Open-source mobile-friendly maps

about me



Ryan Ohs



Phoenix Web Group
Waverly, Nebraska






var map = L.map('map').setView([51.505, -0.09], 13);

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

L.marker([51.5, -0.09]).addTo(map)
    .bindPopup('A pretty CSS3 popup. 
Easily customizable.')     .openPopup();

why leaflet?


  • Google Maps for Business costs $10,000/yr
  • Easy to use API
  • Lightweight
    • 64K (vs 700K for OpenLayers)
  • Desktop and mobile support
  • Retina display support with high-dpi tiles
  • Currently at version 0.7.2
    • Started in 2010
    • Over 3000 commits and 157 contributers

what is openstreetmap?


  • Wikipedia for maps
  • Data has open license
  • User editable
  • 1.5 million editors (doubling every year)
  • > 2 trillion data points

OSM vs Google





Getting map tiles for free

  • OpenStreetMap

  • MapQuest Open license
    • Free, open license, requires attribution
    • For heavy usage (>4000 tiles/sec), contact them first
    • JPEG

  • MapBox
    • Free tier
    • No satellite imagery

Commercial Options



  • CloudMade
    • Original creator of Leaflet
    • $30 per 1 million tiles

  • MapBox     (Lead dev now works here)
    • Free, then starting at $5/mo
      • Roughly $30 per 900,000 tiles
    • Also supports making your own tiles and layers

  • Big list at http://wiki.openstreetmap.org/wiki/Commercial_OSM_Software_and_Services

Tiles and zooming


http://{s}.tile.osm.org/{z}/{x}/{y}.png

  • 20 zoom levels
    • 0 = whole world
    • 13 = a town
    • 19 = 1 ft/px
    • Each level is about double the previous
  • Tiles are 256 x 256px PNG images
  • Approximately 15 tiles in a “map view”

getting started

  1. Link to javascript and stylesheet
    <link rel="stylesheet" href="http://cdn.leafletjs.com/leaflet-0.7.2/leaflet.css" />
    <script src="http://cdn.leafletjs.com/leaflet-0.7.2/leaflet.js"></script>
  2. Add a map div. Give it a height.
    <div id="map" style="height: 600px"></div>
  3. Initialize the map.
    var map = L.map('map').setView([51.505, -0.09], 13);
  4. Add a map tile layer
    L.tileLayer('http://{s}.tile.osm.org/{z}/{x}/{y}.png', {
        attribution: '© <a href="http://osm.org/copyright">
    OpenStreetMap</a> contributors'
    }).addTo(map);

mobile setup

Full screen support
body {
    padding: 0;
    margin: 0;
}
html, body, #map {
    height: 100%;
}
Disable automatic scaling
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no" />
Initialize map (no coordinates here)
 var map = L.map('map');

L.tileLayer('map url', {
    attribution: 'attribution line',
    maxZoom: 18
}).addTo(map);

Geolocation

Zoom to the user's current position
 map.locate({setView: true, maxZoom: 16});
Continue initialization after success
function onLocationFound(e) {
    var radius = e.accuracy / 2;
    L.marker(e.latlng).addTo(map)
        .bindPopup("You are within " + radius + " meters from this point").openPopup();
    L.circle(e.latlng, radius).addTo(map);
}

map.on('locationfound', onLocationFound);
Handle error or permission denied
 function onLocationError(e) {
    alert(e.message);
}

map.on('locationerror', onLocationError);

Markers

Consist of an image and a shadow

 var appleIcon = L.icon({
    iconUrl: "../lib/images/apple.png",
    shadowUrl: "../lib/images/square-shadow.png",
    iconSize:     [32, 37],
    shadowSize:   [51, 37],
    iconAnchor:   [16, 37],
    shadowAnchor: [17, 37],
    popupAnchor:  [0, -37]
});
 
L.marker([51.5, -0.09], {icon: appleIcon}).addTo(map);

Creating Markers


Lots of free icons available online

Maps Icon Collection (CC BY SA 3.0)


Custom icons need custom shadow shapes

MArker Anchors

 iconSize:     [32, 37],
 shadowSize:   [51, 37],
 iconAnchor:   [16, 37],
 shadowAnchor: [17, 37],
 popupAnchor:  [0, -37]

Popups

Popups can be bound to a coordinate, marker, or shape.
marker.bindPopup("<b>Hello world!</b><br>I am a popup.").openPopup();
L.popup()
 .setLatLng([51.5, -0.09])
 .setContent("I am a standalone popup.")
 .openOn(map);

Shapes


  • Circles
  • Polygons
  • Lines
  • Paths

var circle = L.circle([51.508, -0.11], 500, {
    color: 'red',
    fillColor: '#f03',
    fillOpacity: 0.5
}).addTo(map);

var polygon = L.polygon([
    [51.509, -0.08],
    [51.503, -0.06],
    [51.51, -0.047]
]).addTo(map);

Layers

Two types:
  1. Base layers - only one can be visible
  2. Overlays - markers, geoJSON, etc.

