s2-tools/dist/converters/toJSON/index.js

A collection of geospatial tools primarily designed for WGS84, Web Mercator, and S2.

import { convert } from '../../geometry/tools/convert';
import { mergeBBoxes } from '../../geometry';
/**
 * Given a writer and an array of iterators, write the input features to the writer as a JSON object
 *
 * Usage:
 * ```ts
 * import { toJSON, JSONReader } from 's2-tools'
 * import { FileReader, FileWriter } from 's2-tools/file'
 *
 * const fileReader = new FileReader(`${__dirname}/fixtures/points.geojson`);
 * const jsonReader = new JSONReader(fileReader);
 * const bufWriter = new FileWriter(`${__dirname}/fixtures/points2.geojson`);
 * await toJSON(bufWriter, [jsonReader], { projection: 'WM', buildBBox: true });
 * ```
 * @param writer - the writer to append strings to
 * @param iterators - the collection of iterators to write
 * @param opts - user defined options [optional]
 */
export async function toJSON(writer, iterators, opts) {
    const projection = opts?.projection ?? 'S2';
    const type = projection === 'S2' ? 'S2FeatureCollection' : 'FeatureCollection';
    const faces = new Set();
    const buildBBox = opts?.buildBBox ?? false;
    let bbox;
    const onFeature = opts?.onFeature ?? ((feature) => feature);
    await writer.appendString(`{\n\t"type": "${type}",\n`);
    await writer.appendString('\t"features": [\n');
    let first = true;
    for (const iterator of iterators) {
        for await (const feature of iterator) {
            const convertedFeatures = convert(projection, feature, buildBBox);
            for (const convertedFeature of convertedFeatures) {
                const userFeature = onFeature(convertedFeature);
                if (userFeature === undefined)
                    continue;
                faces.add(userFeature.face ?? 0);
                if (buildBBox && userFeature.geometry.bbox !== undefined)
                    bbox = mergeBBoxes(bbox, userFeature.geometry.bbox);
                if (!first)
                    await writer.appendString(',\n');
                first = false;
                await writer.appendString(`\t\t${JSON.stringify(userFeature)}`);
            }
        }
    }
    await writer.appendString('\n\t],');
    await writer.appendString(`\n\t"faces": ${JSON.stringify([...faces])}`);
    if (bbox !== undefined)
        await writer.appendString(`,\n\t"bbox": ${JSON.stringify(bbox)}`);
    await writer.appendString('\n}');
}
/**
 * Given a writer and an array of iterators, write the input features to the writer as JSON-LD
 *
 * Usage:
 * ```ts
 * import { toJSON, JSONReader } from 's2-tools'
 * import { FileReader, FileWriter } from 's2-tools/file'
 *
 * const fileReader = new FileReader(`${__dirname}/fixtures/points.geojson`);
 * const jsonReader = new JSONReader(fileReader);
 * const bufWriter = new FileWriter(`${__dirname}/fixtures/points.geojsonld`);
 * const onFeature = (feature) => {
 *  feature.metadata = { id: feature.id };
 *  return feature;
 * }
 * await toJSONLD(bufWriter, [jsonReader], { projection: 'S2', buildBBox: true, onFeature });
 * ```
 * @param writer - the writer to apppend strings to
 * @param iterators - the collection of iterators to write
 * @param opts - user defined options [optional]
 */
export async function toJSONLD(writer, iterators, opts) {
    const projection = opts?.projection ?? 'S2';
    const onFeature = opts?.onFeature ?? ((feature) => feature);
    const buildBBox = opts?.buildBBox ?? false;
    for (const iterator of iterators) {
        for await (const feature of iterator) {
            const convertedFeatures = convert(projection, feature, buildBBox);
            for (const convertedFeature of convertedFeatures) {
                const userFeature = onFeature(convertedFeature);
                if (userFeature === undefined)
                    continue;
                await writer.appendString(JSON.stringify(userFeature) + '\n');
            }
        }
    }
}
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