@loaders.gl/pmtiles/dist/lib/parse-pmtiles.js

Framework-independent loader for the pmtiles format

// loaders.gl
// SPDX-License-Identifier: MIT
// Copyright (c) vis.gl contributors
import { TileJSONLoader } from '@loaders.gl/mvt';
// import {Source, PMTiles, Header, TileType} from 'pmtiles';
import * as pmtiles from 'pmtiles';
const { TileType } = pmtiles;
/**
 * Parse PMTiles metdata from a PMTiles file
 * @param header
 * @param tilejsonMetadata
 * @param options
 * @param loadOptions
 * @returns
 */
export function parsePMTilesHeader(header, pmtilesMetadata, options, loadOptions) {
    // Ironically, to use the TileJSON loader we need to stringify the metadata again.
    // This is the price of integrating with the existing pmtiles library.
    // TODO - provide a non-standard TileJSONLoader parsers that accepts a JSON object?
    let tilejson = null;
    if (pmtilesMetadata) {
        try {
            const string = JSON.stringify(pmtilesMetadata);
            tilejson = TileJSONLoader.parseTextSync?.(string, loadOptions) || null;
        }
        catch (error) {
            // eslint-disable-next-line no-console
            console.warn('PMTiles metadata could not be interpreted as TileJSON', error);
        }
    }
    const partialMetadata = {};
    if (typeof tilejson?.name === 'string') {
        partialMetadata.name = tilejson.name;
    }
    if (typeof tilejson?.htmlAttribution === 'string') {
        partialMetadata.attributions = [tilejson.htmlAttribution];
    }
    const metadata = {
        ...partialMetadata,
        format: 'pmtiles',
        formatVersion: header.specVersion,
        attributions: [],
        tileMIMEType: decodeTileType(header.tileType),
        minZoom: header.minZoom,
        maxZoom: header.maxZoom,
        boundingBox: [
            [header.minLon, header.minLat],
            [header.maxLon, header.maxLat]
        ],
        center: [header.centerLon, header.centerLat],
        centerZoom: header.centerZoom,
        etag: header.etag
    };
    if (tilejson) {
        metadata.tilejson = tilejson;
    }
    // Application can optionally include the raw header and metadata.
    if (options?.includeFormatHeader) {
        metadata.formatHeader = header;
        metadata.formatMetadata = metadata;
    }
    return metadata;
}
/** Extract a MIME type for tiles from vector tile header  */
function decodeTileType(tileType) {
    switch (tileType) {
        case TileType.Mvt:
            return 'application/vnd.mapbox-vector-tile';
        case TileType.Png:
            return 'image/png';
        case TileType.Jpeg:
            return 'image/jpeg';
        case TileType.Webp:
            return 'image/webp';
        case TileType.Avif:
            return 'image/avif';
        default:
            return 'application/octet-stream';
    }
}