Stop listening to key agreement connections when leaving fragment

Also don't liberate screen orientation when backing out of adding a contact nearby

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddNearbyContactActivity.java

@@ -103,7 +103,8 @@ public class AddNearbyContactActivity extends BriarActivity
 	@Override
 	public void onBackPressed() {
 		if (viewModel.getState().getValue() instanceof Failed) {
-			// re-create this activity when going back in failed state
+			// Re-create this activity when going back in failed state.
+			// This will also re-create the ViewModel, so we start fresh.
 			Intent i = new Intent(this, AddNearbyContactActivity.class);
 			i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
 			startActivity(i);

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddNearbyContactErrorFragment.java

@@ -15,8 +15,11 @@ import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.util.UiUtils;
 
+import javax.inject.Inject;
+
 import androidx.annotation.Nullable;
 import androidx.fragment.app.FragmentActivity;
+import androidx.lifecycle.ViewModelProvider;
 
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
 import static android.view.View.GONE;
@@ -30,6 +33,11 @@ public class AddNearbyContactErrorFragment extends BaseFragment {
 			AddNearbyContactErrorFragment.class.getName();
 	private static final String ERROR_MSG = "errorMessage";
 
+	@Inject
+	ViewModelProvider.Factory viewModelFactory;
+
+	private AddNearbyContactViewModel viewModel;
+
 	public static AddNearbyContactErrorFragment newInstance(String errorMsg) {
 		AddNearbyContactErrorFragment f = new AddNearbyContactErrorFragment();
 		Bundle args = new Bundle();
@@ -46,6 +54,8 @@ public class AddNearbyContactErrorFragment extends BaseFragment {
 	@Override
 	public void injectFragment(ActivityComponent component) {
 		component.inject(this);
+		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
+				.get(AddNearbyContactViewModel.class);
 	}
 
 	@Nullable
@@ -81,6 +91,15 @@ public class AddNearbyContactErrorFragment extends BaseFragment {
 		return v;
 	}
 
+	@Override
+	public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
+		super.onViewCreated(view, savedInstanceState);
+		// We don't do this in AddNearbyContactFragment#onDestroy()
+		// because it gets called when creating AddNearbyContactFragment
+		// in landscape orientation to force portrait orientation.
+		viewModel.stopListening();
+	}
+
 	private void triggerFeedback() {
 		UiUtils.triggerFeedback(requireContext());
 		finish();

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddNearbyContactFragment.java

@@ -31,7 +31,6 @@ import androidx.annotation.UiThread;
 import androidx.lifecycle.ViewModelProvider;
 
 import static android.content.pm.ActivityInfo.SCREEN_ORIENTATION_NOSENSOR;
-import static android.content.pm.ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED;
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
 import static android.view.ViewGroup.LayoutParams.MATCH_PARENT;
@@ -86,23 +85,19 @@ public class AddNearbyContactFragment extends BaseFragment
 	public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
 		super.onViewCreated(view, savedInstanceState);
 		cameraView = view.findViewById(R.id.camera_view);
+		cameraView.setPreviewConsumer(viewModel.getQrCodeDecoder());
 		cameraOverlay = view.findViewById(R.id.camera_overlay);
 		statusView = view.findViewById(R.id.status_container);
 		status = view.findViewById(R.id.connect_status);
 		qrCodeView = view.findViewById(R.id.qr_code_view);
 		qrCodeView.setFullscreenListener(this);
 
+		requireActivity().setRequestedOrientation(SCREEN_ORIENTATION_NOSENSOR);
+
 		viewModel.getState().observe(getViewLifecycleOwner(),
 				this::onAddContactStateChanged);
 	}
 
-	@Override
-	public void onActivityCreated(@Nullable Bundle savedInstanceState) {
-		super.onActivityCreated(savedInstanceState);
-		requireActivity().setRequestedOrientation(SCREEN_ORIENTATION_NOSENSOR);
-		cameraView.setPreviewConsumer(viewModel.getQrCodeDecoder());
-	}
-
 	@Override
 	public void onStart() {
 		super.onStart();
@@ -123,13 +118,6 @@ public class AddNearbyContactFragment extends BaseFragment
 		}
 	}
 
-	@Override
-	public void onDestroy() {
-		requireActivity()
-				.setRequestedOrientation(SCREEN_ORIENTATION_UNSPECIFIED);
-		super.onDestroy();
-	}
-
 	@Override
 	public void setFullscreen(boolean fullscreen) {
 		LinearLayout.LayoutParams statusParams, qrCodeParams;

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddNearbyContactIntroFragment.java

@@ -78,6 +78,15 @@ public class AddNearbyContactIntroFragment extends BaseFragment {
 		return v;
 	}
 
+	@Override
+	public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
+		super.onViewCreated(view, savedInstanceState);
+		// We don't do this in AddNearbyContactFragment#onDestroy()
+		// because it gets called when creating AddNearbyContactFragment
+		// in landscape orientation to force portrait orientation.
+		viewModel.stopListening();
+	}
+
 	@Override
 	public void onStart() {
 		super.onStart();

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddNearbyContactViewModel.java

@@ -314,10 +314,13 @@ class AddNearbyContactViewModel extends AndroidViewModel
 	}
 
 	@UiThread
-	private void stopListening() {
+	void stopListening() {
 		KeyAgreementTask oldTask = task;
 		ioExecutor.execute(() -> {
-			if (oldTask != null) oldTask.stopListening();
+			if (oldTask != null) {
+				oldTask.stopListening();
+				task = null;
+			}
 		});
 	}