source: josm/src/org/openstreetmap/josm/gui/layer/WmsServerLayer.java@ 104

package org.openstreetmap.josm.gui.layer;

import static org.openstreetmap.josm.tools.I18n.tr;

import java.awt.Component;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Point;

import javax.swing.Icon;
import javax.swing.JMenuItem;
import javax.swing.JSeparator;

import org.openstreetmap.josm.Main;
import org.openstreetmap.josm.data.coor.EastNorth;
import org.openstreetmap.josm.data.coor.LatLon;
import org.openstreetmap.josm.data.osm.visitor.BoundingXYVisitor;
import org.openstreetmap.josm.data.projection.Projection;
import org.openstreetmap.josm.gui.MapView;
import org.openstreetmap.josm.gui.dialogs.LayerList;
import org.openstreetmap.josm.gui.dialogs.LayerListPopup;
import org.openstreetmap.josm.tools.ImageProvider;
import org.openstreetmap.josm.tools.TileCache;

/**
 * This is a layer that grabs the current screen from an WMS server. The data
 * fetched this way is tiled and cached to the disc to reduce server load.
 */
public class WmsServerLayer extends Layer {

        private static Icon icon = ImageProvider.get("layer/wms");

        private final TileCache cache;

        private final String url;


        public WmsServerLayer(String url) {
                super(url.indexOf('/') != -1 ? url.substring(url.indexOf('/')+1) : url);

                // to calculate the world dimension, we assume that the projection does
                // not have problems with translating longitude to a correct scale.
                // Next to that, the projection must be linear dependend on the lat/lon
                // unprojected scale.
                if (Projection.MAX_LON != 180)
                        throw new IllegalArgumentException(tr("Wrong longitude transformation for tile cache. Can't operate on {0}",Main.proj));

                this.url = url;
                cache = new TileCache(url);
        }

        @Override public Icon getIcon() {
                return icon;
        }

        @Override public String getToolTipText() {
                return tr("WMS layer: {0}", url);
        }

        @Override public boolean isMergable(Layer other) {
                return false;
        }

        @Override public void mergeFrom(Layer from) {
        }

        @Override public void paint(Graphics g, final MapView mv) {
//              EastNorth max = mv.getEastNorth(mv.getWidth(),0);
//              EastNorth min = mv.getEastNorth(0,mv.getHeight());
//              double width = max.east() - min.east();
//              double height = max.north() - min.north();
//              double tilesX = mv.getWidth() / TileCache.TILESIZE;
//              double tilesY = mv.getHeight() / TileCache.TILESIZE;

                // getting zoom level
                int zoom = 0;
                for (double w = mv.getScale(); w <= TileCache.worldDimension; w *= 2)
                        zoom++;
                LatLon oneTile = Main.proj.eastNorth2latlon(new EastNorth(
                                TileCache.TILESIZE * mv.getScale(),
                                TileCache.TILESIZE * mv.getScale()));
                if (oneTile.lat() > Projection.MAX_LAT || oneTile.lon() > Projection.MAX_LON) {
                        // just display the whole world
                        Image img = cache.get(0,0);
                        Point scr1 = mv.getPoint(Main.proj.latlon2eastNorth(new LatLon(Projection.MAX_LAT, -Projection.MAX_LON)));
                        Point scr2 = mv.getPoint(Main.proj.latlon2eastNorth(new LatLon(-Projection.MAX_LAT, Projection.MAX_LON)));
                        g.drawImage(img, scr1.x, scr1.y, scr2.x, scr2.y, 0, 0, TileCache.TILESIZE, TileCache.TILESIZE, null);
                }

//              TileCache.TileInformation info = TileCache.pos2tile(min, zoom);
                //System.out.println(url+"bbox="+info.min.lon()+","+info.min.lat()+","+info.max.lon()+","+info.max.lat());
        }

        @Override public void visitBoundingBox(BoundingXYVisitor v) {
                // doesn't have a bounding box
        }

        @Override public Object getInfoComponent() {
                return getToolTipText();
        }

        @Override public Component[] getMenuEntries() {
                return new Component[]{
                                new JMenuItem(new LayerList.ShowHideLayerAction(this)),
                                new JMenuItem(new LayerList.DeleteLayerAction(this)),
                                new JSeparator(),
                                new JMenuItem(new LayerListPopup.InfoAction(this))};
    }
}