org.apache.sis.geometry

Class AbstractEnvelope

Object

AbstractEnvelope

All Implemented Interfaces:

Emptiable, Envelope

Direct Known Subclasses:

GeneralEnvelope, ImmutableEnvelope

public abstract class AbstractEnvelope
extends Object
implements Envelope, Emptiable

Default implementations of most Envelope methods, leaving the data storage to subclasses. This base class does not hold any state and does not implement the Serializable or Cloneable interfaces. The internal representation, and the choice to be cloneable or serializable, is left to subclasses.

Implementors needs to define at least the following methods:

• Envelope.get­Dimension()
• Envelope.get­Coordinate­Reference­System()
• get­Lower(int)
• get­Upper(int)

All other methods, including to­String(), equals(Object) and hash­Code(), are implemented on top of the above four methods.

Spanning the anti-meridian of a Geographic CRS

The Web Coverage Service (WCS) specification authorizes (with special treatment) cases where upper < lower at least in the longitude case. They are envelopes crossing the anti-meridian, like the red box below (the green box is the usual case). The default implementation of methods listed in the right column can handle such cases.

Supported methods: get­Minimum(int) get­Maximum(int) get­Median(int) get­Span(int) to­Simple­Envelopes() contains(Direct­Position) contains(Envelope) intersects(Envelope)

Choosing the range of longitude values

Geographic CRS typically have longitude values in the [-180 … +180]° range, but the [0 … 360]° range is also occasionally used. Users of this class need to ensure that this envelope CRS is associated to axes having the desired minimum and maximum value.

Note on positive and negative zeros

The IEEE 754 standard defines two different values for positive zero and negative zero. When used with SIS envelopes and keeping in mind the above discussion, those zeros have different meanings:

• The [-0…0]° range is an empty envelope.
• The [0…-0]° range makes a full turn around the globe, like the [-180…180]° range except that the former range spans across the anti-meridian.

Since:

0.3

Defined in the sis-referencing module

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractEnvelope() Constructs an envelope.

Method Summary

Modifier and Type	Method and Description
static AbstractEnvelope	castOrCopy(Envelope envelope) Returns the given envelope as an Abstract­Envelope instance.
boolean	contains(DirectPosition position) Tests if a specified coordinate is inside the boundary of this envelope.
boolean	contains(Envelope envelope) Returns true if this envelope completely encloses the specified envelope.
boolean	contains(Envelope envelope, boolean edgesInclusive) Returns true if this envelope completely encloses the specified envelope.
boolean	equals(Envelope other, double eps, boolean epsIsRelative) Compares to the specified envelope for equality up to the specified tolerance value.
boolean	equals(Object object) Returns true if the specified object is an envelope of the same class with equals coordinates and CRS.
abstract double	getLower(int dimension) Returns the limit in the direction of decreasing ordinate values in the specified dimension.
DirectPosition	getLowerCorner() A coordinate position consisting of all the lower ordinate values.
double	getMaximum(int dimension) Returns the maximal ordinate value for the specified dimension.
DirectPosition	getMedian() A coordinate position consisting of all the median ordinate values.
double	getMedian(int dimension) Returns the median ordinate along the specified dimension.
double	getMinimum(int dimension) Returns the minimal ordinate value for the specified dimension.
double	getSpan(int dimension) Returns the envelope span (typically width or height) along the specified dimension.
double	getSpan(int dimension, Unit<?> unit) Returns the envelope span along the specified dimension, in terms of the given units.
abstract double	getUpper(int dimension) Returns the limit in the direction of increasing ordinate values in the specified dimension.
DirectPosition	getUpperCorner() A coordinate position consisting of all the upper ordinate values.
int	hashCode() Returns a hash value for this envelope.
boolean	intersects(Envelope envelope) Returns true if this envelope intersects the specified envelope.
boolean	intersects(Envelope envelope, boolean touch) Returns true if this envelope intersects or (optionally) touches the specified envelope.
boolean	isAllNaN() Returns false if at least one ordinate value is not NaN.
boolean	isEmpty() Determines whether or not this envelope is empty.
Envelope[]	toSimpleEnvelopes() Returns this envelope as an array of simple (without wraparound) envelopes.
String	toString() Formats this envelope as a "BOX" element.

