FeedbackHelper.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.editpolicies;

import org.eclipse.draw2d.Connection;
import org.eclipse.draw2d.ConnectionAnchor;
import org.eclipse.draw2d.XYAnchor;
import org.eclipse.draw2d.geometry.Point;

/**
 * Helps display connection feedback during drags of the connection ends. This class is
 * used internally by the provided EditPolicy implementation.
 * @author hudsonr
 */
public class FeedbackHelper {

private Connection connection;
private XYAnchor dummyAnchor;
private boolean isMovingStartAnchor = false;

/**
 * Constructs a new FeedbackHelper.
 */
public FeedbackHelper() {
	dummyAnchor = new XYAnchor(new Point(10, 10));
}

/**
 * Returns the connection being used to show feedback.
 * @return the connection
 */
protected Connection getConnection() {
	return connection;
}

/**
 * Returns true is the feedback is moving the source anchor
 * @return <code>true</code> if moving start
 */
protected boolean isMovingStartAnchor() {
	return isMovingStartAnchor;
}

/**
 * Sets the connection.
 * @param c connection
 */
public void setConnection(Connection c) {
	connection = c;
}

/**
 * Sets if moving start of connection.
 * @param value <code>true</code> if the starts is being moved
 */
public void setMovingStartAnchor(boolean value) {
	isMovingStartAnchor = value;
}

/**
 * Sets the anchor for the end being moved.
 * @param anchor the new anchor
 */
protected void setAnchor(ConnectionAnchor anchor) {
	if (isMovingStartAnchor()) 
		getConnection().setSourceAnchor(anchor);
	else
		getConnection().setTargetAnchor(anchor);
}

/**
 * Updates the feedback based on the given anchor or point.  The anchor is used unless
 * <code>null</code>.  The point is used when there is no anchor.
 * @param anchor <code>null</code> or an anchor
 * @param p the point to use when there is no anchor
 */
public void update(ConnectionAnchor anchor, Point p) {
	if (anchor != null)
		setAnchor(anchor);
	else {
		dummyAnchor.setLocation(p);
		setAnchor(dummyAnchor);
	}
}

}