Refactor more code into AddNearbyContactViewModel

thus concentrating the logic there needing less back and forth with the activity

briar-android/src/main/java/org/briarproject/briar/android/activity/RequestCodes.java

@@ -11,7 +11,6 @@ public interface RequestCodes {
 	int REQUEST_RINGTONE = 7;
 	int REQUEST_PERMISSION_CAMERA_LOCATION = 8;
 	int REQUEST_DOZE_WHITELISTING = 9;
-	int REQUEST_BLUETOOTH_DISCOVERABLE = 10;
 	int REQUEST_UNLOCK = 11;
 	int REQUEST_KEYGUARD_UNLOCK = 12;
 	int REQUEST_ATTACH_IMAGE = 13;

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

@@ -1,16 +1,12 @@
 package org.briarproject.briar.android.contact.add.nearby;
 
-import android.content.BroadcastReceiver;
-import android.content.Context;
 import android.content.Intent;
-import android.content.IntentFilter;
 import android.os.Bundle;
 import android.view.MenuItem;
 import android.widget.Toast;
 
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.bramble.api.nullsafety.NullSafety;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
@@ -21,25 +17,25 @@ import org.briarproject.briar.android.contact.add.nearby.AddContactState.Failed;
 import org.briarproject.briar.android.contact.add.nearby.AddNearbyContactViewModel.BluetoothDecision;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.fragment.BaseFragment.BaseFragmentListener;
+import org.briarproject.briar.android.util.RequestBluetoothDiscoverable;
 
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
+import androidx.activity.result.ActivityResultLauncher;
 import androidx.appcompat.widget.Toolbar;
 import androidx.fragment.app.FragmentManager;
 import androidx.lifecycle.ViewModelProvider;
 
 import static android.bluetooth.BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE;
-import static android.bluetooth.BluetoothAdapter.ACTION_SCAN_MODE_CHANGED;
+import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
 import static android.widget.Toast.LENGTH_LONG;
 import static java.util.Objects.requireNonNull;
 import static java.util.logging.Logger.getLogger;
-import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_BLUETOOTH_DISCOVERABLE;
 import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactViewModel.BluetoothDecision.ACCEPTED;
 import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactViewModel.BluetoothDecision.REFUSED;
-import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactViewModel.BluetoothDecision.UNKNOWN;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
@@ -55,14 +51,9 @@ public class AddNearbyContactActivity extends BriarActivity
 	private AddNearbyContactViewModel viewModel;
 	private AddNearbyContactPermissionManager permissionManager;
 
-	/**
-	 * Set to true in onPostResume() and false in onPause(). This prevents the
-	 * QR code fragment from being shown if onRequestPermissionsResult() is
-	 * called while the activity is paused, which could cause a crash due to
-	 * https://issuetracker.google.com/issues/37067655.
-	 */
-	private boolean isResumed = false;
-	private BroadcastReceiver bluetoothReceiver = null;
+	private final ActivityResultLauncher<Integer> bluetoothLauncher =
+			registerForActivityResult(new RequestBluetoothDiscoverable(),
+					this::onBluetoothDiscoverableResult);
 
