Fix Android M (6.0) Camera Runtime Persmission

app/build.gradle

@@ -33,7 +33,7 @@ dependencies {
     compile 'com.android.support:appcompat-v7:23.1.1'
     compile 'com.android.support:design:23.1.1'
     compile 'com.journeyapps:zxing-android-embedded:3.0.3@aar'
-    compile 'com.google.zxing:core:3.2.0'
+    compile 'com.google.zxing:core:3.2.1'
     compile 'commons-codec:commons-codec:1.5'
 
     androidTestCompile 'com.android.support:support-annotations:23.1.1'

app/src/main/java/net/bierbaumer/otp_authenticator/MainActivity.java

@@ -1,14 +1,19 @@
 package net.bierbaumer.otp_authenticator;
 
+import android.Manifest;
 import android.animation.ObjectAnimator;
 import android.app.Activity;
 import android.app.AlertDialog;
 import android.content.DialogInterface;
 import android.content.Intent;
+import android.content.pm.PackageManager;
 import android.os.Bundle;
 import android.os.Handler;
+import android.support.annotation.NonNull;
 import android.support.design.widget.FloatingActionButton;
 import android.support.design.widget.Snackbar;
+import android.support.v4.app.ActivityCompat;
+import android.support.v4.content.ContextCompat;
 import android.support.v7.app.AppCompatActivity;
 import android.support.v7.widget.Toolbar;
 import android.view.ActionMode;
@@ -38,6 +43,49 @@ public class MainActivity extends AppCompatActivity implements  ActionMode.Callb
     private Handler handler;
     private Runnable handlerTask;
 
+    private static final int PERMISSIONS_REQUEST_CAMERA = 42;
+
+    private void doScanQRCode(){
+        new IntentIntegrator(MainActivity.this)
+                .setCaptureActivity(CaptureActivityAnyOrientation.class)
+                .setOrientationLocked(false)
+                .initiateScan();
+    }
+
+    private void scanQRCode(){
+        // check Android 6 permission
+        if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) == PackageManager.PERMISSION_GRANTED) {
+            doScanQRCode();
+        } else {
+            ActivityCompat.requestPermissions(this,
+                    new String[]{Manifest.permission.CAMERA}, PERMISSIONS_REQUEST_CAMERA);
+        }
+    }
+
+    @Override
+    public void onRequestPermissionsResult(int requestCode, @NonNull String permissions[], @NonNull int[] grantResults) {
+       if(requestCode == PERMISSIONS_REQUEST_CAMERA) {
+           if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
+               // permission was granted
+               doScanQRCode();
+           } else {
+               Snackbar.make(fab, R.string.msg_camera_permission, Snackbar.LENGTH_LONG).setCallback(new Snackbar.Callback() {
+                   @Override
+                   public void onDismissed(Snackbar snackbar, int event) {
+                       super.onDismissed(snackbar, event);
+
+                       if (entries.isEmpty()) {
+                           showNoAccount();
+                       }
+                   }
+               }).show();
+           }
+       }
+       else {
+           super.onRequestPermissionsResult(requestCode, permissions, grantResults);
+       }
+    }
+
     private Entry nextSelection = null;
     private void showNoAccount(){
         Snackbar noAccountSnackbar = Snackbar.make(fab, R.string.no_accounts, Snackbar.LENGTH_INDEFINITE)
@@ -50,13 +98,6 @@ public class MainActivity extends AppCompatActivity implements  ActionMode.Callb
         noAccountSnackbar.show();
     }
 
-    private void scanQRCode(){
-        new IntentIntegrator(MainActivity.this)
-                .setCaptureActivity(CaptureActivityAnyOrientation.class)
-                .setOrientationLocked(false)
-                .initiateScan();
-    }
-
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);

app/src/main/res/values/strings.xml

@@ -16,4 +16,5 @@
     <string name="button_remove">Remove</string>
     <string name="alert_rename">Rename</string>
     <string name="alert_remove">"Remove "</string>
+    <string name="msg_camera_permission">Camera permission not granted</string>
 </resources>