public override List <CKCluster> ClustersInRect(MapKit.MKMapRect rect, double zoom, Tree.ICKAnnotationTree tree)
{
var clusters = new Dictionary <double, CKCluster>();
var annotations = tree.AnnotationsInRect(rect);
var numCells = Math.Ceiling(256 * Math.Pow(2, zoom) / this.CellSize);
foreach (var ann in annotations)
{
var point = MKMapPoint.FromCoordinate(ann.Coordinate);
var col = numCells * point.X / MKMapSize.World.Width;
var row = numCells * point.Y / MKMapSize.World.Height;
var key = numCells * row + col;
CKCluster cluster;
if (clusters.ContainsKey(key))
{
cluster = clusters[key];
}
else
{
cluster = this.ClusterWithCoordinate(ann.Coordinate);
clusters[key] = cluster;
}
cluster.AddAnnotation(ann);
}
return(clusters.Values.ToList());
}
static extern bool MKMapRectContainsRect(MKMapRect rect1, MKMapRect rect2);
static extern bool MKMapRectContainsPoint(MKMapRect rect, MKMapPoint point);