 	@Override
 	public void injectActivity(ActivityComponent component) {
@@ -79,21 +70,14 @@ public class AddNearbyContactActivity extends BriarActivity
 		setContentView(R.layout.activity_fragment_container_toolbar);
 		Toolbar toolbar = findViewById(R.id.toolbar);
 		setSupportActionBar(toolbar);
-		NullSafety.requireNonNull(getSupportActionBar())
-				.setDisplayHomeAsUpEnabled(true);
+		requireNonNull(getSupportActionBar()).setDisplayHomeAsUpEnabled(true);
 		if (state == null) {
 			showInitialFragment(AddNearbyContactIntroFragment.newInstance());
 		}
-		IntentFilter filter = new IntentFilter(ACTION_SCAN_MODE_CHANGED);
-		bluetoothReceiver = new BluetoothStateReceiver();
-		registerReceiver(bluetoothReceiver, filter);
-		viewModel.getWasContinueClicked().observe(this, clicked -> {
-			if (clicked && permissionManager.checkPermissions()) {
-				showQrCodeFragmentIfAllowed();
-			}
-		});
-		viewModel.getTransportStateChanged().observeEvent(this,
-				t -> showQrCodeFragmentIfAllowed());
+		viewModel.getCheckPermissions().observeEvent(this, check ->
+				permissionManager.checkPermissions()); // never false
+		viewModel.getRequestBluetoothDiscoverable().observeEvent(this, r ->
+				requestBluetoothDiscoverable()); // never false
 		viewModel.getShowQrCodeFragment().observeEvent(this, show -> {
 			if (show) showQrCodeFragment();
 		});
@@ -113,37 +97,23 @@ public class AddNearbyContactActivity extends BriarActivity
 	@Override
 	protected void onPostResume() {
 		super.onPostResume();
-		isResumed = true;
-		// Workaround for
-		// https://code.google.com/p/android/issues/detail?id=190966
-		showQrCodeFragmentIfAllowed();
+		viewModel.setIsActivityResumed(true);
 	}
 
 	@Override
 	protected void onPause() {
 		super.onPause();
-		isResumed = false;
+		viewModel.setIsActivityResumed(false);
 	}
 
-	@Override
-	public void onDestroy() {
-		super.onDestroy();
-		if (bluetoothReceiver != null) unregisterReceiver(bluetoothReceiver);
-	}
-
-	@Override
-	public void onActivityResult(int request, int result,
-			@Nullable Intent data) {
-		if (request == REQUEST_BLUETOOTH_DISCOVERABLE) {
-			if (result == RESULT_CANCELED) {
-				LOG.info("Bluetooth discoverability was refused");
-				viewModel.bluetoothDecision = REFUSED;
-			} else {
-				LOG.info("Bluetooth discoverability was accepted");
-				viewModel.bluetoothDecision = ACCEPTED;
-			}
-			showQrCodeFragmentIfAllowed();
-		} else super.onActivityResult(request, result, data);
+	private void onBluetoothDiscoverableResult(boolean discoverable) {
+		if (discoverable) {
+			LOG.info("Bluetooth discoverability was accepted");
+			viewModel.setBluetoothDecision(ACCEPTED);
+		} else {
+			LOG.info("Bluetooth discoverability was refused");
+			viewModel.setBluetoothDecision(REFUSED);
+		}
 	}
 
 	@Override
@@ -161,14 +131,16 @@ public class AddNearbyContactActivity extends BriarActivity
 		super.onRequestPermissionsResult(requestCode, permissions,
 				grantResults);
 		permissionManager.onRequestPermissionsResult(requestCode, permissions,
-				grantResults, this::showQrCodeFragmentIfAllowed);
+				grantResults, viewModel::showQrCodeFragmentIfAllowed);
 	}
 
 	@Override
 	public void onBackPressed() {
 		if (viewModel.getState().getValue() instanceof Failed) {
-			// finish this activity when going back in failed state
-			supportFinishAfterTransition();
+			// re-create this activity when going back in failed state
+			Intent i = new Intent(this, AddNearbyContactActivity.class);
+			i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
+			startActivity(i);
 		} else {
 			super.onBackPressed();
 		}
@@ -176,41 +148,15 @@ public class AddNearbyContactActivity extends BriarActivity
 
