pathtype.java

GEo 地理操作源代码

/**************************************************************************************************
 **
 ** $Id: PathType.java,v 1.5 2004/05/06 22:05:52 desruisseaux Exp $
 **
 ** $Source: /cvsroot/geoapi/src/org/opengis/go/spatial/PathType.java,v $
 **
 ** Copyright (C) 2003 Open GIS Consortium, Inc. All Rights Reserved. http://www.opengis.org/Legal/
 **
 *************************************************************************************************/
package org.opengis.go.spatial;

// J2SE direct dependencies
import java.util.ArrayList;
import java.util.List;

import org.opengis.util.CodeList;
import org.opengis.util.SimpleEnumerationType;

/**
 * <p>
 * This class serves as the base class for objects that represent the
 * various methods for computing a path between two locations.
 * Singleton instances of PathType will exist to represent for example
 * a path of constant bearing (rhumbline), or a great circle path.
 * <p>
 * Path type is an algorithmic sequence of interpolation and projection.
 * <ul>
 * <li>For <b>rhumbline</b>, <b>great circle</b>, and <b>vector</b>, first
 * <i>interpolation</i> is done on the verteces, which gives in-between points.
 * These in-between points are then <i>projected</i> into the display space, 
 * which converts them to display points.</li>
 * <li>For <b>pixel-straight</b> and <b>spline</b>, the verteces are first <i>projected</i>
 * into the display space as display points. These display points are <i>interpolated</i>,
 * which generates in-between display points.</li>
 * </ul>
 * For each path type, an implementations will iteratively apply the respective algorithms
 * until the appropriate display resolution is reached.
 * <p>
 * <center>
 * <table border=1>
 * <b> <tr><td>Path Type</td> <td>Interpolation Method</td> </tr></b>
 * <tr><td>rhumbline</td> <td>constant bearing</td></tr>
 * <tr><td>great circle</td> <td>geodesic</td></tr>
 * <tr><td>vector</td> <td>linear in worldspace (interpolation before projection)</td></tr>
 * <tr><td>pixel-straight</td> <td>linear in display space (interpolation after projection)</td></tr>
 * <tr><td>spline</td> <td>cubic in display space (interpolation after projection)</td></tr>
 * </table>
 * </center>
 * <p>
 * @author Open GIS Consortium, Inc.
 * @version $Revision: 1.5 $, $Date: 2004/05/06 22:05:52 $
 */
public class PathType extends SimpleEnumerationType {

    /**
     * The list of enumeration available in this virtual machine.
     * <strong>Must be declared first!</strong>.
     */
    protected static final List VALUES = new ArrayList();   
     
    /**
     * Creates a new PathType with the given value and name.
     * @param name the short name for the enum.
     * @param description the description for the enum.
     */
    protected PathType(String name, String description) {
        super(VALUES, name, description);               
    }
        
    /**
     * Returns the list of <code>PathType</code>s.
     */
    public static PathType[] values() {
        synchronized (VALUES) {
            return (PathType[]) VALUES.toArray(new PathType[VALUES.size()]);
        }
    }

    /**
     * Returns the list of enumerations of the same kind than this enum.
     */
    public CodeList[] family() {
        return values();
    }   
}