MGMapsConverter.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.mgmaps;

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 MGMapsConverter extends Service {
    public static final String SERVICE_MGMAPS = "mgmaps";

    private StorageBroker sb;
    
    private TileLayerDispatcher tld;
    
    private GridSetBroker gsb;
    
    /**
     * Protected no-argument constructor to allow run-time instrumentation
     */
    protected MGMapsConverter() {
        super(SERVICE_MGMAPS);
    }
    
    public MGMapsConverter(StorageBroker sb, TileLayerDispatcher tld, GridSetBroker gsb) {
        super(SERVICE_MGMAPS);
        
        this.sb = sb;
        this.tld = tld;
        this.gsb = gsb;
    }

    public ConveyorTile getConveyor(HttpServletRequest request, HttpServletResponse response)
    throws ServiceException {
        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 = MGMapsConverter.convert(Integer.parseInt(strZoom),
                Integer.parseInt(strX), Integer.parseInt(strY));

        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, null, 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
     * 
     * Modified by JaakL for mgmaps zoom understanding: zoom = 17 - zoom
     * 
     * @param quadKey
     * @return
     */
    public static long[] convert(long zoomLevel, long x, long y) throws ServiceException {
        if(zoomLevel > 17) {
            throw new ServiceException("Zoomlevel cannot be greater than 17 for Mobile GMaps");
        }
        // Extent is the total number of tiles in y direction
        long newZoom = 17 - zoomLevel;
        long extent = (long) Math.pow(2, newZoom);

        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, newZoom };

        return gridLoc;
    }
}