| gvSIG desktop 1

/* Spatial Operations & Editing Tools for uDig

 *

 * Axios Engineering under a funding contract with:

 *      Diputación Foral de Gipuzkoa, Ordenación Territorial

 *

 *      http://b5m.gipuzkoa.net

 *      http://www.axios.es

 *

 * (C) 2006, Diputación Foral de Gipuzkoa, Ordenación Territorial (DFG-OT).

 * DFG-OT agrees to licence under Lesser General Public License (LGPL).

 *

 * 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.gvsig.editing.gui.cad.tools.split;

import java.util.ArrayList;

import java.util.List;

import org.slf4j.LoggerFactory;

import com.vividsolutions.jts.geom.Coordinate;

import com.vividsolutions.jts.geom.CoordinateArrays;

import com.vividsolutions.jts.geom.Geometry;

import com.vividsolutions.jts.geom.GeometryFactory;

import com.vividsolutions.jts.geom.LineString;

import com.vividsolutions.jts.geom.Location;

import com.vividsolutions.jts.geom.Point;

import com.vividsolutions.jts.geom.Polygon;

import com.vividsolutions.jts.geomgraph.DirectedEdge;

import com.vividsolutions.jts.geomgraph.Edge;

import com.vividsolutions.jts.geomgraph.Label;

import com.vividsolutions.jts.geomgraph.NodeFactory;

import com.vividsolutions.jts.geomgraph.PlanarGraph;

import com.vividsolutions.jts.geomgraph.Position;

import com.vividsolutions.jts.geomgraph.Quadrant;

/**

 * A {@link PlanarGraph} that builds itself from a {@link Polygon} and a

 * {@link LineString splitting line}.

 * <p>

 * The resulting graph will have the following characteristics:

 * <ul>

 * <li>It will contain as many edges as linestrings in the boundary of the intersection geometry

 * between the polygon and the splitting line string.

 * <li>All edges will be labelled {@link Location#BOUNDARY} at {@link Position#ON}</li>

 * <li>The edges from the polygon's exterior ring will be labelled {@link Location#EXTERIOR} at the

 * {@link Position#LEFT}, {@link Location#INTERIOR} at {@link Position#RIGHT}</li>

 * <li>The edges from the polygon's holes will be labelled {@link Location#INTERIOR} at the

 * {@link Position#LEFT}, {@link Location#EXTERIOR} at {@link Position#RIGHT}</li>

 * </ul>

 * <p>

 * Note the provided polygon may result modified as the result of {@link Polygon#normalize()},

 * which is called in order to ensure propper orientation of the shell and holes.

 * </p>

 * </p>

 *

 * @author Gabriel Roldán, Axios Engineering

 * @author Mauricio Pazos, Axios Engineering

 * @since 1.1.0

 */

class SplitGraph extends PlanarGraph {

    private static final NodeFactory NODE_FACTORY = new SplitGraphNodeFactory();

    private final Polygon            polygon;

    private final LineString         splitter;

    public SplitGraph( Polygon polygon, LineString splitter ) {

        super(NODE_FACTORY);

        this.polygon = polygon;

        // after normalize() we know the shell is oriented CW and the holes CCW

        this.polygon.normalize();

        this.splitter = normalizeSplitter(splitter);

        buildGraph();

    }

    private LineString normalizeSplitter( final LineString original ) {

        // ensure the splitter has no endpoints lying inside the polygon

        LineString splitter = removeInteriorEndPoints(polygon, original);

        // endure the splitter is directed clockwise, as its going

        // to become part of the shell boundary when the tesselation

        // process eliminates other shell edges from the graph

        Coordinate[] splitterCoords = splitter.getCoordinates();

        Coordinate coord0 = splitterCoords[0];

        Coordinate coord1 = splitterCoords[1];

        // determine the orientation of the coordinate sequence given the

        // quadrant of its first vector

        // 1 | 0

        // --+--

        // 2 | 3

        final int quadrant = Quadrant.quadrant(coord0, coord1);

        boolean isCounterClockWise = 1 == quadrant || 2 == quadrant;

        if (isCounterClockWise) {

            CoordinateArrays.reverse(splitterCoords);

            GeometryFactory gf = original.getFactory();

            splitter = gf.createLineString(splitterCoords);

        }

        return splitter;

    }

    /**

     * Removes the given edge and its related {@link DirectedEdge}'s from this graph

     *

     * @param edge the edge to remove

     * @throws IllegalArgumentException if no enclosing DirectedEdge is found for <code>edge</code>

     * @see #remove(DirectedEdge)

     */

    public void remove( final SplitEdge edge ) {

        DirectedEdge edgeEnd = (DirectedEdge) findEdgeEnd(edge);

        if (edgeEnd == null) {

            throw new IllegalArgumentException("No enclosing edge end found for " + edge);

        }

        remove(edgeEnd);

    }

    /**

     * Removes a DirectedEdge, its sym and its {@link SplitEdge} from this graph. May lead to the

     * graph containing dangling nodes.

