TextViewerBlock.java

/*******************************************************************************
 * Copyright (c) 2012 xored software, Inc.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 *     xored software, Inc. - initial API and implementation (Yuri Strot)
 ******************************************************************************/
package com.xored.glance.internal.ui.viewers;

import java.lang.reflect.Field;
import java.util.List;

import org.eclipse.core.runtime.ListenerList;
import org.eclipse.jface.text.ITextListener;
import org.eclipse.jface.text.TextEvent;
import org.eclipse.jface.text.TextViewer;

import com.xored.glance.ui.sources.ITextBlock;
import com.xored.glance.ui.sources.ITextBlockListener;
import com.xored.glance.ui.sources.TextChangedEvent;

/**
 * @author Yuri Strot
 * 
 */
public class TextViewerBlock implements ITextBlock, ITextListener {

    public TextViewerBlock(TextViewer viewer) {
        this.viewer = viewer;
        listeners = new ListenerList();
        addListeners();
    }

    public void dispose() {
        removeListeners();
    }

    protected void addListeners() {
        if (!addFirstListener()) {
            viewer.addTextListener(this);
        }
    }

    /**
     * Add our text listener to the beginning of the listener list thro
     * reflection. This method return true if this operation succeed and fail
     * otherwise.
     */
    private boolean addFirstListener() {
        try {
            Field filed = TextViewer.class.getDeclaredField("fTextListeners");
            filed.setAccessible(true);
            @SuppressWarnings("unchecked")
            List<Object> list = (List<Object>) filed.get(viewer);
            if (list == null) {
                // no listeners, can add it usual way
                return false;
            }
            if (!list.contains(this)) {
                list.add(0, this);
            }
            return true;
        } catch (Exception e) {
            return false;
        }
    }

    protected void removeListeners() {
        viewer.removeTextListener(this);
    }

    public void textChanged(TextEvent event) {
        if (event.getDocumentEvent() != null) {
            TextChangedEvent changedEvent = new TextChangedEvent(event.getOffset(), event.getLength(),
                event.getReplacedText());
            fireTextChanged(changedEvent);
        }
    }

    protected void fireTextChanged(TextChangedEvent changedEvent) {
        Object[] objects = listeners.getListeners();
        for (Object object : objects) {
            ITextBlockListener listener = (ITextBlockListener) object;
            listener.textChanged(changedEvent);
        }
    }

    public void addTextBlockListener(ITextBlockListener listener) {
        listeners.add(listener);
    }

    public String getText() {
        return viewer.getDocument().get();
    }

    public void removeTextBlockListener(ITextBlockListener listener) {
        listeners.remove(listener);
    }

    public int compareTo(ITextBlock o) {
        return 0;
    }

    private ListenerList listeners;
    protected TextViewer viewer;

}