org.geolatte.geom

Class Polygon

java.lang.Object

org.geolatte.geom.Geometry

org.geolatte.geom.Polygon

All Implemented Interfaces:

Serializable, Iterable<LinearRing>

public class Polygon
extends Geometry
implements Iterable<LinearRing>

A planar surface defined by 1 exterior boundary and 0 or more interior boundaries. Each interior boundary defines a hole in the Polygon.

The exterior boundary LinearRing defines the "top" of the surface which is the side of the surface from which the exterior boundary appears to traverse the boundary in a counter clockwise direction. The interior LinearRings will have the opposite orientation and appear as clockwise when viewed from the "top".

The rules that define valid Polygons are as follows

1. Polygons are topologically closed;
2. The boundary of a Polygon consists of a set of LinearRings that make up its exterior and interior boundaries;
3. No two rings in the boundary cross and the rings in the boundary of a Polygon may intersect at a Point but only as a tangent
4. A Polygon may not have cut lines, spikes or punctures;
5. The interior of every Polygon is a connected point set;
6. The exterior of a Polygon with 1 or more holes is not connected. Each hole defines a connected component of the exterior

Author:

Karel Maesen, Geovise BVBA creation-date: 4/14/11

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
Polygon(LinearRing[] rings) Creates a Polygon with the specified array of exterior and interior boundaries.
Polygon(PointSequence pointSequence) Creates a Polygon with no holes, and having the specified PointSequence as exterior boundary
Polygon(PointSequence pointSequence, GeometryOperations ops) Creates a Polygon with no holes, and having the specified PointSequence as exterior boundary

Method Summary

Modifier and Type	Method and Description
void	accept(GeometryVisitor visitor) Accepts a GeometryVisitor.
static Polygon	createEmpty() Creates an empty Polygon.
double	getArea() Returns the area of this Polygon as measured in the CoordinateReferenceSystem of this Polygon.
MultiLineString	getBoundary() Returns the boundary of this Geometry.
Point	getCentroid() Returns the mathematical centroid for this Polygon.
int	getDimension() Returns the topological dimension of this instance.
LinearRing	getExteriorRing() Returns the exterior boundary of this Polygon.
GeometryType	getGeometryType() Returns the type of this Geometry.
LinearRing	getInteriorRingN(int index) Returns the specified interior ring.
int	getNumInteriorRing() returns the number of interior boundaries.
Point	getPointOnSurface() Returns a Point that is guaranteed to lie on this Polygon.
PointCollection	getPoints() Returns the PointCollection that is associated with this instance
Iterator<LinearRing>	iterator() Returns an Iterator over the boundaries of this Polygon.

Methods inherited from class org.geolatte.geom.Geometry

asBinary, asText, buffer, collectPointSets, contains, convexHull, crosses, difference, disjoint, distance, equals, getCoordinateDimension, getCrsId, getCrsId, getDimensionalFlag, getEnvelope, getGeometryOperations, getGeometryOperations, getNumPoints, getPointN, getSRID, hashCode, intersection, intersects, is3D, isEmpty, isMeasured, isSimple, locateAlong, locateBetween, overlaps, relate, symDifference, toString, touches, union, within

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

Polygon

public Polygon(PointSequence pointSequence,
               GeometryOperations ops)

Creates a Polygon with no holes, and having the specified PointSequence as exterior boundary

Parameters:

pointSequence - the PointSequence representing the exterior boundary

ops - the GeometryOperatoins implementation for the constructed Polygon

Throws:

IllegalArgumentException - when the specified PointSequence does not form a LinearRing (i.e., is empty or not closed).

Polygon

public Polygon(PointSequence pointSequence)

Creates a Polygon with no holes, and having the specified PointSequence as exterior boundary

Parameters:

pointSequence - the PointSequence representing the exterior boundary

Throws:

IllegalArgumentException - when the specified PointSequence does not form a LinearRing (i.e., is empty or not closed).

Polygon

public Polygon(LinearRing[] rings)

Creates a Polygon with the specified array of exterior and interior boundaries.

Parameters:

rings - the array of the Polygon's boundaries: the first element is the exterior boundary, all subsequent rings represent interior boundaries.

Throws:

IllegalArgumentException - when the specified PointSequence does not form a LinearRing (i.e., is empty or not closed).

Method Detail

createEmpty

public static Polygon createEmpty()

Creates an empty Polygon.

Returns:

an empty Polygon.

getPoints

public PointCollection getPoints()

Description copied from class: Geometry

Returns the PointCollection that is associated with this instance

Specified by:

getPoints in class Geometry

Returns:

getExteriorRing

public LinearRing getExteriorRing()

Returns the exterior boundary of this Polygon.

Returns:

a LinearRing representing the exterior boundary of this Polygon.

getNumInteriorRing

public int getNumInteriorRing()

returns the number of interior boundaries.

Returns:

the number of interior boundaries

getInteriorRingN

public LinearRing getInteriorRingN(int index)

Returns the specified interior ring.

Parameters:

index - the (zero-based) position of the interior boundary in the list of interior boundaries.

Returns:

the LinearRing at the position specified by the parameter index.

getArea

public double getArea()

Returns the area of this Polygon as measured in the CoordinateReferenceSystem of this Polygon.

Returns:

the area of this Polygon.

getCentroid

public Point getCentroid()

Returns the mathematical centroid for this Polygon.

The result is not guaranteed to be on this surface.

Returns:

the centroid Point for this Polygon

getPointOnSurface

public Point getPointOnSurface()

Returns a Point that is guaranteed to lie on this Polygon.

Returns:

a Point on this Polygon

getDimension

public int getDimension()

Description copied from class: Geometry

Returns the topological dimension of this instance. In non-homogenous collections, this will return the largest topological dimension of the contained Geometries.

Specified by:

getDimension in class Geometry

Returns:

getGeometryType

public GeometryType getGeometryType()

Description copied from class: Geometry

Returns the type of this Geometry.

Specified by:

getGeometryType in class Geometry

Returns:

the GeometryType of this instance.

getBoundary

public MultiLineString getBoundary()

Description copied from class: Geometry

Returns the boundary of this Geometry.

Overrides:

getBoundary in class Geometry

Returns:

iterator

public Iterator<LinearRing> iterator()

Returns an Iterator over the boundaries of this Polygon.

The boundaries are returned in order, with the first element being the exterior boundary.

Specified by:

iterator in interface Iterable<LinearRing>

Returns:

accept

public void accept(GeometryVisitor visitor)

Description copied from class: Geometry

Accepts a GeometryVisitor.

If this Geometry instance is a GeometryCollection then it will pass the visitor to its contained Geometries.

Specified by:

accept in class Geometry