acm.graphics
Class GObject

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

Direct Known Subclasses:

GArc, GCompound, GImage, GLine, GOval, GPen, GPolygon, GRect, GString

public abstract class GObject implements Cloneable

This class is the common superclass of all graphical objects that can be displayed on a GCanvas. Because it is an abstract class, you are not allowed to construct an object whose class is GObject directly. What you do instead is construct one of the concrete subclasses like GRect or GLine. The purpose of this class definition is to define methods that apply to all graphical objects regardless of their specific class.

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(double x, double y) Checks to see whether a point is inside the object.
boolean	contains(Point pt) Checks to see whether a point is inside the object, where the point is specified as a Point, as defined in java.awt.
Rectangle	getBounds() Returns the bounding box of this object, which is defined to be the smallest rectangle that covers everything drawn by the figure.
Color	getColor() Returns the color used to display this object.
Component	getComponent() Returns the component in which this object is installed, or null if none exists.
Color	getFillColor() Returns the color used to display the filled region of this object.
double	getHeight() Returns the height of this object.
Point	getLocation() Returns the nearest Point corresponding to the location of this object.
GContainer	getParent() Returns the parent of this object, which is the canvas or compound object in which it is enclosed.
Dimension	getSize() Returns the size of this object as a Dimension.
double	getWidth() Returns the width of this object.
double	getX() Returns the x-coordinate of the object.
double	getY() Returns the y-coordinate of the object.
boolean	isFilled() Returns whether this object is filled.
boolean	isVisible() Checks to see whether this object is visible.
void	moveToBack() Moves this object to the back of the display in stacking order.
void	moveToFront() Moves this object to the front of the display in stacking order.
abstract void	paint(Graphics g) All subclasses of GObject must define a paint method which allows the object to draw itself on the Graphics context passed in as the parameter g.
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	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 the object on the screen by the scale factors sx and sy.
void	setColor(Color c) Sets the color used to display this object.
void	setFillColor(Color c) Sets the color used to display the filled region of this object.
void	setFilled(boolean fill) Sets whether this object is filled.
void	setLocation(double x, double y) Sets the location of this object to the point (x, y).
void	setLocation(Point pt) Sets the location of this object to the specified point, specified using the standard Point class from java.awt.
void	setSize(Dimension size) Changes the size of this object to the specified Dimension object as defined in java.awt.
void	setSize(double width, double height) Changes the size of this object to the specified width and height.
void	setVisible(boolean visible) Sets whether this object is visible.
void	translate(double dx, double dy) Moves the object on the screen using the displacements dx and dy.

Method Detail

public void addMouseListener(MouseListener listener)

Adds a mouse listener to this graphical object.

Usage:

gobj.addMouseListener(listener);

Parameter:

listener

Any object that implements the MouseListener interface

public void addMouseMotionListener(MouseMotionListener listener)

Adds a mouse motion listener to this graphical object.

Usage:

gobj.addMouseMotionListener(listener);

Parameter:

listener

Any object that implements the MouseMotionListener interface

public boolean contains(double x, double y)

Checks to see whether a point is inside the object. By default, this method simply checks to see if the point is inside the bounding box. Most subclasses will need to override this to check whether the point is contained in the shape.

Usage:

if (gobj.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 object, and false otherwise

public final boolean contains(Point pt)

Checks to see whether a point is inside the object, where the point is specified as a Point, as defined in java.awt.

Usage:

if (gobj.contains(pt)) . . .

Parameter:

pt	The point being tested

Returns:

true if the point is inside the object, and false otherwise

public Rectangle getBounds()

Returns the bounding box of this object, which is defined to be the smallest rectangle that covers everything drawn by the figure. The coordinates of this rectangle do not necessarily match the location returned by getLocation. Given a GString object, for example, getLocation returns the coordinates of the point on the baseline at which the string begins; getBounds, by contrast, returns a rectangle that covers the entire window area occupied by the string.

Usage:	Rectangle bounds = gobj.getBounds();
Returns:	The bounding box for this object

public Color getColor()

Returns the color used to display this object.

Usage:	Color color = gobj.getColor();
Returns:	The color used to display this object

public Component getComponent()

Returns the component in which this object is installed, or null if none exists.

public Color getFillColor()

Returns the color used to display the filled region of this object. If none has been set, getFillColor returns the color of the object.

