com.spatial4j.core.shape.impl

Class CircleImpl

java.lang.Object

com.spatial4j.core.shape.BaseShape<SpatialContext>

com.spatial4j.core.shape.impl.CircleImpl

All Implemented Interfaces:

Circle, Shape

Direct Known Subclasses:

GeoCircle

public class CircleImpl
extends BaseShape<SpatialContext>
implements Circle

A circle, also known as a point-radius, based on a DistanceCalculator which does all the work. This implementation should work for both cartesian 2D and geodetic sphere surfaces.

Field Summary

Fields

Modifier and Type	Field and Description
protected Rectangle	enclosingBox
protected Point	point
protected double	radiusDEG

Fields inherited from class com.spatial4j.core.shape.BaseShape

ctx

Constructor Summary

Constructors

Constructor and Description
CircleImpl(Point p, double radiusDEG, SpatialContext ctx)

Method Summary

Methods

Modifier and Type	Method and Description
boolean	contains(double x, double y)
static boolean	equals(Circle thiz, Object o) All Circle implementations should use this definition of Object.equals(Object).
boolean	equals(Object obj) The sub-classes of Shape generally implement the same contract for Object.equals(Object) and Object.hashCode() amongst the same sub-interface type.
double	getArea(SpatialContext ctx) Calculates the area of the shape, in square-degrees.
Rectangle	getBoundingBox() Note that the bounding box might contain a minX that is > maxX, due to WGS84 dateline.
Circle	getBuffered(double distance, SpatialContext ctx) Returns a buffered version of this shape.
Point	getCenter() Returns the center point of this shape.
double	getRadius() The distance from the point's center to its edge, measured in the same units as x & y (e.g.
protected double	getXAxis() The X coordinate of where the circle axis intersect.
protected double	getYAxis() The Y coordinate of where the circle axis intersect.
boolean	hasArea() Does the shape have area? This will be false for points and lines.
int	hashCode()
static int	hashCode(Circle thiz) All Circle implementations should use this definition of Object.hashCode().
boolean	isEmpty() Shapes can be "empty", which is to say it exists nowhere.
SpatialRelation	relate(Circle circle)
SpatialRelation	relate(Point point)
SpatialRelation	relate(Rectangle r)
SpatialRelation	relate(Shape other) Describe the relationship between the two objects.
protected SpatialRelation	relateRectanglePhase2(Rectangle r, SpatialRelation bboxSect)
void	reset(double x, double y, double radiusDEG) Expert: Resets the state of this shape given the arguments.
String	toString()

Methods inherited from class com.spatial4j.core.shape.BaseShape

getContext

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.spatial4j.core.shape.Shape

getContext

Field Detail

point

protected final Point point

radiusDEG

protected double radiusDEG

enclosingBox

protected Rectangle enclosingBox

Constructor Detail

CircleImpl

public CircleImpl(Point p,
          double radiusDEG,
          SpatialContext ctx)

Method Detail

reset

public void reset(double x,
         double y,
         double radiusDEG)

Description copied from interface: Circle

Expert: Resets the state of this shape given the arguments. This is a performance feature to avoid excessive Shape object allocation as well as some argument error checking. Mutable shapes is error-prone so use with care.

Specified by:

reset in interface Circle

isEmpty

public boolean isEmpty()

Description copied from interface: Shape

Shapes can be "empty", which is to say it exists nowhere. The underlying coordinates are typically NaN.

Specified by:

isEmpty in interface Shape

getCenter

public Point getCenter()

Description copied from interface: Shape

Returns the center point of this shape. This is usually the same as getBoundingBox().getCenter() but it doesn't have to be.

Postcondition: this.relate(this.getCenter()) == CONTAINS

Specified by:

getCenter in interface Shape

getRadius

public double getRadius()

Description copied from interface: Circle

The distance from the point's center to its edge, measured in the same units as x & y (e.g. degrees if WGS84).

Specified by:

getRadius in interface Circle

getArea

public double getArea(SpatialContext ctx)

Description copied from interface: Shape

Calculates the area of the shape, in square-degrees. If ctx is null then simple Euclidean calculations will be used. This figure can be an estimate.

Specified by:

getArea in interface Shape

getBuffered

public Circle getBuffered(double distance,
                 SpatialContext ctx)

Description copied from interface: Shape

Returns a buffered version of this shape. The buffer is usually a rounded-corner buffer, although some shapes might buffer differently. This is an optional operation.

Specified by:

getBuffered in interface Shape

Returns:

Not null, and the returned shape should contain the current shape.

contains

public boolean contains(double x,
               double y)

hasArea

public boolean hasArea()

Description copied from interface: Shape

Does the shape have area? This will be false for points and lines. It will also be false for shapes that normally have area but are constructed in a degenerate case as to not have area (e.g. a circle with 0 radius or rectangle with no height or no width).

Specified by:

hasArea in interface Shape

getBoundingBox

public Rectangle getBoundingBox()

Note that the bounding box might contain a minX that is > maxX, due to WGS84 dateline.

Specified by:

getBoundingBox in interface Shape

relate

public SpatialRelation relate(Shape other)

Description copied from interface: Shape

Describe the relationship between the two objects. For example

• this is WITHIN other
• this CONTAINS other
• this is DISJOINT other
• this INTERSECTS other

Note that a Shape implementation may choose to return INTERSECTS when the true answer is WITHIN or CONTAINS for performance reasons. If a shape does this then it must document when it does. Ideally the shape will not do this approximation in all circumstances, just sometimes.

If the shapes are equal then the result is CONTAINS (preferred) or WITHIN.

Specified by:

relate in interface Shape

relate

public SpatialRelation relate(Point point)

relate

public SpatialRelation relate(Rectangle r)

relateRectanglePhase2

protected SpatialRelation relateRectanglePhase2(Rectangle r,
                                    SpatialRelation bboxSect)

getYAxis

protected double getYAxis()

The Y coordinate of where the circle axis intersect.

getXAxis

protected double getXAxis()

The X coordinate of where the circle axis intersect.

relate

public SpatialRelation relate(Circle circle)

toString

public String toString()

Overrides:

toString in class Object

equals

public boolean equals(Object obj)

Description copied from interface: Shape

The sub-classes of Shape generally implement the same contract for Object.equals(Object) and Object.hashCode() amongst the same sub-interface type. This means, for example, that multiple Point implementations of different classes are equal if they share the same x & y.

Specified by:

equals in interface Shape

Overrides:

equals in class Object

equals

public static boolean equals(Circle thiz,
             Object o)

All Circle implementations should use this definition of Object.equals(Object).

hashCode

public int hashCode()

Overrides:

hashCode in class Object

hashCode

public static int hashCode(Circle thiz)

All Circle implementations should use this definition of Object.hashCode().