Angular2 - How to setup a google.maps.OverlayView?

问题:

I'd like to create a google map component that work like that : https://jsfiddle.net/gvvy5vxz/2/

It's based on this : https://developers.google.com/maps/documentation/javascript/examples/overlay-simple

I'm new to typescript and i'm stuck with the prototype implementation, specially with this JS snippet:

USGSOverlay.prototype = new google.maps.OverlayView();

USGSOverlay(bounds, image, map) {

    // Initialize all properties.
    this.bounds_ = bounds;
    this.image_ = image;
    this.map_ = map;

    // Define a property to hold the image's div. We'll
    // actually create this div upon receipt of the onAdd()
    // method so we'll leave it null for now.
    this.div_ = null;

    // Explicitly call setMap on this overlay.
    this.setMap(map);
  }

I have no clue how to translate that in a typescript way and how to declare things properly.

I guess I should create a class USGSOverlay that extends google.maps.OverlayView but it doesn't work.

class USGSOverlay extends google.maps.OverlayView{

  bounds_;
  image_;
  map_;
  div_;

  constructor(bounds, image, map){
    // Initialize all properties.
    this.bounds_ = bounds;
    this.image_ = image;
    this.map_ = map;

    // Define a property to hold the image's div. We'll
    // actually create this div upon receipt of the onAdd()
    // method so we'll leave it null for now.
    this.div_ = null;

    // Explicitly call setMap on this overlay.
    this.setMap(map);
  }
}

This my working base component. It creates a simple map inside #map:

import { Component } from '@angular/core';
declare const google: any;
/*
/*  Component Map
*/
@Component({
  selector: 'map',
  template: `
    <div id="map"></div>
  `,
  styles: [
    `#map{ width:100%; height:100%; position: absolute; width:100%; height:100%; top:0; left:0;}`
  ],
})
export class MapComponent {

  ngOnInit(){
    google.maps.event.addDomListener(window, 'load', this.initMap);
  }

  initMap() {

    const map = new google.maps.Map(document.getElementById('map'), {
      zoom: 11,
      center: {lat: 62.323907, lng: -150.109291},
      mapTypeId: google.maps.MapTypeId.SATELLITE
    });

    const bounds = new google.maps.LatLngBounds(
        new google.maps.LatLng(62.281819, -150.287132),
        new google.maps.LatLng(62.400471, -150.005608));
  }
}

回答1:

Here is what worked for me (using ionic 2):

1. Use these commands:

   npm install typings --global
   typings install dt~google.maps --global --save
   typings install google.maps --global
   

2. Add "typings/*.d.ts" in your tsconfig.json:

   "include": [
     "src/**/*.ts",
     "typings/*.d.ts"
   ]
   

3. Here is the TypeScript code:

   import { Component, ViewChild, ElementRef } from '@angular/core';
   import { NavController } from 'ionic-angular';
   // import typings
   import { } from '@types/googlemaps';
   /*
   /*  Component Map
   */
   @Component({
       selector: 'page-overlay',
       templateUrl: 'overlay.html'
   })
   export class OverlayPage {
       @ViewChild('map') mapElement: ElementRef;
       map: any;
       // weird syntax, I know, but it works
       constructor(public navCtrl: NavController) {
       }
       USGSOverlay = class extends google.maps.OverlayView {
           bounds_: any;
           image_: any;
           map_: any;
           div_: any;
           constructor(bounds, image, private map) {
               super();
               // Initialize all properties.
               this.bounds_ = bounds;
               this.image_ = image;
               this.map_ = map;
               // Define a property to hold the image's div. We'll
               // actually create this div upon receipt of the onAdd()
               // method so we'll leave it null for now.
               this.div_ = null;
               // Explicitly call setMap on this overlay.
               this.setMap(map);
               this.set
           }
           /**
            * onAdd is called when the map's panes are ready and the overlay has been
            * added to the map.
            */
           onAdd() {
               const div = document.createElement('div');
               div.style.borderStyle = 'none';
               div.style.borderWidth = '0px';
               div.style.position = 'absolute';
               // Create the img element and attach it to the div.
               const img = document.createElement('img');
               img.src = this.image_;
               img.style.width = '100%';
               img.style.height = '100%';
               img.style.position = 'absolute';
               div.appendChild(img);
               this.div_ = div;
               // Add the element to the "overlayLayer" pane.
               const panes = this.getPanes();
               panes.overlayLayer.appendChild(div);
           };
           draw() {
               // We use the south-west and north-east
               // coordinates of the overlay to peg it to the correct position and size.
               // To do this, we need to retrieve the projection from the overlay.
               const overlayProjection = this.getProjection();
               // Retrieve the south-west and north-east coordinates of this overlay
               // in LatLngs and convert them to pixel coordinates.
               // We'll use these coordinates to resize the div.
               const sw = overlayProjection.fromLatLngToDivPixel(this.bounds_.getSouthWest());
               const ne = overlayProjection.fromLatLngToDivPixel(this.bounds_.getNorthEast());
               // Resize the image's div to fit the indicated dimensions.
               const div = this.div_;
               div.style.left = sw.x + 'px';
               div.style.top = ne.y + 'px';
               div.style.width = (ne.x - sw.x) + 'px';
               div.style.height = (sw.y - ne.y) + 'px';
           };
           // The onRemove() method will be called automatically from the API if
           // we ever set the overlay's map property to 'null'.
           onRemove() {
               this.div_.parentNode.removeChild(this.div_);
               this.div_ = null;
           };
       };
       ngOnInit() {
           this.loadMap();
           var bounds = new google.maps.LatLngBounds(
               new google.maps.LatLng(62.281819, -150.287132),
               new google.maps.LatLng(62.400471, -150.005608));
           // The photograph is courtesy of the U.S. Geological Survey.
           var srcImage = 'https://developers.google.com/maps/documentation/' +
               'javascript/examples/full/images/talkeetna.png';
           const overlay = new this.USGSOverlay(bounds, srcImage, this.map);
           //overlay.setMap(this.map);
       }
       ionViewDidLoad() {
           this.loadMap();
           var bounds = new google.maps.LatLngBounds(
               new google.maps.LatLng(62.281819, -150.287132),
               new google.maps.LatLng(62.400471, -150.005608));
           // The photograph is courtesy of the U.S. Geological Survey.
           var srcImage = 'https://developers.google.com/maps/documentation/' +
               'javascript/examples/full/images/talkeetna.png';
           const overlay = new this.USGSOverlay(bounds, srcImage, this.map);
           //overlay.setMap(this.map);
       }
       loadMap() {        
           let latLng = new google.maps.LatLng(62.323907, -150.109291);
           var mapOptions = {
               zoom :15,
               center : latLng,
               enableHighAccuracy: true,
               timeout: 5000,
               maximumAge: 0
           };
           this.map = new google.maps.Map(this.mapElement.nativeElement, mapOptions);
       }
   }
   

回答2:

I was on the good way it works...

import { Component } from '@angular/core';
declare const google: any;

class USGSOverlay extends google.maps.OverlayView{

  bounds_;
  image_;
  map_;
  div_;

  constructor(bounds, image, map){
    // Initialize all properties.
    this.bounds_ = bounds;
    this.image_ = image;
    this.map_ = map;

    // Define a property to hold the image's div. We'll
    // actually create this div upon receipt of the onAdd()
    // method so we'll leave it null for now.
    this.div_ = null;

    // Explicitly call setMap on this overlay.
    this.setMap(map);
  }

  /**
   * onAdd is called when the map's panes are ready and the overlay has been
   * added to the map.
   */
  onAdd(){
    const div = document.createElement('div');
    div.style.borderStyle = 'none';
    div.style.borderWidth = '0px';
    div.style.position = 'absolute';

    // Create the img element and attach it to the div.
    const img = document.createElement('img');
    img.src = this.image_;
    img.style.width = '100%';
    img.style.height = '100%';
    img.style.position = 'absolute';
    div.appendChild(img);

    this.div_ = div;

    // Add the element to the "overlayLayer" pane.
    const panes = this.getPanes();
    panes.overlayLayer.appendChild(div);
  };

  draw(){

    // We use the south-west and north-east
    // coordinates of the overlay to peg it to the correct position and size.
    // To do this, we need to retrieve the projection from the overlay.
    const overlayProjection = this.getProjection();

    // Retrieve the south-west and north-east coordinates of this overlay
    // in LatLngs and convert them to pixel coordinates.
    // We'll use these coordinates to resize the div.
    const sw = overlayProjection.fromLatLngToDivPixel(this.bounds_.getSouthWest());
    const ne = overlayProjection.fromLatLngToDivPixel(this.bounds_.getNorthEast());

    // Resize the image's div to fit the indicated dimensions.
    const div = this.div_;
    div.style.left = sw.x + 'px';
    div.style.top = ne.y + 'px';
    div.style.width = (ne.x - sw.x) + 'px';
    div.style.height = (sw.y - ne.y) + 'px';
  };

  // The onRemove() method will be called automatically from the API if
  // we ever set the overlay's map property to 'null'.
  onRemove(){
    this.div_.parentNode.removeChild(this.div_);
    this.div_ = null;
  };
};



/*
/*  Component Map
*/
@Component({
  selector: 'map',
  template: `
    <div id="map"></div>
  `,
  styles: [
    `#map{ width:100%; height:100%; position: absolute; width:100%; height:100%; top:0; left:0;}`
  ],
})
export class MapComponent {

  overlay;

  ngOnInit(){
    google.maps.event.addDomListener(window, 'load', this.initMap);
  }

  initMap() {

    const map = new google.maps.Map(document.getElementById('map'), {
      zoom: 11,
      center: {lat: 62.323907, lng: -150.109291},
      mapTypeId: google.maps.MapTypeId.SATELLITE
    });

    const bounds = new google.maps.LatLngBounds(
        new google.maps.LatLng(62.281819, -150.287132),
        new google.maps.LatLng(62.400471, -150.005608));

    // The photograph is courtesy of the U.S. Geological Survey.
    const srcImage = 'https://developers.google.com/maps/documentation/' +
        'javascript/examples/full/images/talkeetna.png';

    // The custom USGSOverlay object contains the USGS image,
    // the bounds of the image, and a reference to the map.
    this.overlay = new USGSOverlay(bounds, srcImage, map);
  }
}

回答3:

I also had loads of trouble with this but eventually came right. It's vital that the google maps script is pre-loaded (I loaded mine in my route resolver) otherwise you'll get a 'google' is not defined error. See here on how I installed typings and imported the library.

As for the syntax, I ended up using an inner class for this. This is because, if it's a top-level class WebPack attempts (unsuccessfully) to find the google maps library at compile time:

// import typings
import {} from '@types/googlemaps';

@Component({...})
export class MapComponent implements OnInit {
  // weird syntax, I know, but it works
  USGSOverlay = class extends google.maps.OverlayView {
    constructor(bounds, image, private map){
      super();
      ...
      this.setMap(this.map);
    }
    onAdd(){...}
    draw(){...}
  }
  ngOnInit() {
    const overlay = new this.Overlay(bounds, image, map);
  }
}

回答4:

As my code loads google maps API asynchronously, the above answers did not work for me. My problem was typescript use google variable before loaded google API.

Here is a solution I found.

To see async map loader code, see Load Google Maps JS API in component [Angular]

service

//map.service.ts

import { Injectable } from '@angular/core';

...
declare var google;    
export let MyOverlay; // declare and use this from other ts file

@Injectable({ providedIn: 'root' })
export class MapService {

    private static promise;
    map: any;

    public static load() {
        if (!MapService.promise) {
            MapService.promise = new Promise((resolve) => {
              //load google api asynchronously
            });
        }

        return MapService.promise;
    }

    async initMap(gmapElement, lat = -33.92, lng = 151.25) {
        return MapService.load()  
            .then((gapi) => {
                //map init
                this.map = new google.maps.Map(gmapElement.nativeElement, {
                   //map options
                })
                /*** before init MyOverlay, 
                1. Google API should be loaded
                2. AFTER MAP init(rendering), Overlay Object has Projection to calculate Overlay location
                ***/
                this.initMyOverlay()
            })
            .catch(console.log)
    }

    initMyOverlay(){            
        class MyOverlayCls extends google.maps.OverlayView {    
         //omitted for code readability
        }
        MyOverlay = MyOverlayCls ; //assign class to variable
    }

}

component

//map.component.ts
import { MapService, MyOverlay} from 'map.service';
...

  @ViewChild('gmap') gmapElement: any
  ...

  ngOnInit() {
    console.log("maps init")
    this.mapSvc.initMap(this.gmapElement).then(_ => {

      //At this time, google API has been loaded and assigned MyOverlay as MyOverlayCls
      let overlay= new MyOverlay(...)    

    })

回答5:

In my case, i can not have an inner-class in the same class responsible for loading map. It took me sometime to figure out how to do it. This is how i did it

export class mapTextOverlayService {

  //Overlay is creatd in an inner-class because if it is at top-level class google maps library may not be available at the class load time
  mapTextOverlay = class extends google.maps.OverlayView {

    pos_;
    text_;
    map_;
    div_;

    constructor(pos, text, map) {
      super();
      // Initialize all properties.
      this.pos_ = pos;
      this.text_ = text;
      this.map_ = map;

      // Define a property to hold the text's div. We'll
      // actually create this div upon receipt of the onAdd()
      // method so we'll leave it null for now.
      this.div_ = null;

      // Explicitly call setMap on this overlay.
      this.setMap(map);
    }

    /**
     * onAdd is called when the map's panes are ready and the overlay has been
     * added to the map.
     */
    onAdd() {
      const div = document.createElement('div');
      div.style.borderStyle = 'none';
      div.style.borderWidth = '0px';
      div.style.position = 'absolute';

      div.innerHTML = this.text_;

      this.div_ = div;

      // Add the element to the "overlayLayer" pane.
      const panes = this.getPanes();
      panes.overlayLayer.appendChild(div);
    };

    draw() {
      // We are using bounds centre to peg it to the correct position.
      // To do this, we need to retrieve the projection from the overlay.
      const overlayProjection = this.getProjection();

      // Convert the centre coordinates of this overlay from LatLngs to pixel coordinates.
      // We'll use these coordinates to provide the dimensions of div.
      const pixelPos = overlayProjection.fromLatLngToDivPixel(this.pos_);

      const div = this.div_;
      div.style.left = pixelPos.x + 'px';
      div.style.top = pixelPos.y + 'px';
    };

    // The onRemove() method will be called automatically from the API if
    // we ever set the overlay's map property to 'null'.
    onRemove() {
      this.div_.parentNode.removeChild(this.div_);
      this.div_ = null;
    };

    onHide() {
      if (this.div_) {
        this.div_.style.visibility = 'hidden';
      } 
    };

  }

  createMapTextOverlay(pos, text, map) {
    return new this.mapTextOverlay(pos, text, map);
  }

};

And then in the component where i want to create a text overlay:

let mtos = new mapTextOverlayService();
let label = mtos.createMapTextOverlay(boundsCenter, description, this.map.mapobject);