import {GeoOperations} from "./GeoOperations"; import {UIElement} from "../UI/UIElement"; import Combine from "../UI/Base/Combine"; import State from "../State"; export class ExtraFunction { static readonly intro = `

Calculating tags with Javascript

In some cases, it is useful to have some tags calculated based on other properties. Some useful tags are available by default (e.g. lat, lon, _country), as detailed above.

It is also possible to calculate your own tags - but this requires some javascript knowledge.

Before proceeding, some warnings: In the layer object, add a field calculatedTags, e.g.:
"calculatedTags": [ "_someKey=javascript-expression", "name=feat.properties.name ?? feat.properties.ref ?? feat.properties.operator", "_distanceCloserThen3Km=feat.distanceTo( some_lon, some_lat) < 3 ? 'yes' : 'no'" ]
The above code will be executed for every feature in the layer. The feature is accessible as feat and is an amended geojson object: - area contains the surface area (in square meters) of the object - lat and lon contain the latitude and longitude Some advanced functions are available on feat as well: ` private static readonly OverlapFunc = new ExtraFunction( "overlapWith", "Gives a list of features from the specified layer which this feature overlaps with, the amount of overlap in m². The returned value is { feat: GeoJSONFeature, overlap: number}", ["...layerIds - one or more layer ids of the layer from which every feature is checked for overlap)"], (featuresPerLayer, feat) => { return (...layerIds: string[]) => { const result = [] for (const layerId of layerIds) { const otherLayer = featuresPerLayer.get(layerId); if (otherLayer === undefined) { continue; } if (otherLayer.length === 0) { continue; } result.push(...GeoOperations.calculateOverlap(feat, otherLayer)); } return result; } } ) private static readonly DistanceToFunc = new ExtraFunction( "distanceTo", "Calculates the distance between the feature and a specified point", ["longitude", "latitude"], (featuresPerLayer, feature) => { return (arg0, lat) => { if (typeof arg0 === "number") { const lon = arg0 // Feature._lon and ._lat is conveniently place by one of the other metatags return GeoOperations.distanceBetween([lon, lat], [feature._lon, feature._lat]); } else { // arg0 is probably a feature return GeoOperations.distanceBetween(GeoOperations.centerpointCoordinates(arg0), [feature._lon, feature._lat]) } } } ) private static readonly ClosestObjectFunc = new ExtraFunction( "closest", "Given either a list of geojson features or a single layer name, gives the single object which is nearest to the feature. In the case of ways/polygons, only the centerpoint is considered.", ["list of features"], (featuresPerLayer, feature) => { return (features) => { if (typeof features === "string") { features = featuresPerLayer.get(features) } let closestFeature = undefined; let closestDistance = undefined; for (const otherFeature of features) { if (otherFeature == feature) { continue; // We ignore self } let distance = undefined; if (otherFeature._lon !== undefined && otherFeature._lat !== undefined) { distance = GeoOperations.distanceBetween([otherFeature._lon, otherFeature._lat], [feature._lon, feature._lat]); } else { distance = GeoOperations.distanceBetween( GeoOperations.centerpointCoordinates(otherFeature), [feature._lon, feature._lat] ) } if (distance === undefined) { throw "Undefined distance!" } if (closestFeature === undefined || distance < closestDistance) { closestFeature = otherFeature closestDistance = distance; } } return closestFeature; } } ) private static readonly Memberships = new ExtraFunction( "memberships", "Gives a list of {role: string, relation: Relation}-objects, containing all the relations that this feature is part of. \n\nFor example: `_part_of_walking_routes=feat.memberships().map(r => r.relation.tags.name).join(';')`", [], (featuresPerLayer, feature) => { return () => { return State.state.knownRelations.data?.get(feature.id) ?? []; } } ) private static readonly allFuncs: ExtraFunction[] = [ExtraFunction.DistanceToFunc, ExtraFunction.OverlapFunc, ExtraFunction.ClosestObjectFunc, ExtraFunction.Memberships]; private readonly _name: string; private readonly _args: string[]; private readonly _doc: string; private readonly _f: (featuresPerLayer: Map, feat: any) => any; constructor(name: string, doc: string, args: string[], f: ((featuresPerLayer: Map, feat: any) => any)) { this._name = name; this._doc = doc; this._args = args; this._f = f; } public static FullPatchFeature(featuresPerLayer: Map, feature) { for (const func of ExtraFunction.allFuncs) { func.PatchFeature(featuresPerLayer, feature); } } public static HelpText(): UIElement { return new Combine([ ExtraFunction.intro, "
    ", ...ExtraFunction.allFuncs.map(func => new Combine([ "
  • ", func._name, "
  • " ]) ), "
", ...ExtraFunction.allFuncs.map(func => new Combine([ "

" + func._name + "

", func._doc, "
    ", ...func._args.map(arg => "
  • " + arg + "
  • "), "
" ]) ) ]); } public PatchFeature(featuresPerLayer: Map, feature: any) { feature[this._name] = this._f(featuresPerLayer, feature); } }