stanford.androidlib.graphics

Class GLine

java.lang.Object

stanford.androidlib.graphics.GObject

stanford.androidlib.graphics.GLine

All Implemented Interfaces:

GScalable

Direct Known Subclasses:

GArrow

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 float	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() Constructs a line segment from its endpoints.
GLine(float x1, float y1) Constructs a line segment from its endpoints.
GLine(float x0, float y0, float x1, float y1) Constructs a line segment from its endpoints.
GLine(GCanvas canvas) Constructs a line segment from its endpoints.
GLine(GCanvas canvas, float x1, float y1) Constructs a line segment from its endpoints.
GLine(GCanvas canvas, float x0, float y0, float x1, float y1) Constructs a line segment from its endpoints.

Method Summary

Modifier and Type	Method and Description
boolean	contains(float x, float 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.
float	getEndX() Returns the end point's x-coordinate.
float	getEndY() Returns the end point's y-coordinate.
GPoint	getStartPoint() Returns the coordinates of the initial point in the line.
float	getStartX() Returns the start point's x-coordinate.
float	getStartY() Returns the start point's y-coordinate.
void	paint(Canvas canvas) Implements the paint operation for this graphical object.
GObject	scale(float sx, float sy) Scales the line on the screen by the scale factors sx and sy.
GLine	setEndPoint(float x, float y) Sets the end point of the line to the point (x, y).
GLine	setStartPoint(float x, float y) Sets the initial point in the line to (x, y), leaving the end point unchanged.

Methods inherited from class stanford.androidlib.graphics.GObject

addTo, addTo, addTo, contains, getBottomY, getCenterX, getCenterY, getColor, getFillColor, getGCanvas, getHeight, getLeftX, getLocation, getPaint, getRightX, getSize, getTopY, getWidth, getX, getY, intersects, isFilled, isVisible, moveBy, moveByPolar, moveTo, moveTo, moveTo, moveToPolar, remove, repaint, scale, sendBackward, sendForward, sendToBack, sendToFront, setBottomY, setBounds, setBounds, setBounds, setCanvas, setColor, setFillColor, setFilled, setGCanvas, setLocation, setLocation, setLocation, setPaint, setRightX, setSize, setSize, setVisible, setX, setY, toString, translate

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface stanford.androidlib.graphics.GScalable

scale

Field Detail

LINE_TOLERANCE

public static final float 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()

Constructs a line segment from its endpoints. The point (0, 0) defines the start of the line and the point (0, 0) defines the end.

Usage:

GLine gline = new GLine();

GLine

public GLine(float x1,
             float y1)

Constructs a line segment from its endpoints. The point (0, 0) defines the start of the line and the point (x1, y1) defines the end.

Parameters:

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

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

Usage:

GLine gline = new GLine(x1, y1);

GLine

public GLine(float x0,
             float y0,
             float x1,
             float 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

Usage:

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

GLine

public GLine(GCanvas canvas)

Constructs a line segment from its endpoints. The point (0, 0) defines the start of the line and the point (0, 0) defines the end.

Usage:

GLine gline = new GLine();

GLine

public GLine(GCanvas canvas,
             float x1,
             float y1)

Constructs a line segment from its endpoints. The point (0, 0) defines the start of the line and the point (x1, y1) defines the end.

Parameters:

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

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

Usage:

GLine gline = new GLine(x1, y1);

GLine

public GLine(GCanvas canvas,
             float x0,
             float y0,
             float x1,
             float 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

Usage:

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

Method Detail

paint

public void paint(Canvas canvas)

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

Specified by:

paint in class GObject

Noshow:

getBounds

public GRectangle getBounds()

Returns the bounding box for this object.

Overrides:

getBounds in class GObject

Returns:

The bounding box for this object

Usage:

GRectangle bounds = gline.getBounds();

setStartPoint

public GLine setStartPoint(float x,
                           float 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

Usage:

gline.setStartPoint(x, y);

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

Usage:

GPoint pt = gline.getStartPoint();

getStartX

public float getStartX()

Returns the start point's x-coordinate. Equivalent to getX().

getStartY

public float getStartY()

Returns the start point's y-coordinate. Equivalent to getY().

getEndX

public float getEndX()

Returns the end point's x-coordinate.

getEndY

public float getEndY()

Returns the end point's y-coordinate.

setEndPoint

public GLine setEndPoint(float x,
                         float 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

Usage:

gline.setEndPoint(x, y);

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

Usage:

GPoint pt = gline.getEndPoint();

scale

public GObject scale(float sx,
                     float 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

Overrides:

scale in class GObject

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

Usage:

gline.scale(sx, sy);

contains

public boolean contains(float x,
                        float 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

Usage:

if (gline.contains(x, y)) . . .