// PathVisio,
// a tool for data visualization and analysis using Biological Pathways
// Copyright 2006-2011 BiGCaT Bioinformatics
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package org.pathvisio.core.view;

import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.AffineTransform;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.ConcurrentModificationException;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import javax.swing.Action;
import javax.swing.KeyStroke;
import javax.swing.Timer;

import org.pathvisio.core.Engine;
import org.pathvisio.core.debug.Logger;
import org.pathvisio.core.model.GraphLink.GraphIdContainer;
import org.pathvisio.core.model.GroupStyle;
import org.pathvisio.core.model.MLine;
import org.pathvisio.core.model.ObjectType;
import org.pathvisio.core.model.Pathway;
import org.pathvisio.core.model.Pathway.StatusFlagEvent;
import org.pathvisio.core.model.PathwayElement;
import org.pathvisio.core.model.PathwayElement.MAnchor;
import org.pathvisio.core.model.PathwayElement.MPoint;
import org.pathvisio.core.model.PathwayEvent;
import org.pathvisio.core.model.PathwayListener;
import org.pathvisio.core.preferences.GlobalPreference;
import org.pathvisio.core.preferences.PreferenceManager;
import org.pathvisio.core.util.Utils;
import org.pathvisio.core.view.SelectionBox.SelectionListener;
import org.pathvisio.core.view.VPathwayEvent.VPathwayEventType;
import org.pathvisio.core.view.ViewActions.KeyMoveAction;
import org.pathvisio.core.view.ViewActions.TextFormattingAction;

/**
 * This class implements and handles a drawing. Graphics objects are stored in
 * the drawing and can be visualized. The class also provides methods for mouse
 * and key event handling.
 *
 * It's necessary to call PreferenceManager.init() before you can instantiate
 * this class.
 */
public class VPathway implements PathwayListener
{
	private static final double FUZZY_SIZE = 8; // fuzz-factor around mouse cursor
	static final int ZORDER_SELECTIONBOX = Integer.MAX_VALUE;
	static final int ZORDER_HANDLE = Integer.MAX_VALUE - 1;
	
	// flags for cursor change if mouse is over a
	// label with href and ctrl button is pressed
	private boolean stateCtrl = false;
	private boolean stateEntered = false;
	private VPathwayElement lastEnteredElement = null;
	
	private boolean selectionEnabled = true;

	private Pathway temporaryCopy = null;

	/**
	 * Retuns true if snap to anchors is enabled
	 */
	public boolean isSnapToAnchors()
	{
		return PreferenceManager.getCurrent().getBoolean(GlobalPreference.SNAP_TO_ANCHOR);
	}

	/**
	 * Returns true if the selection capability of this VPathway is enabled
	 */
	public boolean getSelectionEnabled()
	{
		return selectionEnabled;
	}

	/**
	 * You can disable the selection capability of this VPathway by passing
	 * false. This is not used within Pathvisio, but it is meant for embedding
	 * VPathway in other applications, where selections may not be needed.
	 */
	public void setSelectionEnabled(boolean value)
	{
		selectionEnabled = value;
	}

	private VPathwayWrapper parent; // may be null

	/**
	 * All objects that are visible on this mapp, including the handles but
	 * excluding the legend, mappInfo and selectionBox objects
	 */
	private List<VPathwayElement> drawingObjects;
	private List<VPathwayElement> toAdd = new ArrayList<VPathwayElement>();

	/**
	 * Obtain all VPathwayElements on this VPathway
	 */
	public List<VPathwayElement> getDrawingObjects()
	{
		return drawingObjects;
	}

	/**
	 * The {@link VPathwayElement} that is pressed last mouseDown event}
	 */
	private VPathwayElement pressedObject = null;

	/**
	 * {@link InfoBox} object that contains information about this pathway,
	 * currently only used for information in PropertyPanel
	 * (TODO: has to be implemented to behave the same as any Graphics object
	 * when displayed on the drawing)
	 */
	private InfoBox infoBox;

	private Pathway data;

	/**
	 * Returns the associated org.pathvisio.model.Pathway object
	 */
	public Pathway getPathwayModel()
	{
		return data;
	}

	SelectionBox selection;

	private boolean editMode = true;

	/**
	 * Checks if this drawing is in edit mode
	 *
	 * @return false if in edit mode, true if not
	 */
	public boolean isEditMode()
	{
		return editMode;
	}

	/**
	 * Constructor for this class.
	 *
	 * @param parent
	 *            Optional gui-specific wrapper for this VPathway
	 */
	public VPathway(VPathwayWrapper parent)
	{
		//NOTE: you need to call PreferenceManager.init() at application start,
		// before instantiating a VPathway
		//This used to be called by Engine.init(), but not anymore.
		//TODO: make preferencemanager a non-static object, so this check is obsolete.
		if (PreferenceManager.getCurrent() == null)
		{
			throw new InstantiationError(
					"Please call PreferenceManager.init() before instantiating a VPathway"
			);
		}
		this.parent = parent;

		drawingObjects = new ArrayList<VPathwayElement>();

		selection = new SelectionBox(this);

		//Code that uses VPathway have to initialize
		//the keyboard actions explicitly, if necessary.
		//registerKeyboardActions();
	}

	/**
	 * This will cause a complete redraw of the 
	 * pathway to be scheduled. 
	 * The redraw will happen as soon as all other swing 
	 * events are processed.
	 * <p>
	 * Use this only after large changes (e.g. loading a new pathway, 
	 * applying a new visualization method) as it is quite slow.
	 */
	public void redraw()
	{
		if (parent != null)
			parent.redraw();
	}

	public VPathwayWrapper getWrapper()
	{
		return parent;
	}

	/**
	 * Map the contents of a single data object to this VPathway.
	 */
	private Graphics fromModelElement(PathwayElement o)
	{
		Graphics result = null;
		switch (o.getObjectType())
		{
		case DATANODE:
			result = new GeneProduct(this, o);
			break;
		case SHAPE:
			result = new Shape(this, o);
			break;
		case LINE:
			result = new Line(this, o);
			break;
		case MAPPINFO:
			InfoBox mi = new InfoBox(this, o);
			result = mi;
			mi.markDirty();
			break;
		case LABEL:
			result = new Label(this, o);
			break;
		case GROUP:
			result = new Group(this, o);
			break;
		case STATE:
			result = new State (this, o);
			break;
		case LEGEND:
			result = new Legend(this, o);
			break;
		}
		return result;
	}

	/**
	 * used by undo manager.
	 */
	public void replacePathway(Pathway originalState)
	{
		boolean changed = data.hasChanged();

		clearSelection();
		drawingObjects = new ArrayList<VPathwayElement>();
		// transfer selectionBox with corresponding listeners
		SelectionBox newSelection = new SelectionBox(this);
		for(Iterator<SelectionListener> i = selection.getListeners().iterator(); i.hasNext(); )
		{
			SelectionListener l = i.next();
			newSelection.addListener(l);
			i.remove();
		}
		selection = newSelection;
		data.removeListener(this);
		pressedObject = null;
		data.transferStatusFlagListeners(originalState);
		data = null;
		pointsMtoV = new HashMap<MPoint, VPoint>();
		fromModel(originalState);

		if(changed != originalState.hasChanged()) {
			data.fireStatusFlagEvent(new StatusFlagEvent(originalState.hasChanged()));
		}
	}

	/**
	 * Maps the contents of a pathway to this VPathway
	 */
	public void fromModel(Pathway aData)
	{
		Logger.log.trace("Create view structure");

		data = aData;
		for (PathwayElement o : data.getDataObjects())
		{
			fromModelElement(o);
		}

		// data.fireObjectModifiedEvent(new PathwayEvent(null,
		// PathwayEvent.MODIFIED_GENERAL));
		fireVPathwayEvent(new VPathwayEvent(this, VPathwayEventType.MODEL_LOADED));
		data.addListener(this);
		undoManager.setPathway(data);
		addScheduled();
		Logger.log.trace("Done creating view structure");
	}

	Template newTemplate = null;

	/**
	 * Method to set the template that provides the new graphics type that has
	 * to be added next time the user clicks on the drawing.
	 *
	 * @param t A template that provides the elements to be added
	 */
	public void setNewTemplate(Template t) {
		newTemplate = t;
	}

	/**
	 * Adds object boundaries to the "dirty" area, the area which needs to be redrawn. 
	 * The redraw will not happen immediately, but
	 * will be scheduled on the event dispatch thread.
	 */
	void addDirtyRect(Rectangle2D ar)
	{
		if (parent != null) parent.redraw(ar.getBounds());
	}

	/**
	 * Deprecated: Does nothing, redraws are now scheduled by Swing.
	 * call addDirtyRect() or redraw() instead, or remove calls to this altogether
	 */
	@Deprecated 
	public void redrawDirtyRect()
	{
	}

	/**
	 * Sets the MappInfo containing information on the pathway
	 *
	 * @param mappInfo
	 */
	public void setMappInfo(InfoBox mappInfo)
	{
		this.infoBox = mappInfo;
	}

	/**
	 * Gets the MappInfo containing information on the pathway
	 */
	public InfoBox getMappInfo()
	{
		return infoBox;
	}

	/**
	 * Adds an element to the drawing
	 *
	 * @param o
	 *            the element to add
	 */
	public void addObject(VPathwayElement o)
	{
		toAdd.add (o);
	}

	/**
	 * Gets the view representation {@link Graphics} of the given model element
	 * {@link PathwayElement}
	 *
	 * @param e
	 * @return the {@link Graphics} representing the given
	 *         {@link PathwayElement} or <code>null</code> if no view is
	 *         available
	 */
	public Graphics getPathwayElementView(PathwayElement e)
	{
		// TODO: store Graphics in a hashmap to improve speed
		for (VPathwayElement ve : drawingObjects)
		{
			if (ve instanceof Graphics)
			{
				Graphics ge = (Graphics) ve;
				if (ge.getPathwayElement() == e)
					return ge;
			}
		}
		return null;
	}

