mobility-toolbox-js/ol/utils/getGraphByZoom.js

Toolbox for JavaScript applications in the domains of mobility and logistics.

export const DEFAULT_GRAPH = 'osm';
export const DEFAULT_GRAPH_MAPPING = {
    1: DEFAULT_GRAPH,
};
/**
 * This function return which graph to use based on the current zoom level.
 *
 * The list of graphs available for a maplibre style is available in the style metadata.
 *
 * @param {number} zoom - The current zoom level of the map.
 * @param {StyleMetadataGraphs} styleMetadata - The style metadata containing the graph mapping.
 * @returns {string} - The graph to use for the given zoom level.
 */
export default function getGraphByZoom(zoom = 0, styleMetadata = DEFAULT_GRAPH_MAPPING) {
    var _a;
    const breakPoints = Object.keys(styleMetadata).map((k) => {
        return parseFloat(k);
    });
    const closest = breakPoints.reverse().find((bp) => {
        return bp <= Math.floor(zoom) - 1; // - 1 due to ol zoom !== mapbox zoom
    });
    let key = closest;
    key !== null && key !== void 0 ? key : (key = Math.min(...breakPoints));
    return (_a = styleMetadata[key]) !== null && _a !== void 0 ? _a : DEFAULT_GRAPH;
}