValue
                            );
                        }
                    });
                }
            }
        });
    }
}

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:id="@+id/activity_main"
    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"
    tools:context="com.example.neekondev.barcodeshortened.MainActivity">

    <SurfaceView
        android:layout_width="640px"
        android:layout_height="480px"
        android:layout_centerVertical="true"
        android:layout_alignParentLeft="true"
        android:id="@+id/camera_view"
        />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/code_info"
        android:layout_toRightOf="@+id/camera_view"
        android:textSize="20sp"
        android:layout_marginLeft="16dp"
        android:text="Nothing yet..."
        android:layout_alignParentTop="true"
        />
</RelativeLayout>

manifest.xml:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.neekondev.barcodeshortened">

    <meta-data android:name="com.google.android.gms.vision.DEPENDENCIES" android:value="barcode"/>

    <uses-permission android:name="android.permission.CAMERA" />
    <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>

Answer 1

Never Mind, I figured this out on my own, though I think that others may ask the same question after the tutorial, so I will show you what went wrong. You see, although I declared the permission in the Manifest, the android.permissions.CAMERA is a "High Risk Permission", which means that the user needs to manually consent to it before it may be implimented. Because I never made a permissions dialog to request it from the user directly, all code using the camera permission could not be executed, thus giving us the blank screen vs the camera's feed. A simple fix to this is to go into settings and allow the permission there, but the following code can be used instead, conveniently requesting the camera permission with a dialog box;

import android.Manifest;
import android.content.Intent;
import android.content.pm.ActivityInfo;
import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.media.Image;
import android.os.Bundle;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.util.SparseArray;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.RelativeLayout;
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 com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;

import java.io.IOException;
import java.text.DateFormat;
import java.util.ArrayList;
import java.util.Date;

import static junit.framework.Assert.assertNotNull;

public class MainActivity
        extends AppCompatActivity {

    FirebaseDatabase database;
    DatabaseReference myRef;

    SurfaceView cameraView;
    TextView barcodeInfo;

    BarcodeDetector barcodeDetector;
    CameraSource cameraSource;

    private static final int CAMERA_PERMISSION_CAMERA = 0x000000;
    public static boolean position = false;
    //Camera cam;
    //Camera.Parameters p;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        setRequestedOrientation(ActivityInfo
                .SCREEN_ORIENTATION_PORTRAIT);
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        if (ContextCompat.checkSelfPermission(MainActivity
                .this,
                Manifest
                        .permission
                        .CAMERA)
                != PackageManager
                .PERMISSION_GRANTED) {

            // Should we show an explanation?
            if (ActivityCompat.shouldShowRequestPermissionRationale(MainActivity
                    .this,
                    Manifest
                            .permission
                            .CAMERA)) {

                // Show an explanation to the user *asynchronously* -- don't block
                // this thread waiting for the user's response! After the user
                // sees the explanation, try again to request the permission.

            } else {

                // No explanation needed, we can request the permission.

                ActivityCompat.requestPermissions(MainActivity
                        .this,
                        new String[]{Manifest.permission
                                .CAMERA},
                        CAMERA_PERMISSION_CAMERA);

                // CAMERA_PERMISSION_CAMERA is an
                // app-defined int constant. The callback method gets the
                // result of the request.
            }
        }

        cameraView = (SurfaceView) findViewById(R
                .id
                .camera_view);
        barcodeInfo = (TextView) findViewById(R
                .id
                .code_info);

        MainActivity
                .this
                .getPackageManager()
                .hasSystemFeature
                        (PackageManager
                                .FEATURE_CAMERA_FLASH);

        barcodeDetector =
                new BarcodeDetector.Builder(getApplicationContext())
                        .setBarcodeFormats(Barcode.ALL_FORMATS)
                        .build();

        cameraSource = new CameraSource
                .Builder(getApplicationContext(), barcodeDetector)
                .setFacing(CameraSource.CAMERA_FACING_BACK)
                .setRequestedFps(35.0f)
                .setRequestedPreviewSize(960, 960)
                .setAutoFocusEnabled(true)
                .build();

        //setupButtons();


        cameraView.getHolder().addCallback(new SurfaceHolder
                .Callback() {
            @Override
            public void surfaceCreated(SurfaceHolder holder) {
                try {
                    if (ActivityCompat.checkSelfPermission(MainActivity.this,
                            Manifest.permission.CAMERA)
                            != PackageManager.PERMISSION_GRANTED) {
                        //      TODO: CONSIDER CALLING
                        //ActivityCompat#requestPermissions
                        // here to request the missing permissions, and then overriding
                        //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                        //                                          int[] grantResults)
                        // to handle the case where the user grants the permission. See the documentation
                        // for ActivityCompat#requestPermissions for more details.


