TwistFilter.java

/* 
 * HaoRan ImageFilter Classes v0.3
 * Copyright (C) 2012 Zhenjun Dai
 *
 * 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.
 */

package com.marshalchen.common.uimodule.ImageFilter.Distort;

import com.marshalchen.common.uimodule.ImageFilter.IImageFilter;

public class TwistFilter extends BilinearDistort{
	double   _twist ;
    double   _size ;
    double   _offsetX ;
    double   _offsetY ;
	 
    public TwistFilter(int amount, int size){
    	this(amount, size, 0, 0);
    }
    public TwistFilter (int amount, int size, double offsetX, double offsetY)
    {
        amount = -amount ;
        _twist = amount * amount * ((amount > 0) ? 1 : -1) ;

        _size = 1.0 / (Function.FClamp(size, 1, 200) / 100.0) ;
        _offsetX = Function.FClampDouble(offsetX, -2.0, 2.0) ;
        _offsetY = Function.FClampDouble(offsetY, -2.0, 2.0) ;
    }
    
    public double[] calc_undistorted_coord (int x, int y, double un_x, double un_y)
    {
    	 double	width = clone.getWidth() / 2.0 ;
         double	height = clone.getHeight() / 2.0 ;
         double	invmaxrad = 1.0 / (width < height ? width : height) ;
         width += _offsetX * width ;
         height += _offsetY * height ;

         double   u = x - width ;
         double   v = y - height ;
         double   r = Math.sqrt(u*u + v*v) ;
         double   theta = Math.atan2(v, u) ;

         double   t = 1 - ((r * _size) * invmaxrad) ;
         t = (t < 0) ? 0 : (t * t * t) ;
         theta += (t * _twist) / 100.0 ;

         un_x = Function.FClampDouble (width + r * Math.cos(theta), 0.0, clone.getWidth()-1.0) ;
         un_y = Function.FClampDouble (height + r * Math.sin(theta), 0.0, clone.getHeight()-1.0) ;
         return new double[]{un_x, un_y};
    }
}