Class Polygon
- java.lang.Object
-
- java.awt.Polygon
- All Implemented Interfaces:
-
Shape
,Serializable
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 (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.
- Since:
- 1.0
- See Also:
-
Shape
, Serialized Form
Field Summary
Modifier and Type | Field | Description |
---|---|---|
protected Rectangle | bounds | The bounds of this |
int | npoints | The total number of points. |
int[] | xpoints | The array of X coordinates. |
int[] | ypoints | The array of Y coordinates. |
Constructor Summary
Constructor | Description |
---|---|
Polygon() | Creates an empty polygon. |
Polygon(int[] xpoints,
int[] ypoints,
int npoints) | Constructs and initializes a |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
void | addPoint(int x,
int y) | Appends the specified coordinates to this |
boolean | contains(double x,
double y) | Tests if the specified coordinates are inside the boundary of the |
boolean | contains(double x,
double y,
double w,
double h) | Tests if the interior of the |
boolean | contains(int x,
int y) | Determines whether the specified coordinates are inside this |
boolean | contains(Point2D p) | Tests if a specified |
boolean | contains(Rectangle2D r) | Tests if the interior of the |
boolean | contains(Point p) | Determines whether the specified |
Rectangle | getBoundingBox() | Deprecated. As of JDK version 1.1, replaced by getBounds() . |
Rectangle | getBounds() | Gets the bounding box of this |
Rectangle2D | getBounds2D() | Returns a high precision and more accurate bounding box of the |
PathIterator | getPathIterator(AffineTransform at) | Returns an iterator object that iterates along the boundary of this |
PathIterator | getPathIterator(AffineTransform at,
double flatness) | Returns an iterator object that iterates along the boundary of the |
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 |
boolean | intersects(Rectangle2D r) | Tests if the interior of the |
void | invalidate() | Invalidates or flushes any internally-cached data that depends on the vertex coordinates of this |
void | reset() | Resets this |
void | translate(int deltaX,
int deltaY) | Translates the vertices of the |
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Field Detail
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 xpoints
or ypoints
. This value can be 0.
- Since:
- 1.0
- See Also:
addPoint(int, int)
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 npoints
is equal to the number of valid points in this Polygon
.
- Since:
- 1.0
- See Also:
addPoint(int, int)
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
.
- Since:
- 1.0
- See Also:
addPoint(int, int)
bounds
protected Rectangle bounds
The bounds of this Polygon
. This value can be null.
- Since:
- 1.0
- See Also:
-
getBoundingBox()
,getBounds()
Constructor Detail
Polygon
public Polygon()
Creates an empty polygon.
- Since:
- 1.0
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 thePolygon
- Throws:
-
NegativeArraySizeException
- if the value ofnpoints
is negative. -
IndexOutOfBoundsException
- ifnpoints
is greater than the length ofxpoints
or the length ofypoints
. -
NullPointerException
- ifxpoints
orypoints
isnull
. - Since:
- 1.0
Method Detail
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.
- Since:
- 1.4
- See Also:
invalidate()
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.
- Since:
- 1.4
- See Also:
getBounds()
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 - Since:
- 1.1
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 - Since:
- 1.0
- See Also:
-
getBounds()
,contains(java.awt.Point)
getBounds
public Rectangle getBounds()
Gets the bounding box of this 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
.
- Specified by:
-
getBounds
in interfaceShape
- Returns:
- a
Rectangle
that defines the bounds of thisPolygon
. - Since:
- 1.1
- See Also:
Shape.getBounds2D()
getBoundingBox
@Deprecated public Rectangle getBoundingBox()
getBounds()
.Returns the bounds of this Polygon
.
- Returns:
- the bounds of this
Polygon
. - Since:
- 1.0
contains
public boolean contains(Point p)
Determines whether the specified Point
is inside this Polygon
.
- Parameters:
-
p
- the specifiedPoint
to be tested - Returns:
-
true
if thePolygon
contains thePoint
;false
otherwise. - Since:
- 1.0
- See Also:
contains(double, double)
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:
-
true
if thisPolygon
contains the specified coordinates(x,y)
;false
otherwise. - Since:
- 1.1
- See Also:
contains(double, double)
inside
@Deprecated public boolean inside(int x, int y)
contains(int, int)
.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:
-
true
if thisPolygon
contains the specified coordinates(x,y)
;false
otherwise. - Since:
- 1.0
- See Also:
contains(double, double)
getBounds2D
public Rectangle2D getBounds2D()
Returns a high precision and more accurate bounding box of the 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)
- Specified by:
-
getBounds2D
in interfaceShape
- Returns:
- an instance of
Rectangle2D
that is a high-precision bounding box of theShape
. - Since:
- 1.2
- See Also:
Shape.getBounds()
contains
public 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.
