acm.graphics
Class GCompound

java.lang.Object
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  +--acm.graphics.GObject
        |
        +--acm.graphics.GCompound

public class GCompound extends GObject implements GContainer

This class defines a graphical object that consists of a collection of other graphical objects. Once assembled, the internal objects can be manipulated as a unit.

Field Summary

static int	BACK_TO_FRONT Specifies that iterators should run from back to front
static int	FRONT_TO_BACK Specifies that iterators should run from front to back

Constructor Summary

GCompound()

Method Summary

void	add(GObject gobj) Adds a new graphical object to this GCompound.
void	add(GObject gobj, double x, double y) Adds a new graphical object to this GCompound and sets its location to the point (x, y).
void	add(GObject gobj, java.awt.Point pt) Adds the graphical object to this and sets its location to the specified point.
Rectangle	getBounds() Returns the bounding rectangle for this compound object, which consists of the union of the bounding rectangles for each of the components.
GObject	getElement(int index) Returns the graphical object at the specified index, numbering from back to front in the stacking order.
GObject	getElementAt(double x, double y) Returns the topmost graphical object that contains the point (x, y), or null if no such object exists.
GObject	getElementAt(Point pt) Returns the topmost graphical object that contains the specified point, or null if no such object exists.
int	getElementCount() Returns the number of graphical objects stored in this container.
double	getHeight() Returns the height of this compound object, which is the vertical extent of its components.
Dimension	getSize() Returns the size of this compound object, which is defined to be the size of the bounding box containing all of its components.
double	getWidth() Returns the width of this compound object, which is the horizontal extent of its components.
Iterator	iterator() Returns an Iterator that cycles through the elements within this container in the default direction, which is from back to front.
Iterator	iterator(int direction) Returns an Iterator that cycles through the elements within this container in the specified direction, which must be one of the constants FRONT_TO_BACK or BACK_TO_FRONT.
void	paint(Graphics g) Implements the paint operation for this graphical object.
void	remove(GObject gobj) Removes a graphical object from this GCompound.
void	removeAll() Removes all graphical objects from this GCompound.
void	scale(double sx, double sy) Scales every object contained in this compound by the scale factors sx and sy.

Inherited Method Summary

void	addMouseListener(MouseListener listener) Adds a mouse listener to this graphical object. [Inherited from GObject]
void	addMouseMotionListener(MouseMotionListener listener) Adds a mouse motion listener to this graphical object. [Inherited from GObject]
boolean	contains(double x, double y) Checks to see whether a point is inside the object. [Inherited from GObject]
Point	getLocation() Returns the nearest Point corresponding to the location of this object. [Inherited from GObject]
double	getX() Returns the x-coordinate of the object. [Inherited from GObject]
double	getY() Returns the y-coordinate of the object. [Inherited from GObject]
boolean	isVisible() Checks to see whether this object is visible. [Inherited from GObject]
void	moveToBack() Moves this object to the back of the display in stacking order. [Inherited from GObject]
void	moveToFront() Moves this object to the front of the display in stacking order. [Inherited from GObject]
void	removeMouseListener(MouseListener listener) Removes a mouse listener from this graphical object. [Inherited from GObject]
void	removeMouseMotionListener(MouseMotionListener listener) Removes a mouse motion listener from this graphical object. [Inherited from GObject]
void	scale(double sf) Scales the object on the screen by the scale factor sf, which applies in both dimensions. [Inherited from GObject]
void	setLocation(double x, double y) Sets the location of this object to the point (x, y). [Inherited from GObject]
void	setVisible(boolean visible) Sets whether this object is visible. [Inherited from GObject]
void	translate(double dx, double dy) Moves the object on the screen using the displacements dx and dy. [Inherited from GObject]

Field Detail

public static final int BACK_TO_FRONT

Specifies that iterators should run from back to front

public static final int FRONT_TO_BACK

Specifies that iterators should run from front to back

Constructor Detail

public GCompound()

Creates a new GCompound object with no internal components.

Usage:

GCompound gcomp = new GCompound();

Method Detail

public void add(GObject gobj)

Adds a new graphical object to this GCompound.

Usage:

gcomp.add(gobj);

Parameter:

gobj	The graphical object to add

Specified by:

add in interface GContainer

public void add(GObject gobj, double x, double y)

Adds a new graphical object to this GCompound and sets its location to the point (x, y).

