de.quamoco.qm.editor.util.LabelDecoratorBase.java Source code

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Here is the source code for de.quamoco.qm.editor.util.LabelDecoratorBase.java

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/*-------------------------------------------------------------------------+
|                                                                          |
| Copyright 2012 Technische Universitaet Muenchen and                      |
| Fraunhofer-Institut fuer Experimentelles Software Engineering (IESE)     |
|                                                                          |
| 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 de.quamoco.qm.editor.util;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.jface.viewers.ILabelDecorator;
import org.eclipse.jface.viewers.ILabelProviderListener;
import org.eclipse.jface.viewers.LabelProviderChangedEvent;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.widgets.Display;

/**
 * Base class for {@link ILabelDecorator} that provides implementation for
 * registering and notifying listeners.
 * 
 * @author herrmama
 * @author $Author: lochmann $
 * @version $Rev: 4974 $
 * @levd.rating YELLOW Hash: 958D4F47DBBDB2D8A7B3B5B45738ACEC
 */
public abstract class LabelDecoratorBase implements ILabelDecorator {

    /** The listeners that listen to this decorator. */
    private List<ILabelProviderListener> listeners;

    /** {@inheritDoc} */
    @Override
    public void addListener(ILabelProviderListener listener) {
        if (listeners == null) {
            listeners = new ArrayList<ILabelProviderListener>();
            firstListenerAdded();
        }
        listeners.add(listener);
    }

    /**
     * Template method to notify that the first listener has been added to the
     * decorator.
     */
    protected void firstListenerAdded() {
        // to be overwritten by subclasses
    }

    /** {@inheritDoc} */
    @Override
    public void removeListener(ILabelProviderListener listener) {
        listeners.remove(listener);
        if (listeners.isEmpty()) {
            listeners = null;
            lastListenerRemoved();
        }
    }

    /**
     * Template method to notify that the last listener has been removed from
     * the decorator.
     */
    protected void lastListenerRemoved() {
        // to be overwritten by subclasses
    }

    /** Notify the listeners about changes to certain elements. */
    protected void notifyListeners(Object[] elements) {
        if (listeners == null) {
            return;
        }
        if (elements == null || elements.length == 0) {
            return;
        }
        Display display = Display.getDefault();
        if (display == null || display.isDisposed()) {
            return;
        }
        final LabelProviderChangedEvent event = new LabelProviderChangedEvent(this, elements);
        for (final ILabelProviderListener listener : listeners) {
            display.asyncExec(new Runnable() {
                @Override
                public void run() {
                    listener.labelProviderChanged(event);
                }
            });
        }
    }

    /** {@inheritDoc} */
    @Override
    public Image decorateImage(Image image, Object element) {
        // default implementation so that sub classes do not need to overwrite
        return null;
    }

    /** {@inheritDoc} */
    @Override
    public String decorateText(String text, Object element) {
        // default implementation so that sub classes do not need to overwrite
        return null;
    }

    /** {@inheritDoc} */
    @Override
    public void dispose() {
        // default implementation so that sub classes do not need to overwrite
    }

    /** {@inheritDoc} */
    @Override
    public boolean isLabelProperty(Object element, String property) {
        // default implementation so that sub classes do not need to overwrite
        return false;
    }
}