Files
openlayers/src/ol/format/WKB.js
2022-07-19 23:24:22 +02:00

927 lines
25 KiB
JavaScript

/**
* @module ol/format/WKB
*/
import Feature from '../Feature.js';
import FeatureFormat, {transformGeometryWithOptions} from './Feature.js';
import GeometryCollection from '../geom/GeometryCollection.js';
import LineString from '../geom/LineString.js';
import MultiLineString from '../geom/MultiLineString.js';
import MultiPoint from '../geom/MultiPoint.js';
import MultiPolygon from '../geom/MultiPolygon.js';
import Point from '../geom/Point.js';
import Polygon from '../geom/Polygon.js';
import {get as getProjection} from '../proj.js';
import SimpleGeometry from '../geom/SimpleGeometry.js';
import {assign} from '../obj.js';
// WKB spec: https://www.ogc.org/standards/sfa
// EWKB spec: https://raw.githubusercontent.com/postgis/postgis/2.1.0/doc/ZMSgeoms.txt
/**
* @const
* @enum {number}
*/
const WKBGeometryType = {
POINT: 1,
LINE_STRING: 2,
POLYGON: 3,
MULTI_POINT: 4,
MULTI_LINE_STRING: 5,
MULTI_POLYGON: 6,
GEOMETRY_COLLECTION: 7,
/*
CIRCULAR_STRING: 8,
COMPOUND_CURVE: 9,
CURVE_POLYGON: 10,
MULTI_CURVE: 11,
MULTI_SURFACE: 12,
CURVE: 13,
SURFACE: 14,
*/
POLYHEDRAL_SURFACE: 15,
TIN: 16,
TRIANGLE: 17,
};
class WkbReader {
/**
* @param {DataView} view source to read
*/
constructor(view) {
/** @private */
this.view_ = view;
/**
* @type {number}
* @private
*/
this.pos_ = 0;
/**
* @type {boolean}
* @private
*/
this.initialized_ = false;
/**
* @type {boolean}
* @private
*/
this.isLittleEndian_ = false;
/**
* @type {boolean}
* @private
*/
this.hasZ_ = false;
/**
* @type {boolean}
* @private
*/
this.hasM_ = false;
/**
* @type {number|null}
* @private
*/
this.srid_ = null;
/**
* @type {import("../geom/Geometry.js").GeometryLayout}
* @private
*/
this.layout_ = 'XY';
}
/**
* @return {number} value
*/
readUint8() {
return this.view_.getUint8(this.pos_++);
}
/**
* @param {boolean} [isLittleEndian] Whether read value as little endian
* @return {number} value
*/
readUint32(isLittleEndian) {
return this.view_.getUint32(
(this.pos_ += 4) - 4,
isLittleEndian !== undefined ? isLittleEndian : this.isLittleEndian_
);
}
/**
* @param {boolean} [isLittleEndian] Whether read value as little endian
* @return {number} value
*/
readDouble(isLittleEndian) {
return this.view_.getFloat64(
(this.pos_ += 8) - 8,
isLittleEndian !== undefined ? isLittleEndian : this.isLittleEndian_
);
}
/**
* @return {import('../coordinate.js').Coordinate} coords for Point
*/
readPoint() {
/** @type import('../coordinate.js').Coordinate */
const coords = [];
coords.push(this.readDouble());
coords.push(this.readDouble());
if (this.hasZ_) {
coords.push(this.readDouble());
}
if (this.hasM_) {
coords.push(this.readDouble());
}
return coords;
}
/**
* @return {Array<import('../coordinate.js').Coordinate>} coords for LineString / LinearRing
*/
readLineString() {
const numPoints = this.readUint32();
/** @type Array<import('../coordinate.js').Coordinate> */
const coords = [];
for (let i = 0; i < numPoints; i++) {
coords.push(this.readPoint());
}
return coords;
}
/**
* @return {Array<Array<import('../coordinate.js').Coordinate>>} coords for Polygon like
*/
readPolygon() {
const numRings = this.readUint32();
/** @type Array<Array<import('../coordinate.js').Coordinate>> */
const rings = [];
for (let i = 0; i < numRings; i++) {
rings.push(this.readLineString()); // as a LinearRing
}
return rings;
}
/**
* @param {number} [expectedTypeId] Expected WKB Type ID
* @return {number} WKB Type ID
*/
readWkbHeader(expectedTypeId) {
const byteOrder = this.readUint8();
const isLittleEndian = byteOrder > 0;
