Running the World of Drawing, Key Events, and Timer
using Java 1.4 in Eclipse or other full scale IDE

The programs that used the draw.* teachpack in ProfessorJ can be
easily adapted for use with Java 1.4 and any Java IDE, such as
Eclipse, or the command line program invocation.

There are only three minor changes you need to do in programs that 
use the World:

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Building a project that uses the draw.jar teachpack:

- Download the file 'draw.jar' into the eclipse/plugins/ directory

- Start a new Java Project, just as you did in the lab, and import your 
  earlier Maze.java file, or any other file that imported 'draw.*' in
  ProfessorJ

- In the Package Explorer pane highlight the 'default package' for your
  Project

- In the Project menu select Properties

- In the left pane of the Properties for 'your project' select Java Build
  Path

- On the right hand side of the main panel select Add Variable

- In the window that pops up (New Variable Classpath Entry) highlight 
  'draw.jar' and hit 'OK', them hit 'OK' in the main Properties pane.

You can now work on your file that defines the new World.


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The first change in this file is is in the invocation of the method 
bigBang(...) that starts the timer and the world. there are two variants 
of this method, the original one that takes one argument, the speed at 
which the timer ticks should happen. A new variant allows the user 
to choose whether the World should run the timer, monitor the key 
events, and monitor the mouse events (such as mouse clicks, mouse 
moves, etc.) 

The description of the new variant is:

Purpose:
Start the world timer and event monitoring as defined by the arguments

Arguments:
int speed ----- if set to 0.0, do not monitor the timer events
                otherwise use the given speed in miliseconds as  
                the time interval
                assumes the value given is non-negative

boolean key --- if true, monitor the key events

boolean mouse - if true, monitor the mouse events

The three programs DrawingWorld, KeyEventWorld, and TimerWorld illustrate
the use of this variant.


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The second change is in how the program execution is initiated. All Java
Applications start by executing the static method 'main' with the typical
header:

    public static void main(String[] argv){...}

This method takes the place of our Examples class. We can include it in
our TimerWorld or DrawingWorld, or KeyEventWorld class, or in our Blob
class. The method can contain sample data definitions (these act as local
definitions in Scheme) and it will include tests of our methods. It will 
also include the code that will start the World, with the desired event 
monitoring.

To start the World, we need to make an instance of the World and then 
invoke the methods 'start' and 'bigBang' in a manner similar to what we
did in ProfessorJ:

instantiate the TimerWorld:

    TimerWorld w = new TimerWorld(new Blob(new Posn(100, 200), 20));

followed by 

    // start the world, start the timer and key event monitoring
    boolean testWorld = w.start(200,400) 
                     && w.theWorld.bigBang(0.3, w, true, false);

or instantiate the KeyEventWorld:

    // construct an instance of a KeyEventWorld
    KeyEventWorld w = new KeyEventWorld(new Blob(new Posn(100, 200), 20));

followed by 

	// start the world, start the key event monitoring only
	boolean testWorld = w.start(200,400) 
                     && w.theWorld.bigBang(0.0, w, true, false);

or instantiate just the DrawingWorld:

    // make an example of a drawing world
    World dw = new World();

followed by

    // show the world as a canvas of the size 200, 400
    boolean testWorld = dw.start(200, 400);
    
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The rest of the program that uses the draw.ss teachpack should work 
without change.