Question

我正在遇到问题，因为我正在使用Leaflet和React，问题是Leaflet也想控制DOM呈现，就我研究而言。

现在，各国将使用与后端信息（范围1 - > 100）对应的特定颜色代码正确着色。但是，它每分钟更新一次。更新后，国家/地区颜色不会更改。但是，如果你将鼠标悬停在给定的国家/地区上，这有点奇怪。

这是我的源代码：

import React from 'react';
import L from 'leaflet';
import countries from './countries.js';


var Worldmap = React.createClass({

    render: function() {

        if(!this.props.data)
            return <div> loading world map ..  </div>;

        let dataratio = this.props.data; // Props from main component
        let size = Object.keys(dataratio).length; // Do we have data?

        if(size > 1) { // If we do have data, ..

            let dataratioToArr = Object.keys(dataratio).map(data => [ data, dataratio[data]]); // Conv. map to multidimensional array

            let featuresArr = countries.features; // array of all countries in array features from countries.js

            for(let i = 0; i < featuresArr.length; i++) // i = 178(no. of countries)
                for(let j = 0; j < dataratioToArr.length; j++) // j = no. of countries we have with dataratio > 1 from backend
                    if(dataratioToArr[j][0] == featuresArr[i].id) // If ISO-3 compliant ID of country(f.e. "USA") matches, push a "data" property to countries.js
                        featuresArr[i].properties.data = dataratioToArr[j][1];
        }

        return(
            <div id="leafletmap" style={{width: "100%", height: "80%", border: "2px solid black" }} />
        )
    },

    componentDidMount : function() {
        let geolocation =  [];
        // Retrieve geoloc coordinates
        navigator.geolocation.getCurrentPosition(function(position) {
            let lat = position.coords.latitude;
            let lon = position.coords.longitude;

            if(lat != null && lon != null) // If we can get latitude and longitude, reset geolocation and push values.
                geolocation.length = 0;
            geolocation.push(lat, lon);
            if(!lat || !lon) // If we can't get latitude or longitude, set a default value.
                geolocation = [0,0];

            let map = L.map('leafletmap').setView(geolocation, 3); // ([coordinates], zoomlevel)

            let info = L.control();

            info.onAdd = function (map) {
                this._div = L.DomUtil.create('div', 'info');
                this.update();
                return this._div;
            };

            info.update = function (props) {
                this._div.innerHTML = '<h4>Data ratio</h4>' +  (props ?
                    '<b>' + props.name + '</b><br />' + props.data + ' ratio'
                        : 'Hover over a country');
            };

            info.addTo(map);


            function getColor(d) {
                return d > 90 ? '#4a1486' :
                    d > 75  ? '#6a51a3' :
                        d > 50  ? '#807dba' :
                            d > 25  ? '#9e9ac8' :
                                d > 15   ? '#bcbddc' :
                                    d > 5   ? '#dadaeb' :
                                        d > 1   ? '#f2f0f7' :
                                            '#D3D3D3'; // Default color of data doesn't exist or is 0.
            }


            function style(feature) {
                return {
                    weight: 2,
                    opacity: 1,
                    color: 'white',
                    fillOpacity: 1,
                    fillColor: getColor(feature.properties.data)
                };
            }

            function highlightFeature(e) {
                let layer = e.target;

                layer.setStyle({
                    weight: 5,
                    color: '#666',
                    fillOpacity: 0.7
                });

                if (!L.Browser.ie && !L.Browser.opera && !L.Browser.edge) {
                    layer.bringToFront();
                }

                info.update(layer.feature.properties);
            }

            let geojson;

            function resetHighlight(e) {
                geojson.resetStyle(e.target);
                info.update();
            }

            function zoomToFeature(e) {
                map.fitBounds(e.target.getBounds());
            }

            function onEachFeature(feature, layer) {
                layer.on({
                    mouseover: highlightFeature,
                    mouseout: resetHighlight,
                    click: zoomToFeature
                });
            }


            geojson = L.geoJson(countries, { // from import
                style: style,
                onEachFeature: onEachFeature
            }).addTo(map);

            let legend = L.control({position: 'bottomright'});

            legend.onAdd = function (map) {

                let div = L.DomUtil.create('div', 'info legend'),
                    grades = [1, 5, 15, 25, 50, 75, 90],
                    labels = [],
                    from, to;

                for (let i = 0; i < grades.length; i++) {
                    from = grades[i];
                    to = grades[i + 1];

                    labels.push(
                        '<i style="background:' + getColor(from + 1) + '"></i> ' +
                        from + (to ? '&ndash;' + to : '+'));
                }

                div.innerHTML = labels.join('<br>');
                return div;
            };

            legend.addTo(map);
        });

    }
});

export default Worldmap

如何在收到新的this.props.data后强制传单重绘或刷新地图？

我尝试使用componentDidUpdate我基本上会做map.remove()，但后来我遇到了不同组件之间的范围问题..它全部加载在componentDidMount中，如果你调用传单再次映射它会说它已经初始化了。

Answer 1

扩展我的评论。您需要清除图层并重新向地图添加数据。在您的情况下，您可能需要更改访问地图和geojson处理的方式，但我在这里给出了一般解决方案。

   componentDidMount(){
      var map = this.map = L.map('leafletmap');
   } 


   componentWillReceiveProps(nextProps) {
      if (nextProps.data !== this.props.data) {
       this.map.clearLayers();
      }
   } 


  componentDidUpdate(prevProps,prevState) {
      if (prevProps.data !== this.props.data) {
          this.map.addData(geojsonData);
       }
   }

如何强制传单更新地图？

1 个答案: