Package org.opengis.geometry

Interface DirectPosition

All Superinterfaces:

Position

@Classifier(DATATYPE)
@UML(identifier="DirectPosition",
     specification=ISO_19107)
public interface DirectPosition
extends Position

Holds the coordinates for a position within some coordinate reference system. Since DirectPositions, as data types, will often be included in larger objects (such as geometries) that have references to coordinate reference system, the getCoordinateReferenceSystem() method may returns null if this particular DirectPosition is included in a larger object with such a reference to a coordinate reference system. In this case, the coordinate reference system is implicitly assumed to take on the value of the containing object's coordinate reference system.

Since:

1.0

Departure from OGC/ISO specification:
The ISO specification defines this interface in the coordinate sub-package. GeoAPI moved this interface into the org.opengis.geometry root package for convenience, because it is extensively used.

Method Summary

Modifier and Type	Method	Description
boolean	equals(Object object)	Compares this direct position with the specified object for equality.
double[]	getCoordinate()	A copy of the coordinates presented as an array of double values.
CoordinateReferenceSystem	getCoordinateReferenceSystem()	The coordinate reference system in which the coordinate tuple is given.
int	getDimension()	The length of coordinate sequence (the number of entries).
double	getOrdinate(int dimension)	Returns the coordinate at the specified dimension.
int	hashCode()	Returns a hash code value for this direct position.
void	setOrdinate(int dimension, double value)	Sets the coordinate value along the specified dimension.

Methods inherited from interface Position

getDirectPosition

Method Detail

getCoordinateReferenceSystem

@UML(identifier="coordinateReferenceSystem",
     obligation=MANDATORY,
     specification=ISO_19107)
CoordinateReferenceSystem getCoordinateReferenceSystem()

The coordinate reference system in which the coordinate tuple is given. May be null if this particular DirectPosition is included in a larger object with such a reference to a coordinate reference system. In this case, the coordinate reference system is implicitly assumed to take on the value of the containing object's coordinate reference system.

Returns:

the coordinate reference system, or null.

getDimension

@UML(identifier="dimension",
     obligation=MANDATORY,
     specification=ISO_19107)
int getDimension()

The length of coordinate sequence (the number of entries). This is determined by the coordinate reference system.

Returns:

the dimensionality of this position.

getCoordinate

@UML(identifier="coordinate",
     obligation=MANDATORY,
     specification=ISO_19107)
double[] getCoordinate()

A copy of the coordinates presented as an array of double values. Please note that this is only a copy (the real values may be stored in another format) so changes to the returned array will not affect the source DirectPosition.

 final int dim = position.getDimension();
 for (int i=0; i<dim; i++) {
     position.getOrdinate(i);       // no copy overhead
 }
 

To manipulate coordinates, the following idiom can be used:

 position.setOrdinate(i, value);    // edit in place
 

There are a couple reasons for requesting a copy:

• We want an array of coordinates with the intent to modify it for computation purpose (without modifying the original DirectPosition), or we want to protect the array from future DirectPosition changes.
• If DirectPosition.getOrdinates() is guaranteed to not return the backing array, then we can work directly on this array. If we don't have this guarantee, then we must conservatively clone the array in every cases.
• Cloning the returned array is useless if the implementation cloned the array or was forced to returns a new array anyway (for example because the coordinates were computed on the fly)

Precedence is given to data integrity over getOrdinates() performance. Performance concern can be avoided with usage of getOrdinate(int).

Returns:

a copy of the coordinates. Changes in the returned array will not be reflected back in this DirectPosition object.

TODO:

needs to be renamed getCoordinates().

getOrdinate

double getOrdinate(int dimension)
            throws IndexOutOfBoundsException

Returns the coordinate at the specified dimension.

Parameters:

dimension - the dimension in the range 0 to dimension-1.

Returns:

the coordinate at the specified dimension.

Throws:

IndexOutOfBoundsException - if the given index is negative or is equals or greater than the position dimension.

TODO:

needs to be renamed getCoordinate(int).

setOrdinate

void setOrdinate(int dimension,
                 double value)
          throws IndexOutOfBoundsException,
                 UnsupportedOperationException

Sets the coordinate value along the specified dimension.

Parameters:

dimension - the dimension for the coordinate of interest.

value - the coordinate value of interest.

Throws:

IndexOutOfBoundsException - if the given index is negative or is equals or greater than the position dimension.

UnsupportedOperationException - if this direct position is immutable.

TODO:

needs to be renamed setCoordinate(int, double).

equals

boolean equals(Object object)

Compares this direct position with the specified object for equality. Two direct positions are considered equal if the following conditions are meet:

• object is non-null and is an instance of DirectPosition.
• Both direct positions have the same number of dimensions.
• Both direct positions have the same or equal coordinate reference system.
• For all dimension i, the coordinate value of both direct positions at that dimension are equals in the sense of Double.equals(Object). In other words, Arrays.equals(getCoordinate(), object.getCoordinate()) returns true.

Overrides:

equals in class Object

Parameters:

object - the object to compare with this direct position for equality.

Returns:

true if the given object is equals to this direct position.

hashCode

int hashCode()

Returns a hash code value for this direct position. This method should returns the same value as: Arrays.hashCode(getCoordinate()) + getCoordinateReferenceSystem().hashCode() where the right hand side of the addition is omitted if the coordinate reference system is null.

Overrides:

hashCode in class Object

Returns:

a hash code value for this direct position.