const wkbType = this.readUint32(isLittleEndian);
const wkbTypeThousandth = Math.floor((wkbType & 0x0fffffff) / 1000);
const hasZ =
Boolean(wkbType & 0x80000000) ||
wkbTypeThousandth === 1 ||
wkbTypeThousandth === 3;
const hasM =
Boolean(wkbType & 0x40000000) ||
wkbTypeThousandth === 2 ||
wkbTypeThousandth === 3;
const hasSRID = Boolean(wkbType & 0x20000000);
const typeId = (wkbType & 0x0fffffff) % 1000; // Assume 1000 is an upper limit for type ID
const layout = /** @type {import("../geom/Geometry.js").GeometryLayout} */ (
['XY', hasZ ? 'Z' : '', hasM ? 'M' : ''].join('')
);
const srid = hasSRID ? this.readUint32(isLittleEndian) : null;
if (expectedTypeId !== undefined && expectedTypeId !== typeId) {
throw new Error('Unexpected WKB geometry type ' + typeId);
}
if (this.initialized_) {
// sanity checks
if (this.isLittleEndian_ !== isLittleEndian) {
throw new Error('Inconsistent endian');
}
if (this.layout_ !== layout) {
throw new Error('Inconsistent geometry layout');
}
if (srid && this.srid_ !== srid) {
throw new Error('Inconsistent coordinate system (SRID)');
}
} else {
this.isLittleEndian_ = isLittleEndian;
this.hasZ_ = hasZ;
this.hasM_ = hasM;
this.layout_ = layout;
this.srid_ = srid;
this.initialized_ = true;
}
return typeId;
}
/**
* @param {number} typeId WKB Type ID
* @return {any} values read
*/
readWkbPayload(typeId) {
switch (typeId) {
case WKBGeometryType.POINT:
return this.readPoint();
case WKBGeometryType.LINE_STRING:
return this.readLineString();
case WKBGeometryType.POLYGON:
case WKBGeometryType.TRIANGLE:
return this.readPolygon();
case WKBGeometryType.MULTI_POINT:
return this.readMultiPoint();
case WKBGeometryType.MULTI_LINE_STRING:
return this.readMultiLineString();
case WKBGeometryType.MULTI_POLYGON:
case WKBGeometryType.POLYHEDRAL_SURFACE:
case WKBGeometryType.TIN:
return this.readMultiPolygon();
case WKBGeometryType.GEOMETRY_COLLECTION:
return this.readGeometryCollection();
default:
throw new Error(
'Unsupported WKB geometry type ' + typeId + ' is found'
);
}
}
/**
* @param {number} expectedTypeId Expected WKB Type ID
* @return {any} values read
*/
readWkbBlock(expectedTypeId) {
return this.readWkbPayload(this.readWkbHeader(expectedTypeId));
}
/**
* @param {Function} reader reader function for each item
* @param {number} [expectedTypeId] Expected WKB Type ID
* @return {any} values read
*/
readWkbCollection(reader, expectedTypeId) {
const num = this.readUint32();
const items = [];
for (let i = 0; i < num; i++) {
const result = reader.call(this, expectedTypeId);
if (result) {
items.push(result);
}
}
return items;
}
/**
* @return {Array<import('../coordinate.js').Coordinate>} coords for MultiPoint
*/
readMultiPoint() {
return this.readWkbCollection(this.readWkbBlock, WKBGeometryType.POINT);
}
/**
* @return {Array<Array<import('../coordinate.js').Coordinate>>} coords for MultiLineString like
*/
readMultiLineString() {
return this.readWkbCollection(
this.readWkbBlock,
WKBGeometryType.LINE_STRING
);
}
/**
* @return {Array<Array<Array<import('../coordinate.js').Coordinate>>>} coords for MultiPolygon like
*/
readMultiPolygon() {
return this.readWkbCollection(this.readWkbBlock, WKBGeometryType.POLYGON);
}
/**
* @return {Array<import('../geom/Geometry.js').default>} array of geometries
*/
readGeometryCollection() {
return this.readWkbCollection(this.readGeometry);
}
/**
* @return {import('../geom/Geometry.js').default} geometry
*/
readGeometry() {
const typeId = this.readWkbHeader();
const result = this.readWkbPayload(typeId);
switch (typeId) {
case WKBGeometryType.POINT:
return new Point(
/** @type {import('../coordinate.js').Coordinate} */ (result),
this.layout_
);
case WKBGeometryType.LINE_STRING:
return new LineString(
/** @type {Array<import('../coordinate.js').Coordinate>} */ (result),
this.layout_
);
case WKBGeometryType.POLYGON:
case WKBGeometryType.TRIANGLE:
return new Polygon(
/** @type {Array<Array<import('../coordinate.js').Coordinate>>} */ (
result
),
this.layout_
);
case WKBGeometryType.MULTI_POINT:
return new MultiPoint(
/** @type {Array<import('../coordinate.js').Coordinate>} */ (result),
this.layout_
);
case WKBGeometryType.MULTI_LINE_STRING:
return new MultiLineString(
/** @type {Array<Array<import('../coordinate.js').Coordinate>>} */ (
result
),
this.layout_
);
case WKBGeometryType.MULTI_POLYGON:
case WKBGeometryType.POLYHEDRAL_SURFACE:
case WKBGeometryType.TIN:
return new MultiPolygon(
/** @type {Array<Array<Array<import('../coordinate.js').Coordinate>>>} */ (
result
),
this.layout_
);
case WKBGeometryType.GEOMETRY_COLLECTION:
return new GeometryCollection(
/** @type {Array<import('../geom/Geometry.js').default>} */ (result)
);
default:
return null;
}
}
/**
* @return {number|null} SRID in the EWKB. `null` if not defined.
*/
getSrid() {
return this.srid_;
}
}
class WkbWriter {
/**
* @type {Object}
* @property {string} [layout] geometryLayout
* @property {boolean} [littleEndian=true] littleEndian
* @property {boolean} [ewkb=true] Whether writes in EWKB format
* @property {Object} [nodata] NoData value for each axes
* @param {Object} opts options
*/
constructor(opts) {
opts = opts || {};
/** @type {string} */
this.layout_ = opts.layout;
this.isLittleEndian_ = opts.littleEndian !== false;
this.isEWKB_ = opts.ewkb !== false;
/** @type {Array<Array<number>>} */
this.writeQueue_ = [];
/**
* @type {Object}
* @property {number} X NoData value for X
* @property {number} Y NoData value for Y
* @property {number} Z NoData value for Z
* @property {number} M NoData value for M
*/
this.nodata_ = assign({X: 0, Y: 0, Z: 0, M: 0}, opts.nodata);
}
/**
* @param {number} value value
*/
writeUint8(value) {
this.writeQueue_.push([1, value]);
}
/**
* @param {number} value value
*/
writeUint32(value) {
this.writeQueue_.push([4, value]);
}
/**
* @param {number} value value
*/
writeDouble(value) {
this.writeQueue_.push([8, value]);
}
/**
* @param {import('../coordinate.js').Coordinate} coords coords
* @param {import("../geom/Geometry.js").GeometryLayout} layout layout
*/
writePoint(coords, layout) {
/**
* @type {Object}
* @property {number} X NoData value for X
* @property {number} Y NoData value for Y
* @property {number} [Z] NoData value for Z
* @property {number} [M] NoData value for M
*/
const coordsObj = assign.apply(
null,
layout.split('').map((axis, idx) => ({[axis]: coords[idx]}))
);
for (const axis of this.layout_) {
this.writeDouble(
axis in coordsObj ? coordsObj[axis] : this.nodata_[axis]
);
}
}
/**
* @param {Array<import('../coordinate.js').Coordinate>} coords coords
* @param {import("../geom/Geometry.js").GeometryLayout} layout layout
*/
writeLineString(coords, layout) {
this.writeUint32(coords.length); // numPoints
for (let i = 0; i < coords.length; i++) {
this.writePoint(coords[i], layout);
}
}
/**
* @param {Array<Array<import('../coordinate.js').Coordinate>>} rings rings
* @param {import("../geom/Geometry.js").GeometryLayout} layout layout
*/
writePolygon(rings, layout) {
this.writeUint32(rings.length); // numRings
for (let i = 0; i < rings.length; i++) {
this.writeLineString(rings[i], layout); // as a LinearRing
}
}
/**
* @param {number} wkbType WKB Type ID
* @param {number} [srid] SRID
*/
writeWkbHeader(wkbType, srid) {
wkbType %= 1000; // Assume 1000 is an upper limit for type ID
if (this.layout_.indexOf('Z') >= 0) {
wkbType += this.isEWKB_ ? 0x80000000 : 1000;
}
if (this.layout_.indexOf('M') >= 0) {
wkbType += this.isEWKB_ ? 0x40000000 : 2000;
}
if (this.isEWKB_ && Number.isInteger(srid)) {
wkbType |= 0x20000000;
}
this.writeUint8(this.isLittleEndian_ ? 1 : 0);
this.writeUint32(wkbType);
if (this.isEWKB_ && Number.isInteger(srid)) {
this.writeUint32(srid);
}
}
/**
* @param {Array<import('../coordinate.js').Coordinate>} coords coords
* @param {import("../geom/Geometry.js").GeometryLayout} layout layout
*/
writeMultiPoint(coords, layout) {
this.writeUint32(coords.length); // numItems
for (let i = 0; i < coords.length; i++) {
this.writeWkbHeader(1);
this.writePoint(coords[i], layout);
}
}
/**
* @param {Array<Array<import('../coordinate.js').Coordinate>>} coords coords
* @param {import("../geom/Geometry.js").GeometryLayout} layout layout
*/
writeMultiLineString(coords, layout) {
this.writeUint32(coords.length); // numItems
for (let i = 0; i < coords.length; i++) {
this.writeWkbHeader(2);
this.writeLineString(coords[i], layout);
}
}
/**
* @param {Array<Array<Array<import('../coordinate.js').Coordinate>>>} coords coords
* @param {import("../geom/Geometry.js").GeometryLayout} layout layout
*/
writeMultiPolygon(coords, layout) {
this.writeUint32(coords.length); // numItems
for (let i = 0; i < coords.length; i++) {
this.writeWkbHeader(3);
this.writePolygon(coords[i], layout);
}
}
/**
* @param {Array<import('../geom/Geometry.js').default>} geometries geometries
*/
writeGeometryCollection(geometries) {
this.writeUint32(geometries.length); // numItems
for (let i = 0; i < geometries.length; i++) {
this.writeGeometry(geometries[i]);
}
}
/**
* @param {import("../geom/Geometry.js").default} geom geometry
* @param {import("../geom/Geometry.js").GeometryLayout} [layout] layout
* @return {import("../geom/Geometry.js").GeometryLayout} minumum layout made by common axes
*/
findMinimumLayout(geom, layout = 'XYZM') {
/**
* @param {import("../geom/Geometry.js").GeometryLayout} a A
* @param {import("../geom/Geometry.js").GeometryLayout} b B
* @return {import("../geom/Geometry.js").GeometryLayout} minumum layout made by common axes
*/
const GeometryLayout_min = (a, b) => {
if (a === b) {
return a;
}
if (a === 'XYZM') {
// anything `b` is minimum
return b;
}
if (b === 'XYZM') {
// anything `a` is minimum
return a;
}
// otherwise, incompatible
return 'XY';
};
if (geom instanceof SimpleGeometry) {
return GeometryLayout_min(geom.getLayout(), layout);
}
if (geom instanceof GeometryCollection) {
const geoms = geom.getGeometriesArray();
for (let i = 0; i < geoms.length && layout !== 'XY'; i++) {
layout = this.findMinimumLayout(geoms[i], layout);
}
}
return layout;
}
/**
* @param {import("../geom/Geometry.js").default} geom geometry
* @param {number} [srid] SRID
*/
writeGeometry(geom, srid) {
/**
* @type {Object<import("../geom/Geometry.js").Type, WKBGeometryType>}
*/
const wkblut = {
Point: WKBGeometryType.POINT,
LineString: WKBGeometryType.LINE_STRING,
Polygon: WKBGeometryType.POLYGON,
MultiPoint: WKBGeometryType.MULTI_POINT,
MultiLineString: WKBGeometryType.MULTI_LINE_STRING,
MultiPolygon: WKBGeometryType.MULTI_POLYGON,
GeometryCollection: WKBGeometryType.GEOMETRY_COLLECTION,
};
const geomType = geom.getType();
const typeId = wkblut[geomType];
if (!typeId) {
throw new Error('GeometryType ' + geomType + ' is not supported');
}
// first call of writeGeometry() traverse whole geometries to determine its output layout if not specified on constructor.
