135 lines
4.1 KiB
JavaScript
Executable File
135 lines
4.1 KiB
JavaScript
Executable File
import clone from '@turf/clone';
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import booleanClockwise from '@turf/boolean-clockwise';
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import { featureEach, geomEach } from '@turf/meta';
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import { getCoords } from '@turf/invariant';
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import { isObject, featureCollection } from '@turf/helpers';
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/**
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* Rewind {@link LineString|(Multi)LineString} or {@link Polygon|(Multi)Polygon} outer ring counterclockwise and inner rings clockwise (Uses {@link http://en.wikipedia.org/wiki/Shoelace_formula|Shoelace Formula}).
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*
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* @name rewind
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* @param {GeoJSON} geojson input GeoJSON Polygon
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* @param {Object} [options={}] Optional parameters
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* @param {boolean} [options.reverse=false] enable reverse winding
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* @param {boolean} [options.mutate=false] allows GeoJSON input to be mutated (significant performance increase if true)
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* @returns {GeoJSON} rewind Polygon
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* @example
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* var polygon = turf.polygon([[[121, -29], [138, -29], [138, -18], [121, -18], [121, -29]]]);
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*
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* var rewind = turf.rewind(polygon);
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*
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* //addToMap
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* var addToMap = [rewind];
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*/
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function rewind(geojson, options) {
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// Optional parameters
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options = options || {};
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if (!isObject(options)) throw new Error("options is invalid");
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var reverse = options.reverse || false;
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var mutate = options.mutate || false;
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// validation
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if (!geojson) throw new Error("<geojson> is required");
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if (typeof reverse !== "boolean")
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throw new Error("<reverse> must be a boolean");
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if (typeof mutate !== "boolean")
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throw new Error("<mutate> must be a boolean");
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// prevent input mutation
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if (mutate === false) geojson = clone(geojson);
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// Support Feature Collection or Geometry Collection
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var results = [];
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switch (geojson.type) {
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case "GeometryCollection":
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geomEach(geojson, function (geometry) {
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rewindFeature(geometry, reverse);
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});
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return geojson;
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case "FeatureCollection":
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featureEach(geojson, function (feature) {
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featureEach(rewindFeature(feature, reverse), function (result) {
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results.push(result);
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});
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});
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return featureCollection(results);
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}
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// Support Feature or Geometry Objects
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return rewindFeature(geojson, reverse);
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}
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/**
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* Rewind
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*
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* @private
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* @param {Geometry|Feature<any>} geojson Geometry or Feature
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* @param {Boolean} [reverse=false] enable reverse winding
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* @returns {Geometry|Feature<any>} rewind Geometry or Feature
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*/
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function rewindFeature(geojson, reverse) {
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var type = geojson.type === "Feature" ? geojson.geometry.type : geojson.type;
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// Support all GeoJSON Geometry Objects
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switch (type) {
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case "GeometryCollection":
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geomEach(geojson, function (geometry) {
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rewindFeature(geometry, reverse);
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});
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return geojson;
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case "LineString":
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rewindLineString(getCoords(geojson), reverse);
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return geojson;
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case "Polygon":
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rewindPolygon(getCoords(geojson), reverse);
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return geojson;
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case "MultiLineString":
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getCoords(geojson).forEach(function (lineCoords) {
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rewindLineString(lineCoords, reverse);
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});
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return geojson;
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case "MultiPolygon":
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getCoords(geojson).forEach(function (lineCoords) {
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rewindPolygon(lineCoords, reverse);
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});
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return geojson;
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case "Point":
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case "MultiPoint":
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return geojson;
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}
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}
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/**
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* Rewind LineString - outer ring clockwise
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*
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* @private
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* @param {Array<Array<number>>} coords GeoJSON LineString geometry coordinates
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* @param {Boolean} [reverse=false] enable reverse winding
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* @returns {void} mutates coordinates
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*/
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function rewindLineString(coords, reverse) {
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if (booleanClockwise(coords) === reverse) coords.reverse();
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}
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/**
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* Rewind Polygon - outer ring counterclockwise and inner rings clockwise.
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*
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* @private
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* @param {Array<Array<Array<number>>>} coords GeoJSON Polygon geometry coordinates
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* @param {Boolean} [reverse=false] enable reverse winding
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* @returns {void} mutates coordinates
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*/
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function rewindPolygon(coords, reverse) {
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// outer ring
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if (booleanClockwise(coords[0]) !== reverse) {
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coords[0].reverse();
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}
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// inner rings
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for (var i = 1; i < coords.length; i++) {
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if (booleanClockwise(coords[i]) === reverse) {
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coords[i].reverse();
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}
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}
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}
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export default rewind;
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