GMapsConverter.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, The Open Planning Project, Copyright 2008
 */
package org.geowebcache.service.gmaps;

import java.util.Map;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.geowebcache.GeoWebCacheException;
import org.geowebcache.conveyor.ConveyorTile;
import org.geowebcache.grid.GridSetBroker;
import org.geowebcache.layer.TileLayer;
import org.geowebcache.layer.TileLayerDispatcher;
import org.geowebcache.mime.MimeException;
import org.geowebcache.mime.MimeType;
import org.geowebcache.service.Service;
import org.geowebcache.service.ServiceException;
import org.geowebcache.storage.StorageBroker;
import org.geowebcache.util.ServletUtils;

/**
 * Class to convert from Google Maps coordinates into the internal representation of a tile.
 */
public class GMapsConverter extends Service {
    public static final String SERVICE_GMAPS = "gmaps";

    private StorageBroker sb;

    private TileLayerDispatcher tld;

    private GridSetBroker gsb;

    /**
     * Protected no-argument constructor to allow run-time instrumentation
     */
    protected GMapsConverter() {
        super(SERVICE_GMAPS);
    }
    
    public GMapsConverter(StorageBroker sb, TileLayerDispatcher tld, GridSetBroker gsb) {
        super(SERVICE_GMAPS);

        this.sb = sb;
        this.tld = tld;
        this.gsb = gsb;
    }

    public ConveyorTile getConveyor(HttpServletRequest request, HttpServletResponse response)
            throws ServiceException, GeoWebCacheException {
        String layerId = super.getLayersParameter(request);

        String encoding = request.getCharacterEncoding();

        Map<String, String[]> params = request.getParameterMap();
        String strFormat = ServletUtils.stringFromMap(params, encoding, "format");
        String strZoom = ServletUtils.stringFromMap(params, encoding, "zoom");
        String strX = ServletUtils.stringFromMap(params, encoding, "x");
        String strY = ServletUtils.stringFromMap(params, encoding, "y");
        String strCached = ServletUtils.stringFromMap(params, encoding, "cached");
        String strMetaTiled = ServletUtils.stringFromMap(params, encoding, "metatiled");

        long[] gridLoc = GMapsConverter.convert(Integer.parseInt(strZoom), Integer.parseInt(strX),
                Integer.parseInt(strY));

        String layers = ServletUtils.stringFromMap(params, encoding, "layers");
        if (layers == null || layers.length() == 0) {
            layers = ServletUtils.stringFromMap(params, encoding, "layer");
        }

        TileLayer tileLayer = tld.getTileLayer(layers);
        Map<String, String> filteringParameters = tileLayer.getModifiableParameters(params, encoding);

        MimeType mimeType = null;
        try {
            if (strFormat == null) {
                strFormat = "image/png";
            }
            mimeType = MimeType.createFromFormat(strFormat);
        } catch (MimeException me) {
            throw new ServiceException("Unable to determine requested format, " + strFormat);
        }

        ConveyorTile ret = new ConveyorTile(sb, layerId, gsb.WORLD_EPSG3857.getName(), gridLoc,
                mimeType, filteringParameters, request, response);

        if (strCached != null && !Boolean.parseBoolean(strCached)) {
            ret.setRequestHandler(ConveyorTile.RequestHandler.SERVICE);

            if (strMetaTiled != null && !Boolean.parseBoolean(strMetaTiled)) {
                ret.setHint("not_cached,not_metatiled");
            } else {
                ret.setHint("not_cached");
            }
        }

        return ret;
    }

    /**
     * NB The following code is shared across Google Maps, Mobile Google Maps and Virtual Earth
     */
    public void handleRequest(ConveyorTile tile) throws GeoWebCacheException {
        if (tile.getHint() != null) {
            // boolean requestTiled = true;

            if (tile.getHint().equals("not_cached,not_metatiled")) {
                // requestTiled = false;
            } else if (!tile.getHint().equals("not_cached")) {
                throw new GeoWebCacheException("Hint " + tile.getHint() + " is not known.");
            }

            TileLayer tl = tld.getTileLayer(tile.getLayerId());

            if (tl == null) {
                throw new GeoWebCacheException("Unknown layer " + tile.getLayerId());
            }

            if (!tl.isCacheBypassAllowed().booleanValue()) {
                throw new GeoWebCacheException("Layer " + tile.getLayerId()
                        + " is not configured to allow bypassing the cache.");
            }

            tile.setTileLayer(tl);
            tl.getNoncachedTile(tile);

            Service.writeTileResponse(tile, false);
        }
    }

    /**
     * Convert Google's tiling coordinates into an {x,y,x}
     * 
     * see http://code.google.com/apis/maps/documentation/overlays.html#Custom_Map_Types
     * 
     * @param quadKey
     * @return
     */
    public static long[] convert(long zoomLevel, long x, long y) throws ServiceException {
        // Extent is the total number of tiles in y direction
        long extent = (long) Math.pow(2, zoomLevel);

        if (x < 0 || x > extent - 1) {
            throw new ServiceException("The X coordinate is not sane: " + x);
        }

        if (y < 0 || y > extent - 1) {
            throw new ServiceException("The Y coordinate is not sane: " + y);
        }

        // xPos and yPos correspond to the top left hand corner
        long[] gridLoc = { x, extent - y - 1, zoomLevel };

        return gridLoc;
    }
}