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+/*
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+ * Copyright (c) 2016 Vivid Solutions.
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+ *
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+ * All rights reserved. This program and the accompanying materials
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+ * are made available under the terms of the Eclipse Public License 2.0
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+ * and Eclipse Distribution License v. 1.0 which accompanies this distribution.
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+ * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v20.html
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+ * and the Eclipse Distribution License is available at
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+ *
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+ * http://www.eclipse.org/org/documents/edl-v10.php.
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+ */
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+
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+package org.locationtech.jts.operation.overlay.snap;
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+
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+import org.locationtech.jts.geom.Geometry;
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+import org.locationtech.jts.operation.overlay.OverlayOp;
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+import org.locationtech.jts.precision.CommonBitsRemover;
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+
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+/**
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+ * Performs an overlay operation using snapping and enhanced precision
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+ * to improve the robustness of the result.
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+ * This class <i>always</i> uses snapping.
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+ * This is less performant than the standard JTS overlay code,
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+ * and may even introduce errors which were not present in the original data.
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+ * For this reason, this class should only be used
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+ * if the standard overlay code fails to produce a correct result.
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+ *
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+ * @author Martin Davis
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+ * @version 1.7
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+ */
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+public class SnapOverlayOp
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+{
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+ public static Geometry overlayOp(Geometry g0, Geometry g1, int opCode)
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+ {
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+ SnapOverlayOp op = new SnapOverlayOp(g0, g1);
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+ return op.getResultGeometry(opCode);
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+ }
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+
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+ public static Geometry intersection(Geometry g0, Geometry g1)
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+ {
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+ if(g0 == null){
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+ return g1;
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+ }
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+ if(g1 == null){
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+ return g0;
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+ }
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+ return overlayOp(g0, g1, OverlayOp.INTERSECTION);
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+ }
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+
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+ public static Geometry union(Geometry g0, Geometry g1)
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+ {
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+ if(g0 == null){
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+ return g1;
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+ }
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+ if(g1 == null){
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+ return g0;
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+ }
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+ return overlayOp(g0, g1, OverlayOp.UNION);
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+ }
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+
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+ public static Geometry difference(Geometry g0, Geometry g1)
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+ {
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+ if(g0 == null){
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+ return g1;
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+ }
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+ if(g1 == null){
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+ return g0;
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+ }
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+ return overlayOp(g0, g1, OverlayOp.DIFFERENCE);
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+ }
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+
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+ public static Geometry symDifference(Geometry g0, Geometry g1)
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+ {
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+ if(g0 == null){
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+ return g1;
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+ }
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+ if(g1 == null){
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+ return g0;
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+ }
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+ return overlayOp(g0, g1, OverlayOp.SYMDIFFERENCE);
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+ }
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+
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+
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+ private Geometry[] geom = new Geometry[2];
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+ private double snapTolerance;
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+
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+ public SnapOverlayOp(Geometry g1, Geometry g2)
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+ {
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+ geom[0] = g1;
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+ geom[1] = g2;
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+ computeSnapTolerance();
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+ }
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+ private void computeSnapTolerance()
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+ {
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+ snapTolerance = GeometrySnapper.computeOverlaySnapTolerance(geom[0], geom[1]);
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+
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+ // System.out.println("Snap tol = " + snapTolerance);
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+ }
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+
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+ public Geometry getResultGeometry(int opCode)
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+ {
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+// Geometry[] selfSnapGeom = new Geometry[] { selfSnap(geom[0]), selfSnap(geom[1])};
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+ Geometry[] prepGeom = snap(geom);
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+ Geometry result = OverlayOp.overlayOp(prepGeom[0], prepGeom[1], opCode);
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+ return prepareResult(result);
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+ }
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+
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+ private Geometry selfSnap(Geometry geom)
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+ {
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+ GeometrySnapper snapper0 = new GeometrySnapper(geom);
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+ Geometry snapGeom = snapper0.snapTo(geom, snapTolerance);
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+ //System.out.println("Self-snapped: " + snapGeom);
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+ //System.out.println();
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+ return snapGeom;
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+ }
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+
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+ private Geometry[] snap(Geometry[] geom)
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+ {
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+ Geometry[] remGeom = removeCommonBits(geom);
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+
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+ // MD - testing only
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+// Geometry[] remGeom = geom;
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+
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+ Geometry[] snapGeom = GeometrySnapper.snap(remGeom[0], remGeom[1], snapTolerance);
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+ // MD - may want to do this at some point, but it adds cycles
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+// checkValid(snapGeom[0]);
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+// checkValid(snapGeom[1]);
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+
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+ /*
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+ System.out.println("Snapped geoms: ");
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+ System.out.println(snapGeom[0]);
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+ System.out.println(snapGeom[1]);
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+ */
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+ return snapGeom;
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+ }
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+
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+ private Geometry prepareResult(Geometry geom)
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+ {
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+ cbr.addCommonBits(geom);
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+ return geom;
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+ }
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+
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+ private CommonBitsRemover cbr;
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+
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+ private Geometry[] removeCommonBits(Geometry[] geom)
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+ {
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+ cbr = new CommonBitsRemover();
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+ cbr.add(geom[0]);
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+ cbr.add(geom[1]);
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+ Geometry remGeom[] = new Geometry[2];
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+ remGeom[0] = cbr.removeCommonBits(geom[0].copy());
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+ remGeom[1] = cbr.removeCommonBits(geom[1].copy());
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+ return remGeom;
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+ }
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+
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+ private void checkValid(Geometry g)
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+ {
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+ if (! g.isValid()) {
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+ System.out.println("Snapped geometry is invalid");
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+ }
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+ }
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+}
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