/* $Id: ClassdiagramInheritanceEdge.java 17863 2010-01-12 20:07:22Z linus $

  *****************************************************************************

  * Copyright (c) 2009 Contributors - see below

  * All rights reserved. This program and the accompanying materials

  * are made available under the terms of the Eclipse Public License v1.0

  * which accompanies this distribution, and is available at

  * http://www.eclipse.org/legal/epl-v10.html

  *

  * Contributors:

  *    linus

  *****************************************************************************

  *

  * Some portions of this file was previously release using the BSD License:

  */

 // Copyright (c) 1996-2007 The Regents of the University of California. All

 // Rights Reserved. Permission to use, copy, modify, and distribute this

 // software and its documentation without fee, and without a written

 // agreement is hereby granted, provided that the above copyright notice

 // and this paragraph appear in all copies.  This software program and

 // documentation are copyrighted by The Regents of the University of

 // California. The software program and documentation are supplied "AS

 // IS", without any accompanying services from The Regents. The Regents

 // does not warrant that the operation of the program will be

 // uninterrupted or error-free. The end-user understands that the program

 // was developed for research purposes and is advised not to rely

 // exclusively on the program for any reason.  IN NO EVENT SHALL THE

 // UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT,

 // SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS,

 // ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF

 // THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF

 // SUCH DAMAGE. THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY

 // WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF

 // MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE

 // PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF

 // CALIFORNIA HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE, SUPPORT,

 // UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

 package org.argouml.uml.diagram.static_structure.layout;

 import org.apache.log4j.Logger;

 import org.tigris.gef.presentation.Fig;

 import org.tigris.gef.presentation.FigEdge;

 /**

  *

  * @author mkl

  */

 public abstract class ClassdiagramInheritanceEdge extends ClassdiagramEdge {

     private static final Logger LOG = Logger

             .getLogger(ClassdiagramInheritanceEdge.class);

     /**

      * The largest difference that we consider equivalent to zero

      */

     private static final int EPSILON = 5;

     /**

      * The figures which are connected by this edge

      */

     private Fig high, low;

     /**

      * Offset used to distribute the lines

      */

     private int offset;

     /**

      * Constructor.

      *

      * @param edge the fig edge

      */

     public ClassdiagramInheritanceEdge(FigEdge edge) {

         super(edge);

         // calculate the higher and lower Figs

         high = getDestFigNode();

         low = getSourceFigNode();

         offset = 0;

     }

     /**

      * @return the vertical offset

      */

     public int getVerticalOffset() {

         return (getVGap() / 2) - 10 + getOffset();

     }

     /**

      * @return the center of the high node

      */

     public int getCenterHigh() {

         return (int) (high.getLocation().getX() + high.getSize().width / 2)

             + getOffset();

     }

     /**

      * @return the center of the low node

      */

     public int getCenterLow() {

         return (int) (low.getLocation().getX() + low.getSize().width / 2)

                 + getOffset();

     }

     /**

      * @return the gap with the node one level down

      */

     public int getDownGap() {

         return (int) (low.getLocation().getY() - getVerticalOffset());

     }

     /**

      * @see org.argouml.uml.diagram.layout.LayoutedEdge#layout()

      *

      * Layout the edges in a way that they form a nice inheritance tree. Try to

      * implement these nice zigzag lines between classes and works well when the

      * row difference is one.

      *

      * @author Markus Klink

      * @since 0.9.6

      */

     public void layout() {

         // now we construct the zig zag inheritance line

         //getUnderlyingFig()

         Fig fig = getUnderlyingFig();

         int centerHigh = getCenterHigh();

         int centerLow = getCenterLow();

         // the amount of the "sidestep"

         int difference = centerHigh - centerLow;

         /*

          * If center points are "close enough" we just adjust the endpoints

          * of the line a little bit.  Otherwise we add a jog in the middle to

          * deal with the offset.

          * 

          * TODO: Epsilon is currently fixed, but could probably be computed

          * dynamically as 10% of the width of the narrowest figure or some

          * other value which is visually not noticeable.

          */

         if (Math.abs(difference) < EPSILON) {

             fig.addPoint(centerLow + (difference / 2 + (difference % 2)), 

                     (int) (low.getLocation().getY()));

             fig.addPoint(centerHigh - (difference / 2),

                     high.getLocation().y + high.getSize().height);

         } else {

             fig.addPoint(centerLow, (int) (low.getLocation().getY()));

             if (LOG.isDebugEnabled()) {

                 LOG.debug("Point: x: " + centerLow + " y: " 

                         + low.getLocation().y);

             }

             getUnderlyingFig().addPoint(centerHigh - difference, getDownGap());

             getUnderlyingFig().addPoint(centerHigh, getDownGap());

             if (LOG.isDebugEnabled()) {

                 LOG.debug("Point: x: " + (centerHigh - difference) + " y: "

                         + getDownGap());

                 LOG.debug("Point: x: " + centerHigh + " y: " + getDownGap());

             }

             fig.addPoint(centerHigh, 

                     high.getLocation().y + high.getSize().height);

             if (LOG.isDebugEnabled()) {

                 LOG.debug("Point x: " + centerHigh + " y: "

                         + (high.getLocation().y + high.getSize().height));

             }

         }

         fig.setFilled(false);

         getCurrentEdge().setFig(getUnderlyingFig());

         // currentEdge.setBetweenNearestPoints(false);

     }

     /**

      * Set the line-offset for this edge

      *

      * @param anOffset

      *            the offset to use for this edge

      */

     public void setOffset(int anOffset) {

         offset = anOffset;

     }

     /**

      * @return Line-offset for this edge

      */

     public int getOffset() {

         return offset;

     }

 }