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java.awt

Class Polygon

java.lang.Object
- java.awt.Polygon

Implemented Interfaces:: Serializable, Shape

public class Polygon

extends Object

implements Shape, Serializable

This class represents a polygon, a closed, two-dimensional region in a coordinate space. The region is bounded by an arbitrary number of line segments, between (x,y) coordinate vertices. The polygon has even-odd winding, meaning that a point is inside the shape if it crosses the boundary an odd number of times on the way to infinity.

There are some public fields; if you mess with them in an inconsistent manner, it is your own fault when you get NullPointerException, ArrayIndexOutOfBoundsException, or invalid results. Also, this class is not threadsafe.

Since:: 1.0

See Also:: Serialized Form

Field Summary

protected Rectangle

bounds: The bounding box of this polygon.

int

npoints: This total number of endpoints.

int[]

xpoints: The array of X coordinates of endpoints.

int[]

ypoints: The array of Y coordinates of endpoints.

Constructor Summary

Polygon(): Initializes an empty polygon.

Polygon(int[] xpoints, int[] ypoints, int npoints): Create a new polygon with the specified endpoints.

Method Summary

void

addPoint(int x, int y): Adds the specified endpoint to the polygon.

boolean

contains(double x, double y): Tests whether or not the specified point is inside this polygon.

boolean

contains(double x, double y, double w, double h): Test if a high-precision rectangle lies completely in the shape.

boolean

contains(int x, int y): Tests whether or not the specified point is inside this polygon.

boolean

contains(Point p): Tests whether or not the specified point is inside this polygon.

boolean

contains(Point2D p): Tests whether or not the specified point is inside this polygon.

boolean

contains(Rectangle2D r): Test if a high-precision rectangle lies completely in the shape.

Rectangle

getBoundingBox(): Deprecated. use getBounds() instead

Rectangle

getBounds(): Returns the bounding box of this polygon.

Rectangle2D

getBounds2D(): Returns a high-precision bounding box of this polygon.

PathIterator

getPathIterator(AffineTransform transform): Return an iterator along the shape boundary.

PathIterator

getPathIterator(AffineTransform transform, double flatness): Return an iterator along the flattened version of the shape boundary.

boolean

inside(int x, int y): Deprecated. use contains(int,int) instead

boolean

intersects(double x, double y, double w, double h): Test if a high-precision rectangle intersects the shape.

boolean

intersects(Rectangle2D r): Test if a high-precision rectangle intersects the shape.

void

invalidate(): Invalidate or flush all cached data.

void

reset(): Reset the polygon to be empty.

void

translate(int dx, int dy): Translates the polygon by adding the specified values to all X and Y coordinates.

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

bounds

protected Rectangle bounds

The bounding box of this polygon. This is lazily created and cached, so it must be invalidated after changing points.
See Also:
getBounds()

npoints

public int npoints

This total number of endpoints.

xpoints

public int[] xpoints

The array of X coordinates of endpoints. This should not be null.
See Also:
addPoint(int,int)

ypoints

public int[] ypoints

The array of Y coordinates of endpoints. This should not be null.
See Also:
addPoint(int,int)

Constructor Details

Polygon

public Polygon()

Initializes an empty polygon.

Polygon

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

Create a new polygon with the specified endpoints. The arrays are copied, so that future modifications to the parameters do not affect the polygon.
Parameters:
xpoints - the array of X coordinates for this polygon
ypoints - the array of Y coordinates for this polygon
npoints - the total number of endpoints in this polygon
Throws:
NegativeArraySizeException - if npoints is negative
IndexOutOfBoundsException - if npoints exceeds either array
NullPointerException - if xpoints or ypoints is null

Method Details

addPoint

public void addPoint(int x,
 int y)

Adds the specified endpoint to the polygon. This updates the bounding box, if it has been created.
Parameters:
x - the X coordinate of the point to add
y - the Y coordiante of the point to add

contains

public boolean contains(double x,
 double y)

Tests whether or not the specified point is inside this polygon.
Specified by:
contains in interface Shape
Parameters:
x - the X coordinate of the point to test
y - the Y coordinate of the point to test
Returns:
true if the point is inside this polygon
Since:
1.2

contains

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

Test if a high-precision rectangle lies completely in the shape. This is true if all points in the rectangle are in the shape. This implementation is precise.
Specified by:
contains in interface Shape
Parameters:
x - the x coordinate of the rectangle
y - the y coordinate of the rectangle
w - the width of the rectangle, treated as point if negative
h - the height of the rectangle, treated as point if negative
Returns:
true if the rectangle is contained in this shape
Since:
1.2

contains

public boolean contains(int x,
 int y)

Tests whether or not the specified point is inside this polygon.
Parameters:
x - the X coordinate of the point to test
y - the Y coordinate of the point to test
Returns:
true if the point is inside this polygon
Since:
1.1
See Also:
contains(double,double)

contains

public boolean contains(Point p)

