Add a generated icon to the map | Mapbox GL JS

This example uses addImage to generate an icon at runtime and add it to a map style. Then it adds the icon to the map by including the 'layout': {'icon-image': 'gradient'} statement inside addLayer.

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Add a generated icon to the map</title>
<meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no">
<link href="https://api.mapbox.com/mapbox-gl-js/v2.13.0/mapbox-gl.css" rel="stylesheet">
<script src="https://api.mapbox.com/mapbox-gl-js/v2.13.0/mapbox-gl.js"></script>
<style>
body { margin: 0; padding: 0; }
#map { position: absolute; top: 0; bottom: 0; width: 100%; }
</style>
</head>
<body>
<div id="map"></div>
 
<script>
	// TO MAKE THE MAP APPEAR YOU MUST
	// ADD YOUR ACCESS TOKEN FROM
	// https://account.mapbox.com
	mapboxgl.accessToken = 'YOUR_MAPBOX_ACCESS_TOKEN';
const map = new mapboxgl.Map({
container: 'map',
center: [0, 0],
zoom: 2,
// Choose from Mapbox's core styles, or make your own style with Mapbox Studio
style: 'mapbox://styles/mapbox/streets-v12'
});
 
map.on('load', () => {
const width = 64; // The image will be 64 pixels square
const bytesPerPixel = 4; // Each pixel is represented by 4 bytes: red, green, blue, and alpha.
const data = new Uint8Array(width * width * bytesPerPixel);
 
for (let x = 0; x < width; x++) {
for (let y = 0; y < width; y++) {
const offset = (y * width + x) * bytesPerPixel;
data[offset + 0] = (y / width) * 255; // red
data[offset + 1] = (x / width) * 255; // green
data[offset + 2] = 128; // blue
data[offset + 3] = 255; // alpha
}
}
 
map.addImage('gradient', { width: width, height: width, data: data });
 
map.addSource('point', {
'type': 'geojson',
'data': {
'type': 'FeatureCollection',
'features': [
{
'type': 'Feature',
'geometry': {
'type': 'Point',
'coordinates': [0, 0]
}
}
]
}
});
map.addLayer({
'id': 'points',
'type': 'symbol',
'source': 'point',
'layout': {
'icon-image': 'gradient'
}
});
});
</script>
 
</body>
</html>