packages/location_background/example/lib/background.dart

// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file

import 'dart:isolate';
import 'dart:ui';
import 'package:location_background_plugin/location_background_plugin.dart';

const String kLocationPluginPortName = 'location_plugin_port';

/// This is an example of a callback for LocationBackgroundPlugin's
/// `startMonitoringLocation`. A callback can be defined anywhere in an
/// application's code, but cannot be from another program.
class LocationMonitor {
  static void locationCallback(Location location) {
    print('Background Location: $location');
    // We use isolate ports to communicate between the main isolate and spawned
    // isolates since they do not share memory. The port lookup will return
    // null if the UI isolate has explicitly removed the mapping on shutdown.
    final SendPort uiSendPort =
        IsolateNameServer.lookupPortByName(kLocationPluginPortName);
    uiSendPort?.send(location.toJson());
  }
}