bundles/org.eclipse.gef/src/org/eclipse/gef/handles/ConnectionHandle.java

/*******************************************************************************
 * Copyright (c) 2000, 2010 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.handles;

import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;

import org.eclipse.draw2d.Connection;
import org.eclipse.draw2d.Cursors;

/**
 * The base implementation for handles used with editparts whose figure is a
 * {@link org.eclipse.draw2d.Connection}. This class adds an additional listener
 * to the owner's connection figure to receive notification whenever the owner's
 * connection's points are changed. Changing the points of a connection does not
 * fire "figure moved", it only fires "points" property as changing.
 */
public abstract class ConnectionHandle extends SquareHandle implements
		PropertyChangeListener {

	private boolean fixed = false;

	/**
	 * Creates a new ConnectionHandle.
	 */
	public ConnectionHandle() {
		setCursor(Cursors.CROSS);
	}

	/**
	 * Creates a new handle with the given fixed setting. If the handle is
	 * fixed, it cannot be dragged.
	 * 
	 * @param fixed
	 *            <code>true</code> if the handle cannot be dragged.
	 */
	public ConnectionHandle(boolean fixed) {
		setFixed(fixed);
		if (fixed)
			setCursor(Cursors.NO);
		else
			setCursor(Cursors.CROSS);
	}

	/**
	 * Adds this as a {@link org.eclipse.draw2d.FigureListener} to the owner's
	 * {@link org.eclipse.draw2d.Figure}.
	 */
	public void addNotify() {
		super.addNotify();
		getConnection().addPropertyChangeListener(Connection.PROPERTY_POINTS,
				this);
	}

	/**
	 * Convenience method to return the owner's figure typed as
	 * <code>Connection</code>.
	 * 
	 * @return the owner's connection
	 */
	public Connection getConnection() {
		return (Connection) getOwnerFigure();
	}

	/**
	 * Returns true if the handle cannot be dragged.
	 * 
	 * @return <code>true</code> if the handle cannot be dragged
	 */
	protected boolean isFixed() {
		return fixed;
	}

	/**
	 * @see java.beans.PropertyChangeListener#propertyChange(java.beans.PropertyChangeEvent)
	 */
	public void propertyChange(PropertyChangeEvent evt) {
		if (evt.getPropertyName().equals(Connection.PROPERTY_POINTS))
			revalidate();
	}

	/**
	 * Extended to remove a listener.
	 * 
	 * @see org.eclipse.draw2d.IFigure#removeNotify()
	 */
	public void removeNotify() {
		getConnection().removePropertyChangeListener(
				Connection.PROPERTY_POINTS, this);
		super.removeNotify();
	}

	/**
	 * Sets whether the handle is fixed and cannot be moved
	 * 
	 * @param fixed
	 *            <code>true</code> if the handle should be unmovable
	 */
	public void setFixed(boolean fixed) {
		this.fixed = fixed;
		if (fixed)
			setCursor(Cursors.NO);
		else
			setCursor(Cursors.CROSS);
	}

}