[gef-dev] Proposed additional Anchor for Ellipses

["Alex Selkov" <as@xxxxxxxxxxxxxx>]

package org.eclipse.draw2d;

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

/**
 * @author as
 * 
 * Created 31.08.2002 23:11:43
 */
public class EllipseAnchor extends AbstractConnectionAnchor {

 /**
  * Constructor for EllipseAnchor.
  */
 public EllipseAnchor() {
 }

 /**
  * Constructor for EllipseAnchor.
  * @param owner
  */
 public EllipseAnchor(IFigure owner) {
  super(owner);
 }

 /**
  * @see org.eclipse.draw2d.ConnectionAnchor#getLocation(Point)
  */
 public Point getLocation(Point reference) {

  Rectangle r = Rectangle.SINGLETON;
  r.setBounds(getOwner().getBounds());
  r.translate(-1, -1);
  r.resize(1, 1);
  getOwner().translateToAbsolute(r);

  Point ref = r.getCenter().negate().translate(reference);

  if (ref.x == 0)
   return new Point(reference.x, (ref.y > 0) ? r.bottom() : r.y);
  if (ref.y == 0)
   return new Point((ref.x > 0) ? r.right() : r.x, reference.y);

  float dx = (ref.x > 0) ? 0.5f : -0.5f;
  float dy = (ref.y > 0) ? 0.5f : -0.5f;
  
  // ref.x, ref.y, r.width, r.height != 0 => safe to proceed
  
  float k = (float)(ref.y * r.width) / (ref.x * r.height);
  k = k * k;
  
  return r.getCenter().translate(
    (int) (r.width * dx / Math.sqrt(1 + k)),
    (int) (r.height * dy / Math.sqrt(1 + 1/k)));
 }
}