/*******************************************************************************
 * 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.draw2d;

import org.eclipse.draw2d.geometry.Point;
import org.eclipse.draw2d.geometry.Rectangle;

/**
 * The ChopboxAnchor's location is found by calculating the intersection of a line drawn
 * from the center point of its owner's box to a reference point on that box. Thus 
 * {@link Connection Connections} using the ChopBoxAnchor will be oriented such that they
 * point to their owner's center.
 */
public class ChopboxAnchor
	extends AbstractConnectionAnchor
{

/**
 * Constructs a new ChopboxAnchor.
 */
protected ChopboxAnchor() { }

/**
 * Constructs a ChopboxAnchor with the given <i>owner</i> figure.
 * 
 * @param owner The owner figure
 * @since 2.0
 */
public ChopboxAnchor(IFigure owner) {
	super(owner);
}

/**
 * Gets a Rectangle from {@link #getBox()} and returns the Point where a line from the
 * center of the Rectangle to the Point <i>reference</i> intersects the Rectangle.
 * 
 * @param reference The reference point
 * @return The anchor location
 */
public Point getLocation(Point reference) {
	Rectangle r = Rectangle.SINGLETON;
	r.setBounds(getBox());
	r.translate(-1, -1);
	r.resize(1, 1);

	getOwner().translateToAbsolute(r);
	float centerX = r.x + 0.5f * r.width;
	float centerY = r.y + 0.5f * r.height;
	
	if (r.isEmpty() || (reference.x == (int)centerX && reference.y == (int)centerY))
		return new Point((int)centerX, (int)centerY);  //This avoids divide-by-zero

	float dx = reference.x - centerX;
	float dy = reference.y - centerY;
	
	//r.width, r.height, dx, and dy are guaranteed to be non-zero. 
	float scale = 0.5f / Math.max(Math.abs(dx) / r.width, Math.abs(dy) / r.height);

	dx *= scale;
	dy *= scale;
	centerX += dx;
	centerY += dy;

	return new Point(Math.round(centerX), Math.round(centerY));
}

/**
 * Returns the bounds of this ChopboxAnchor's owner.  Subclasses can override this method
 * to adjust the box the anchor can be placed on.  For instance, the owner figure may have
 * a drop shadow that should not be included in the box. 
 *  
 * @return The bounds of this ChopboxAnchor's owner
 * @since 2.0
 */
protected Rectangle getBox() {
	return getOwner().getBounds();
}

/**
 * Returns the anchor's reference point. In the case of the ChopboxAnchor, this is the
 * center of the anchor's owner.
 * 
 * @return The reference point
 */
public Point getReferencePoint() {
	Point ref = getBox().getCenter();
	getOwner().translateToAbsolute(ref);
	return ref;
}


/**
 * Returns <code>true</code> if the other anchor has the same owner and box.
 * @param obj the other anchor
 * @return <code>true</code> if equal
 */
public boolean equals(Object obj) {
	if (obj instanceof ChopboxAnchor) {
		ChopboxAnchor other = (ChopboxAnchor)obj;
		return other.getOwner() == getOwner() && other.getBox().equals(getBox());
	}
	return false;
}

/**
 * The owning figure's hashcode is used since equality is approximately based on the
 * owner.
 * @return the hash code.
 */
public int hashCode() {
	if (getOwner() != null)
		return getOwner().hashCode();
	else
		return super.hashCode();
}

}