if (!this.layout_) {
this.layout_ = this.findMinimumLayout(geom);
}
this.writeWkbHeader(typeId, srid);
if (geom instanceof SimpleGeometry) {
const writerLUT = {
Point: this.writePoint,
LineString: this.writeLineString,
Polygon: this.writePolygon,
MultiPoint: this.writeMultiPoint,
MultiLineString: this.writeMultiLineString,
MultiPolygon: this.writeMultiPolygon,
};
writerLUT[geomType].call(this, geom.getCoordinates(), geom.getLayout());
} else if (geom instanceof GeometryCollection) {
this.writeGeometryCollection(geom.getGeometriesArray());
}
}
getBuffer() {
const byteLength = this.writeQueue_.reduce((acc, item) => acc + item[0], 0);
const buffer = new ArrayBuffer(byteLength);
const view = new DataView(buffer);
let pos = 0;
this.writeQueue_.forEach((item) => {
switch (item[0]) {
case 1:
view.setUint8(pos, item[1]);
break;
case 4:
view.setUint32(pos, item[1], this.isLittleEndian_);
break;
case 8:
view.setFloat64(pos, item[1], this.isLittleEndian_);
break;
default:
break;
}
pos += item[0];
});
return buffer;
}
}
/**
* @typedef {Object} Options
* @property {boolean} [splitCollection=false] Whether to split GeometryCollections into multiple features on reading.
* @property {boolean} [hex=true] Returns hex string instead of ArrayBuffer for output. This also is used as a hint internally whether it should load contents as text or ArrayBuffer on reading.
* @property {boolean} [littleEndian=true] Use littleEndian for output.
* @property {boolean} [ewkb=true] Use EWKB format for output.
* @property {import("../geom/Geometry.js").GeometryLayout} [geometryLayout=null] Use specific coordinate layout for output features (null: auto detect)
* @property {number} [nodataZ=0] If the `geometryLayout` doesn't match with geometry to be output, this value is used to fill missing coordinate value of Z.
* @property {number} [nodataM=0] If the `geometryLayout` doesn't match with geometry to be output, this value is used to fill missing coordinate value of M.
* @property {number|boolean} [srid=true] SRID for output. Specify integer value to enforce the value as a SRID. Specify `true` to extract from `dataProjection`. `false` to suppress the output. This option only takes effect when `ewkb` is `true`.
*/
/**
* @classdesc
* Geometry format for reading and writing data in the `Well-Known Binary` (WKB) format.
* Also supports `Extended Well-Known Binary` (EWKB) format, used in PostGIS for example.
*
* @api
*/
class WKB extends FeatureFormat {
/**
* @param {Options} [opt_options] Optional configuration object.
*/
constructor(opt_options) {
super();
const options = opt_options ? opt_options : {};
this.splitCollection = Boolean(options.splitCollection);
this.viewCache_ = null;
this.hex_ = options.hex !== false;
this.littleEndian_ = options.littleEndian !== false;
this.ewkb_ = options.ewkb !== false;
this.layout_ = options.geometryLayout; // null for auto detect
this.nodataZ_ = options.nodataZ || 0;
this.nodataM_ = options.nodataM || 0;
this.srid_ = options.srid;
}
/**
* @return {import("./Feature.js").Type} Format.
*/
getType() {
return this.hex_ ? 'text' : 'arraybuffer';
}
/**
* Read a single feature from a source.
*
* @param {string|ArrayBuffer|ArrayBufferView} source Source.
* @param {import("./Feature.js").ReadOptions} [opt_options] Read options.
* @return {import("../Feature.js").default} Feature.
* @api
*/
readFeature(source, opt_options) {
return new Feature({
geometry: this.readGeometry(source, opt_options),
});
}
/**
* Read all features from a source.
*
* @param {string|ArrayBuffer|ArrayBufferView} source Source.
* @param {import("./Feature.js").ReadOptions} [opt_options] Read options.
* @return {Array<import("../Feature.js").default>} Features.
* @api
*/
readFeatures(source, opt_options) {
let geometries = [];
const geometry = this.readGeometry(source, opt_options);
if (this.splitCollection && geometry instanceof GeometryCollection) {
geometries = geometry.getGeometriesArray();
} else {
geometries = [geometry];
}
return geometries.map((geometry) => new Feature({geometry}));
}
/**
* Read a single geometry from a source.
