// $Id: ChangeRegistry.java,v 1.7 2004/08/25 20:28:29 mvw Exp $
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// software and its documentation without fee, and without a written
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// File: ChangeRegistry.java
// Classes: ChangeRegistry
// Original Author: thorsten Jun 2000
// $Id: ChangeRegistry.java,v 1.7 2004/08/25 20:28:29 mvw Exp $

package org.argouml.util;

import org.argouml.kernel.ProjectManager;

import org.tigris.gef.graph.GraphEvent;
import org.tigris.gef.graph.GraphListener;

/** 
 * This class holds the information about the "change flag" of 
 * the current project. Initially, the "change flag" is clear, 
 * which means that there is nothing in the project to save. 
 * The "change flag" is set by every change made to its diagrams, 
 * which means that the project becomes 'dirty', i.e. it needs saving. 
 *
 * @see org.argouml.kernel.Project
 */
public class ChangeRegistry implements GraphListener
{
    private boolean changeFlag;

    /**
     * The constructor.
     * 
     */
    public ChangeRegistry() { changeFlag = false; }

    /**
     * Changes save state / notifies gui.
     *
     * @param newValue true means that the project needs to be saved. 
     *                 False means that there is nothing to save.
     */
    public void setChangeFlag( boolean newValue ) {
		
        boolean oldValue = changeFlag;
        changeFlag = newValue;                
        
	if (oldValue != newValue) {
	    // notify the gui to put a * on the title bar (swing gui):
	    ProjectManager.getManager().notifySavePropertyChanged(newValue);
	}
                
    }

    /**
     * @return the change flag aka save state
     */
    public boolean hasChanged() {
	return changeFlag;
    }

    /**
     * @see org.tigris.gef.graph.GraphListener#nodeAdded(org.tigris.gef.graph.GraphEvent)
     */
    public void nodeAdded(GraphEvent e) {
	setChangeFlag( true );
    }

    /**
     * @see org.tigris.gef.graph.GraphListener#edgeAdded(org.tigris.gef.graph.GraphEvent)
     */
    public void edgeAdded(GraphEvent e) {
	setChangeFlag( true );
    }

    /**
     * @see org.tigris.gef.graph.GraphListener#nodeRemoved(org.tigris.gef.graph.GraphEvent)
     */
    public void nodeRemoved(GraphEvent e) {
	setChangeFlag( true );
    }

    /**
     * @see org.tigris.gef.graph.GraphListener#edgeRemoved(org.tigris.gef.graph.GraphEvent)
     */
    public void edgeRemoved(GraphEvent e) {
	setChangeFlag( true );
    }

    /**
     * @see org.tigris.gef.graph.GraphListener#graphChanged(org.tigris.gef.graph.GraphEvent)
     */
    public void graphChanged(GraphEvent e) {
	setChangeFlag( true );
    }

} /* end class ChangeRegistry */