Subversion Repositories mkgmap

/*
 * Copyright (C) 2007 Steve Ratcliffe
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 *
 *  This program 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 General Public License for more details.
 *
 *
 * Author: Steve Ratcliffe
 * Create date: Dec 2, 2007
 */
package uk.me.parabola.mkgmap.filters;

import java.util.ArrayList;
import java.util.List;

import uk.me.parabola.imgfmt.app.Area;
import uk.me.parabola.mkgmap.general.MapElement;
import uk.me.parabola.mkgmap.general.MapShape;

/**
 * Split polygons for physical size (rather than number of points).  The plan
 * here is simple, if its too big, then cut it in half.  As we always cut the largest
 * dimension, then we will soon enough have cut it down to be small enough.
 *
 * @author Steve Ratcliffe
 */
public class PolygonSizeSplitterFilter extends PolygonSplitterBase implements MapFilter {
        private int shift;

        /**
         * Get the scale factor so that we don't over split.
         *
         * @param config Configuration information, giving parameters of the map level
         * that is being produced through this filter.
         */
        public void init(FilterConfig config) {
                shift = config.getShift();
                if (shift > 15)
                        shift = 16;
        }

        /**
         * Split up polygons that are too big.
         *
         * @param element A map element, only polygons will be processed.
         * @param next  This is used to pass the possibly transformed element onward.
         */
        public void doFilter(MapElement element, MapFilterChain next) {
                assert element instanceof MapShape;
                MapShape shape = (MapShape) element;

                int maxSize = MAX_SIZE << shift;
                if (isSizeOk(shape, maxSize)) {
                        // This is ok let it through and return.
                        next.doFilter(element);
                        return;
                }

                List<MapShape> outputs = new ArrayList<MapShape>();

                // Do an initial split
                split(shape, outputs);

                // Now check that all the resulting parts are also small enough.
                // NOTE: the end condition is changed from within the loop.
                for (int i = 0; i < outputs.size(); i++) {
                        MapShape s = outputs.get(i);
                        if (!isSizeOk(s, maxSize)) {
                                // Not small enough, so remove it and split it again.  The resulting
                                // pieces will be placed at the end of the list and will be
                                // picked up later on.
                                outputs.set(i, null);
                                split(s, outputs);
                        }
                }

                // Now add all to the chain.
                for (MapShape s : outputs) {
                        if (s == null)
                                continue;
                        next.doFilter(s);
                }
        }

        private boolean isSizeOk(MapShape shape, int maxSize) {
                if (shape.getType() == 0x4a)
                        return true;
                Area bounds = shape.getBounds();
                return bounds.getMaxDimension() < maxSize
                                && bounds.getWidth() < 0x7fff
                                && bounds.getHeight() < 0x7fff
                                ;
        }

}