google-map-react/src/utils/lib_geo/transform.js

/* eslint-disable class-methods-use-this */
import Point from '@mapbox/point-geometry';
import LatLng from './lat_lng';
import { wrap } from './wrap';

// A single transform, generally used for a single tile to be scaled, rotated, and zoomed.
export default class Transform {
  constructor(tileSize, minZoom, maxZoom) {
    this.tileSize = tileSize || 512; // constant

    this._minZoom = minZoom || 0;
    this._maxZoom = maxZoom || 52;

    this.latRange = [-85.05113, 85.05113];

    this.width = 0;
    this.height = 0;
    this.zoom = 0;
    this.center = new LatLng(0, 0);
    this.angle = 0;
  }

  get minZoom() {
    return this._minZoom;
  }

  set minZoom(zoom) {
    this._minZoom = zoom;
    this.zoom = Math.max(this.zoom, zoom);
  }

  get maxZoom() {
    return this._maxZoom;
  }

  set maxZoom(zoom) {
    this._maxZoom = zoom;
    this.zoom = Math.min(this.zoom, zoom);
  }

  get worldSize() {
    return this.tileSize * this.scale;
  }

  get centerPoint() {
    return new Point(0, 0); // this.size._div(2);
  }

  get size() {
    return new Point(this.width, this.height);
  }

  get bearing() {
    return -this.angle / Math.PI * 180;
  }

  set bearing(bearing) {
    this.angle = -wrap(bearing, -180, 180) * Math.PI / 180;
  }

  get zoom() {
    return this._zoom;
  }

  set zoom(zoom) {
    const zoomV = Math.min(Math.max(zoom, this.minZoom), this.maxZoom);
    this._zoom = zoomV;
    this.scale = this.zoomScale(zoomV);
    this.tileZoom = Math.floor(zoomV);
    this.zoomFraction = zoomV - this.tileZoom;
  }

  zoomScale(zoom) {
    return Math.pow(2, zoom);
  }

  scaleZoom(scale) {
    return Math.log(scale) / Math.LN2;
  }

  project(latlng, worldSize) {
    return new Point(
      this.lngX(latlng.lng, worldSize),
      this.latY(latlng.lat, worldSize)
    );
  }

  unproject(point, worldSize) {
    return new LatLng(
      this.yLat(point.y, worldSize),
      this.xLng(point.x, worldSize)
    );
  }

  get x() {
    return this.lngX(this.center.lng);
  }

  get y() {
    return this.latY(this.center.lat);
  }

  get point() {
    return new Point(this.x, this.y);
  }

  // lat/lon <-> absolute pixel coords convertion
  lngX(lon, worldSize) {
    return (180 + lon) * (worldSize || this.worldSize) / 360;
  }

  // latitude to absolute y coord
  latY(lat, worldSize) {
    const y = 180 /
      Math.PI *
      Math.log(Math.tan(Math.PI / 4 + lat * Math.PI / 360));
    return (180 - y) * (worldSize || this.worldSize) / 360;
  }

  xLng(x, worldSize) {
    return x * 360 / (worldSize || this.worldSize) - 180;
  }

  yLat(y, worldSize) {
    const y2 = 180 - y * 360 / (worldSize || this.worldSize);
    return 360 / Math.PI * Math.atan(Math.exp(y2 * Math.PI / 180)) - 90;
  }

  locationPoint(latlng) {
    const p = this.project(latlng);
    return this.centerPoint._sub(this.point._sub(p)._rotate(this.angle));
  }

  pointLocation(p) {
    const p2 = this.centerPoint._sub(p)._rotate(-this.angle);
    return this.unproject(this.point.sub(p2));
  }
}