/* XXL: The eXtensible and fleXible Library for data processing

Copyright (C) 2000-2011 Prof. Dr. Bernhard Seeger
                        Head of the Database Research Group
                        Department of Mathematics and Computer Science
                        University of Marburg
                        Germany

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 3 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, see <http://www.gnu.org/licenses/>. 

    http://code.google.com/p/xxl/

*/
package xxl.core.spatial.geometries;

/** A Surface is a two-dimensional geometric object. The OpenGIS Abstract
 *  Specification defines a simple Surface as consisting of a single patch 
 *  that is associated with one exterior boundary and 0 or more interior
 *  boundaries. The boundary of a simple Surface is the set of closed curves
 *  corresponding to its exterior and interior boundaries.  
 *  The only instantiable subclass of Surface defined in the SFS is Polygon,
 *  a simple Surface that is planar.
 *  <br><br>See <a href="./doc-files/ogc_sfs.pdf">Simple Feature Specification (pdf)</a>.
 */
public interface Surface2D extends Geometry2D{

	/** Returns the area of this Surface, as measured in the spatial reference 
	 *  system of this Surface.
	 * @return the area of this Surface
	 */
	public double getArea();
	
	/** Returns the mathematical centroid for this Surface as a Point. The result
	 *  is not guaranteed to be on this Surface.
	 * @return   the mathematical centroid for this Surface as a Point
	 */
	public Point2D getCentroid();
	
	
	/**
	 * Returns a point guaranteed to be on this Surface.
	 * @return  a point guaranteed to be on this Surface
	 */
	public Point2D getInteriorPoint();
}