acm.graphics

Class GLine

java.lang.Object

acm.graphics.GObject

acm.graphics.GLine

All Implemented Interfaces:

GScalable, java.lang.Cloneable

public class GLine
extends GObject
implements GScalable

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

Field Summary

Fields

Modifier and Type	Field and Description
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

Constructors

Constructor and Description
GLine(double x0, double y0, double x1, double y1) Constructs a line segment from its endpoints.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	contains(double x, double y) Checks to see whether a point is inside the object.
GRectangle	getBounds() Returns the bounding box for this object.
GPoint	getEndPoint() Returns the end point of the line as a GPoint object.
GPoint	getStartPoint() Returns the coordinates of the initial point in the line.
void	paint(java.awt.Graphics g) Implements the paint operation for this graphical object.
java.lang.String	paramString() Returns a string indicating the parameters of this 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 line on the screen by the scale factors sx and sy.
void	setEndPoint(double x, double y) Sets the end point of the line to the point (x, y).
void	setStartPoint(double x, double y) Sets the initial point in the line to (x, y), leaving the end point unchanged.

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

Field Detail

LINE_TOLERANCE

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.

See Also:

Constant Field Values

Constructor Detail

GLine

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

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

Parameters:

x0 - The x-coordinate of the start of the line

y0 - The y-coordinate of the start of the line

x1 - The x-coordinate of the end of the line

y1 - The y-coordinate of the end of the line

Method Detail

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

getBounds

public GRectangle getBounds()

Returns the bounding box for this object.

Specified by:

getBounds in class GObject

Returns:

The bounding box for this object

setStartPoint

public void setStartPoint(double x,
                 double y)

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

Parameters:

x - The new x-coordinate of the origin

y - The new y-coordinate of the origin

getStartPoint

public GPoint getStartPoint()

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

Returns:

The coordinates of the origin of the line

setEndPoint

public void setEndPoint(double x,
               double y)

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

Parameters:

x - The new x-coordinate of the end point

y - The new y-coordinate of the end point

getEndPoint

public GPoint getEndPoint()

Returns the end point of the line as a GPoint object.

Returns:

The coordinates of the end point of the line

scale

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 end point of the line, leaving the start of the line fixed.

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

contains

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.

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

paramString

public java.lang.String paramString()

Returns a string indicating the parameters of this object.