java.awt
Class Polygon

java.lang.Object
  |
  +--java.awt.Polygon

public class Polygon

extends Object

implements Shape, Serializable

The Polygon class encapsulates a description of a closed, two-dimensional region within a coordinate space. This region is bounded by an arbitrary number of line segments, each of which is one side of the polygon. Internally, a polygon comprises of a list of (x, y) coordinate pairs, where each pair defines a vertex of the polygon, and two successive pairs are the endpoints of a line that is a side of the polygon. The first and final pairs of (x, y) points are joined by a line segment that closes the polygon.

Since:

JDK1.0

See Also:

Serialized Form

Field Summary

protected Rectangle	bounds Bounds of the polygon.
int	npoints The total number of points.
int[]	xpoints The array of x coordinates.
int[]	ypoints The array of y coordinates.

Constructor Summary

Polygon()
Creates an empty polygon.

Polygon(int[] xpoints, int[] ypoints, int npoints)
Constructs and initializes a Polygon from the specified parameters.

Method Summary

void	addPoint(int x, int y) Appends the specified coordinates to this Polygon.
boolean	contains(double x, double y) Tests if the specified coordinates are inside the boundary of the Shape.
boolean	contains(double x, double y, double w, double h) Tests if the interior of this Polygon entirely contains the specified set of rectangular coordinates.
boolean	contains(int x, int y) Determines whether the specified coordinates are contained in this Polygon.
boolean	contains(Point p) Determines whether the specified Point is inside this Polygon.
boolean	contains(Point2D p) Tests if a specified Point2D is inside the boundary of this Polygon.
boolean	contains(Rectangle2D r) Tests if the interior of this Polygon entirely contains the specified Rectangle2D.
Rectangle	getBoundingBox() Deprecated. As of JDK version 1.1, replaced by getBounds().
Rectangle	getBounds() Gets the bounding box of this Polygon.
Rectangle2D	getBounds2D() Returns the high precision bounding box of the Shape.
PathIterator	getPathIterator(AffineTransform at) Returns an iterator object that iterates along the boundary of this Polygon and provides access to the geometry of the outline of this Polygon.
PathIterator	getPathIterator(AffineTransform at, double flatness) Returns an iterator object that iterates along the boundary of the Shape and provides access to the geometry of the outline of the Shape.
boolean	inside(int x, int y) Deprecated. As of JDK version 1.1, replaced by contains(int, int).
boolean	intersects(double x, double y, double w, double h) Tests if the interior of this Polygon intersects the interior of a specified set of rectangular coordinates.
boolean	intersects(Rectangle2D r) Tests if the interior of this Polygon intersects the interior of a specified Rectangle2D.
void	translate(int deltaX, int deltaY) Translates the vertices of the Polygon by deltaX along the x axis and by deltaY along the y axis.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

npoints

public int npoints

The total number of points. This value can be NULL.

See Also:

addPoint(int, int)

xpoints

public int[] xpoints

The array of x coordinates.

See Also:

addPoint(int, int)

ypoints

public int[] ypoints

The array of y coordinates.

See Also:

addPoint(int, int)

bounds

protected Rectangle bounds

Bounds of the polygon. This value can be NULL. Please see the javadoc comments getBounds().

See Also:

getBoundingBox(), getBounds()

Constructor Detail

Polygon

public Polygon()

Creates an empty polygon.

Polygon

public Polygon(int[] xpoints,
               int[] ypoints,
               int npoints)

Constructs and initializes a Polygon from the specified parameters.

Parameters:

xpoints - an array of x coordinates

ypoints - an array of y coordinates

npoints - the total number of points in the Polygon

Throws:

NegativeArraySizeException - if the value of npoints is negative.

Method Detail

translate

public void translate(int deltaX,
                      int deltaY)

Translates the vertices of the Polygon by deltaX along the x axis and by deltaY along the y axis.

Parameters:

deltaX - the amount to translate along the x axis

deltaY - the amount to translate along the y axis

Since:

JDK1.1

addPoint

public void addPoint(int x,
                     int y)

Appends the specified coordinates to this Polygon.

If an operation that calculates the bounding box of this Polygon has already been performed, such as getBounds or contains, then this method updates the bounding box.

Parameters:

x, y - the specified coordinates

See Also:

getBounds(), contains(java.awt.Point)

getBounds

public Rectangle getBounds()

Gets the bounding box of this Polygon. The bounding box is the smallest Rectangle whose sides are parallel to the x and y axes of the coordinate space, and can completely contain the Polygon.

Specified by:

getBounds in interface Shape

Returns:

a Rectangle that defines the bounds of this Polygon.

