显示我的位置

// Copyright 2025 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import 'dart:async';

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

/// User's location is shown as a blue dot and the My Location button
/// is displayed in the bottom right corner of the map. When the user taps
/// the button, the map pans to the user's current location.
class MyLocationSample extends StatefulWidget {
  const MyLocationSample({super.key});

  @override
  State<MyLocationSample> createState() => _MyLocationSampleState();
}

class _MyLocationSampleState extends State<MyLocationSample> {
  /// To use My Location on some platforms (such as Android),
  /// you need to ask the user for permission at runtime. See below.
  bool? _permissionGranted;

  @override
  Widget build(BuildContext context) {
    return GoogleMap(
      initialCameraPosition: CameraPosition(target: LatLng(37.78, -122.42)),

      // Enables the My Location layer.
      //
      // This feature is not available on all platforms and you MUST have
      // the appropriate location permission enabled in order for this to work.
      // See documentation of [GoogleMap.myLocationEnabled] for details.
      myLocationEnabled: _permissionGranted ?? false,

      // You can choose whether to show the button that lets the user
      // transport the camera to their current location.
      // This has no effect when `myLocationEnabled` is false.
      myLocationButtonEnabled: true,
    );
  }

  @override
  void initState() {
    super.initState();
    _requestPermission();
  }

  /// A *fake* implementation of requesting the permission.
  ///
  /// Real apps will use 3rd party packages such as `package:permission_handler`
  /// or build their own bespoke solution.
  Future<void> _requestPermission() async {
    // Wait a bit before continuing. This is required here because we call this
    // function from initState(), and that's too soon to be showing dialogues.
    await Future<void>.delayed(const Duration(seconds: 1));
    if (!mounted) return;

    var result = await showDialog<bool>(
      context: context,
      builder: (context) => SimpleDialog(
        title: Text('Requesting permission'),
        children: [
          SimpleDialogOption(
            onPressed: () => Navigator.pop(context, true),
            child: Text('Grant'),
          ),
          SimpleDialogOption(
            onPressed: () => Navigator.pop(context, false),
            child: Text('Deny'),
          ),
        ],
      ),
    );

    if (!mounted) return;
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(
        content: Text(
          'Fake permission granted: $result. '
          'Remember that for My Location to actually work, '
          'you need an actual runtime permission on some platforms. '
          'See the code of this sample for more info.',
        ),
        duration: const Duration(seconds: 10),
        showCloseIcon: true,
      ),
    );

    setState(() {
      _permissionGranted = result;
    });
  }
}
my_location.dart