public class Area extends Object implements Shape, Cloneable
An Area
object stores and manipulates a resolution-independent description of an enclosed area of 2-dimensional space. Area
objects can be transformed and can perform various Constructive Area Geometry (CAG) operations when combined with other Area
objects. The CAG operations include area addition
, subtraction
, intersection
, and exclusive or
. See the linked method documentation for examples of the various operations.
The Area
class implements the Shape
interface and provides full support for all of its hit-testing and path iteration facilities, but an Area
is more specific than a generalized path in a number of ways:
Area
objects constructed from unclosed paths are implicitly closed during construction as if those paths had been filled by the Graphics2D.fill
method. Area
resembles the path from which it was constructed only in that it describes the same enclosed 2-dimensional area, but may use entirely different types and ordering of the path segments to do so. Area
include: Area
from an unclosed (open) Shape
results in a closed outline in the Area
object. Area
from a Shape
which encloses no area (even when "closed") produces an empty Area
. A common example of this issue is that producing an Area
from a line will be empty since the line encloses no area. An empty Area
will iterate no geometry in its PathIterator
objects. Shape
may be split into two (or more) sub-paths each enclosing one of the non-intersecting portions of the original path. Area
may take more path segments to describe the same geometry even when the original outline is simple and obvious. The analysis that the Area
class must perform on the path may not reflect the same concepts of "simple and obvious" as a human being perceives. public Area()
Default constructor which creates an empty area.
public Area(Shape s)
The Area
class creates an area geometry from the specified Shape
object. The geometry is explicitly closed, if the Shape
is not already closed. The fill rule (even-odd or winding) specified by the geometry of the Shape
is used to determine the resulting enclosed area.
s
- the Shape
from which the area is constructedNullPointerException
- if s
is nullpublic void add(Area rhs)
Adds the shape of the specified Area
to the shape of this Area
. The resulting shape of this Area
will include the union of both shapes, or all areas that were contained in either this or the specified Area
.
// Example: Area a1 = new Area([triangle 0,0 => 8,0 => 0,8]); Area a2 = new Area([triangle 0,0 => 8,0 => 8,8]); a1.add(a2); a1(before) + a2 = a1(after) ################ ################ ################ ############## ############## ################ ############ ############ ################ ########## ########## ################ ######## ######## ################ ###### ###### ###### ###### #### #### #### #### ## ## ## ##
rhs
- the Area
to be added to the current shapeNullPointerException
- if rhs
is nullpublic void subtract(Area rhs)
Subtracts the shape of the specified Area
from the shape of this Area
. The resulting shape of this Area
will include areas that were contained only in this Area
and not in the specified Area
.
// Example: Area a1 = new Area([triangle 0,0 => 8,0 => 0,8]); Area a2 = new Area([triangle 0,0 => 8,0 => 8,8]); a1.subtract(a2); a1(before) - a2 = a1(after) ################ ################ ############## ############## ## ############ ############ #### ########## ########## ###### ######## ######## ######## ###### ###### ###### #### #### #### ## ## ##
rhs
- the Area
to be subtracted from the current shapeNullPointerException
- if rhs
is nullpublic void intersect(Area rhs)
Sets the shape of this Area
to the intersection of its current shape and the shape of the specified Area
. The resulting shape of this Area
will include only areas that were contained in both this Area
and also in the specified Area
.
// Example: Area a1 = new Area([triangle 0,0 => 8,0 => 0,8]); Area a2 = new Area([triangle 0,0 => 8,0 => 8,8]); a1.intersect(a2); a1(before) intersect a2 = a1(after) ################ ################ ################ ############## ############## ############ ############ ############ ######## ########## ########## #### ######## ######## ###### ###### #### #### ## ##
rhs
- the Area
to be intersected with this Area
NullPointerException
- if rhs
is nullpublic void exclusiveOr(Area rhs)
Sets the shape of this Area
to be the combined area of its current shape and the shape of the specified Area
, minus their intersection. The resulting shape of this Area
will include only areas that were contained in either this Area
or in the specified Area
, but not in both.
