Leaflet – Changing GeoJSON Feature Draw Order

draw ordergeojsonleafletweb-mapping

I have county polygons in GeoJSON format. Obviously, some of the counties share an edge.

When a county is hovered over, the stroke and fill change to a red color.

The problem is that the stroke of some of the polygons is covered by the one next to it.

Is there a way to reorder the features so that the feature that is hovered over moves to the top?

I've seen that there's a bringToFront method, but that is for a layer, not a feature.

Any ideas?

Best Answer

You should really use the bringToFront method.

In Leaflet, everything is a layer (except controls), even when it is the representation of a GeoJSON feature. In the latter case, we are even talking about vector layers.

The bringToFront and bringToBack methods are specific to vector layers, so that you can re-order them within their SVG or Canvas container (whereas raster and HTML layers can get a CSS class with z-index for that purpose).

Demo: https://jsfiddle.net/3v7hd2vx/228/

Related Solutions

[GIS] How to modify features during runtime, in a GeoJSON feature group on Leaflet

I have written down a small code to modify geojson feature style on runtime using leaflet. you can try it on jsFiddle or use the following code test locally.

I hope it will help.

Here is the code:

<!DOCTYPE html>
<html>
<head>
<title>Leaflet Coloring Geojson Features</title>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link rel="stylesheet" href="http://leafletjs.com/dist/leaflet.css" />
<!--[if lte IE 8]><link rel="stylesheet" href="../dist/leaflet.ie.css" /><![endif]-->
<style>
#map {
    width: 800px;
    height: 500px;
}
.info {
    padding: 6px 8px;
    font: 14px/16px Arial, Helvetica, sans-serif;
    background: white;
    background: rgba(255, 255, 255, 0.8);
    box-shadow: 0 0 15px rgba(0, 0, 0, 0.2);
    border-radius: 5px;
}
.info h4 {
    margin: 0 0 5px;
    color: #777;
}
.legend {
    text-align: left;
    line-height: 18px;
    color: #555;
}
.legend i {
    width: 18px;
    height: 18px;
    float: left;
    margin-right: 8px;
    opacity: 0.7;
}
</style>
</head>
<body>
<div id="map"></div>
<script src="http://code.jquery.com/jquery-1.9.1.min.js"></script> 
<script src="http://leafletjs.com/dist/leaflet.js"></script> 
<script type="text/javascript" src="http://leafletjs.com/examples/us-states.js"></script> 
<script type="text/javascript">
    $(document).ready(function () {
        init_map();
        init_geojson();
        $("#btn").on('click', function () {
            var stateName = $('#statename').val();
            console.log(stateName);
            init_geojson(stateName);
        });
    });
    var map, geojson, sn;

    function init_map() {
        map = L.map('map').setView([37.8, -96], 4);
        L.tileLayer('http://{s}.tile.cloudmade.com/{key}/22677/256/{z}/{x}/{y}.png', {
            attribution: 'Map data &copy; 2011 OpenStreetMap contributors, Imagery &copy; 2012 CloudMade',
            key: 'BC9A493B41014CAABB98F0471D759707'
        }).addTo(map);
        geojson = L.geoJson(statesData, {
            style: style
            //onEachFeature: onEachFeature,
        }).addTo(map);
    }

    function init_geojson(n) {
        console.log(geojson.options);
        map.removeLayer(geojson);
        if (n != "") {
            sn = n;
            console.log(sn);
            geojson = L.geoJson(statesData, {
                style: style
            }).addTo(map);
        }
    }

    function style(feature) {
        console.log(sn);
        if (sn == feature.properties.name) {
            return {
                weight: 2,
                opacity: 1,
                color: 'white',
                dashArray: '3',
                fillOpacity: 0.3,
                fillColor: '#ff0000'
            };
        } else {
            return {
                weight: 2,
                opacity: 1,
                color: 'white',
                dashArray: '3',
                fillOpacity: 0.3,
                fillColor: '#666666'
            };
        }
    }
</script>
<input type="text" id="statename" value="Alaska">
<input type="button" id="btn" value="Set Color"/>
</body>
</html>

Leaflet – Using setStyle() Function for GeoJSON Features

This works without needing to remove the layer and recreate a new one as described above:

geojson_layer.eachLayer(function (layer) {  
  if(layer.feature.properties.NAME == 'feature 1') {    
    layer.setStyle({fillColor :'blue'}) 
  }
});

It seems to be quite a bit more efficient than removing and recreating the geoJson layer. From the docs, a GeoJSON layer extends FeatureGroup which in turn extends LayerGroup.
Additionally, it seems that each geoJson feature has its own layer in the FeatureGroup!

Best Answer

Related Solutions

[GIS] How to modify features during runtime, in a GeoJSON feature group on Leaflet

Leaflet – Using setStyle() Function for GeoJSON Features

Related Question