Subversion Repositories mkgmap

/*
 * Copyright (C) 2010, 2011.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 3 or
 * 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.
 */
package uk.me.parabola.mkgmap.filters;

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

import uk.me.parabola.log.Logger;
import uk.me.parabola.mkgmap.build.MapSplitter;
import uk.me.parabola.mkgmap.general.MapElement;
import uk.me.parabola.mkgmap.general.MapShape;

/**
 * Split polygon so that it does not exceed the limits of a subdivision.  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 WanMil
 */
public class PolygonSubdivSizeSplitterFilter extends PolygonSplitterBase implements MapFilter {
        private static final Logger log = Logger.getLogger(PolygonSubdivSizeSplitterFilter.class);

        private int maxSize;

        /**
         * 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) {
                int shift = config.getShift();
                if (shift > 15)
                        shift = 16;
                // allow a size of 0x8000 to avoid splitting of generated precomp-sea polygons
                maxSize = Math.min((1<<24)-1, Math.max(MAX_SIZE << shift, 0x8000));
        }

        /**
         * Split up polygons that exceeds the limits of a subdivision.
         *
         * @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;

                if (isSizeOk(shape)) {
                        // 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)) {
                                // 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) {
                // Estimate the size taken by lines and shapes as a constant plus
                // a factor based on the number of points.
                int numPoints = shape.getPoints().size();
                int numElements = 1 + ((numPoints - 1) / PolygonSplitterFilter.MAX_POINT_IN_ELEMENT);
                int size =  numElements * 11 + numPoints * 4;
               
                if (shape.hasExtendedType()) {
                        if (size > MapSplitter.MAX_XT_SHAPES_SIZE) {
                                log.debug("XTSize larger than", MapSplitter.MAX_XT_SHAPES_SIZE);
                                return false;
                        }
                } else if (size > MapSplitter.MAX_RGN_SIZE) {
                        log.debug("RGN Size larger than", MapSplitter.MAX_RGN_SIZE);
                        return false;
                }
                int maxDim = shape.getBounds().getMaxDimension();
                if (maxDim > maxSize){
                        log.debug("Size ", maxDim," larger than ", maxSize);
                        return false;
                }
                return true;
        }

}