// Example: Area a1 = new Area([triangle 0,0 => 8,0 => 0,8]); Area a2 = new Area([triangle 0,0 => 8,0 => 8,8]); a1.exclusiveOr(a2); a1(before) xor a2 = a1(after) ################ ################ ############## ############## ## ## ############ ############ #### #### ########## ########## ###### ###### ######## ######## ################ ###### ###### ###### ###### #### #### #### #### ## ## ## ##
rhs
- the Area
to be exclusive ORed with this Area
.NullPointerException
- if rhs
is nullpublic void reset()
Removes all of the geometry from this Area
and restores it to an empty area.
public boolean isEmpty()
Tests whether this Area
object encloses any area.
true
if this Area
object represents an empty area; false
otherwise.public boolean isPolygonal()
Tests whether this Area
consists entirely of straight edged polygonal geometry.
true
if the geometry of this Area
consists entirely of line segments; false
otherwise.public boolean isRectangular()
Tests whether this Area
is rectangular in shape.
true
if the geometry of this Area
is rectangular in shape; false
otherwise.public boolean isSingular()
Tests whether this Area
is comprised of a single closed subpath. This method returns true
if the path contains 0 or 1 subpaths, or false
if the path contains more than 1 subpath. The subpaths are counted by the number of SEG_MOVETO
segments that appear in the path.
true
if the Area
is comprised of a single basic geometry; false
otherwise.public Rectangle2D getBounds2D()
Returns a high precision bounding Rectangle2D
that completely encloses this Area
.
The Area class will attempt to return the tightest bounding box possible for the Shape. The bounding box will not be padded to include the control points of curves in the outline of the Shape, but should tightly fit the actual geometry of the outline itself.
getBounds2D
in interface Shape
Rectangle2D
for the Area
.Shape.getBounds()
public Rectangle getBounds()
Returns a bounding Rectangle
that completely encloses this Area
.
The Area class will attempt to return the tightest bounding box possible for the Shape. The bounding box will not be padded to include the control points of curves in the outline of the Shape, but should tightly fit the actual geometry of the outline itself. Since the returned object represents the bounding box with integers, the bounding box can only be as tight as the nearest integer coordinates that encompass the geometry of the Shape.
getBounds
in interface Shape
Rectangle
for the Area
.Shape.getBounds2D()
public Object clone()
Returns an exact copy of this Area
object.
public boolean equals(Area other)
Tests whether the geometries of the two Area
objects are equal. This method will return false if the argument is null.
other
- the Area
to be compared to this Area
true
if the two geometries are equal; false
otherwise.public void transform(AffineTransform t)
Transforms the geometry of this Area
using the specified AffineTransform
. The geometry is transformed in place, which permanently changes the enclosed area defined by this object.
t
- the transformation used to transform the areaNullPointerException
- if t
is nullpublic Area createTransformedArea(AffineTransform t)
Creates a new Area
object that contains the same geometry as this Area
transformed by the specified AffineTransform
. This Area
object is unchanged.
t
- the specified AffineTransform
used to transform the new Area
Area
object representing the transformed geometry.NullPointerException
- if t
is nullpublic 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.
contains
in interface Shape
x
- the specified X coordinate to be testedy
- the specified Y coordinate to be testedtrue
if the specified coordinates are inside the Shape
boundary; false
otherwise.public boolean contains(Point2D p)
Tests if a specified Point2D
is inside the boundary of the Shape
, as described by the definition of insideness.
contains
in interface Shape
p
- the specified Point2D
to be testedtrue
if the specified Point2D
is inside the boundary of the Shape
; false
otherwise.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:
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.Area
, Shape.intersects(double, double, double, double)
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:
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 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:
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.Area
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:
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 PathIterator getPathIterator(AffineTransform at)
Creates a PathIterator
for the outline of this Area
object. This Area
object is unchanged.
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 returns the geometry of the outline of this Area
, one segment at a time.public PathIterator getPathIterator(AffineTransform at, double flatness)
Creates a PathIterator
for the flattened outline of this Area
object. Only uncurved path segments represented by the SEG_MOVETO, SEG_LINETO, and SEG_CLOSE point types are returned by the iterator. This Area
object is unchanged.
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 colinear before a subdivided curve is replaced by a straight line connecting the end pointsPathIterator
object that returns the geometry of the outline of this Area
, one segment at a time.
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