Package org.geotools.geometry.jts.coordinatesequence

Class CoordinateSequences

Object

CoordinateSequences

CoordinateSequences

public class CoordinateSequences
extends CoordinateSequences

Utility functions for coordinate sequences (extends the same named JTS class)

Author:

Andrea Aime - OpenGeo, Martin Davis - OpenGeo

Constructor Summary

Constructors

Constructor	Description
CoordinateSequences()

Method Summary

Modifier and Type	Method	Description
static int	carriedMeasures(CoordinateSequence sequence)	Measures the sequence really carries, zero when the M ordinate is not filled in: a shapefile PolyLineZ declares a measure and leaves it NaN.
static int	computeOrientation(CoordinateSequence cs, int p1, int p2, int q)
static int	coordinateDimension(CoordinateSequence seq)	Gets the effective dimension of a CoordinateSequence.
static int	coordinateDimension(Geometry g)	Gets the dimension of the coordinates in a Geometry, by reading it from a component CoordinateSequence.
static boolean	equalsND(Geometry g1, Geometry g2)	Returns true if the two geometries are equal in N dimensions (normal geometry equality is only 2D)
static CoordinateSequence	firstSequence(Geometry g)	First coordinate sequence of a geometry in Geometry.apply(CoordinateSequenceFilter) order, null when the geometry holds none.
static boolean	isCCW(CoordinateSequence ring)	Computes whether a ring defined by an array of Coordinates is oriented counter-clockwise.
static int[]	ordinateIndices(CoordinateSequence sequence, boolean includeMeasures)	Ordinate indices to read for a coordinate, in encoding order: X, Y, the height when the sequence fills one, then the measures when asked for.
static int	spatialDimension(CoordinateSequence sequence)	X, Y and the height when the sequence carries a usable one.

Methods inherited from class CoordinateSequences

copy, copyCoord, ensureValidRing, extend, indexOf, isEqual, isRing, minCoordinate, minCoordinateIndex, minCoordinateIndex, reverse, scroll, scroll, scroll, swap, toString

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

CoordinateSequences

public CoordinateSequences()

Method Details

isCCW

public static boolean isCCW(CoordinateSequence ring)

Computes whether a ring defined by an array of Coordinates is oriented counter-clockwise.

• The list of points is assumed to have the first and last points equal.
• This will handle coordinate lists which contain repeated points.

This algorithm is only guaranteed to work with valid rings. If the ring is invalid (e.g. self-crosses or touches), the computed result may not be correct.

Parameters:

ring - an array of Coordinates forming a ring

Returns:

true if the ring is oriented counter-clockwise.

computeOrientation

public static int computeOrientation(CoordinateSequence cs,
 int p1,
 int p2,
 int q)

firstSequence

public static CoordinateSequence firstSequence(Geometry g)

First coordinate sequence of a geometry in Geometry.apply(CoordinateSequenceFilter) order, null when the geometry holds none. It is the same sequence coordinateDimension(Geometry) reads its answer from.

coordinateDimension

public static int coordinateDimension(Geometry g)

Gets the dimension of the coordinates in a Geometry, by reading it from a component CoordinateSequence. This will be usually either 2 or 3.

Parameters:

g - a Geometry

Returns:

the dimension of the coordinates in the Geometry

coordinateDimension

public static int coordinateDimension(CoordinateSequence seq)

Gets the effective dimension of a CoordinateSequence. This is a workaround for the issue that CoordinateArraySequence does not keep an accurate dimension - it always reports dim=3, even if there is no Z ordinate (ie they are NaN). This method checks for that case and reports dim=2. Only the first coordinate is checked.

There is one small hole: if a CoordinateArraySequence is empty, the dimension will be reported as 3.

Parameters:

seq - a CoordinateSequence

Returns:

the effective dimension of the coordinate sequence

ordinateIndices

public static int[] ordinateIndices(CoordinateSequence sequence,
 boolean includeMeasures)

Ordinate indices to read for a coordinate, in encoding order: X, Y, the height when the sequence fills one, then the measures when asked for. Callers write exactly these ordinates, so what is counted and what is written can never disagree.

spatialDimension

public static int spatialDimension(CoordinateSequence sequence)

X, Y and the height when the sequence carries a usable one. Measured sequences report their layout faithfully, so the declared dimension is used, while the heuristic is needed for the rest because CoordinateArraySequence reports three ordinates even for plain 2D data.

carriedMeasures

public static int carriedMeasures(CoordinateSequence sequence)

Measures the sequence really carries, zero when the M ordinate is not filled in: a shapefile PolyLineZ declares a measure and leaves it NaN. Only the first coordinate is checked, like the dimension is, so measures are all-or-nothing per geometry: a NaN measure on a later coordinate is encoded as NaN.

equalsND

public static boolean equalsND(Geometry g1,
 Geometry g2)

Returns true if the two geometries are equal in N dimensions (normal geometry equality is only 2D)