	Map<MPoint, VPoint> pointsMtoV = new HashMap<MPoint, VPoint>();

	protected VPoint getPoint(MPoint mPoint)
	{
		return pointsMtoV.get(mPoint);
	}

	public VPoint newPoint(MPoint mPoint, Line line)
	{
		VPoint p = pointsMtoV.get(mPoint);
		if (p == null) {
			p = new VPoint(this, mPoint, line);
			pointsMtoV.put(mPoint, p);
		}
		return p;
	}

	/**
	 * Set this drawing to editmode
	 *
	 * @param editMode
	 *            true if editmode has to be enabled, false if disabled (view
	 *            mode)
	 */
	public void setEditMode(boolean editMode)
	{
		this.editMode = editMode;
		if (!editMode)
		{
			clearSelection();
		}

		redraw();
		VPathwayEventType type = editMode ? VPathwayEventType.EDIT_MODE_ON
				: VPathwayEventType.EDIT_MODE_OFF;
		fireVPathwayEvent(new VPathwayEvent(this, type));
	}

	private double zoomFactor = 1.0;

	/**
	 * Get the current zoomfactor used. 1 means 100%, 1 gpml unit = 1 pixel
	 * 2 means 200%, 0.5 gpml unit = 1 pixel
	 *
	 * To distinguish between model coordinates and view coordinates, we prefix
	 * all coordinates with either v or m (or V or M). For example:
	 *
	 * mTop = gdata.getMTop(); vTop = GeneProduct.getVTop();
	 *
	 * Calculations done on M's and V's should always match. The only way to
	 * convert is to use the functions mFromV and vFromM.
	 *
	 * Correct: mRight = mLeft + mWidth; Wrong: mLeft += vDx; Fixed: mLeft +=
	 * mFromV(vDx);
	 *
	 * @return the current zoomfactor
	 */
	public double getZoomFactor()
	{
		return zoomFactor;
	}

	/**
	 * same as getZoomFactor, but in %
	 *
	 * @return
	 */
	public double getPctZoom()
	{
		return zoomFactor * 100;
	}

	/**
	 * Sets the drawings zoom in percent
	 *
	 * @param pctZoomFactor
	 *            zoomfactor in percent
	 * @see #getFitZoomFactor() for fitting the pathway inside the viewport.
	 */
	public void setPctZoom(double pctZoomFactor)
	{
		zoomFactor = pctZoomFactor / 100.0;		
		for(VPathwayElement vpe : drawingObjects) {
			vpe.zoomChanged();
		}
		if (parent != null) parent.resized();
	}

	public void centeredZoom(double pctZoomFactor)
	{
		if (parent != null)
		{
			Rectangle vr = parent.getViewRect();

			double mx = mFromV(vr.getCenterX());
			double my = mFromV(vr.getCenterY());
			Logger.log.info ("center: " + mx + ", " + my);
			setPctZoom(pctZoomFactor);
			parent.scrollCenterTo(
					(int)vFromM(mx), (int)vFromM(my));
		}
		else
			setPctZoom(pctZoomFactor);
	}

	public void zoomToCursor(double pctZoomFactor, Point cursor)
	{
		if (parent == null) return;
		
		// offset between mouse and center of the viewport
		double vDeltax = cursor.getX() - parent.getViewRect().getCenterX();
		double vDeltay = cursor.getY() - parent.getViewRect().getCenterY();;
		
		// model coordinates where the mouse is pointing at
		double mx = mFromV(cursor.getX());
		double my = mFromV(cursor.getY());
		
		// adjust zoom
		setPctZoom(pctZoomFactor);
		
		// put mx, my back under the mouse
		parent.scrollCenterTo((int)(vFromM(mx) - vDeltax), 
				(int)(vFromM(my) - vDeltay));
	}
	
	/**
	 * Calculate the zoom factor that would
	 * make the pathway fit in the viewport.
	 */
	public double getFitZoomFactor()
	{
		double result;
		Dimension drawingSize = new Dimension (getVWidth(), getVHeight());
		Dimension viewportSize = getWrapper().getViewRect().getSize();
		result = (int) Math.min(getPctZoom()
				* (double) viewportSize.width / drawingSize.width,
				getPctZoom() * (double) viewportSize.height
						/ drawingSize.height);
		return result;
	}

	public void setPressedObject(VPathwayElement o)
	{
		pressedObject = o;
	}


	private LinkAnchor currentLinkAnchor;

	/**
	 * @arg p2d point where mouse is at
	 */
	private void linkPointToObject(Point2D p2d, Handle g)
	{
		if (dragUndoState == DRAG_UNDO_CHANGE_START)
		{
			dragUndoState = DRAG_UNDO_CHANGED;
		}
		hideLinkAnchors();
        VPoint p = (VPoint) g.getAdjustable();
        Line l = p.getLine();
        PathwayElement pe = l.getPathwayElement();
		List<LinkProvider> objects = getLinkProvidersAt(p2d);
		//Fix for preventing grouped line to link to its own group
		//Remove the group from the list of linkproviders
		//Also remove the line anchors to prevent linking a line
		//to it's own anchors
		if(g.getAdjustable() instanceof VPoint) {
            if(pe.getGroupRef() != null) {
				PathwayElement group = getPathwayModel().getGroupById(pe.getGroupRef());
				objects.remove(getPathwayElementView(group));
			}
			for(VAnchor va : l.getVAnchors()) {
				objects.remove(va);
			}
		}

		GraphIdContainer idc = null;
		for (LinkProvider lp : objects)
		{
			if (lp instanceof VAnchor && ((VAnchor)lp).getMAnchor().getShape().isDisallowLinks()) {
             	   break;
            	}
			lp.showLinkAnchors();
			LinkAnchor la = lp.getLinkAnchorAt(p2d);
			if(la != null) {
				//Set graphRef
				la.link(p.getMPoint());
				idc = la.getGraphIdContainer();
				if(currentLinkAnchor != null) {
					currentLinkAnchor.unhighlight();
				}
				la.highlight();
				currentLinkAnchor = la;
				break;
			}
		}

		if(idc == null && p.getMPoint().isLinked()) {
            String graphRef = p.getMPoint().getGraphRef();
            p.getMPoint().unlink();
            if(currentLinkAnchor != null) {
                if (pe instanceof MLine && isAnotherLineLinked(graphRef, (MLine)pe)) {

                } else if (currentLinkAnchor.getGraphIdContainer() instanceof MAnchor &&
                    currentLinkAnchor.getGraphIdContainer().getGraphId().equals(graphRef)) {
                    currentLinkAnchor.getGraphIdContainer().setGraphId(null);
                }
                currentLinkAnchor.unhighlight();
			}
        }
	}

    private boolean isAnotherLineLinked(String graphRef, MLine currLine) {
        for (PathwayElement element : getPathwayModel().getDataObjects()) {
             if (element instanceof MLine) {
                 if (element.equals(currLine)) {
                     continue;
                 }
                 for (MPoint point:element.getMPoints()) {
                      if (point.getGraphRef() == null) {
                          // skip point
                      } else if (graphRef != null && point.getGraphRef().equals(graphRef)) {
                          return true;
                      }
                 }
             }
        }
        return false;
    }

    private void hideLinkAnchors() {
		for(VPathwayElement pe : getDrawingObjects()) {
			if(pe instanceof LinkProvider) {
				((LinkProvider)pe).hideLinkAnchors();
			}
		}
	}

	private boolean snapModifierPressed;

	/**
	 * Check whether the key is pressed to restrict handle movement. 
	 * When the key is down:
	 * <li> lines snap to certain angles (but only when preference is on).
	 * <li> rotation handles on shapes snap to certain angles
	 * <li> shape snaps to a fixed aspect ratio
	 * <p>
	 * @see GlobalPreference#SNAP_TO_ANGLE for the global setting
	 * @see GlobalPreference#SNAP_TO_ANGLE_STEP for the angle step to be used
	 * @return
	 */
	public boolean isSnapModifierPressed() {
		return snapModifierPressed;
	}

	private int vPreviousX;
	private int vPreviousY;
	private boolean isDragging;

	/**
	 * handles mouse movement
	 */
	public void mouseMove(MouseEvent ve)
	{
		snapModifierPressed = ve.isKeyDown(MouseEvent.M_SHIFT);
		// If draggin, drag the pressed object
		// And only when the right button isn't clicked
		if (pressedObject != null && isDragging && !ve.isKeyDown(java.awt.event.MouseEvent.BUTTON3_DOWN_MASK))
		{
			if (dragUndoState == DRAG_UNDO_CHANGE_START)
			{
				dragUndoState = DRAG_UNDO_CHANGED;
			}
			double vdx = ve.getX() - vPreviousX;
			double vdy = ve.getY() - vPreviousY;
			if (pressedObject instanceof Handle)
			{
				((Handle) (pressedObject)).vMoveTo(ve.getX(), ve.getY());
			} else
			{
				pressedObject.vMoveBy(vdx, vdy);
			}

			vPreviousX = ve.getX();
			vPreviousY = ve.getY();

			if (pressedObject instanceof Handle
					&& newTemplate == null
					&& ((Handle) pressedObject).getAdjustable() instanceof VPoint)
			{
				linkPointToObject(new Point2D.Double(ve.getX(), ve.getY()),
						(Handle) pressedObject);
			}
		} else {
			List<VPathwayElement> objects = getObjectsAt(new Point2D.Double(ve.getX(), ve.getY()));
			
