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.Shape,
Serialized Form| Modifier and Type | Field and 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 and Description |
|---|
Polygon()
Creates an empty polygon.
|
Polygon(int[] xpoints,
int[] ypoints,
int npoints)
Constructs and initializes a
Polygon from the specified
parameters. |
| Modifier and Type | Method and Description |
|---|---|
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, as described by the
definition of insideness. |
boolean |
contains(double x,
double y,
double w,
double h)
Tests if the interior of the
Shape entirely contains
the specified rectangular area. |
boolean |
contains(int x,
int y)
Determines whether the specified coordinates are inside 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 the Shape, as described by the
definition of insideness. |
boolean |
contains(Rectangle2D r)
Tests if the interior of the
Shape 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 a high precision and more accurate bounding box of
the
Shape than the getBounds method. |
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 the
Shape intersects the
interior of a specified rectangular area. |
boolean |
intersects(Rectangle2D r)
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(int deltaX,
int deltaY)
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 NULL.addPoint(int, int)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.addPoint(int, int)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.addPoint(int, int)protected Rectangle bounds
Polygon.
This value can be null.getBoundingBox(),
getBounds()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
PolygonNegativeArraySizeException - 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.invalidate()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.getBounds()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 coordinategetBounds(),
contains(java.awt.Point)public 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.getBounds in interface ShapeRectangle that defines the bounds of this
Polygon.Shape.getBounds2D()@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.contains(double, double)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.contains(double, double)@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.contains(double, double)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 ShapeRectangle2D that is a
high-precision bounding box of the Shape.Shape.getBounds()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 Shapex - 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.Areapublic 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 Shaper - the specified Rectangle2Dtrue 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.Shape.intersects(double, double, double, double)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 Shapex - 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.Area,
Shape.intersects(double, double, double, double)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 Shaper - The specified Rectangle2Dtrue 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.Shape.contains(double, double, double, double)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 Shapeat - 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 Shapeat - 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 colinear 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. Submit a bug or feature
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