acm.graphics
Class GCompound

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

public class GCompound extends GObject implements GContainer, GScalable

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.

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 the graphical object to this canvas and sets its location to the point (x, y).
void	add(GObject gobj, GPoint pt) Adds the graphical object to this canvas and sets its location to the specified point.
boolean	contains(double x, double y) Checks to see whether a point is "inside" the compound, which means that it is inside one of the components.
GRectangle	getBounds() Returns the bounding rectangle for this compound object, which consists of the union of the bounding rectangles for each of the components.
GPoint	getCanvasPoint(double x, double y) Converts the location of the specified point in this compound to the corresponding point in the enclosing canvas.
GPoint	getCanvasPoint(GPoint localPoint) Converts the location of the specified point in this compound to the corresponding point in the enclosing canvas.
GObject	getElement(int index) Returns the graphical object at the specified index, numbering from back to front in the the z dimension.
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(GPoint 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.
GPoint	getLocalPoint(double x, double y) Converts the specified point on the enclosing canvas to the corresponding point in the space of this compound.
GPoint	getLocalPoint(GPoint canvasPoint) Converts the location of the specified point on the enclosing canvas to the corresponding point in the space of this compound.
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 GContainer.FRONT_TO_BACK or GContainer.BACK_TO_FRONT.
void	markAsComplete() Calling this method makes it illegal to add or remove elements from the compound object.
void	remove(GObject gobj) Removes a graphical object from this GCompound.
void	removeAll() Removes all graphical objects from this GCompound.
void	scale(double sf) Scales the object on the screen by the scale factor sf, which applies in both dimensions.
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.
void	addMouseMotionListener(MouseMotionListener listener) Adds a mouse motion listener to this graphical object.
boolean	contains(GPoint pt) Checks to see whether a point is inside the object.
double	getHeight() Returns the height of this object, which is defined to be the height of the bounding box.
GPoint	getLocation() Returns the location of this object as a GPoint.
GDimension	getSize() Returns the size of the bounding box for this object.
double	getWidth() Returns the width of this object, which is defined to be the width of the bounding box.
double	getX() Returns the x-coordinate of the object.
double	getY() Returns the y-coordinate of the object.
boolean	isVisible() Checks to see whether the object is visible.
void	move(double dx, double dy) Moves the object on the screen using the displacements dx and dy.
void	movePolar(double r, double theta) Moves the object using displacements given in polar coordinates.
void	removeMouseListener(MouseListener listener) Removes a mouse listener from this graphical object.
void	removeMouseMotionListener(MouseMotionListener listener) Removes a mouse motion listener from this graphical object.
void	sendBackward() Moves this object one step toward the back in the z dimension.
void	sendForward() Moves this object one step toward the front in the z dimension.
void	sendToBack() Moves this object to the back of the display in the z dimension.
void	sendToFront() Moves this object to the front of the display in the z dimension.
void	setLocation(GPoint pt) Sets the location of this object to the specified point.
void	setLocation(double x, double y) Sets the location of the GCompound to the point (x, y).
void	setVisible(boolean visible) Sets the visibility status of the GCompound.

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

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

Usage:

gc.add(gobj, x, y);

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, GPoint pt)

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

Usage:

gc.add(gobj, pt);

Parameters:

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

Specified by:

add in interface GContainer

public boolean contains(double x, double y)

Checks to see whether a point is "inside" the compound, which means that it is inside one of the components.

Usage:

if (gcomp.contains(x, y)) . . .

Parameters:

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

Returns:

true if the point (x, y) is inside the compound, and false otherwise

public GRectangle getBounds()

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

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

public GPoint getCanvasPoint(double x, double y)

Converts the location of the specified point in this compound to the corresponding point in the enclosing canvas.

Usage:

canvasPoint = gcomp.getCanvasPoint(x, y);

Parameters:

x	The x coordinate in the space of the compound
y	The y coordinate in the space of the compound

Returns:

The coordinates in the space of the enclosing GCanvas

public final GPoint getCanvasPoint(GPoint localPoint)

Converts the location of the specified point in this compound to the corresponding point in the enclosing canvas.

Usage:

canvasPoint = gcomp.getCanvasPoint(localPoint);

Parameter:

localPoint

The coordinates in the space of the compound

Returns:

The coordinates in the space of the enclosing GCanvas

public GObject getElement(int index)

Returns the graphical object at the specified index, numbering from back to front in the the z dimension.

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 nullif no such object exists

Specified by:

getElementAt in interface GContainer

public final GObject getElementAt(GPoint 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 nullif 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 GPoint getLocalPoint(double x, double y)

Converts the specified point on the enclosing canvas to the corresponding point in the space of this compound.

Usage:

localPoint = gcomp.getCanvasPoint(x, y);

Parameters:

x	The x coordinate in the space of the space of the enclosing GCanvas
y	The y coordinate in the space of the space of the enclosing GCanvas

Returns:

The coordinates in the space of the compound

public final GPoint getLocalPoint(GPoint canvasPoint)

Converts the location of the specified point on the enclosing canvas to the corresponding point in the space of this compound.

Usage:

localPoint = gcomp.getLocalPoint(canvasPoint);

Parameter:

canvasPoint

The coordinates in the space of the enclosing GCanvas

Returns:

The coordinates in the space of the compound

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 GContainer.FRONT_TO_BACK or GContainer.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 markAsComplete()

Calling this method makes it illegal to add or remove elements from the compound object. Subclasses can invoke this method to protect the integrity of the structure from changes by the client.

Usage:

gcomp.markAsComplete();

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 final void scale(double sf)

Scales the object on the screen by the scale factor sf, which applies in both dimensions.

Usage:

gcomp.scale(sf);

Parameter:

sf	The factor used to scale all coordinates in both dimensions

Specified by:

scale in interface GScalable

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

Specified by:

scale in interface GScalable