Tests whether or not the specified point is inside this polygon.
Parameters:
p - the point to test
Returns:
true if the point is inside this polygon
Throws:
NullPointerException - if p is null
See Also:
contains(double,double)

contains

public boolean contains(Point2D p)

Tests whether or not the specified point is inside this polygon.
Specified by:
contains in interface Shape
Parameters:
p - the point to test
Returns:
true if the point is inside this polygon
Throws:
NullPointerException - if p is null
Since:
1.2
See Also:
contains(double,double)

contains

public boolean contains(Rectangle2D r)

Test if a high-precision rectangle lies completely in the shape. This is true if all points in the rectangle are in the shape. This implementation is precise.
Specified by:
contains in interface Shape
Parameters:
r - the rectangle
Returns:
true if the rectangle is contained in this shape
Throws:
NullPointerException - if r is null
Since:
1.2
See Also:
contains(double,double,double,double)

getBoundingBox

public Rectangle getBoundingBox()

Deprecated. use getBounds() instead
Returns the bounding box of this polygon. This is the smallest rectangle with sides parallel to the X axis that will contain this polygon.
Returns:
the bounding box for this polygon
See Also:
getBounds2D()

getBounds

public Rectangle getBounds()

Returns the bounding box of this polygon. This is the smallest rectangle with sides parallel to the X axis that will contain this polygon.
Specified by:
getBounds in interface Shape
Returns:
the bounding box for this polygon
Since:
1.1
See Also:
getBounds2D()

getBounds2D

public Rectangle2D getBounds2D()

Returns a high-precision bounding box of this polygon. This is the smallest rectangle with sides parallel to the X axis that will contain this polygon.
Specified by:
getBounds2D in interface Shape
Returns:
the bounding box for this polygon
Since:
1.2
See Also:
getBounds()

getPathIterator

public PathIterator getPathIterator(AffineTransform transform)

Return an iterator along the shape boundary. If the optional transform is provided, the iterator is transformed accordingly. Each call returns a new object, independent from others in use. This class is not threadsafe to begin with, so the path iterator is not either.
Specified by:
getPathIterator in interface Shape
Parameters:
transform - an optional transform to apply to the iterator
Returns:
a new iterator over the boundary
Since:
1.2

getPathIterator

public PathIterator getPathIterator(AffineTransform transform,
 double flatness)

Return an iterator along the flattened version of the shape boundary. Since polygons are already flat, the flatness parameter is ignored, and the resulting iterator only has SEG_MOVETO, SEG_LINETO and SEG_CLOSE points. If the optional transform is provided, the iterator is transformed accordingly. Each call returns a new object, independent from others in use. This class is not threadsafe to begin with, so the path iterator is not either.
Specified by:
getPathIterator in interface Shape
Parameters:
transform - an optional transform to apply to the iterator
flatness - the maximum distance for deviation from the real boundary
Returns:
a new iterator over the boundary
Since:
1.2

inside

public boolean inside(int x,
 int y)

Deprecated. use contains(int,int) instead
Tests whether or not the specified point is inside this polygon.
Parameters:
x - the X coordinate of the point to test
y - the Y coordinate of the point to test
Returns:
true if the point is inside this polygon
See Also:
contains(double,double)

intersects

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

Test if a high-precision rectangle intersects the shape. This is true if any point in the rectangle is in the shape. This implementation is precise.
Specified by:
intersects in interface Shape
Parameters:
x - the x coordinate of the rectangle
y - the y coordinate of the rectangle
w - the width of the rectangle, treated as point if negative
h - the height of the rectangle, treated as point if negative
Returns:
true if the rectangle intersects this shape
Since:
1.2

intersects

public boolean intersects(Rectangle2D r)

Test if a high-precision rectangle intersects the shape. This is true if any point in the rectangle is in the shape. This implementation is precise.
Specified by:
intersects in interface Shape
Parameters:
r - the rectangle
Returns:
true if the rectangle intersects this shape
Throws:
NullPointerException - if r is null
Since:
1.2
See Also:
intersects(double,double,double,double)

invalidate

public void invalidate()

Invalidate or flush all cached data. After direct manipulation of the public member fields, this is necessary to avoid inconsistent results in methods like contains.
Since:
1.4
See Also:
getBounds()

reset

public void reset()

Reset the polygon to be empty. The arrays are left alone, to avoid object allocation, but the number of points is set to 0, and all cached data is discarded. If you are discarding a huge number of points, it may be more efficient to just create a new Polygon.
Since:
1.4
See Also:
invalidate()

translate

public void translate(int dx,
 int dy)

Translates the polygon by adding the specified values to all X and Y coordinates. This updates the bounding box, if it has been calculated.
Parameters:
dx - the amount to add to all X coordinates
dy - the amount to add to all Y coordinates
Since:
1.1

Polygon.java -- class representing a polygon Copyright (C) 1999, 2002, 2004, 2005 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.

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