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Core visualization support for the JUNG project
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/*
 * Copyright (c) 2005, The JUNG Authors
 * All rights reserved.
 *
 * This software is open-source under the BSD license; see either "license.txt"
 * or https://github.com/jrtom/jung/blob/master/LICENSE for a description.
 *
 * Created on Aug 23, 2005
 */

package edu.uci.ics.jung.visualization.layout;

import java.awt.geom.Point2D;
import java.util.ArrayList;
import java.util.List;

import javax.swing.event.ChangeListener;

import com.google.common.base.Function;
import com.google.common.base.Functions;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;

import edu.uci.ics.jung.algorithms.layout.Layout;
import edu.uci.ics.jung.algorithms.layout.LayoutDecorator;
import edu.uci.ics.jung.algorithms.util.IterativeContext;
import edu.uci.ics.jung.graph.Graph;
import edu.uci.ics.jung.visualization.util.Caching;
import edu.uci.ics.jung.visualization.util.ChangeEventSupport;
import edu.uci.ics.jung.visualization.util.DefaultChangeEventSupport;

/**
 * A LayoutDecorator that fires ChangeEvents when certain methods 
 * are called. Used to wrap a Layout so that the visualization
 * components can be notified of changes.
 * 
 * @see LayoutDecorator
 * @author Tom Nelson 
 *
 */
public class ObservableCachingLayout extends LayoutDecorator 
	implements ChangeEventSupport, Caching, LayoutEventSupport {
    
    protected ChangeEventSupport changeSupport = new DefaultChangeEventSupport(this);
    
    protected LoadingCache locations;
    
    private List> layoutChangeListeners = 
    	new ArrayList>();

    public ObservableCachingLayout(Layout delegate) {
    	super(delegate);
		Function chain = Functions. compose(
				new Function() {
					public Point2D apply(Point2D p) {
						return (Point2D) p.clone();
					}
				},
				delegate);
		this.locations = CacheBuilder.newBuilder().build(CacheLoader.from(chain));
    }
    
    @Override
    public void step() {
    	super.step();
    	fireStateChanged();
    }

	@Override
    public void initialize() {
		super.initialize();
		fireStateChanged();
	}
	
    @Override
    public boolean done() {
    	if(delegate instanceof IterativeContext) {
    		return ((IterativeContext)delegate).done();
    	}
    	return true;
    }


	@Override
    public void setLocation(V v, Point2D location) {
		super.setLocation(v, location);
		fireStateChanged();
		fireLayoutChanged(v);
	}

    public void addChangeListener(ChangeListener l) {
        changeSupport.addChangeListener(l);
    }

    public void removeChangeListener(ChangeListener l) {
        changeSupport.removeChangeListener(l);
    }

    public ChangeListener[] getChangeListeners() {
        return changeSupport.getChangeListeners();
    }

    public void fireStateChanged() {
        changeSupport.fireStateChanged();
    }
    
    @Override
    public void setGraph(Graph graph) {
        delegate.setGraph(graph);
    }

	public void clear() {
		this.locations.invalidateAll();
	}

	public void init() {
	}

	public Point2D apply(V v) {
		return locations.getUnchecked(v);
	}

	private void fireLayoutChanged(V v) {
		LayoutEvent evt = new LayoutEvent(v, this.getGraph());
		for(LayoutChangeListener listener : layoutChangeListeners) {
			listener.layoutChanged(evt);
		}
	}
	
	public void addLayoutChangeListener(LayoutChangeListener listener) {
		layoutChangeListeners.add(listener);
		
	}

	public void removeLayoutChangeListener(LayoutChangeListener listener) {
		layoutChangeListeners.remove(listener);
		
	}
}