- Specified by:
-
contains
in interfaceShape
- Parameters:
-
x
- the specified X coordinate to be tested -
y
- the specified Y coordinate to be tested - Returns:
-
true
if the specified coordinates are inside theShape
boundary;false
otherwise. - Since:
- 1.2
contains
public boolean contains(Point2D p)
Tests if a specified Point2D
is inside the boundary of the Shape
, as described by the definition of insideness.
- Specified by:
-
contains
in interfaceShape
- Parameters:
-
p
- the specifiedPoint2D
to be tested - Returns:
-
true
if the specifiedPoint2D
is inside the boundary of theShape
;false
otherwise. - Since:
- 1.2
intersects
public 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. 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:
- there is a high probability that the rectangular area and the
Shape
intersect, but - the calculations to accurately determine this intersection are prohibitively expensive.
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.- Specified by:
-
intersects
in interfaceShape
- Parameters:
-
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 - Returns:
-
true
if the interior of theShape
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. - Since:
- 1.2
- See Also:
Area
intersects
public boolean intersects(Rectangle2D r)
Tests if the interior of the Shape
intersects the interior of a specified Rectangle2D
. The Shape.intersects()
method allows a Shape
implementation to conservatively return true
when:
- there is a high probability that the
Rectangle2D
and theShape
intersect, but - the calculations to accurately determine this intersection are prohibitively expensive.
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. - Specified by:
-
intersects
in interfaceShape
- Parameters:
-
r
- the specifiedRectangle2D
- Returns:
-
true
if the interior of theShape
and the interior of the specifiedRectangle2D
intersect, or are both highly likely to intersect and intersection calculations would be too expensive to perform;false
otherwise. - Since:
- 1.2
- See Also:
Shape.intersects(double, double, double, double)
contains
public boolean contains(double x, double y, double w, double h)
Tests if the interior of the 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:
- the
intersect
method returnstrue
and - the calculations to determine whether or not the
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.- Specified by:
-
contains
in interfaceShape
- Parameters:
-
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 - Returns:
-
true
if the interior of theShape
entirely contains the specified rectangular area;false
otherwise or, if theShape
contains the rectangular area and theintersects
method returnstrue
and the containment calculations would be too expensive to perform. - Since:
- 1.2
- See Also:
-
Area
,Shape.intersects(double, double, double, double)
contains
public boolean contains(Rectangle2D r)
Tests if the interior of the Shape
entirely contains the specified Rectangle2D
. The Shape.contains()
method allows a Shape
implementation to conservatively return false
when:
- the
intersect
method returnstrue
and - the calculations to determine whether or not the
Shape
entirely contains theRectangle2D
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. - Specified by:
-
contains
in interfaceShape
- Parameters:
-
r
- The specifiedRectangle2D
- Returns:
-
true
if the interior of theShape
entirely contains theRectangle2D
;false
otherwise or, if theShape
contains theRectangle2D
and theintersects
method returnstrue
and the containment calculations would be too expensive to perform. - Since:
- 1.2
- See Also:
Shape.contains(double, double, double, double)
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 AffineTransform
can be specified so that the coordinates returned in the iteration are transformed accordingly.
- Specified by:
-
getPathIterator
in interfaceShape
- Parameters:
-
at
- an optionalAffineTransform
to be applied to the coordinates as they are returned in the iteration, ornull
if untransformed coordinates are desired - Returns:
- a
PathIterator
object that provides access to the geometry of thisPolygon
. - Since:
- 1.2
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.
- Specified by:
-
getPathIterator
in interfaceShape
- Parameters:
-
at
- an optionalAffineTransform
to be applied to the coordinates as they are returned in the iteration, ornull
if untransformed coordinates are desired -
flatness
- 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 theflatness
parameter is ignored. - Returns:
- a
PathIterator
object that provides access to theShape
object's geometry. - Since:
- 1.2