GWCZoomContextFinder.java

/* (c) 2016 Open Source Geospatial Foundation - all rights reserved
 * (c) 2014 - 2016 Boundless Spatial Inc.
 * This code is licensed under the GPL 2.0 license, available at the root
 * application directory.
 */

package org.geoserver.ysld;

import java.util.Set;

import javax.annotation.Nullable;

import org.geotools.ysld.parse.MedialZoomContext;
import org.geotools.ysld.parse.ZoomContext;
import org.geotools.ysld.parse.ZoomContextFinder;
import org.geowebcache.grid.GridSet;
import org.geowebcache.grid.GridSetBroker;

/**
 * ZoomContextFinder that wraps the GWC Gridset Broker.
 * 
 * @author Kevin Smith, Boundless
 *
 */
public class GWCZoomContextFinder implements ZoomContextFinder {
    
    GridSetBroker broker;
    
    public GWCZoomContextFinder(GridSetBroker broker) {
        super();
        this.broker = broker;
    }
    
    @Override
    public @Nullable ZoomContext get(String name) {
        GridSet set = broker.get(name);
        if(set!=null) {
            return new GWCZoomContext(set);
        } else {
            return null;
        }
    }
    
    @Override
    public Set<String> getNames() {
        return broker.getNames();
    }
    
    @Override
    public Set<String> getCanonicalNames() {
        return broker.getNames();
    }
    
    class GWCZoomContext extends MedialZoomContext{
        final GridSet gridset;
        
        public GWCZoomContext(GridSet gridset) {
            super();
            assert gridset!=null;
            this.gridset = gridset;
        }

        @Override
        public double getScaleDenominator(int level) {
            if(level<0) return Double.POSITIVE_INFINITY;
            if(level>=gridset.getNumLevels()) return 0;
            
            return gridset.getGrid(level).getScaleDenominator();
        }
        
        @Override
        protected double getMedialScale(int level) {
            if(level>=gridset.getNumLevels()-1) {
                return 0;
            }
            return getScaleDenominator(level)/1.005d; // Mimic TileFuser
            
            //return Math.sqrt(getScaleDenominator(level)*getScaleDenominator(level+1)); // Geometric, like other implementations
        }
        
        @Override
        public boolean isInRange(int level) {
            return level>=0 && level < gridset.getNumLevels();
        }
    }
}