java.awt
class Polygon

java.lang.Object java.awt.Polygon

All Implemented Interfaces:

Shape, Serializable

Most common way to construct:

Polygon p = new Polygon();

Based on 211 examples

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 {@code (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 {@code (x,y)} points are joined by a line segment that closes the polygon. This Polygon is defined with an even-odd winding rule. See {@link java.awt.geom.PathIterator#WIND_EVEN_ODD WIND_EVEN_ODD} for a definition of the even-odd winding rule. This class's hit-testing methods, which include the contains, intersects and inside methods, use the insideness definition described in the {@link Shape} class comments.

bounds

protected Rectangle bounds

The bounds of this {@code Polygon}. This value can be null.

npoints

public int npoints

The total number of points. The value of npoints represents the number of valid points in this Polygon and might be less than the number of elements in {@link #xpoints xpoints} or {@link #ypoints ypoints}. This value can be NULL.

xpoints

public int[] xpoints

The array of X coordinates. The number of elements in this array might be more than the number of X coordinates in this Polygon. The extra elements allow new points to be added to this Polygon without re-creating this array. The value of {@link #npoints npoints} is equal to the number of valid points in this Polygon.

ypoints

public int[] ypoints

The array of Y coordinates. The number of elements in this array might be more than the number of Y coordinates in this Polygon. The extra elements allow new points to be added to this Polygon without re-creating this array. The value of npoints is equal to the number of valid points in this Polygon.

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

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 - the specified X coordinate

y - the specified Y coordinate

contains

public boolean contains(double x,
                        double y)

{@inheritDoc}

Parameters:

x

y

contains

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

{@inheritDoc}

Parameters:

x

y

w

h

contains

public boolean contains(int x,
                        int y)

Determines whether the specified coordinates are inside this Polygon.

Parameters:

x - the specified X coordinate to be tested

y - the specified Y coordinate to be tested

Returns:

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

contains

public boolean contains(Point p)

Determines whether the specified {@link Point} is inside this Polygon.

Parameters:

p - the specified Point to be tested

Returns:

true if the Polygon contains the Point; false otherwise.

contains

public boolean contains(Point2D p)

{@inheritDoc}

Parameters:

p

contains

public boolean contains(Rectangle2D r)

{@inheritDoc}

Parameters:

r

getBoundingBox

public Rectangle getBoundingBox()

Returns the bounds of this Polygon.

Returns:

the bounds of this Polygon.

getBounds

public Rectangle getBounds()

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

Returns:

a Rectangle that defines the bounds of this Polygon.

getBounds2D

public Rectangle2D getBounds2D()

{@inheritDoc}

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 {@link AffineTransform} can be specified so that the coordinates returned in the iteration are transformed accordingly.

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 {@link 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.

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.

inside

public boolean inside(int x,
                      int y)

Determines whether the specified coordinates are contained in this Polygon.

Parameters:

x - the specified X coordinate to be tested

y - the specified Y coordinate to be tested

Returns:

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

intersects

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

{@inheritDoc}

Parameters:

x

y

w

h

intersects

public boolean intersects(Rectangle2D r)

{@inheritDoc}

Parameters:

r

invalidate

public void invalidate()

Invalidates or flushes any internally-cached data that depends on the vertex coordinates of this Polygon. This method should be called after any direct manipulation of the coordinates in the xpoints or ypoints arrays to avoid inconsistent results from methods such as getBounds or contains that might cache data from earlier computations relating to the vertex coordinates.

reset

public void reset()

Resets this Polygon object to an empty polygon. The coordinate arrays and the data in them are left untouched but the number of points is reset to zero to mark the old vertex data as invalid and to start accumulating new vertex data at the beginning. All internally-cached data relating to the old vertices are discarded. Note that since the coordinate arrays from before the reset are reused, creating a new empty Polygon might be more memory efficient than resetting the current one if the number of vertices in the new polygon data is significantly smaller than the number of vertices in the data from before the reset.

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