s2-tools/dist/readers/shapefile/index.js

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

import { BufferReader } from '..';
import { DataBaseFile } from './dbf';
import { ShapeFileReader } from './shp';
import { Transformer } from '../../proj4';
import { iterItems } from '../../util';
export * from './dbf';
export * from './shp';
/**
 * Assumes the input is pointing to shapefile data.
 * @param input - raw buffer of gzipped data (folder of shp, dbf, prj, and/or cpg)
 * @param defs - optional array of ProjectionTransformDefinitions to insert
 * @param epsgCodes - a record of EPSG codes to use for the transformer if needed
 * @returns - a Shapefile
 */
export async function shapefileFromGzip(input, defs, epsgCodes) {
    let encoding = 'utf8';
    let transform = undefined;
    let dbfReader = undefined;
    let shpData = undefined;
    for (const item of iterItems(new Uint8Array(input))) {
        if (item.filename.endsWith('cpg')) {
            encoding = new TextDecoder('utf8').decode(await item.read());
        }
        else if (item.filename.endsWith('dbf')) {
            const data = await item.read();
            dbfReader = new DataBaseFile(new BufferReader(data.buffer), encoding);
        }
        else if (item.filename.endsWith('shp')) {
            shpData = await item.read();
        }
        else if (item.filename.endsWith('prj')) {
            const data = await item.read();
            transform = new Transformer(new TextDecoder('utf8').decode(data));
            if (defs !== undefined) {
                for (const def of defs)
                    transform.insertDefinition(def);
            }
            if (epsgCodes !== undefined) {
                for (const [key, value] of Object.entries(epsgCodes))
                    transform.insertEPSGCode(key, value);
            }
        }
    }
    if (shpData === undefined)
        throw new Error('Shapefile not found');
    return new ShapeFileReader(new BufferReader(shpData.buffer), dbfReader, transform);
}
/**
 * Assumes the input is pointing to shapefile data or a gzipped folder with .shp, .dbf, .prj, and/or .cpg
 * @param url - the url to the shapefile
 * @returns - a Shapefile
 */
export async function shapefileFromURL(url) {
    const data = await fetchShapefile(url);
    if (url.endsWith('.zip'))
        return shapefileFromGzip(data);
    return new ShapeFileReader(new BufferReader(data));
}
/**
 * Fetches a shapefile or gzipped folder
 * @param url - the url to the shapefile
 * @returns - raw data of a shapefile OR a gzipped folder that may include the dbf, prj, and/or cpg
 */
async function fetchShapefile(url) {
    return await fetch(url)
        .then(async (res) => {
        if (!res.ok)
            throw new Error(`Failed to fetch data from ${url}`);
        return await res.arrayBuffer();
    })
        .catch((err) => {
        throw new Error(`Failed to fetch data from ${url}: ${err}`);
    });
}
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