Stepper

Class Stepper

java.lang.Object
  java.lang.ThreadGroup
      Stepper

public class Stepper
extends java.lang.ThreadGroup

The Stepper class can be attached to the turtle Canvas to control how fast things happen. It can move the turtles one step at a time, or set steps to happen continuously with a specified delay for each. There is only one Stepper instantiated; it can be retrieved with getStepper(). The Stepper manages a single "run" through the commands in Controller.run(). The run can be paused, stopped, restarted, or advanced a step at a time by various Stepper methods. There is only one run active a any time; any old runs are terminated when a new run begins.

Version:: 6/3/05
Author:: Russell Zahniser

Field Summary

Fields inherited from class java.lang.ThreadGroup

Method Summary
`void`	`checkRun()` Check to make sure that you aren't part of a dead run.
`void`	`didStep()` End a step of the run.
`void`	`endRun()` Stop the current run, without waiting for it to finish.
`Canvas`	`getCanvas()` Return the canvas that this Stepper is attached to.
`static Stepper`	`getStepper()` Return the Stepper.
`boolean`	`isStopped()` Check whether the stepper is stopped.
`void`	`newRun()` Make a new run.
`void`	`pause()` Pause the current run.
`void`	`restart()` Restart the current run, if it was paused.
`void`	`setScale(double setting)` The applet should call this when it wants to change the scale of the canvas.
`void`	`setSpeed(int speed)` Set the speed for the run.
`void`	`step()` Move the current run forward one step.

Methods inherited from class java.lang.ThreadGroup

activeCount, activeGroupCount, allowThreadSuspension, checkAccess, destroy, enumerate, enumerate, enumerate, enumerate, getMaxPriority, getName, getParent, interrupt, isDaemon, isDestroyed, list, parentOf, resume, setDaemon, setMaxPriority, stop, suspend, toString, uncaughtException

Methods inherited from class java.lang.Object

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

Method Detail

checkRun

public void checkRun()

Check to make sure that you aren't part of a dead run. A Turtle should check this before it does anything so that it will not accidentally draw onto the new Canvas.

didStep

public void didStep()

End a step of the run. A turtle should access this through Turtle.done(). This will pause the run for the appropriate amount of time, or have it wait for the run to start up again.

endRun

public void endRun()

Stop the current run, without waiting for it to finish. This also clears the canvas.

getCanvas

public Canvas getCanvas()

Return the canvas that this Stepper is attached to.

Returns:: the Canvas.

getStepper

public static Stepper getStepper()

Return the Stepper.

Returns:: the Stepper

isStopped

public boolean isStopped()

Check whether the stepper is stopped.

Returns:: true if the current run is paused.

newRun

public void newRun()

Make a new run. Any old run is ended.

pause

public void pause()

Pause the current run. It can be restarted with restart().

restart

public void restart()

Restart the current run, if it was paused.

setScale

public void setScale(double setting)

The applet should call this when it wants to change the scale of the canvas. This affects how big things are drawn, not what the turtles' actual coordinates are.

Parameters:: setting - How big to draw, from 0 (tiny) to 4 (HUGE)

setSpeed

public void setSpeed(int speed)

Set the speed for the run.

Parameters:: speed - Length of pause per step, from 0 (very fast) to 6 (slow)

step

public void step()

Move the current run forward one step. It will then be paused.