Check if coordinate exists in any of multiple circles in Google Maps

Question

I have a Google Map that has multiple circles around multiple points which I've drawn the following way:

for (i = 0; i < markers.length; i++) {
    var circle = new google.maps.Circle({
        map: map,
        radius: parseInt(radius_entry[markers[i][0]]),
        fillColor: '#2c3e50',
        strokeColor: '#2c3e50',
        strokeOpacity: 0
    });

    var position = new google.maps.LatLng(markers[i][1], markers[i][2]);
    pinIcon = new google.maps.MarkerImage(
        "assets/images/station_maker.png",
        null, /* size is determined at runtime */
        null, /* origin is 0,0 */
        null, /* anchor is bottom center of the scaled image */
        new google.maps.Size(21, 34)
    );
    marker = new google.maps.Marker({
        position: position,
        map: map,
        title: markers[i][0],
    });
    marker.setIcon(pinIcon)
    circle.bindTo('center', marker, 'position');
    google.maps.event.addListener(circle, 'click', function(ev) { //Placing marker only on clicks inside a circle
        placeMarker(ev.latLng);
    });
    bounds.extend(position);
    map.fitBounds(bounds);
}

I have also provided a method for users to search for a location using the places library on the same map which is a very straightforward implementation.

var input = document.getElementById('search-places');
var searchBox = new google.maps.places.SearchBox(input);
google.maps.event.addListener(searchBox, 'places_changed', function() {
    var places = searchBox.getPlaces();
    if (places.length == 0) {
        return;
    }
    var bounds = new google.maps.LatLngBounds();
    for (var i = 0, place; place = places[i]; i++) {
        bounds.extend(place.geometry.location);
    }
    map.fitBounds(bounds);
});

However, I want to add a mechanism that checks if the searched place falls within any of the circles drawn earlier. I found this method:

polygon.containsLocation()

https://developers.google.com/maps/documentation/javascript/examples/poly-containsLocation

But this didn't work for circles.

I also found this SO question How to detect if a point is in a Circle? but it deals with only one circle drawn on a map. How do I achieve this scenario?

Why do you think you can't use the same approach as [that question](http://stackoverflow.com/questions/14598426/how-to-detect-if-a-point-is-in-a-circle) for multiple circles? You will have to keep references to all your circles. — geocodezip, Sep 22 '15 at 22:57
FYI - MarkerImage was deprecated after v=3.10 (a long time ago...) — geocodezip, Sep 22 '15 at 22:59
@geocodezip Sorry. `placemMarker` is a separate function that I didn't add. I kept references to the circles. My question is, how do I pass the `point` variable ? I get a `places.geometry.location` object on place change? — Newtt, Sep 23 '15 at 07:28

score 3 · Accepted Answer · answered Sep 23 '15 at 12:08

You could utilize the following function to determine whether point is located inside a circle:

function circleContainsLocation(point, circle)
{
    var radius = circle.getRadius();
    var center = circle.getCenter();
    return (google.maps.geometry.spherical.computeDistanceBetween(point, center) <= radius)
}

Then to introduce circles array to store all rendered circles.

And then add the following code to determine whether place is located in circles or not:

for (var i = 0, place; place = places[i]; i++) {

     var result = circles.filter(function(c){
         if(circleContainsLocation(place.geometry.location,c))
               return c;
     });
     var placeFound = (result.length > 0);
     if(placeFound){
            console.log('Place is found');
     }

}

Complete example

var circles = [];
function initMap() {

    var map = new google.maps.Map(document.getElementById('map'), {
        center: { lat: -33.8688, lng: 151.2195 },
        zoom: 13,
        mapTypeId: google.maps.MapTypeId.ROADMAP
    });


    var input = document.getElementById('pac-input');
    var searchBox = new google.maps.places.SearchBox(input);
    map.controls[google.maps.ControlPosition.TOP_LEFT].push(input);


    var markers = [
      ['Sydney',-33.867080, 151.209450,50000],
      ['Newcastle NSW',-32.927896, 151.768989,10000]
    ];

    var bounds = new google.maps.LatLngBounds();
    for (var i = 0; i < markers.length; i++) {
        var circle = new google.maps.Circle({
            map: map,
            radius: markers[i][3],
            fillColor: '#2c3e50',
            strokeColor: '#2c3e50',
            strokeOpacity: 0
        });
        circles.push(circle);

        var position = new google.maps.LatLng(markers[i][1], markers[i][2]);
        var marker = new google.maps.Marker({
            position: position,
            map: map,
            title: markers[i][0],
        });   
        circle.bindTo('center', marker, 'position');             
        bounds.extend(position);
    }
    map.fitBounds(bounds);


    google.maps.event.addListener(searchBox, 'places_changed', function () {
        var places = searchBox.getPlaces();
        if (places.length == 0) {
            return;
        }
        var bounds = new google.maps.LatLngBounds();
        for (var i = 0, place; place = places[i]; i++) {

            var result = circles.filter(function(c){
                if(circleContainsLocation(place.geometry.location,c))
                   return c;
            })
            var placeFound = (result.length > 0);
            if(placeFound){
                document.getElementById('output').innerHTML = 'Place is found';
            }

            bounds.extend(place.geometry.location);
        }
        map.fitBounds(bounds);
    });

}



function circleContainsLocation(point, circle)
{
    var radius = circle.getRadius();
    var center = circle.getCenter();
    return (google.maps.geometry.spherical.computeDistanceBetween(point, center) <= radius)
}

html, body {
            height: 200px;
            margin: 0;
            padding: 0;
        }

        #map {
            height: 100%;
        }

        .controls {
            margin-top: 10px;
            border: 1px solid transparent;
            border-radius: 2px 0 0 2px;
            box-sizing: border-box;
            -moz-box-sizing: border-box;
            height: 32px;
            outline: none;
            box-shadow: 0 2px 6px rgba(0, 0, 0, 0.3);
        }

        #pac-input {
            background-color: #fff;
            font-family: Roboto;
            font-size: 15px;
            font-weight: 300;
            margin-left: 12px;
            padding: 0 11px 0 13px;
            text-overflow: ellipsis;
            width: 300px;
        }

        #pac-input:focus {
                border-color: #4d90fe;
        }

        .pac-container {
            font-family: Roboto;
        }

 <input id="pac-input" class="controls" type="text" placeholder="Search Box">
 <div id="map"></div>
 <div id="output"/>
 <script src="https://maps.googleapis.com/maps/api/js?libraries=places&callback=initMap"
           async defer></script>

Check if coordinate exists in any of multiple circles in Google Maps

1 Answers1