TreeDataNodeContentProvider.java

/*******************************************************************************
 * Copyright (c) 2008
 * The code, documentation and other materials contained herein have been
 * licensed under the Eclipse Public License - v 1.0 by the individual
 * copyright holders listed below, as Initial Contributors under such license.
 * The text of such license is available at 
 * http://www.eclipse.org/legal/epl-v10.html.
 * 
 * Contributors:
 * 		Henrik Lindberg
 *******************************************************************************/

package org.eclipse.buckminster.generic.ui.providers;

import org.eclipse.buckminster.generic.model.tree.ITreeDataListener;
import org.eclipse.buckminster.generic.model.tree.ITreeDataNode;
import org.eclipse.buckminster.generic.model.tree.ITreeParentDataNode;
import org.eclipse.buckminster.generic.model.tree.ITreeRootNode;
import org.eclipse.buckminster.generic.model.tree.TreeDataEvent;
import org.eclipse.buckminster.generic.ui.Messages;
import org.eclipse.jface.viewers.IStructuredContentProvider;
import org.eclipse.jface.viewers.ITreeContentProvider;
import org.eclipse.jface.viewers.TreeViewer;
import org.eclipse.jface.viewers.Viewer;

/**
 * The TreeDataNodeContentProvider uses an ITreeRootNode to hold the tree's
 * data.
 * 
 * This content provider registers itself as a listener to change in the
 * ITreeRootNode and refreshes the view when events occur. A UI safe
 * implementation of ITreeRootNode must be used.
 * 
 * @author Henrik Lindberg
 * 
 */
public abstract class TreeDataNodeContentProvider implements IStructuredContentProvider, ITreeContentProvider, ITreeDataListener {
	private ITreeRootNode invisibleRoot;

	private TreeViewer treeViewer;

	@Override
	public void dispose() {
		invisibleRoot.removeTreeDataListener(this);
	}

	@Override
	public Object[] getChildren(Object parent) {
		if (parent instanceof ITreeParentDataNode) {
			return ((ITreeParentDataNode) parent).getChildren();
		}
		return new Object[0];
	}

	@Override
	public Object[] getElements(Object parent) {
		// if asking for the data that was used to build a tree, then return the
		// root holding the tree.
		// the previous version used the ViewSite as this outermost parent
		// but that only works for a content provider where the tree always
		// shows the same content
		//
		if (!(parent instanceof ITreeDataNode)) // Was (parent instanceof
												// IViewSite)
		{
			if (invisibleRoot == null)
				initialize();
			return getChildren(invisibleRoot);
		}
		return getChildren(parent);
	}

	@Override
	public Object getParent(Object child) {
		if (child instanceof ITreeDataNode) {
			return ((ITreeDataNode) child).getParent();
		}
		return null;
	}

	@Override
	public boolean hasChildren(Object parent) {
		if (parent instanceof ITreeParentDataNode)
			return ((ITreeParentDataNode) parent).hasChildren();
		return false;
	}

	@Override
	public void inputChanged(Viewer v, Object oldInput, Object newInput) {
		if (!(v instanceof TreeViewer))
			throw new IllegalArgumentException(Messages.only_TreeView_accepted);
		treeViewer = (TreeViewer) v;
	}

	@Override
	public void treeNodeChanged(TreeDataEvent event) {
		switch (event.getType()) {
			case CHANGE:
				// if the changed node is the root node - refresh the entire
				// tree
				if (event.getNode() instanceof ITreeRootNode)
					treeViewer.refresh();
				else
					treeViewer.refresh(event.getNode());
				break;
		}
	}

	protected ITreeParentDataNode getHiddenRoot() {
		return invisibleRoot;
	}

	/*
	 * Initialize the hidden root. Should call setHiddenRoot() with the root to
	 * use.
	 */
	protected abstract void initialize();

	protected void setHiddenRoot(ITreeRootNode hiddenRoot) {
		if (invisibleRoot != null)
			invisibleRoot.removeTreeDataListener(this);
		invisibleRoot = hiddenRoot;
		invisibleRoot.addTreeDataListener(this);
	}
}