Flutter路线规划插件osrm的使用

概述

osrm 是一个用于Dart和Flutter的OSRM（Open Source Routing Machine）客户端。它提供了一个简单易用的接口，用于与OSRM服务器通信并获取路径规划和其他相关信息。

安装

在项目的 pubspec.yaml 文件中添加以下依赖项：

dependencies:
  osrm: ^latest_version

然后运行 flutter pub get 来安装依赖。

使用方法

首先需要创建一个 OSRM 类的实例，之后可以通过该实例调用不同的服务，如 nearest 和 route。

简单示例

Nearest Service

import 'package:osrm/osrm.dart';

void main() async {
  final osrm = Osrm();

  // 获取最近的3个点
  NearestResponse response = await osrm.nearest(
    NearestOptions(
      coordinate: (-0.1234, 51.1234),
      number: 3,
    ),
  );

  print(response);
}

路径规划服务（GoogleMap中的方向）

import 'package:osrm/osrm.dart';

void main() async {
  final osrm = Osrm();

  final route = await osrm.route(
    RouteRequest(
      coordinates: [
        (-0.1234, 51.1234), // 点A
        (-0.1234, 51.1234), // 点B
        (-0.1234, 51.1234), // 点C
      ],
      alternatives: OsrmAlternative.true_,
      steps: true,
      annotations: OsrmAnnotation.true_,
      overview: OsrmOverview.full,
      continueStraight: OsrmContinueStraight.true_,
      format: OsrmFormat.json,
      waypoints: [
        /// 访问顺序
        OsrmWaypoint(
          distance: 0.0,
          location: (-0.1234, 51.1234),
        ),
      ],
    ),
  );

  print(route);
}

更完整的Flutter示例

下面是一个更完整的Flutter应用示例，展示了如何在地图上显示路径规划结果。

import 'package:flutter/material.dart';
import 'package:flutter_map/flutter_map.dart';
import 'package:latlong2/latlong.dart';
import 'package:osrm/osrm.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'OSRM Flutter Example',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MapScreen(),
    );
  }
}

class MapScreen extends StatefulWidget {
  [@override](/user/override)
  _MapScreenState createState() => _MapScreenState();
}

class _MapScreenState extends State<MapScreen> {
  List<LatLng> _routePoints = [];

  [@override](/user/override)
  void initState() {
    super.initState();
    _fetchRoute();
  }

  Future<void> _fetchRoute() async {
    final osrm = Osrm();

    final route = await osrm.route(
      RouteRequest(
        coordinates: [
          (2.829099, 36.479960), // Point A
          (2.825987, 36.473662), // Point B
        ],
      ),
    );

    setState(() {
      _routePoints = route.routes.first.geometry.map((coord) => LatLng(coord[1], coord[0])).toList();
    });
  }

  [@override](/user/override)
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('OSRM Flutter Example'),
      ),
      body: FlutterMap(
        options: MapOptions(
          center: LatLng(36.479960, 2.829099),
          zoom: 13.0,
        ),
        layers: [
          TileLayerOptions(
            urlTemplate: "https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png",
            subdomains: ['a', 'b', 'c'],
          ),
          PolylineLayerOptions(
            polylines: [
              Polyline(
                points: _routePoints,
                strokeWidth: 4.0,
                color: Colors.blue,
              ),
            ],
          ),
        ],
      ),
    );
  }
}