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java.awt.geom
Class Area
java.lang.Object
java.awt.geom.Area
-
All Implemented Interfaces:
-
Shape
,
Cloneable
-
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 is a device-independent specification of an arbitrarily-shaped area. The Area object is defined as an object that performs certain binary CAG (Constructive Area Geometry) operations on other area-enclosing geometries, such as rectangles, ellipses, and polygons. The CAG operations are Add(union), Subtract, Intersect, and ExclusiveOR. For example, an Area can be made up of the area of a rectangle minus the area of an ellipse.
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:
-
Only closed paths and sub-paths are stored. Area objects constructed from unclosed paths are implicitly closed during construction as if those paths had been filled by the Graphics2D.fill method.
-
The interiors of the individual stored sub-paths are all non-empty and non-overlapping. Paths are decomposed during construction into separate component non-overlapping parts, empty pieces of the path are discarded, and then these non-empty and non-overlapping properties are maintained through all subsequent CAG operations. Outlines of different component sub-paths may touch each other, as long as they do not cross so that their enclosed areas overlap.
-
The geometry of the path describing the outline of the 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.
Interesting issues which are not always obvious when using the Area include:
-
Creating an Area from an unclosed (open) Shape results in a closed outline in the Area object.
-
Creating an 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.
-
A self-intersecting Shape may be split into two (or more) sub-paths each enclosing one of the non-intersecting portions of the original path.
-
An 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.
-
Since:
-
1.2
Constructor Summary
|
Area
()
Default constructor which creates an empty area. |
Area
(
Shape
s)
The Area class creates an area geometry from the specified
Shape
object. |
Method Summary
|
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
a specifed point lies
inside the boundary of
the Shape.
this Area object.
|
boolean |
contains
(double x, double y, double w, double h)
Tests
if
whether or not
the interior of
the Shape entirely
this Area object completely
contains the specified rectangular area. |
boolean |
contains
(
Point2D
Tests if a specified
Point2D
|
boolean |
contains
(
Rectangle2D
Tests
if
whether or not
the interior of
the Shape entirely
this Area object completely
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
whether
the interior of
the Shape
this Area object
intersects the interior of
a
the
specified rectangular area. |
boolean |
intersects
(
Rectangle2D
Tests
if
whether
the interior of
the Shape
this Area object
intersects the interior of
a
the
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
. |
Area
public Area()
-
Default constructor which creates an empty area.
-
Since:
-
1.2
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.
-
Parameters:
-
s - the Shape from which the area is constructed
-
Throws:
-
NullPointerException
- if s is null
-
Since:
-
1.2
add
public 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)
################ ################ ################
############## ############## ################
############ ############ ################
########## ########## ################
######## ######## ################
###### ###### ###### ######
#### #### #### ####
## ## ## ##
Addition is achieved through union.
-
-
-
Parameters:
-
rhs - the Area to be added to the current shape
-
Throws:
-
NullPointerException
- if rhs is null
-
Since:
-
1.2
subtract
public 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)
################ ################
############## ############## ##
############ ############ ####
########## ########## ######
######## ######## ########
###### ###### ######
#### #### ####
## ## ##
-
-
-
Parameters:
-
rhs - the Area to be subtracted from the current shape
-
Throws:
-
NullPointerException
- if rhs is null
-
Since:
-
1.2
intersect
public 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)
################ ################ ################
############## ############## ############
############ ############ ########
########## ########## ####
######## ########
###### ######
#### ####
## ##
-
-
-
Parameters:
-
rhs - the Area to be intersected with this Area
-
Throws:
-
NullPointerException
- if rhs is null
-
Since:
-
1.2
exclusiveOr
public 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)
################ ################
############## ############## ## ##
############ ############ #### ####
########## ########## ###### ######
######## ######## ################
###### ###### ###### ######
#### #### #### ####
## ## ## ##
-
-
-
Parameters:
-
rhs - the Area to be exclusive ORed with this Area.
-
Throws:
-
NullPointerException
- if rhs is null
-
Since:
-
1.2
reset
public void reset()
-
Removes all of the geometry from this Area and restores it to an empty area.
-
-
-
Since:
-
1.2
isEmpty
public boolean isEmpty()
-
Tests whether this Area object encloses any area.
-
-
-
Returns:
-
true if this Area object represents an empty area; false otherwise.
-
Since:
-
1.2
isPolygonal
public boolean isPolygonal()
-
Tests whether this Area consists entirely of straight edged polygonal geometry.
-
-
-
Returns:
-
true if the geometry of this Area consists entirely of line segments; false otherwise.
-
Since:
-
1.2
isRectangular
public boolean isRectangular()
-
Tests whether this Area is rectangular in shape.
-
-
-
Returns:
-
true if the geometry of this Area is rectangular in shape; false otherwise.
-
Since:
-
1.2
isSingular
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.
-
-
-
Returns:
-
true if the Area is comprised of a single basic geometry; false otherwise.
-
Since:
-
1.2
getBounds2D
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.
-
-
Specified by:
-
getBounds2D
in interface
Shape
-
-
Returns:
-
the bounding Rectangle2D for the Area.
-
Since:
-
1.2
-
See Also:
-
Shape.getBounds()
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.
-
-
Specified by:
-
getBounds
in interface
Shape
-
-
Returns:
-
the bounding Rectangle for the Area.
-
Since:
-
1.2
-
See Also:
-
Shape.getBounds2D()
clone
public Object clone()
-
Returns an exact copy of this Area object.
-
-
Overrides:
-
clone
in class
Object
-
-
Returns:
-
Created clone object
-
Since:
-
1.2
-
See Also:
-
Cloneable
equals
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.
-
-
-
Parameters:
-
other - the Area to be compared to this Area
-
Returns:
-
true if the two geometries are equal; false otherwise.
-
Since:
-
1.2
transform
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.
-
-
-
Parameters:
-
t - the transformation used to transform the area
-
Throws:
-
NullPointerException
- if t is null
-
Since:
-
1.2
createTransformedArea
public 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.
-
-
-
Parameters:
-
t - the specified AffineTransform used to transform the new Area
-
Returns:
-
a new Area object representing the transformed geometry.
-
Throws:
-
NullPointerException
- if t is null
-
Since:
-
1.2
contains
public boolean contains(double x,
double y)
-
Tests if the specified coordinates are inside the boundary of the Shape.
Tests if a specifed point lies inside the boundary of this Area object.
-
-
Specified by:
-
contains
in interface
Shape
-
-
Parameters:
-
x - the specified X coordinate to be tested
-
y - the specified Y coordinate to be tested
x, y - the specified point
-
Returns:
-
true if the specified coordinates are inside the Shape boundary; false otherwise.
-
Since:
-
1.2
true if the point lies completely within the interior of the Area; false otherwise.
contains
public boolean contains(Point2D p)
-
Tests if a specified
Point2D
is
lies
inside the boundary of the
Shape.
this Area object.
-
-
Specified by:
-
contains
in interface
Shape
-
-
Parameters:
-
p - the
specified
Point2D to
be tested
test
-
Returns:
-
true if the specified Point2D
is inside
lies completely within
the
boundary
interior
of the
Shape;
Area;
false otherwise. -
Since:
Throws:
-
1.2
NullPointerException
- if p is null
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 rectanglar area to be considered contained within the Shape.
Tests whether or not the interior of this Area object completely contains the specified rectangular area.
The Shape.contains() method allows a Shape implementation to conservatively return false when:
-
the intersect method returns true and
-
the calculations to determine whether or not the Shape entirely contains the rectangular area are prohibitively expensive.
This means that for some 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 interface
Shape
-
-
Parameters:
-
x
x, y
- the
X coordinate
coordinates
of the
upper-left
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 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.
true if the specified rectangular area lies completely within the interior of the Area; false otherwise.
-
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 returns true and
-
the calculations to determine whether or not the Shape entirely contains the Rectangle2D are prohibitively expensive.
This means that for some 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.
Tests whether or not the interior of this Area object completely contains the specified Rectangle2D.
-
-
Specified by:
-
contains
in interface
Shape
-
-
Parameters:
-
r -
The specified
the
Rectangle2D
to test
-
Returns:
-
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.
true if the Rectangle2D lies completely within the interior of the Area; false otherwise.
-
Since:
Throws:
-
1.2
NullPointerException
- if r is null
-
See Also:
-
Shape.contains(double, double, double, double)
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.
Tests whether the interior of this Area object intersects the interior of 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.
This means that for some 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 interface
Shape
-
-
Parameters:
-
x
x, y
- the
X coordinate
coordinates
of the
upper-left
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
teh
specified rectangular area -
Returns:
-
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.
true if the interior intersects the specified rectangular area; 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 the Shape intersect, but
-
the calculations to accurately determine this intersection are prohibitively expensive.
This means that for some 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.
Tests whether the interior of this Area object intersects the interior of the specified Rectangle2D.
-
-
Specified by:
-
intersects
in interface
Shape
-
-
Parameters:
-
r - the
specified
Rectangle2D
to test for intersection
-
Returns:
-
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.
true if the interior intersects the specified Rectangle2D; false otherwise.
-
Since:
Throws:
-
1.2
NullPointerException
- if r is null
-
See Also:
-
Shape.intersects(double, double, double, double)
getPathIterator
public PathIterator getPathIterator(AffineTransform at)
-
Creates a
PathIterator
for the outline of this Area object. This Area object is unchanged.
-
-
Specified by:
-
getPathIterator
in interface
Shape
-
-
Parameters:
-
at - an optional AffineTransform to be applied to the coordinates as they are returned in the iteration, or null if untransformed coordinates are desired
-
Returns:
-
the PathIterator object that returns the geometry of the outline of this Area, one segment at a time.
-
Since:
-
1.2
getPathIterator
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.
-
-
Specified by:
-
getPathIterator
in interface
Shape
-
-
Parameters:
-
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
end points
endpoints
-
Returns:
-
the PathIterator object that returns the geometry of the outline of this Area, one segment at a time.
-
Since:
-
1.2