edu.neu.ccs.pedagogy
Class Turtle

java.lang.Object
  edu.neu.ccs.pedagogy.Turtle

public class Turtle

extends Object

A class to implement turtle graphics that will allow one or more turtle objects to draw in a common BufferedPanel.

Since:

1.1

Version:

2.2

Field Summary

protected boolean	autoRepaint Whether or not repaint occurs after each step.
static Paint	DEFAULT_PAINT The default pen paint.
private static double	DEGREES_TO_RADIANS Degrees to radians conversion.
protected double	direction The turtle direction in degrees measured counterclockwise from the positive horizontal axis.
private Line2D	line The line to draw.
static int	MINIMUM_SIZE The minimum size of the common turtle buffered panel.
(package private) GeneralPath	path The path to outline the turtle triangle shape.
static int	PEN_DOWN Turtle pen state: pen down.
static int	PEN_UP Turtle pen state: pen up.
protected Paint	penPaint The turtle pen paint.
protected int	penState The turtle pen state.
private Point2D	point1 Endpoint 1 of the line.
private Point2D	point2 Endpoint 2 of the line.
static int	PREFERRED_SIZE The preferred size of the common turtle buffered panel.
protected boolean	showTurtle Whether or not the turtle triangle is visible.
protected static AffineTransform	transform The affine transform used to scale all turtle drawing.
protected static BufferedPanel	turtleBufferPanel The common buffered panel for all turtle graphics.
protected static int	turtleBufferPanelSize The size of the common turtle buffered panel.
protected static Vector	turtleList The list of turtle objects that have been created.
protected double	xPosition The turtle x position.
protected double	yPosition The turtle y position.

Constructor Summary

Turtle()
The default turtle constructor creates the turtle buffered panel if that buffered panel has not been created by an earlier turtle and then adds this turtle to the list of all turtles.

Method Summary

static void	clear() Clear the common turtle buffered panel and repaint.
protected void	drawTurtle(Graphics2D g2) Draw the turtle triangle at the current turtle position in the current turtle direction.
boolean	getAutoRepaint() Return the current auto repaint setting.
double	getDirection() Return the turtle direction.
Paint	getPaint() Return the turtle pen paint.
int	getPenState() Return the turtle pen state.
Point2D	getPosition() Return the turtle position.
static BufferedImage	getTurtleBuffer() Return the buffer in the common turtle buffered panel.
static Graphics2D	getTurtleBufferGraphics() Return the graphics context for the common turtle buffered panel.
static BufferedPanel	getTurtleBufferPanel() Create and return the common buffered panel for turtle graphics.
static int	getTurtleBufferPanelSize() Return the size of the common buffered panel for turtle graphics.
static Turtle[]	getTurtles() Return an array of all turtles that have been created.
double	getX() Return the turtle x position.
double	getY() Return the turtle y position.
static void	hideAllTurtles() Hide all turtle triangles.
void	hideTurtle() Hide the turtle triangle.
boolean	isVisible() Return whether or not the turtle triangle is visible.
static void	repaint() Repaint the common turtle buffered panel.
void	reset() Reset the turtle to its default initial state and then repaint.
static void	selfTest() A simple self test.
void	setAutoRepaint(boolean enabled) Set auto repaint, that is, whether or not to repaint after each step, to the given value.
static void	setCoordinatesViaBounds(Rectangle2D world) Set the coordinate system in the common turtle buffered panel using the given bounds in the world coordinate system to define the affine coordinate transformation.
static void	setCoordinatesViaBounds(Rectangle2D world, int inset) Set the coordinate system in the common turtle buffered panel using the given bounds in the world coordinate system and the given image inset to define the affine coordinate transformation.
void	setDirection(double direction) Set the turtle direction in degrees counterclockwise from the positive horizontal axis.
void	setPaint(int r, int g, int b) Set the turtle pen paint via r,g,b components.
void	setPaint(int r, int g, int b, int alpha) Set the turtle pen paint via r, g, b, alpha components.
void	setPaint(Paint paint) Set the turtle pen paint.
void	setPenState(int penState) Set the turtle pen state.
void	setPosition(double x, double y) Set the turtle position.
void	setPosition(Point2D position) Set the turtle position.
static void	setTurtleBufferPanelSize(int size) Set the size of the common buffered panel for turtle graphics (this must be called before the buffered panel is created).
void	setVisible(boolean visible) Show or hide the turtle triangle using the given parameter to decide.
static void	showAllTurtles() Show all turtle triangles.
void	showTurtle() Show the turtle triangle.
void	step(double distance) Move the turtle from its current position by the given distance in its current direction and if the current pen state is PEN_DOWN then draw a line using the current pen paint.
void	turn(double angle) Increment the turtle direction by the given angle in degrees.
static void	useCenterCoordinates() Use a coordinate system with the origin at the center of the common turtle buffered panel and with x increasing rightwards and y increasing upwards.
static void	useCornerCoordinates() Use a coordinate system with the origin at the lower left corner of the common turtle buffered panel and with x increasing rightwards and y increasing upwards.