			//Process mouseexit events
			processMouseExitEvents(ve, objects);
			
			//Process mouseenter events
			processMouseEnterEvents(ve, objects);
		}

		hoverManager.reset(ve);
	}

	private void processMouseEnterEvents(MouseEvent ve, List<VPathwayElement> objects) {
		for(VPathwayElement vpe : objects) {
			if(!lastMouseOver.contains(vpe)) {
				lastMouseOver.add(vpe);
				stateEntered = true;
				if(vpe instanceof Label && !((Label)vpe).gdata.getHref().equals("")) {
					lastEnteredElement = vpe;
				} else {					
					fireVElementMouseEvent(new VElementMouseEvent(
							this, VElementMouseEvent.TYPE_MOUSEENTER, vpe, ve
					));
				}
			}
		}
		if(lastEnteredElement != null) {
			fireHyperlinkUpdate(lastEnteredElement);
		}
	}

	private void processMouseExitEvents(MouseEvent ve, List<VPathwayElement> objects) {
		Set<VPathwayElement> toRemove = new HashSet<VPathwayElement>();
		
		for(VPathwayElement vpe : lastMouseOver) {
			if(!objects.contains(vpe)) {
				toRemove.add(vpe);
				stateEntered = false;
				if(lastEnteredElement == vpe) {
					fireHyperlinkUpdate(lastEnteredElement);
					lastEnteredElement = null;
				} else {
					fireVElementMouseEvent(new VElementMouseEvent(
							this, VElementMouseEvent.TYPE_MOUSEEXIT, vpe, ve
					));
				}
				
			}
		}
		
		lastMouseOver.removeAll(toRemove);
	}
	
	private Set<VPathwayElement> lastMouseOver = new HashSet<VPathwayElement>();
	private HoverManager hoverManager = new HoverManager();

	private class HoverManager implements ActionListener {
		static final int DELAY = 1000; //tooltip delay in ms
		boolean tooltipDisplayed = false;

		MouseEvent lastEvent = null;

		Timer timer;

		public HoverManager() {
			timer = new Timer(DELAY, this);
		}

		public void actionPerformed(ActionEvent e) {
			if(!tooltipDisplayed) {
				 fireVPathwayEvent(
						new VPathwayEvent(
							VPathway.this,
							getObjectsAt(lastEvent.getLocation()), lastEvent,
							VPathwayEventType.ELEMENT_HOVER)
				);
				 tooltipDisplayed = true;
			}
		}

		void reset(MouseEvent e) {
			lastEvent = e;
			tooltipDisplayed = false;
			timer.restart();
		}

		void stop() {
			timer.stop();
		}
	}

	/**
	 * Handles movement of objects with the arrow keys
	 *
	 * @param ks
	 */
	public void moveByKey(KeyStroke ks, int increment)
	{
		List<Graphics> selectedGraphics = getSelectedNonGroupGraphics();

		if (selectedGraphics.size() > 0)
		{

			switch (ks.getKeyCode())
			{
			case 37:
				undoManager.newAction("Move object");
				selection.vMoveBy(-increment, 0);
				break;
			case 39:
				undoManager.newAction("Move object");
				selection.vMoveBy(increment, 0);
				break;
			case 38:
				undoManager.newAction("Move object");
				selection.vMoveBy(0, -increment);
				break;
			case 40:
				undoManager.newAction("Move object");
				selection.vMoveBy(0, increment);
			}
		}
	}

	public void selectObject(VPathwayElement o)
	{
		clearSelection();
		selection.addToSelection(o);
	}
	
	 // opens href of a Label with ctrl + click
	private boolean openHref(MouseEvent e, VPathwayElement o) {
		if(e.isKeyDown(128) && o != null && o instanceof Label) {
			String href = ((Label)o).gdata.getHref();
			if(selection.getSelection().size() < 1 && !href.equals("")) {
				fireVPathwayEvent(new VPathwayEvent(this, o, VPathwayEventType.HREF_ACTIVATED));
				return true;
			}
		}
		return false;
	}

	/**
	 * Handles mouse Pressed input
	 */
	public void mouseDown(MouseEvent e)
	{
		VPathwayElement vpe = getObjectAt(e.getLocation());
		if(!openHref(e, vpe)) {
			// setFocus();
			vDragStart = new Point(e.getX(), e.getY());
			temporaryCopy = (Pathway) data.clone();
		
			if (editMode)
			{
				if (newTemplate != null)
				{
					newObject(e.getLocation());
					// SwtGui.getCurrent().getWindow().deselectNewItemActions();
				} else
				{
					pressedObject = vpe;
					editObject(e);
				}
			} else
			{
				mouseDownViewMode(e);
			}
			if (pressedObject != null)
			{
				fireVPathwayEvent(new VPathwayEvent(this, pressedObject, e,
						VPathwayEventType.ELEMENT_CLICKED_DOWN));
			}
		}
	}

	/**
	 * Handles mouse Released input
	 */
	public void mouseUp(MouseEvent e)
	{
		if (isDragging)
		{
			if (dragUndoState == DRAG_UNDO_CHANGED)
			{
				assert (temporaryCopy != null);
				// further specify the type of undo event,
				// depending on the type of object being dragged
				String message = "Drag Object";
				if (pressedObject instanceof Handle)
				{
					if (((Handle) pressedObject).getFreedom() == Handle.Freedom.ROTATION)
					{
						message = "Rotate Object";
					} else
					{
						message = "Resize Object";
					}
				}
				undoManager.newAction(new UndoAction(message, temporaryCopy));
				temporaryCopy = null;
			}
			resetHighlight();
			hideLinkAnchors();
			if (selection.isSelecting())
			{ // If we were selecting, stop it
				selection.stopSelecting();
			}
			// check if we placed a new object by clicking or dragging
			// if it was a click, give object the initial size.
			else if (newObject != null
					&& Math.abs(vDragStart.x - e.getX()) <= MIN_DRAG_LENGTH
					&& Math.abs(vDragStart.y - e.getY()) <= MIN_DRAG_LENGTH)
			{
				newObject.setInitialSize();
			}
			newObject = null;
			setNewTemplate(null);
		}
		isDragging = false;
		dragUndoState = DRAG_UNDO_NOT_RECORDING;
		if (pressedObject != null)
		{
			fireVPathwayEvent(new VPathwayEvent(this, pressedObject, e,
					VPathwayEventType.ELEMENT_CLICKED_UP));
		}
	}

	/**
	 * Handles mouse entered input
	 */
	public void mouseDoubleClick(MouseEvent e)
	{
		VPathwayElement o = getObjectAt(e.getLocation());
		if (o != null)
		{
			Logger.log.trace("Fire double click event to " + listeners.size());
			for(VPathwayListener l : listeners) {
				Logger.log.trace("\t " + l.hashCode() + ", " + l);
			}
			fireVPathwayEvent(new VPathwayEvent(this, o,
					VPathwayEventType.ELEMENT_DOUBLE_CLICKED));
		}
	}

	/**
	 * Paints all components in the drawing. This method is called automatically
	 * in the painting process. This method will draw opaquely, meaning it will erase the background. 
	 * @param g2d the graphics device to draw on. The method will not draw outside the clipping area. 
	 */
	public void draw(Graphics2D g2d)
	{
		addScheduled();
		cleanUp();

		try
		{
			//save original, non-clipped, to pass on to VPathwayEvent
			Graphics2D g2dFull = (Graphics2D)g2d.create();

			// we only redraw the part within the clipping area.
			Rectangle area = g2d.getClipBounds();
			if (area == null)
			{
				Dimension size = parent == null ? 
						new Dimension(getVWidth(), getVHeight()) : 
							parent.getViewRect().getSize(); //Draw the visible area
				area = new Rectangle(0, 0, size.width, size.height);
			}

			// erase the background
			g2d.setColor(java.awt.Color.WHITE);
			g2d.fillRect(area.x, area.y, area.width, area.height);

			g2d.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING,
					RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
			g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
					RenderingHints.VALUE_ANTIALIAS_ON);

			g2d.clip(area);
			g2d.setColor(java.awt.Color.BLACK);
			Collections.sort(drawingObjects);
			cleanUp();
			for (VPathwayElement o : drawingObjects)
			{
				if (o.vIntersects(area))
				{
					if (checkDrawAllowed(o))
					{
						o.draw((Graphics2D) g2d.create());
						fireVPathwayEvent(new VPathwayEvent(this, o,
								(Graphics2D) g2dFull.create(),
								VPathwayEventType.ELEMENT_DRAWN));
					}
				}
			}
		}
		catch (ConcurrentModificationException ex)
		{
			// guard against messing up repaint event completely
			Logger.log.error ("Concurrent modification", ex);
		}
	}

	boolean checkDrawAllowed(VPathwayElement o)
	{
		if (isEditMode())
			return true;
		else
			return !(o instanceof Handle || (o == selection && !isDragging));
	}

	/**
	 * deselect all elements on the drawing and resets the selectionbox.
	 */
	public void clearSelection()
	{
		clearSelection(0, 0);
	}

	/**
	 * deselect all elements on the drawing and resets the selectionbox to the
	 * given coordinates Equivalent to
	 * {@link SelectionBox#reset(double, double))}
	 */
	private void clearSelection(double x, double y)
	{
		for (VPathwayElement e : drawingObjects)
			e.deselect();
		selection.reset(x, y);
	}


	static final int MULTI_SELECT_MASK = MouseEvent.M_SHIFT |
		(Utils.getOS() == Utils.OS_MAC ? MouseEvent.M_META : MouseEvent.M_CTRL);

	/**
	 * Handles event when on mouseDown in case the drawing is in view mode (does
	 * nothing yet)
	 *
	 * @param e
	 *            the mouse event to handle
	 */
	private void mouseDownViewMode(MouseEvent e)
	{
		Point2D p2d = new Point2D.Double(e.getX(), e.getY());

		pressedObject = getObjectAt(p2d);

		if (pressedObject != null)
		{
			// Shift or Ctrl or Meta pressed, add/remove from selection
			boolean modifierPressed = e.isKeyDown(MULTI_SELECT_MASK);
			doClickSelect(p2d, modifierPressed);
		}
		else
			startSelecting(p2d);
	}

	/**
	 * Initializes selection, resetting the selectionbox and then setting it to
	 * the position specified
	 *
	 * @param vp -
	 *            the point to start with the selection
	 */
	void startSelecting(Point2D vp)
	{
		if (!selectionEnabled)
			return;

		vPreviousX = (int) vp.getX();
		vPreviousY = (int) vp.getY();
		isDragging = true;
		dragUndoState = DRAG_UNDO_NOT_RECORDING;

		clearSelection(vp.getX(), vp.getY());
		selection.startSelecting();
		pressedObject = selection.getCornerHandle();
	}

	/**
	 * Resets highlighting, unhighlights all GmmlDrawingObjects
	 */
	public void resetHighlight()
	{
		for (VPathwayElement o : drawingObjects)
			o.unhighlight();
		redrawDirtyRect();
	}

	/**
	 * Called by MouseDown, when we're in editting mode and we're not adding new
	 * objects prepares for dragging the object
	 * @param pressedObject 
	 */
	private void editObject(MouseEvent e)
	{
		// if we clicked on an object
		if (pressedObject != null)
		{
			// Shift pressed, add/remove from selection
			boolean modifierPressed = e.isKeyDown(MULTI_SELECT_MASK);
			// if our object is an handle, select also it's parent.
			if (pressedObject instanceof Handle)
			{
				VPathwayElement parent = ((Handle) pressedObject).getParent();
				parent.select();
				//Special treatment for anchor
				if(parent instanceof VAnchor)
				{
					doClickSelect(e.getLocation(), modifierPressed);
				}
			}
			else
			{
				doClickSelect(e.getLocation(), modifierPressed);
			}

			// start dragging
			vPreviousX = e.getX();
			vPreviousY = e.getY();

			isDragging = true;
			dragUndoState = DRAG_UNDO_CHANGE_START;
		} else
		{
			// start dragging selectionbox
			startSelecting(e.getLocation());
		}
	}
	
	/**
	 * Find the object at a particular location on the drawing
	 *
	 * if you want to get more than one,
	 *
	 * @see #getObjectsAt(Point2D)
	 */
	public VPathwayElement getObjectAt(Point2D p2d)
	{
		int zmax = Integer.MIN_VALUE; 
		VPathwayElement probj = null;
		for (VPathwayElement o : drawingObjects)
		{
			// first we use vContains, which is good for detecting (non-transparent) shapes
			if (o.vContains(p2d) && o.getZOrder() > zmax)
			{
				probj = o;
				zmax = o.getZOrder();
			}
		}
		if (probj == null)
		{
			// if there is nothing at that point, we use vIntersects with a fuzz area,
			// which is good for detecting lines and transparent shapes.
			Rectangle2D fuzz = new Rectangle2D.Double (
					p2d.getX() - FUZZY_SIZE, p2d.getY() - FUZZY_SIZE, FUZZY_SIZE * 2, FUZZY_SIZE * 2);
			for (VPathwayElement o : drawingObjects)
			{
				if (o.vIntersects(fuzz) && o.getZOrder() > zmax)
				{
					probj = o;
					zmax = o.getZOrder();
				}
			}
		}
		return probj;
	}

	/**
	 * Find all objects at a particular location on the drawing
	 *
	 * if you only need the top object,
	 *
	 * @see #getObjectAt(Point2D)
	 */
	public List<VPathwayElement> getObjectsAt(Point2D p2d)
	{
		List<VPathwayElement> result = new ArrayList<VPathwayElement>();
		for (VPathwayElement o : drawingObjects)
		{
			if (o.vContains(p2d))
			{
				result.add(o);
			}
		}
		return result;
	}

	private List<LinkProvider> getLinkProvidersAt(Point2D p) {
		List<LinkProvider> result = new ArrayList<LinkProvider>();
		for (VPathwayElement o : drawingObjects)
		{
			if (o instanceof LinkProvider && o.getVBounds().contains(p))
			{
				result.add((LinkProvider)o);
			}
		}
		return result;
	}

	/**
	 * if modifierPressed is true, the selected object will be added to
	 * the selection, rather than creating a new selection with just one object.
	 * if modifierPressed is true when selecting a Group object, then a
	 * new selection is made of the children, allowing selection into groups.
	 *
	 * modifierPressed should be true when either SHIFT or CTRL/COMMAND is pressed.
	 */
	void doClickSelect(Point2D p2d, boolean modifierPressed)
	{
		if (!selectionEnabled)
			return;

		if (modifierPressed)
		{
			if (pressedObject instanceof SelectionBox)
			{ // Object inside selectionbox clicked:
				// pass to selectionbox
				selection.objectClicked(p2d);
			} else if (pressedObject.isSelected())
			{ // Already in selection:
				// remove
				selection.removeFromSelection(pressedObject);
			} else
			{ // Not in selection:
				// add
				selection.addToSelection(pressedObject);
			}
			pressedObject = selection; // Set dragging to selectionbox
		} else
		// Shift or Ctrl not pressed
		{
			// If pressedobject is not selectionbox:
			// Clear current selection and select pressed object
			if (!(pressedObject instanceof SelectionBox))
			{
				clearSelection();
				//If the object is a handle, select the parent instead
				if(pressedObject instanceof Handle) {
					VPathwayElement parent = ((Handle)pressedObject).getParent();
					selection.addToSelection((VPathwayElement)parent);
				} else {
					selection.addToSelection(pressedObject);
				}
			} else
			{ // Check if clicked object inside selectionbox
				if (selection.getChild(p2d) == null)
					clearSelection();
			}
		}
		redrawDirtyRect();
	}

	/**
	 * pathvisio distinguishes between placing objects with a click or with a
	 * drag. If you don't move the cursor in between the mousedown and mouseup
	 * event, the object is placed with a default initial size.
	 *
	 * vDragStart is used to determine the mousemovement during the click.
	 */
	private Point vDragStart;

	/**
	 * dragUndoState determines what should be done when you release the mouse
	 * button after dragging an object.
	 *
	 * if it is DRAG_UNDO_NOT_RECORDING, it's not necessary to record an event.
	 * This is the case when we were dragging a selection rectangle, or a new
	 * object (in which case the change event was already recorded)
	 *
	 * in other cases, it is set to DRAG_UNDO_CHANGE_START at the start of the
	 * drag. If additional move events occur, the state is changed to
	 * DRAG_UNDO_CHANGED. The latter will lead to recording of the undo event.
	 */
	private static final int DRAG_UNDO_NOT_RECORDING = 0;
	private static final int DRAG_UNDO_CHANGE_START = 1;
	private static final int DRAG_UNDO_CHANGED = 2;

	private int dragUndoState = DRAG_UNDO_NOT_RECORDING;

	/** newly placed object, is set to null again when mouse button is released */
	private PathwayElement newObject = null;

	/** minimum drag length for it to be considered a drag and not a click */
	private static final int MIN_DRAG_LENGTH = 3;

	/**
	 * Add a new object to the drawing {@see VPathway#setNewGraphics(int)}
	 *
	 * @param ve
	 *            The point where the user clicked on the drawing to add a new
	 *            graphics
	 */
	private void newObject(Point ve)
	{
		undoManager.newAction("New Object");
		double mx = mFromV((double) ve.x);
		double my = mFromV((double) ve.y);

		PathwayElement[] newObjects = newTemplate.addElements(data, mx, my);

		addScheduled();
		if (newObjects != null && newObjects.length > 0) {
			isDragging = true;
			dragUndoState = DRAG_UNDO_NOT_RECORDING;

			if(newObjects.length > 1) {
				clearSelection();
				//Multiple objects: select all and use selectionbox as dragging object
				for(PathwayElement pwe : newObjects) {
					Graphics g = getPathwayElementView(pwe);
					selection.addToSelection(g);
				}
				pressedObject = selection;
			} else {
				//Single object: select object and use dragelement specified by template
				selectObject(lastAdded);
				pressedObject = newTemplate.getDragElement(this);
			}

			newObject = newTemplate.getDragElement(this) == null ? null : newObjects[0];
			vPreviousX = ve.x;
			vPreviousY = ve.y;

			fireVPathwayEvent(new VPathwayEvent(this, lastAdded,
					VPathwayEventType.ELEMENT_ADDED));
			newTemplate.postInsert(newObjects);
		}
		setNewTemplate(null);
	}

	public void mouseEnter(MouseEvent e)
	{
		hoverManager.reset(e);
	}

	public void mouseExit(MouseEvent e)
	{
		hoverManager.stop();
	}

	/**
	 * Select all objects of the given class
	 *
	 * @param c
	 *            The class of the objects to be selected
	 */
	void selectObjects(Class<?> c)
	{
		clearSelection();
		selection.startSelecting();
		for (VPathwayElement vpe : getDrawingObjects())
		{
			if (c == null || c.isInstance(vpe))
			{
				selection.addToSelection(vpe);
			}
		}
		selection.stopSelecting();
		redrawDirtyRect();
	}

	void selectAll()
	{
		selectObjects(null);
	}

	/**
	 * Responds to ctrl/command-G. First checks for current status of selection with
	 * respect to grouping. If selection is already grouped (members of the same
	 * parent group), then the highest-level (parent) group is removed along
	 * with all references to the group. If the selection is not a uniform
	 * group, then a new group is created and each member or groups of members
	 * is set to reference the new group.
	 *
	 * @param selection
	 * @return If a group is created, or if the items were added to a new group,
	 * this group is returned. If a group is removed, this method will return
	 * <code>null</code>.
	 */
	public Group toggleGroup(List<Graphics> selection)
	{
		// groupSelection will be set to true if we are going to add / expand a group,
		// false if we're going to remove a group.
		boolean groupSelection = false;
		Set<String> groupRefList = new HashSet<String>();

		/**
		 * Check group status of current selection
		 */
		for (Graphics g : selection)
		{
			PathwayElement pe = g.getPathwayElement();
			String ref = pe.getGroupRef();
			// If not a group
			if (pe.getObjectType() != ObjectType.GROUP)
			{
				// and not a member of a group
				if (ref == null)
				{
					// then selection needs to be grouped
					groupSelection = true;
				}
				// and is a member of a group
				else
				{
					// recursively get all parent group references. 
					while (ref != null)
					{  
						groupRefList.add(ref);
						PathwayElement refGroup = data.getGroupById(ref);
						ref = refGroup.getGroupRef();
					}
				}
			}
		}
		// If more than one group is present in selection, then selection needs to be grouped
		if (groupRefList.size() > 1)
		{
			groupSelection = true;
		}

		//In all cases, any old groups in selection should be disolved.
		for (String id : groupRefList)
		{
			PathwayElement e = data.getGroupById(id);
			if (e != null) data.remove(e);
		}

		// If selection was defined as a single group, then we're done.
		// clear the selection from view
		if (!groupSelection)
		{
			clearSelection();
		}
		// Otherwise, a new group will be formed, replacing any former groups.
		// No more nested or overlapping groups!
		else
		{
			// Form new group with all selected elements
			PathwayElement group = PathwayElement.createPathwayElement(ObjectType.GROUP);
			data.add(group);
			group.setGroupStyle(GroupStyle.NONE);
			String id = group.createGroupId();

			for (Graphics g : selection)
			{
				PathwayElement pe = g.getPathwayElement();
				pe.setGroupRef(id);
			}

			// Select new group in view
			Graphics vg = getPathwayElementView(group);
			if(vg != null) {
				clearSelection();
				selectObject(vg);
			}
			return (Group)vg;
		}
		return null;
	}
	
	private void fireHyperlinkUpdate(VPathwayElement vpe) {
		int type;         
		if(stateEntered && stateCtrl) {
			type = VElementMouseEvent.TYPE_MOUSE_SHOWHAND;
		} else {
			type = VElementMouseEvent.TYPE_MOUSE_NOTSHOWHAND;
		}         
		fireVElementMouseEvent(new VElementMouseEvent(this, type, vpe));
	}

	public void keyPressed(KeyEvent e)
	{
		// Use registerKeyboardActions
		if(KeyEvent.CTRL == e.getKeyCode()) {
			stateCtrl = true;
			if(lastEnteredElement != null) {
				fireHyperlinkUpdate(lastEnteredElement);
			}
		}
	}

	//TODO: should use Toolkit.getMenuShortcutKeyMask(), but
	// that doesn't work in headless mode so screws up automated testing.
	// solution: define keyboard shortcuts elsewhere
	public static final KeyStroke KEY_SELECT_DATA_NODES = KeyStroke
			.getKeyStroke(java.awt.event.KeyEvent.VK_D,
					java.awt.Event.CTRL_MASK);

	public static final KeyStroke KEY_BOLD = KeyStroke
	.getKeyStroke(java.awt.event.KeyEvent.VK_B,
			java.awt.Event.CTRL_MASK);
	
	public static final KeyStroke KEY_ITALIC = KeyStroke
	.getKeyStroke(java.awt.event.KeyEvent.VK_I,
			java.awt.Event.CTRL_MASK);	
	
	public static final KeyStroke KEY_MOVERIGHT = KeyStroke.getKeyStroke(
			java.awt.event.KeyEvent.VK_RIGHT, 0);

	public static final KeyStroke KEY_MOVELEFT = KeyStroke.getKeyStroke(
			java.awt.event.KeyEvent.VK_LEFT, 0);

	public static final KeyStroke KEY_MOVEUP = KeyStroke.getKeyStroke(
			java.awt.event.KeyEvent.VK_UP, 0);

	public static final KeyStroke KEY_MOVEDOWN = KeyStroke.getKeyStroke(
			java.awt.event.KeyEvent.VK_DOWN, 0);

	public static final KeyStroke KEY_MOVERIGHT_SHIFT = KeyStroke.getKeyStroke(
			java.awt.event.KeyEvent.VK_RIGHT, java.awt.Event.SHIFT_MASK);

	public static final KeyStroke KEY_MOVELEFT_SHIFT = KeyStroke.getKeyStroke(
			java.awt.event.KeyEvent.VK_LEFT, java.awt.Event.SHIFT_MASK);

	public static final KeyStroke KEY_MOVEUP_SHIFT = KeyStroke.getKeyStroke(
			java.awt.event.KeyEvent.VK_UP, java.awt.Event.SHIFT_MASK);

	public static final KeyStroke KEY_MOVEDOWN_SHIFT = KeyStroke.getKeyStroke(
			java.awt.event.KeyEvent.VK_DOWN, java.awt.Event.SHIFT_MASK);

	/**
	 * Get the view actions, a class where several actions related to the view
	 * are stored (delete, select) and where other actions can be registered to
	 * a group (e.g. a group that will be disabled when edit-mode is turned off)
	 *
	 * @return an instance of the {@link ViewActions} class
	 */
	public ViewActions getViewActions()
	{
		return viewActions;
	}

	/**
	 * Several {@link Action}s related to the view
	 */
	private ViewActions viewActions;

	// Convenience method to register an action that has an accelerator key
	private void registerKeyboardAction(Action a)
	{
		if (parent == null) return;
		KeyStroke key = (KeyStroke) a.getValue(Action.ACCELERATOR_KEY);
		if (key == null)
			throw new RuntimeException("Action " + a
					+ " must have value ACCELERATOR_KEY set");
		parent.registerKeyboardAction(key, a);
	}

	public void registerKeyboardActions(Engine engine)
	{
		viewActions = new ViewActions(engine, this);

		if (parent != null)
		{
			registerKeyboardAction(viewActions.copy);
			registerKeyboardAction(viewActions.paste);
			parent.registerKeyboardAction(KEY_SELECT_DATA_NODES,
					viewActions.selectDataNodes);
			registerKeyboardAction(viewActions.toggleGroup);
			registerKeyboardAction(viewActions.toggleComplex);
			registerKeyboardAction(viewActions.selectAll);
			registerKeyboardAction(viewActions.delete1);
			registerKeyboardAction(viewActions.delete2);
			registerKeyboardAction(viewActions.undo);
			registerKeyboardAction(viewActions.addAnchor);
			registerKeyboardAction(viewActions.orderBringToFront);
			registerKeyboardAction(viewActions.orderSendToBack);
			registerKeyboardAction(viewActions.orderUp);
			registerKeyboardAction(viewActions.orderDown);
			registerKeyboardAction(viewActions.showUnlinked);
			parent.registerKeyboardAction(KEY_MOVERIGHT, new KeyMoveAction(
					engine,
					KEY_MOVERIGHT));
			parent.registerKeyboardAction(KEY_MOVERIGHT_SHIFT, new KeyMoveAction(
					engine,
					KEY_MOVERIGHT_SHIFT));
			parent.registerKeyboardAction(KEY_MOVELEFT, new KeyMoveAction(
					engine,
					KEY_MOVELEFT));
			parent.registerKeyboardAction(KEY_MOVELEFT_SHIFT, new KeyMoveAction(
					engine,
					KEY_MOVELEFT_SHIFT));
			parent
					.registerKeyboardAction(KEY_MOVEUP, new KeyMoveAction(
							engine,
							KEY_MOVEUP));
			parent.registerKeyboardAction(KEY_MOVEUP_SHIFT, new KeyMoveAction(
					engine,
					KEY_MOVEUP_SHIFT));
			parent.registerKeyboardAction(KEY_MOVEDOWN, new KeyMoveAction(
					engine,
					KEY_MOVEDOWN));
			parent.registerKeyboardAction(KEY_MOVEDOWN_SHIFT, new KeyMoveAction(
					engine,
					KEY_MOVEDOWN_SHIFT));
			parent.registerKeyboardAction(KEY_BOLD, new TextFormattingAction(
					engine,
					KEY_BOLD));
			parent.registerKeyboardAction(KEY_ITALIC, new TextFormattingAction(
					engine,
					KEY_ITALIC));
		}
	}

	public void keyReleased(KeyEvent e)
	{
		// use registerKeyboardActions
		if(KeyEvent.CTRL == e.getKeyCode()) {
			stateCtrl = false;
			if(lastEnteredElement != null) {
				fireHyperlinkUpdate(lastEnteredElement);
			}
		}
	}

	/**
	 * Removes the GmmlDrawingObjects in the ArrayList from the drawing<BR>
	 * Does not remove the model representation!
	 *
	 * @param toRemove
	 *            The List containing the objects to be removed
	 */
	public void removeDrawingObjects(List<VPathwayElement> toRemove)
	{
		removeDrawingObjects(toRemove, false);
	}

