mapcomplete/Logic/MetaTagging.ts
2021-03-24 02:01:04 +01:00

166 lines
5.4 KiB
TypeScript

import {GeoOperations} from "./GeoOperations";
import LayerConfig from "../Customizations/JSON/LayerConfig";
import SimpleMetaTagger from "./SimpleMetaTagger";
import {UIElement} from "../UI/UIElement";
import Combine from "../UI/Base/Combine";
export class ExtraFunction {
static readonly intro = `<h2>Calculating tags with Javascript</h2>
<p>In some cases, it is useful to have some tags calculated based on other properties. Some useful tags are available by default (e.g. <b>_lat</b>, <b>lon</b>, <b>_country</b>), as detailed above.</p>
<p>It is also possible to calculate your own tags - but this requires some javascript knowledge. </p>
Before proceeding, some warnings:
<ul>
<li> DO NOT DO THIS AS BEGINNER</li>
<li> <b>Only do this if all other techniques fail</b>. This should <i>not</i> be done to create a rendering effect, only to calculate a specific value</li>
<li> <b>THIS MIGHT BE DISABLED WITHOUT ANY NOTICE ON UNOFFICIAL THEMES</b>. As unofficial themes might be loaded from the internet, this is the equivalent of injecting arbitrary code into the client. It'll be disabled if abuse occurs.</li>
</ul>
In the layer object, add a field <b>calculatedTags</b>, e.g.:
<div class="code">
"calculatedTags": {
"_someKey": "javascript-expression",
"name": "feat.properties.name ?? feat.properties.ref ?? feat.properties.operator",
"_distanceCloserThen3Km": "feat.distanceTo( some_lon, some_lat) < 3 ? 'yes' : 'no'"
}
</div>
`
private static DistanceToFunc = new ExtraFunction(
"distanceTo",
"Calculates the distance between the feature and a specified point",
["longitude", "latitude"],
(feature) => {
return (lon, lat) => {
// Feature._lon and ._lat is conveniently place by one of the other metatags
return GeoOperations.distanceBetween([lon, lat], [feature._lon, feature._lat]);
}
}
)
private static readonly allFuncs: ExtraFunction[] = [ExtraFunction.DistanceToFunc];
private readonly _name: string;
private readonly _args: string[];
private readonly _doc: string;
private readonly _f: (feat: any) => any;
constructor(name: string, doc: string, args: string[], f: ((feat: any) => any)) {
this._name = name;
this._doc = doc;
this._args = args;
this._f = f;
}
public static FullPatchFeature(feature) {
for (const func of ExtraFunction.allFuncs) {
func.PatchFeature(feature);
}
}
public static HelpText(): UIElement {
return new Combine([
ExtraFunction.intro,
...ExtraFunction.allFuncs.map(func =>
new Combine([
"<h3>" + func._name + "</h3>",
func._doc,
"<ul>",
...func._args.map(arg => "<li>" + arg + "</li>"),
"</ul>"
])
)
]);
}
public PatchFeature(feature: any) {
feature[this._name] = this._f(feature);
}
}
/**
* Metatagging adds various tags to the elements, e.g. lat, lon, surface area, ...
*
* All metatags start with an underscore
*/
export default class MetaTagging {
/**
* An actor which adds metatags on every feature in the given object
* The features are a list of geojson-features, with a "properties"-field and geometry
*/
static addMetatags(features: { feature: any; freshness: Date }[], layers: LayerConfig[]) {
for (const metatag of SimpleMetaTagger.metatags) {
try {
metatag.addMetaTags(features);
} catch (e) {
console.error("Could not calculate metatag for ", metatag.keys.join(","), ":", e)
}
}
// The functions - per layer - which add the new keys
const layerFuncs = new Map<string, ((feature: any) => void)>();
for (const layer of layers) {
layerFuncs.set(layer.id, this.createRetaggingFunc(layer));
}
for (const feature of features) {
// @ts-ignore
const key = feature.feature._matching_layer_id;
const f = layerFuncs.get(key);
if (f === undefined) {
continue;
}
f(feature.feature)
}
}
private static createRetaggingFunc(layer: LayerConfig): ((feature: any) => void) {
const calculatedTags: [string, string][] = layer.calculatedTags;
if (calculatedTags === undefined) {
return undefined;
}
const functions: ((feature: any) => void)[] = [];
for (const entry of calculatedTags) {
const key = entry[0]
const code = entry[1];
if (code === undefined) {
continue;
}
const func = new Function("feat", "return " + code + ";");
const f = (feature: any) => {
feature.properties[key] = func(feature);
}
functions.push(f)
}
return (feature) => {
const tags = feature.properties
if (tags === undefined) {
return;
}
ExtraFunction.FullPatchFeature(feature);
for (const f of functions) {
try {
f(feature);
} catch (e) {
console.error("While calculating a tag value: ", e)
}
}
}
}
}