Methods inherited from class java.lang.Object

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

Field Detail

MINIMUM_SIZE

public static final int MINIMUM_SIZE

The minimum size of the common turtle buffered panel.

See Also:

Constant Field Values

PREFERRED_SIZE

public static final int PREFERRED_SIZE

The preferred size of the common turtle buffered panel.

See Also:

Constant Field Values

DEFAULT_PAINT

public static final Paint DEFAULT_PAINT

The default pen paint.

PEN_UP

public static final int PEN_UP

Turtle pen state: pen up.

See Also:

Constant Field Values

PEN_DOWN

public static final int PEN_DOWN

Turtle pen state: pen down.

See Also:

Constant Field Values

DEGREES_TO_RADIANS

private static final double DEGREES_TO_RADIANS

Degrees to radians conversion.

See Also:

Constant Field Values

turtleBufferPanel

protected static BufferedPanel turtleBufferPanel

The common buffered panel for all turtle graphics.

turtleBufferPanelSize

protected static int turtleBufferPanelSize

The size of the common turtle buffered panel.

transform

protected static AffineTransform transform

The affine transform used to scale all turtle drawing.

turtleList

protected static Vector turtleList

The list of turtle objects that have been created.

xPosition

protected double xPosition

The turtle x position.

yPosition

protected double yPosition

The turtle y position.

direction

protected double direction

The turtle direction in degrees measured counterclockwise from the positive horizontal axis.

penPaint

protected Paint penPaint

The turtle pen paint.

penState

protected int penState

The turtle pen state.

showTurtle

protected boolean showTurtle

Whether or not the turtle triangle is visible.

autoRepaint

protected boolean autoRepaint

Whether or not repaint occurs after each step.

line

private Line2D line

The line to draw.

point1

private Point2D point1

Endpoint 1 of the line.

point2

private Point2D point2

Endpoint 2 of the line.

path

GeneralPath path

The path to outline the turtle triangle shape.

Constructor Detail

Turtle

public Turtle()

The default turtle constructor creates the turtle buffered panel if that buffered panel has not been created by an earlier turtle and then adds this turtle to the list of all turtles. The default turtle settings are:

• x position = 0
• y position = 0
• direction = 0
• pen paint = Color.black
• pen state = PEN_DOWN
• show turtle = true
• auto repaint = true

Method Detail

setTurtleBufferPanelSize

public static void setTurtleBufferPanelSize(int size)

Set the size of the common buffered panel for turtle graphics (this must be called before the buffered panel is created).

Parameters:

size - the new turtle buffered panel size

See Also:

getTurtleBufferPanel(), getTurtleBufferPanelSize()

getTurtleBufferPanelSize

public static int getTurtleBufferPanelSize()

Return the size of the common buffered panel for turtle graphics.

See Also:

getTurtleBufferPanel(), setTurtleBufferPanelSize(int)

getTurtleBufferPanel

public static BufferedPanel getTurtleBufferPanel()

Create and return the common buffered panel for turtle graphics.

See Also:

setTurtleBufferPanelSize(int), getTurtleBufferPanelSize()

useCenterCoordinates

public static void useCenterCoordinates()

Use a coordinate system with the origin at the center of the common turtle buffered panel and with x increasing rightwards and y increasing upwards.

See Also:

useCornerCoordinates(), setCoordinatesViaBounds(Rectangle2D), setCoordinatesViaBounds(Rectangle2D, int)

useCornerCoordinates

public static void useCornerCoordinates()

Use a coordinate system with the origin at the lower left corner of the common turtle buffered panel and with x increasing rightwards and y increasing upwards.

See Also:

useCenterCoordinates(), setCoordinatesViaBounds(Rectangle2D), setCoordinatesViaBounds(Rectangle2D, int)

setCoordinatesViaBounds

public static void setCoordinatesViaBounds(Rectangle2D world)

Set the coordinate system in the common turtle buffered panel using the given bounds in the world coordinate system to define the affine coordinate transformation.

Parameters:

world - the bounds in world coordinates

See Also:

useCenterCoordinates(), useCornerCoordinates(), setCoordinatesViaBounds(Rectangle2D, int)

setCoordinatesViaBounds

public static void setCoordinatesViaBounds(Rectangle2D world,
                                           int inset)

Set the coordinate system in the common turtle buffered panel using the given bounds in the world coordinate system and the given image inset to define the affine coordinate transformation.

Parameters:

world - the bounds in world coordinates

inset - the inset of the turtle drawing within the image

See Also:

useCenterCoordinates(), useCornerCoordinates(), setCoordinatesViaBounds(Rectangle2D)

getTurtleBufferGraphics

public static Graphics2D getTurtleBufferGraphics()

Return the graphics context for the common turtle buffered panel.

getTurtleBuffer

public static BufferedImage getTurtleBuffer()

Return the buffer in the common turtle buffered panel.

clear

public static void clear()

Clear the common turtle buffered panel and repaint.

repaint

public static void repaint()

Repaint the common turtle buffered panel.

getTurtles

public static Turtle[] getTurtles()

Return an array of all turtles that have been created. If none have been created then the array returned will have zero elements.

showAllTurtles

public static void showAllTurtles()

Show all turtle triangles.

hideAllTurtles

public static void hideAllTurtles()

Hide all turtle triangles.

step

public void step(double distance)

Move the turtle from its current position by the given distance in its current direction and if the current pen state is PEN_DOWN then draw a line using the current pen paint.