Methods inherited from class Object

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

Methods inherited from interface Envelope

get­Coordinate­Reference­System, get­Dimension

Constructor Detail

AbstractEnvelope

protected AbstractEnvelope()

Constructs an envelope.

Method Detail

castOrCopy

public static AbstractEnvelope castOrCopy(Envelope envelope)

Returns the given envelope as an Abstract­Envelope instance. If the given envelope is already an instance of Abstract­Envelope, then it is returned unchanged. Otherwise the coordinate values and the CRS of the given envelope are copied in a new envelope.

Parameters:

envelope - the envelope to cast, or null.

Returns:

the values of the given envelope as an Abstract­Envelope instance.

See Also:

General­Envelope.cast­Or­Copy(Envelope), Immutable­Envelope.cast­Or­Copy(Envelope)

getLowerCorner

public DirectPosition getLowerCorner()

A coordinate position consisting of all the lower ordinate values. The default implementation returns a view over the get­Lower(int) method, so changes in this envelope will be immediately reflected in the returned direct position. If the particular case of the General­Envelope subclass, the returned position supports also write operations, so changes in the position are reflected back in the envelope.

Note: The Web Coverage Service (WCS) 1.1 specification uses an extended interpretation of the bounding box definition. In a WCS 1.1 data structure, the lower corner defines the edges region in the directions of decreasing coordinate values in the envelope CRS. This is usually the algebraic minimum coordinates, but not always. For example, an envelope crossing the anti-meridian could have a lower corner longitude greater than the upper corner longitude. Such extended interpretation applies mostly to axes having WRAPAROUND range meaning.

Specified by:

get­Lower­Corner in interface Envelope

Returns:

a view over the lower corner, typically (but not necessarily) containing minimal ordinate values.

getUpperCorner

public DirectPosition getUpperCorner()

A coordinate position consisting of all the upper ordinate values. The default implementation returns a view over the get­Upper(int) method, so changes in this envelope will be immediately reflected in the returned direct position. If the particular case of the General­Envelope subclass, the returned position supports also write operations, so changes in the position are reflected back in the envelope.

Note: The Web Coverage Service (WCS) 1.1 specification uses an extended interpretation of the bounding box definition. In a WCS 1.1 data structure, the upper corner defines the edges region in the directions of increasing coordinate values in the envelope CRS. This is usually the algebraic maximum coordinates, but not always. For example, an envelope crossing the anti-meridian could have an upper corner longitude less than the lower corner longitude. Such extended interpretation applies mostly to axes having WRAPAROUND range meaning.

Specified by:

get­Upper­Corner in interface Envelope

Returns:

a view over the upper corner, typically (but not necessarily) containing maximal ordinate values.

getMedian

public DirectPosition getMedian()

A coordinate position consisting of all the median ordinate values. The default implementation returns a view over the get­Median(int) method, so changes in this envelope will be immediately reflected in the returned direct position.

Returns:

the median coordinates.

getLower

public abstract double getLower(int dimension)
                         throws IndexOutOfBoundsException

Returns the limit in the direction of decreasing ordinate values in the specified dimension. This is usually the algebraic minimum, except if this envelope spans the anti-meridian.

Parameters:

dimension - the dimension for which to obtain the ordinate value.

Returns:

the starting ordinate value at the given dimension.

Throws:

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

getUpper

public abstract double getUpper(int dimension)
                         throws IndexOutOfBoundsException

Returns the limit in the direction of increasing ordinate values in the specified dimension. This is usually the algebraic maximum, except if this envelope spans the anti-meridian.

Parameters:

dimension - the dimension for which to obtain the ordinate value.

Returns:

the starting ordinate value at the given dimension.

Throws:

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

getMinimum

public double getMinimum(int dimension)
                  throws IndexOutOfBoundsException

Returns the minimal ordinate value for the specified dimension. In the typical case of non-empty envelopes not spanning the anti-meridian, this method returns the get­Lower(int) value verbatim. In the case of envelope spanning the anti-meridian, this method returns the axis minimum value. If the range in the given dimension is invalid, then this method returns Na­N.

