world
Class VoidWorld

java.lang.Object
  world.VoidWorld

Direct Known Subclasses:

MousePointsVoidWorld, StateExamples, StopTest.MousePointsWorld, VoidWorldInteractions

public abstract class VoidWorld
extends java.lang.Object

A Class representing an imperative World and the related methods for drawing the world and handling various events. In order to implement a functioning World you must extend this class, and implement an onDraw method. Other handler methods (tickRate, onTick, onMouse, onKey, onRelease, stopWhen, and lastScene) are optional, and can be overridden to add new functionality.

See the individual methods for detailed documentation.

Extending VoidWorld

Below is a simple example of a VoidWorld that adds a new point at each mouse click. The world contains a Scene and a new Circle is placed for each "button-down" event received.

   
        import image.*;
        import world.VoidWorld;
        
        public class MousePointsVoidWorld extends VoidWorld{
            // Simple Main Program
            public static void main(String[] args)
            { new MousePointsVoidWorld().bigBang(); }
            
            // The inner Scene
            Scene scene = new EmptyScene(200, 200);
        
            // Create a new World
            MousePointsVoidWorld(){}
            
            // Draw by returning the inner Scene
            public Scene onDraw(){ return this.scene; }
        
            // On a mouse click add a circle to the inner Scene
            public void onMouse(int x, int y, String me){
                if(me.equals("button-down")){
                    this.scene = this.scene.placeImage(
                                     new Circle(20, "solid", "red")
                                           .overlay(new Circle(20, "outline", "black")), x, y);
                }
            }
        }
 

After a few mouse clicks, the window will look something like this:

Field Summary

static double	DEFAULT_TICK_RATE Default Tick rate for the world: ~33 frames per second
static java.lang.String	KEY_ARROW_DOWN Key arrow-down event String
static java.lang.String	KEY_ARROW_LEFT Key arrow-left event String
static java.lang.String	KEY_ARROW_RIGHT Key arrow-right event String
static java.lang.String	KEY_ARROW_UP Key arrow-up event String
static java.lang.String	MOUSE_DOWN Mouse down (button-down) event String
static java.lang.String	MOUSE_DRAG Mouse down & move (drag) event String
static java.lang.String	MOUSE_ENTER Mouse window enter (enter) event String
static java.lang.String	MOUSE_LEAVE Mouse window leave (leave) event String
static java.lang.String	MOUSE_MOVE Mouse motion (move) event String
static java.lang.String	MOUSE_UP Mouse up (button-up) event String

Constructor Summary

VoidWorld()

Method Summary

VoidWorld	bigBang() Kick off the interaction/animation.
boolean	equals(java.lang.Object o) Make sure that changes are redrawn every time
Scene	lastScene() Returns the Scene that should be displayed when the interaction/animation completes (stopWhen() returns true).
abstract Scene	onDraw() Return a visualization of this VoidWorld as a Scene.
void	onKey(java.lang.String event) Change this VoidWorld when a key event is triggered.
void	onMouse(int x, int y, java.lang.String event) Change this VoidWorld when a mouse event is triggered.
void	onRelease(java.lang.String event) Change this VoidWorld when a key is released.
void	onTick() Change this VoidWorld based on the Tick of the clock.
boolean	stopWhen() Determine if the World/interaction/animation should be stopped.
double	tickRate() Return the tick rate for this VoidWorld in seconds.

Methods inherited from class java.lang.Object

getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT_TICK_RATE

public static double DEFAULT_TICK_RATE

Default Tick rate for the world: ~33 frames per second

MOUSE_DOWN

public static java.lang.String MOUSE_DOWN

Mouse down (button-down) event String

MOUSE_UP

public static java.lang.String MOUSE_UP

Mouse up (button-up) event String

MOUSE_ENTER

public static java.lang.String MOUSE_ENTER

Mouse window enter (enter) event String

MOUSE_LEAVE

public static java.lang.String MOUSE_LEAVE

Mouse window leave (leave) event String

MOUSE_MOVE

public static java.lang.String MOUSE_MOVE

Mouse motion (move) event String

MOUSE_DRAG

public static java.lang.String MOUSE_DRAG

Mouse down & move (drag) event String

KEY_ARROW_UP

public static java.lang.String KEY_ARROW_UP

Key arrow-up event String

KEY_ARROW_DOWN

public static java.lang.String KEY_ARROW_DOWN

Key arrow-down event String

KEY_ARROW_LEFT

public static java.lang.String KEY_ARROW_LEFT

Key arrow-left event String

KEY_ARROW_RIGHT

public static java.lang.String KEY_ARROW_RIGHT

Key arrow-right event String

Constructor Detail

VoidWorld

public VoidWorld()

Method Detail

onDraw

public abstract Scene onDraw()

Return a visualization of this VoidWorld as a Scene. See EmptyScene, Scene.placeImage(Image, int, int), and Scene.addLine(int, int, int, int, String) for documentation on constructing Scenes

tickRate

public double tickRate()

Return the tick rate for this VoidWorld in seconds. For example, 0.5 means two ticks per second. The rate is only accessed when bigBang() is initially called and the window is created.

onTick

public void onTick()

Change this VoidWorld based on the Tick of the clock. This method is called to update the VoidWorld on each clock tick.

onMouse

public void onMouse(int x,
                    int y,
                    java.lang.String event)

Change this VoidWorld when a mouse event is triggered. x and y are the location of the event in the window, and event is a String that describes what kind of event occurred.

Possible Mouse Events

"button-down" :	The user presses a mouse button in the VoidWorld window
"button-up" :	The user releases a mouse button in the VoidWorld window
"move" :	The user moves the mouse in the VoidWorld window
"drag" :	The user holds a mouse button and moves the mouse in the VoidWorld window
"enter" :	The user moves the mouse in-to the VoidWorld window
"leave" :	The user moves the mouse out-of the VoidWorld window

onKey

public void onKey(java.lang.String event)

Change this VoidWorld when a key event is triggered. The given event is a String that describes which key was pressed.

Special Key

"up" :	The user presses the up-arrow key
"down" :	The user presses the down-arrow key
"left" :	The user presses the left-arrow key
"right" :	The user presses the right-arrow key

Other keys generate a single character String that represents the key pressed. For example, Pressing the B key on the keyboard generates "b" as an event. If the shift key is held while pressing B then "B" is generated.

onRelease

public void onRelease(java.lang.String event)

Change this VoidWorld when a key is released. The given event is a String that describes which key was released.

Special Keys

"up" :	The user presses the up-arrow key
"down" :	The user presses the down-arrow key
"left" :	The user presses the left-arrow key
"right" :	The user presses the right-arrow key

Other keys generate a single character String that represents the key released. For example, Pressing then releasing the B key on the keyboard generates "b" as an onKey event and again as an onRelease event. If the shift key is held while pressing/releasing B then "B" is generated.

stopWhen

public boolean stopWhen()

Determine if the World/interaction/animation should be stopped. Returning a value of true discontinues all events (mouse, key, ticks) and causes lastScene() to be used to draw the final Scene.

lastScene

public Scene lastScene()

Returns the Scene that should be displayed when the interaction/animation completes (stopWhen() returns true).

bigBang

public VoidWorld bigBang()

Kick off the interaction/animation. This method returns the final state of the world after the user closes the World window.

equals

public boolean equals(java.lang.Object o)

Make sure that changes are redrawn every time

Overrides:

equals in class java.lang.Object