javascript - React leaflet map 库中的GeoJSON样式

Question

我已经在我的react项目中实现了传单 map 库https://react-leaflet.js.org/en/并实现了如下所示的 geojson map 组件

class MapContainer extends React.Component {
  state = {
    greenIcon: {
      lat: 8.3114,
      lng: 80.4037
    },
    zoom: 8
  };

  grenIcon = L.icon({
    iconUrl: leafGreen,
    iconSize: [24, 24], // size of the icon
    //iconAnchor: [22, 94], // point of the icon which will correspond to marker's location
    popupAnchor: [-3, -16]
  });

  render() {

    const positionGreenIcon = [
      this.state.greenIcon.lat,
      this.state.greenIcon.lng
    ];

    return (
      <div className="mapdata-container">
        <Map className="map" style={{height:'100%',width:'100%'}} center={positionGreenIcon} zoom={this.state.zoom}>
          <GeoJSON data={geo}/>
          <Marker position={positionGreenIcon} icon={this.grenIcon}>
            <Popup>I am a green leaf</Popup>
          </Marker>
        </Map>
      </div>
    );
  }
}

export default MapContainer;

看起来像这样

我想用不同的颜色为每个省份着色，但文档中没有太多关于如何执行此操作的信息。

这是我使用的 geojson 文件。 https://raw.githubusercontent.com/thejeshgn/srilanka/master/electoral_districts_map/LKA_electrol_districts.geojson

如何用不同的颜色填充每个省份。

Answer 1

您可以在 GeoJSON 包装器上使用 style 属性轻松实现这一点。创建一个接受该功能作为参数的样式方法。然后在 fillColor 属性中使用属性:{ electoralDistrict } 来标识选区并返回所需的颜色:以下是一个示例:

class MapContainer extends React.Component {
  state = {
    greenIcon: {
      lat: 8.3114,
      lng: 80.4037
    },
    zoom: 8
  };

  grenIcon = L.icon({
    iconSize: [24, 24], // size of the icon
    //iconAnchor: [22, 94], // point of the icon which will correspond to marker's location
    popupAnchor: [-3, -16],
    iconUrl: leafGreen
  });

  giveColor = district => {
    switch (district) {
      case "Matara":
        return "red";
      case "Polonnaruwa":
        return "brown";
      case "Ampara":
        return "purple";
      default:
        return "white";
    }
  };

  style = feature => {
    const {
      properties: { electoralDistrict }
    } = feature;
    return {
      fillColor: this.giveColor(electoralDistrict),
      weight: 0.3,
      opacity: 1,
      color: "purple",
      dashArray: "3",
      fillOpacity: 0.5
    };
  };

  render() {
    const positionGreenIcon = [
      this.state.greenIcon.lat,
      this.state.greenIcon.lng
    ];

    return (
      <div className='mapdata-container'>
        <Map
          className='map'
          style={{ height: "100vh", width: "100%" }}
          center={positionGreenIcon}
          zoom={this.state.zoom}
        >
          <GeoJSON data={geo} style={this.style} />
          <Marker position={positionGreenIcon} icon={this.grenIcon}>
            <Popup>I am a green leaf</Popup>
          </Marker>
        </Map>
      </div>
    );
  }
}