JSFiddle - React, Tailwind, and code Playground

by Lawrence Ross

HTML

<script src="https://maps.googleapis.com/maps/api/js?libraries=geometry,drawing"></script>
<title>Drawing Tools</title>
<div id="panel">
  <div id="color-palette"></div>
  <div>
    <button id="delete-button">Delete Selected Shape</button>
    <button id="calculate" onClick="calcar()">calculate area</button>
    <div id="area"></div>
  </div>
</div>
<div id="map"></div>

CSS

#map,
html,
body {
  padding: 0;
  margin: 0;
  height: 100%;
}

#panel {
  width: 200px;
  font-family: Arial, sans-serif;
  font-size: 13px;
  float: right;
  margin: 10px;
}

#color-palette {
  clear: both;
}

.color-button {
  width: 14px;
  height: 14px;
  font-size: 0;
  margin: 2px;
  float: left;
  cursor: pointer;
}

#delete-button {
  margin-top: 5px;
}

JavaScript

var drawingManager;
var selectedShape;
var colors = ['#1E90FF', '#FF1493', '#32CD32', '#FF8C00', '#4B0082'];
var selectedColor;
var colorButtons = {};

function clearSelection() {
  if (selectedShape) {
    selectedShape.setEditable(false);
    selectedShape = null;
  }
}

function setSelection(shape) {
  clearSelection();
  selectedShape = shape;
  shape.setEditable(true);
  selectColor(shape.get('fillColor') || shape.get('strokeColor'));
  google.maps.event.addListener(shape.getPath(), 'set_at', calcar);
  google.maps.event.addListener(shape.getPath(), 'insert_at', calcar);
}

function calcar() {
    var area = google.maps.geometry.spherical.computeArea(selectedShape.getPath());
    document.getElementById("area").innerHTML = "Area =" + area;
}

function deleteSelectedShape() {
  if (selectedShape) {
    selectedShape.setMap(null);
  }
}

function selectColor(color) {
  selectedColor = color;
  for (var i = 0; i < colors.length; ++i) {
    var currColor = colors[i];
    colorButtons[currColor].style.border = currColor == color ? '2px solid #789' : '2px solid #fff';
  }

  // Retrieves the current options from the drawing manager and replaces the
  // stroke or fill color as appropriate.
  var polylineOptions = drawingManager.get('polylineOptions');
  polylineOptions.strokeColor = color;
  drawingManager.set('polylineOptions', polylineOptions);

  var rectangleOptions = drawingManager.get('rectangleOptions');
  rectangleOptions.fillColor = color;
  drawingManager.set('rectangleOptions', rectangleOptions);

  var circleOptions = drawingManager.get('circleOptions');
  circleOptions.fillColor = color;
  drawingManager.set('circleOptions', circleOptions);

  var polygonOptions = drawingManager.get('polygonOptions');
  polygonOptions.fillColor = color;
  drawingManager.set('polygonOptions', polygonOptions);
}

function setSelectedShapeColor(color) {
  if (selectedShape) {
    if (selectedShape.type == google.maps.drawing.OverlayType.POLYLINE) {
     ...