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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) 2004-2008, 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.jts;

import java.awt.geom.AffineTransform;
import org.locationtech.jts.geom.Coordinate;
import org.locationtech.jts.geom.CoordinateSequence;
import org.locationtech.jts.geom.LineString;
import org.locationtech.jts.geom.Polygon;

/**
 * A path iterator for the LiteShape class, specialized to iterate over Polygon objects.
 *
 * @author Andrea Aime
 * @author simone giannecchini
 * @version $Id$
 */
public final class PolygonIterator extends AbstractLiteIterator {
    /** Transform applied on the coordinates during iteration */
    private AffineTransform at;

    /** The rings describing the polygon geometry */
    private LineString[] rings;

    /** The current ring during iteration */
    private int currentRing = 0;

    /** Current line coordinate */
    private int currentCoord = 0;

    /** The array of coordinates that represents the line geometry */
    private CoordinateSequence coords = null;

    /** The previous coordinate (during iteration) */
    private Coordinate oldCoord = null;

    /** True when the iteration is terminated */
    private boolean done = false;

    /** If true, apply simple distance based generalization */
    private boolean generalize = false;

    /** Maximum distance for point elision when generalizing */
    private double maxDistance = 1.0;

    /** Horizontal scale, got from the affine transform and cached */
    private double xScale;

    /** Vertical scale, got from the affine transform and cached */
    private double yScale;

    /**
     * Creates a new PolygonIterator object.
     *
     * @param p The polygon
     * @param at The affine transform applied to coordinates during iteration
     */
    public PolygonIterator(Polygon p, AffineTransform at) {
        int numInteriorRings = p.getNumInteriorRing();
        rings = new LineString[numInteriorRings + 1];
        rings[0] = p.getExteriorRing();

        for (int i = 0; i < numInteriorRings; i++) {
            rings[i + 1] = p.getInteriorRingN(i);
        }

        if (at == null) {
            at = new AffineTransform();
        }

        this.at = at;
        xScale = Math.sqrt((at.getScaleX() * at.getScaleX()) + (at.getShearX() * at.getShearX()));
        yScale = Math.sqrt((at.getScaleY() * at.getScaleY()) + (at.getShearY() * at.getShearY()));

        coords = rings[0].getCoordinateSequence();
    }

    /**
     * Creates a new PolygonIterator object.
     *
     * @param p The polygon
     * @param at The affine transform applied to coordinates during iteration
     * @param generalize if true apply simple distance based generalization
     */
    public PolygonIterator(Polygon p, AffineTransform at, boolean generalize) {
        this(p, at);
        this.generalize = generalize;
    }

    /**
     * Creates a new PolygonIterator object.
     *
     * @param p The polygon
     * @param at The affine transform applied to coordinates during iteration
     * @param generalize if true apply simple distance based generalization
     * @param maxDistance during iteration, a point will be skipped if it's distance from the
     *     previous is less than maxDistance
     */
    public PolygonIterator(Polygon p, AffineTransform at, boolean generalize, double maxDistance) {
        this(p, at, generalize);
        this.maxDistance = maxDistance;
    }

    /**
     * Sets the distance limit for point skipping during distance based generalization
     *
     * @param distance the maximum distance for point skipping
     */
    public void setMaxDistance(double distance) {
        maxDistance = distance;
    }

    /**
     * Returns the distance limit for point skipping during distance based generalization
     *
     * @return the maximum distance for distance based generalization
     */
    public double getMaxDistance() {
        return maxDistance;
    }

    /**
     * Returns the coordinates and type of the current path segment in the iteration. The return
     * value is the path-segment type: SEG_MOVETO, SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, or
     * SEG_CLOSE. A double array of length 6 must be passed in and can be used to store the
     * coordinates of the point(s). Each point is stored as a pair of double x,y coordinates.
     * SEG_MOVETO and SEG_LINETO types returns one point, SEG_QUADTO returns two points, SEG_CUBICTO
     * returns 3 points and SEG_CLOSE does not return any points.
     *
     * @param coords an array that holds the data returned from this method
     * @return the path-segment type of the current path segment.
     * @see #SEG_MOVETO
     * @see #SEG_LINETO
     * @see #SEG_QUADTO
     * @see #SEG_CUBICTO
     * @see #SEG_CLOSE
     */
    public int currentSegment(double[] coords) {
        // first make sure we're not at the last element, this prevents us from exceptions
        // in the case where coords.size() == 0
        if (currentCoord == this.coords.size()) {
            return SEG_CLOSE;
        } else if (currentCoord == 0) {
            coords[0] = this.coords.getX(0);
            coords[1] = this.coords.getY(0);
            transform(coords, 0, coords, 0, 1);

            return SEG_MOVETO;
        } else {
            coords[0] = this.coords.getX(currentCoord);
            coords[1] = this.coords.getY(currentCoord);
            transform(coords, 0, coords, 0, 1);

            return SEG_LINETO;
        }
    }

    protected void transform(double[] src, int index, double[] dest, int destIndex, int numPoints) {
        at.transform(src, index, dest, destIndex, numPoints);
    }

    /**
     * Return the winding rule for determining the interior of the path.
     *
     * @return WIND_EVEN_ODD by default.
     */
    public int getWindingRule() {
        return WIND_EVEN_ODD;
    }

    /**
     * Tests if the iteration is complete.
     *
     * @return true if all the segments have been read; false otherwise.
     */
    public boolean isDone() {
        return done;
    }

    /**
     * Moves the iterator to the next segment of the path forwards along the primary direction of
     * traversal as long as there are more points in that direction.
     */
    public void next() {
        if (currentCoord == coords.size()) {
            if (currentRing < (rings.length - 1)) {
                currentCoord = 0;
                currentRing++;
                coords = rings[currentRing].getCoordinateSequence();
            } else {
                done = true;
            }
        } else {
            if (generalize) {
                if (oldCoord == null) {
                    currentCoord++;
                    oldCoord = coords.getCoordinate(currentCoord);
                } else {
                    double distx = 0;
                    double disty = 0;

                    do {
                        currentCoord++;

                        if (currentCoord < coords.size()) {
                            distx = Math.abs(coords.getX(currentCoord) - oldCoord.x);
                            disty = Math.abs(coords.getY(currentCoord) - oldCoord.y);
                        }
                    } while (((distx * xScale) < maxDistance)
                            && ((disty * yScale) < maxDistance)
                            && (currentCoord < coords.size()));

                    if (currentCoord < coords.size()) {
                        oldCoord = coords.getCoordinate(currentCoord);
                    } else {
                        oldCoord = null;
                    }
                }
            } else {
                currentCoord++;
            }
        }
    }
}