 	private void requestBluetoothDiscoverable() {
 		if (!viewModel.isBluetoothSupported()) {
-			viewModel.bluetoothDecision = BluetoothDecision.NO_ADAPTER;
-			showQrCodeFragmentIfAllowed();
+			viewModel.setBluetoothDecision(BluetoothDecision.NO_ADAPTER);
 		} else {
 			Intent i = new Intent(ACTION_REQUEST_DISCOVERABLE);
 			if (i.resolveActivity(getPackageManager()) != null) {
 				LOG.info("Asking for Bluetooth discoverability");
-				viewModel.bluetoothDecision = BluetoothDecision.WAITING;
-				startActivityForResult(i, REQUEST_BLUETOOTH_DISCOVERABLE);
+				viewModel.setBluetoothDecision(BluetoothDecision.WAITING);
+				bluetoothLauncher.launch(120); // 2min discoverable
 			} else {
-				viewModel.bluetoothDecision = BluetoothDecision.NO_ADAPTER;
-				showQrCodeFragmentIfAllowed();
-			}
-		}
-	}
-
-	@SuppressWarnings("StatementWithEmptyBody")
-	private void showQrCodeFragmentIfAllowed() {
-		boolean continueClicked = // never set to null
-				NullSafety.requireNonNull(
-						viewModel.getWasContinueClicked().getValue());
-		boolean permissionsGranted =
-				permissionManager.areEssentialPermissionsGranted();
-		if (isResumed && continueClicked && permissionsGranted) {
-			if (viewModel.isWifiReady() && viewModel.isBluetoothReady()) {
-				LOG.info("Wifi and Bluetooth are ready");
-				viewModel.startAddingContact();
-			} else {
-				viewModel.enableWifiIfWeShould();
-				if (viewModel.bluetoothDecision == UNKNOWN) {
-					requestBluetoothDiscoverable();
-				} else if (viewModel.bluetoothDecision == REFUSED) {
-					// Ask again when the user clicks "continue"
-				} else {
-					viewModel.enableBluetoothIfWeShould();
-				}
+				viewModel.setBluetoothDecision(BluetoothDecision.NO_ADAPTER);
 			}
 		}
 	}
@@ -233,11 +179,6 @@ public class AddNearbyContactActivity extends BriarActivity
 					((ContactExchangeFinished) state).result;
 			onContactExchangeResult(result);
 		} else if (state instanceof Failed) {
-			// Remove navigation icon, so user can't go back when failed
-			// ErrorFragment will finish or relaunch this activity
-			Toolbar toolbar = findViewById(R.id.toolbar);
-			toolbar.setNavigationIcon(null);
-
 			Boolean qrCodeTooOld = ((Failed) state).qrCodeTooOld;
 			onAddingContactFailed(qrCodeTooOld);
 		}
@@ -286,11 +227,4 @@ public class AddNearbyContactActivity extends BriarActivity
 		showNextFragment(new AddNearbyContactErrorFragment());
 	}
 
-	private class BluetoothStateReceiver extends BroadcastReceiver {
-		@Override
-		public void onReceive(Context context, Intent intent) {
-			LOG.info("Bluetooth scan mode changed");
-			showQrCodeFragmentIfAllowed();
-		}
-	}
 }

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

@@ -171,10 +171,8 @@ public class AddNearbyContactFragment extends BaseFragment
 			status.setText(R.string.waiting_for_contact_to_scan);
 		} else if (state instanceof KeyAgreementStarted) {
 			qrCodeView.setVisibility(INVISIBLE);
-			statusView.setVisibility(VISIBLE);
 			status.setText(R.string.authenticating_with_device);
 		} else if (state instanceof ContactExchangeStarted) {
-			statusView.setVisibility(VISIBLE);
 			status.setText(R.string.exchanging_contact_details);
 		} else if (state instanceof Failed) {
 			// the activity will replace this fragment with an error fragment

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

@@ -1,5 +1,7 @@
 package org.briarproject.briar.android.contact.add.nearby;
 
+import android.content.Context;
+
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.BaseActivity;
 
