sascha@514: package de.intevation.gnv.math;
sascha@514: 
sascha@514: import com.vividsolutions.jts.geom.Coordinate;
sascha@514: import com.vividsolutions.jts.geom.Envelope;
sascha@514: import com.vividsolutions.jts.geom.Geometry;
sascha@514: import com.vividsolutions.jts.geom.GeometryFactory;
sascha@514: import com.vividsolutions.jts.geom.LinearRing;
sascha@514: import com.vividsolutions.jts.geom.Point;
sascha@514: import com.vividsolutions.jts.geom.Polygon;
sascha@514: 
sascha@514: import com.vividsolutions.jts.index.ItemVisitor;
sascha@514: 
sascha@514: import java.io.Serializable;
sascha@514: 
sascha@514: import java.util.ArrayList;
sascha@514: import java.util.HashMap;
sascha@514: import java.util.List;
sascha@514: 
sascha@517: import org.apache.log4j.Logger;
sascha@517: 
sascha@514: /**
sascha@514:  *  @author Sascha L. Teichmann (sascha.teichmann@intevation.de)
sascha@514:  */
sascha@514: public class GridCell
sascha@514: implements   Serializable
sascha@514: {
sascha@517:     private static Logger log = Logger.getLogger(GridCell.class);
sascha@517: 
sascha@514:     public static final class CellFinder
sascha@514:     implements                ItemVisitor
sascha@514:     {
sascha@514:         public    GridCell found;
sascha@514: 
sascha@514:         protected Point    point;
sascha@514: 
sascha@514:         public CellFinder() {
sascha@514:         }
sascha@514: 
sascha@514:         public void prepare(Coordinate center) {
sascha@514:             found = null;
sascha@514:             point = GEOMETRY_FACTORY.createPoint(center);
sascha@514:         }
sascha@514: 
sascha@514:         public void visitItem(Object item) {
sascha@514:             if (found == null) {
sascha@514:                 GridCell cell = (GridCell)item;
sascha@514:                 if (cell.contains(point)) {
sascha@514:                     found = cell;
sascha@514:                 }
sascha@514:             }
sascha@514:         }
sascha@514:     } // class CellFinder
sascha@514: 
sascha@514:     public Point2d p1;
sascha@514:     public Point2d p2;
sascha@514:     public Point2d p3;
sascha@514:     public Point2d p4;
sascha@514: 
sascha@514:     protected Polygon polygon;
sascha@514: 
sascha@514:     public static final GeometryFactory GEOMETRY_FACTORY
sascha@514:         = new GeometryFactory();
sascha@514: 
sascha@514:     public GridCell() {
sascha@514:     }
sascha@514: 
sascha@514:     public GridCell(Point2d p1, Point2d p2, Point2d p3, Point2d p4) {
sascha@514:         this.p1 = p1;
sascha@514:         this.p2 = p2;
sascha@514:         this.p3 = p3;
sascha@514:         this.p4 = p4;
sascha@514:         createPolygon();
sascha@514:     }
sascha@514: 
sascha@514:     protected void createPolygon() {
sascha@514:         LinearRing shell = GEOMETRY_FACTORY
sascha@514:             .createLinearRing(new Coordinate [] { p1, p2, p3, p4, p1 });
sascha@514:         polygon = GEOMETRY_FACTORY.createPolygon(shell, null);
sascha@514:     }
sascha@514: 
sascha@514:     public Envelope getEnvelope() {
sascha@514:         return polygon.getEnvelopeInternal();
sascha@514:     }
sascha@514: 
sascha@514:     public boolean contains(Geometry coord) {
sascha@514:         return polygon.contains(coord);
sascha@514:     }
sascha@514: 
sascha@514:     public static List<GridCell> pointsToGridCells(
sascha@514:         List<? extends Point2d> points
sascha@514:     ) {
sascha@517:         return pointsToGridCells(points, null);
sascha@517:     }
sascha@517: 
sascha@517:     public static List<GridCell> pointsToGridCells(
sascha@517:         List<? extends Point2d> points,
sascha@517:         Envelope                relevantArea
sascha@517:     ) {
sascha@514:         int minI = Integer.MAX_VALUE;
sascha@514:         int maxI = Integer.MIN_VALUE;
sascha@514:         int minJ = Integer.MAX_VALUE;
sascha@514:         int maxJ = Integer.MIN_VALUE;
sascha@514: 
sascha@514:         HashMap<Integer, HashMap<Integer, Point2d>> rows =
sascha@514:             new HashMap<Integer, HashMap<Integer, Point2d>>();
sascha@514: 
sascha@517:         int culled = 0;
sascha@517: 
sascha@514:         for (Point2d p: points) {
sascha@514: 
sascha@517:             if (relevantArea != null && !relevantArea.contains(p.x, p.y)) {
sascha@517:                 ++culled;
sascha@517:                 continue;
sascha@517:             }
sascha@517: 
sascha@514:             if (p.i < minI) minI = p.i;
sascha@514:             if (p.i > maxI) maxI = p.i;
sascha@514:             if (p.j < minJ) minJ = p.j;
sascha@514:             if (p.j > maxJ) maxJ = p.j;
sascha@514: 
sascha@514:             HashMap<Integer, Point2d> row = rows.get(p.i);
sascha@514: 
sascha@514:             if (row == null) {
sascha@514:                 rows.put(p.i, row = new HashMap<Integer, Point2d>());
sascha@514:             }
sascha@514: 
sascha@514:             row.put(p.j, p);
sascha@514:         }
sascha@514: 
sascha@514:         ArrayList<GridCell> cells = new ArrayList<GridCell>(points.size());
sascha@514: 
sascha@514:         for (int i = minI + 1; i <= maxI; ++i) {
sascha@514:             HashMap<Integer, Point2d> row1 = rows.get(i-1);
sascha@514:             HashMap<Integer, Point2d> row2 = rows.get(i);
sascha@514:             if (row1 != null && row2 != null) {
sascha@514:                 for (int j = minJ + 1; j < maxJ; ++j) {
sascha@514:                     Point2d p1 = row1.get(j-1);
sascha@514:                     Point2d p2 = row1.get(j);
sascha@514:                     Point2d p3 = row2.get(j);
sascha@514:                     Point2d p4 = row2.get(j-1);
sascha@514: 
sascha@514:                     if (p1 != null && p2 != null &&  p3 != null && p4 != null) {
sascha@514:                         cells.add(new GridCell(p1, p2, p3, p4));
sascha@514:                     }
sascha@514:                 } // for all columns in row
sascha@514:             }
sascha@514:         } // for all rows
sascha@514: 
sascha@519:         if (log.isDebugEnabled()) {
sascha@519:             log.debug("culled points: " + culled);
sascha@519:             log.debug("min/max i: " + minI + " / " + maxI);
sascha@519:             log.debug("min/max j: " + minJ + " / " + maxJ);
sascha@519:             log.debug("cells found: " + cells.size());
sascha@519:         }
sascha@519: 
sascha@514:         return cells;
sascha@514:     }
sascha@514: }
sascha@514: // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :