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Java(TM) 2 Platform, Standard Edition, v1.2.2 API Specification: Interface Shape - JDK 5 Documentation v1.2.2, Java 2 SDK 英文文档

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java.awt
Interface Shape

All Known Implementing Classes:
Polygon, RectangularShape, Rectangle, Line2D, CubicCurve2D, Area, GeneralPath, QuadCurve2D
public interface Shape

The Shape interface provides definitions for objects that represent some form of geometric shape. The Shape is described by a PathIterator object, which can express the outline of the Shape as well as a rule for determining how the outline divides the 2D plane into interior and exterior points. Each Shape object provides callbacks to get the bounding box of the geometry, determine whether points or rectangles lie partly or entirely within the interior of the Shape, and retrieve a PathIterator object that describes the trajectory path of the Shape outline.

Definition of insideness: A point is considered to lie inside a Shape if and only if:

See Also:
PathIterator, AffineTransform, FlatteningPathIterator, GeneralPath

Method Summary
 boolean contains(double x, double y)
          Tests if the specified coordinates are inside the boundary of the Shape.
 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.
 boolean contains(Rectangle2D r)
          Tests if the interior of the Shape entirely contains the specified Rectangle2D.
 Rectangle getBounds()
          Returns an integer Rectangle that completely encloses the Shape.
 Rectangle2D getBounds2D()
          Returns a high precision and more accurate bounding box of the Shape than the getBounds method.
 PathIterator getPathIterator(AffineTransform at)
          Returns an iterator object that iterates along the Shape boundary and provides access to the geometry of the Shape outline.
 PathIterator getPathIterator(AffineTransform at, double flatness)
          Returns an iterator object that iterates along the Shape boundary and provides access to a flattened view of the Shape outline geometry.
 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.
 

Method Detail

getBounds

public Rectangle getBounds()
Returns an integer Rectangle that completely encloses the Shape. Note that there is no guarantee that the returned Rectangle is the smallest bounding box that encloses the Shape, only that the Shape lies entirely within the indicated Rectangle. The returned Rectangle might also fail to completely enclose the Shape if the Shape overflows the limited range of the integer data type. The getBounds2D method generally returns a tighter bounding box due to its greater flexibility in representation.
Returns:
an integer Rectangle that completely encloses the Shape.
See Also:
getBounds2D()

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.
Returns:
an instance of Rectangle2D that is a high-precision bounding box of the Shape.
See Also:
getBounds()

contains

public boolean contains(double x,
                        double y)
Tests if the specified coordinates are inside the boundary of the Shape.
Parameters:
x, y - the specified coordinates
Returns:
true if the specified coordinates are inside the Shape boundary; false otherwise.

contains

public boolean contains(Point2D p)
Tests if a specified Point2D is inside the boundary of the Shape.
Parameters:
p - a specified Point2D
Returns:
true if the specified Point2D is inside the boundary of the Shape; false otherwise.

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.

This method might 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 this method might return true even though the rectangular area does not intersect the Shape. The Area class can be used to perform more accurate computations of geometric intersection for any Shape object if a more precise answer is required.
Parameters:
x, y - the coordinates 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 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.
See Also:
Area

intersects

public boolean intersects(Rectangle2D r)
Tests if the interior of the Shape intersects the interior of a specified Rectangle2D. This method might 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 this method might return true even though the Rectangle2D does not intersect the Shape.
Parameters:
r - the specified Rectangle2D
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.
See Also:
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 rectanglar area to be considered contained within the Shape.

This method might 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 this method might return false even though the Shape contains the rectangular area. The Area class can be used to perform more accurate computations of geometric intersection for any Shape object if a more precise answer is required.
Parameters:
x, y - the coordinates 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.
See Also:
Area, intersects(double, double, double, double)

contains

public boolean contains(Rectangle2D r)
Tests if the interior of the Shape entirely contains the specified Rectangle2D. This method might 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 this method might return false even though the Shape contains the Rectangle2D. The Area class can be used to perform more accurate computations of geometric intersection for any Shape object if a more precise answer is required.
Parameters:
r - The specified Rectangle2D
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.
See Also:
contains(double, double, double, double)

getPathIterator

public PathIterator getPathIterator(AffineTransform at)
Returns an iterator object that iterates along the Shape boundary and provides access to the geometry of the Shape outline. If an optional AffineTransform is specified, the coordinates returned in the iteration are transformed accordingly.

Each call to this method returns a fresh PathIterator object that traverses the geometry of the Shape object independently from any other PathIterator objects in use at the same time.

It is recommended, but not guaranteed, that objects implementing the Shape interface isolate iterations that are in process from any changes that might occur to the original object's geometry during such iterations.

Before using a particular implementation of the Shape interface in more than one thread simultaneously, refer to its documentation to verify that it guarantees that iterations are isolated from modifications.

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:
a new PathIterator object, which independently traverses the geometry of the Shape.

getPathIterator

public PathIterator getPathIterator(AffineTransform at,
                                    double flatness)
Returns an iterator object that iterates along the Shape boundary and provides access to a flattened view of the Shape outline geometry.

Only SEG_MOVETO, SEG_LINETO, and SEG_CLOSE point types are returned by the iterator.

If an optional AffineTransform is specified, the coordinates returned in the iteration are transformed accordingly.

The amount of subdivision of the curved segments is controlled by the flatness parameter, which specifies the maximum distance that any point on the unflattened transformed curve can deviate from the returned flattened path segments. Note that a limit on the accuracy of the flattened path might be silently imposed, causing very small flattening parameters to be treated as larger values. This limit, if there is one, is defined by the particular implementation that is used.

Each call to this method returns a fresh PathIterator object that traverses the Shape object geometry independently from any other PathIterator objects in use at the same time.

It is recommended, but not guaranteed, that objects implementing the Shape interface isolate iterations that are in process from any changes that might occur to the original object's geometry during such iterations.

Before using a particular implementation of this interface in more than one thread simultaneously, refer to its documentation to verify that it guarantees that iterations are isolated from modifications.

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 distance that the line segments used to approximate the curved segments are allowed to deviate from any point on the original curve
Returns:
a new PathIterator that independently traverses the Shape geometry.
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