public class Polygon extends Objectimplements 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
Determines whether the specified
Point is inside this
Polygon.
|
boolean |
contains(Point2D
Tests if a specified
Point2D is inside the boundary of the
Shape, as described by the
definition of insideness.
|
boolean |
contains(Rectangle2D
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
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
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
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 Rectanglebounds
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 coordinates
ypoints - an array of Y coordinates
npoints - 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.
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 axis
deltaY - the amount to translate along the Y axis
public 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 coordinate
y - the specified Y coordinate
getBounds(),
contains(java.awt.Point)
public RectanglegetBounds()
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
Shape
Rectangle that defines the bounds of this
Polygon.
Shape.getBounds2D()
@Deprecated public RectanglegetBoundingBox()
getBounds().
Polygon.
Polygon.
public boolean contains(Pointp)
Point is inside this
Polygon.
p - the specified
Point to be tested
true 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 tested
y - the specified Y coordinate to be tested
true 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 tested
y - the specified Y coordinate to be tested
true if this
Polygon contains the specified coordinates
(x,y);
false otherwise.
contains(double, double)
public Rectangle2DgetBounds2D()
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.
Shape.getBounds()
public boolean contains(double x,
double y)
Shape, as described by the
definition of insideness.
public boolean contains(Point2Dp)
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 area
y - the Y coordinate of the upper-left corner of the specified rectangular area
w - the width of the specified rectangular area
h - the height of the specified rectangular area
true 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.
Area
public boolean intersects(Rectangle2Dr)
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.
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
Shape
x - the X coordinate of the upper-left corner of the specified rectangular area
y - the Y coordinate of the upper-left corner of the specified rectangular area
w - the width of the specified rectangular area
h - the height of the specified rectangular area
true 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(Rectangle2Dr)
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.
Shape.contains(double, double, double, double)
public PathIteratorgetPathIterator(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 desired
PathIterator object that provides access to the geometry of this
Polygon.
public PathIteratorgetPathIterator(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 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.
PathIterator object that provides access to the
Shape object's geometry.