packages/google_maps_flutter/google_maps_flutter/example/lib/map_coordinates.dart

// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// ignore_for_file: public_member_api_docs

import 'package:flutter/material.dart';
import 'package:google_maps_flutter/google_maps_flutter.dart';
import 'page.dart';

const CameraPosition _kInitialPosition =
    CameraPosition(target: LatLng(-33.852, 151.211), zoom: 11.0);

class MapCoordinatesPage extends GoogleMapExampleAppPage {
  const MapCoordinatesPage({Key? key})
      : super(const Icon(Icons.map), 'Map coordinates', key: key);

  @override
  Widget build(BuildContext context) {
    return const _MapCoordinatesBody();
  }
}

class _MapCoordinatesBody extends StatefulWidget {
  const _MapCoordinatesBody();

  @override
  State<StatefulWidget> createState() => _MapCoordinatesBodyState();
}

class _MapCoordinatesBodyState extends State<_MapCoordinatesBody> {
  _MapCoordinatesBodyState();

  GoogleMapController? mapController;
  LatLngBounds _visibleRegion = LatLngBounds(
    southwest: const LatLng(0, 0),
    northeast: const LatLng(0, 0),
  );

  @override
  Widget build(BuildContext context) {
    final GoogleMap googleMap = GoogleMap(
      onMapCreated: onMapCreated,
      initialCameraPosition: _kInitialPosition,
    );

    final List<Widget> columnChildren = <Widget>[
      Padding(
        padding: const EdgeInsets.all(10.0),
        child: Center(
          child: SizedBox(
            width: 300.0,
            height: 200.0,
            child: googleMap,
          ),
        ),
      ),
    ];

    if (mapController != null) {
      final String currentVisibleRegion = 'VisibleRegion:'
          '\nnortheast: ${_visibleRegion.northeast},'
          '\nsouthwest: ${_visibleRegion.southwest}';
      columnChildren.add(Center(child: Text(currentVisibleRegion)));
      columnChildren.add(_getVisibleRegionButton());
    }

    return Column(
      mainAxisAlignment: MainAxisAlignment.start,
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: columnChildren,
    );
  }

  Future<void> onMapCreated(GoogleMapController controller) async {
    final LatLngBounds visibleRegion = await controller.getVisibleRegion();
    setState(() {
      mapController = controller;
      _visibleRegion = visibleRegion;
    });
  }

  Widget _getVisibleRegionButton() {
    return Padding(
      padding: const EdgeInsets.all(8.0),
      child: ElevatedButton(
        child: const Text('Get Visible Region Bounds'),
        onPressed: () async {
          final LatLngBounds visibleRegion =
              await mapController!.getVisibleRegion();
          setState(() {
            _visibleRegion = visibleRegion;
          });
        },
      ),
    );
  }
}