@geogirafe/lib-geoportal/tools/legendhelper.js

GeoGirafe is a flexible application to build online geoportals.

import { appendParams } from 'ol/uri';
class LegendHelper {
}
/**
 * Get the WMS legend URL.
 * @param url The base url of the wms service.
 * @param layerName The name of a wms layer.
 * @param options to create the legend url.
 * @returns The legend URL or undefined.
 */
Object.defineProperty(LegendHelper, "getWMSLegendURL", {
    enumerable: true,
    configurable: true,
    writable: true,
    value: (url, layerName, options) => {
        if (!url) {
            return undefined;
        }
        const queryString = {
            FORMAT: 'image/png',
            TRANSPARENT: true,
            SERVICE: 'WMS',
            VERSION: '1.1.1',
            REQUEST: 'GetLegendGraphic',
            LAYER: layerName
        };
        const scale = options?.scale;
        const legendRule = options?.legendRule;
        const legendWidth = options?.legendWidth;
        const legendHeight = options?.legendHeight;
        const serverType = options?.serverType;
        const dpi = options?.dpi;
        const bbox = options?.bbox;
        const srs = options?.srs;
        const additionalQueryString = options?.additionalQueryString;
        if (scale !== undefined) {
            queryString.SCALE = scale;
        }
        if (legendRule !== undefined) {
            queryString.RULE = legendRule;
            if (legendWidth !== undefined) {
                queryString.WIDTH = legendWidth;
            }
            if (legendHeight !== undefined) {
                queryString.HEIGHT = legendHeight;
            }
        }
        if (serverType == 'qgis') {
            if (dpi != undefined) {
                queryString.DPI = dpi;
            }
            if (bbox != undefined && srs != undefined && scale != undefined && dpi != undefined && legendRule == undefined) {
                queryString.BBOX = bbox.join(',');
                queryString.SRS = srs;
                queryString.SRCWIDTH = Math.round(((bbox[2] - bbox[0]) / scale) * 39.37 * dpi);
                queryString.SRCHEIGHT = Math.round(((bbox[3] - bbox[1]) / scale) * 39.37 * dpi);
                delete queryString.SCALE; // QGIS calculate it from the BBOX the SRCWIDTH and the SRCHEIGHT.
            }
        }
        if (additionalQueryString) {
            Object.assign(queryString, additionalQueryString);
        }
        return appendParams(url, queryString);
    }
});
/**
 * Retrieves the legend URL for a given WMTS tile layer.
 * @param {TileLayer<WMTS>} olayer - The OpenLayers tile layer object.
 * @returns The legend URL or undefined if not found.
 */
Object.defineProperty(LegendHelper, "getWMTSLegendURL", {
    enumerable: true,
    configurable: true,
    writable: true,
    value: (olayer) => {
        // BGE case of multiple styles ? case of multiple legendUrl ?
        const styles = olayer.get('capabilitiesStyles');
        if (!Array.isArray(styles) || styles.length <= 0) {
            return;
        }
        const legendURL = styles[0].LegendURL;
        if (!Array.isArray(legendURL) || legendURL.length <= 0) {
            return;
        }
        return legendURL[0].href;
    }
});
export default LegendHelper;