Label decluttering on polygons.
Decluttering is used to avoid overlapping labels. The overflow: true
setting on the text style makes it so labels that do not fit within the bounds of a polygon are also considered for decluttering.
import 'ol/ol.css';
import GeoJSON from 'ol/format/GeoJSON';
import Map from 'ol/Map';
import VectorLayer from 'ol/layer/Vector';
import VectorSource from 'ol/source/Vector';
import View from 'ol/View';
import {Fill, Stroke, Style, Text} from 'ol/style';
const map = new Map({
target: 'map',
view: new View({
center: [0, 0],
zoom: 1,
}),
});
const labelStyle = new Style({
text: new Text({
font: '12px Calibri,sans-serif',
overflow: true,
fill: new Fill({
color: '#000',
}),
stroke: new Stroke({
color: '#fff',
width: 3,
}),
}),
});
const countryStyle = new Style({
fill: new Fill({
color: 'rgba(255, 255, 255, 0.6)',
}),
stroke: new Stroke({
color: '#319FD3',
width: 1,
}),
});
const style = [countryStyle, labelStyle];
const vectorLayer = new VectorLayer({
source: new VectorSource({
url: 'data/geojson/countries.geojson',
format: new GeoJSON(),
}),
style: function (feature) {
labelStyle.getText().setText(feature.get('name'));
return style;
},
declutter: true,
});
map.addLayer(vectorLayer);
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Vector Label Decluttering</title>
<!-- Pointer events polyfill for old browsers, see https://caniuse.com/#feat=pointer -->
<script src="https://unpkg.com/elm-pep"></script>
<!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
<script src="https://cdn.polyfill.io/v3/polyfill.min.js?features=fetch,requestAnimationFrame,Element.prototype.classList,URL,TextDecoder,Number.isInteger"></script>
<script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=Set""></script>
<style>
.map {
width: 100%;
height:400px;
}
</style>
</head>
<body>
<div id="map" class="map"></div>
<script src="main.js"></script>
</body>
</html>
{
"name": "vector-label-decluttering",
"dependencies": {
"ol": "6.6.1"
},
"devDependencies": {
"parcel": "^2.0.0-beta.1"
},
"scripts": {
"start": "parcel index.html",
"build": "parcel build --public-url . index.html"
}
}