@@ -11,6 +13,8 @@ import static android.Manifest.permission.ACCESS_FINE_LOCATION;
 import static android.Manifest.permission.CAMERA;
 import static android.content.pm.PackageManager.PERMISSION_GRANTED;
 import static android.os.Build.VERSION.SDK_INT;
+import static androidx.core.app.ActivityCompat.shouldShowRequestPermissionRationale;
+import static androidx.core.content.ContextCompat.checkSelfPermission;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_PERMISSION_CAMERA_LOCATION;
 import static org.briarproject.briar.android.util.UiUtils.getGoToSettingsListener;
 
@@ -37,6 +41,15 @@ class AddNearbyContactPermissionManager {
 		locationPermission = Permission.UNKNOWN;
 	}
 
+	static boolean areEssentialPermissionsGranted(Context ctx,
+			boolean isBluetoothSupported) {
+		int ok = PERMISSION_GRANTED;
+		return checkSelfPermission(ctx, CAMERA) == ok &&
+				(SDK_INT < 23 ||
+						checkSelfPermission(ctx, ACCESS_FINE_LOCATION) == ok ||
+						!isBluetoothSupported);
+	}
+
 	boolean areEssentialPermissionsGranted() {
 		return cameraPermission == Permission.GRANTED &&
 				(SDK_INT < 23 || locationPermission == Permission.GRANTED ||
@@ -147,8 +160,7 @@ class AddNearbyContactPermissionManager {
 	}
 
 	private boolean shouldShowRationale(String permission) {
-		return ActivityCompat
-				.shouldShowRequestPermissionRationale(ctx, permission);
+		return shouldShowRequestPermissionRationale(ctx, permission);
 	}
 
 }

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

@@ -2,6 +2,10 @@ package org.briarproject.briar.android.contact.add.nearby;
 
 import android.app.Application;
 import android.bluetooth.BluetoothAdapter;
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
 import android.graphics.Bitmap;
 import android.util.DisplayMetrics;
 import android.widget.Toast;
@@ -39,6 +43,7 @@ import org.briarproject.bramble.api.plugin.PluginManager;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.plugin.event.TransportStateEvent;
+import org.briarproject.bramble.api.system.AndroidExecutor;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.contact.add.nearby.AddContactState.ContactExchangeFinished;
 import org.briarproject.briar.android.contact.add.nearby.AddContactState.ContactExchangeResult.Error;
@@ -64,6 +69,7 @@ import androidx.lifecycle.AndroidViewModel;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
+import static android.bluetooth.BluetoothAdapter.ACTION_SCAN_MODE_CHANGED;
 import static android.bluetooth.BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE;
 import static android.widget.Toast.LENGTH_LONG;
 import static java.util.Objects.requireNonNull;
@@ -75,6 +81,7 @@ import static org.briarproject.bramble.api.plugin.Plugin.State.DISABLED;
 import static org.briarproject.bramble.api.plugin.Plugin.State.INACTIVE;
 import static org.briarproject.bramble.api.plugin.Plugin.State.STARTING_STOPPING;
 import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactPermissionManager.areEssentialPermissionsGranted;
 import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactViewModel.BluetoothDecision.REFUSED;
 import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactViewModel.BluetoothDecision.UNKNOWN;
 
@@ -116,6 +123,7 @@ class AddNearbyContactViewModel extends AndroidViewModel
 	private static final Charset ISO_8859_1 = Charset.forName("ISO-8859-1");
 
 	private final EventBus eventBus;
+	private final AndroidExecutor androidExecutor;
 	private final Executor ioExecutor;
 	private final PluginManager pluginManager;
 	private final PayloadEncoder payloadEncoder;
@@ -124,28 +132,28 @@ class AddNearbyContactViewModel extends AndroidViewModel
 	private final ContactExchangeManager contactExchangeManager;
 	private final ConnectionManager connectionManager;
 
