ContextAction.java

package jav.gui.actions;

import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
import org.openide.util.ContextAwareAction;
import org.openide.util.Lookup;
import org.openide.util.LookupEvent;
import org.openide.util.LookupListener;

/**
 *Copyright (c) 2012, IMPACT working group at the Centrum für Informations- und Sprachverarbeitung, University of Munich.
 *All rights reserved.

 *Redistribution and use in source and binary forms, with or without
 *modification, are permitted provided that the following conditions are met:

 *Redistributions of source code must retain the above copyright
 *notice, this list of conditions and the following disclaimer.
 *Redistributions in binary form must reproduce the above copyright
 *notice, this list of conditions and the following disclaimer in the
 *documentation and/or other materials provided with the distribution.

 *THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 *IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 *TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 *PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 *HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 *LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 *OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 * This file is part of the ocr-postcorrection tool developed
 * by the IMPACT working group at the Centrum für Informations- und Sprachverarbeitung, University of Munich.
 * For further information and contacts visit http://ocr.cis.uni-muenchen.de/
 * 
 * @author thorsten (thorsten.vobl@googlemail.com)
 * 
 * abstract class for creating context sensitive actions
 * the action created listens for a specific class in the lookup provided at
 * creation
 * if said class is found, the action is enabled.
 * if the class is removed from lookup the action is disabled.
 * 
 * 
 */
public abstract class ContextAction<T> extends AbstractAction implements LookupListener, ContextAwareAction {

    private Lookup.Result<T> result = null;

    public ContextAction(Lookup context) {
        init(context);
    }

    private void init(Lookup context) {       
        result = context.lookupResult(contextClass());
        result.addLookupListener(this);
        resultChanged(null);
    }

    @Override
    public void resultChanged(LookupEvent ev) {
        if(!result.allItems().isEmpty()) {
            setEnabled(enable(result.allInstances().iterator().next()));
        } else {
            setEnabled(false);
        }
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        performAction(result.allInstances().iterator().next());
    }

    public abstract Class<T> contextClass();
    public abstract void performAction(T context);
    public abstract boolean enable(T context);
}