java.awt.geom

Class Arc2D

public abstract class Arc2D extends RectangularShape

This class represents all arcs (segments of an ellipse in 2-D space). The arcs are defined by starting angle and extent (arc length) in degrees, as opposed to radians (like the rest of Java), and can be open, chorded, or wedge shaped. The angles are skewed according to the ellipse, so that 45 degrees always points to the upper right corner (positive x, negative y) of the bounding rectangle. A positive extent draws a counterclockwise arc, and while the angle can be any value, the path iterator only traverses the first 360 degrees. Storage is up to the subclasses.

Since: 1.2

Nested Class Summary
static class	Arc2D.Double This class implements an arc in double precision.
static class	Arc2D.Float This class implements an arc in float precision.

Field Summary
static int	CHORD A closed arc with a single segment connecting the endpoints (a chord).
static int	OPEN An open arc, with no segment connecting the endpoints.
static int	PIE A closed arc with two segments, one from each endpoint, meeting at the center of the ellipse.

Constructor Summary
protected	Arc2D(int type) Create a new arc, with the specified closure type.

Method Summary
boolean	contains(double x, double y) Determines if the arc contains the given point.
boolean	contains(double x, double y, double w, double h) Tests if a given rectangle is contained in the area of the arc.
boolean	contains(Rectangle2D r) Tests if a given rectangle is contained in the area of the arc.
boolean	containsAngle(double a) Tests if the given angle, in degrees, is included in the arc.
abstract double	getAngleExtent() Get the extent angle of the arc in degrees.
abstract double	getAngleStart() Get the starting angle of the arc in degrees.
int	getArcType() Return the closure type of the arc.
Rectangle2D	getBounds2D() Gets the bounds of the arc.
Point2D	getEndPoint() Returns the ending point of the arc.
PathIterator	getPathIterator(AffineTransform at) Returns an iterator over this arc, with an optional transformation.
Point2D	getStartPoint() Returns the starting point of the arc.
boolean	intersects(double x, double y, double w, double h) Tests if a given rectangle intersects the area of the arc.
protected abstract Rectangle2D	makeBounds(double x, double y, double w, double h) Construct a bounding box in a precision appropriate for the subclass.
abstract void	setAngleExtent(double extent) Set the extent, in degrees.
void	setAngles(double x1, double y1, double x2, double y2) Sets the starting and extent angles to those of the given points relative to the center of the arc.
void	setAngles(Point2D p1, Point2D p2) Sets the starting and extent angles to those of the given points relative to the center of the arc.
abstract void	setAngleStart(double start) Set the start, in degrees.
void	setAngleStart(Point2D p) Sets the starting angle to the angle of the given point relative to the center of the arc.
abstract void	setArc(double x, double y, double w, double h, double start, double extent, int type) Set the parameters of the arc.
void	setArc(Point2D p, Dimension2D d, double start, double extent, int type) Set the parameters of the arc.
void	setArc(Rectangle2D r, double start, double extent, int type) Set the parameters of the arc.
void	setArc(Arc2D a) Set the parameters of the arc from the given one.
void	setArcByCenter(double x, double y, double r, double start, double extent, int type) Set the parameters of the arc.
void	setArcByTangent(Point2D p1, Point2D p2, Point2D p3, double r) Sets the parameters of the arc by finding the tangents of two lines, and using the specified radius.
void	setArcType(int type) Set the closure type of this arc.
void	setFrame(double x, double y, double w, double h) Sets the location and bounds of the ellipse of which this arc is a part.

Field Detail

CHORD

public static final int CHORD

A closed arc with a single segment connecting the endpoints (a chord).

OPEN

public static final int OPEN

An open arc, with no segment connecting the endpoints. This type of arc still contains the same points as a chorded version.

PIE

public static final int PIE

A closed arc with two segments, one from each endpoint, meeting at the center of the ellipse.

Constructor Detail

Arc2D

protected Arc2D(int type)

Create a new arc, with the specified closure type.

Parameters: type one of {@link #OPEN}, {@link #CHORD}, or {@link #PIE}.

Throws: IllegalArgumentException if type is invalid

Method Detail

contains

public boolean contains(double x, double y)

Determines if the arc contains the given point. If the bounding box is empty, then this will return false. The area considered 'inside' an arc of type OPEN is the same as the area inside an equivalent filled CHORD-type arc. The area considered 'inside' a CHORD-type arc is the same as the filled area.

Parameters: x the x coordinate to test y the y coordinate to test

Returns: true if the point is inside the arc

contains

public boolean contains(double x, double y, double w, double h)

Tests if a given rectangle is contained in the area of the arc.

Parameters: x the x coordinate of the rectangle y the y coordinate of the rectangle w the width of the rectangle h the height of the rectangle

Returns: true if the arc contains the rectangle

contains

public boolean contains(Rectangle2D r)

Tests if a given rectangle is contained in the area of the arc.

Parameters: r the rectangle

Returns: true if the arc contains the rectangle

containsAngle

public boolean containsAngle(double a)

Tests if the given angle, in degrees, is included in the arc. All angles are normalized to be between 0 and 360 degrees.

Parameters: a the angle to test

Returns: true if it is contained

getAngleExtent

public abstract double getAngleExtent()

Get the extent angle of the arc in degrees.

Returns: the extent angle

See Also: Arc2D

getAngleStart

public abstract double getAngleStart()

Get the starting angle of the arc in degrees.

Returns: the starting angle

See Also: Arc2D

getArcType

public int getArcType()

Return the closure type of the arc.

