acm.graphics
Class GLine

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

public class GLine extends GObject

The GLine class is a graphical object whose appearance consists of a line segment.

[examples forthcoming]

Field Summary

static double

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

Constructor Summary

GLine(double x0, double y0, double x1, double y1)

Method Summary

boolean	contains(double x, double y) Checks to see whether a point is inside the object.
Rectangle	getBounds() Returns the bounding box for this object.
Point	getEndpoint() Returns the endpoint of the line as a Point object.
Point	getOrigin() Returns the coordinates of the initial point in the line.
void	paint(Graphics g) Implements the paint operation for this graphical object.
void	scale(double sx, double sy) Scales the line on the screen by the scale factors sx and sy.
void	setEndpoint(double x, double y) Sets the endpoint of the line to the point (x, y).
void	setOrigin(double x, double y) Sets the origin of the line to the point (x, y), leaving the endpoint unchanged.

Inherited Method Summary

void	addMouseListener(MouseListener listener) Adds a mouse listener to this graphical object. [Inherited from GObject]
void	addMouseMotionListener(MouseMotionListener listener) Adds a mouse motion listener to this graphical object. [Inherited from GObject]
Color	getColor() Returns the color used to display this object. [Inherited from GObject]
boolean	isFilled() Returns whether this object is filled. [Inherited from GObject]
boolean	isVisible() Checks to see whether this object is visible. [Inherited from GObject]
void	moveToBack() Moves this object to the back of the display in stacking order. [Inherited from GObject]
void	moveToFront() Moves this object to the front of the display in stacking order. [Inherited from GObject]
void	removeMouseListener(MouseListener listener) Removes a mouse listener from this graphical object. [Inherited from GObject]
void	removeMouseMotionListener(MouseMotionListener listener) Removes a mouse motion listener from this graphical object. [Inherited from GObject]
void	setColor(Color c) Sets the color used to display this object. [Inherited from GObject]
void	setFilled(boolean fill) Sets whether this object is filled. [Inherited from GObject]
void	setVisible(boolean visible) Sets whether this object is visible. [Inherited from GObject]

Field Detail

public static final double LINE_TOLERANCE

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

Constructor Detail

public GLine(double x0, double y0, double x1, double y1)

Constructs a line segment from its endpoints. The point (x0, y0) defines the origin of the line and the point (x1, y1) defines the endpoint.

Usage:

GLine gpt = new GLine(x0, y0, x1, y1);

Parameters:

x0	The x-coordinate of the origin of the line
y0	The y-coordinate of the origin of the line
x1	The x-coordinate of the endpoint
y1	The y-coordinate of the endpoint

Method Detail

public boolean contains(double x, double y)

Checks to see whether a point is inside the object. For the GLine class, containment is defined to mean that the point is within LINE_TOLERANCE pixels of the line.

Usage:

if (gpt.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 Rectangle getBounds()

Returns the bounding box for this object.

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

public Point getEndpoint()

Returns the endpoint of the line as a Point object.

Usage:	Point pt = gpt.getEndpoint();
Returns:	The coordinates of the endpoint of the line

public Point getOrigin()

Returns the coordinates of the initial point in the line. This method is identical to getLocation and exists only to provide symmetry with setOrigin.

Usage:	Point pt = gpt.getOrigin();
Returns:	The coordinates of the origin of the line

public void paint(Graphics g)

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

public void scale(double sx, double sy)

Scales the line on the screen by the scale factors sx and sy. This method changes only the endpoint of the line, leaving the start of the line fixed.

Usage:

gpt.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 setEndpoint(double x, double y)

Sets the endpoint of the line to the point (x, y). The origin of the line remains unchanged.

Usage:

gpt.setEndpoint(x, y);

Parameters:

x	The new x-coordinate of the endpoint
y	The new y-coordinate of the endpoint

public void setOrigin(double x, double y)

Sets the origin of the line to the point (x, y), leaving the endpoint unchanged. This method is therefore different from setLocation, which moves both components of the line segment.

Usage:

gpt.setOrigin(x, y);

Parameters:

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