Add default layers to the map initialization:
 var map = L.map('map', {
    center: new L.LatLng(40.82,-96.65),
    zoom: 10,
    layers: [streets, cities]
}); 

Add a Layers Control object to the map:
 L.control.layers(baseMaps, overlayMaps).addTo(map);

        var littleton = L.marker([39.61, -105.02]).bindPopup('This is Littleton, CO.'),
    denver    = L.marker([39.74, -104.99]).bindPopup('This is Denver, CO.'),
    aurora    = L.marker([39.73, -104.8]).bindPopup('This is Aurora, CO.'),
    golden    = L.marker([39.77, -105.23]).bindPopup('This is Golden, CO.');
var cities = L.layerGroup([littleton, denver, aurora, golden]);

var url = 'https://{s}.tiles.mapbox.com/v3/{key}/{z}/{x}/{y}.png';
var attribution = 'MapBox';

var streets   = L.tileLayer(url, {key: "rohs.hkme15d0", attribution: attribution});
var terrain  = L.tileLayer(url, {key: "rohs.hkmf3lfh",   attribution: attribution});

var map = L.map('map', {
    center: new L.LatLng(39.7308819,-105.0348376),
    zoom: 9,
    layers: [streets, cities]
});

var baseMaps = {
	"Streets" : streets,
	"Terrain" : terrain
};

var overlayMaps = {
	"Cities": cities
};

L.control.layers(baseMaps, overlayMaps).addTo(map);
    

GEOJSON

Programmatically defining map elements is verbose.
GeoJSON is a standard format.

Using GEOJSON


Attach styles to geoJSON shapes:
var myStyle = {
    "color": "red",
    "weight": 5,
    "opacity": 0.65
};

L.geoJson(myLines, { 
        style: myStyle
    }).addTo(map);

Points are converted to markers.
Alternatively you can turn them into a shape.

 var geojsonMarkerOptions = {
    radius: 8,
    fillColor: "#ff7800",
    color: "#000",
    weight: 1,
    opacity: 1,
    fillOpacity: 0.8
};

L.geoJson(someGeojsonFeature, {
    pointToLayer: function (feature, latlng) {
        return L.circleMarker(latlng, geojsonMarkerOptions);
    }
}).addTo(map);


You can attach popups to geoJSON features.


 function onEachFeature(feature, layer) {
    if (feature.properties && feature.properties.popupContent) {
        layer.bindPopup(feature.properties.popupContent);
    }
}

L.geoJson(geojsonFeature, {
    onEachFeature: onEachFeature
}).addTo(map);



You can filter geoJSON datasets.

L.geoJson(someFeatures, {
    filter: function(feature, layer) {
        return feature.properties.show_on_map;
    }
}).addTo(map);

Making geojson



MapBox TileMill - native app

Online editor at http://geojson.io/

MongoDB can serve and query geoJSON

routes


MapQuest routing plugin
 var map = L.map('map', {
    layers: MQ.mapLayer(),
    center: [ 38.895345, -77.030101 ],
    zoom: 15
});
 
var dir = MQ.routing.directions();
 
dir.route({
    locations: [
        '1600 pennsylvania ave, washington dc',
        '935 pennsylvania ave, washington dc'
    ]
});
 
map.addLayer(MQ.routing.routeLayer({ directions: dir, fitBounds: true }));

event model


  • click
  • mouseover object
  • dragging
  • popups
  • resize
  • geolocation
  • errors

Events Demo


LeafLET.Draw

Marker cluster plugin


PLUGINS


Labels
BounceMarker
KML
geoCSV
Heatmap
Terminator
Context menu

data visualization


RESOURCES


leaflet online


Find this Presentation





All code examples will be at




questions?

leaflet.js

By rohs

leaflet.js

Nebraska Code Camp 2014; The embedded code samples are available at https://gist.github.com/ryanohs/9810195

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