Google Maps Markers

shape Introduction

The chapter demonstrates about the Google Maps Markers and following are the topics covered.

  • Markers

shape Description

To identify the location on a map, markers are used in Google Maps. By default, the Google Maps JavaScript API uses a standard images as markers.

Google provides the custom icon options to users, so that a custom icon can be created with in the constructor called markers or by calling setIcon() on marker.

Adding a marker

shape Description

A marker can be created using the google.maps.Marker constructor. The following are the main things to be remembered before creating a marker.

shape Example

The example below demonstrate the main scheme of adding a marker in Google Maps.

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="initial-scale=1.0, user-scalable=no">
<meta charset="utf-8">
<title>Simple markers</title>
<style>
html, body {
height: 100%;
margin: 0;
padding: 0;
}
#map {
height: 100%;
}
</style>
</head>
<body>
<div id="map"></div>
<script>
function initMap() {
var myLatLng = {lat: 17.3700, lng: 78.4800};
var map = new google.maps.Map(document.getElementById('map'), {
zoom: 6,
center: myLatLng
});
var marker = new google.maps.Marker({
position: myLatLng,
map: map,
});
}
</script>
<script async defer
src="https://maps.googleapis.com/maps/api/js?key=&signed_in=true&callback=initMap"></script>
</body>
</html>

Remove a marker

shape Description

Using setMap() method marker can be removed on the map by passing the argument as null .
Marker.setamap(null); method only removes the marker on the map, if user wish to delete the marker should set null to the marker itself.
A set of markers can be managed by creating arrays. This arrays are helpful to remove a particular marker in a group of markers by calling the setMap() method.

shape Example

The below example demonstrate hiding and deleting a marker in Google Maps JavaScript applications.

<!DOCTYPE html>
<html>
  <head>
    <title>Removeing a Markers</title>
    <style>
      html, body {
        height: 100%;
        margin: 0;
        padding: 0;
      }
      #map {
        height: 100%;
      }
#floating-panel {
  position: absolute;
  top: 10px;
  left: 25%;
  z-index: 5;
  background-color: #010101;
  padding: 10px;
  border: 1px solid #BCB7B7;
  text-align: center;
  font-family: 'Roboto','sans-serif';
  line-height: 30px;
  padding-left: 10px;
}
    </style>
  </head>
  <body>
    <div id="floating-panel">
      <input onclick="clearMarkers();" type=button value="Hide Markers">
      <input onclick="showMarkers();" type=button value="Show All Markers">
      <input onclick="deleteMarkers();" type=button value="Delete Markers">
    </div>
    <div id="map"></div>
    <p>Click on the map to add markers.</p>
    <script>

// When the user clicks on the map, the markers get appeared.
// The markers are stored in an array.
// User can click an option to hide, show or delete the markers.
var map;
var markers = [];

function initMap() {
  var haightAshbury = {lat: 28.6139, lng:  77.2090};
  map = new google.maps.Map(document.getElementById('map'), {
    zoom: 5,
    center: haightAshbury,
    mapTypeId: google.maps.MapTypeId.TERRAIN
  });

  // This event listener will call addMarker() when the map is clicked.
  map.addListener('click', function(event) {
    addMarker(event.latLng);
  });
  // Adds a marker at the center of the map.
  addMarker(haightAshbury);
}

// Adds a marker to the map and push to the array.
function addMarker(location) {
  var marker = new google.maps.Marker({
    position: location,
    map: map
  });
  markers.push(marker);
}
// Sets the map on all markers in the array.
function setMapOnAll(map) {
  for (var i = 0; i < markers.length; i++) {
    markers[i].setMap(map);
  }
}
// Removes the markers from the map, but keeps them in the array.
function clearMarkers() {
  setMapOnAll(null);
}
// Shows any markers currently in the array.
function showMarkers() {
  setMapOnAll(map);
}
// Deletes all markers in the array by removing references to them.
function deleteMarkers() {
  clearMarkers();
  markers = [];
}
    </script>
    <script async defer
        src="https://maps.googleapis.com/maps/api/js?key=&signed_in=true&callback=initMap"></script>
  </body>
</html>

Animation Marker

shape Description

Markers can be animated by using google.maps.animation in Google Maps API. The following animations are supported by Google Map API.

shape Example 1

Example below demonstrate the marker bouncing and droping animation property in Google Maps JavaScript API.

