44 lines
1.3 KiB
TypeScript
44 lines
1.3 KiB
TypeScript
/**
|
|
* Utilities for Intaleq Map SDK.
|
|
*/
|
|
export class PolylineUtils {
|
|
/**
|
|
* Decodes a Google-encoded polyline string into an array of [lng, lat] coordinates.
|
|
* Note: MapLibre and GeoJSON use [lng, lat] while Google/Flutter use [lat, lng].
|
|
*/
|
|
static decode(encoded: string): [number, number][] {
|
|
const points: [number, number][] = [];
|
|
let index = 0;
|
|
const len = encoded.length;
|
|
let lat = 0;
|
|
let lng = 0;
|
|
|
|
while (index < len) {
|
|
let b: number;
|
|
let shift = 0;
|
|
let result = 0;
|
|
do {
|
|
b = encoded.charCodeAt(index++) - 63;
|
|
result |= (b & 0x1f) << shift;
|
|
shift += 5;
|
|
} while (b >= 0x20);
|
|
const dlat = ((result & 1) !== 0 ? ~(result >> 1) : (result >> 1));
|
|
lat += dlat;
|
|
|
|
shift = 0;
|
|
result = 0;
|
|
do {
|
|
b = encoded.charCodeAt(index++) - 63;
|
|
result |= (b & 0x1f) << shift;
|
|
shift += 5;
|
|
} while (b >= 0x20);
|
|
const dlng = ((result & 1) !== 0 ? ~(result >> 1) : (result >> 1));
|
|
lng += dlng;
|
|
|
|
// MapLibre uses [lng, lat]
|
|
points.push([lng / 1E5, lat / 1E5]);
|
|
}
|
|
return points;
|
|
}
|
|
}
|