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>
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.CAMERAis 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;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!