VirtualChoice.java

/*
 *  VirtualChoice.java
 *  (FScape)
 *
 *  Copyright (c) 2001-2016 Hanns Holger Rutz. All rights reserved.
 *
 *  This software is published under the GNU General Public License v3+
 *
 *
 *	For further information, please contact Hanns Holger Rutz at
 *	contact@sciss.de
 */

package de.sciss.fscape.gui;

import javax.swing.*;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.util.Vector;

/**
 *  JComboBox subclass that remembers "impossible"
 *	selection, i.e. those with item indices
 *	beyond the current item list which may become
 *	available in the future.
 */
public class VirtualChoice
        extends JComboBox {

// -------- private variables --------

    protected int		virtualIndex;
    protected Vector<ItemListener>	listeners;

// -------- public methods --------

    public VirtualChoice()
    {
        super();
        virtualIndex	= super.getSelectedIndex();
        listeners		= new Vector<ItemListener>();
    }

// XXX
//	public void addItem( String item )
//	{
//		addItem( item );
//	}

    /**
     *	Wenn der virtuelle Index nach dem Add-Vorgang
     *	real als Item existiert, so wird dieses angewaehlt
     */
    public void addItem( String item )
    {
        super.addItem( item );
        if( (getItemCount() - 1) == virtualIndex ) {
            try {
                super.setSelectedIndex( virtualIndex );
            } catch( IllegalArgumentException ignored) {}
        }
    }

    public void insertItemAt( String item, int index )
    throws IllegalArgumentException
    {
        super.insertItemAt( item, index );
        if( (getItemCount() - 1) == virtualIndex ) {
            super.setSelectedIndex( virtualIndex );
        }
    }

    public int getSelectedIndex()
    {
        return virtualIndex;
    }

    /**
     *	defacto wird keine Exception ausgeloest;
     *	falls der Index groesser als die Zahl der Items
     *	ist, wird er intern gespeichert
     *
     *	Eingetragene spezielle ItemListener werden benachrichtigt
     */
    public void setSelectedIndex( int pos )
    throws IllegalArgumentException
    {
        if( pos >= 0 ) {
            virtualIndex = pos;
// System.out.println( "select "+virtualIndex );
            if( getItemCount() > virtualIndex ) {
                super.setSelectedIndex( pos );
            }
        }
        synchronized( listeners ) {
            int size = listeners.size();
            if( size > 0 ) {
                Object[] obj= getSelectedObjects();
                ItemEvent e = new ItemEvent( this, ItemEvent.ITEM_STATE_CHANGED,
                                             ((obj != null) && (obj.length > 0)) ? obj : null,
                                             ItemEvent.SELECTED );
                for( int i = 0; i < size; i++ ) {
                    listeners.elementAt( i ).itemStateChanged( e );
                }
            }
        }
    }

//	public void removeAll()
//	{
//		int pos = virtualIndex;
//		super.removeAll();
//		virtualIndex = pos;
//System.out.println( "removedAll "+virtualIndex );
//	}

//	public void remove( int pos )
//	{
//		int pos2 = virtualIndex;
//		super.remove( pos );
//		virtualIndex = pos2;
//System.out.println( "removed; "+virtualIndex );
//	}

    public void addSpecialItemListener( ItemListener l )
    {
        synchronized( listeners ) {
            listeners.addElement( l );
        }
    }

    public void removeSpecialItemListener( ItemListener l )
    {
        synchronized( listeners ) {
            listeners.removeElement( l );
        }
    }
}