acm.graphics

Class GCompound

java.lang.Object

acm.graphics.GObject

acm.graphics.GCompound

All Implemented Interfaces:

GContainer, GScalable, java.lang.Cloneable

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.

Field Summary

Fields inherited from interface acm.graphics.GContainer

BACK_TO_FRONT, FRONT_TO_BACK

Constructor Summary

Constructors

Constructor and Description
GCompound() Creates a new GCompound object with no internal components.

Method Summary

Methods

Modifier and Type	Method and Description
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.
java.util.Iterator	iterator() Returns an Iterator that cycles through the elements within this container in the default direction, which is from back to front.
java.util.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	paint(java.awt.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 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.

Methods inherited from class acm.graphics.GObject

addActionListener, addMouseListener, addMouseMotionListener, contains, fireActionEvent, fireActionEvent, getColor, getHeight, getLocation, getParent, getSize, getWidth, getX, getY, isVisible, move, movePolar, pause, removeActionListener, removeMouseListener, removeMouseMotionListener, sendBackward, sendForward, sendToBack, sendToFront, setColor, setLocation, setLocation, setParent, setVisible, toString

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

GCompound

public GCompound()

Creates a new GCompound object with no internal components.

Method Detail

add

public void add(GObject gobj)

Adds a new graphical object to this GCompound.

Specified by:

add in interface GContainer

Parameters:

gobj - The graphical object to add

add

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).

Specified by:

add in interface GContainer

Parameters:

gobj - The graphical object to add

x - The new x-coordinate for the object

y - The new y-coordinate for the object

add

public final void add(GObject gobj,
       GPoint pt)

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

Specified by:

add in interface GContainer

Parameters:

gobj - The graphical object to add

pt - A GPoint object giving the coordinates of the point

remove

public void remove(GObject gobj)

Removes a graphical object from this GCompound.

Specified by:

remove in interface GContainer

Parameters:

gobj - The graphical object to remove

removeAll

public void removeAll()

Removes all graphical objects from this GCompound.

Specified by:

removeAll in interface GContainer

getElementCount

public int getElementCount()

Returns the number of graphical objects stored in this container.

Specified by:

getElementCount in interface GContainer

Returns:

The number of graphical objects in this container

getElement

public GObject getElement(int index)

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

Specified by:

getElement in interface GContainer

Parameters:

index - The index of the component to return

Returns:

The graphical object at the specified index

getElementAt

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.

Specified by:

getElementAt in interface GContainer

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

getElementAt

public final GObject getElementAt(GPoint pt)

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

Specified by:

getElementAt in interface GContainer

Parameters:

pt - The coordinates being tested

Returns:

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

iterator

public java.util.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.

Returns:

An Iterator ranging over the elements of the container from back to front

iterator

public java.util.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.

Returns:

An Iterator ranging over the elements of the container in the specified direction

paint

public void paint(java.awt.Graphics g)

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

Specified by:

paint in class GObject

Parameters:

g - The graphics context into which the painting is done

scale

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.

Specified by:

scale in interface GScalable

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

scale

public final void scale(double sf)

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

Specified by:

scale in interface GScalable

Parameters:

sf - The factor used to scale all coordinates in both dimensions

getBounds

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.

Specified by:

getBounds in class GObject

Returns:

A GRectangle that bounds the components of this object

contains

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.

Overrides:

contains in class GObject

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

getCanvasPoint

public final GPoint getCanvasPoint(GPoint localPoint)

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

Parameters:

localPoint - The coordinates in the space of the compound

Returns:

The coordinates in the space of the enclosing GCanvas

getCanvasPoint

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.

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

getLocalPoint

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.

Parameters:

canvasPoint - The coordinates in the space of the enclosing GCanvas

Returns:

The coordinates in the space of the compound

getLocalPoint

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.

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

markAsComplete

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.