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PMTiles source and protocol

Uses the PM tiles plugin and protocol to present a map.

<!DOCTYPE html>
<html lang="en">
<head>
    <title>PMTiles source and protocol</title>
    <meta property="og:description" content="Uses the PM tiles plugin and protocol to present a map." />
    <meta charset='utf-8'>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel='stylesheet' href='https://unpkg.com/maplibre-gl@4.1.3/dist/maplibre-gl.css' />
    <script src='https://unpkg.com/maplibre-gl@4.1.3/dist/maplibre-gl.js'></script>
    <script src="https://unpkg.com/pmtiles@2.11.0/dist/index.js"></script>
    <style>
        body { margin: 0; padding: 0; }
        html, body, #map { height: 100%; }
    </style>
</head>
<body>
<div id="map"></div>
<script>

    // add the PMTiles plugin to the maplibregl global.
    const protocol = new pmtiles.Protocol();
    maplibregl.addProtocol('pmtiles', (request) => {
        return new Promise((resolve, reject) => {
            const callback = (err, data) => {
                if (err) {
                    reject(err);
                } else {
                    resolve({data});
                }
            };
            protocol.tile(request, callback);
        });
    });

    const PMTILES_URL = 'https://protomaps.github.io/PMTiles/protomaps(vector)ODbL_firenze.pmtiles';

    const p = new pmtiles.PMTiles(PMTILES_URL);

    // this is so we share one instance across the JS code and the map renderer
    protocol.add(p);

    // we first fetch the header so we can get the center lon, lat of the map.
    p.getHeader().then(h => {
        const map = new maplibregl.Map({
            container: 'map',
            zoom: h.maxZoom - 2,
            center: [h.centerLon, h.centerLat],
            style: {
                version: 8,
                sources: {
                    'example_source': {
                        type: 'vector',
                        url: `pmtiles://${PMTILES_URL}`,
                        attribution: '© <a href="https://openstreetmap.org">OpenStreetMap</a>'
                    }
                },
                layers: [
                    {
                        'id': 'buildings',
                        'source': 'example_source',
                        'source-layer': 'landuse',
                        'type': 'fill',
                        'paint': {
                            'fill-color': 'steelblue'
                        }
                    },
                    {
                        'id': 'roads',
                        'source': 'example_source',
                        'source-layer': 'roads',
                        'type': 'line',
                        'paint': {
                            'line-color': 'black'
                        }
                    },
                    {
                        'id': 'mask',
                        'source': 'example_source',
                        'source-layer': 'mask',
                        'type': 'fill',
                        'paint': {
                            'fill-color': 'white'
                        }
                    }
                ]
            }
        });
    });
</script>
</body>
</html>