Drawing Tools

Sample code for Google Maps Platform JavaScript API author(s): Justin Poehnelt

HTML

<!DOCTYPE html>
<!--
 @license
 Copyright 2019 Google LLC. All Rights Reserved.
 SPDX-License-Identifier: Apache-2.0
-->
<html>
  <head>
    <title>Drawing Tools</title>
    <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script>
    <!-- jsFiddle will insert css and js -->
  </head>
  <body>
    <div id="map"></div>

    <!-- 
      The `defer` attribute causes the callback to execute after the full HTML
      document has been parsed. For non-blocking uses, avoiding race conditions,
      and consistent behavior across browsers, consider loading using Promises.
      See https://developers.google.com/maps/documentation/javascript/load-maps-js-api
      for more information.
      -->
    <script
      src="https://maps.googleapis.com/maps/api/js?key=AIzaSyB41DRUbKWJHPxaFjMAwdrzWzbVKartNGg&callback=initMap&libraries=drawing,geometry&v=weekly"
      defer
    ></script>
  </body>
</html>

CSS

/**
 * @license
 * Copyright 2019 Google LLC. All Rights Reserved.
 * SPDX-License-Identifier: Apache-2.0
 */
/* 
 * Always set the map height explicitly to define the size of the div element
 * that contains the map. 
 */
#map {
  height: 100%;
}

/* 
 * Optional: Makes the sample page fill the window. 
 */
html,
body {
  height: 100%;
  margin: 0;
  padding: 0;
}

JavaScript

/**
 * @license
 * Copyright 2019 Google LLC. All Rights Reserved.
 * SPDX-License-Identifier: Apache-2.0
 */
// This example requires the Drawing library. Include the libraries=drawing
// parameter when you first load the API. For example:
// <script src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&libraries=drawing">

let startLatLng;
let currentMovingPolyIndex = -1;

const polygonsInstance = [];

function initMap() {
  const map = new google.maps.Map(document.getElementById("map"), {
    center: {
      lat: -34.397,
      lng: 150.644
    },
    zoom: 18,
  });
  const drawingManager = new google.maps.drawing.DrawingManager({
    drawingMode: google.maps.drawing.OverlayType.POLYGON,
    drawingControl: true,
    drawingControlOptions: {
      position: google.maps.ControlPosition.TOP_CENTER,
      drawingModes: [
        google.maps.drawing.OverlayType.POLYGON,
      ],
    },
  });

  drawingManager.setMap(map);
  // ==================================================== //

  const onDrawingComplete = (polygon) => {
    polygon.setOptions({
      draggable: true,
      clickable: true
    });

    polygonsInstance.push(polygon);

    polygon.index = polygonsInstance.length - 1;

    polygon.addListener('dragstart', ({
      latLng
    }) => {
      currentMovingPolyIndex = polygon.index;
      startLatLng = latLng;
    })

    polygon.addListener('drag', ({
      latLng: endLatLng
    }) => {
      const heading = google.maps.geometry.spherical.computeHeading(startLatLng, endLatLng);
      const movedDistance = google.maps.geometry.spherical.computeDistanceBetween(startLatLng, endLatLng);

      polygonsInstance.forEach((polygonInst, index) => {
        if (currentMovingPolyIndex !== index) {
          const currentPath = polygonInst.getPath().getArray();
          const newPath = currentPath.map(path => {
            return google.maps.geometry.spherical.computeOffset(path, movedDistance, heading);
          });
         ...