/* $Id: ModeLabelDrag.java 17865 2010-01-12 20:45:26Z 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:

  *    dthompson

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

  *

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

  */

 // Copyright (c) 2008 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.ui;

 import java.util.List;

 import java.awt.Point;

 import java.awt.event.MouseEvent;

 import org.tigris.gef.base.Editor;

 import org.tigris.gef.base.FigModifyingModeImpl;

 import org.tigris.gef.base.PathItemPlacementStrategy;

 import org.tigris.gef.presentation.Fig;

 import org.tigris.gef.presentation.FigEdge;

 /**

  * Mode for dragging (i.e. user repositioning) of Text labels connected to 

  * FigEdges.

  * @author Dave Thompson

  */

 public class ModeLabelDrag extends FigModifyingModeImpl {

     /**

      * The text label that is currently being dragged, or

      * null if nothing is being dragged.

      */

     private Fig dragFig = null;

     /**

      * The FigEdge that contains the label that is currently

      * being dragged.  We have to keep track of this because

      * the FigEdge is the only object that holds references to the

      * PathItems that place it's child figs.  The child Figs do not

      * have these references. 

      * figEdge = null if nothing is being dragged.

      */

     private FigEdge figEdge = null;

     /**

      * Point for tracking a mouse drag, indicates the last recorded mouse 

      * point.  When a new mouse drag event occurs, the difference between

      * the current point and dragBasePoint is the delta in position.

      */

     private Point dragBasePoint = new Point(0, 0);

     /**

      * X-offset for storing the location of the mouse click on a label

      * relative to the centre of the label.  Used while dragging to 

      * ensure that the user can click anywhere to start the drag, and things

      * still behave sensibly.  X component.

      */

     private int deltax = 0;

     /**

      * Y-offset for storing the location of the mouse click on a label

      * relative to the centre of the label.  Used while dragging to 

      * ensure that the user can click anywhere to start the drag, and things

      * still behave sensibly.  X component.

      */

     private int deltay = 0;

     /**

      * Constructor for creating the ModeLabelDrag instance.

      * @param editor The editor which will own this mode.

      */

     public ModeLabelDrag(Editor editor) {

         super(editor);

     }

     /**

      * Constructor for creating the ModeLabelDrag instance.

      */

     public ModeLabelDrag() {

         super();

     }

     /** 

      * Reply a string of instructions that should be shown in the

      * statusbar when this mode starts.

      * @return The text to display in the status bar.

      * @override 

      */

     public String instructions() {

         return "  ";

     }

     /**

      * Grabs label to begin movement. Turns cursor into a hand.

      * @param me The mouse event to process.

      * @override

      * @see org.tigris.gef.base.ModeImpl#mousePressed(java.awt.event.MouseEvent)

      */

     public void mousePressed(MouseEvent me) {

         Point clickPoint = me.getPoint(); 

         Fig underMouse = editor.hit(clickPoint);

         if (underMouse instanceof FigEdge) {

             List<Fig> figList = ((FigEdge)underMouse).getPathItemFigs();

             for (Fig fig : figList) {

                 if (fig.contains(clickPoint)) {

                     // Consume to stop other modes from trying to take over

                     me.consume();

                     dragFig = fig;

                     dragBasePoint = fig.getCenter();

                     deltax = clickPoint.x - dragBasePoint.x;

                     deltay = clickPoint.y - dragBasePoint.y;

                     figEdge = (FigEdge) underMouse;

                     break;

                 }

             }

         }

     }

     /**

      * Handle mouseReleased events.

      * @param me The mouse event to process.

      * @see org.tigris.gef.base.ModeImpl#mouseReleased(java.awt.event.MouseEvent)

      */

     public void mouseReleased(MouseEvent me) {

         if (dragFig != null) {

             dragFig = null;

         }

     }

     /**

      * Handle mouseDragged events.

      * @param me The mouse event to process.

      * @see org.tigris.gef.base.ModeImpl#mouseDragged(java.awt.event.MouseEvent)

      */

     public void mouseDragged(MouseEvent me) {

         if (dragFig != null) {

             me = editor.translateMouseEvent(me);

             Point newPoint = me.getPoint();

             // Subtract the the offset of the click, to take account of user

             // having not initially clicked in the centre.

             newPoint.translate(-deltax, -deltay);

             PathItemPlacementStrategy pips 

                 = figEdge.getPathItemPlacementStrategy(dragFig);

             pips.setPoint(newPoint);

             newPoint = pips.getPoint();

             int dx = newPoint.x - dragBasePoint.x;

             int dy = newPoint.y - dragBasePoint.y;

             dragBasePoint.setLocation(newPoint);

             dragFig.translate(dx, dy);

             me.consume();

             editor.damaged(dragFig);

         }

     }

 }