HttpWmsTileDataSource.java

package com.nutiteq.advancedmap3.datasource;

import android.net.Uri;

import com.nutiteq.core.MapBounds;
import com.nutiteq.core.MapPos;
import com.nutiteq.core.MapTile;
import com.nutiteq.datasources.HTTPTileDataSource;
import com.nutiteq.projections.Projection;

/**
 * A custom tile source makes WMS request. Supports only WGS84 (EPSG:4326) requests
 * 
*/
public class HttpWmsTileDataSource extends HTTPTileDataSource {
   
    
    private String baseUrl;

    private String layer;
    private String format;
    private String style;
    private boolean wgsWms;
    private Projection projection;
    
    private int tileSize = 256;
    

	/**
	 * Creates WMS DataSource, based on tiles. Map service must support EPSG:3857 or EPSG:4326. 
	 *     - EPSG:3857 has full compatibility and accuracy, 
	 *     - many services with EPSG:4326 work also, but on low zooms (world view) it is inaccurate,
	 *     because map display projection is always EPSG:3857 (in SDK 3.0)
	 *     
	 *     Only GetMap is implemented
	 * 
	 * @param minZoom minimal zoom
	 * @param maxZoom max zoom for map server
	 * @param proj datasource projection, currently should be EPSG:3857
	 * @param wgsWms false - uses EPSG:3857 for server, true - uses WGS84 (EPSG:4326) which is less accurate in low zooms
	 * @param baseUrl You need to configure direct map URL, GetCapabilities is NOT used here
	 * @param style - usually empty string, comma separated
	 * @param layer comma-separated list of layers
	 * @param format e.g. image/png, image/jpeg
	 */
	public HttpWmsTileDataSource(int minZoom, int maxZoom, Projection proj, boolean wgsWms, 
            String baseUrl, String style, String layer, String format) {
		super(minZoom, maxZoom, baseUrl);
        this.baseUrl = baseUrl;
        this.style = style;
        this.layer = layer;
        this.format = format;
        this.wgsWms = wgsWms;
        this.projection = proj;
	}

    @Override
    protected String buildTileUrl(MapTile tile) {
        
        String srs = "EPSG:3857";
        String bbox = getTileBbox(tile);

        if(wgsWms){
            srs =  "EPSG:4326";
        }
        
        Uri.Builder uri = createBaseUri("GetMap", srs);
        uri.appendQueryParameter("BBOX", bbox);
        return uri.build().toString();
    }
	
    private Uri.Builder createBaseUri(String request, String srs) {
        Uri.Builder uri = Uri.parse(baseUrl).buildUpon();
        uri.appendQueryParameter("LAYERS", layer);
        uri.appendQueryParameter("FORMAT", format);
        uri.appendQueryParameter("SERVICE", "WMS");
        uri.appendQueryParameter("VERSION", "1.1.0");
        uri.appendQueryParameter("REQUEST", request);
        uri.appendQueryParameter("STYLES", style);
        uri.appendQueryParameter("EXCEPTIONS", "application/vnd.ogc.se_inimage");
        uri.appendQueryParameter("SRS", srs);
        uri.appendQueryParameter("WIDTH", Integer.toString(tileSize));
        uri.appendQueryParameter("HEIGHT", Integer.toString(tileSize));
        return uri;
    }
    
    private String getTileBbox(MapTile tile) {
        
        MapBounds envelope = tileBounds(tile.getX(), tile.getY(), tile.getZoom(), projection);

        // Convert corners to WGS84 if maps server needs it.
        if(wgsWms){
            envelope = new MapBounds(projection.toWgs84(envelope.getMin()),projection.toWgs84(envelope.getMax()));
        }
        
        String bbox = ""
                + envelope.getMin().getX() + "," + envelope.getMin().getY() + ","
                + envelope.getMax().getX() + "," + envelope.getMax().getY();
        return bbox;
    }
    
    public MapBounds tileBounds(int tx, int ty, int zoom, Projection proj) {
        
        MapBounds bounds = proj.getBounds();
        
        double boundWidth = bounds.getMax().getX() - bounds.getMin().getX();
        double boundHeight = bounds.getMax().getY() - bounds.getMin().getY();
        
        int xCount = Math.max(1, (int) Math.round(boundWidth / boundHeight));
        int yCount = Math.max(1, (int) Math.round(boundHeight / boundWidth));

        double resx = boundWidth / xCount / (tileSize * (double) (1<<(zoom)));
        double resy = boundHeight / yCount / (tileSize * (double) (1<<(zoom)));

        double minx = ((double) tx + 0) * tileSize * resx + bounds.getMin().getX();
        double maxx = ((double) tx + 1) * tileSize * resx +  bounds.getMin().getX();
        double miny = -((double) ty + 1) * tileSize * resy +  bounds.getMax().getY();
        double maxy = -((double) ty + 0) * tileSize * resy + bounds.getMax().getY();
        
        MapBounds env = new MapBounds(new MapPos(minx,miny), new MapPos(maxx,maxy));
        
        return env;
    }




}