Usage:

gcomp.add(gobj);

Parameters:

gobj	The graphical object to add
x	The new x-coordinate for the object
y	The new y-coordinate for the object

Specified by:

add in interface GContainer

public final void add(GObject gobj, Point pt)

Adds the graphical object to this and sets its location to the specified point.

Usage:

gcomp.add(gobj, pt);

Parameters:

gobj	The graphical object to add
pt	A Point object giving the coordinates of the point

Specified by:

add in interface GContainer

public Rectangle getBounds()

Returns the bounding rectangle for this compound object, which consists of the union of the bounding rectangles for each of the components.

Usage:	Rectangle bounds = gcomp.getBounds();
Returns:	A Rectangle that bounds the components of this object

public GObject getElement(int index)

Returns the graphical object at the specified index, numbering from back to front in the stacking order.

Usage:

GObject gobj = gcomp.getElement(index);

Parameter:

index

The index of the component to return

Returns:

The graphical object at the specified index

Specified by:

getElement in interface GContainer

public GObject getElementAt(double x, double y)

Returns the topmost graphical object that contains the point (x, y), or null if no such object exists. Note that these coordinates are relative to the location of the compound object and not to the canvas in which it is displayed.

Usage:

GObject gobj = gcomp.getElementAt(x, y);

Parameters:

x	The x-coordinate of the point being tested
y	The y-coordinate of the point being tested

Returns:

The graphical object at the specified location, or null if no such object exists

Specified by:

getElementAt in interface GContainer

public final GObject getElementAt(Point pt)

Returns the topmost graphical object that contains the specified point, or null if no such object exists.

Usage:

GObject gobj = gc.getElementAt(pt);

Parameter:

pt	The coordinates being tested

Returns:

The graphical object at the specified location, or null if no such object exists

Specified by:

getElementAt in interface GContainer

public int getElementCount()

Returns the number of graphical objects stored in this container.

Usage:	int n = gcomp.getElementCount();
Returns:	The number of graphical objects in this container
Specified by:	getElementCount in interface GContainer

public double getHeight()

Returns the height of this compound object, which is the vertical extent of its components.

Usage:	double height = gcomp.getHeight();
Returns:	The height of this object on the screen

public Dimension getSize()

Returns the size of this compound object, which is defined to be the size of the bounding box containing all of its components.

Usage:	Dimension size = gcomp.getSize();
Returns:	The size of this object

public double getWidth()

Returns the width of this compound object, which is the horizontal extent of its components.

Usage:	double width = gcomp.getWidth();
Returns:	The width of this object

public Iterator iterator()

Returns an Iterator that cycles through the elements within this container in the default direction, which is from back to front. You can also run the iterator in the opposite direction by using the iterator(direction) form of this method.

Applets that want to run in browsers, however, should avoid using this method, because Iterator is not supported on 1.1 browsers. For maximum portability, you should rely instead on the getElementCount and getElement methods, which provide the same functionality in a browser-compatible way.

Usage:	Iterator i = gc.iterator();
Returns:	An Iterator ranging over the elements of the container from back to front

public Iterator iterator(int direction)

Returns an Iterator that cycles through the elements within this container in the specified direction, which must be one of the constants FRONT_TO_BACK or BACK_TO_FRONT.

for (Iterator i = gc.iterator(direction); i.hasNext(); )

Applets that want to run in browsers, however, should avoid using this method, because Iterator is not supported on 1.1 browsers. For maximum portability, you should rely instead on the getElementCount and getElement methods, which provide the same functionality in a browser-compatible way.

Usage:	Iterator i = gc.iterator(direction);
Returns:	An Iterator ranging over the elements of the container in the specified direction

public void paint(Graphics g)

Implements the paint operation for this graphical object. This method is not called directly by clients.

public void remove(GObject gobj)

Removes a graphical object from this GCompound.

Usage:

gcomp.remove(gobj);

Parameter:

gobj	The graphical object to remove

Specified by:

remove in interface GContainer

public void removeAll()

Removes all graphical objects from this GCompound.

Usage:	gcomp.removeAll();
Specified by:	removeAll in interface GContainer

public void scale(double sx, double sy)

Scales every object contained in this compound by the scale factors sx and sy. Automatic repaint is turned off during the scaling operation so that at most one repaint is performed.

Usage:

gcomp.scale(sx, sy);

Parameters:

sx	The factor used to scale all coordinates in the x direction
sy	The factor used to scale all coordinates in the y direction