Leaflet.MarkerCluster.LayerSupport

Sub-plugin for Leaflet.markercluster plugin (MCG in short); brings compatibility with L.Control.Layers and other Leaflet plugins. I.e. everything that uses direct calls to map.addLayer and map.removeLayer.

Leaflet.markercluster plugin provides beautiful animated Marker Clustering functionality.

Leaflet is the leading open-source JavaScript library for mobile-friendly interactive maps.

Size: 6 kB minified, < 2 kB gzipped.

NOTE: if your usage requires only compatibility of MCG with L.Control.Layers, you might be interested in this more simple plugin: Leaflet.FeatureGroup.SubGroup.

Requirements

• Requires Leaflet 1.x.x
• Leaflet.markercluster plugin, version 1.0.0+
• For Leaflet 0.7.x use the v0.1.0 release or the leaflet-0.7 branch

Demos

• LayerSupport with standard L.Control.Layers
• LayerSupport with LeafletSlider plugin

Usage instructions

Quick Guide

HTML:

<!-- After Leaflet and Leaflet.markercluster scripts -->
<script src="leaflet.markercluster.layersupport.js"></script>

JavaScript:

var map = L.map("map"),
    mcgLayerSupportGroup = L.markerClusterGroup.layerSupport(options),
    myLayerGroup = L.layerGroup(arrayOfMarkers);
    
mcgLayerSupportGroup.addTo(map);
mcgLayerSupportGroup.checkIn(myLayerGroup); // <= this is where the magic happens!

myLayerGroup.addTo(map);

Now adding the Layer Group to the map adds clustered markers!

Works also with individual markers, so this means it should virtually be compatible with any plugin that adds to / removes markers from map (e.g. LeafletSlider).

Installing the sub-plugin

Local copy

1. Download the "leaflet.markercluster.layersupport.js" file from the v2.0.1 release.
2. Place the file alongside your page.
3. Add the script tag (see Quick Guide > HTML) to your page after Leaflet and Leaflet.markercluster scripts.

CDN

You can alternatively use the free unpkg CDN service, but keep in mind that it "is a free, best-effort service and cannot provide any uptime or support guarantees".

<!-- After Leaflet and Leaflet.markercluster scripts -->
<script src="https://unpkg.com/leaflet.markercluster.layersupport@2.0.1/dist/leaflet.markercluster.layersupport.js"></script>

npm

1. Add this package to your project:

   $ npm install leaflet.markercluster.layersupport --save

2. If you are using a bundling tool, import in your JavaScript. It only performs the side effect of attaching to the global L namespace, so you do not need to store it into a local variable or import a namespace.

   require('leaflet.markercluster.layersupport');
   // Or with ES6:
   import 'leaflet.markercluster.layersupport';

Creation

Simply use the L.markerClusterGroup.layerSupport factory instead of your regular L.markerClusterGroup:

var mcgLayerSupportGroup = L.markerClusterGroup.layerSupport(options);

mcgLayerSupportGroup.addTo(map);

Do not forget to add it to your map.

Adding and removing Markers / Layer Groups

Use the regular MCG methods (like addLayer, addLayers, etc.) to add Markers and/or Layer Groups to the MCG Layer Support group and to show them on to the map at the same time.

Layer Support provides 2 new methods checkIn and checkOut that do the same but do not show right away the passed Markers and/or Layer Groups on to the map. They accept a single layer or an array of layers.

Adding will automatically check in.

Check out will automatically remove from map.

Dynamically add to and remove from map while clustering

Once Markers and/or Layer Groups are added (or checked in) to the MCG Layer Support group, you can then directly add and remove them from the map; all child Markers will be added to or removed from the group, as if you had called group.addLayer (or group.removeLayer) instead.

This means that other Leaflet plugins (including standard Layers Control) that dynamically add to or remove markers from the map are now compatible with the clustering functionality!

For example, you can now gather Markers into several Layer Groups and use them as Overlays in L.Control.Layers: when ticking / un-ticking the Overlay name in the Control, markers will automatically cluster / be removed.

API Reference

Options

Option	Type	Default	Description
singleAddRemoveBufferDuration	Number	0	Gathers all calls to addLayer and removeLayer single operations (on this MCG) that happen during the specified duration (in ms) for batch processing. Similar to throttling with execution on trailing edge only. Use 0 to disable throttling. Disabled by default (see #11)

Methods

Method	Returns	Description
checkIn( <ILayer> or <ILayer[]> layers )	this	Stamps the given Marker(s) or Layer Group(s) so that whenever they are added to or removed from the map later on, they are added to or removed from this group instead. If they are already on a map when checkIn is called, but they do not belong to this group yet, they are removed from that map.
checkOut( <ILayer> or <ILayer[]> layers )	this	Un-Stamps the given Marker(s) or Layer Group(s) so that they retrieve their normal behaviour. Also removes the layers from the map.

MCG Layer Support does not provide any extra event.

Regular MCG options, events and methods

All regular MCG options, events and methods are available within MCG Layer Support. Refer to Leaflet.markercluster documentation.

Method	Returns	Description
addLayer and addLayers	this	Check in all passed layers, besides the normal behaviour.
removeLayer and removeLayers	this	Normal behaviour only. They do not check out layers.

Limitations

No clustering before at least one MCG Layer Support group has been added to map

As long as no MCG Layer Support group has been added to a given map, the latter will not be able to redirect calls to addLayer to the appropriate Layer Support group, even if you have properly checked in all Markers and Layer Groups. They will appear on the map without clustering. Once you add an MCG Layer Support group, it will collect its layers and re-add them properly clustered.

After that, markers already added on map will be collected by their respective Layer Support group once the latter are added to the map.

Later additions of checked in markers to the map will not show anything as long as the Layer Support group they belong to is not on map. If it is on map, then they show up normally (clustered).

Checked in Layer Group with child checked out marker

Refrain from doing the following: check in a Layer Group into an MCG Layer Support group (this checks in all child markers of that group) then check out one or several of the child markers individually.

The result is simple: when adding the Layer Group to the map, all child markers but the checked out ones will cluster. Checked out ones will be directly added to the map, without clustering. What did you expect? :-)

License

Leaflet.MarkerCluster.LayerSupport is distributed under the MIT License (Expat type), like Leaflet.markercluster.