Mapping with Leaflet

Patrick Arlt

Experience Developer - Esri Portland R&D Center

@patrickarlt - http://bit.ly/1qmxndx

Who am I?

• Joined ESRI in 2012
• Came from a web design/startup background
• ArcGIS was something people asked me how to print from in college
• I didn't know what spatial references, projects, mercator or renderers were

How I approach the JS API

The JS API is a framework not a library

Frameworks vs Libraries

The JS API is a framework for building GIS apps

• Defines the what you can do and tells you how to do it
• Dojo is the framework, the JS API is the library
• API is overly complex and non-intuitive (for non-GIS)
• Difficult to seperate Dojo from the JS API

Leaflet

• Open source mapping library
• Focused on a small (33kb), extensible API
• Simple and clear API
• Huge plugin ecosystem

// create a map in the "map" div, set the view to a given lat/lng and zoom
var map = L.map('map').setView([ 33.8253818684, -116.5369606018], 16);

// add tiles from OpenStreetMap
L.tileLayer('http://{s}.tile.osm.org/{z}/{x}/{y}.png', {
    attribution: '© <a href="http://osm.org/copyright">OpenStreetMap</a>'
}).addTo(map);

// create a marker and add it to the map
var marker = new L.Marker([  33.82538186847268, -116.53696060180664]).addTo(map2);

// create a polygon and add it to the map
var polygon = new L.Polygon([[33.82667422214127, -116.53944969177246],[33.82485600863029, -116.53942823410033],[33.82476687952293, -116.54174566268921],[33.82325167048341, -116.54170274734497],[33.82325167048341, -116.537024974823],[33.8267098730001, -116.53708934783934],[33.82667422214127, -116.53944969177246]]).addTo(map2);

// bind a popup to our marker
marker.bindPopup("<p>Welome to Dev Summit!<p>");

// listen for click events on the polygon
polygon.on("click", function(e){
	alert("You clicked on the polygon at " + e.latlng);
});

Leaflet's API

• Simple - Uses Lat/Lng everywhere, no projections
• Literal - Obvious class and method names
• Consistent - Strict adherence to its own standards
• Fully Featured - Styling, Popups, Events
• Extendable - Classes, events, lots of utilities

Plugins!

So many plugins...

• Drawing https://github.com/Leaflet/Leaflet.draw
• Heatmaps https://github.com/Leaflet/Leaflet.heat
• Clustering https://github.com/Leaflet/Leaflet.markercluster
• Labeling https://github.com/Leaflet/Leaflet.label
• Data Formats https://github.com/mapbox/leaflet-omnivore
• And More ... http://leafletjs.com/plugins.html

Esri Leaflet

Leaflet plugins for ArcGIS

// create a map
var map = new L.Map("map").setView([ 33.8253818684, -116.5369606018], 12);

// add an ArcGIS Basemap
var tiles = L.esri.basemapLayer("Topographic").addTo(map);

// create a map
var map = L.map('map').setView([46.3, -60.7], 9);

// add a tile layer from ArcGIS Online or ArcGIS Server
var charts = new L.esri.TiledMapLayer("http://services.arcgisonline.com/ArcGIS/rest/services/Specialty/World_Navigation_Charts/MapServer").addTo(map);

var map = L.map('map').setView([36.272228, -116.817001], 7);

L.esri.basemapLayer("Gray").addTo(map);

var parks = new L.esri.DynamicMapLayer("http://mapservices.nps.gov/arcgis/rest/services/LandResourcesDivisionTractAndBoundaryService/MapServer").addTo(map);

L.esri.featureLayer("http://services.arcgis.com/rOo16HdIMeOBI4Mb/arcgis/rest/services/Portland_Parks/FeatureServer/0", {
	style: function (feature) {
	  return { color: "#70ca49", weight: 2 };
	},
  onEachFeature: function (feature, layer) {
    layer.bindPopup(feature.properties.NAME + "<br>" + feature.properties.ACRES + " Acres<br>Property ID "+feature.properties.PROPERTYID));
  }
}).addTo(map);

L.esri.clusteredFeatureLayer("http://services.arcgis.com/rOo16HdIMeOBI4Mb/arcgis/rest/services/stops/FeatureServer/0", {
	onEachMarker: function(feature, marker) {
    marker.bindPopup(feature.properties.stop_name+"<br>Stop ID: "+feature.properties.stop_id+"<br>"+feature.properties.stop_desc)
  }
}).addTo(map);

var heat = new L.esri.HeatMapFeatureLayer("http://services.arcgis.com/rOo16HdIMeOBI4Mb/arcgis/rest/services/Graffiti_Locations3/FeatureServer/0", {
  radius: 12
}).addTo(map);

var searchControl = new L.esri.Controls.Geosearch().addTo(map);

// listen for the results event and add every result to the map
searchControl.on("results", function(e){
	console.log(e.results);
});

var layer = L.esri.Demographics.demographicLayer('USAHealthCareSpending', {
    token: "A ArcGIS Online Token"
}).addTo(map);

Esri Leaflet

• Supports a wide variety of ArcGIS Services
• Clean Simple API
• Growing Fast
• Open Source

Smackdown!

Who Wins?

No One

Good developers choose the right tools for the project

Choose Esri Leaflet if you...

• are integrating into existing apps
• are already using Leaflet
• want a simpler focused toolset
• want to leverage non-ArcGIS Services or data
• want to leverage Leaflet Plugins

Choose the JS API if you...

• want a framework
• need deep integration with ArcGIS
• want to support everything (renderers, web maps…)
• work in non-web-mercator/wgs 84 projections
• love Dojo

You are my dev team

https://github.com/esri/esri-leaflet

https://github.com/Esri/esri-leaflet-geocoder

https://github.com/Esri/esri-leaflet-demographic-layer

API Roadmap

Thanks!

Twitter : @patrickarlt

Slides : http://bit.ly/1qmxndx