-	/**
-	 * Set to true when the continue button is clicked, and false when the QR
-	 * code fragment is shown. This prevents the QR code fragment from being
-	 * shown automatically before the continue button has been clicked.
-	 */
-	private final MutableLiveData<Boolean> wasContinueClicked =
-			new MutableLiveData<>(false);
-	private final MutableLiveEvent<Boolean> showQrCodeFragment =
+	private final MutableLiveEvent<Boolean> checkPermissions =
 			new MutableLiveEvent<>();
-	private final MutableLiveEvent<TransportId> transportStateChanged =
+	private final MutableLiveEvent<Boolean> requestBluetoothDiscoverable =
+			new MutableLiveEvent<>();
+	private final MutableLiveEvent<Boolean> showQrCodeFragment =
 			new MutableLiveEvent<>();
 	private final MutableLiveData<AddContactState> state =
 			new MutableLiveData<>();
 
 	final QrCodeDecoder qrCodeDecoder;
+	final BroadcastReceiver bluetoothReceiver = new BluetoothStateReceiver();
 
 	@Nullable
 	private final BluetoothAdapter bt;
 	@Nullable
 	private final Plugin wifiPlugin, bluetoothPlugin;
+
 	// UiThread
-	BluetoothDecision bluetoothDecision = BluetoothDecision.UNKNOWN;
+	private BluetoothDecision bluetoothDecision = BluetoothDecision.UNKNOWN;
+
+	private boolean wasContinueClicked = false;
+	private boolean isActivityResumed = false;
 
 	/**
 	 * Records whether we've enabled the wifi plugin so we don't enable it more
@@ -166,6 +174,7 @@ class AddNearbyContactViewModel extends AndroidViewModel
 	@Inject
 	AddNearbyContactViewModel(Application app,
 			EventBus eventBus,
+			AndroidExecutor androidExecutor,
 			@IoExecutor Executor ioExecutor,
 			PluginManager pluginManager,
 			PayloadEncoder payloadEncoder,
@@ -175,6 +184,7 @@ class AddNearbyContactViewModel extends AndroidViewModel
 			ConnectionManager connectionManager) {
 		super(app);
 		this.eventBus = eventBus;
+		this.androidExecutor = androidExecutor;
 		this.ioExecutor = ioExecutor;
 		this.pluginManager = pluginManager;
 		this.payloadEncoder = payloadEncoder;
@@ -185,13 +195,16 @@ class AddNearbyContactViewModel extends AndroidViewModel
 		bt = BluetoothAdapter.getDefaultAdapter();
 		wifiPlugin = pluginManager.getPlugin(LanTcpConstants.ID);
 		bluetoothPlugin = pluginManager.getPlugin(BluetoothConstants.ID);
-		qrCodeDecoder = new QrCodeDecoder(ioExecutor, this);
+		qrCodeDecoder = new QrCodeDecoder(androidExecutor, ioExecutor, this);
 		eventBus.addListener(this);
+		IntentFilter filter = new IntentFilter(ACTION_SCAN_MODE_CHANGED);
+		getApplication().registerReceiver(bluetoothReceiver, filter);
 	}
 
 	@Override
 	protected void onCleared() {
 		super.onCleared();
+		getApplication().unregisterReceiver(bluetoothReceiver);
 		eventBus.removeListener(this);
 		stopListening();
 	}
@@ -201,7 +214,9 @@ class AddNearbyContactViewModel extends AndroidViewModel
 		if (bluetoothDecision == REFUSED) {
 			bluetoothDecision = UNKNOWN; // Ask again
 		}
-		wasContinueClicked.setValue(true);
+		wasContinueClicked = true;
+		checkPermissions.setEvent(true);
+		showQrCodeFragmentIfAllowed();
 	}
 
