org.piratis.j2me.core.game
Class Engine

java.lang.Object
  org.piratis.j2me.core.game.Engine

All Implemented Interfaces:

java.lang.Runnable

public abstract class Engine

extends java.lang.Object

implements java.lang.Runnable

Default Engine class. All game engines based on J2MEGL must override this one because of the tight binding between this class and the Canvas.

Once started, the engine enters and endlessly loop which won't stop until nextRunLoop return false (good candidate to be overwritten, isn't it?).

A game might contain more than one engine, depending on the status of the game and if it has playable sections/levels which differ among them in great measure, etc.. It is reponsibility of the programmer to stop one and start the other.

Version:

$Id: Engine.java,v 1.5 2004/07/22 16:50:39 piratis Exp $

Author:

Jordi Martín

Field Summary

protected Canvas	canvas Engine and canvas are tightly bound
static int	DEFAULT_FPS Default FPS setting
static int	IS_DOWN
static int	IS_FIRE
static int	IS_GAME_A
static int	IS_GAME_B
static int	IS_GAME_C
static int	IS_GAME_D
static int	IS_LEFT
static int	IS_RIGHT
static int	IS_UP Key status constants
protected LayerManager	layers Where to store all the layers/sprites/tiles

Constructor Summary

Engine(Canvas canvas)
Creates a new Engine.

Engine(Canvas canvas, int fps)
Creates a new Engine.

Method Summary

int	getKeyStates() Gets the states of the game keys.
protected void	initialize(Canvas canvas, int newFps) Initialize method..
protected abstract void	input() Engine's key management method.
protected void	keyPressed(int keyCode) Canvas calls this method upon a key is pressed.
protected void	keyReleased(int keyCode) Canvas call this method upon a key is released.
protected boolean	nextRunLoop() Checks if the run loop needs to continue running (based on engine status)
protected void	paint() Default paint method.
void	run()
protected void	setInitialStatus() Sets the status variables to an initial status
protected void	setRunningStatus() Engine Status to a running status
void	stop() Performs a stop
protected void	waitSomething(long loopStartTime, long interval) Wait method to synchronize work & repainting.
protected abstract void	work() Real engine method that should be implemented in subclasses

Methods inherited from class java.lang.Object

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

Field Detail

IS_UP

public static final int IS_UP

Key status constants

IS_DOWN

public static final int IS_DOWN

IS_LEFT

public static final int IS_LEFT

IS_RIGHT

public static final int IS_RIGHT

IS_FIRE

public static final int IS_FIRE

IS_GAME_A

public static final int IS_GAME_A

IS_GAME_B

public static final int IS_GAME_B

IS_GAME_C

public static final int IS_GAME_C

IS_GAME_D

public static final int IS_GAME_D

DEFAULT_FPS

public static int DEFAULT_FPS

Default FPS setting

canvas

protected Canvas canvas

Engine and canvas are tightly bound

layers

protected LayerManager layers

Where to store all the layers/sprites/tiles

Constructor Detail

Engine

public Engine(Canvas canvas)

Creates a new Engine. FPS are set to the default value.

Parameters:

canvas - the canvas of this engine

Engine

public Engine(Canvas canvas,
              int fps)

Creates a new Engine. FPS is not ensured: the engine/library will do its best to accomplish it!

Parameters:

canvas - the canvas of this engine

fps - desired frames per second refresh rate

Method Detail

run

public void run()

Specified by:

run in interface java.lang.Runnable

See Also:

Runnable.run()

stop

public void stop()

Performs a stop

waitSomething

protected void waitSomething(long loopStartTime,
                             long interval)

Wait method to synchronize work & repainting. Subclasses can override this method to adjust waiting times. It is called at the end of the engine loop.

Parameters:

loopStartTime - the start time of the engine loop

interval - adjusted to the engine/canvas FPS

work

protected abstract void work()

Real engine method that should be implemented in subclasses

input

protected abstract void input()

Engine's key management method. This must be implemented in subclasses in order to react to user key strokes

paint

protected void paint()

Default paint method.

initialize

protected void initialize(Canvas canvas,
                          int newFps)

Initialize method..

setInitialStatus

protected void setInitialStatus()

Sets the status variables to an initial status

nextRunLoop

protected boolean nextRunLoop()

Checks if the run loop needs to continue running (based on engine status)

Returns:

setRunningStatus

protected void setRunningStatus()

Engine Status to a running status

keyPressed

protected void keyPressed(int keyCode)

Canvas calls this method upon a key is pressed. The key pressed status will be automaticaly updated.

Parameters:

keyCode - which key has been pressed

keyReleased

protected void keyReleased(int keyCode)

Canvas call this method upon a key is released. The key pressed status will be automaticaly updated.

Parameters:

keyCode - which key has been released

getKeyStates

public int getKeyStates()

Gets the states of the game keys. The key's status must be checked bitwise.

After calling this method, the key status will be cleared.

Returns: