问题描述
我正在使用react-google-maps来显示用户的位置,该位置是使用ReactJS提取用户的坐标后得出的。但是,当我从原始位置移动标记时,初始标记停留在那里,因此创建了两个标记。我不知道该如何解决。
无论发生什么事情,我都希望地图标记保持在中心,而且当用户拖动或放大/缩小标记时,标记也将保持在中心,以便用户的位置始终位于地图的中心。这样,用户将能够更新她的位置。以您的示例为例,当我拖动鼠标时,标记保持固定在该位置。该组件的设计目的是使用户可以设置她的位置,并稍稍调整标记的位置,以防标记略有偏离 任何帮助将不胜感激:
App.js
import React from "react";
import WrappedMap from "./Map";
import "./styles.css";
export default class App extends React.Component {
constructor(props) {
super(props);
this.state = {
location: "",place: ""
};
}
handleLocation = (location) => {
this.setState({ location: location });
};
handlePlace = (place) => {
this.setState({ place: place });
};
render() {
return (
<div className="App">
<WrappedMap
googleMapURL={`https://maps.googleapis.com/maps/api/js?key=`}
loadingElement={<div style={{ height: `100%` }} />}
containerElement={
<div
style={{
height: `50%`,width: "95%",position: "absolute",marginTop: "25%"
}}
/>
}
mapElement={<div style={{ height: `100%` }} />}
location={this.state.location}
handleLocation={this.handleLocation}
changeState={this.changeState}
place={this.state.place}
handlePlace={this.handlePlace}
handleUseGPS={this.handleUseGPS}
/>
</div>
);
}
}
Map.js
import React,{ useRef,useState,useEffect } from "react";
import Geocode from "react-geocode";
import Button from "@material-ui/core/Button";
import {
GoogleMap,withScriptjs,withGoogleMap,Marker
} from "react-google-maps";
// import "./Sign.css";
function Map({
location,handleLocation,changeState,place,handlePlace,handleUseGPS
}) {
const [center,setCenter] = useState(location);
const [showMap,setShowMap] = useState(false);
const refMap = useRef(null);
var options = {
enableHighAccuracy: true,timeout: 10000,maximumAge: 30000
};
function success(pos) {
var crd = pos.coords;
console.log(crd);
console.log("Your current position is:");
console.log(`Latitude : ${crd.latitude}`);
console.log(`Longitude: ${crd.longitude}`);
console.log(`More or less ${crd.accuracy} meters.`);
const loc = {
lat: crd.latitude,lng: crd.longitude
};
handleLocation(loc);
getAndChangeAddress(loc);
setCenter(loc);
setShowMap(true);
}
function error(err) {
if (!navigator.geolocation) {
console.log("Geolocation is not supported by your browser");
} else {
console.log("loading");
}
let typeErr = err.code;
console.log(`Code: ${typeErr}`);
switch (typeErr) {
case 1:
console.log("User has not given permissions");
break;
case 2:
console.log(
"The acquisition of the geolocation Failed because at least one internal source of position returned an internal error."
);
break;
case 3:
console.log("Timeout reached before obtaining information");
break;
default:
break;
}
console.warn(`ERROR(${err.code}): ${err.message}`);
handlePlace("");
handleLocation({});
// handleUseGPS(true);
// changeState(7);
}
const handleBoundsChanged = () => {
const mapCenter = refMap.current.getCenter(); //get map center
setCenter(mapCenter);
};
useEffect(() => {
navigator.geolocation.getCurrentPosition(success,error,options);
},[]);
const handleDragEnd = () => {
const newCenter = refMap.current.getCenter();
const newLocation = {
lat: newCenter.lat(),lng: newCenter.lng()
};
handleLocation(newLocation);
getAndChangeAddress(newLocation);
};
const returnToMenu = () => {
// changeState(4);
};
const getAndChangeAddress = (loc) => {
const lat = loc.lat.toString();
const lng = loc.lng.toString();
console.log(typeof lat);
console.log(`From getAddress() function => lat: ${lat},lng: ${lng}`);
Geocode.fromLatLng(lat,lng).then(
(response) => {
const address = response.results[0].formatted_address;
console.log(`Formatted address: ${address}`);
handlePlace(address);
},(error) => {
console.error(error);
console.log("Error occuredd in getting address");
}
);
};
return (
<>
<div className="sign-in-form">
{showMap && (
<GoogleMap
ref={refMap}
defaultZoom={15}
defaultCenter={center}
onBoundsChanged={handleBoundsChanged}
onDragEnd={handleDragEnd}
>
<Marker
// defaultPlace={center}
position={center}
// ref={refMap}
// defaultPosition={center}
// onDrag={handleBoundsChanged}
// onDragEnd={handleDragEnd}
/>
</GoogleMap>
)}
{location.lat !== "" && (
<>
<hr />
<div style={{ margin: "1em" }}>{place}</div>
<hr />
</>
)}
<Button
className="otp-button"
onClick={returnToMenu}
fullWidth
variant="contained"
>
SAVE LOCATION
</Button>
</div>
</>
);
}
export default withScriptjs(withGoogleMap(Map));
另请参见:CodeSandbox Link
解决方法
我相信这里发生的事情是您将标记位置设置为center
,因此每当拖动时,都会生成另一个标记。
相反,react-google-maps docs显示了一个选项,您可以在其中将纬度和经度硬编码到标记上。好处:没有重复的标记。缺点:如果用户输入的其他地址需要标记移动,则需要编写更新功能。
更改这些行,您的问题应得到解决:
初始化钩子
function Map({
location,handleLocation,changeState,place,handlePlace,handleUseGPS
}) {
const [center,setCenter] = useState(location);
const [showMap,setShowMap] = useState(false);
const [mylat,setLat] = useState(0); {/* <------ add this hook */}
const [mylong,setLong] = useState(0); {/* <------ and this hook */}
const refMap = useRef(null);
...
功能成功()
function success(pos) {
var crd = pos.coords;
console.log(crd);
console.log("Your current position is:");
console.log(`Latitude : ${crd.latitude}`);
console.log(`Longitude: ${crd.longitude}`);
console.log(`More or less ${crd.accuracy} meters.`);
setLat(crd.latitude); {/* <------ set state here*/}
setLong(crd.longitude); {/* <------ set state here*/}
const loc = {
lat: crd.latitude,lng: crd.longitude
};
handleLocation(loc);
getAndChangeAddress(loc);
setCenter(loc);
setShowMap(true);
}
返回Google地图
<GoogleMap
ref={refMap}
defaultZoom={15}
defaultCenter={center}
onBoundsChanged={handleBoundsChanged}
onDragEnd={handleDragEnd}
>
<Marker
// defaultPlace={center}
position={{ lat: mylat,lng: mylong}} {/* <----- lat and long here */}
// ref={refMap}
// defaultPosition={center}
// onDrag={handleBoundsChanged}
// onDragEnd={handleDragEnd}
/>
</GoogleMap>
OP做出了澄清,要求<Marker />
实际上应该在屏幕中央移动,问题是存在重复项。
经过大量调试,我发现错误是由于呈现元素的方式引起的。更改:
index.js
import React,{ Component } from 'react';
import { render } from 'react-dom';
import App from "./App";
render(<App />,document.getElementById('root'));
您的问题已解决。这也可以:
import React from "react";
import ReactDOM from "react-dom";
import App from "./App";
const rootElement = document.getElementById("root");
ReactDOM.render(
<App />,{/* <-------- remove <StrictMode /> */}
rootElement
);
控制台中出现有关严格模式的警告,将其关闭似乎可以解决您的问题,这是GoogleMap
组件未按预期工作的原因的根源:
警告:已在严格模式树中检测到传统上下文API。 所有16.x版本都将支持旧的API,但是使用旧API的应用程序应迁移到新版本。 请更新以下组件:GoogleMap,标记 在此处了解有关此警告的更多信息:... 在StrictMode中(位于src / index.js:8)
我还发现了另一个StackOverflow问题,您的代码是根据该问题建模的,因此我也将在此处链接以供将来的查看者使用: