Custom Controls

Shows how to create custom controls.

This example creates a "rotate to north" button.

main.js

import 'ol/ol.css';
import Map from 'ol/Map';
import OSM from 'ol/source/OSM';
import TileLayer from 'ol/layer/Tile';
import View from 'ol/View';
import {Control, defaults as defaultControls} from 'ol/control';

//
// Define rotate to north control.
//

class RotateNorthControl extends Control {
  /**
   * @param {Object} [opt_options] Control options.
   */
  constructor(opt_options) {
    const options = opt_options || {};

    const button = document.createElement('button');
    button.innerHTML = 'N';

    const element = document.createElement('div');
    element.className = 'rotate-north ol-unselectable ol-control';
    element.appendChild(button);

    super({
      element: element,
      target: options.target,
    });

    button.addEventListener('click', this.handleRotateNorth.bind(this), false);
  }

  handleRotateNorth() {
    this.getMap().getView().setRotation(0);
  }
}

//
// Create map, giving it a rotate to north control.
//

const map = new Map({
  controls: defaultControls().extend([new RotateNorthControl()]),
  layers: [
    new TileLayer({
      source: new OSM(),
    }),
  ],
  target: 'map',
  view: new View({
    center: [0, 0],
    zoom: 3,
    rotation: 1,
  }),
});

index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>Custom Controls</title>
    <!-- Pointer events polyfill for old browsers, see https://caniuse.com/#feat=pointer -->
    <script src="https://unpkg.com/elm-pep@1.0.6/dist/elm-pep.js"></script>
    <!-- The lines below are only needed for old environments like Internet Explorer and Android 4.x -->
    <script src="https://cdn.polyfill.io/v3/polyfill.min.js?features=fetch,requestAnimationFrame,Element.prototype.classList,TextDecoder"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/core-js/3.18.3/minified.js"></script>
    <style>
      .map {
        width: 100%;
        height:400px;
      }
      .rotate-north {
        top: 65px;
        left: .5em;
      }
      .ol-touch .rotate-north {
        top: 80px;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <script src="main.js"></script>
  </body>
</html>

package.json

{
  "name": "custom-controls",
  "dependencies": {
    "ol": "6.13.1-dev"
  },
  "devDependencies": {
    "parcel": "^2.0.0"
  },
  "scripts": {
    "start": "parcel index.html",
    "build": "parcel build --public-url . index.html"
  }
}