animation.java

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/*
 * Fire (Flexible Interface Rendering Engine) is a set of graphics widgets for creating GUIs for j2me applications. 
 * Copyright (C) 2006-2008 Bluevibe (www.bluevibe.net)
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 * 
 */

package gr.fire.core;

import javax.microedition.lcdui.Graphics;
import javax.microedition.lcdui.Image;


/**
 * 
 * Animation are either used as transitions effects (used when the state of a Container changes) 
 * or as Animations inside a component.
 * <br/> 
 * A transition effect can be displayed for example when a component is added or 
 * removed from the Container or when the container is made visible or disabled etc.
 * The transition effect will be triggered if there is a 
 * Animation instance associated with the transition the container is going through.
 * <br/>
 * An animation inside a Component can be for example the movement of the dials of an AnalogClock component.
 * This type of animation is continious (i.e. it will not complete).
 * <br/>
 * An animation is confined inside its owner. It is not allowed to paint outside the 
 * clipping rectangle defined by owner.x,owner.y,owner.width,owner.height.
 * 
 * @author padeler
 *
 */
public abstract class Animation
{
	private static Image offscreen;

	protected Image getOffscreen()
	{
		if(offscreen==null)
		{
			FireScreen screen = FireScreen.getScreen();
			System.out.println("Creating animation offscreen "+screen.getWidth()+"/"+screen.getHeight());
			offscreen = Image.createImage(screen.getWidth(),screen.getHeight());
			
		}
		return offscreen;
	}
	/**
	 * 
	 * An animation is running when it has not yet reached its final state.
	 * This function should not alter the state of the animation and should return fast.
	 * 
	 * @return true, if this Animation is running. 
	 * 
	 * @see  Animation#step()
	 */
	public abstract boolean isRunning();
	
	/**
	 * Setups this animation for the given owner,triger and properties.
	 * @param owner
	 * @param trigger
	 * @param properties
	 * @throws IllegalArgumentException if owner or trigger are null.
	 */
	public abstract void setup(Component owner, Component trigger, Object properties);
	
	/**
	 * Causes this animation to move to its next frame. 
	 * This method should return as fast as possible.
	 *  
	 * @return true, if the animation needs to be re-drawn on the screen. false otherwise.
	 */
	public abstract boolean step();
	
	
	/**
	 * Moves the animation to its last state. 
	 * Subsequent calls to getCurrentFrame() should return the final frame of the animation. 
	 */
	public abstract void stop();
	
	/**
	 * 
	 * @return an image containing the current frame of this effect. 
	 */
	public abstract void paint(Graphics g);
		
	
	public abstract Component getOwner();
	public abstract Component getTrigger();
	public abstract Object getProperties();
	
}