如何在Angular应用程序组件中使用Typescript类方法

Question

I'm totally new to Angular 5 and typescript. I want to use this JS code in my Angular component ( http://jsbin.com/rorecuce/1/edit?html,output ) So, I try to convert it into a typescript class like this(Sorry, I don't know whether it's correct or not, If someone please check and correct me )

    class MercatorProjection {
  TILE_SIZE = 256;
  pixelOrigin_ : any;
  pixelsPerLonDegree_: any;
  pixelsPerLonRadian_: any;

  bound(value, opt_min, opt_max) {
    if (opt_min !== null) value = Math.max(value, opt_min);
    if (opt_max !== null) value = Math.min(value, opt_max);
    return value;
  }

  degreesToRadians(deg) {
    return deg * (Math.PI / 180);
  }

  radiansToDegrees(rad) {
    return rad / (Math.PI / 180);
  }

  MercatorProjection() {
    let pixelOrigin_ = new google.maps.Point(this.TILE_SIZE / 2, this.TILE_SIZE / 2);
    var pixelsPerLonDegree_ = this.TILE_SIZE / 360;
    var pixelsPerLonRadian_ = this.TILE_SIZE / (2 * Math.PI);
  }

  public fromLatLngToPoint(latLng,
    opt_point) {

      var point = opt_point || new google.maps.Point(0, 0);
      var origin = this.pixelOrigin_;

      point.x = origin.x + latLng.lng() * this.pixelsPerLonDegree_;

      var siny = this.bound(Math.sin(this.degreesToRadians(latLng.lat())), - 0.9999,
      0.9999);
      point.y = origin.y + 0.5 * Math.log((1 + siny) / (1 - siny)) * - this.pixelsPerLonRadian_;
      return point;
  }

  public fromPointToLatLng(point) {

    var origin = this.pixelOrigin_;
    var lng = (point.x - origin.x) / this.pixelsPerLonDegree_;
    var latRadians = (point.y - origin.y) / -this.pixelsPerLonRadian_;
    var lat = this.radiansToDegrees(2 * Math.atan(Math.exp(latRadians)) - Math.PI / 2);
    return new google.maps.LatLng(lat, lng);
  }
}

Inside my app.component.ts , I have a method as getNewRadius(), I want to access above methods. This is what I tried.

getNewRadius(){
  var numTiles = 1 << this.map.getZoom()
  var center =this.map.getCenter();
  var moved = google.maps.geometry.spherical.computeOffset(center, 10000, 90); /*1000 meters to the right*/
  var projection = new MercatorProjection;
  var initCoord = MercatorProjection.fromLatLngToPoint(center);
  var endCoord = MercatorProjection.fromLatLngToPoint(moved);
  var initPoint = new google.maps.Point(
    initCoord.x * numTiles,
    initCoord.y * numTiles);
   var endPoint = new google.maps.Point(
    endCoord.x * numTiles,
    endCoord.y * numTiles);
  var pixelsPerMeter = (Math.abs(initPoint.x-endPoint.x))/10000.0;
  var totalPixelSize = Math.floor(this.desiredRadiusPerPointInMeters*pixelsPerMeter);
  console.log(totalPixelSize);
  return totalPixelSize;

}

But I'm getting error [ts] Property 'fromLatLngToPoint' does not exist on type 'typeof MercatorProjection'.

Answer 1

Your method needs 2 parameters

 public fromLatLngToPoint(latLng, opt_point) ...

And you are calling it with only one

var initCoord = MercatorProjection.fromLatLngToPoint(center);
var endCoord = MercatorProjection.fromLatLngToPoint(moved);

Try with this

Call it with 2 params

var emptyPoint = new google.maps.Point(0, 0);
var initCoord = MercatorProjection.fromLatLngToPoint(center, emptyPoint);
var endCoord = MercatorProjection.fromLatLngToPoint(moved, emptyPoint);

And declare your method static as you are calling it from the class

public static fromLatLngToPoint(latLng,opt_point) { ...