Shape
, Serializable
public class Polygon extends Object implements Shape, Serializable
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. This Polygon
is defined with an even-odd winding rule. See 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 Shape
class comments.Modifier and Type | Field | Description |
---|---|---|
protected Rectangle |
bounds |
The bounds of this Polygon . |
int |
npoints |
The total number of points. |
int[] |
xpoints |
The array of X coordinates. |
int[] |
ypoints |
The array of Y coordinates. |
Constructor | Description |
---|---|
Polygon() |
Creates an empty polygon. |
Polygon |
Constructs and initializes a Polygon from the specified parameters. |
Modifier and Type | Method | Description |
---|---|---|
void |
addPoint |
Appends the specified coordinates to this Polygon . |
boolean |
contains |
Tests if the specified coordinates are inside the boundary of the Shape , as described by the definition of insideness. |
boolean |
contains |
Tests if the interior of the Shape entirely contains the specified rectangular area. |
boolean |
contains |
Determines whether the specified coordinates are inside this Polygon . |
boolean |
contains |
Tests if a specified Point2D is inside the boundary of the Shape , as described by the definition of insideness. |
boolean |
contains |
Tests if the interior of the Shape entirely contains the specified Rectangle2D . |
boolean |
contains |
Determines whether the specified Point is inside this Polygon . |
Rectangle |
getBoundingBox() |
Deprecated. |
Rectangle |
getBounds() |
Gets the bounding box of this Polygon . |
Rectangle2D |
getBounds2D() |
Returns a high precision and more accurate bounding box of the Shape than the getBounds method. |
PathIterator |
getPathIterator |
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 |
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 |
Deprecated. As of JDK version 1.1, replaced by contains(int, int) . |
boolean |
intersects |
Tests if the interior of the Shape intersects the interior of a specified rectangular area. |
boolean |
intersects |
Tests if the interior of the Shape intersects the interior of a specified Rectangle2D . |
void |
invalidate() |
Invalidates or flushes any internally-cached data that depends on the vertex coordinates of this Polygon . |
void |
reset() |
Resets this Polygon object to an empty polygon. |
void |
translate |
Translates the vertices of the Polygon by deltaX along the x axis and by deltaY along the y axis. |
public int npoints
npoints
represents the number of valid points in this Polygon
and might be less than the number of elements in xpoints
or ypoints
. This value can be 0.public int[] xpoints
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
.public int[] ypoints
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
.protected Rectangle bounds
Polygon
. This value can be null.public Polygon()
public Polygon(int[] xpoints, int[] ypoints, int npoints)
Polygon
from the specified parameters.xpoints
- an array of X coordinatesypoints
- an array of Y coordinatesnpoints
- the total number of points in the Polygon
NegativeArraySizeException
- if the value of npoints
is negative.IndexOutOfBoundsException
- if npoints
is greater than the length of xpoints
or the length of ypoints
.NullPointerException
- if xpoints
or ypoints
is null
.public void reset()
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.public void invalidate()
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.public void translate(int deltaX, int deltaY)
Polygon
by deltaX
along the x axis and by deltaY
along the y axis.deltaX
- the amount to translate along the X axisdeltaY
- the amount to translate along the Y axispublic void addPoint(int x, int y)
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.
x
- the specified X coordinatey
- the specified Y coordinatepublic Rectangle getBounds()
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
.@Deprecated public Rectangle getBoundingBox()
getBounds()
.Polygon
.Polygon
.public boolean contains(Point p)
Point
is inside this Polygon
.p
- the specified Point
to be testedtrue
if the Polygon
contains the Point
; false
otherwise.public boolean contains(int x, int y)
Polygon
.x
- the specified X coordinate to be testedy
- the specified Y coordinate to be testedtrue
if this Polygon
contains the specified coordinates (x,y)
; false
otherwise.@Deprecated public boolean inside(int x, int y)
contains(int, int)
.Polygon
.x
- the specified X coordinate to be testedy
- the specified Y coordinate to be testedtrue
if this Polygon
contains the specified coordinates (x,y)
; false
otherwise.public Rectangle2D getBounds2D()
Shape
than the getBounds
method. Note that there is no guarantee that the returned Rectangle2D
is the smallest bounding box that encloses the Shape
, only that the Shape
lies entirely within the indicated Rectangle2D
. The bounding box returned by this method is usually tighter than that returned by the getBounds
method and never fails due to overflow problems since the return value can be an instance of the Rectangle2D
that uses double precision values to store the dimensions. Note that the definition of insideness can lead to situations where points on the defining outline of the shape
may not be considered contained in the returned bounds
object, but only in cases where those points are also not considered contained in the original shape
.
