在地图上定位

Question

我想在地图上添加模块 "React-leaflet-locate-control"。不幸的是，我遇到了这个错误 "TypeError: Cannot read property 'addLayer' of undefined"，我不知道如何纠正这个错误。

你能帮帮我吗？

这是我的组件地图：

import './Map.css';
import React, { Component } from 'react';
import { Map, TileLayer, Marker, Popup } from 'react-leaflet';
import L from "leaflet";
import { getLat, getLng } from '../../Store.js';
import SearchBar from '../SearchBar/SearchBar.js';
import LocateControl from 'react-leaflet-locate-control';

const customMarker = new L.icon({
    iconUrl: "https://unpkg.com/leaflet@1.4.0/dist/images/marker-icon.png",
    iconSize: [25, 41],
    iconAnchor: [13, 0]
});

export default class MapLeaflet extends Component {

    constructor(props) {
        super(props);
        this.state = {
            lat: getLat(),
            lng: getLng(),
        }
    }

    updateMarker = (e) => {
        this.props.updateMarkerPosition(e.latlng.lat, e.latlng.lng);
        this.setState({
            lat: e.latlng.lat,
            lng: e.latlng.lng
        })
    }

    render() {
        const position = [this.state.lat, this.state.lng]
        const locateOptions = {
            position: 'topright',
            strings: {
                title: 'Show me where I am, yo!'
            },
            onActivate: () => {} // callback before engine starts retrieving locations
        }
        return (
            <div className="map">
                <Map center={position} zoom={13} className="map" onClick={this.updateMarker}>
                    <TileLayer
                        attribution='&amp;copy <a href="http://osm.org/copyright">OpenStreetMap</a> contributors'
                        url="https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png"
                    />
                    <Marker position={position} icon={customMarker}>
                        <Popup>
                            A pretty CSS3 popup. <br /> Easily customizable.
                        </Popup>
                    </Marker>
                    <SearchBar />
                    <LocateControl options={locateOptions} startDirectly/>
                </Map>
            </div>
        )
    }
}

Answer 1

react-leaflet-locate-control package is not compatible with the latest version (v2) of react-leaflet and in fact the similar issue has been reported here

由于 react-leaflet-locate-control 表示 leaflet-locatecontrol plugin 的包装器，因此可以使用 react-leaflet 的以下自定义组件，它提供与 react-leaflet-locate-control 相同的功能：

import React, { Component } from "react";
import { withLeaflet } from "react-leaflet";
import Locate from "leaflet.locatecontrol";

class LocateControl extends Component {
  componentDidMount() {
    const { options, startDirectly } = this.props;
    const { map } = this.props.leaflet;

    const lc = new Locate(options);
    lc.addTo(map);

    if (startDirectly) {
      // request location update and set location
      lc.start();
    }
  }

  render() {
    return null;
  }
}

export default withLeaflet(LocateControl);

Installation

1) install a plugin: npm install leaflet.locatecontrol

2) include the following CSS resources into public/index.html:
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css">
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/leaflet.locatecontrol/dist/L.Control.Locate.min.css">

这里是a demo (source code)

Answer 2

如果你像我一样使用 Typescript。我使用下面的组件代码

使其与 v2 一起使用

import L from 'leaflet';
import { withLeaflet, MapControl, MapControlProps } from 'react-leaflet';
import Locate from 'leaflet.locatecontrol';
import './Geolocate.css';

type GeolocateProps = L.Control.LocateOptions & MapControlProps;

class Geolocate extends MapControl<GeolocateProps> {
  createLeafletElement(props: GeolocateProps) {
    const { leaflet, ...options } = props;
    const locate = Locate as any;
    const lc = new locate(options);
    return lc;
  }
}
export default withLeaflet(Geolocate);

此外，您可以跳过包含 Font awesome 和库自己的 css 文件，而是提供您自己的样式

Geolocate.css

.leaflet-control-locate a.leaflet-bar-part div {
  background-image: url(../../images/geolocation.png);
  background-size: 22px 74px;
  background-position: top 2px left 2px;
  background-repeat: no-repeat;
  width: 30px;
  height: 30px;
}

.leaflet-control-locate a.leaflet-bar-part div.loading {
  background-position: top -24px left 2px;
}

.leaflet-control-locate.active a.leaflet-bar-part div.locate {
  background-position: top -50px left 2px;
}

@media (-webkit-min-device-pixel-ratio: 2), (min-resolution: 192dpi) {
  .leaflet-control-locate a.leaflet-bar-part div {
    background-image: url(../../images/geolocation-2x.png);
  }
}

当然，您必须先使用 npm 安装 leaflet.locatecontrol

npm i leaflet.locatecontrol

希望对您有所帮助。

Answer 3

您实际上不需要任何外部模块来获取 React 或任何其他 JavaScript 库中的当前位置

你可以使用

if (navigator.geolocation) {
    navigator.geolocation.getCurrentPosition(position => //Do something with it  );
  }

这是一种反应方式：

 const [currentLocation, setCurrentLocation] = React.useState([0, 0]);
//change [0,0] to something that makes sense to your users in case they deny access to location.  


    useEffect(() => {
        if (navigator.geolocation) {
            navigator.geolocation.getCurrentPosition(
                position => 
                        setCurrentLocation([position.coords.latitude, position.coords.longitude]))
        }
    }, []);


    return (
        <Map center={currentLocation} zoom={15}>
          // the rest ie . TileLayer,Marker,Popup 
        </Map>

在地图上定位

React Locate on map

javascript

reactjs

react-leaflet