SWT2Dutil.java

/*******************************************************************************
* Copyright (c) 2004 Chengdong Li : cdli@ccs.uky.edu
* All rights reserved. This program and the accompanying materials 
* are made available under the terms of the Common Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/cpl-v10.html
*******************************************************************************/
package jqian.slicer.view;

import java.awt.geom.AffineTransform;
import java.awt.geom.Point2D;

import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;


/**
 * Utility for Java2d transform
 *  
 * @author Chengdong Li: cli4@uky.edu
 * 
 */
public class SWT2Dutil {

	/**
	 * Given an arbitrary rectangle, get the rectangle with the given transform.
	 * The result rectangle is positive width and positive height.
	 * @param af AffineTransform
	 * @param src source rectangle
	 * @return rectangle after transform with positive width and height
	 */
	public static Rectangle transformRect(AffineTransform af, Rectangle src){
		Rectangle dest= new Rectangle(0,0,0,0);
		src=absRect(src);
		Point p1=new Point(src.x,src.y);
		p1=transformPoint(af,p1);
		dest.x=p1.x; dest.y=p1.y;
		dest.width=(int)(src.width*af.getScaleX());
		dest.height=(int)(src.height*af.getScaleY());
		return dest;
	}

	/**
	 * Given an arbitrary rectangle, get the rectangle with the inverse given transform.
	 * The result rectangle is positive width and positive height.
	 * @param af AffineTransform
	 * @param src source rectangle
	 * @return rectangle after transform with positive width and height
	 */
	public static Rectangle inverseTransformRect(AffineTransform af, Rectangle src){
		Rectangle dest= new Rectangle(0,0,0,0);
		src=absRect(src);
		Point p1=new Point(src.x,src.y);
		p1=inverseTransformPoint(af,p1);
		dest.x=p1.x; dest.y=p1.y;
		dest.width=(int)(src.width/af.getScaleX());
		dest.height=(int)(src.height/af.getScaleY());
		return dest;
	}

	/**
	 * Given an arbitrary point, get the point with the given transform.
	 * @param af affine transform
	 * @param pt point to be transformed
	 * @return point after tranform
	 */
	public static Point transformPoint(AffineTransform af, Point pt) {
		Point2D src = new Point2D.Float(pt.x, pt.y);
		Point2D dest= af.transform(src, null);
		Point point=new Point((int)Math.floor(dest.getX()), (int)Math.floor(dest.getY()));
		return point;
	}
	
	/**
	 * Given an arbitrary point, get the point with the inverse given transform.
	 * @param af AffineTransform
	 * @param pt source point
	 * @return point after transform
	 */
	public static Point inverseTransformPoint(AffineTransform af, Point pt){
		Point2D src=new Point2D.Float(pt.x,pt.y);
		try{
			Point2D dest= af.inverseTransform(src, null);
			return new Point((int)Math.floor(dest.getX()), (int)Math.floor(dest.getY()));
		}catch (Exception e){
			e.printStackTrace();
			return new Point(0,0);
		}
	}

	/**
	 * Given arbitrary rectangle, return a rectangle with upper-left 
	 * start and positive width and height.
	 * @param src source rectangle
	 * @return result rectangle with positive width and height
	 */
	public static Rectangle absRect(Rectangle src){
		Rectangle dest= new Rectangle(0,0,0,0);
		if(src.width<0) { dest.x=src.x+src.width+1; dest.width=-src.width; } 
		else{ dest.x=src.x; dest.width=src.width; }
		if(src.height<0) { dest.y=src.y+src.height+1; dest.height=-src.height; } 
		else{ dest.y=src.y; dest.height=src.height; }
		return dest;
	}
}