s2-tools/dist/readers/fetch.js

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

/**
 * # Fetch Reader
 *
 * ## Description
 * The browser reader that fetches data from a URL.
 *
 * ## Usage
 * ```ts
 * import { FetchReader } from 's2-tools';
 *
 * const reader = new FetchReader('https://example.com/BETA2007.gsb', true);
 *
 * const data = await reader.getRange(0, 100);
 * ```
 */
export class FetchReader {
    path;
    rangeRequests;
    byteLength = 0;
    byteOffset = 0;
    /**
     * @param path - the location of the PMTiles data
     * @param rangeRequests - FetchReader specific; enable range requests or use urlParam "bytes"
     */
    constructor(path, rangeRequests) {
        this.path = path;
        this.rangeRequests = rangeRequests;
    }
    /**
     * Not applicable for FetchReader
     * @param _byteOffset - offset
     * @param _littleEndian - le or be
     * @returns - 0
     */
    getBigInt64(_byteOffset, _littleEndian) {
        return 0n;
    }
    /**
     * Not applicable for FetchReader
     * @param _byteOffset - offset
     * @param _littleEndian - le or be
     * @returns - 0
     */
    getBigUint64(_byteOffset, _littleEndian) {
        return 0n;
    }
    /**
     * Not applicable for FetchReader
     * @param _byteOffset - offset
     * @param _littleEndian - le or be
     * @returns - 0
     */
    getFloat32(_byteOffset, _littleEndian) {
        return 0;
    }
    /**
     * Not applicable for FetchReader
     * @param _byteOffset - offset
     * @param _littleEndian - le or be
     * @returns - 0
     */
    getFloat64(_byteOffset, _littleEndian) {
        return 0;
    }
    /**
     * Not applicable for FetchReader
     * @param _byteOffset - offset
     * @param _littleEndian - le or be
     * @returns - 0
     */
    getInt16(_byteOffset, _littleEndian) {
        return 0;
    }
    /**
     * Not applicable for FetchReader
     * @param _byteOffset - offset
     * @param _littleEndian - le or be
     * @returns - 0
     */
    getInt32(_byteOffset, _littleEndian) {
        return 0;
    }
    /**
     * Not applicable for FetchReader
     * @param _byteOffset - offset
     * @returns - 0
     */
    getInt8(_byteOffset) {
        return 0;
    }
    /**
     * Not applicable for FetchReader
     * @param _byteOffset - offset
     * @param _littleEndian - le or be
     * @returns - 0
     */
    getUint16(_byteOffset, _littleEndian) {
        return 0;
    }
    /**
     * Not applicable for FetchReader
     * @param _byteOffset - offset
     * @param _littleEndian - le or be
     * @returns - 0
     */
    getUint32(_byteOffset, _littleEndian) {
        return 0;
    }
    /**
     * Not applicable for FetchReader
     * @param _byteOffset - offset
     * @returns - 0
     */
    getUint8(_byteOffset) {
        return 0;
    }
    /**
     * Not applicable for FetchReader
     * @param _begin - beginning
     * @param _end - end
     * @returns - empty DataView
     */
    slice(_begin, _end) {
        return new DataView(new Uint8Array([]).buffer);
    }
    /**
     * Not applicable for FetchReader
     * @param _encoding - does nothing
     */
    setStringEncoding(_encoding) { }
    /**
     * Not applicable for FetchReader
     * @param _byteOffset - offset
     * @param _byteLength - length
     * @returns - empty string
     */
    parseString(_byteOffset, _byteLength) {
        return '';
    }
    /**
     * Reads a range from the file
     * @param offset - the offset of the range
     * @param length - the length of the range
     * @returns - the ranged buffer
     */
    async getRange(offset, length) {
        const bytes = String(offset) + '-' + (length !== undefined ? String(offset + length) : '');
        const fetchReq = this.rangeRequests
            ? fetch(this.path, {
                headers: { Range: `bytes=${offset}-${length === undefined ? '' : offset + length - 1}` },
            })
            : fetch(`${this.path}&bytes=${bytes}`);
        const res = await fetchReq.then(async (res) => await res.arrayBuffer());
        return new Uint8Array(res, 0, res.byteLength);
    }
}
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