Returns: the closure type

getBounds2D

public Rectangle2D getBounds2D()

Gets the bounds of the arc. This is much tighter than getBounds, as it takes into consideration the start and end angles, and the center point of a pie wedge, rather than just the overall ellipse.

Returns: the bounds of the arc

See Also: Arc2D

getEndPoint

public Point2D getEndPoint()

Returns the ending point of the arc.

Returns: the end point

getPathIterator

public PathIterator getPathIterator(AffineTransform at)

Returns an iterator over this arc, with an optional transformation. This iterator is threadsafe, so future modifications to the arc do not affect the iteration.

Parameters: at the transformation, or null

Returns: a path iterator

getStartPoint

public Point2D getStartPoint()

Returns the starting point of the arc.

Returns: the start point

intersects

public boolean intersects(double x, double y, double w, double h)

Tests if a given rectangle intersects the area of the arc. For a definition of the 'inside' area, see the contains() method.

Parameters: x the x coordinate of the rectangle y the y coordinate of the rectangle w the width of the rectangle h the height of the rectangle

Returns: true if the two shapes share common points

makeBounds

protected abstract Rectangle2D makeBounds(double x, double y, double w, double h)

Construct a bounding box in a precision appropriate for the subclass.

Parameters: x the x coordinate y the y coordinate w the width h the height

Returns: the rectangle for use in getBounds2D

setAngleExtent

public abstract void setAngleExtent(double extent)

Set the extent, in degrees.

Parameters: extent the new extent angle

setAngles

public void setAngles(double x1, double y1, double x2, double y2)

Sets the starting and extent angles to those of the given points relative to the center of the arc. The arc will be non-empty, and will extend counterclockwise.

Parameters: x1 the first x coordinate y1 the first y coordinate x2 the second x coordinate y2 the second y coordinate

setAngles

public void setAngles(Point2D p1, Point2D p2)

Sets the starting and extent angles to those of the given points relative to the center of the arc. The arc will be non-empty, and will extend counterclockwise.

Parameters: p1 the first point p2 the second point

Throws: NullPointerException if either point is null

setAngleStart

public abstract void setAngleStart(double start)

Set the start, in degrees.

Parameters: start the new start angle

setAngleStart

public void setAngleStart(Point2D p)

Sets the starting angle to the angle of the given point relative to the center of the arc. The extent remains constant; in other words, this rotates the arc.

Parameters: p the new start point

Throws: NullPointerException if p is null

setArc

public abstract void setArc(double x, double y, double w, double h, double start, double extent, int type)

Set the parameters of the arc. The angles are in degrees, and a positive extent sweeps counterclockwise (from the positive x-axis to the negative y-axis).

Parameters: x the new x coordinate of the upper left of the bounding box y the new y coordinate of the upper left of the bounding box w the new width of the bounding box h the new height of the bounding box start the start angle, in degrees extent the arc extent, in degrees type one of {@link #OPEN}, {@link #CHORD}, or {@link #PIE}

Throws: IllegalArgumentException if type is invalid

setArc

public void setArc(Point2D p, Dimension2D d, double start, double extent, int type)

Set the parameters of the arc. The angles are in degrees, and a positive extent sweeps counterclockwise (from the positive x-axis to the negative y-axis).

Parameters: p the upper left point of the bounding box d the dimensions of the bounding box start the start angle, in degrees extent the arc extent, in degrees type one of {@link #OPEN}, {@link #CHORD}, or {@link #PIE}

Throws: IllegalArgumentException if type is invalid NullPointerException if p or d is null

setArc

public void setArc(Rectangle2D r, double start, double extent, int type)

Set the parameters of the arc. The angles are in degrees, and a positive extent sweeps counterclockwise (from the positive x-axis to the negative y-axis).

Parameters: r the new bounding box start the start angle, in degrees extent the arc extent, in degrees type one of {@link #OPEN}, {@link #CHORD}, or {@link #PIE}

Throws: IllegalArgumentException if type is invalid NullPointerException if r is null

setArc

public void setArc(Arc2D a)

Set the parameters of the arc from the given one.

Parameters: a the arc to copy

Throws: NullPointerException if a is null

setArcByCenter

public void setArcByCenter(double x, double y, double r, double start, double extent, int type)

Set the parameters of the arc. The angles are in degrees, and a positive extent sweeps counterclockwise (from the positive x-axis to the negative y-axis). This controls the center point and radius, so the arc will be circular.

Parameters: x the x coordinate of the center of the circle y the y coordinate of the center of the circle r the radius of the circle start the start angle, in degrees extent the arc extent, in degrees type one of {@link #OPEN}, {@link #CHORD}, or {@link #PIE}

Throws: IllegalArgumentException if type is invalid

setArcByTangent

public void setArcByTangent(Point2D p1, Point2D p2, Point2D p3, double r)

Sets the parameters of the arc by finding the tangents of two lines, and using the specified radius. The arc will be circular, will begin on the tangent point of the line extending from p1 to p2, and will end on the tangent point of the line extending from p2 to p3. XXX What happens if the points are colinear, or the radius negative?

Parameters: p1 the first point p2 the tangent line intersection point p3 the third point r the radius of the arc

Throws: NullPointerException if any point is null

setArcType

public void setArcType(int type)

Set the closure type of this arc.

Parameters: type one of {@link #OPEN}, {@link #CHORD}, or {@link #PIE}

Throws: IllegalArgumentException if type is invalid

setFrame

public void setFrame(double x, double y, double w, double h)

Sets the location and bounds of the ellipse of which this arc is a part.

Parameters: x the new x coordinate y the new y coordinate w the new width h the new height

See Also: Arc2D