org.openimaj.math.geometry.shape

Class Circle

java.lang.Object

org.openimaj.math.geometry.shape.Circle

All Implemented Interfaces:

Cloneable, GeometricObject2d, Shape

Direct Known Subclasses:

HoughCircles.WeightedCircle

public class Circle
extends Object
implements Shape

A circle shape

Author:

Jonathon Hare (jsh2@ecs.soton.ac.uk)

Field Summary

Fields

Modifier and Type	Field and Description
protected Point2d	centre
protected float	radius

Constructor Summary

Constructors

Constructor and Description
Circle(Circle c) Construct a circle with the given circle
Circle(float x, float y, float radius) Construct a circle with the given position and radius
Circle(Point2d centre, float radius) Construct a circle with the given position and radius

Method Summary

Modifier and Type	Method and Description
Polygon	asPolygon() Convert the shape to a polygon representation
double	calculateArea() Calculate the area of the shape
Point2d	calculateCentroid() Calculate the centroid of the shape
double	calculatePerimeter() Calculate the perimeter of the shape
Rectangle	calculateRegularBoundingBox() Compute the regular (oriented to the axes) bounding box of the shape.
Circle	clone()
boolean	equals(Object obj)
double	getHeight()
float	getRadius()
double	getWidth()
float	getX()
float	getY()
double	intersectionArea(Shape that) Calls Polygon.intersectionArea(Shape, int) with 1 step per pixel dimension.
double	intersectionArea(Shape that, int nStepsPerDimention) Return an estimate for the area of the intersection of this polygon and another polygon.
boolean	isConvex() Test if the shape is convex.
boolean	isInside(Point2d point) Test whether the point p is inside the shape.
double	maxX()
double	maxY()
RotatedRectangle	minimumBoundingRectangle() Compute the minimum size rotated bounding rectangle that contains this shape.
double	minX()
double	minY()
void	scale(float sc) Scale the shape by the given amount about (0,0).
void	scale(Point2d centre, float sc) Scale the shape by the given amount about the given point.
void	scaleCentroid(float sc) Scale the shape about its centroid.
void	setRadius(float r) Set the radius of the circle.
void	setX(float x) Set the x-ordinate of the centre of the circle.
void	setY(float y) Set the y-ordinate of the centre of the circle.
String	toString()
Shape	transform(Jama.Matrix transform) Apply a 3x3 transform matrix to a copy of the GeometricObject2d and return it
void	translate(float x, float y) Translate the shapes position

Methods inherited from class java.lang.Object

finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

centre

protected Point2d centre

radius

protected float radius

Constructor Detail

Circle

public Circle(float x,
              float y,
              float radius)

Construct a circle with the given position and radius

Parameters:

x - the x-coordinate of the centre

y - the y-coordinate of the centre

radius - the radius

Circle

public Circle(Point2d centre,
              float radius)

Construct a circle with the given position and radius

Parameters:

centre - the coordinate of the centre

radius - the radius

Circle

public Circle(Circle c)

Construct a circle with the given circle

Parameters:

c - the circle

Method Detail

isInside

public boolean isInside(Point2d point)

Description copied from interface: Shape

Test whether the point p is inside the shape.

Specified by:

isInside in interface Shape

Parameters:

point - the point

Returns:

true if the point is inside; false otherwise

calculateRegularBoundingBox

public Rectangle calculateRegularBoundingBox()

Description copied from interface: GeometricObject2d

Compute the regular (oriented to the axes) bounding box of the shape.

Specified by:

calculateRegularBoundingBox in interface GeometricObject2d

Returns:

the regular bounding box as [x,y,width,height]

translate

public void translate(float x,
                      float y)

Description copied from interface: GeometricObject2d

Translate the shapes position

Specified by:

translate in interface GeometricObject2d

Parameters:

x - x-translation

y - y-translation

scale

public void scale(float sc)

Description copied from interface: GeometricObject2d

Scale the shape by the given amount about (0,0). Scalefactors between 0 and 1 shrink the shape.

Specified by:

scale in interface GeometricObject2d

Parameters:

sc - the scale factor.

scale

public void scale(Point2d centre,
                  float sc)

Description copied from interface: GeometricObject2d

Scale the shape by the given amount about the given point. Scalefactors between 0 and 1 shrink the shape.

