Camera Preview in Android 7

Question

I use the direct camera API for backward compatibility. The camera view itself is slightly overlapping with the image, and my surfaceChanged does this:

camera.setPreviewCallback((data, arg1) -> LiveView.this.invalidate()); camera.setPreviewDisplay(mHolder); camera.startPreview(); 

which works great on all old devices. I set the preview size to the largest available size previously in surfaceCreated . However, on Android 7.1 it suddenly turns black (on the Nexus 6 and Moto X Play, perhaps on others - like this on different devices). SurfaceView itself SurfaceView highlighted in the Layout Inspector ( willNotDraw = true ), but VISIBLE (and hardware acceleration). Oddly enough, I can still take photos, an event without a preview, and the data in the preview callback contains an image.

At the same time, I get the next magazine

 E/mm-camera: mct_pipeline_send_ctrl_events: Send Set Parm events E/QCamera2HWI: static void* qcamera::QCameraCbNotifier::cbNotifyRoutine(void*) : cb message type 32768 not enabled! E/QCamera2HWI: static void* qcamera::QCameraCbNotifier::cbNotifyRoutine(void*) : cb message type 32768 not enabled! D/QCameraParameters: setSnapshotSkipHint: preview hint 3 fps 15.019738 

Has anyone else had a completely black image in Android 7? Are there any easy fixes? (How to draw data content directly?)

Answer 1

A black screen will appear, since you do not have camera resolution on your Android 7 device

Select settings-> apps-> select your application-> permissions-> Enable camera resolution and check

You can also handle this inside your code.

Add the following permission to your manifest

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

To request permission, you can call this.

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

To check permission to access the camera

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

Now callback if the user has performed any action.

 @Override public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) { switch (requestCode) { case MY_PERMISSIONS_REQUEST_CAMERA: { Log.i("Camera", "G : " + grantResults[0]); // If request is cancelled, the result arrays are empty. if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) { // permission was granted, yay! Do the // contacts-related task you need to do. openCamera(); } else { // permission denied, boo! Disable the // functionality that depends on this permission. if (ActivityCompat.shouldShowRequestPermissionRationale (this, Manifest.permission.CAMERA)) { showAlert(); } else { } } return; } // other 'case' lines to check for other // permissions this app might request } } 

Here is a complete example

  import android.Manifest; import android.app.Activity; import android.app.AlertDialog; import android.content.Context; import android.content.DialogInterface; import android.content.Intent; import android.content.SharedPreferences; import android.content.pm.PackageManager; import android.net.Uri; import android.os.Bundle; import android.provider.Settings; import android.support.v4.app.ActivityCompat; import android.support.v4.content.ContextCompat; import android.support.v7.app.AppCompatActivity; import android.support.v7.widget.Toolbar; public class MainActivity extends AppCompatActivity { public static final int MY_PERMISSIONS_REQUEST_CAMERA = 100; public static final String ALLOW_KEY = "ALLOWED"; public static final String CAMERA_PREF = "camera_pref"; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); setSupportActionBar(toolbar); if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) { if (getFromPref(this, ALLOW_KEY)) { showSettingsAlert(); } else if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) { // Should we show an explanation? if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.CAMERA)) { showAlert(); } else { // No explanation needed, we can request the permission. ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, MY_PERMISSIONS_REQUEST_CAMERA); } } } else { openCamera(); } } public static void saveToPreferences(Context context, String key, Boolean allowed) { SharedPreferences myPrefs = context.getSharedPreferences (CAMERA_PREF, Context.MODE_PRIVATE); SharedPreferences.Editor prefsEditor = myPrefs.edit(); prefsEditor.putBoolean(key, allowed); prefsEditor.commit(); } public static Boolean getFromPref(Context context, String key) { SharedPreferences myPrefs = context.getSharedPreferences (CAMERA_PREF, Context.MODE_PRIVATE); return (myPrefs.getBoolean(key, false)); } private void showAlert() { AlertDialog alertDialog = new AlertDialog.Builder(this).create(); alertDialog.setTitle("Alert"); alertDialog.setMessage("App needs to access the Camera."); alertDialog.setButton(AlertDialog.BUTTON_NEGATIVE, "DONT ALLOW", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { dialog.dismiss(); finish(); } }); alertDialog.setButton(AlertDialog.BUTTON_POSITIVE, "ALLOW", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { dialog.dismiss(); ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.CAMERA}, MY_PERMISSIONS_REQUEST_CAMERA); } }); alertDialog.show(); } private void showSettingsAlert() { AlertDialog alertDialog = new AlertDialog.Builder(this).create(); alertDialog.setTitle("Alert"); alertDialog.setMessage("App needs to access the Camera."); alertDialog.setButton(AlertDialog.BUTTON_NEGATIVE, "DONT ALLOW", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { dialog.dismiss(); //finish(); } }); alertDialog.setButton(AlertDialog.BUTTON_POSITIVE, "SETTINGS", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { dialog.dismiss(); startInstalledAppDetailsActivity(MainActivity.this); } }); alertDialog.show(); } @Override public void onRequestPermissionsResult (int requestCode, String permissions[], int[] grantResults) { switch (requestCode) { case MY_PERMISSIONS_REQUEST_CAMERA: { for (int i = 0, len = permissions.length; i < len; i++) { String permission = permissions[i]; if (grantResults[i] == PackageManager.PERMISSION_DENIED) { boolean showRationale = ActivityCompat.shouldShowRequestPermissionRationale (this, permission); if (showRationale) { showAlert(); } else if (!showRationale) { // user denied flagging NEVER ASK AGAIN // you can either enable some fall back, // disable features of your app // or open another dialog explaining // again the permission and directing to // the app setting saveToPreferences(MainActivity.this, ALLOW_KEY, true); } } } } // other 'case' lines to check for other // permissions this app might request } } public static void startInstalledAppDetailsActivity(final Activity context) { if (context == null) { return; } final Intent i = new Intent(); i.setAction(Settings.ACTION_APPLICATION_DETAILS_SETTINGS); i.addCategory(Intent.CATEGORY_DEFAULT); i.setData(Uri.parse("package:" + context.getPackageName())); i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); i.addFlags(Intent.FLAG_ACTIVITY_NO_HISTORY); i.addFlags(Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS); context.startActivity(i); } private void openCamera() { Intent intent = new Intent("android.media.action.IMAGE_CAPTURE"); startActivity(intent); } } 

Answer 2

As mentioned in @apk, a black screen appears because you are not processing permissions in your code. If you are working with targetSdkVersion 23 (or higher), you will have to request permission from the user at runtime.

The previous comment explains to you how to resolve it using SDK operations directly, but I prefer to use a large third-party library for these cases: Karumi / Dexter

Answer 3

Check camera permissions at runtime

If resolution is not allowed, a blank screen will appear on the camera.

for more details:

https://inthecheesefactory.com/blog/things-you-need-to-know-about-android-m-permission-developer-edition/en