/*******************************************************************************
 * 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.tools;

import org.eclipse.gef.requests.CreationFactory;

/**
 * A connection creation tool that implements DragTracker. Using this tool,
 * connections are created by clicking on the source edit part, dragging the
 * mouse to the target edit part and releasing the mouse. A
 * {@link org.eclipse.gef.NodeEditPart} might return this drag tracker if the
 * mouse is located over an appropriate anchor.
 */
public class ConnectionDragCreationTool extends AbstractConnectionCreationTool
		implements org.eclipse.gef.DragTracker {

	/**
	 * Default constructor.
	 */
	public ConnectionDragCreationTool() {
	}

	/**
	 * Constructs a new ConnectionDragCreationTool with the given factory.
	 * 
	 * @param factory
	 *            the creation factory
	 */
	public ConnectionDragCreationTool(CreationFactory factory) {
		setFactory(factory);
	}

	/**
	 * Calls super and sets the current state to {@link AbstractTool#STATE_DRAG}
	 * .
	 * 
	 * @see AbstractConnectionCreationTool#handleButtonDown(int)
	 */
	protected boolean handleButtonDown(int button) {
		super.handleButtonDown(button);
		setState(STATE_DRAG);
		return true;
	}

	/**
	 * If the connection has started, the button up event attempts to complete
	 * the connection.
	 * 
	 * @param button
	 *            the button that was released
	 * @return <code>true</code> if this button up event was processed
	 */
	protected boolean handleButtonUp(int button) {
		if (isInState(STATE_CONNECTION_STARTED))
			handleCreateConnection();
		setState(STATE_TERMINAL);
		handleFinished();
		return true;
	}

	/**
	 * When the threshold is passed, transition to CONNECTION_STARTED.
	 * 
	 * @return <code>true</code> if the state transition completed successfully
	 */
	protected boolean handleDragStarted() {
		return stateTransition(STATE_DRAG, STATE_CONNECTION_STARTED);
	}

	/**
	 * Overridden so that nothing happens when this tool is used as a tracker.
	 * If it is the primary tool, then this method behaves normally.
	 * 
	 * @see AbstractTool#handleFinished()
	 */
	protected void handleFinished() {
		if (getDomain().getActiveTool() == this)
			super.handleFinished();
	}

}
