OpenLayers

vs

Leaflet

What are Openlayers & Leaflet?

  • Open source Javascript libraries used to build web mapping applications
  • Supports most mobile and desktop platforms, supporting HTML5 and CSS3
  • 2-clause FreeBSD license

Map data

Map server

JS library

Browser

  • Released in June 2006 by MetaCarta Labs
  • Latest stable release 3.10.1  (October 9, 2015)
  • Used by ~12,000 websites around the world*
  • Released in May 2011 by Vladimir Agafonkin
  • Latest stable release 0.7.7 (October 26, 2015)
  • Used by ~32,000 websites around the world*

About & Statistics

*SimilarTech

An opensource javascript library to load, display and render maps from multiple sources on web pages

An Open-Source JavaScript Library for Mobile-Friendly Interactive Maps

*SimilarTech

*SimilarTech

Comparisons

Javascript

Size of minified JS file

 

Number of classes/namespaces

 

Unminified file

465.3 KB

 

163

 

3.5 MB*

126.5 KB

 

52

 

223.6 KB

*due to dependency to Closure Library

  • A lot of built in stuff
  • Very few plugins
  • Very few built in stuff
  • A lot of plugins

Example

Require plugins

Leaflet.Omnivore (data formats)
Leaflet.draw
Leaflet.markercluster
Leaflet.MapboxVectorTile

Built-in

Library & Plugins

General Concept

  • A wrapper over HTML elements
     

  • L.GridLayer is a grid of <div>s or <canvas>s or <img>s

  • A model of "classic" GIS

     
  • ol.Feature has a ol.geom which can be a ol.geom.LinearRing or ol.geom.MultiPoint or any Simple Features Specification type

Coding Patterns

Basic Map Display

<!DOCTYPE html>
<html>
  <head>
    <title>Simple Openlayers Map</title>
    <link rel="stylesheet" href="http://openlayers.org/en/v3.12.1/css/ol.css" type="text/css">
    <script src="http://openlayers.org/en/v3.12.1/build/ol.js"></script>
  </head>
  <body>
    <div id="map" class="map"></div>
    <script>
      var map = new ol.Map({
  	layers: [
    	new ol.layer.Tile({
      	source: new ol.source.OSM() })
  	],
  		target: 'map',
  		view: new ol.View({
		projection: ol.proj.get('EPSG:4326'),
    		center: [101.4603,2.9588],
    		zoom: 10})
	});
    </script>
  </body>
</html>
<!DOCTYPE html>
<html>
  <head>
    <title>Simple Leaflet Map</title>
    <link rel="stylesheet" href="http://cdn.leafletjs.com/leaflet-0.7/leaflet.css"/>
    <script src="http://cdn.leafletjs.com/leaflet-0.7/leaflet.js"></script>
  </head>
  <body>
    <div id="map" style="width: 600px; height: 400px"></div>
    <script>
        var map = L.map('map').setView([2.9588,101.4603], 10);
        mapLink = '<a href="http://openstreetmap.org">OpenStreetMap</a>';
        L.tileLayer(
            'http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
            attribution: 'Map data © ' + mapLink,
            maxZoom: 18,
            }).addTo(map);
    </script>
  </body>
</html>

Basic Map Display

var map = new ol.Map({
layers: [
new ol.layer.Tile({
  source: new ol.source.OSM() })
  ],
      target: 'map',
      view: new ol.View({
      projection: ol.proj.get('EPSG:4326'),
      center: [101.4603,2.9588],
      zoom: 10})
});
var map = L.map('map').setView([2.9588,101.4603], 10);
mapLink = '<a href="http://openstreetmap.org">OpenStreetMap</a>';
L.tileLayer(
    'http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
    attribution: 'Map data © ' + mapLink,
    maxZoom: 18,
}).addTo(map);

class constructors style

object factories style

Add a Simple Marker

var iconFeature = new ol.Feature({
    geometry: new ol.geom.Point([101.4603,2.9588]),
});