Since:

JDK1.1

getBoundingBox

public Rectangle getBoundingBox()

Deprecated. As of JDK version 1.1, replaced by getBounds().

contains

public boolean contains(Point p)

Determines whether the specified Point is inside this Polygon. Uses an even-odd insideness rule (also known as an alternating rule).

Parameters:

p - the specified Point to be tested

Returns:

true if the Polygon contains the Point; false otherwise.

contains

public boolean contains(int x,
                        int y)

Determines whether the specified coordinates are contained in this Polygon.

(The contains method is based on code by Hanpeter van Vliet [hvvliet@inter.nl.net].)

Parameters:

x, y - the specified coordinates to be tested

Returns:

true if this Polygon contains the specified coordinates, (x, y); false otherwise.

Since:

JDK1.1

inside

public boolean inside(int x,
                      int y)

Deprecated. As of JDK version 1.1, replaced by contains(int, int).

getBounds2D

public Rectangle2D getBounds2D()

Returns the high precision bounding box of the Shape.

Specified by:

getBounds2D in interface Shape

Returns:

a Rectangle2D that precisely bounds the Shape.

contains

public boolean contains(double x,
                        double y)

Tests if the specified coordinates are inside the boundary of the Shape.

Specified by:

contains in interface Shape

Parameters:

x, y - the specified coordinates

Returns:

true if the Shape contains the specified coordinates; false otherwise.

contains

public boolean contains(Point2D p)

Tests if a specified Point2D is inside the boundary of this Polygon.

Specified by:

contains in interface Shape

Parameters:

p - a specified Point2D

Returns:

true if this Polygon contains the specified Point2D; false otherwise.

intersects

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

Tests if the interior of this Polygon intersects the interior of a specified set of rectangular coordinates.

Specified by:

intersects in interface Shape

Parameters:

x, y - the coordinates of the specified rectangular shape's top-left corner

w - the width of the specified rectangular shape

h - the height of the specified rectangular shape

Returns:

true if the interior of this Polygon and the interior of the specified set of rectangular coordinates intersect each other; false otherwise.

intersects

public boolean intersects(Rectangle2D r)

Tests if the interior of this Polygon intersects the interior of a specified Rectangle2D.

Specified by:

intersects in interface Shape

Parameters:

r - a specified Rectangle2D

Returns:

true if this Polygon and the interior of the specified Rectangle2D intersect each other; false otherwise.

contains

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

Tests if the interior of this Polygon entirely contains the specified set of rectangular coordinates.

Specified by:

contains in interface Shape

Parameters:

x, y - the coordinate of the top-left corner of the specified set of rectangular coordinates

w - the width of the set of rectangular coordinates

h - the height of the set of rectangular coordinates

Returns:

true if this Polygon entirely contains the specified set of rectangular coordinates; false otherwise.

contains

public boolean contains(Rectangle2D r)

Tests if the interior of this Polygon entirely contains the specified Rectangle2D.

Specified by:

contains in interface Shape

Parameters:

r - the specified Rectangle2D

Returns:

true if this Polygon entirely contains the specified Rectangle2D; false otherwise.

getPathIterator

public PathIterator getPathIterator(AffineTransform at)

Returns an iterator object that iterates along the boundary of this Polygon and provides access to the geometry of the outline of this Polygon. An optional AffineTransform can be specified so that the coordinates returned in the iteration are transformed accordingly.

Specified by:

getPathIterator in interface Shape

Parameters:

at - an optional AffineTransform to be applied to the coordinates as they are returned in the iteration, or null if untransformed coordinates are desired

Returns:

a PathIterator object that provides access to the geometry of this Polygon.

getPathIterator

public PathIterator getPathIterator(AffineTransform at,
                                    double flatness)

Returns an iterator object that iterates along the boundary of the Shape and provides access to the geometry of the outline of the Shape. Only SEG_MOVETO, SEG_LINETO, and SEG_CLOSE point types are returned by the iterator. Since polygons are already flat, the flatness parameter is ignored. An optional AffineTransform can be specified in which case the coordinates returned in the iteration are transformed accordingly.

Specified by:

getPathIterator in interface Shape

Parameters:

at - an optional AffineTransform to be applied to the coordinates as they are returned in the iteration, or null if untransformed coordinates are desired

flatness - the maximum amount that the control points for a given curve can vary from colinear before a subdivided curve is replaced by a straight line connecting the endpoints. Since polygons are already flat the flatness parameter is ignored.

Returns:

a PathIterator object that provides access to the Shape object's geometry.