maplibre-gl/src/util/smart_wrap.test.ts

BSD licensed community fork of mapbox-gl, a WebGL interactive maps library

import {describe, test, expect} from 'vitest';
import Point from '@mapbox/point-geometry';
import {LngLat} from '../geo/lng_lat';
import {smartWrap} from './smart_wrap';
import {MercatorTransform} from '../geo/projection/mercator_transform';

const transform = new MercatorTransform();
transform.resize(100, 100);
transform.isPointOnMapSurface = (p) => p.y > transform.height / 2; // any point below map center is considered to be on the map's surface

describe('smartWrap', () => {
    test('Shifts lng to -360 deg when such point is closer to the priorPos', () => {
        transform.locationToScreenPoint = ((ll: LngLat) => {
            if (ll.lng === -360) {
                return new Point(90, 51); // close to priorPos & below horizon
            } else {
                return new Point(120, 51);
            }
        });

        const result = smartWrap(
            new LngLat(0, 0),
            new Point(100, 51),
            transform);
        expect(result.lng).toBe(-360);
    });

    test('Shifts lng to +360 deg when such point is closer to the priorPos', () => {
        transform.locationToScreenPoint = ((ll: LngLat) => {
            if (ll.lng === 360) {
                return new Point(90, 51); // close to priorPos & below horizon
            } else {
                return new Point(120, 51);
            }
        });

        const result = smartWrap(
            new LngLat(0, 0),
            new Point(100, 51),
            transform);
        expect(result.lng).toBe(360);
    });

    test('Does not change lng when there are no closer points at -360 and +360 deg', () => {
        transform.locationToScreenPoint = ((ll: LngLat) => {
            if (ll.lng === 15) {
                return new Point(90, 51); // close to priorPos & below horizon
            } else {
                return new Point(12000, 51);
            }
        });

        const result = smartWrap(
            new LngLat(15, 0),
            new Point(100, 51),
            transform);
        expect(result.lng).toBe(15);
    });

    test('Does not change lng to -360 deg when such point is above horizon', () => {
        transform.locationToScreenPoint = ((ll: LngLat) => {
            if (ll.lng === -360) {
                return new Point(90, 49); // close to priorPos BUT above horizon
            } else {
                return new Point(120, 51);
            }
        });

        const result = smartWrap(
            new LngLat(0, 0),
            new Point(100, 51),
            transform);
        expect(result.lng).toBe(0);
    });

    test('Shifts lng to -360 if lng is outside viewport on the right and at least 180° from map center', () => {
        transform.center.lng = 50;
        transform.locationToScreenPoint = (() => { return new Point(110, 51); }); // outside viewport

        const result = smartWrap(
            new LngLat(250, 0), // 200 from map center
            new Point(0, 0), // priorPos doesn't matter in this case
            transform);
        expect(result.lng).toBe(-110);
    });

    test('Shifts lng to +360 if lng is outside viewport on the left and at least 180° from map center', () => {
        transform.center.lng = 50;
        transform.locationToScreenPoint = (() => { return new Point(-10, 51); }); // outside viewport

        const result = smartWrap(
            new LngLat(-150, 0), // 200 from map center
            new Point(0, 0), // priorPos doesn't matter in this case
            transform);
        expect(result.lng).toBe(210);
    });
});