/**********************************************
    * Copyright (C) 2011 Lukas Laag
    * This file is part of svgreal.
    * 
    * svgreal 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 3 of the License, or
    * (at your option) any later version.
    * 
   * svgreal 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 svgreal.  If not, see http://www.gnu.org/licenses/
   **********************************************/
  package org.vectomatic.svg.edit.client.model.svg;
  
  import org.vectomatic.dom.svg.OMSVGElement;
  import org.vectomatic.dom.svg.OMSVGMatrix;
  import org.vectomatic.dom.svg.OMSVGRect;
  import org.vectomatic.dom.svg.OMSVGSVGElement;
  import org.vectomatic.dom.svg.OMSVGTransform;
  import org.vectomatic.dom.svg.OMSVGTransformList;
  import org.vectomatic.dom.svg.itf.ISVGTransformable;
  
  import com.google.gwt.core.client.GWT;
  
  /**
   * Class to decompose the transform attribute into a matrix
   * product of the form: t.r.s.tinv
   * @author laaglu
   */
  public class Transformation {
  	/**
  	 * The transformable to which this transformation applies
  	 */
  	private ISVGTransformable transformable;
  	/**
  	 * The manipulator scale transform
  	 */
  	public OMSVGTransform getS() {
  		return transformable.getTransform().getBaseVal().getItem(2);
  	}
  	/**
  	 * The manipulator rotate transform
  	 */
  	public OMSVGTransform getR() {
  		return transformable.getTransform().getBaseVal().getItem(1);
  	}
  	/**
  	 * The manipulator translate transform
  	 */
  	public OMSVGTransform getT() {
  		return transformable.getTransform().getBaseVal().getItem(0);
  	}
  	/**
  	 * The manipulator translate inverse transform
  	 */
  	public OMSVGTransform getTinv() {
  		return transformable.getTransform().getBaseVal().getItem(3);
  	}
  	
  	public static Transformation decompose(ISVGTransformable transformable) {
  		OMSVGTransformList transforms = transformable.getTransform().getBaseVal();
  		OMSVGSVGElement svg = ((OMSVGElement)transformable).getOwnerSVGElement();
  		OMSVGRect bbox = transformable.getBBox();
  		OMSVGTransform transform = null;
  		if (transforms.getNumberOfItems() == 0) {
  			transform = transforms.appendItem(svg.createSVGTransform());
  		} else {
  			transform = transforms.consolidate();
  		}
  		OMSVGMatrix m = transform.getMatrix();
  		float sx = (float)Math.sqrt(m.getA() * m.getA() + m.getB() * m.getB());
  		float sy = (float)Math.sqrt(m.getC() * m.getC() + m.getD() * m.getD());
  		float rrad = (float)(Math.acos(m.getA() / sx));
  		if (m.getB() < 0f) {
  			rrad = 2f * (float)Math.PI - rrad;
  		}
  		if (m.getA() * m.getD() < 0f) {
  			sy = -sy;
  		}
  		float cos = (float)Math.cos(rrad);
  		float sin = (float)Math.sin(rrad);
  		float cx = bbox.getCenterX();
  		float cy = bbox.getCenterY();
  		GWT.log("t1x=" + cx + " t1y=" + cy);
  		float tx = m.getE() + sx * cx * cos - sy * cy * sin;
  		float ty = m.getF() + sx * cx * sin + sy * cy * cos;
  
  		Transformation decomposition = new Transformation(transformable);
  		decomposition.getS().setScale(sx, sy);
  		decomposition.getR().setRotate((float)(rrad * 180f / Math.PI), 0, 0);
  		decomposition.getT().setTranslate(tx, ty);
  		decomposition.getTinv().setTranslate(-cx, -cy);
  		
  		return decomposition;		
 	}
 
 	private Transformation(ISVGTransformable transformable) {
 		this.transformable = transformable;
 		OMSVGTransformList xforms = transformable.getTransform().getBaseVal();
 		xforms.clear();
 		OMSVGSVGElement svg = ((OMSVGElement)transformable).getOwnerSVGElement();
 		for (int i = 0; i < 4; i++) {
 			xforms.appendItem(svg.createSVGTransform());
 		}
 	}
 	@Override
 	public String toString() {
 		StringBuilder builder = new StringBuilder();
 		builder.append("t=");
 		builder.append(getT().getDescription());
 		builder.append(";r=");
 		builder.append(getR().getDescription());
 		builder.append(";s=");
 		builder.append(getS().getDescription());
 		builder.append(";tinv=");
 		builder.append(getTinv().getDescription());
 		return builder.toString();
 	}
 }