If a point
is inside the shape
according to the contains(point)
method, then it must be inside the returned Rectangle2D
bounds object according to the contains(point)
method of the bounds
. Specifically:
shape.contains(p)
requires bounds.contains(p)
If a point
is not inside the shape
, then it might still be contained in the bounds
object:
bounds.contains(p)
does not imply shape.contains(p)
getBounds2D
in interface Shape
Rectangle2D
that is a high-precision bounding box of the Shape
.public boolean contains(double x, double y)
Shape
, as described by the definition of insideness.public boolean contains(Point2D p)
Point2D
is inside the boundary of the Shape
, as described by the definition of insideness.public boolean intersects(double x, double y, double w, double h)
Shape
intersects the interior of a specified rectangular area. The rectangular area is considered to intersect the Shape
if any point is contained in both the interior of the Shape
and the specified rectangular area. The Shape.intersects()
method allows a Shape
implementation to conservatively return true
when:
Shape
intersect, but Shapes
this method might return true
even though the rectangular area does not intersect the Shape
. The Area
class performs more accurate computations of geometric intersection than most Shape
objects and therefore can be used if a more precise answer is required.intersects
in interface Shape
x
- the X coordinate of the upper-left corner of the specified rectangular areay
- the Y coordinate of the upper-left corner of the specified rectangular areaw
- the width of the specified rectangular areah
- the height of the specified rectangular areatrue
if the interior of the Shape
and the interior of the rectangular area intersect, or are both highly likely to intersect and intersection calculations would be too expensive to perform; false
otherwise.public boolean intersects(Rectangle2D r)
Shape
intersects the interior of a specified Rectangle2D
. The Shape.intersects()
method allows a Shape
implementation to conservatively return true
when: Rectangle2D
and the Shape
intersect, but Shapes
this method might return true
even though the Rectangle2D
does not intersect the Shape
. The Area
class performs more accurate computations of geometric intersection than most Shape
objects and therefore can be used if a more precise answer is required.intersects
in interface Shape
r
- the specified Rectangle2D
true
if the interior of the Shape
and the interior of the specified Rectangle2D
intersect, or are both highly likely to intersect and intersection calculations would be too expensive to perform; false
otherwise.public boolean contains(double x, double y, double w, double h)
Shape
entirely contains the specified rectangular area. All coordinates that lie inside the rectangular area must lie within the Shape
for the entire rectangular area to be considered contained within the Shape
. The Shape.contains()
method allows a Shape
implementation to conservatively return false
when:
intersect
method returns true
and Shape
entirely contains the rectangular area are prohibitively expensive. Shapes
this method might return false
even though the Shape
contains the rectangular area. The Area
class performs more accurate geometric computations than most Shape
objects and therefore can be used if a more precise answer is required.contains
in interface Shape
x
- the X coordinate of the upper-left corner of the specified rectangular areay
- the Y coordinate of the upper-left corner of the specified rectangular areaw
- the width of the specified rectangular areah
- the height of the specified rectangular areatrue
if the interior of the Shape
entirely contains the specified rectangular area; false
otherwise or, if the Shape
contains the rectangular area and the intersects
method returns true
and the containment calculations would be too expensive to perform.public boolean contains(Rectangle2D r)
Shape
entirely contains the specified Rectangle2D
. The Shape.contains()
method allows a Shape
implementation to conservatively return false
when: intersect
method returns true
and Shape
entirely contains the Rectangle2D
are prohibitively expensive. Shapes
this method might return false
even though the Shape
contains the Rectangle2D
. The Area
class performs more accurate geometric computations than most Shape
objects and therefore can be used if a more precise answer is required.contains
in interface Shape
r
- The specified Rectangle2D
true
if the interior of the Shape
entirely contains the Rectangle2D
; false
otherwise or, if the Shape
contains the Rectangle2D
and the intersects
method returns true
and the containment calculations would be too expensive to perform.public PathIterator getPathIterator(AffineTransform at)
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.getPathIterator
in interface Shape
at
- an optional AffineTransform
to be applied to the coordinates as they are returned in the iteration, or null
if untransformed coordinates are desiredPathIterator
object that provides access to the geometry of this Polygon
.public PathIterator getPathIterator(AffineTransform at, double flatness)
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.getPathIterator
in interface Shape
at
- an optional AffineTransform
to be applied to the coordinates as they are returned in the iteration, or null
if untransformed coordinates are desiredflatness
- the maximum amount that the control points for a given curve can vary from collinear before a subdivided curve is replaced by a straight line connecting the endpoints. Since polygons are already flat the flatness
parameter is ignored.PathIterator
object that provides access to the Shape
object's geometry.
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https://docs.oracle.com/en/java/javase/21/docs/api/java.desktop/java/awt/Polygon.html
getBounds()
.