Leaflet geofence on multiple circles … detecting marker inside / outside

问题

I have some code that detects when the market is dragged inside and outside of a circle.

This works great but I was just wondering how I can have one market and multiple circles detected instead of just one.

Here is the current code:

var mymap = L.map('mapid', {
    center: [50.895763, -1.150556],
    zoom: 16
});

L.tileLayer('https://api.tiles.mapbox.com/v4/{id}/{z}/{x}/{y}.png?access_token=pk.eyJ1Ijoic3RldmVuc2F0Y2giLCJhIjoiY2p5eDR6MWgzMHRvbjNocnJkN2d2MjRwaSJ9.wd0OtBUQQfUtNxdduQA3lg', {
        maxZoom: 18,
        attribution: 'Map data &copy; <a href="https://www.openstreetmap.org/">OpenStreetMap</a> contributors, ' +
            '<a href="https://creativecommons.org/licenses/by-sa/2.0/">CC-BY-SA</a>, ' +
            'Imagery © <a href="https://www.mapbox.com/">Mapbox</a>',
        id: 'mapbox.streets'
    }).addTo(mymap);

var marker = new L.marker([50.896422, -1.148444],{
    draggable: true,
    autoPan: true
}).addTo(mymap);

var circle = L.circle([50.895763, -1.150556], {
    color: 'red',
    fillColor: '#f03',
    fillOpacity: 0.5,
    radius: 100
}).addTo(mymap);

marker.on('drag', function(e) {
    var d = mymap.distance(e.latlng, circle.getLatLng());
    var isInside = d < circle.getRadius();
    circle.setStyle({
        fillColor: isInside ? 'green' : '#f03'
    })
});

But I would like to add multiple circles instead of just one.

How can I do this?

回答1:

Put the circles in an array and forEach() over them with the radius test - something like this (substitute your own method of setting up the circles)

var mymap = L.map("mapid", {
  center: [50.895763, -1.150556],
  zoom: 16
});

L.tileLayer(
  "https://api.tiles.mapbox.com/v4/{id}/{z}/{x}/{y}.png?access_token=pk.eyJ1Ijoic3RldmVuc2F0Y2giLCJhIjoiY2p5eDR6MWgzMHRvbjNocnJkN2d2MjRwaSJ9.wd0OtBUQQfUtNxdduQA3lg",
  {
    maxZoom: 18,
    attribution:
      'Map data &copy; <a href="https://www.openstreetmap.org/">OpenStreetMap</a> contributors, ' +
      '<a href="https://creativecommons.org/licenses/by-sa/2.0/">CC-BY-SA</a>, ' +
      'Imagery © <a href="https://www.mapbox.com/">Mapbox</a>',
    id: "mapbox.streets"
  }
).addTo(mymap);

var marker = new L.marker([50.896422, -1.148444], {
  draggable: true,
  autoPan: true
}).addTo(mymap);

var circles = [];

circles[0] = L.circle([50.895763, -1.150556], {
  color: "red",
  fillColor: "#f03",
  fillOpacity: 0.5,
  radius: 100
}).addTo(mymap);

circles[1] = L.circle([some - other - coordinates], {
  color: "red",
  fillColor: "#f03",
  fillOpacity: 0.5,
  radius: 100
}).addTo(mymap);

marker.on("drag", function(e) {
  circles.forEach(function(circle) {
    var d = mymap.distance(e.latlng, circle.getLatLng());
    var isInside = d < circle.getRadius();
    circle.setStyle({
      fillColor: isInside ? "green" : "#f03"
    });
  });
});

来源：https://stackoverflow.com/questions/57400995/leaflet-geofence-on-multiple-circles-detecting-marker-inside-outside

标签

geolocation

leaflet

maps

geofencing