Add runtime permission check for QR Code activity

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/QrCodeCaptureActivity.java

@@ -1,23 +1,31 @@
 /*
  * Copyright (C) 2015 Dominik Schürmann <dominik@dominikschuermann.de>
  *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  *
- *      http://www.apache.org/licenses/LICENSE-2.0
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
  *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 package org.sufficientlysecure.keychain.ui;
 
+import android.Manifest;
+import android.app.Activity;
+import android.content.Intent;
+import android.content.pm.PackageManager;
 import android.os.Bundle;
+import android.support.annotation.NonNull;
+import android.support.v4.app.ActivityCompat;
 import android.support.v4.app.FragmentActivity;
+import android.support.v4.content.ContextCompat;
 import android.view.KeyEvent;
 
 import com.journeyapps.barcodescanner.CaptureManager;
@@ -29,6 +37,8 @@ public class QrCodeCaptureActivity extends FragmentActivity {
     private CaptureManager capture;
     private CompoundBarcodeView barcodeScannerView;
 
+    public static final int MY_PERMISSIONS_REQUEST_CAMERA = 42;
+
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -38,33 +48,87 @@ public class QrCodeCaptureActivity extends FragmentActivity {
         barcodeScannerView = (CompoundBarcodeView) findViewById(R.id.zxing_barcode_scanner);
         barcodeScannerView.setStatusText(getString(R.string.import_qr_code_text));
 
+        if (savedInstanceState != null) {
+            init(barcodeScannerView, getIntent(), savedInstanceState);
+        }
+
+        // check Android 6 permission
+        if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA)
+                == PackageManager.PERMISSION_GRANTED) {
+            init(barcodeScannerView, getIntent(), null);
+        } else {
+
+//            // Should we show an explanation?
+//            if (ActivityCompat.shouldShowRequestPermissionRationale(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 {
+
+            ActivityCompat.requestPermissions(this,
+                    new String[]{Manifest.permission.CAMERA},
+                    MY_PERMISSIONS_REQUEST_CAMERA);
+
+//            }
+        }
+    }
+
+    private void init(CompoundBarcodeView barcodeScannerView, Intent intent, Bundle savedInstanceState) {
         capture = new CaptureManager(this, barcodeScannerView);
-        capture.initializeFromIntent(getIntent(), savedInstanceState);
+        capture.initializeFromIntent(intent, savedInstanceState);
         capture.decode();
     }
 
+    @Override
+    public void onRequestPermissionsResult(int requestCode, @NonNull String permissions[],
+                                           @NonNull int[] grantResults) {
+        switch (requestCode) {
+            case MY_PERMISSIONS_REQUEST_CAMERA: {
+                if (grantResults.length > 0
+                        && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
+                    // permission was granted
+                    init(barcodeScannerView, getIntent(), null);
+                } else {
+                    setResult(Activity.RESULT_CANCELED);
+                    finish();
+                }
+            }
+        }
+    }
+
     @Override
     protected void onResume() {
         super.onResume();
-        capture.onResume();
+        if (capture != null) {
+            capture.onResume();
+        }
     }
 
     @Override
     protected void onPause() {
         super.onPause();
-        capture.onPause();
+        if (capture != null) {
+            capture.onPause();
+        }
     }
 
     @Override
     protected void onDestroy() {
         super.onDestroy();
-        capture.onDestroy();
+        if (capture != null) {
+            capture.onDestroy();
+        }
     }
 
     @Override
     protected void onSaveInstanceState(Bundle outState) {
         super.onSaveInstanceState(outState);
-        capture.onSaveInstanceState(outState);
+        if (capture != null) {
+            capture.onSaveInstanceState(outState);
+        }
     }
 
     @Override