Create and style clusters
Use TrackAsia GL JS' built-in functions to visualize points as clusters.
<!DOCTYPE html>
<html lang="en">
<head>
<title>Create and style clusters</title>
<meta property="og:description" content="Use TrackAsia GL JS' built-in functions to visualize points as clusters." />
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<link rel="stylesheet" href="https://unpkg.com/[email protected]/dist/trackasia-gl.css" />
<script src="https://unpkg.com/[email protected]/dist/trackasia-gl.js"></script>
<style>
body {
margin: 0;
padding: 0;
}
html,
body,
#map {
height: 100%;
}
</style>
</head>
<body>
<div id="map"></div>
<script>
const map = new trackasiagl.Map({
container: "map",
style: "https://maps.track-asia.com/styles/v1/streets.json?key=public_key",
center: [-103.59179687498357, 40.66995747013945],
zoom: 3,
});
map.on("load", () => {
// Add a new source from our GeoJSON data and
// set the 'cluster' option to true. GL-JS will
// add the point_count property to your source data.
map.addSource("earthquakes", {
type: "geojson",
// Point to GeoJSON data. This example visualizes all M1.0+ earthquakes
// from 12/22/15 to 1/21/16 as logged by USGS' Earthquake hazards program.
data: "https://docs.track-asia.com/assets/earthquakes.geojson",
cluster: true,
clusterMaxZoom: 14, // Max zoom to cluster points on
clusterRadius: 50, // Radius of each cluster when clustering points (defaults to 50)
});
map.addLayer({
id: "clusters",
type: "circle",
source: "earthquakes",
filter: ["has", "point_count"],
paint: {
// Use step expressions (https://docs.track-asia.com/style/#expressions-step)
// with three steps to implement three types of circles:
// * Blue, 20px circles when point count is less than 100
// * Yellow, 30px circles when point count is between 100 and 750
// * Pink, 40px circles when point count is greater than or equal to 750
"circle-color": [
"step",
["get", "point_count"],
"#51bbd6",
100,
"#f1f075",
750,
"#f28cb1",
],
"circle-radius": [
"step",
["get", "point_count"],
20,
100,
30,
750,
40,
],
},
});
map.addLayer({
id: "cluster-count",
type: "symbol",
source: "earthquakes",
filter: ["has", "point_count"],
layout: {
"text-field": "{point_count_abbreviated}",
"text-font": [
"DIN Pro Regular",
"Arial Unicode MS Regular",
],
"text-size": 12,
},
});
map.addLayer({
id: "unclustered-point",
type: "circle",
source: "earthquakes",
filter: ["!", ["has", "point_count"]],
paint: {
"circle-color": "#11b4da",
"circle-radius": 4,
"circle-stroke-width": 1,
"circle-stroke-color": "#fff",
},
});
// inspect a cluster on click
map.on("click", "clusters", async (e) => {
const features = map.queryRenderedFeatures(e.point, {
layers: ["clusters"],
});
const clusterId = features[0].properties.cluster_id;
const zoom = await map
.getSource("earthquakes")
.getClusterExpansionZoom(clusterId);
map.easeTo({
center: features[0].geometry.coordinates,
zoom,
});
});
// When a click event occurs on a feature in
// the unclustered-point layer, open a popup at
// the location of the feature, with
// description HTML from its properties.
map.on("click", "unclustered-point", (e) => {
const coordinates =
e.features[0].geometry.coordinates.slice();
const mag = e.features[0].properties.mag;
let tsunami;
if (e.features[0].properties.tsunami === 1) {
tsunami = "yes";
} else {
tsunami = "no";
}
// Ensure that if the map is zoomed out such that
// multiple copies of the feature are visible, the
// popup appears over the copy being pointed to.
while (Math.abs(e.lngLat.lng - coordinates[0]) > 180) {
coordinates[0] += e.lngLat.lng > coordinates[0] ? 360 : -360;
}
new trackasiagl.Popup()
.setLngLat(coordinates)
.setHTML(
`magnitude: ${mag}<br>Was there a tsunami?: ${tsunami}`
)
.addTo(map);
});
map.on("mouseenter", "clusters", () => {
map.getCanvas().style.cursor = "pointer";
});
map.on("mouseleave", "clusters", () => {
map.getCanvas().style.cursor = "";
});
});
</script>
</body>
</html>