acm.graphics
Class GArc

java.lang.Object
  acm.graphics.GObject
      acm.graphics.GArc

public class GArc
extends GObject
implements GFillable, GScalable

The GArc class is a graphical object whose appearance consists of an arc. If unfilled, the arc is simply a portion of the circumference of an ellipse; if filled, the arc is a pie-shaped wedge connected to the center of the figure.

Field Summary

double

ARC_TOLERANCE This constant defines how close (measured in pixel units) a point has to be to an arc before that point is considered to be "contained" within the arc.

Constructor Summary

GArc(double width, double height, double start, double sweep)

GArc(double x, double y, double width, double height, double start, double sweep)

Method Summary

boolean	contains(double x, double y) Checks to see whether a point is inside the object.
GRectangle	getBounds() Returns the bounding box of the arc.
GPoint	getEndPoint() Returns the point at which the arc ends.
Color	getFillColor() Returns the color used to display the filled region of this object.
GRectangle	getFrameRectangle() Returns the bounds of the GRectangle in which this arc is inscribed.
double	getStartAngle() Returns the starting angle for this GArc object.
GPoint	getStartPoint() Returns the point at which the arc starts.
double	getSweepAngle() Returns the sweep angle for this GArc object.
boolean	isFilled() Returns whether this object is filled.
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	setFillColor(Color color) Sets the color used to display the filled region of this object.
void	setFilled(boolean fill) Sets whether this object is filled.
void	setFrameRectangle(double x, double y, double width, double height) Changes the arc bounds to the specified values.
void	setFrameRectangle(GRectangle bounds) Changes the arc bounds to the values from the specified GRectangle.
void	setStartAngle(double start) Sets the starting angle for this GArc object.
void	setSweepAngle(double sweep) Sets the sweep angle for this GArc object.

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.

Field Detail

public static final double ARC_TOLERANCE

This constant defines how close (measured in pixel units) a point has to be to an arc before that point is considered to be "contained" within the arc.

See Also:

Constant Field Values

Constructor Detail

public GArc(double width, double height, double start, double sweep)

Creates a new GArc object consisting of an elliptical arc located at the point (0, 0). For complete descriptions of the other parameters, see the entry for the GArc constructor that includes explicit x and y parameters.

Usage:

GArc garc = new GArc(width, height, start, sweep);

Parameters:

width	The width of the rectangle in which the arc is inscribed
height	The height of the rectangle in which the arc is inscribed
start	The angle at which the arc begins measured in degrees counterclockwise from the +x axis
sweep	The extent of the arc, measured in degrees counterclockwise

public GArc(double x, double y, double width, double height, double start, double sweep)

Creates a new GArc object consisting of an elliptical arc inscribed in a rectangle located at the point (x, y) with the specified width and height. The start parameter indicates the angle at which the arc begins and is measured in degrees counterclockwise from the +x axis. Thus, a start angle of 0 indicates an arc that begins along the line running eastward from the center (the 3:00 o’clock position), a start angle of 135 begins along the line running northwest, and a start angle of -90 begins along the line running south (the 6:00 o’clock position). The sweep parameter indicates the extent of the arc and is also measured in degrees counterclockwise. A sweep angle of 90 defines a quarter circle extending counterclockwise from the start angle, and a sweep angle of -180 defines a semicircle extending clockwise.

Usage:

GArc garc = new GArc(x, y, width, height, start, sweep);

Parameters:

x	The x-coordinate for the rectangle in which the arc is inscribed
y	The y-coordinate for the rectangle in which the arc is inscribed
width	The width of the rectangle in which the arc is inscribed
height	The height of the rectangle in which the arc is inscribed
start	The angle at which the arc begins measured in degrees counterclockwise from the +x axis
sweep	The extent of the arc, measured in degrees counterclockwise

Method Detail

public boolean contains(double x, double y)

Checks to see whether a point is inside the object. For the GArc class, containment depends on whether the arc is filled. Filled arcs are a wedge in which containment can be defined in a natural way; unfilled arcs are essentially lines, which means that containment is defined to mean that the point is within ARC_TOLERANCE pixels of the arc.

Usage:

if (garc.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

public GRectangle getBounds()

Returns the bounding box of the arc. Note that this method returns the bounds of the visible portion of the arc and will therefore not contain the same values as specified in setFrameRectangle. To obtain the bounds used to describe the Java arc, use getFrameRectangle.

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

Specified by:

getBounds in class GObject

public GPoint getEndPoint()

Returns the point at which the arc ends.

Usage:	GPoint pt = garc.getEndPoint();
Returns:	The point at which the arc ends

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

Specified by:

getFillColor in interface GFillable

public GRectangle getFrameRectangle()

Returns the bounds of the GRectangle in which this arc is inscribed. Note that this is usually different from the bounding box returned by getBounds, which returns the bounding box in which the displayed portion of the arc is contained.

Usage:	GRectangle bounds = garc.getFrameRectangle();
Returns:	The GRectangle in which this arc is inscribed

public double getStartAngle()

Returns the starting angle for this GArc object.

Usage:	double start = garc.getStartAngle();
Returns:	The starting angle for this arc

public GPoint getStartPoint()

Returns the point at which the arc starts.

Usage:	GPoint pt = garc.getStartPoint();
Returns:	The point at which the arc starts

public double getSweepAngle()

Returns the sweep angle for this GArc object.

Usage:	double sweep = garc.getSweepAngle();
Returns:	The sweep angle for this arc

public boolean isFilled()

Returns whether this object is filled.

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

Specified by:

isFilled in interface GFillable

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 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

Specified by:

scale in interface GScalable

public void setFillColor(Color color)

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

Usage:

garc.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:

garc.setFilled(fill);

Parameter:

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

Specified by:

setFilled in interface GFillable

public void setFrameRectangle(double x, double y, double width, double height)

Changes the arc bounds to the specified values.

Usage:

garc.setBounds(x, y, width, height);

Parameters:

x	The x-coordinate for the rectangle in which the arc is inscribed
y	The y-coordinate for the rectangle in which the arc is inscribed
width	The width of the rectangle in which the arc is inscribed
height	The height of the rectangle in which the arc is inscribed

public final void setFrameRectangle(GRectangle bounds)

Changes the arc bounds to the values from the specified GRectangle.

Usage:

garc.setFrameRectangle(bounds);

Parameter:

bounds

A GRectangle specifying the new arc bounds

public void setStartAngle(double start)

Sets the starting angle for this GArc object.

Usage:

garc.setStartAngle(start);

Parameter:

start

The new starting angle

public void setSweepAngle(double sweep)

Sets the sweep angle for this GArc object.

Usage:

garc.setSweepAngle(sweep);

Parameter:

sweep

The new sweep angle