 	@UiThread
@@ -266,7 +281,7 @@ class AddNearbyContactViewModel extends AndroidViewModel
 	void startAddingContact() {
 		// If we return to the intro fragment, the continue button needs to be
 		// clicked again before showing the QR code fragment
-		wasContinueClicked.setValue(false);
+		wasContinueClicked = false;
 		// If we return to the intro fragment, ask for Bluetooth
 		// discoverability again before showing the QR code fragment
 		bluetoothDecision = UNKNOWN;
@@ -310,12 +325,12 @@ class AddNearbyContactViewModel extends AndroidViewModel
 				if (LOG.isLoggable(INFO)) {
 					LOG.info("Bluetooth state changed to " + t.getState());
 				}
-				transportStateChanged.setEvent(t.getTransportId());
+				showQrCodeFragmentIfAllowed();
 			} else if (t.getTransportId().equals(LanTcpConstants.ID)) {
 				if (LOG.isLoggable(INFO)) {
 					LOG.info("Wifi state changed to " + t.getState());
 				}
-				transportStateChanged.setEvent(t.getTransportId());
+				showQrCodeFragmentIfAllowed();
 			}
 		} else if (e instanceof KeyAgreementListeningEvent) {
 			LOG.info("KeyAgreementListeningEvent received");
@@ -344,6 +359,28 @@ class AddNearbyContactViewModel extends AndroidViewModel
 		}
 	}
 
+	@SuppressWarnings("StatementWithEmptyBody")
+	@UiThread
+	void showQrCodeFragmentIfAllowed() {
+		boolean permissionsGranted = areEssentialPermissionsGranted(
+				getApplication(), isBluetoothSupported());
+		if (isActivityResumed && wasContinueClicked && permissionsGranted) {
+			if (isWifiReady() && isBluetoothReady()) {
+				LOG.info("Wifi and Bluetooth are ready");
+				startAddingContact();
+			} else {
+				enableWifiIfWeShould();
+				if (bluetoothDecision == UNKNOWN) {
+					requestBluetoothDiscoverable.setEvent(true);
+				} else if (bluetoothDecision == REFUSED) {
+					// Ask again when the user clicks "continue"
+				} else {
+					enableBluetoothIfWeShould();
+				}
+			}
+		}
+	}
+
 	/**
 	 * This sets the QR code by setting the state to KeyAgreementListening.
 	 */
@@ -383,8 +420,8 @@ class AddNearbyContactViewModel extends AndroidViewModel
 			state.postValue(new AddContactState.Failed(e.isTooOld()));
 		} catch (IOException | IllegalArgumentException e) {
 			LOG.log(WARNING, "QR Code Invalid", e);
-			Toast.makeText(getApplication(), R.string.qr_code_invalid,
-					LENGTH_LONG).show();
+			androidExecutor.runOnUiThread(() -> Toast.makeText(getApplication(),
+					R.string.qr_code_invalid, LENGTH_LONG).show());
 			resetPayloadFlags();
 			state.postValue(new AddContactState.Failed());
 		}
@@ -423,6 +460,15 @@ class AddNearbyContactViewModel extends AndroidViewModel
 		});
 	}
 
+	private class BluetoothStateReceiver extends BroadcastReceiver {
+		@UiThread
+		@Override
+		public void onReceive(Context context, Intent intent) {
+			LOG.info("Bluetooth scan mode changed");
+			showQrCodeFragmentIfAllowed();
+		}
+	}
+
 	private void tryToClose(DuplexTransportConnection conn) {
 		try {
 			conn.getReader().dispose(true, true);
@@ -432,16 +478,33 @@ class AddNearbyContactViewModel extends AndroidViewModel
 		}
 	}
 
-	LiveData<Boolean> getWasContinueClicked() {
-		return wasContinueClicked;
+	/**
+	 * Set to true in onPostResume() and false in onPause(). This prevents the
+	 * QR code fragment from being shown if onRequestPermissionsResult() is
+	 * called while the activity is paused, which could cause a crash due to
+	 * https://issuetracker.google.com/issues/37067655.
+	 * TODO check if this is still happening when using new permission requesting
+	 */
+	@UiThread
+	void setIsActivityResumed(boolean resumed) {
+		isActivityResumed = resumed;
+		// Workaround for
+		// https://code.google.com/p/android/issues/detail?id=190966
+		showQrCodeFragmentIfAllowed();
 	}
 
