Request user to turn on location for adding contact nearby on API 28+

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

@@ -1,6 +1,8 @@
 package org.briarproject.briar.android.contact.add.nearby;
 
 import android.content.Context;
+import android.content.Intent;
+import android.location.LocationManager;
 
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.BaseActivity;
@@ -15,6 +17,7 @@ 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 android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS;
 import static androidx.core.app.ActivityCompat.shouldShowRequestPermissionRationale;
 import static androidx.core.content.ContextCompat.checkSelfPermission;
 import static org.briarproject.briar.android.util.UiUtils.getGoToSettingsListener;
@@ -45,6 +48,19 @@ class AddNearbyContactPermissionManager {
 		locationPermission = Permission.UNKNOWN;
 	}
 
+	/**
+	 * @return true if location is enabled,
+	 * or it isn't required due to this being a SDK < 28 device.
+	 */
+	static boolean isLocationEnabled(Context ctx) {
+		if (SDK_INT >= 28) {
+			LocationManager lm = ctx.getSystemService(LocationManager.class);
+			return lm.isLocationEnabled();
+		} else {
+			return true;
+		}
+	}
+
 	static boolean areEssentialPermissionsGranted(Context ctx,
 			boolean isBluetoothSupported) {
 		int ok = PERMISSION_GRANTED;
@@ -61,7 +77,8 @@ class AddNearbyContactPermissionManager {
 	}
 
 	boolean checkPermissions() {
-		if (areEssentialPermissionsGranted()) return true;
+		boolean locationEnabled = isLocationEnabled(ctx);
+		if (locationEnabled && areEssentialPermissionsGranted()) return true;
 		// If an essential permission has been permanently denied, ask the
 		// user to change the setting
 		if (cameraPermission == Permission.PERMANENTLY_DENIED) {
@@ -86,8 +103,10 @@ class AddNearbyContactPermissionManager {
 		} else if (locationPermission == Permission.SHOW_RATIONALE) {
 			showRationale(R.string.permission_location_title,
 					R.string.permission_location_request_body);
-		} else {
+		} else if (isLocationEnabled(ctx)) {
 			requestPermissions();
+		} else {
+			showLocationDialog(ctx);
 		}
 		return false;
 	}
@@ -113,6 +132,20 @@ class AddNearbyContactPermissionManager {
 		builder.show();
 	}
 
+	private static void showLocationDialog(Context ctx) {
+		AlertDialog.Builder builder =
+				new AlertDialog.Builder(ctx, R.style.BriarDialogTheme);
+		builder.setTitle(R.string.permission_location_setting_title);
+		builder.setMessage(R.string.permission_location_setting_body);
+		builder.setNegativeButton(R.string.cancel, null);
+		builder.setPositiveButton(R.string.permission_location_setting_button,
+				(dialog, which) -> {
+					Intent i = new Intent(ACTION_LOCATION_SOURCE_SETTINGS);
+					ctx.startActivity(i);
+				});
+		builder.show();
+	}
+
 	private void requestPermissions() {
 		String[] permissions;
 		if (isBluetoothSupported) {

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

@@ -83,6 +83,7 @@ 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.AddNearbyContactPermissionManager.isLocationEnabled;
 import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactViewModel.BluetoothDecision.REFUSED;
 import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactViewModel.BluetoothDecision.UNKNOWN;
 
@@ -365,7 +366,9 @@ class AddNearbyContactViewModel extends AndroidViewModel
 	void showQrCodeFragmentIfAllowed() {
 		boolean permissionsGranted = areEssentialPermissionsGranted(
 				getApplication(), isBluetoothSupported());
-		if (isActivityResumed && wasContinueClicked && permissionsGranted) {
+		boolean locationEnabled = isLocationEnabled(getApplication());
+		if (isActivityResumed && wasContinueClicked && permissionsGranted &&
+				locationEnabled) {
 			if (isWifiReady() && isBluetoothReady()) {
 				LOG.info("Wifi and Bluetooth are ready");
 				startAddingContact();

briar-android/src/main/res/values/strings.xml

@@ -609,6 +609,9 @@
 	<string name="permission_camera_location_request_body">To scan the QR code, Briar needs access to the camera.\n\nTo discover Bluetooth devices, Briar needs permission to access your location.\n\nBriar does not store your location or share it with anyone.</string>
 	<string name="permission_camera_denied_body">You have denied access to the camera, but adding contacts requires using the camera.\n\nPlease consider granting access.</string>
 	<string name="permission_location_denied_body">You have denied access to your location, but Briar needs this permission to discover Bluetooth devices.\n\nPlease consider granting access.</string>
+	<string name="permission_location_setting_title">Location setting</string>
+	<string name="permission_location_setting_body">Your device\'s location setting must be turned on to find other devices via Bluetooth. Please enable location to continue. You can disable it again afterwards.</string>
+	<string name="permission_location_setting_button">Enable location</string>
 	<string name="qr_code">QR code</string>
 	<string name="show_qr_code_fullscreen">Show QR code fullscreen</string>