terriajs/dist/Core/GeoJson.js

Geospatial data visualization platform.

import { feature, featureCollection } from "@turf/helpers";
import { isJsonObject, isJsonString } from "./Json";
// Note: these type checks are not that rigorous, we are assuming we are getting valid GeoJson objects
export function isFeatureCollection(json) {
    return (isJsonObject(json, false) &&
        json.type === "FeatureCollection" &&
        Array.isArray(json.features));
}
export function isFeature(json) {
    return (isJsonObject(json, false) && json.type === "Feature" && !!json.geometry);
}
export function isPoint(json) {
    return (isJsonObject(json, false) &&
        json.type === "Feature" &&
        isJsonObject(json.geometry, false) &&
        json.geometry.type === "Point");
}
export function isMultiPoint(json) {
    return (isJsonObject(json, false) &&
        json.type === "Feature" &&
        isJsonObject(json.geometry, false) &&
        json.geometry.type === "MultiPoint");
}
export function isLine(json) {
    return (isJsonObject(json, false) &&
        json.type === "Feature" &&
        isJsonObject(json.geometry, false) &&
        json.geometry.type === "LineString");
}
export function isMultiLineString(json) {
    return (isJsonObject(json, false) &&
        json.type === "Feature" &&
        isJsonObject(json.geometry, false) &&
        json.geometry.type === "MultiLineString");
}
export function isPolygon(json) {
    return (isJsonObject(json, false) &&
        json.type === "Feature" &&
        isJsonObject(json.geometry, false) &&
        json.geometry.type === "Polygon");
}
export function isMultiPolygon(json) {
    return (isJsonObject(json, false) &&
        json.type === "Feature" &&
        isJsonObject(json.geometry, false) &&
        json.geometry.type === "MultiPolygon");
}
export function isGeometryCollection(json) {
    return (isJsonObject(json, false) &&
        json.type === "Feature" &&
        isJsonObject(json.geometry, false) &&
        json.geometry.type === "GeometryCollection");
}
export function isGeometries(json) {
    return (isJsonObject(json, false) &&
        isJsonString(json.type) &&
        [
            "Point",
            "MultiPoint",
            "LineString",
            "MultiLineString",
            "Polygon",
            "MultiPolygon"
        ].includes(json.type) &&
        Array.isArray(json.coordinates));
}
/**
 * Returns the points in a MultiPoint as separate Point features.
 */
export function explodeMultiPoint(feature) {
    return feature.geometry?.type === "MultiPoint"
        ? feature.geometry.coordinates.map((coordinates) => ({
            type: "Feature",
            geometry: {
                type: "Point",
                coordinates
            },
            properties: feature.properties
        }))
        : [];
}
export function toFeatureCollection(json) {
    if (isFeatureCollection(json))
        return json; // It's already a feature collection, do nothing
    if (isFeature(json)) {
        // Move CRS data from Feature to FeatureCollection
        if ("crs" in json && isJsonObject(json.crs)) {
            const crs = json.crs;
            delete json.crs;
            const fc = featureCollection([json]);
            fc.crs = crs;
            return fc;
        }
        return featureCollection([json]);
    }
    if (isGeometries(json))
        return featureCollection([feature(json)]);
    if (Array.isArray(json) && json.every((item) => isFeature(item))) {
        return featureCollection(json);
    }
    if (Array.isArray(json) && json.every((item) => isGeometries(item))) {
        return featureCollection(json.map((item) => feature(item)));
    }
}
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