     *

     * @param edgeEnd

     */

    public void remove( final DirectedEdge edgeEnd ) {

        if (edgeEnd == null) {

            throw new NullPointerException();

        }

        if (edgeEndList.remove(edgeEnd)) {

            DirectedEdge sym = edgeEnd.getSym();

            edgeEndList.remove(sym);

            // shared edge between both ends

            Edge edge = edgeEnd.getEdge();

            edges.remove(edge);

            // node of directed edge end

            SplitGraphNode node = (SplitGraphNode) edgeEnd.getNode();

            // node of symetric directed edge end

            SplitGraphNode endNode = (SplitGraphNode) sym.getNode();

            node.remove(edgeEnd);

            endNode.remove(sym);

        }

    }

    /**

     * Builds a linestrnig from splitter such that it contains no endpoints lying inside the polygon

     *

     * @param polygon

     * @param splitter

     * @return

     */

    private LineString removeInteriorEndPoints( Polygon polygon, LineString splitter ) {

        final Coordinate[] coords = splitter.getCoordinates();

        final GeometryFactory gf = splitter.getFactory();

        int useFrom;

        int useTo;

        for( useFrom = 0; useFrom < coords.length; useFrom++ ) {

            Point p = gf.createPoint(coords[useFrom]);

            if (!polygon.contains(p)) {

                break;

            }

        }

        for( useTo = coords.length - 1; useTo >= useFrom; useTo-- ) {

            Point p = gf.createPoint(coords[useTo]);

            if (!polygon.contains(p)) {

                break;

            }

        }

        if (useFrom == useTo) {

            throw new IllegalArgumentException("Line lies completely inside polygon");

        }

        int length = 1 + (useTo - useFrom);

        Coordinate[] crossingLineCoords = new Coordinate[length];

        System.arraycopy(coords, useFrom, crossingLineCoords, 0, length);

        LineString surelyCrossingLine = gf.createLineString(crossingLineCoords);

        return surelyCrossingLine;

    }

    /**

     * <pre>

     * <code>

     *

     *                  +----------o-----------+

     *                  |          |           |

     *                  |          |           |

     *                  |    +-----------+     |

     *                  |    |     |     |     |

     *                  |    |     |     |     |

     *                  |    |     |     |     |

     *                  |    o__\__o_____|     |

     *                  |       /  |           |

     *                 /|\        /|\          |

     *                  o__________o___________|

     *

     *

     * </code>

     * </pre>

     *

     * @throws Exception

     */

    private void buildGraph() {

        Geometry intersectingLineStrings = polygon.intersection(splitter);

        Geometry nodedShell = polygon.getExteriorRing().difference(splitter);

        LineString[] interiorRings = new LineString[polygon.getNumInteriorRing()];

        for( int i = 0; i < polygon.getNumInteriorRing(); i++ ) {

            LineString interiorRingN = polygon.getInteriorRingN(i);

            interiorRings[i] = interiorRingN;

        }

        GeometryFactory factory = polygon.getFactory();

        Geometry interiorRingCollection = factory.createMultiLineString(interiorRings);

        Geometry nodedHoles = interiorRingCollection.difference(splitter);

        // shell segments oriented CW means exterior at the left, interior at

        // the right

        addEdges(nodedShell, Location.BOUNDARY, Location.EXTERIOR, Location.INTERIOR);

        // hole segments oriented CCW means interior at the left, exterior at

        // the right

        addEdges(nodedHoles, Location.BOUNDARY, Location.INTERIOR, Location.EXTERIOR);

        // splitter intersection segments have interior location at both left

        // and right

        addEdges(intersectingLineStrings, Location.BOUNDARY, Location.INTERIOR, Location.INTERIOR);

    }

    private void addEdges( Geometry linearGeom, int onLoc, int leftLoc, int rightLoc ) {

        final int nParts = linearGeom.getNumGeometries();

        Geometry currGeom;

        Coordinate[] coords;

        List edges = new ArrayList();

        for( int i = 0; i < nParts; i++ ) {

            currGeom = linearGeom.getGeometryN(i);

            coords = currGeom.getCoordinates();

            if (coords.length<2)

                    continue;

            Label label = new Label(onLoc, leftLoc, rightLoc);

            Edge edge = new SplitEdge(coords, label);

            edges.add(edge);

        }

        // for each edge in the list, adds two DirectedEdge, one reflecting

        // the given edge and other the opposite

        try{

                super.addEdges(edges);

        }catch (Exception e) {

                        LoggerFactory.getLogger(this.getClass()).error(e.getLocalizedMessage(),e);

                }

    }

}