/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2001-2006 Vivid Solutions
* (C) 2001-2008, Open Source Geospatial Foundation (OSGeo)
*
* 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;
* version 2.1 of the License.
*
* 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.
*/
package org.geotools.geometry.iso.operation.overlay;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.geotools.geometry.iso.coordinate.DirectPositionImpl;
import org.geotools.geometry.iso.primitive.PointImpl;
import org.geotools.geometry.iso.topograph2D.Coordinate;
import org.geotools.geometry.iso.topograph2D.Label;
import org.geotools.geometry.iso.topograph2D.Node;
import org.geotools.geometry.iso.util.algorithm2D.PointLocator;
import org.opengis.referencing.crs.CoordinateReferenceSystem;
// import java.util.*;
// import com.vividsolutions.jts.geom.*;
// import com.vividsolutions.jts.algorithm.*;
// import com.vividsolutions.jts.geomgraph.*;
/**
* Constructs {@link org.opengis.geometry.primitive.Point}s from the nodes of an overlay graph.
*
*
*
*
*
* @source $URL$
* @version 1.7.2
*/
public class PointBuilder {
private OverlayOp op;
//private FeatGeomFactoryImpl featGeomFactory;
private CoordinateReferenceSystem crs;
//private PrimitiveFactoryImpl primitiveFactory;
private List resultPointList = new ArrayList();
public PointBuilder(OverlayOp op, CoordinateReferenceSystem crs,
PointLocator ptLocator) {
this.op = op;
this.crs = crs;
//this.primitiveFactory = featGeomFactory.getPrimitiveFactory();
// ptLocator is never used in this class
}
/**
* Computes the Point geometries which will appear in the result, given the
* specified overlay operation.
*
* @return a list of the Points objects in the result
*/
public List build(int opCode) {
extractNonCoveredResultNodes(opCode);
/**
* It can happen that connected result nodes are still covered by result
* geometries, so must perform this filter. (For instance, this can
* happen during topology collapse).
*/
return resultPointList;
}
/**
* Determines nodes which are in the result, and creates {@link Point}s for
* them.
*
* This method determines nodes which are candidates for the result via
* their labelling and their graph topology.
*
* @param opCode
* the overlay operation
*/
private void extractNonCoveredResultNodes(int opCode) {
// testing only
// if (true) return resultNodeList;
for (Iterator nodeit = op.getGraph().getNodes().iterator(); nodeit
.hasNext();) {
Node n = (Node) nodeit.next();
// filter out nodes which are known to be in the result
if (n.isInResult())
continue;
// if an incident edge is in the result, then the node coordinate is
// included already
if (n.isIncidentEdgeInResult())
continue;
if (n.getEdges().getDegree() == 0
|| opCode == OverlayOp.INTERSECTION) {
/**
* For nodes on edges, only INTERSECTION can result in edge
* nodes being included even if none of their incident edges are
* included
*/
Label label = n.getLabel();
if (OverlayOp.isResultOfOp(label, opCode)) {
filterCoveredNodeToPoint(n);
}
}
}
// System.out.println("connectedResultNodes collected = " +
// connectedResultNodes.size());
}
/**
* Converts non-covered nodes to Point objects and adds them to the result.
*
* A node is covered if it is contained in another element Geometry with
* higher dimension (e.g. a node point might be contained in a polygon, in
* which case the point can be eliminated from the result).
*
* @param n
* the node to test
*/
private void filterCoveredNodeToPoint(Node n) {
Coordinate coord = n.getCoordinate();
if (!op.isCoveredByLA(coord)) {
PointImpl pt = new PointImpl(new DirectPositionImpl(crs, coord.getCoordinates()));
//PointImpl pt = primitiveFactory.createPoint(coord.getCoordinates());
resultPointList.add(pt);
}
}
}