-	/**
-	 * Receives an event when the transport state of the WiFi or Bluetooth
-	 * plugins changes.
-	 */
-	LiveEvent<TransportId> getTransportStateChanged() {
-		return transportStateChanged;
+	@UiThread
+	void setBluetoothDecision(BluetoothDecision decision) {
+		bluetoothDecision = decision;
+		showQrCodeFragmentIfAllowed();
+	}
+
+	LiveEvent<Boolean> getCheckPermissions() {
+		return checkPermissions;
+	}
+
+	LiveEvent<Boolean> getRequestBluetoothDiscoverable() {
+		return requestBluetoothDiscoverable;
 	}
 
 	LiveEvent<Boolean> getShowQrCodeFragment() {

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

@@ -18,6 +18,7 @@ import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.system.AndroidExecutor;
 
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
@@ -35,6 +36,7 @@ class QrCodeDecoder implements PreviewConsumer, PreviewCallback {
 
 	private static final Logger LOG = getLogger(QrCodeDecoder.class.getName());
 
+	private final AndroidExecutor androidExecutor;
 	private final Executor ioExecutor;
 	private final Reader reader = new QRCodeReader();
 	private final ResultCallback callback;
@@ -42,7 +44,9 @@ class QrCodeDecoder implements PreviewConsumer, PreviewCallback {
 	private Camera camera = null;
 	private int cameraIndex = 0;
 
-	QrCodeDecoder(@IoExecutor Executor ioExecutor, ResultCallback callback) {
+	QrCodeDecoder(AndroidExecutor androidExecutor,
+			@IoExecutor Executor ioExecutor, ResultCallback callback) {
+		this.androidExecutor = androidExecutor;
 		this.ioExecutor = ioExecutor;
 		this.callback = callback;
 	}
@@ -104,9 +108,9 @@ class QrCodeDecoder implements PreviewConsumer, PreviewCallback {
 				LOG.warning("Invalid preview frame");
 			} finally {
 				reader.reset();
+				androidExecutor.runOnUiThread(this::askForPreviewFrame);
 			}
 		});
-		askForPreviewFrame();
 	}
 
 	private static BinaryBitmap binarize(byte[] data, int width, int height,

briar-android/src/main/java/org/briarproject/briar/android/util/RequestBluetoothDiscoverable.java

@@ -0,0 +1,31 @@
+package org.briarproject.briar.android.util;
+
+
+import android.content.Context;
+import android.content.Intent;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import androidx.activity.result.contract.ActivityResultContract;
+import androidx.annotation.Nullable;
+
+import static android.app.Activity.RESULT_CANCELED;
+import static android.bluetooth.BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE;
+import static android.bluetooth.BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION;
+
+@NotNullByDefault
+public class RequestBluetoothDiscoverable
+		extends ActivityResultContract<Integer, Boolean> {
+
+	@Override
+	public Intent createIntent(Context context, Integer duration) {
+		Intent i = new Intent(ACTION_REQUEST_DISCOVERABLE);
+		i.putExtra(EXTRA_DISCOVERABLE_DURATION, duration);
+		return i;
+	}
+
+	@Override
+	public Boolean parseResult(int resultCode, @Nullable Intent intent) {
+		return resultCode != RESULT_CANCELED;
+	}
+}

briar-android/src/main/res/layout/activity_fragment_container_toolbar.xml

@@ -4,7 +4,7 @@
 	android:layout_width="match_parent"
 	android:layout_height="match_parent"
 	android:orientation="vertical"
-	tools:context=".android.contact.add.nearby.KeyAgreementActivity">
+	tools:context=".android.contact.add.nearby.AddNearbyContactActivity">
 
 	<include layout="@layout/toolbar" />