Specified by:

get­Minimum in interface Envelope

Parameters:

dimension - the dimension for which to obtain the ordinate value.

Returns:

the minimal ordinate value at the given dimension.

Throws:

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

getMaximum

public double getMaximum(int dimension)
                  throws IndexOutOfBoundsException

Returns the maximal ordinate value for the specified dimension. In the typical case of non-empty envelopes not spanning the anti-meridian, this method returns the get­Upper(int) value verbatim. In the case of envelope spanning the anti-meridian, this method returns the axis maximum value. If the range in the given dimension is invalid, then this method returns Na­N.

Specified by:

get­Maximum in interface Envelope

Parameters:

dimension - the dimension for which to obtain the ordinate value.

Returns:

the maximal ordinate value at the given dimension.

Throws:

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

getMedian

public double getMedian(int dimension)
                 throws IndexOutOfBoundsException

Returns the median ordinate along the specified dimension. In most cases, the result is equals (minus rounding error) to:

median = (getUpper(dimension) + getLower(dimension)) / 2;

Spanning the anti-meridian of a Geographic CRS

If upper < lower and the range meaning for the requested dimension is wraparound, then the median calculated above is actually in the middle of the space outside the envelope. In such cases, this method shifts the median value by half of the periodicity (180° in the longitude case) in order to switch from outer space to inner space. If the axis range meaning is not WRAPAROUND, then this method returns Na­N.

Specified by:

get­Median in interface Envelope

Parameters:

dimension - the dimension for which to obtain the ordinate value.

Returns:

the median ordinate at the given dimension, or Double.Na­N.

Throws:

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

getSpan

public double getSpan(int dimension)

Returns the envelope span (typically width or height) along the specified dimension. In most cases, the result is equals (minus rounding error) to:

span = getUpper(dimension) - getLower(dimension);

Spanning the anti-meridian of a Geographic CRS

If upper < lower and the range meaning for the requested dimension is wraparound, then the span calculated above is negative. In such cases, this method adds the periodicity (typically 360° of longitude) to the span. If the result is a positive number, it is returned. Otherwise this method returns Na­N.

Specified by:

get­Span in interface Envelope

Parameters:

dimension - the dimension for which to obtain the span.

Returns:

the span (typically width or height) at the given dimension, or Double.Na­N.

Throws:

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

getSpan

public double getSpan(int dimension,
                      Unit<?> unit)
               throws IndexOutOfBoundsException,
                      IncommensurableException

Returns the envelope span along the specified dimension, in terms of the given units. The default implementation invokes get­Span(int) and converts the result.

Parameters:

dimension - the dimension to query.

unit - the unit for the return value.

Returns:

the span in terms of the given unit.

Throws:

Index­Out­Of­Bounds­Exception - if the given index is out of bounds.

Incommensurable­Exception - if the length can't be converted to the specified units.

toSimpleEnvelopes

public Envelope[] toSimpleEnvelopes()

Returns this envelope as an array of simple (without wraparound) envelopes. The length of the returned array depends on the number of dimensions where a wraparound range is found. Typically, wraparound occurs only in the range of longitude values, when the range crosses the anti-meridian (a.k.a. date line). However this implementation will take in account any axis having wraparound range meaning.

Special cases:

• If this envelope is empty, then this method returns an empty array.
• If this envelope does not have any wraparound behavior, then this method returns this in an array of length 1. This envelope is not cloned.
• If this envelope crosses the anti-meridian (a.k.a. date line) then this method represents this envelope as two separated simple envelopes.
• While uncommon, the envelope could theoretically crosses the limit of other axis having wraparound range meaning. If wraparound occur along n axes, then this method represents this envelope as 2ⁿ separated simple envelopes.

Returns:

a representation of this envelope as an array of non-empty envelope.

Since:

0.4

See Also:

Envelope2D.to­Rectangles(), General­Envelope.simplify()

isEmpty

public boolean isEmpty()

Determines whether or not this envelope is empty. An envelope is empty if it has zero dimension, or if the span of at least one axis is negative, 0 or Na­N.