	/**
	 * Removes the GmmlDrawingObjects in the ArrayList from the drawing
	 *
	 * @param toRemove
	 *            The List containing the objects to be removed
	 * @param removeFromModel
	 *            Whether to remove the model representation or not
	 */
	public void removeDrawingObjects(List<VPathwayElement> toRemove,
			boolean removeFromModel)
	{
		for (VPathwayElement o : toRemove)
		{
			removeDrawingObject(o, removeFromModel);
		}
		selection.fitToSelection();
		cleanUp();
	}

	public void removeDrawingObject(VPathwayElement toRemove,
			boolean removeFromModel)
	{
		if (toRemove != null){
			selection.removeFromSelection(toRemove); // Remove from selection
			toRemove.destroy(); // Object will remove itself from the drawing
			if (removeFromModel)
			{
				if (toRemove instanceof Graphics)
				{
					//Remove the model object
					data.remove(((Graphics) toRemove).getPathwayElement());
				}
			}
			cleanUp();
		}
	}

	private Graphics lastAdded = null;

	public void pathwayModified(PathwayEvent e)
	{
		switch (e.getType())
		{
			case PathwayEvent.DELETED:
				Graphics deleted = getPathwayElementView(e.getAffectedData());
				if (deleted != null)
				{
					if (deleted.getPathwayElement() instanceof MLine) {
						removeRefFromConnectingAnchors(deleted.getPathwayElement().getMStart().getGraphRef(), deleted.getPathwayElement().getMEnd().getGraphRef());
					}
					deleted.markDirty();
					removeDrawingObject(deleted, false);
				}
				break;
			case PathwayEvent.ADDED:
				lastAdded = fromModelElement(e.getAffectedData());
				if (lastAdded != null) {
					lastAdded.markDirty();
				}
				break;
			case PathwayEvent.RESIZED:
				if (parent != null)
				{	
					parent.resized();
				}
				break;
		}
		addScheduled();
		cleanUp();
	}

    /*
    * when line deleted need to:
    *   see if other lines contain same graphIds (this means that 2 different lines are attached to the same anchor)
    *      if so - ignore graphId
    *      otherwise - loop through pathway and find any lines with anchors that contain GraphIds for the deleted line and remove.
    */
    private void removeRefFromConnectingAnchors(String graphId1, String graphId2) {
        if (graphId1 == null && (graphId2 == null)) {
            return;
        }
        for (PathwayElement element : getPathwayModel().getDataObjects()) {
             if (element instanceof MLine) {
                 for (MPoint point:element.getMPoints()) {
                      if (point.getGraphRef() == null) {
                          // skip point
                      } else if (graphId1 != null && point.getGraphRef().equals(graphId1)) {
                          graphId1 = null;
                      } else if (graphId2 != null && point.getGraphRef().equals(graphId2)) {
                          graphId2 = null;
                      }
                 }
             }
        }
        if (graphId1 == null && (graphId2 == null)) {
            return;
        }
        for (PathwayElement element : getPathwayModel().getDataObjects()) {
             if (element instanceof MLine) {
                 for (MAnchor anchor:element.getMAnchors()) {
                     if (anchor.getGraphId() != null && (anchor.getGraphId().equals(graphId1) || anchor.getGraphId().equals(graphId2))) {
                          anchor.setGraphId(null);
                      }
                 }
             }
        }
    }

    /**
	 * Calculate the board size. Calls {@link VPathwayElement#getVBounds()} for every
	 * element and adds all results together to obtain the board size
	 */
	public Dimension calculateVSize() {
		Rectangle2D bounds = new Rectangle2D.Double();
		for(VPathwayElement e : drawingObjects) {
			bounds.add(e.getVBounds());
		}
		return new Dimension((int)bounds.getWidth() + 10, (int)bounds.getHeight() + 10);
	}

	/**
	 * Makes a copy of all PathwayElements in current selection, and puts them
	 * in the global clipboard.
	 */
	public void copyToClipboard()
	{
		List<PathwayElement> result = new ArrayList<PathwayElement>();
		for (VPathwayElement g : drawingObjects)
		{
			if (g.isSelected() && g instanceof Graphics
					&& !(g instanceof SelectionBox))
			{
				result.add(((Graphics) g).gdata.copy());
			}
		}
		if (result.size() > 0)
		{
			if (parent != null) parent.copyToClipboard(getPathwayModel(), result);
		}
	}

	/**
	 * Handles aligning layoutTypes ALIGN_*
	 */
	private void alignGraphics(LayoutType alignType, List<Graphics> gs)
	{
		// first sort either horizontally or vertically
		switch (alignType)
		{
		case ALIGN_CENTERY:
		case ALIGN_TOP:
			Collections.sort(gs, new YComparator());
			break;
		case ALIGN_LEFT:
		case ALIGN_CENTERX:
			Collections.sort(gs, new XComparator());
			break;
		case ALIGN_BOTTOM:
			Collections.sort(gs, new YComparator());
			Collections.reverse(gs);
			break;
		case ALIGN_RIGHT:
			Collections.sort(gs, new XComparator());
			Collections.reverse(gs);
			break;
		default:
			throw new IllegalArgumentException("This method only handles ALIGN_* layoutTypes");
		}

		// The bounds of the model to view
		// translated shape
		Rectangle2D vBoundsFirst =
			gs.get(0).getVShape(true).getBounds2D();

		for (int i = 1; i < gs.size(); i++)
		{
			Graphics g = gs.get(i);
			Rectangle2D vBounds = g.getVShape(true).getBounds2D();

			switch (alignType)
			{
				case ALIGN_CENTERX:
					g.vMoveBy(vBoundsFirst.getCenterX()- vBounds.getCenterX(), 0);
				break;
				case ALIGN_CENTERY:
					g.vMoveBy(0, vBoundsFirst.getCenterY() - vBounds.getCenterY());
				break;
				case ALIGN_LEFT:
					g.vMoveBy(vBoundsFirst.getX() - vBounds.getX(), 0);
				break;
				case ALIGN_RIGHT:
					g.vMoveBy(vBoundsFirst.getMaxX() - vBounds.getMaxX(), 0);
				break;
				case ALIGN_TOP:
					g.vMoveBy(0, vBoundsFirst.getY() - vBounds.getY());
				break;
				case ALIGN_BOTTOM:
					g.vMoveBy(0, vBoundsFirst.getMaxY() - vBounds.getMaxY());
				break;
			}
		}
	}

	/**
	 * Align, stack or scale selected objects based on user-selected layout type
	 */
	public void layoutSelected(LayoutType layoutType)
	{
		List<Graphics> selectedGraphics = getSelectedNonGroupGraphics();

		if (selectedGraphics.size() > 0)
		{
			undoManager.newAction(layoutType.getDescription());
			switch (layoutType)
			{
				case COMMON_WIDTH:
					scaleWidth(selectedGraphics);
					break;
				case COMMON_HEIGHT:
					scaleHeight(selectedGraphics);
					break;
				case ALIGN_CENTERX:
				case ALIGN_CENTERY:
				case ALIGN_TOP:
				case ALIGN_LEFT:
				case ALIGN_RIGHT:
				case ALIGN_BOTTOM:
					alignGraphics(layoutType, selectedGraphics);
					break;
				case STACK_BOTTOM:
				case STACK_TOP:
				case STACK_LEFT:
				case STACK_RIGHT:
				case STACK_CENTERX:
				case STACK_CENTERY:
					stackGraphics(layoutType, selectedGraphics);
					break;
			}

			selection.fitToSelection();
			redrawDirtyRect();
		}
	}

	/**
	 * Stacks a set of objects based on user-selected stack type
	 */
	private void stackGraphics(LayoutType stackType, List<Graphics> gs)
	{
		// first we sort the selected graphics, either horizontally or vertically
		switch (stackType)
		{
		case STACK_CENTERX:
		case STACK_LEFT:
		case STACK_RIGHT:
			Collections.sort(gs, new YComparator());
			break;
		case STACK_CENTERY:
		case STACK_TOP:
		case STACK_BOTTOM:
			Collections.sort(gs, new XComparator());
			break;
		default:
			throw new IllegalArgumentException("This method only handles STACK_* layoutTypes");
		}

		for (int i = 1; i < gs.size(); i++)
		{
			// Get the current and previous graphics objects
			Graphics eCurr = gs.get(i);
			Graphics ePrev = gs.get(i - 1);

			// Get the bounds of the model to view translated shapes
			Rectangle2D vBoundsPrev = ePrev.getVShape(true).getBounds2D();
			Rectangle2D vBoundsCurr = eCurr.getVShape(true).getBounds2D();
			switch (stackType)
			{
			case STACK_CENTERX:
				eCurr.vMoveBy(
						vBoundsPrev.getCenterX() - vBoundsCurr.getCenterX(),
						vBoundsPrev.getMaxY() - vBoundsCurr.getY());
				break;
			case STACK_CENTERY:
				eCurr.vMoveBy(
						vBoundsPrev.getMaxX() - vBoundsCurr.getX(),
						vBoundsPrev.getCenterY() - vBoundsCurr.getCenterY());
				break;
			case STACK_LEFT:
				eCurr.vMoveBy(
						vBoundsPrev.getX() - vBoundsCurr.getX(),
						vBoundsPrev.getMaxY() - vBoundsCurr.getY());
				break;
			case STACK_RIGHT:
				eCurr.vMoveBy(
						vBoundsPrev.getMaxX() - vBoundsCurr.getMaxX(),
						vBoundsPrev.getMaxY() - vBoundsCurr.getY());
				break;
			case STACK_TOP:
				eCurr.vMoveBy(
						vBoundsPrev.getMaxX() - vBoundsCurr.getX(),
						vBoundsPrev.getY() - vBoundsCurr.getY());
				break;
			case STACK_BOTTOM:
				eCurr.vMoveBy(
						vBoundsPrev.getMaxX() - vBoundsCurr.getX(),
						vBoundsPrev.getMaxY() - vBoundsCurr.getMaxY());
				break;
			}
		}
	}

