DeferredContentProvider.java

/*******************************************************************************
 * Copyright (c) 2000, 2005 IBM Corporation and others.
 * 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:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.ui.examples.jobs.views;

import org.eclipse.jface.viewers.AbstractTreeViewer;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.ui.model.BaseWorkbenchContentProvider;
import org.eclipse.ui.progress.DeferredTreeContentManager;

public class DeferredContentProvider extends BaseWorkbenchContentProvider {

	private DeferredTreeContentManager manager;

	@Override
	public void inputChanged(Viewer viewer, Object oldInput, Object newInput) {
		if (viewer instanceof AbstractTreeViewer) {
			manager = new DeferredTreeContentManager(this, (AbstractTreeViewer) viewer);
		}
		super.inputChanged(viewer, oldInput, newInput);
	}

	@Override
	public boolean hasChildren(Object element) {
		// the + box will always appear, but then disappear
		// if not needed after you first click on it.
		if (manager != null) {
			if (manager.isDeferredAdapter(element))
				return manager.mayHaveChildren(element);
		}

		return super.hasChildren(element);
	}

	@Override
	public Object[] getChildren(Object element) {
		if (manager != null) {
			Object[] children = manager.getChildren(element);
			if(children != null) {
				return children;
			}
		}
		return super.getChildren(element);
	}
}