public class Area extends Object implements Shape, Cloneable
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.
| Constructor and Description |
|---|
Area()
Default constructor which creates an empty area.
|
Area(Shape s)
The
Area class creates an area geometry from the
specified Shape object. |
| Modifier and Type | Method and Description |
|---|---|
void |
add(Area rhs)
Adds the shape of the specified
Area to the
shape of this Area. |
Object |
clone()
Returns an exact copy of this
Area object. |
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(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. |
Area |
createTransformedArea(AffineTransform t)
Creates a new
Area object that contains the same
geometry as this Area transformed by the specified
AffineTransform. |
boolean |
equals(Area other)
Tests whether the geometries of the two
Area objects
are equal. |
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. |
Rectangle |
getBounds()
Returns a bounding
Rectangle that completely encloses
this Area. |
Rectangle2D |
getBounds2D()
Returns a high precision bounding
Rectangle2D that
completely encloses this Area. |
PathIterator |
getPathIterator(AffineTransform at)
Creates a
PathIterator for the outline of this
Area object. |
PathIterator |
getPathIterator(AffineTransform at,
double flatness)
Creates a
PathIterator for the flattened outline of
this Area object. |
void |
intersect(Area rhs)
Sets the shape of this
Area to the intersection of
its current shape and the shape of the specified Area. |
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. |
boolean |
isEmpty()
Tests whether this
Area object encloses any area. |
boolean |
isPolygonal()
Tests whether this
Area consists entirely of
straight edged polygonal geometry. |
boolean |
isRectangular()
Tests whether this
Area is rectangular in shape. |
boolean |
isSingular()
Tests whether this
Area is comprised of a single
closed subpath. |
void |
reset()
Removes all of the geometry from this
Area and
restores it to an empty area. |
void |
subtract(Area rhs)
Subtracts the shape of the specified
Area from the
shape of this Area. |
void |
transform(AffineTransform t)
Transforms the geometry of this
Area using the specified
AffineTransform. |
public Area()
public Area(Shape s)
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)
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)
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)
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
AreaNullPointerException - if rhs is nullpublic void exclusiveOr(Area rhs)
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()
Area and
restores it to an empty area.public boolean isEmpty()
Area object encloses any area.true if this Area object
represents an empty area; false otherwise.public boolean isPolygonal()
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()
Area is rectangular in shape.true if the geometry of this
Area is rectangular in shape; false
otherwise.public boolean isSingular()
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()
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 ShapeRectangle2D for the
Area.Shape.getBounds()public Rectangle getBounds()
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 ShapeRectangle for the
Area.Shape.getBounds2D()public Object clone()
Area object.public boolean equals(Area other)
Area objects
are equal.
This method will return false if the argument is null.other - the Area to be compared to this
Areatrue if the two geometries are equal;
false otherwise.public void transform(AffineTransform t)
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)
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 AreaArea object representing the transformed
geometry.NullPointerException - if t is nullpublic 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 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 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 PathIterator getPathIterator(AffineTransform at)
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 returns the
geometry of the outline of this Area, one
segment at a time.public PathIterator getPathIterator(AffineTransform at, double flatness)
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 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 end pointsPathIterator object that returns the
geometry of the outline of this Area, one segment
at a time. Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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