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Eclipse Platform
Release 3.0

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org.eclipse.swt.graphics
Class Region

java.lang.Object
  org.eclipse.swt.graphics.Region

public final class Region

extends Object

Instances of this class represent areas of an x-y coordinate system that are aggregates of the areas covered by a number of rectangles.

Application code must explicitly invoke the Region.dispose() method to release the operating system resources managed by each instance when those instances are no longer required.

Field Summary

int	handle the OS resource for the region (Warning: This field is platform dependent)

Constructor Summary

Region()
Constructs a new empty region.

Region(Device device)
Constructs a new empty region.

Method Summary

void	add(int[] pointArray) Adds the given polygon to the collection of rectangles the receiver maintains to describe its area.
void	add(Rectangle rect) Adds the given rectangle to the collection of rectangles the receiver maintains to describe its area.
void	add(Region region) Adds all of the rectangles which make up the area covered by the argument to the collection of rectangles the receiver maintains to describe its area.
boolean	contains(int x, int y) Returns true if the point specified by the arguments is inside the area specified by the receiver, and false otherwise.
boolean	contains(Point pt) Returns true if the given point is inside the area specified by the receiver, and false otherwise.
void	dispose() Disposes of the operating system resources associated with the region.
boolean	equals(Object object) Compares the argument to the receiver, and returns true if they represent the same object using a class specific comparison.
Rectangle	getBounds() Returns a rectangle which represents the rectangular union of the collection of rectangles the receiver maintains to describe its area.
int	hashCode() Returns an integer hash code for the receiver.
void	intersect(Rectangle rect) Intersects the given rectangle to the collection of rectangles the receiver maintains to describe its area.
void	intersect(Region region) Intersects all of the rectangles which make up the area covered by the argument to the collection of rectangles the receiver maintains to describe its area.
boolean	intersects(int x, int y, int width, int height) Returns true if the rectangle described by the arguments intersects with any of the rectangles the receiver mainains to describe its area, and false otherwise.
boolean	intersects(Rectangle rect) Returns true if the given rectangle intersects with any of the rectangles the receiver mainains to describe its area and false otherwise.
boolean	isDisposed() Returns true if the region has been disposed, and false otherwise.
boolean	isEmpty() Returns true if the receiver does not cover any area in the (x, y) coordinate plane, and false if the receiver does cover some area in the plane.
void	subtract(int[] pointArray) Subtracts the given polygon from the collection of rectangles the receiver maintains to describe its area.
void	subtract(Rectangle rect) Subtracts the given rectangle from the collection of rectangles the receiver maintains to describe its area.
void	subtract(Region region) Subtracts all of the rectangles which make up the area covered by the argument from the collection of rectangles the receiver maintains to describe its area.
String	toString() Returns a string containing a concise, human-readable description of the receiver.
static Region	win32_new(Device device, int handle) Invokes platform specific functionality to allocate a new region.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

handle

public int handle

the OS resource for the region (Warning: This field is platform dependent)

Constructor Detail

Region

public Region()

Constructs a new empty region.

Throws:

SWTError -

• ERROR_NO_HANDLES if a handle could not be obtained for region creation

Region

public Region(Device device)

Constructs a new empty region.

You must dispose the region when it is no longer required.

Parameters:

device - the device on which to allocate the region

Throws:

SWTError -

• ERROR_NO_HANDLES if a handle could not be obtained for region creation

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if device is null and there is no current device

Since:

3.0

See Also:

dispose()

Method Detail

add

public void add(int[] pointArray)

Adds the given polygon to the collection of rectangles the receiver maintains to describe its area.

Parameters:

pointArray - points that describe the polygon to merge with the receiver

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the argument is null

SWTException -

• ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

Since:

3.0

add

public void add(Rectangle rect)

Adds the given rectangle to the collection of rectangles the receiver maintains to describe its area.

Parameters:

rect - the rectangle to merge with the receiver

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the argument is null
• ERROR_INVALID_ARGUMENT - if the rectangle's width or height is negative

SWTException -

• ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

add

public void add(Region region)

Adds all of the rectangles which make up the area covered by the argument to the collection of rectangles the receiver maintains to describe its area.

Parameters:

region - the region to merge

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the argument is null
• ERROR_INVALID_ARGUMENT - if the argument has been disposed

SWTException -

• ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

contains

public boolean contains(int x,
                        int y)

Returns true if the point specified by the arguments is inside the area specified by the receiver, and false otherwise.

Parameters:

x - the x coordinate of the point to test for containment

y - the y coordinate of the point to test for containment

Returns:

true if the region contains the point and false otherwise

Throws:

SWTException -

• ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

contains

public boolean contains(Point pt)

Returns true if the given point is inside the area specified by the receiver, and false otherwise.

