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Add a generated icon to the map

Add an icon to the map that was generated at runtime.

<!DOCTYPE html>
<html lang="en">
<head>
    <title>Add a generated icon to the map</title>
    <meta property="og:description" content="Add an icon to the map that was generated at runtime." />
    <meta charset='utf-8'>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel='stylesheet' href='https://unpkg.com/[email protected]/dist/maplibre-gl.css' />
    <script src='https://unpkg.com/[email protected]/dist/maplibre-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 maplibregl.Map({
        container: 'map',
        style:
            'https://api.maptiler.com/maps/streets/style.json?key=get_your_own_OpIi9ZULNHzrESv6T2vL'
    });

    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, height: width, 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>