var iconStyle = new ol.style.Style({
    image: new ol.style.Icon( ({
    src: 'http://dev.openlayers.org/releases/OpenLayers-2.13.1/examples/img/mobile-loc.png'
    }))
});

iconFeature.setStyle(iconStyle);
var vectorSource = new ol.source.Vector({
    features: [iconFeature]
});

var vectorLayer = new ol.layer.Vector({
    source: vectorSource
});
	  
var map = new ol.Map({
    layers: [
    new ol.layer.Tile({
    source: new ol.source.OSM() }),
	vectorLayer
	],
  	target: 'map',
  	view: new ol.View({
	projection: ol.proj.get('EPSG:4326'),
    	center: [101.4603,2.9588],
    	zoom: 10})
});
var map = L.map('map').setView([2.9588,101.4603], 10);
mapLink = '<a href="http://openstreetmap.org">OpenStreetMap</a>';

L.tileLayer(
     'http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
     attribution: 'Map data © ' + mapLink,
     maxZoom: 18,
}).addTo(map);

var marker = L.marker([2.9588,101.4603])
    .addTo(map);
  • No control for styling/labeling
  • But can be achieved using various plugins
  • More control over styling
  • But need to understand feature/classes and how it works

Add a popup to marker

// create icon feature
// 2 lines of codes

// define style for icon
// 3 lines of codes
// set icon style

// create popup div element for popup
// 10 lines of codes
// define style for popup
// 5-10 lines of codes
// define popup behavior (show, hide, close etc)
// 10-15 lines of codes

// bind popup to icon
// 3 lines of codes

// create and set vector layer for icon
// 4 lines of codes
	  
var map = new ol.Map({
    layers: [
    new ol.layer.Tile({
    source: new ol.source.OSM() }),
	vectorLayer
	],
  	target: 'map',
  	view: new ol.View({
	projection: ol.proj.get('EPSG:4326'),
    	center: [101.4603,2.9588],
    	zoom: 10})
});
var map = L.map('map').setView([2.9588,101.4603], 10);
mapLink = '<a href="http://openstreetmap.org">OpenStreetMap</a>';

L.tileLayer(
     'http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
     attribution: 'Map data © ' + mapLink,
     maxZoom: 18,
}).addTo(map);

var marker = L.marker([2.9588,101.4603])
    .addTo(map)
    .bindPopup("<b>Hello!</b><br>I am a popup!")
    .openPopup();

Documentations

  • Concise API reference
  • Manually maintained HTML
    • Not consistent
    • Easily out of sync
  • 5 examples (official)
  • Verbose API reference
  • Auto-generated JSDoc
    • Consistent
    • Always sync
       
  • 125+ examples (official)

How to decide?

  • Simple map display application
    • various plugins to provide pretty UI
    • easy to understand coding pattern
  • Lightweight application for mobile apps
    • only compile required plugins
  • Customized & complex GIS web application
    • low level API access
    • better support for OGC standards
    • GIS layer/geom model
  • Require integration with various map formats or projections
    • native support for CSV, KML & WKT - easy to handle interaction between map functions
    • native support for reprojection

Trivia

  • TMOM still use OpenLayers 2.X
  • Leaflet doesn't support Mapguide 2.X tiled maps
    • No Leaflet plugins yet
    • Using Mapguide WMS will be too slow
    • OpenLayers 3.X complete redesign of the mapping library, including removal of native support for Mapguide & use of Canvas renderer making it unable to work in IE8
  • TMOM Web Mobile starts using OL3

Quiz

Customer requests assistance to display Smartmap API on their website with marker pointing location of their stores. Which map library should be sufficient to fulfill the requirement?

Question 1

The new TMOM Mobile would like to implement similar feedback function like TMOM Web which allow users to draw point, line or polygon on a desired area. Which map library should be sufficient to fulfill the requirements?

Question 2

OL vs L

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