41a8f659b99d001c1557a899b06c072e

用J2ME实现的

/*
 *  This program 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.
 *
 *  This program 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 this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *  Copyright(c) 2004 Jordi Martin Perez
*/
package org.piratis.j2me.core;

/**
 * BBox2D: surrounding box with basic square features
 * used by sprite, canvas and so on.
 * 
 * @author		Jordi Mart韓
 * @copyright	Copyright (c) 2004
 * @created 	24-jun-2004
 * @version		$Id: BBox2D.java,v 1.4 2004/07/01 22:14:38 piratis Exp $
 */
public class BBox2D
{
	/**
	 * BBox data. Public visibility to speed up access speed (without the
	 * overhead of a gets methods. 
	 */
	public int x;
	public int y;
	public int width;
	public int height;
	
	/**
	 * Void constructor
	 */
	public BBox2D()
	{
		nullify();
	}
	
	/**
	 * Create a BBox based on another's size
	 * @param other the basis BBox
	 */
	public BBox2D(BBox2D other)
	{
	    this(other.x, other.y, other.width, other.height);
	}
	
	/**
	 * Main constructor
	 * @param x top left corner X
	 * @param y top left corner Y
	 * @param width of the box
	 * @param height of the box
	 */
	public BBox2D(int x, int y, int width, int height)
	{
		super();

		this.x = x;
		this.y = y;
		this.width = width;
		this.height = height;
	}

	/**
	 * Gets the center on the X axis
	 * @return the X-axis center
	 */
	public int getCenterX()
	{
		return this.x + this.width / 2;
	}

	/**
	 * Gets the center on the Y axis
	 * @return the Y-axis center
	 */
	public int getCenterY()
	{
		return this.y + this.height / 2;
	}

	/**
	 * Check if the current BBox collides with another one.
	 * @param other
	 * @return whether the objects collide
	 */
	public boolean collide(BBox2D other)
	{
	    return ((this.x <= (other.x + other.width)) && ((this.x + this.width) >= other.x)
	            && (this.y <= (other.y + other.height)) && ((this.y + this.height) >= other.y));
	}

	/**
	 * Check if this BBox collides with given area
	 * @param oX top-left x-coordinate area corner
	 * @param oY top-left y-coordinate area corner
	 * @param oW area width
	 * @param oH area height
	 * @return whether the area and the BBox collide
	 */
	public boolean collide(int oX, int oY, int oW, int oH)
	{
	    return ((this.x <= (oX + oW)) && ((this.x + this.width) >= oX)
	            && (this.y <= (oY + oH)) && ((this.y + this.height) >= oY));
	}
	
	/**
	 * Merges the current bbox with another, returning the minimal bbox
	 * containing both (overwritting current one)
	 * @param other the merged  bbox
	 * @return the minimal bbox containing both of them
	 */
	public BBox2D merge(BBox2D other)
	{
		// straight cases
		if (this.isVoid())
		{
			this.x = other.x;
			this.y = other.y;
			this.width = other.width;
			this.height = other.height;
		}
		else if (!this.isVoid() && !other.isVoid())
		{
			int maxX = Math.max(this.x + this.width, other.x + other.width);
			int maxY = Math.max(this.y + this.height, other.y + other.height);
			this.x = Math.min(this.x, other.x);
			this.y = Math.min(this.y, other.y);
			this.width = maxX - this.x;
			this.height = maxY - this.y;
		}
		return this;
	}
	
	/**
	 * Checks if the bounding box is not null 0x0
	 * @return
	 */
	public boolean isVoid()
	{
		return ((this.width <= 0) && (this.height <= 0));
	}
	
	/**
	 * @return the area of the sprite (pixel^2)
	 */
	public int getArea()
	{
		return this.width*this.height;
	}

	/**
	 * Voids the current BBox2D
	 */
	public void nullify()
	{
		this.x = this.y = this.width = this.height = 0;
	}
}