反应传单地图中心没有改变

问题描述

我正在设置地图以查找某个人的坐标，然后将该位置放在地图上。但出于某种原因，坐标未显示在地图上。我 console.log 以确保状态变量（存储坐标的位置）发出正确的坐标，并且它们是。我不知道为什么地图不会改变它们。

我的代码：

import { StatusBar } from "expo-status-bar";
import React from "react";
import { StyleSheet,Text,View } from "react-native";
import { MapContainer,TileLayer,Marker,Popup } from "react-leaflet";
import Constants from "expo-constants";
import * as Location from "expo-location";
import * as Permissions from "expo-permissions";
import { render } from "react-dom";

import "leaflet/dist/leaflet.css";

export default class App extends React.Component {
  constructor() {
    super();
    this.state = {
      ready: false,where: { lat: '',lng: '' },error: null,};
  }

  componentDidMount() {
    let geoOptions = {
      enableHighAccuracy: true,timeOut: 20000,maximumAge: 60 * 60 * 24,};
    this.setState({ ready: false,error: null });
    navigator.geolocation.getCurrentPosition(
      this.geoSuccess,this.geoFailure,geoOptions
    );
  }
  geoSuccess = (position) => {
    console.log(position.coords.latitude);
    console.log(position.coords.longitude);
    console.log(this.state.where?.lng);
    console.log(this.state.where?.lat);
    

    this.setState({
      ready: true,where: { lat: position.coords.latitude,lng: position.coords.longitude 
      },});
    console.log(this.state.where?.lng);
    console.log(this.state.where?.lat);
  };
  geoFailure = (err) => {
    this.setState({ error: err.message });
    console.log(this.state.error);
  };

  
  
  render() {
    const position = [this.state.where?.lat,this.state.where?.lng];
    return (
      <>
        {(this.state.where != null || this.state.where != undefined) && 
          <MapContainer
            style={{ height: "100%",width: "100%" }}
            center={position}
            zoom="30"
            scrollWheelZoom={true}
            
          >
            <TileLayer
              attribution='&copy; <a href="http://osm.org/copyright">OpenStreetMap</a> contributors'
              url="https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png"
            />
          </MapContainer>
        }
      </>
    );
  }
}

解决方法

来自官方文档

除了它的孩子，MapContainer 道具是不可变的：改变 第一次设置后，它们将不会影响 地图实例或其容器。

使用将在位置更改时更改地图视图的子组件

function ChangeMapView({ coords }) {
  const map = useMap();
  map.setView(coords,map.getZoom());

  return null;
}

像这样使用它：

 <MapContainer
     style={{ height: "100vh",width: "100%" }}
     center={position}
     zoom="30"
     scrollWheelZoom={true}
     >
     <TileLayer
          attribution='&copy; <a href="http://osm.org/copyright">OpenStreetMap</a> contributors'
         url="https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png"
     />
     <ChangeMapView coords={position} />
</MapContainer>

Demo