com.vividsolutions.jts.index.quadtree
Class Quadtree

java.lang.Object
  extended bycom.vividsolutions.jts.index.quadtree.Quadtree
All Implemented Interfaces:
SpatialIndex

public class Quadtree
extends java.lang.Object
implements SpatialIndex

A Quadtree is a spatial index structure for efficient querying of 2D rectangles. If other kinds of spatial objects need to be indexed they can be represented by their envelopes

The quadtree structure is used to provide a primary filter for range rectangle queries. The query() method returns a list of all objects which may intersect the query rectangle. Note that it may return objects which do not in fact intersect. A secondary filter is required to test for exact intersection. Of course, this secondary filter may consist of other tests besides intersection, such as testing other kinds of spatial relationships.

This implementation does not require specifying the extent of the inserted items beforehand. It will automatically expand to accomodate any extent of dataset.

This data structure is also known as an MX-CIF quadtree following the usage of Samet and others.

Version:
1.7

Constructor Summary
Quadtree()
          Constructs a Quadtree with zero items.
 
Method Summary
 int depth()
          Returns the number of levels in the tree.
static Envelope ensureExtent(Envelope itemEnv, double minExtent)
          Ensure that the envelope for the inserted item has non-zero extents.
 void insert(Envelope itemEnv, java.lang.Object item)
          Adds a spatial item with an extent specified by the given Envelope to the index
 java.util.List query(Envelope searchEnv)
          Queries the index for all items whose extents intersect the given search Envelope Note that some kinds of indexes may also return objects which do not in fact intersect the query envelope.
 void query(Envelope searchEnv, ItemVisitor visitor)
          Queries the index for all items whose extents intersect the given search Envelope, and applies an ItemVisitor to them.
 java.util.List queryAll()
          Return a list of all items in the Quadtree
 boolean remove(Envelope itemEnv, java.lang.Object item)
          Removes a single item from the tree.
 int size()
          Returns the number of items in the tree.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

Quadtree

public Quadtree()
Constructs a Quadtree with zero items.

Method Detail

ensureExtent

public static Envelope ensureExtent(Envelope itemEnv,
                                    double minExtent)
Ensure that the envelope for the inserted item has non-zero extents. Use the current minExtent to pad the envelope, if necessary


depth

public int depth()
Returns the number of levels in the tree.


size

public int size()
Returns the number of items in the tree.

Returns:
the number of items in the tree

insert

public void insert(Envelope itemEnv,
                   java.lang.Object item)
Description copied from interface: SpatialIndex
Adds a spatial item with an extent specified by the given Envelope to the index

Specified by:
insert in interface SpatialIndex

remove

public boolean remove(Envelope itemEnv,
                      java.lang.Object item)
Removes a single item from the tree.

Specified by:
remove in interface SpatialIndex
Parameters:
itemEnv - the Envelope of the item to remove
item - the item to remove
Returns:
true if the item was found

query

public java.util.List query(Envelope searchEnv)
Description copied from interface: SpatialIndex
Queries the index for all items whose extents intersect the given search Envelope Note that some kinds of indexes may also return objects which do not in fact intersect the query envelope.

Specified by:
query in interface SpatialIndex
Parameters:
searchEnv - the envelope to query for
Returns:
a list of the items found by the query

query

public void query(Envelope searchEnv,
                  ItemVisitor visitor)
Description copied from interface: SpatialIndex
Queries the index for all items whose extents intersect the given search Envelope, and applies an ItemVisitor to them. Note that some kinds of indexes may also return objects which do not in fact intersect the query envelope.

Specified by:
query in interface SpatialIndex
Parameters:
searchEnv - the envelope to query for
visitor - a visitor object to apply to the items found

queryAll

public java.util.List queryAll()
Return a list of all items in the Quadtree