ngx-leaflet：如何添加自定义控件？

Question

我已经尝试使用ngx-leaflet来实现此leaflet tutorial了一段时间。

在跟随本教程的同时，关于如何实现自定义控件或图例绝对没有明确的documentation。

var info = L.control();

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

// method that we will use to update the control based on feature properties passed
info.update = function (props) {
    this._div.innerHTML = '<h4>US Population Density</h4>' +  (props ?
        '<b>' + props.name + '</b><br />' + props.density + ' people / mi<sup>2</sup>'
        : 'Hover over a state');
};

info.addTo(map);

创建图例也是如此。

有人可以指出正确的方向，尝试使用ngx-leaflet lib在Angular 7中实现此功能吗？

import { control, featureGroup, geoJson, icon, latLng, LatLngExpression, Map, Marker, marker, popup, tileLayer } from 'leaflet';

  onMapReady(map: Map) {
    this.map = map;

    // create info control
    let info = control(
      {
        onAdd: map => {

        }
      }
    )
    info.addTo(map);

我知道您需要执行类似this的操作，但是我不想添加圆​​形或形状，而是要添加上面屏幕截图中的自定义控件以及图例。

Answer 1

使此示例工作唯一需要做的就是监听onMapReady事件并将该教程的所有代码放在其中。地图参考就是您想要的，它是该函数的参数。

特别是：

<div
  style="height: 100vh"
  leaflet
  [leafletOptions]="options"
  (leafletMapReady)="onMapReady($event)"
></div>

ts：

onMapReady(map) {
 // place all the tutorial code inside here
 ...

// control that shows state info on hover
let info = L.control();

// here you want the reference to be info, therefore this = info
// so do not use es6 to access the the class instance
info.onAdd = function (map) {
  this._div = L.DomUtil.create('div', 'info');
  this.update();
  return this._div;
};

// also here you want the reference to be info, therefore this = info
// so do not use es6 to access the class instance
info.update = function (props) {
  this._div.innerHTML = '<h4>US Population Density</h4>' + (props ?
    '<b>' + props.name + '</b><br />' + props.density + ' people / mi<sup>2</sup>'
    : 'Hover over a state');
};

info.addTo(map);
...
const legend = L.control({ position: 'bottomright' });

legend.onAdd = map => {

  let div = L.DomUtil.create('div', 'info legend'),
    grades = [0, 10, 20, 50, 100, 200, 500, 1000],
    labels = [],
    from, to;

  for (var 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);
}

使用ngx-leaflet在demo中查看Angular 7中的完整示例