acm.graphics
Class GPolygon

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

public class GPolygon extends GObject implements GFillable, GScalable

The GPolygon class is a graphical object whose appearance consists of a polygon.

Constructor Summary

GPolygon()

GPolygon(double x, double y)

GPolygon(GPoint[] points)

Method Summary

void	addArc(double arcWidth, double arcHeight, double start, double sweep) Adds a series of edges to the polygon that simulates the arc specified by the parameters.
void	addEdge(double dx, double dy) Adds an edge to the polygon whose components are given by the displacements dx and dy from the last vertex.
void	addPolarEdge(double r, double theta) Adds an edge to the polygon specified in polar coordinates.
void	addVertex(double x, double y) Adds a vertex at (x, y) relative to the polygon origin.
boolean	contains(double x, double y) Checks to see whether a point is inside the object.
GRectangle	getBounds() Returns the bounding box of this object, which is defined to be the smallest rectangle that covers everything drawn by the figure.
GPoint	getCurrentPoint() Returns the coordinates of the last vertex added to the polygon, or null if the polygon is empty.
Color	getFillColor() Returns the color used to display the filled region of this object.
boolean	isFilled() Returns whether this object is filled.
void	recenter() Recalculates the vertices of the polygon so that they are positioned relative to the geometric center of the object.
void	rotate(double theta) Rotates the polygon around its origin by the angle theta, measured in degrees.
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 polygon by the scale factors sx and sy.
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.

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.
Color	getColor() Returns the color used to display this 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 this 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	setColor(Color color) Sets the color used to display this object.
void	setLocation(GPoint pt) Sets the location of this object to the specified point.
void	setLocation(double x, double y) Sets the location of this object to the point (x, y).
void	setVisible(boolean visible) Sets whether this object is visible.

Constructor Detail

public GPolygon()

Constructs a new empty polygon at the origin.

Usage:

GPolygon gpoly = new GPolygon();

public GPolygon(double x, double y)

Constructs a new empty polygon at (x, y).

Usage:

GPolygon gpoly = new GPolygon(x, y);

Parameters:

x	The x-coordinate of the origin of the polygon
y	The y-coordinate of the origin of the polygon

public GPolygon(GPoint[] points)

Constructs a new polygon from the specified array of GPoint objects. The polygon is automatically marked as complete.

Usage:

GPolygon gpoly = new GPolygon(points);

Parameter:

points

An array of GPoint objects specifying the vertices

Method Detail

public void addArc(double arcWidth, double arcHeight, double start, double sweep)

Adds a series of edges to the polygon that simulates the arc specified by the parameters. The x and y parameters for the arc bounding box are computed implicitly by figuring out what values would place the current vertex at the starting position.

Usage:

gpoly.addArc(arcWidth, arcHeight, start, sweep);

Parameters:

arcWidth	The width of the oval from which the arc is taken
arcHeight	The height of the oval from which the arc is taken
start	The angle at which the arc begins
sweep	The extent of the arc

public void addEdge(double dx, double dy)

Adds an edge to the polygon whose components are given by the displacements dx and dy from the last vertex.

Usage:

gpoly.addEdge(dx, dy);

Parameters:

dx	The x displacement through which the edge moves
dy	The y displacement through which the edge moves

public final void addPolarEdge(double r, double theta)

Adds an edge to the polygon specified in polar coordinates. The length of the edge is given by r, and the edge extends in direction theta, measured in degrees counterclockwise from the +x axis.

Usage:

gpoly.addPolarEdge(r, theta);

Parameters:

r	The length of the edge
theta	The angle at which the edge extends measured in degrees

public void addVertex(double x, double y)

Adds a vertex at (x, y) relative to the polygon origin.

Usage:

gpoly.addVertex(x, y);

Parameters:

x	The x-coordinate of the vertex relative to the polygon origin
y	The y-coordinate of the vertex relative to the polygon origin

public boolean contains(double x, double y)

Checks to see whether a point is inside the object.

Usage:

if (gpoly.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 GRectangle getBounds()

Returns the bounding box of this object, which is defined to be the smallest rectangle that covers everything drawn by the figure.

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

public GPoint getCurrentPoint()

Returns the coordinates of the last vertex added to the polygon, or null if the polygon is empty.

Usage:	GPoint vertex = gpoly.getCurrentPoint();
Returns:	The last vertex added to the polygon, or null if empty

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
Specified by:	getFillColor in interface GFillable

public boolean isFilled()

Returns whether this object is filled.

Usage:	if (gobj.isFilled()) . . .
Returns:	The color used to display the object
Specified by:	isFilled in interface GFillable

public void recenter()

Recalculates the vertices of the polygon so that they are positioned relative to the geometric center of the object. This method allows clients to take a polygon drawn using mouse clicks on the screen and then to reformulate it so that it can be displayed relative to its center.

Usage:

gpoly.recenter();

public void rotate(double theta)

Rotates the polygon around its origin by the angle theta, measured in degrees.

Usage:

gpoly.rotate(theta);

Parameter:

theta

The angle of rotation in degrees counterclockwise

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

Specified by:

scale in interface GScalable

public void scale(double sx, double sy)

Scales the polygon by the scale factors sx and sy.

Usage:

gpoly.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

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

Specified by:

setFillColor in interface GFillable

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

Specified by:

setFilled in interface GFillable