background.java

j2me polish学习的经典代码

//#condition polish.usePolishGui
/*
 * Created on 04-Jan-2004 at 18:48:09.
 *
 * Copyright (c) 2004-2005 Robert Virkus / Enough Software
 *
 * This file is part of J2ME Polish.
 *
 * J2ME Polish is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * J2ME Polish 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 General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with J2ME Polish; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 * 
 * Commercial licenses are also available, please
 * refer to the accompanying LICENSE.txt or visit
 * http://www.j2mepolish.org for details.
 */
package de.enough.polish.ui;

import javax.microedition.lcdui.Graphics;

import de.enough.polish.io.Serializable;

/**
 * <p>Background is the base class for any backgrounds of widgets or forms.</p>
 *
 * @author Robert Virkus, [e-mail]
 * <pre>
 * history
 *        04-Jan-2004 - rob creation
 * </pre>
 */
public abstract class Background implements Serializable {
	
	/**
	 * Defines the width of this Background.
	 * Usually this is 0, but some backgrounds might have a border included.
	 */
	public int borderWidth;

	/**
	 * Creates a new Background.
	 * The width of this background is set to 0 here.
	 */
	public Background() {
		this.borderWidth = 0;
	}
	
	/**
	 * Animates this background.
	 * Subclasses can override this method to create animations.
	 * 
	 * @return true when this background has been animated.
	 */
	public boolean animate() {
		return false;
	}
	
	/**
	 * Paints this background.
	 * 
	 * @param x the horizontal start point
	 * @param y the vertical start point
	 * @param width the width of the background
	 * @param height the height of the background
	 * @param g the Graphics on which the background should be painted.
	 */
	public abstract void paint( int x, int y, int width, int height, Graphics g );
	
	/**
	 * Releases all (memory intensive) resources such as images or RGB arrays of this background.
	 * The default implementation does not do anything.
	 */
	public void releaseResources() {
		// do nothing
	}

}