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Area (Java 2 Platform SE v1.4.1) - JDK 5 Documentation v1.4.1, Java 2 SDK 英文文档

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java.awt.geom
Class Area

java.lang.Object
  |
  +--java.awt.geom.Area

All Implemented Interfaces:

Cloneable, Shape

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public class Area

extends Object

implements Shape, Cloneable

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.

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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 a specifed point lies inside the boundary of this Area object.
boolean	contains(double x, double y, double w, double h)           Tests whether or not the interior of this Area object completely contains the specified rectangular area.
boolean	contains(Point2D p)           Tests if a specified Point2D lies inside the boundary of the this Area object.
boolean	contains(Rectangle2D p)           Tests whether or not the interior of 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 whether the interior of this Area object intersects the interior of the specified rectangular area.
boolean	intersects(Rectangle2D p)           Tests whether the interior of this Area object intersects the interior of 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.

 

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

 

Constructor Detail

Area

public Area()

Default constructor which creates an empty area.

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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

Method Detail

add

public void add(Area rhs)

Adds the shape of the specified Area to the shape of this Area. Addition is achieved through union.

Parameters:

rhs - the Area to be added to the current shape

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subtract

public void subtract(Area rhs)

Subtracts the shape of the specified Area from the shape of this Area.

Parameters:

rhs - the Area to be subtracted from the current shape

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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.

Parameters:

rhs - the Area to be intersected with this Area

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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.

Parameters:

rhs - the Area to be exclusive ORed with this Area.

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reset

public void reset()

Removes all of the geometry from this Area and restores it to an empty area.

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isEmpty

public boolean isEmpty()

Tests whether this Area object encloses any area.

Returns:

true if this Area object represents an empty area; false otherwise.

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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.

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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.

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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.

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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.

See Also:

Shape.getBounds()

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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.

See Also:

Shape.getBounds2D()

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clone

public Object clone()

Returns an exact copy of this Area object.

Overrides:

clone in class Object

Returns:

Created clone object

See Also:

Cloneable

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equals

public boolean equals(Area other)

Tests whether the geometries of the two Area objects are equal.

Parameters:

other - the Area to be compared to this Area

Returns:

true if the two geometries are equal; false otherwise.

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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

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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.

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contains

public boolean contains(double x,
                        double y)

Tests if a specifed point lies inside the boundary of this Area object.

Specified by:

contains in interface Shape

Returns:

true if the point lies completely within the interior of the Area; false otherwise.

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contains

public boolean contains(Point2D p)

Tests if a specified Point2D lies inside the boundary of the this Area object.

Specified by:

contains in interface Shape

Parameters:

p - the Point2D to test

Returns:

true if the specified Point2D lies completely within the interior of the Area; false otherwise.

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contains

public boolean contains(double x,
                        double y,
                        double w,
                        double h)

Tests whether or not the interior of this Area object completely contains the specified rectangular area.

Specified by:

contains in interface Shape

Parameters:

w - the width of the specified rectangular area

h - the height of the specified rectangular area

Returns:

true if the specified rectangular area lies completely within the interior of the Area; false otherwise.

See Also:

Area, Shape.intersects(double, double, double, double)

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contains

public boolean contains(Rectangle2D p)

Tests whether or not the interior of this Area object completely contains the specified Rectangle2D.

Specified by:

contains in interface Shape

Parameters:

p - the Rectangle2D to test

Returns:

true if the Rectangle2D lies completely within the interior of the Area; false otherwise.

See Also:

Shape.contains(double, double, double, double)

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intersects

public boolean intersects(double x,
                          double y,
                          double w,
                          double h)

Tests whether the interior of this Area object intersects the interior of the specified rectangular area.

Specified by:

intersects in interface Shape

Parameters:

w - the width of the specified rectangular area

h - the height of teh specified rectangular area

Returns:

true if the interior intersects the specified rectangular area; false otherwise;

See Also:

Area

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intersects

public boolean intersects(Rectangle2D p)

Tests whether the interior of this Area object intersects the interior of the specified Rectangle2D.

Specified by:

intersects in interface Shape

Parameters:

p - the Rectangle2D to test for intersection

Returns:

true if the interior intersects the specified Rectangle2D; false otherwise.

See Also:

Shape.intersects(double, double, double, double)

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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.

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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 endpoints

Returns:

the PathIterator object that returns the geometry of the outline of this Area, one segment at a time.

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