	/**
	 * Scales a set of objects by max width
	 */
	private void scaleWidth(List<Graphics> gs)
	{
		double maxW = 0;
		Graphics gMax = null;
		for (Graphics g : gs)
		{
			Rectangle2D r = g.getVShape(true).getBounds2D();
			double w = Math.abs(r.getWidth());
			if (w > maxW)
			{
				gMax = g;
				maxW = w;
			}
		}
		for (Graphics g : gs)
		{
			if (g == gMax)
				continue;

			Rectangle2D r = g.getVShape(true).getBounds2D();
			double oldWidth = r.getWidth();
			if (oldWidth < 0)
			{
				r.setRect(r.getX(), r.getY(), -(maxW), r.getHeight());
				g.setVScaleRectangle(r);
				g.vMoveBy((oldWidth + maxW) / 2, 0);
			} else
			{
				r.setRect(r.getX(), r.getY(), maxW, r.getHeight());
				g.setVScaleRectangle(r);
				g.vMoveBy((oldWidth - maxW) / 2, 0);
			}
		}
	}

	/**
	 * Scales selected objects by max height
	 */
	private void scaleHeight(List<Graphics> gs)
	{
		double maxH = 0;
		Graphics gMax = null;
		for (Graphics g : gs)
		{
			Rectangle2D r = g.getVShape(true).getBounds2D();
			double h = Math.abs(r.getHeight());
			if (h > maxH)
			{
				gMax = g;
				maxH = h;
			}
		}
		for (Graphics g : gs)
		{
			if (g == gMax)
				continue;

			Rectangle2D r = g.getVShape(true).getBounds2D();
			double oldHeight = r.getHeight();
			if (oldHeight < 0)
			{
				r.setRect(r.getX(), r.getY(), r.getWidth(), -(maxH));
				g.setVScaleRectangle(r);
				g.vMoveBy(0, (maxH + oldHeight) / 2);
			} else
			{
				r.setRect(r.getX(), r.getY(), r.getWidth(), maxH);
				g.setVScaleRectangle(r);
				g.vMoveBy(0, (oldHeight - maxH) / 2);
			}
		}
	}

	/**
	 * Move a set of graphics to the top in the z-order stack
	 */
	public void moveGraphicsTop (List<Graphics> gs)
	{
		Collections.sort (gs, new ZComparator());
		int base = getPathwayModel().getMaxZOrder() + 1;
		for (Graphics g : gs)
		{
			g.gdata.setZOrder(base++);
		}
	}

	/**
	 * Move a set of graphics to the bottom in the z-order stack
	 */
	public void moveGraphicsBottom (List<Graphics> gs)
	{
		Collections.sort (gs, new ZComparator());
		int base = getPathwayModel().getMinZOrder() - gs.size() - 1;
		for (Graphics g : gs)
		{
			g.gdata.setZOrder(base++);
		}
	}

	/**
	 * Looks for overlapping graphics with a higher z-order
	 * and moves g on top of that.
	 */
	public void moveGraphicsUp (List<Graphics> gs)
	{
		//TODO: Doesn't really work very well with multiple selections
		for (Graphics g : gs)
		{
			// make sure there is enough space between g and the next
			autoRenumberZOrder();

			int order = g.gdata.getZOrder();
			Graphics nextGraphics = null;
			int nextZ = order;
			for (Graphics i : getOverlappingGraphics(g))
			{
				int iorder = i.gdata.getZOrder();
				if (nextGraphics == null && iorder > nextZ)
				{
					nextZ = iorder;
					nextGraphics = i;
				}
				else if (nextGraphics != null && iorder < nextZ && iorder > order)
				{
					nextZ = iorder;
					nextGraphics = i;
				}
			}
			g.gdata.setZOrder (nextZ + 1);
		}
	}

	/**
	 * makes sure there is always a minimum spacing of two between
	 * two consecutive elements, so that we can freely move items in between
	 */
	private void autoRenumberZOrder()
	{
		List<Graphics> elts = new ArrayList<Graphics>();
		for (VPathwayElement vp : drawingObjects)
		{
			if (vp instanceof Graphics)
			{
				elts.add ((Graphics)vp);
			}
		}
		if (elts.size() < 2) return; // nothing to renumber
		Collections.sort (elts, new ZComparator());

		final int spacing = 2;

		int waterLevel = elts.get(0).gdata.getZOrder();
		for (int i = 1; i < elts.size(); ++i)
		{
			Graphics curr = elts.get (i);
			if (curr.gdata.getZOrder() - waterLevel < spacing)
			{
				curr.gdata.setZOrder(waterLevel + spacing);
			}
			waterLevel = curr.gdata.getZOrder();
		}
	}

		/**
	 * Looks for overlapping graphics with a lower z-order
	 * and moves g on under that.
	 */
	public void moveGraphicsDown (List<Graphics> gs)
	{
		//TODO: Doesn't really work very well with multiple selections
		for (Graphics g : gs)
		{
			// make sure there is enough space between g and the previous
			autoRenumberZOrder();

			int order = g.gdata.getZOrder();
			Graphics nextGraphics = null;
			int nextZ = order;
			for (Graphics i : getOverlappingGraphics(g))
			{
				int iorder = i.gdata.getZOrder();
				if (nextGraphics == null && iorder < nextZ)
				{
					nextZ = iorder;
					nextGraphics = i;
				}
				else if (nextGraphics != null && iorder > nextZ && iorder < order)
				{
					nextZ = iorder;
					nextGraphics = i;
				}
			}
			g.gdata.setZOrder (nextZ - 1);
		}
	}
	/**
	 * return a list of Graphics that overlap g.
	 * Note that the intersection of bounding rectangles is used,
	 * so the returned list is only an approximation for rounded shapes.
	 */
	public List<Graphics> getOverlappingGraphics(Graphics g)
	{
		List<Graphics> result = new ArrayList<Graphics>();
		Rectangle2D r1 = g.getVBounds();

		for (VPathwayElement ve : drawingObjects)
		{
			if (ve instanceof Graphics && ve != g)
			{
				Graphics i = (Graphics)ve;
				if (r1.intersects(ve.getVBounds()))
				{
					result.add (i);
				}
			}
		}
		return result;
	}

	/**
	 * Get all elements of the class Graphics that are currently selected
	 *
	 * @return
	 */
	public List<Graphics> getSelectedGraphics()
	{
		List<Graphics> result = new ArrayList<Graphics>();
		for (VPathwayElement g : drawingObjects)
		{
			if (g.isSelected() && g instanceof Graphics
					&& !(g instanceof SelectionBox))
			{
				result.add((Graphics) g);
			}
		}
		return result;
	}

	/**
	 * Get all elements of the class Graphics that are currently selected, excluding Groups
	 *
	 * @return
	 */
	public List<Graphics> getSelectedNonGroupGraphics()
	{
		List<Graphics> result = new ArrayList<Graphics>();
		for (VPathwayElement g : drawingObjects)
		{
			if (g.isSelected() && g instanceof Graphics
					&& !(g instanceof SelectionBox) && !((g instanceof Group)))
			{
				result.add((Graphics) g);
			}
		}
		return result;
	}

	/**
	 * Get all selected elements (includes non-Graphics, e.g. Handles)
	 * @return
	 */
	public Set<VPathwayElement> getSelectedPathwayElements() {
		return selection.getSelection();
	}

	private void generatePasteId(String oldId, Set<String> idset, Map<String, String> idmap,
			Set<String> newids)
	{
		if (oldId != null)
		{
			String x;
			do
			{
				/*
				 * generate a unique id. at the same time, check that it is not
				 * equal to one of the unique ids that we generated since the
				 * start of this method
				 */
				x = data.getUniqueId(idset);
			} while (newids.contains(x));
			newids.add(x); // make sure we don't generate this one
			// again

			idmap.put(oldId, x);
		}
	}

	/**
	 * Generate new id's for a bunch of elements to be pasted, but do not actually set them.
	 * Instead, store these new ids in a map, so that we can later update
	 * both the graphIds and graphReferences,
	 * as well as groupIds and groupReferences.
	 *
	 * idMap and newIds should be an empty map / set.
	 * It will be filled by this method.
	 */
	private void generateNewIds(List<PathwayElement> elements,
			Map<String, String> idmap, Set<String> newids)
	{
		for (PathwayElement o : elements)
		{
			String id = o.getGraphId();
			String groupId = o.getGroupId();
			generatePasteId(id, data.getGraphIds(), idmap, newids);
			generatePasteId(groupId, data.getGroupIds(), idmap, newids);

			//For a line, also process the point ids
			if(o.getObjectType() == ObjectType.LINE) {
				for(MPoint mp : o.getMPoints())
					generatePasteId(mp.getGraphId(), data.getGraphIds(), idmap, newids);
				for(MAnchor ma : o.getMAnchors())
					generatePasteId(ma.getGraphId(), data.getGraphIds(), idmap, newids);
			}
		}
	}

	public void paste(List<PathwayElement> elements) {
		paste(elements, 0, 0);
	}

	/**
	 * Updates all id's and references of a single PathwayElement, using
	 * the provided idMap.
	 *
	 * This will
	 * - replace groupId of elements
	 * - replace graphId of elements, anchors and points
	 * - replace graphRefs if it's in the map, otherwise set to null
	 * - replace groupRegs if it's in the map, otherwise set to null
	 */
	private void replaceIdsAndRefs(PathwayElement p, Map<String, String> idmap)
	{
		// set new unique id
		if (p.getGraphId() != null)
		{
			p.setGraphId(idmap.get(p.getGraphId()));
		}
		for(MPoint mp : p.getMPoints()) {
			mp.setGraphId(idmap.get(mp.getGraphId()));
		}
		for(MAnchor ma : p.getMAnchors()) {
			ma.setGraphId(idmap.get(ma.getGraphId()));
		}
		// set new group id
		String gid = p.getGroupId();
		if (gid != null)
		{
			p.setGroupId(idmap.get(gid));
		}
		// update graphref
		String y = p.getStartGraphRef();
		if (y != null)
		{
			if (idmap.containsKey(y))
			{
				p.setStartGraphRef(idmap.get(y));
			} else
			{
				p.setStartGraphRef(null);
			}
		}
		y = p.getEndGraphRef();
		if (y != null)
		{
			if (idmap.containsKey(y))
			{
				p.setEndGraphRef(idmap.get(y));
			} else
			{
				p.setEndGraphRef(null);
			}
		}
		y = p.getGraphRef();
		if (y != null)
		{
			if (idmap.containsKey(y))
			{
				p.setGraphRef(idmap.get(y));
			} 
			// If the ref points to an item outside the selection, keep using original!
		}		
		// update groupref
		String groupRef = p.getGroupRef();
		if (groupRef != null)
		{
			if (idmap.containsKey(groupRef))
			{
				p.setGroupRef(idmap.get(groupRef));
			} else
			{
				p.setGroupRef(null);
			}
		}
	}
	
	public void paste(List<PathwayElement> elements, double xShift, double yShift) {
		undoManager.newAction("Paste");
		clearSelection();
		
