@krozamdev/overlapping-marker-spiderfier
v0.2.8
Published
Deals with overlapping markers in the Leaflet maps API, Google Earth-style
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📦🤗 npm-friendly fork of jawj/OverlappingMarkerSpiderfier.
Overlapping Marker Spiderfier for Leaflet support ES6 Module
Ever noticed how, in Google Earth, marker pins that overlap each other spring apart gracefully when you click them, so you can pick the one you meant?
And ever noticed how, when using the Leaflet API, the same thing doesn't happen?
This code makes Leaflet map markers behave in that Google Earth way (minus the animation). Small numbers of markers (yes, up to 8) spiderfy into a circle. Larger numbers fan out into a more space-efficient spiral.
The compiled code has no dependencies beyond Leaflet. And it's under 3K when compiled out of CoffeeScript, minified with Google's Closure Compiler and gzipped.
It's a port of my original library for the Google Maps
API. (Since the
Leaflet API doesn't let us observe all the event types that the Google
one does, the main difference between the original and the port is this:
you must first call unspiderfy
if and when you want to move a marker
in the Leaflet version).
Doesn't clustering solve this problem?
You may have seen the marker clustering libraries, which also help deal with markers that are close together.
That might be what you want. However, it probably isn't what you want (or isn't the only thing you want) if you have markers that could be in the exact same location, or close enough to overlap even at the maximum zoom level. In that case, clustering won't help your users see and/or click on the marker they're looking for.
Demo
See the demo map (the data is random: reload the map to reposition the markers).
Download
Download the compiled, minified JS source.
Or download it from npm:
npm isntall -S @krozamdev/overlapping-marker-spiderfier
or
yarn add @krozamdev/overlapping-marker-spiderfier
How to use
See the demo map source, or follow along here for a slightly simpler usage with commentary.
Create your map like normal (using the beautiful Stamen watercolour OSM map):
var map = new L.Map('map_canvas', {center: new L.LatLng(51.505, -0.09), zoom: 13});
var layer = new L.StamenTileLayer('watercolor');
map.addLayer(layer);
Create an OverlappingMarkerSpiderfier
instance:
var oms = new OverlappingMarkerSpiderfier(map);
Instead of adding click listeners to your markers directly via
marker.addEventListener
or marker.on
, add a global listener on the
OverlappingMarkerSpiderfier
instance instead. The listener will be
passed the clicked marker as its first argument.
var popup = new L.Popup();
oms.addListener('click', function(marker) {
popup.setContent(marker.desc);
popup.setLatLng(marker.getLatLng());
map.openPopup(popup);
});
You can also add listeners on the spiderfy
and unspiderfy
events,
which will be passed an array of the markers affected. In this example,
we observe only the spiderfy
event, using it to close any open
InfoWindow
:
oms.addListener('spiderfy', function(markers) {
map.closePopup();
});
Finally, tell the OverlappingMarkerSpiderfier
instance about each
marker as you add it, using the addMarker
method:
for (var i = 0; i < window.mapData.length; i ++) {
var datum = window.mapData[i];
var loc = new L.LatLng(datum.lat, datum.lon);
var marker = new L.Marker(loc);
marker.desc = datum.d;
map.addLayer(marker);
oms.addMarker(marker); // <-- here
}
Docs
Loading
The Leaflet L
object must be available when this code runs --- i.e.
put the Leaflet API <script> tag before this one. The code has been
tested with the 0.4 API version.
Construction
new OverlappingMarkerSpiderfier(map, options)
Creates an instance associated with map
(an L.Map
).
The options
argument is an optional Object
specifying any options
you want changed from their defaults. The available options are:
keepSpiderfied (default: false
)
By default, the OverlappingMarkerSpiderfier works like Google Earth, in that when you click a spiderfied marker, the markers unspiderfy before any other action takes place.
Since this can make it tricky for the user to work through a set of
markers one by one, you can override this behaviour by setting the
keepSpiderfied
option to true
.
nearbyDistance (default: 20
).
This is the pixel radius within which a marker is considered to be overlapping a clicked marker.
circleSpiralSwitchover (default: 9
)
This is the lowest number of markers that will be fanned out into a
spiral instead of a circle. Set this to 0
to always get spirals, or
Infinity
for all circles.
legWeight (default: 1.5
)
This determines the thickness of the lines joining spiderfied markers to their original locations.
Instance methods: managing markers
Note: methods that have no obvious return value return the OverlappingMarkerSpiderfier instance they were called on, in case you want to chain method calls.
addMarker(marker)
Adds marker
(an L.Marker
) to be tracked.
removeMarker(marker)
Removes marker
from those being tracked.
clearMarkers()
Removes every marker
from being tracked. Much quicker than calling
removeMarker
in a loop, since that has to search the markers array
every time.
getMarkers()
Returns an Array
of all the markers that are currently being tracked.
This is a copy of the one used internally, so you can do what you like
with it.
Instance methods: managing listeners
addListener(event, listenerFunc)
Adds a listener to react to one of three events.
event
may be 'click'
, 'spiderfy'
or 'unspiderfy'
.
For 'click'
events, listenerFunc
receives one argument: the clicked
marker object. You'll probably want to use this listener to do something
like show an L.Popup
.
For 'spiderfy'
or 'unspiderfy'
events, listenerFunc
receives two
arguments: first, an Array
of the markers that were spiderfied or
unspiderfied; second, an Array
of the markers that were not. One use
for these listeners is to make some distinction between spiderfied and
non-spiderfied markers when some markers are spiderfied --- e.g.
highlighting those that are spiderfied, or dimming out those that
aren't.
removeListener(event, listenerFunc)
Removes the specified listener on the specified event.
clearListeners(event)
Removes all listeners on the specified event.
unspiderfy()
Returns any spiderfied markers to their original positions, and triggers
any listeners you may have set for this event. Unless no markers are
spiderfied, in which case it does nothing. Be sure to call this before
you call setLatLng
on any tracked marker.
Properties
You can set the following properties on an OverlappingMarkerSpiderfier instance:
legColors.usual and legColors.highlighted
These determine the usual and highlighted colours of the lines.
You can also get and set any of the options noted in the constructor function documentation above as properties on an OverlappingMarkerSpiderfier instance.
Licence
This software is released under the MIT licence.