Note: Strictly speaking, there is an ambiguity if a span is Na­N or if the envelope contains both 0 and infinite spans (since 0⋅∞ = Na­N). In such cases, this method arbitrarily ignores the infinite values and returns true.

If is­Empty() returns false, then is­All­Na­N() is guaranteed to also return false. However the converse is not always true.

Specified by:

is­Empty in interface Emptiable

Returns:

true if this envelope is empty.

See Also:

Default­Geographic­Bounding­Box.is­Empty(), Rectangular­Shape.is­Empty()

isAllNaN

public boolean isAllNaN()

Returns false if at least one ordinate value is not NaN. This is­All­Na­N() check is different than the is­Empty() check since it returns false for a partially initialized envelope, while is­Empty() returns false only after all dimensions have been initialized. More specifically, the following rules apply:

• If is­All­Na­N() == true, then is­Empty() == true
• If is­Empty() == false, then is­All­Na­N() == false
• The converse of the above-cited rules are not always true.

Note that an all-NaN envelope can still have a non-null coordinate reference system.

Returns:

true if this envelope has NaN values.

See Also:

General­Envelope.set­To­Na­N(), Default­Geographic­Bounding­Box.is­Empty()

contains

public boolean contains(DirectPosition position)
                 throws MismatchedDimensionException

Tests if a specified coordinate is inside the boundary of this envelope. If it least one ordinate value in the given point is Na­N, then this method returns false.

Pre-conditions

This method assumes that the specified point uses the same CRS than this envelope. For performance reasons, it will no be verified unless Java assertions are enabled.

Spanning the anti-meridian of a Geographic CRS

For any dimension, if upper < lower then this method uses an algorithm which is the opposite of the usual one: rather than testing if the given point is inside the envelope interior, this method tests if the given point is outside the envelope exterior.

Parameters:

position - the point to text.

Returns:

true if the specified coordinate is inside the boundary of this envelope; false otherwise.

Throws:

Mismatched­Dimension­Exception - if the specified point doesn't have the expected dimension.

Assertion­Error - if assertions are enabled and the envelopes have mismatched CRS.

contains

public boolean contains(Envelope envelope)
                 throws MismatchedDimensionException

Returns true if this envelope completely encloses the specified envelope. The default implementation delegates to:

contains(envelope, true)

Pre-conditions

This method assumes that the specified envelope uses the same CRS than this envelope. For performance reasons, it will no be verified unless Java assertions are enabled.

Spanning the anti-meridian of a Geographic CRS

For every cases illustrated below, the yellow box is considered completely enclosed in the blue envelope:

Parameters:

envelope - the envelope to test for inclusion.

Returns:

true if this envelope completely encloses the specified one.

Throws:

Mismatched­Dimension­Exception - if the specified envelope doesn't have the expected dimension.

Assertion­Error - if assertions are enabled and the envelopes have mismatched CRS.

Since:

0.4

See Also:

intersects(Envelope), equals(Envelope, double, boolean)

contains

public boolean contains(Envelope envelope,
                        boolean edgesInclusive)
                 throws MismatchedDimensionException

Returns true if this envelope completely encloses the specified envelope. If one or more edges from the specified envelope coincide with an edge from this envelope, then this method returns true only if edges­Inclusive is true.

This method is subject to the same pre-conditions than contains(Envelope), and handles envelopes spanning the anti-meridian in the same way.

Parameters:

envelope - the envelope to test for inclusion.

edges­Inclusive - true if this envelope edges are inclusive.

Returns:

true if this envelope completely encloses the specified one.

Throws:

Mismatched­Dimension­Exception - if the specified envelope doesn't have the expected dimension.

Assertion­Error - if assertions are enabled and the envelopes have mismatched CRS.

See Also:

intersects(Envelope, boolean)

intersects

public boolean intersects(Envelope envelope)
                   throws MismatchedDimensionException

Returns true if this envelope intersects the specified envelope. This method returns true if two envelope interiors have at least one point in common (in other words, their intersection is non-empty). The default implementation delegates to:

intersects(envelope, false)

Pre-conditions

This method assumes that the specified envelope uses the same CRS than this envelope. For performance reasons, it will no be verified unless Java assertions are enabled.

