/*
 * Moonlight|3D Copyright (C) 2006 The Moonlight|3D team
 * 
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation; either version 2.1 of the License, or (at your option)
 * any later version.
 * 
 * This library is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
 * details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 * 
 * Created on Feb 10, 2006
 */
package eu.moonlight3d.graph;

import com.trolltech.qt.gui.QGraphicsLineItem;
import com.trolltech.qt.gui.QLineF;


/**
 * A graph model class that represents a link between two slots on two
 * different nodes. Links are directed from the output slot on one node
 * towards the input slot on another node. This is important as it affects
 * the way the graph is laid out by some algorithms.
 *
 * @author gregor
 */
public class Link {
	/**
	 * The output slot to which this link is connected on the input side.
	 */
	private Slot startSlot;
	/**
	 * The input slot to which this link is connected on the output side.
	 */
	private Slot endSlot;
	/**
	 * The Qt GraphicsView item for this link.
	 */
	private QGraphicsLineItem item;

	/**
	 * Default constructor for a link between two slots.
	 * 
	 * @param startSlot the slot from where this link connects
	 * @param endSlot the slot that this link connects to
	 */
	public Link(Slot startSlot, Slot endSlot) {
		this.startSlot=startSlot;
		this.endSlot=endSlot;
	}
	
	/**
	 * Get the slot this link is connected to on the input side
	 * 
	 * @return the slot to which this link is connected
	 */
	public Slot getStartSlot() {
		return startSlot;
	}
	
	/**
	 * Get the slot that this link is connected to on the output side
	 * 
	 * @return the slot to which this link is connected
	 */
	public Slot getEndSlot() {
		return endSlot;
	}

	/**
	 * Internal method to pass a reference to the Qt Graphics View item
	 * that represents this node.
	 * 
	 * @param item the Graphics View item that represents this node 
	 */
	void setItem(QGraphicsLineItem item) {
		this.item=item;
	}
	
	/**
	 * Internal method to get the Qt Graphics View item that represents
	 * this node.
	 * 
	 * @return the Graphics View item that represents the node
	 */
	QGraphicsLineItem getItem() {
		return item;
	}
	
	void setStartPoint(double x, double y) {
		if(item!=null) {
			QLineF line=item.line();
			item.setLine(x, y, line.x2(), line.y2());
		}
	}

	void setEndPoint(double x, double y) {
		if(item!=null) {
			QLineF line=item.line();
			item.setLine(line.x1(), line.y1(), x, y);
		}
	}
}