The default is to set auto repaint to true. This will give immediate feedback for each step call but will be slower if lots of step calls are made.

To improve the speed of turtle graphics at the expense of immediate feedback, make the call on a Turtle named T:

• T.setAutoRepaint(false);

Then, to repaint the turtle buffered panel when the turtle drawing is complete, make the static call:

• Turtle.repaint();

This design dramatically improves graphics performance.

Parameters:

distance - the distance to step

See Also:

setAutoRepaint(boolean), getAutoRepaint()

turn

public void turn(double angle)

Increment the turtle direction by the given angle in degrees.

Parameters:

angle - the angle in degrees used to increment the direction

See Also:

setDirection(double)

showTurtle

public void showTurtle()

Show the turtle triangle.

See Also:

hideTurtle(), setVisible(boolean), isVisible()

hideTurtle

public void hideTurtle()

Hide the turtle triangle.

See Also:

showTurtle(), setVisible(boolean), isVisible()

setVisible

public void setVisible(boolean visible)

Show or hide the turtle triangle using the given parameter to decide.

Parameters:

visible - if true then show the turtle otherwise hide it

See Also:

showTurtle(), hideTurtle(), isVisible()

isVisible

public boolean isVisible()

Return whether or not the turtle triangle is visible.

See Also:

showTurtle(), hideTurtle(), setVisible(boolean)

setPosition

public void setPosition(double x,
                        double y)

Set the turtle position.

Parameters:

x - the turtle x position

y - the turtle y position

See Also:

setPosition(Point2D), getPosition(), getX(), getY()

setPosition

public void setPosition(Point2D position)

Set the turtle position.

Parameters:

position - the turtle position

See Also:

setPosition(double, double), getPosition(), getX(), getY()

getPosition

public Point2D getPosition()

Return the turtle position.

See Also:

setPosition(double, double), setPosition(Point2D), getX(), getY()

getX

public double getX()

Return the turtle x position.

See Also:

setPosition(double, double), setPosition(Point2D), getPosition(), getY()

getY

public double getY()

Return the turtle y position.

See Also:

setPosition(double, double), setPosition(Point2D), getPosition(), getX()

setDirection

public void setDirection(double direction)

Set the turtle direction in degrees counterclockwise from the positive horizontal axis.

Parameters:

direction - the new turtle direction

See Also:

getDirection(), turn(double)

getDirection

public double getDirection()

Return the turtle direction.

See Also:

setDirection(double)

setPaint

public void setPaint(Paint paint)

Set the turtle pen paint.

Parameters:

paint - the paint to use for drawing this turtle

See Also:

getPaint(), setPaint(int, int, int), setPaint(int, int, int, int)

setPaint

public void setPaint(int r,
                     int g,
                     int b)

Set the turtle pen paint via r,g,b components.

Parameters:

r - the red component of the Color to be used to paint

g - the green component of the Color to be used to paint

b - the blue component of the Color to be used to paint

See Also:

getPaint(), setPaint(Paint), setPaint(int, int, int, int)

setPaint

public void setPaint(int r,
                     int g,
                     int b,
                     int alpha)

Set the turtle pen paint via r, g, b, alpha components.

Parameters:

r - the red component of the Color to be used to paint

g - the green component of the Color to be used to paint

b - the blue component of the Color to be used to paint

alpha - the alpha component of the Color to be used to paint

See Also:

getPaint(), setPaint(Paint), setPaint(int, int, int)

getPaint

public Paint getPaint()

Return the turtle pen paint.

See Also:

setPaint(Paint)

setPenState

public void setPenState(int penState)

Set the turtle pen state.

Parameters:

penState - the pen state: PEN_UP or PEN_DOWN

See Also:

getPenState(), PEN_UP, PEN_DOWN

getPenState

public int getPenState()

Return the turtle pen state.

See Also:

setPenState(int), PEN_UP, PEN_DOWN

setAutoRepaint

public void setAutoRepaint(boolean enabled)

Set auto repaint, that is, whether or not to repaint after each step, to the given value.

Parameters:

enabled - the new auto repaint setting

See Also:

getAutoRepaint(), step(double)

getAutoRepaint

public boolean getAutoRepaint()

Return the current auto repaint setting.

See Also:

setAutoRepaint(boolean), step(double)

reset

public void reset()

Reset the turtle to its default initial state and then repaint. The default settings are:

• x position = 0
• y position = 0
• direction = 0
• pen paint = Color.black
• pen state = PEN_DOWN
• show turtle = true
• auto repaint = true

drawTurtle

protected void drawTurtle(Graphics2D g2)

Draw the turtle triangle at the current turtle position in the current turtle direction.

This method is called by the paintOver method of the common turtle buffered panel during repaint actions.

selfTest

public static void selfTest()

A simple self test.