Usage:	Color color = gobj.getFillColor();
Returns:	The color used to display the filled region of this object

public double getHeight()

Returns the height of this object. Note that this is the height as established by the setSize method and may not correspond to the apparent height of the figure. To get the actual bounds of the figure, use getBounds.

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

public Point getLocation()

Returns the nearest Point corresponding to the location of this object.

Usage:	Point pt = gobj.getLocation();
Returns:	The nearest Point corresponding to the location of this object

public GContainer getParent()

Returns the parent of this object, which is the canvas or compound object in which it is enclosed.

Usage:	GContainer parent = gobj.getParent();
Returns:	The parent of this object

public Dimension getSize()

Returns the size of this object as a Dimension. Note that this is the size as established by the setSize method and may not correspond to the apparent size of the figure. To get the actual bounds of the figure, use getBounds.

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

public double getWidth()

Returns the width of this object. Note that this is the width as established by the setSize method and may not correspond to the apparent width of the figure. To get the actual bounds of the figure, use getBounds.

Usage:	double width = gobj.getWidth();
Returns:	The width of this object on the screen

public double getX()

Returns the x-coordinate of the object.

Usage:	double x = gobj.getX();
Returns:	The x-coordinate of the object

public double getY()

Returns the y-coordinate of the object.

Usage:	double y = gobj.getY();
Returns:	The y-coordinate of the object

public boolean isFilled()

Returns whether this object is filled.

Usage:	if (gobj.isFilled()) . . .
Returns:	The color used to display the object

public boolean isVisible()

Checks to see whether this object is visible.

Usage:	if (gobj.isVisible()) . . .
Returns:	true if the object is visible, otherwise false

public void moveToBack()

Moves this object to the back of the display in stacking order. By moving it to the back, this object will appear to be behind the other graphical objects on the display and may be obscured by other objects in front.

Usage:

gobj.moveToBack();

public void moveToFront()

Moves this object to the front of the display in stacking order. By moving it to the front, this object will appear to be on top of the other graphical objects on the display and may hide any objects that are further back.

Usage:

gobj.moveToFront();

public abstract void paint(Graphics g)

All subclasses of GObject must define a paint method which allows the object to draw itself on the Graphics context passed in as the parameter g.

Usage:

gobj.paint(g);

Parameter:

g	The graphics context into which the painting is done

public void removeMouseListener(MouseListener listener)

Removes a mouse listener from this graphical object.

Usage:

gobj.removeMouseListener(listener);

Parameter:

listener

The listener object to remove

public void removeMouseMotionListener(MouseMotionListener listener)

Removes a mouse motion listener from this graphical object.

Usage:

gobj.removeMouseMotionListener(listener);

Parameter:

listener

The listener object to remove

public final void scale(double sf)

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

Usage:

gobj.scale(sf);

Parameter:

sf	The factor used to scale all coordinates in both dimensions

public void scale(double sx, double sy)

Scales the object on the screen by the scale factors sx and sy.

Usage:

gobj.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

public void setColor(Color c)

Sets the color used to display this object.

Usage:

gobj.setColor(color);

Parameter:

color

The color used to display this object

public void setFillColor(Color c)

Sets the color used to display the filled region of this object.

Usage:

gobj.setFillColor(color);

Parameter:

color

The color used to display the filled region of this object

public void setFilled(boolean fill)

Sets whether this object is filled.

Usage:

gobj.setFilled(fill);

Parameter:

fill	true if the object should be filled, false for an outline

public void setLocation(double x, double y)

Sets the location of this object to the point (x, y).

Usage:

gobj.setLocation(x, y);

Parameters:

x	The new x-coordinate for the object
y	The new y-coordinate for the object

public final void setLocation(Point pt)

Sets the location of this object to the specified point, specified using the standard Point class from java.awt.

public final void setSize(Dimension size)

Changes the size of this object to the specified Dimension object as defined in java.awt.

public void setSize(double width, double height)

Changes the size of this object to the specified width and height.

Usage:

gobj.setSize(width, height);

Parameters:

width	The new width of the object
height	The new height of the object

public void setVisible(boolean visible)

Sets whether this object is visible.

Usage:

gobj.setVisible(visible);

Parameter:

visible

true to make the object visible, false to hide it

public void translate(double dx, double dy)

Moves the object on the screen using the displacements dx and dy.

Usage:

gobj.translate(dx, dy);

Parameters:

dx	The distance to move the object in the x direction (positive is rightward)
dy	The distance to move the object in the y direction (positive is downward)