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The main module contains the GeoTools public interfaces that are used by other GeoTools modules (and GeoTools applications). Where possible we make use industry standard terms as provided by OGC and ISO standards. The formal GeoTools public api consists of gt-metadata, jts and the gt-main module. The main module contains the default implementations that are available provided to other GeoTools modules using our factory system. Factories are obtained from an appropriate FactoryFinder, giving applications a chance configure the factory used using the Factory Hints facilities. FilterFactory ff = CommonFactoryFinder.getFilterFactory(); Expression expr = ff.add( expression1, expression2 ); If you find yourself using implementation specific classes chances are you doing it wrong: Expression expr = new AddImpl( expression1, expressiom2 );

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/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 *
 *    (C) 2014, 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.jts;

import java.util.List;
import java.util.concurrent.atomic.AtomicBoolean;
import org.locationtech.jts.geom.Coordinate;
import org.locationtech.jts.geom.CoordinateSequence;
import org.locationtech.jts.geom.Geometry;
import org.locationtech.jts.geom.GeometryComponentFilter;
import org.locationtech.jts.geom.GeometryFactory;
import org.locationtech.jts.geom.LineString;

/**
 * Utility methods for curved geometries
 *
 * @author Andrea Aime - GeoSolutions
 */
public class CurvedGeometries {

    /** Returns true if the geometry is curved, or contains elements that are curved */
    public static boolean isCurved(Geometry geometry) {
        if (geometry instanceof CurvedGeometry) {
            return true;
        }

        final AtomicBoolean curveFound = new AtomicBoolean(false);
        geometry.apply(
                new GeometryComponentFilter() {

                    @Override
                    public void filter(Geometry geom) {
                        if (geom instanceof CurvedGeometry) {
                            curveFound.set(true);
                        }
                    }
                });

        return curveFound.get();
    }

    /** Checks if the specified geometry is a circle */
    public static boolean isCircle(Geometry geom) {
        if (geom.isEmpty()) {
            return false;
        }
        if (!(geom instanceof CircularRing) && !(geom instanceof CompoundRing)) {
            return false;
        }
        if (geom instanceof CircularRing) {
            // check that all arcs have the same center and radius
            CircularRing curved = (CircularRing) geom;
            CircularArc first = curved.getArcN(0);
            double radius = first.getRadius();
            if (radius == Double.POSITIVE_INFINITY) {
                return false;
            }
            Coordinate center = first.getCenter();
            final int numArcs = curved.getNumArcs();
            for (int i = 1; i < numArcs; i++) {
                CircularArc curr = curved.getArcN(i);
                if (!CircularArc.equals(curr.getRadius(), radius)) {
                    return false;
                }
                Coordinate cc = curr.getCenter();
                if (!CircularArc.equals(cc.x, center.x) || !CircularArc.equals(cc.y, center.y)) {
                    return false;
                }
            }

            return true;
        } else {
            // check that all arcs in the components have the same center and radius, and that
            // all components are curved
            CompoundRing curved = (CompoundRing) geom;
            List components = curved.getComponents();
            double radius = Double.NaN;
            Coordinate center = null;
            for (LineString component : components) {
                if (!(component instanceof SingleCurvedGeometry)) {
                    return false;
                }
                SingleCurvedGeometry curvedComponent = (SingleCurvedGeometry) component;
                final int numArcs = curvedComponent.getNumArcs();
                for (int i = 0; i < numArcs; i++) {
                    CircularArc curr = curvedComponent.getArcN(i);
                    if (center == null) {
                        radius = curr.getRadius();
                        if (radius == Double.POSITIVE_INFINITY) {
                            return false;
                        }
                        center = curr.getCenter();
                    } else {
                        if (!CircularArc.equals(curr.getRadius(), radius)) {
                            return false;
                        }
                        Coordinate cc = curr.getCenter();
                        if (!CircularArc.equals(cc.x, center.x)
                                || !CircularArc.equals(cc.y, center.y)) {
                            return false;
                        }
                    }
                }
            }

            return true;
        }
    }

    /** Builds a circular arc out of the specified coordinate sequence */
    public static CircularArc getArc(CoordinateSequence cs, int startCoordinate) {
        if (cs.size() < (startCoordinate + 3)) {
            throw new IllegalArgumentException(
                    "The coordinate sequence has "
                            + cs.size()
                            + " points, cannot extract a circular arc starting from coordinate "
                            + startCoordinate);
        } else if (startCoordinate < 0) {
            throw new IllegalArgumentException(
                    "Start coordinate must be 0 or positive, not: " + startCoordinate);
        }

        return new CircularArc(
                cs.getOrdinate(0, 0),
                cs.getOrdinate(0, 1), //
                cs.getOrdinate(1, 0),
                cs.getOrdinate(1, 1), //
                cs.getOrdinate(2, 0),
                cs.getOrdinate(2, 1));
    }

    /** Returns the circle containing this arc */
    public static CircularRing toCircle(
            CircularArc arc, GeometryFactory geometryFactory, double tolerance) {
        double radius = arc.getRadius();
        Coordinate center = arc.getCenter();

        double[] rcp = new double[10];
        rcp[0] = center.x + radius;
        rcp[1] = center.y;
        rcp[2] = center.x;
        rcp[3] = center.y + radius;
        rcp[4] = center.x - radius;
        rcp[5] = center.y;
        rcp[6] = center.x;
        rcp[7] = center.y - radius;
        rcp[8] = center.x + radius;
        rcp[9] = center.y;

        return new CircularRing(rcp, geometryFactory, tolerance);
    }

    /**
     * Extracts a {@link CurvedGeometryFactory} from the provided geometry, either by just returning
     * the one that is held by the geometry, if consistent with its tolerance, or by creating a new
     * one
     */
    public static CurvedGeometryFactory getFactory(CurvedGeometry curved) {
        GeometryFactory factory = ((Geometry) curved).getFactory();
        if (factory instanceof CurvedGeometryFactory) {
            CurvedGeometryFactory cf = (CurvedGeometryFactory) factory;
            if (cf.getTolerance() == curved.getTolerance()) {
                return cf;
            }
        }
        return new CurvedGeometryFactory(factory, curved.getTolerance());
    }
}