GridSubsetFactory.java

/**
 * This program 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, either version 3 of the License, or
 * (at your option) any later version.
 *
 *  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.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * 
 * @author Arne Kepp, OpenGeo, Copyright 2009
 */
package org.geowebcache.grid;

import java.util.Map;
import java.util.TreeMap;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public class GridSubsetFactory {
    private static Log log = LogFactory.getLog(GridSubsetFactory.class);

    public static GridSubset createGridSubSet(GridSet gridSet) {

        GridSubset ret = createGridSubSet(gridSet, gridSet.getOriginalExtent(), 0,
                gridSet.getGridLevels().length - 1);
        return ret;
    }

    public static GridSubset createGridSubSet(GridSet gridSet, BoundingBox extent,
            Integer zoomStart, Integer zoomStop) {
        return createGridSubSet(gridSet, extent, zoomStart, zoomStop, null, null);
    }

    public static GridSubset createGridSubSet(GridSet gridSet, BoundingBox extent,
            Integer zoomStart, Integer zoomStop, Integer minCachedZoom, Integer maxCachedZoom) {

        if (gridSet == null) {
            log.error("Passed GridSet was null!");
        }

        final Grid[] gridLevels = gridSet.getGridLevels();
        final int maxLevel = gridLevels.length - 1;
        if (zoomStart == null) {
            zoomStart = 0;
        }
        if (zoomStop == null) {
            zoomStop = maxLevel;
        } else if (zoomStop > maxLevel) {
            String message = "Requested to create GridSubset with zoomStop " + zoomStop
                    + " for GridSet " + gridSet.getName() + " whose max zoom level is " + maxLevel
                    + ". Limiting GridSubset to zoomStop = " + maxLevel;
            log.warn(message);
            zoomStop = maxLevel;
        }

        Map<Integer, GridCoverage> coverages = new TreeMap<Integer, GridCoverage>();
        for (int z = zoomStart; z <= zoomStop; z++) {

            Grid level = gridLevels[z];

            long[] coverage;
            if (extent == null) {
                long maxColX = level.getNumTilesWide() - 1;
                long maxColY = level.getNumTilesHigh() - 1;
                coverage = new long[] { 0, 0, maxColX, maxColY, z };
            } else {
                coverage = gridSet.closestRectangle(z, extent);
            }

            GridCoverage gridCov = new GridCoverage(coverage);
            coverages.put(Integer.valueOf(z), gridCov);
        }

        // Save the original extent provided by the user
        BoundingBox originalExtent = extent;
        boolean fullCoverage = false;

        // Is this plain wrong? GlobalCRS84Scale, I guess the resolution forces it
        BoundingBox gridSetBounds = gridSet.getBounds();
        if (extent == null || extent.contains(gridSetBounds)) {
            fullCoverage = true;
            originalExtent = gridSetBounds;
        }

        GridSubset ret = new GridSubset(gridSet, coverages, originalExtent, fullCoverage, minCachedZoom, maxCachedZoom);
        return ret;

    }
}