Spanning the anti-meridian of a Geographic CRS

This method can handle envelopes spanning the anti-meridian.

Parameters:

envelope - the envelope to test for intersection.

Returns:

true if this envelope intersects the specified one.

Throws:

Mismatched­Dimension­Exception - if the specified envelope doesn't have the expected dimension.

Assertion­Error - if assertions are enabled and the envelopes have mismatched CRS.

Since:

0.4

See Also:

contains(Envelope, boolean), equals(Envelope, double, boolean)

intersects

public boolean intersects(Envelope envelope,
                          boolean touch)
                   throws MismatchedDimensionException

Returns true if this envelope intersects or (optionally) touches the specified envelope. The touch argument controls the value to return if only the envelope boundaries (not the interiors) have a point in common:

• If false, this method returns true if the intersection between the two envelopes is non-empty (i.e. the envelope interiors have points in common). This is the usual definition of intersects operation.
• If true, this method returns true if the two envelopes intersect each other or touch each other.

This method is subject to the same pre-conditions than intersects(Envelope), and handles envelopes spanning the anti-meridian in the same way.

Parameters:

envelope - the envelope to test for intersection.

touch - the value to return if the two envelopes touch each other.

Returns:

true if this envelope intersects the specified envelope, or touch if this envelope touches the specified envelope, or false otherwise.

Throws:

Mismatched­Dimension­Exception - if the specified envelope does not have the expected dimension.

Assertion­Error - if assertions are enabled and the envelopes have mismatched CRS.

See Also:

contains(Envelope, boolean), equals(Envelope, double, boolean)

equals

public boolean equals(Envelope other,
                      double eps,
                      boolean epsIsRelative)

Compares to the specified envelope for equality up to the specified tolerance value. The tolerance value eps can be either relative to the envelope span along each dimension or can be an absolute value (as for example some ground resolution of a grid coverage).

• If eps­Is­Relative is set to true, the actual tolerance value for a given dimension i is eps × span where span is the maximum of this envelope span and the specified envelope span along dimension i.
• If eps­Is­Relative is set to false, the actual tolerance value for a given dimension i is eps.

Note: Relative tolerance values (as opposed to absolute tolerance values) help to workaround the fact that tolerance value are CRS dependent. For example the tolerance value need to be smaller for geographic CRS than for UTM projections, because the former typically has a [-180…180]° range while the later can have a range of thousands of meters.

Coordinate Reference System

To be considered equal, the two envelopes must have the same dimension and their CRS must be equals, ignoring metadata. If at least one envelope has a null CRS, then the CRS are ignored and the ordinate values are compared as if the CRS were equal.

Parameters:

other - the envelope to compare with.

eps - the tolerance value to use for numerical comparisons.

eps­Is­Relative - true if the tolerance value should be relative to axis length, or false if it is an absolute value.

Returns:

true if the given object is equal to this envelope up to the given tolerance value.

See Also:

contains(Envelope), intersects(Envelope)

equals

public boolean equals(Object object)

Returns true if the specified object is an envelope of the same class with equals coordinates and CRS.

Implementation note: This implementation requires that the provided object argument is of the same class than this envelope. We do not relax this rule since not every implementations in the SIS code base follow the same contract.

Overrides:

equals in class Object

Parameters:

object - the object to compare with this envelope.

Returns:

true if the given object is equal to this envelope.

hashCode

public int hashCode()

Returns a hash value for this envelope.

Overrides:

hash­Code in class Object

toString

public String toString()

Formats this envelope as a "BOX" element. The output is of the form "BOXnD(lower corner,upper corner)" where n is the number of dimensions. The number of dimension is written only if different than 2.

Example:

• BOX(-90 -180, 90 180)
• BOX3D(-90 -180 0, 90 180 1)

Note: The BOX element is not part of the standard Well Known Text (WKT) format. However it is understood by many software libraries, for example GDAL and PostGIS.

The string returned by this method can be parsed by the General­Envelope constructor.

Overrides:

to­String in class Object

Returns:

this envelope as a BOX or BOX3D (most typical dimensions) element.