                        return;
                    }
                    cameraSource.start(cameraView
                            .getHolder());
                } catch (IOException ie) {
                    Log.e("CAMERA SOURCE", ie
                            .getMessage());
                }
            }

            @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<Barcode>()
        {
            @Override
            public void release() {
            }

            @Override
            public void receiveDetections(Detector.Detections<Barcode> detections)
            {
                final SparseArray<Barcode> barcodes = detections.getDetectedItems();
                database = FirebaseDatabase.getInstance();
                myRef = database
                        .getReference(getTime());
                if (barcodes
                        .size() != 0) {
                    barcodeInfo
                            .post(new Runnable() {    // Use the post method of the TextView
                        public void run() {
                            barcodeInfo.setText(barcodes
                                    .valueAt(0)
                                    .displayValue
                            );
                            myRef.setValue(barcodes
                                    .valueAt(0)
                                    .displayValue
                            );
                        }
                    });
                }
            }
        });
    }
/*
    public void FLASH_ON()
    {
        cam = Camera.open();
        p = cam.getParameters();
        p.setFlashMode(Camera
                .Parameters
                .FLASH_MODE_TORCH);
        cam.setParameters(p);
        cam.startPreview();
    }

    public void FLASH_OFF()
    {cam.stopPreview();
        cam.release();}

    public void setupButtons()
    {
        ImageButton flash = (ImageButton)findViewById(R.id.flash);
        flash.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v)
            {
                if (position == false)
                {
                    FLASH_ON();
                    position = true;
                } if (position == true)
                {
                    FLASH_OFF();
                    position = false;
                }
            }
        });
    }*/

    public String getTime()
    {
        String downToSeconds = DateFormat
                .getDateTimeInstance()
                .format(
                        new Date());
        return downToSeconds;
    }

    @Override
    public void onRequestPermissionsResult(int requestCode,
                                           String permissions[],
                                           int[] grantResults) {
        switch (requestCode) {
            case CAMERA_PERMISSION_CAMERA: {
                // If request is cancelled, the result arrays are empty.
                if (grantResults.length > 0
                        && grantResults[0]
                        == PackageManager
                        .PERMISSION_GRANTED) {

                    Intent startMain = new Intent(MainActivity
                            .this, MainActivity
                            .class);
                    startActivity(startMain);

                } else {
                    if (ContextCompat.checkSelfPermission(MainActivity
                                    .this,
                            Manifest
                                    .permission
                                    .CAMERA)
                            != PackageManager
                            .PERMISSION_GRANTED) {

                        // Should we show an explanation?
                        if (ActivityCompat.shouldShowRequestPermissionRationale(MainActivity
                                        .this,
                                Manifest
                                        .permission
                                        .CAMERA)) {

                            // Show an explanation to the user *asynchronously* -- don't block
                            // this thread waiting for the user's response! After the user
                            // sees the explanation, try again to request the permission.

                        } else {

                            // No explanation needed, we can request the permission.

                            ActivityCompat.requestPermissions(MainActivity
                                            .this,
                                    new String[]{Manifest.permission
                                            .CAMERA},
                                    CAMERA_PERMISSION_CAMERA);

                            // CAMERA_PERMISSION_CAMERA is an
                            // app-defined int constant. The callback method gets the
                            // result of the request.
                        }
                    }
                }
                return;
            }
        }
    }
}

Please excuse some of my server code. I was uploading results to a firebase database as well. The rest is identical though. The layouts have some minor tweaks for scaling, but the rest is the same. Good Luck!