Strategy for vector feature clustering.
| OpenLayers. | Strategy for vector feature clustering. | 
| Properties | |
| distance | {Integer} Pixel distance between features that should be considered a single cluster. | 
| threshold | {Integer} Optional threshold below which original features will be added to the layer instead of clusters. | 
| features | {Array(OpenLayers.Feature.Vector)} Cached features. | 
| clusters | {Array(OpenLayers.Feature.Vector)} Calculated clusters. | 
| clustering | {Boolean} The strategy is currently clustering features. | 
| resolution | {Float} The resolution (map units per pixel) of the current cluster set. | 
| Constructor | |
| OpenLayers. | Create a new clustering strategy. | 
| Functions | |
| activate | Activate the strategy. | 
| deactivate | Deactivate the strategy. | 
| cacheFeatures | Cache features before they are added to the layer. | 
| clearCache | Clear out the cached features. | 
| cluster | Cluster features based on some threshold distance. | 
| clustersExist | Determine whether calculated clusters are already on the layer. | 
| shouldCluster | Determine whether to include a feature in a given cluster. | 
| addToCluster | Add a feature to a cluster. | 
| createCluster | Given a feature, create a cluster. | 
{Integer} Optional threshold below which original features will be added to the layer instead of clusters. For example, a threshold of 3 would mean that any time there are 2 or fewer features in a cluster, those features will be added directly to the layer instead of a cluster representing those features. Default is null (which is equivalent to 1 - meaning that clusters may contain just one feature).
{Array(OpenLayers.Feature.Vector)} Cached features.
{Array(OpenLayers.Feature.Vector)} Calculated clusters.
shouldCluster: function( cluster, feature ) 
Determine whether to include a feature in a given cluster.
| cluster | {OpenLayers.Feature.Vector} A cluster. | 
| feature | {OpenLayers.Feature.Vector} A feature. | 
{Boolean} The feature should be included in the cluster.
addToCluster: function( cluster, feature ) 
Add a feature to a cluster.
| cluster | {OpenLayers.Feature.Vector} A cluster. | 
| feature | {OpenLayers.Feature.Vector} A feature. | 
createCluster: function( feature ) 
Given a feature, create a cluster.
| feature | {OpenLayers.Feature.Vector} | 
{OpenLayers.Feature.Vector} A cluster.
Activate the strategy.
activate: function() 
Deactivate the strategy.
deactivate: function() 
Cache features before they are added to the layer.
cacheFeatures: function( event ) 
Clear out the cached features.
clearCache: function() 
Cluster features based on some threshold distance.
cluster: function( event ) 
Determine whether calculated clusters are already on the layer.
clustersExist: function() 
Determine whether to include a feature in a given cluster.
shouldCluster: function( cluster, feature ) 
Add a feature to a cluster.
addToCluster: function( cluster, feature ) 
Given a feature, create a cluster.
createCluster: function( feature )