Specified by:

scale in interface GeometricObject2d

Parameters:

centre - the centre of the scaling operation

sc - the scale factor

scaleCentroid

public void scaleCentroid(float sc)

Description copied from interface: GeometricObject2d

Scale the shape about its centroid. Scalefactors between 0 and 1 shrink the shape.

Specified by:

scaleCentroid in interface GeometricObject2d

Parameters:

sc - the scale factor

calculateCentroid

public Point2d calculateCentroid()

Description copied from interface: GeometricObject2d

Calculate the centroid of the shape

Specified by:

calculateCentroid in interface GeometricObject2d

Returns:

the centroid of the shape

calculateArea

public double calculateArea()

Description copied from interface: Shape

Calculate the area of the shape

Specified by:

calculateArea in interface Shape

Returns:

the area of the shape

minX

public double minX()

Specified by:

minX in interface GeometricObject2d

Returns:

the minimum x-ordinate

minY

public double minY()

Specified by:

minY in interface GeometricObject2d

Returns:

the minimum y-ordinate

maxX

public double maxX()

Specified by:

maxX in interface GeometricObject2d

Returns:

the maximum x-ordinate

maxY

public double maxY()

Specified by:

maxY in interface GeometricObject2d

Returns:

the maximum y-ordinate

getWidth

public double getWidth()

Specified by:

getWidth in interface GeometricObject2d

Returns:

the width of the regular bounding box

getHeight

public double getHeight()

Specified by:

getHeight in interface GeometricObject2d

Returns:

the height of the regular bounding box

transform

public Shape transform(Jama.Matrix transform)

Description copied from interface: GeometricObject2d

Apply a 3x3 transform matrix to a copy of the GeometricObject2d and return it

Specified by:

transform in interface GeometricObject2d

Specified by:

transform in interface Shape

Parameters:

transform - 3x3 transform matrix

Returns:

the transformed shape

asPolygon

public Polygon asPolygon()

Description copied from interface: Shape

Convert the shape to a polygon representation

Specified by:

asPolygon in interface Shape

Returns:

a polygon representation of the shape

setX

public void setX(float x)

Set the x-ordinate of the centre of the circle.

Parameters:

x - The x-ordinate

setY

public void setY(float y)

Set the y-ordinate of the centre of the circle.

Parameters:

y - The y-ordinate

setRadius

public void setRadius(float r)

Set the radius of the circle.

Parameters:

r - The radius.

getX

public float getX()

Returns:

The x-ordinate of the centre

getY

public float getY()

Returns:

The y-ordinate of the centre

getRadius

public float getRadius()

Returns:

The radius of the circle

intersectionArea

public double intersectionArea(Shape that)

Description copied from interface: Shape

Calls Polygon.intersectionArea(Shape, int) with 1 step per pixel dimension. Subsequently this function returns the shared whole pixels of this polygon and that.

Specified by:

intersectionArea in interface Shape

Returns:

intersection area

toString

public String toString()

Overrides:

toString in class Object

intersectionArea

public double intersectionArea(Shape that,
                               int nStepsPerDimention)

Description copied from interface: Shape

Return an estimate for the area of the intersection of this polygon and another polygon. For each pixel step 1 is added if the point is inside both polygons. The length of a step in each direction is calculated as follows: max(intersectionWidth,intersectionHeight)/ (nStepsPerDimention) The total number of points inside the intersection of the shames is divided by the number of points read and multiplied by the total area of the intersection.

Specified by:

intersectionArea in interface Shape

Returns:

normalised intersection area

clone

public Circle clone()

Specified by:

clone in interface Shape

Overrides:

clone in class Object

Returns:

a copy of the shape

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

calculatePerimeter

public double calculatePerimeter()

Description copied from interface: Shape

Calculate the perimeter of the shape

Specified by:

calculatePerimeter in interface Shape

Returns:

the perimeter of the shape

minimumBoundingRectangle

public RotatedRectangle minimumBoundingRectangle()

Description copied from interface: Shape

Compute the minimum size rotated bounding rectangle that contains this shape.

Specified by:

minimumBoundingRectangle in interface Shape

Returns:

the minimum bounding box

isConvex

public boolean isConvex()

Description copied from interface: Shape

Test if the shape is convex.

Specified by:

isConvex in interface Shape

Returns:

true if the shape is convex; false if non-convex