*
* @param {string|ArrayBuffer|ArrayBufferView} source Source.
* @param {import("./Feature.js").ReadOptions} [opt_options] Read options.
* @return {import("../geom/Geometry.js").default} Geometry.
* @api
*/
readGeometry(source, opt_options) {
const view = getDataView(source);
if (!view) {
return null;
}
const reader = new WkbReader(view);
const geometry = reader.readGeometry();
this.viewCache_ = view; // cache for internal subsequent call of readProjection()
const options = this.getReadOptions(source, opt_options);
this.viewCache_ = null; // release
return transformGeometryWithOptions(geometry, false, options);
}
/**
* Read the projection from a source.
*
* @param {string|ArrayBuffer|ArrayBufferView} source Source.
* @return {import("../proj/Projection.js").default|undefined} Projection.
* @api
*/
readProjection(source) {
const view = this.viewCache_ || getDataView(source);
if (!view) {
return undefined;
}
const reader = new WkbReader(view);
reader.readWkbHeader();
return (
(reader.getSrid() && getProjection('EPSG:' + reader.getSrid())) ||
undefined
);
}
/**
* Encode a feature in this format.
*
* @param {import("../Feature.js").default} feature Feature.
* @param {import("./Feature.js").WriteOptions} [opt_options] Write options.
* @return {string|ArrayBuffer} Result.
* @api
*/
writeFeature(feature, opt_options) {
return this.writeGeometry(feature.getGeometry(), opt_options);
}
/**
* Encode an array of features in this format.
*
* @param {Array<import("../Feature.js").default>} features Features.
* @param {import("./Feature.js").WriteOptions} [opt_options] Write options.
* @return {string|ArrayBuffer} Result.
* @api
*/
writeFeatures(features, opt_options) {
return this.writeGeometry(
new GeometryCollection(features.map((f) => f.getGeometry())),
opt_options
);
}
/**
* Write a single geometry in this format.
*
* @param {import("../geom/Geometry.js").default} geometry Geometry.
* @param {import("./Feature.js").WriteOptions} [opt_options] Write options.
* @return {string|ArrayBuffer} Result.
* @api
*/
writeGeometry(geometry, opt_options) {
const options = this.adaptOptions(opt_options);
const writer = new WkbWriter({
layout: this.layout_,
littleEndian: this.littleEndian_,
ewkb: this.ewkb_,
nodata: {
Z: this.nodataZ_,
M: this.nodataM_,
},
});
// extract SRID from `dataProjection`
let srid = Number.isInteger(this.srid_) ? Number(this.srid_) : null;
if (this.srid_ !== false && !Number.isInteger(this.srid_)) {
const dataProjection =
options.dataProjection && getProjection(options.dataProjection);
if (dataProjection) {
const code = dataProjection.getCode();
if (code.indexOf('EPSG:') === 0) {
srid = Number(code.substring(5));
}
}
}
writer.writeGeometry(
transformGeometryWithOptions(geometry, true, options),
srid
);
const buffer = writer.getBuffer();
return this.hex_ ? encodeHexString(buffer) : buffer;
}
}
/**
* @param {ArrayBuffer} buffer source buffer
* @return {string} encoded hex string
*/
function encodeHexString(buffer) {
const view = new Uint8Array(buffer);
return Array.from(view.values())
.map((x) => (x < 16 ? '0' : '') + Number(x).toString(16).toUpperCase())
.join('');
}
/**
* @param {string} text source text
* @return {DataView} decoded binary buffer
*/
function decodeHexString(text) {
const buffer = new Uint8Array(text.length / 2);
for (let i = 0; i < text.length / 2; i++) {
buffer[i] = parseInt(text.substr(i * 2, 2), 16);
}
return new DataView(buffer.buffer);
}
/**
* @param {string | ArrayBuffer | ArrayBufferView} source source
* @return {DataView} data view
*/
function getDataView(source) {
if (typeof source === 'string') {
return decodeHexString(source);
} else if (ArrayBuffer.isView(source)) {
if (source instanceof DataView) {
return source;
}
return new DataView(source.buffer, source.byteOffset, source.byteLength);
} else if (source instanceof ArrayBuffer) {
return new DataView(source);
} else {
return null;
}
}
export default WKB;