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>Marker Animations</title>
    <style>
      html, body {
        height: 100%;
        margin: 0;
        padding: 0;
      }
      #map {
        height: 100%;
      }
    </style>
  </head>
  <body>
    <div id="map"></div>
    <script>
var marker;
function initMap() {
  var map = new google.maps.Map(document.getElementById('map'), {
    zoom: 10,
    center: {lat: 17.3700, lng: 78.4800}
  });
  marker = new google.maps.Marker({
    map: map,
    draggable: true,
    animation: google.maps.Animation.DROP,
    position: {lat: 17.3700, lng: 78.4800}
  });
  marker.addListener('click', toggleBounce);
}
function toggleBounce() {
  if (marker.getAnimation() !== null) {
    marker.setAnimation(null);
  } else {
    marker.setAnimation(google.maps.Animation.BOUNCE);
  }
}

shape Example 2

The below example demonstrate creating animation property for a group of markers. by using the setTimeout() to space the animations of the markers.

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>Marker animations with <code>setTimeout()</code></title>
    <style>
      html, body {
        height: 100%;
        margin: 0;
        padding: 0;
      }
      #map {
        height: 100%;
      }
#floating-panel {
  position: absolute;
  top: 10px;
  left: 40%;
  z-index: 5;
  background-color: #010101;
  padding: 5px;
  border: 2px solid #BCB7B7;
  text-align: center;
  font-family: 'Roboto','sans-serif';
  line-height: 30px;
  padding-left: 10px;
}
      #floating-panel {
        margin-left: -52px;
      }
    </style>
  </head>
  <body>
    <div id="floating-panel">
      <button id="drop" onclick="drop()">Drop Markers</button>
     </div>
    <div id="map"></div>
    <script>

// If user weant to adding a number of markers and want to drop them on the map
// window.setTimeout() used to space your markers' animation.

var neighborhoods = [
  {lat: 28.6139, lng: 77.2090},
  {lat: 18.9750, lng: 72.8258},
  {lat: 13.0827, lng: 80.2707},
  {lat: 12.9667, lng: 77.5667},
  {lat: 17.3700, lng: 78.4800}
];
var markers = [];
var map;
function initMap() {
  map = new google.maps.Map(document.getElementById('map'), {
    zoom: 5,
    center: {lat: 21.0000, lng: 78.0000}
  });
}
function drop() {
  clearMarkers();
  for (var i = 0; i < neighborhoods.length; i++) {
    addMarkerWithTimeout(neighborhoods[i], i * 200);
  }
}
function addMarkerWithTimeout(position, timeout) {
  window.setTimeout(function() {
    markers.push(new google.maps.Marker({
      position: position,
      map: map,
      animation: google.maps.Animation.DROP
    }));
  }, timeout);
}
function clearMarkers() {
  for (var i = 0; i < markers.length; i++) {
    markers[i].setMap(null);
  }
  markers = [];
}
    </script>
    <script async defer
        src="https://maps.googleapis.com/maps/api/js?key=&signed_in=true&callback=initMap"></script>
  </body>
</html>

Summary

shape Key points

  • Objects on the maps depends on Latitude and Longitude, so when the user zoom or drag on the map the objects moves.
  • Standard images are used as Markers by Google Maps.

shape Programming
Tips

  • Copy the API key obtained from Google Maps API and paste using the JavaScript tag in the code for loading Maps.
  • Set the required Map Properties for better output.
  • Make sure the latitude and longitudes of the required location mentioned to be correct.