Parameters:

pt - the point to test for containment

Returns:

true if the region contains the point and false otherwise

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the argument is null

SWTException -

• ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

dispose

public void dispose()

Disposes of the operating system resources associated with the region. Applications must dispose of all regions which they allocate.

equals

public boolean equals(Object object)

Compares the argument to the receiver, and returns true if they represent the same object using a class specific comparison.

Parameters:

object - the object to compare with this object

Returns:

true if the object is the same as this object and false otherwise

See Also:

hashCode()

getBounds

public Rectangle getBounds()

Returns a rectangle which represents the rectangular union of the collection of rectangles the receiver maintains to describe its area.

Returns:

a bounding rectangle for the region

Throws:

SWTException -

• ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

See Also:

Rectangle.union(org.eclipse.swt.graphics.Rectangle)

hashCode

public int hashCode()

Returns an integer hash code for the receiver. Any two objects which return true when passed to equals must return the same value for this method.

Returns:

the receiver's hash

See Also:

equals(java.lang.Object)

intersect

public void intersect(Rectangle rect)

Intersects the given rectangle to the collection of rectangles the receiver maintains to describe its area.

Parameters:

rect - the rectangle to intersect with the receiver

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the argument is null
• ERROR_INVALID_ARGUMENT - if the rectangle's width or height is negative

SWTException -

• ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

Since:

3.0

intersect

public void intersect(Region region)

Intersects all of the rectangles which make up the area covered by the argument to the collection of rectangles the receiver maintains to describe its area.

Parameters:

region - the region to intersect

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the argument is null
• ERROR_INVALID_ARGUMENT - if the argument has been disposed

SWTException -

• ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

Since:

3.0

intersects

public boolean intersects(int x,
                          int y,
                          int width,
                          int height)

Returns true if the rectangle described by the arguments intersects with any of the rectangles the receiver mainains to describe its area, and false otherwise.

Parameters:

x - the x coordinate of the origin of the rectangle

y - the y coordinate of the origin of the rectangle

width - the width of the rectangle

height - the height of the rectangle

Returns:

true if the rectangle intersects with the receiver, and false otherwise

Throws:

SWTException -

• ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

See Also:

Rectangle.intersects(int, int, int, int)

intersects

public boolean intersects(Rectangle rect)

Returns true if the given rectangle intersects with any of the rectangles the receiver mainains to describe its area and false otherwise.

Parameters:

rect - the rectangle to test for intersection

Returns:

true if the rectangle intersects with the receiver, and false otherwise

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the argument is null

SWTException -

• ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

See Also:

Rectangle.intersects(int, int, int, int)

isDisposed

public boolean isDisposed()

Returns true if the region has been disposed, and false otherwise.

This method gets the dispose state for the region. When a region has been disposed, it is an error to invoke any other method using the region.

Returns:

true when the region is disposed, and false otherwise

isEmpty

public boolean isEmpty()

Returns true if the receiver does not cover any area in the (x, y) coordinate plane, and false if the receiver does cover some area in the plane.

Returns:

true if the receiver is empty, and false otherwise

Throws:

SWTException -

• ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

subtract

public void subtract(int[] pointArray)

Subtracts the given polygon from the collection of rectangles the receiver maintains to describe its area.

Parameters:

pointArray - points that describe the polygon to merge with the receiver

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the argument is null

SWTException -

• ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

Since:

3.0

subtract

public void subtract(Rectangle rect)

Subtracts the given rectangle from the collection of rectangles the receiver maintains to describe its area.

Parameters:

rect - the rectangle to subtract from the receiver

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the argument is null
• ERROR_INVALID_ARGUMENT - if the rectangle's width or height is negative

SWTException -

• ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

Since:

3.0

subtract

public void subtract(Region region)

Subtracts all of the rectangles which make up the area covered by the argument from the collection of rectangles the receiver maintains to describe its area.

Parameters:

region - the region to subtract

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the argument is null
• ERROR_INVALID_ARGUMENT - if the argument has been disposed

SWTException -

• ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

Since:

3.0

win32_new

public static Region win32_new(Device device,
                               int handle)

Invokes platform specific functionality to allocate a new region.

IMPORTANT: This method is not part of the public API for Region. It is marked public only so that it can be shared within the packages provided by SWT. It is not available on all platforms, and should never be called from application code.

Parameters:

device - the device on which to allocate the region

handle - the handle for the region

Returns:

a new region object containing the specified device and handle

toString

public String toString()

Returns a string containing a concise, human-readable description of the receiver.

Returns:

a string representation of the receiver