RootTreeEditPart.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.gef.editparts;

import org.eclipse.swt.widgets.Tree;
import org.eclipse.swt.widgets.Widget;

import org.eclipse.gef.DragTracker;
import org.eclipse.gef.EditPart;
import org.eclipse.gef.EditPartViewer;
import org.eclipse.gef.Request;
import org.eclipse.gef.RootEditPart;
import org.eclipse.gef.TreeEditPart;
import org.eclipse.gef.commands.Command;
import org.eclipse.gef.commands.UnexecutableCommand;

/**
 * The root editpart for a <code>TreeViewer</code>. There is limited control of a Tree, so
 * this root implementation should work for all purposes.  This implementation does little
 * more than hold onto the viewer, and pass the <code>Tree</code> to the contents as its
 * widget.
 * @author hudsonr
 */
public class RootTreeEditPart
	extends org.eclipse.gef.editparts.AbstractEditPart
	implements RootEditPart, TreeEditPart
{

private EditPartViewer viewer;
private Widget widget;
private TreeEditPart contents;

/**
 * This is where the child gets added. No TreeItem is needed here because
 * the contents is actually represented by the Tree iteself.
 *
 * @param childEditPart  EditPart of child to be added.
 * @param index  Position where it is to be added.
 */
protected void addChildVisual(EditPart childEditPart, int index) {
	((TreeEditPart)childEditPart).setWidget(widget);
}

/**
 * @see org.eclipse.gef.editparts.AbstractEditPart#createEditPolicies()
 */
protected void createEditPolicies() { }

/**
 * @see org.eclipse.gef.EditPart#getCommand(org.eclipse.gef.Request)
 */
public Command getCommand(Request request) {
	return UnexecutableCommand.INSTANCE;
}

/**
 * @see org.eclipse.gef.RootEditPart#getContents()
 */
public EditPart getContents() {
	return contents;
}

/**
 * This method will never be called on a tree root.
 * @see org.eclipse.gef.EditPart#getDragTracker(org.eclipse.gef.Request)
 */
public DragTracker getDragTracker(Request request) {
	return null;
}

/**
 * Returns <code>this</code>.
 * @see org.eclipse.gef.EditPart#getRoot()
 */
public RootEditPart getRoot() {
	return this;
}

/**
 * @see org.eclipse.gef.RootEditPart#getViewer()
 */
public EditPartViewer getViewer() {
	return viewer;
}

/**
 * The editpart holds onto the SWT Tree, which is also the contents' widget.
 * @see org.eclipse.gef.TreeEditPart#getWidget()
 */
public Widget getWidget() {
	return widget;
}

/**
 * Overridden to do nothing since the child is explicitly set.
 * @see org.eclipse.gef.editparts.AbstractEditPart#refreshChildren()
 */
protected void refreshChildren() { }

/**
 * This is where the child gets removed.  This method is overridden
 * here so that the AbstractTreeEditPart does not dispose the widget,
 * which is the Tree in this case.  The tree is owned by the viewer, not the child.
 *
 * @param childEditPart  EditPart of child to be removed.
 */
protected void removeChildVisual(EditPart childEditPart) { 
	((TreeEditPart)childEditPart).setWidget(null);
}

/**
 * @see org.eclipse.gef.RootEditPart#setContents(org.eclipse.gef.EditPart)
 */
public void setContents(EditPart editpart) {
	if (contents != null) {
		if (getWidget() != null)
			((Tree)getWidget()).removeAll();
		removeChild(contents);
	}
	contents = (TreeEditPart)editpart;

	if (contents != null)
		addChild(contents, -1);
}

/**
 * @see org.eclipse.gef.RootEditPart#setViewer(org.eclipse.gef.EditPartViewer)
 */
public void setViewer(EditPartViewer epviewer) {
	viewer = epviewer;
}

/**
 * Called by <code>TreeViewer</code> to set the <code>Tree</code> into the root.  The root
 * simply holds onto this widget and passes it to the contents when the contents is added.
 * @see org.eclipse.gef.TreeEditPart#setWidget(org.eclipse.swt.widgets.Widget)
 */
public void setWidget(Widget w) {
	widget = w;
	if (contents != null)
		contents.setWidget(w);
}

}