		Map<String, String> idmap = new HashMap<String, String>();
		Set<String> newids = new HashSet<String>();
		
		// Step 1: generate new unique ids for copied items
		generateNewIds (elements, idmap, newids);
		
		// Step 2: do the actual copying
		for (PathwayElement o : elements)
		{
			if (o.getObjectType() == ObjectType.INFOBOX) {
				// we skip infobox because it should be unique in a pathway
				continue;
			}

			if (o.getObjectType() == ObjectType.BIOPAX) {
				// Merge the copied biopax elements with existing
				data.mergeBiopax(o);
				continue;
			}

			lastAdded = null;

			if(o.getObjectType() == ObjectType.LINE) {
				for (MPoint mp : o.getMPoints())
				{
					mp.setX(mp.getX() + xShift);
					mp.setY(mp.getY() + yShift);
				}
			} else {
				o.setMLeft(o.getMLeft() + xShift);
				o.setMTop(o.getMTop() + yShift);
			}

			// make another copy to preserve clipboard contents for next paste
			PathwayElement p = o.copy();

			// use the idMap to set consistent new id's
			replaceIdsAndRefs (p, idmap);

			data.add(p); // causes lastAdded to be set
			lastAdded.select();
			if (!(lastAdded instanceof Group)){ // avoids "double selecting" grouped objects
				selection.addToSelection(lastAdded);
			}
		}

		// Step 3: refresh connector shapes
		for(PathwayElement o : elements) {
			if(o.getObjectType() == ObjectType.LINE) {
				((MLine)o).getConnectorShape().recalculateShape(((MLine)o));
			}
		}
		moveGraphicsTop(getSelectedGraphics());
		redrawDirtyRect();
	}

	public void pasteFromClipboard()
	{
		if (isEditMode())
		{ // Only paste in edit mode
			if (parent != null) parent.pasteFromClipboard();
		}
	}
	
	/**
	 * paste from clip board at the current cursor position
	 */
	public void positionPasteFromClipboard(Point cursorPosition) {
		if(isEditMode()) 
		{
			if (parent != null) parent.positionPasteFromClipboard(cursorPosition);
		}
	}

	private List<VPathwayListener> listeners = new ArrayList<VPathwayListener>();

	public void addVPathwayListener(VPathwayListener l)
	{
		if (!listeners.contains(l))
		{
			listeners.add(l);
		}
	}

	public void removeVPathwayListener(VPathwayListener l)
	{
		Logger.log.trace(listeners.remove(l) + ": " + l);
	}

	private List<VElementMouseListener> elementListeners = new ArrayList<VElementMouseListener>();

	public void addVElementMouseListener(VElementMouseListener l) {
		if(!elementListeners.contains(l)) {
			elementListeners.add(l);
		}
	}

	public void removeVElementMouseListener(VElementMouseListener l) {
		elementListeners.remove(l);
	}

	protected void fireVElementMouseEvent(VElementMouseEvent e)
	{
		for (VElementMouseListener l : elementListeners)
		{
			l.vElementMouseEvent(e);
		}
	}

	/**
	 * Adds a {@link SelectionListener} to the SelectionBox of this VPathway
	 *
	 * @param l
	 *            The SelectionListener to add
	 */
	public void addSelectionListener(SelectionListener l)
	{
		selection.addListener(l);
	}

	/**
	 * Removes a {@link SelectionListener} from the SelectionBox of this
	 * VPathway
	 *
	 * @param l
	 *            The SelectionListener to remove
	 */
	public void removeSelectionListener(SelectionListener l)
	{
		selection.removeListener(l);
	}

	protected void fireVPathwayEvent(VPathwayEvent e)
	{
		for (VPathwayListener l : listeners)
		{
			l.vPathwayEvent(e);
		}
	}

	/**
	 * helper method to convert view coordinates to model coordinates
	 */
	public double mFromV(double v)
	{
		return v / zoomFactor;
	}

	/**
	 * helper method to convert model coordinates to view coordinates
	 */
	public double vFromM(double m)
	{
		return m * zoomFactor;
	}

	private AffineTransform vFromM = new AffineTransform();

	public java.awt.Shape vFromM(java.awt.Shape s) {
		vFromM.setToScale(zoomFactor, zoomFactor);
		return vFromM.createTransformedShape(s);
	}
	/**
	 * Get width of entire Pathway view (taking into account zoom)
	 */
	public int getVWidth()
	{
		return data == null ? 0 : (int) vFromM(data.getMappInfo()
				.getMBoardWidth());
	}

	/**
	 * Get height of entire Pathway view (taking into account zoom)
	 */
	public int getVHeight()
	{
		return data == null ? 0 : (int) vFromM(data.getMappInfo()
				.getMBoardHeight());
	}

	/** sorts graphics by VCenterY */
	public static class YComparator implements Comparator<Graphics>
	{
		public int compare(Graphics g1, Graphics g2)
		{
			if (g1.getVCenterY() == g2.getVCenterY())
				return 0;
			else if (g1.getVCenterY() < g2.getVCenterY())
				return -1;
			else
				return 1;
		}
	}

	/** sorts graphics by VCenterX */
	public static class XComparator implements Comparator<Graphics>
	{
		public int compare(Graphics g1, Graphics g2)
		{
			if (g1.getVCenterX() == g2.getVCenterX())
				return 0;
			else if (g1.getVCenterX() < g2.getVCenterX())
				return -1;
			else
				return 1;
		}
	}

	/** sorts Graphics by ZOrder */
	public static class ZComparator implements Comparator<Graphics>
	{
		public int compare(Graphics g1, Graphics g2)
		{
			return g1.gdata.getZOrder() - g2.gdata.getZOrder();
		}
	}

	private UndoManager undoManager = new UndoManager();

	/**
	 * Activates the undo manager by providing an engine
	 * to which the undo actions will be applied. If this
	 * method is not called, the undo manager will not
	 * record any undo actions.
	 */
	public void activateUndoManager(Engine engine) {
		undoManager.activate(engine);
	}

	/**
	 * returns undoManager owned by this instance of VPathway.
	 */
	public UndoManager getUndoManager()
	{
		return undoManager;
	}

	/*
	 * To be called only by undo.
	 */
	/*
	 * public void setUndoManager(UndoManager value) { undoManager = value; }
	 */
	public void undo()
	{
		undoManager.undo();
	}

	private boolean disposed = false;
	/**
	 * free all resources (such as listeners) held by this class.
	 * Owners of this class must explicitly dispose of it to clean up.
	 */
	public void dispose()
	{
		assert (!disposed);
		for (VPathwayElement elt : getDrawingObjects())
		{
			elt.destroy();
		}
		cleanUp();
		if (data != null) data.removeListener(this);
		listeners.clear();
		selection.getListeners().clear();
		viewActions = null;
		if (parent != null) parent.dispose();
		parent = null; // disconnect from VPathwaySwing
		undoManager.dispose();
		undoManager = null;
		hoverManager.stop();
		disposed = true;
	}

	/**
	 * When adding elements to a pathway, they are not added immediately
	 * but placed in a temporary array. This to prevent concurrent 
	 * modification of the main elements array. 
	 * This method adds the elements that are scheduled to be added.
	 */
	void addScheduled()
	{
		for (VPathwayElement elt : toAdd)
		{
			if (!drawingObjects.contains(elt))
			{ // Don't add duplicates!
				drawingObjects.add(elt);
			}
		}
		toAdd.clear();
	}

	private void cleanUp()
	{
		for (Iterator<VPathwayElement> i = drawingObjects.iterator(); i.hasNext(); )
		{
			VPathwayElement elt = i.next();
			if (elt.toBeRemoved()) { i.remove(); }
		}
	}

	/**
	 * Move multiple elements together (either a group or a selection).
	 * If a State is contained together with its parent DataNode, then the state is not moved. 
	 */
	public void moveMultipleElements (Collection<? extends VPathwayElement> toMove, double vdx, double vdy)
	{
		// collect all graphIds in selection
		Set<String> eltIds = new HashSet<String>();
		for (VPathwayElement o : toMove)
			if (o instanceof Graphics) 
				{
					String id = ((Graphics)o).getPathwayElement().getGraphId();
					if (id != null) eltIds.add(id);
				}
		
		for (VPathwayElement o : toMove) 
		{
			// skip if parent of state is also in selection.
			if (o instanceof State && eltIds.contains (((State)o).getPathwayElement().getGraphRef()))
					continue;

			if(o instanceof Graphics) {
				o.vMoveBy(vdx, vdy);
			}
		}
	}

}