com.google.gwt.maps.sample.hellomaps.client.GeoRssOverlayDemo.java Source code

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Here is the source code for com.google.gwt.maps.sample.hellomaps.client.GeoRssOverlayDemo.java

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/*
 * Copyright 2008 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.gwt.maps.sample.hellomaps.client;

import com.google.gwt.core.client.GWT;
import com.google.gwt.maps.client.MapWidget;
import com.google.gwt.maps.client.control.LargeMapControl;
import com.google.gwt.maps.client.geom.LatLng;
import com.google.gwt.maps.client.overlay.GeoXmlLoadCallback;
import com.google.gwt.maps.client.overlay.GeoXmlOverlay;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.ClickListener;
import com.google.gwt.user.client.ui.FlowPanel;
import com.google.gwt.user.client.ui.HTML;
import com.google.gwt.user.client.ui.Panel;
import com.google.gwt.user.client.ui.Widget;

/**
 * The Google Maps API supports the KML and GeoRSS data formats for displaying
 * geographic information. These data formats are added to a map using the
 * GGeoXml object, whose factory method takes the URL of a publicly accessible
 * XML file. GGeoXml placemarks are rendered as markers, while GGeoXml polylines
 * and polygons are rendered as Google Maps API polylines and polygons.
 * <GroundOverlay> elements within KML files are rendered as
 * GGroundOverlay elements on the map.
 * 
 * GeoXmlOverlay objects are added to a map using the
 * {@link MapWidget#addOverlay(com.google.gwt.maps.client.overlay.Overlay)}
 * method. (You can remove them from the map using
 * {@link MapWidget#removeOverlay(com.google.gwt.maps.client.overlay.Overlay)}.)
 * Both KML and GeoRSS XML files are supported.
 */
public class GeoRssOverlayDemo extends MapsDemo {

    private static HTML descHTML = null;

    private static final String descString = "<p>Creates a map view of the " + "contents of a Geo RSS file</p>"
            + "<p>Each entry in the RSS file is displayed as a marker.</p>\n"
            + "<p>Equivalent to the Maps JavaScript API Example: "
            + "<a href=\"http://code.google.com/apis/maps/documentation/examples/geoxml-rss.html\">"
            + "http://code.google.com/apis/maps/documentation/examples/geoxml-rss.html</a></p>\n";

    public static MapsDemoInfo init() {
        return new MapsDemoInfo() {
            @Override
            public MapsDemo createInstance() {
                return new GeoRssOverlayDemo();
            }

            @Override
            public HTML getDescriptionHTML() {
                if (descHTML == null) {
                    descHTML = new HTML(descString);
                }
                return descHTML;
            }

            @Override
            public String getName() {
                return "GeoRSS Overlays";
            }
        };
    }

    private GeoXmlOverlay geoXml;
    private boolean geoXmlShown;
    private MapWidget map;
    private Button toggleButton;

    public GeoRssOverlayDemo() {
        Panel panel = new FlowPanel();

        map = new MapWidget(LatLng.newInstance(49.496675, -102.65625), 3);
        map.setSize("640px", "480px");
        map.addControl(new LargeMapControl());
        panel.add(map);
        toggleButton = new Button("Toggle Markers");
        toggleButton.setEnabled(false);
        toggleButton.addClickListener(new ClickListener() {
            public void onClick(Widget sender) {
                if (geoXml == null) {
                    return;
                }
                if (geoXmlShown) {
                    map.removeOverlay(geoXml);
                } else {
                    map.addOverlay(geoXml);
                }
                geoXmlShown = !geoXmlShown;
            }
        });
        panel.add(toggleButton);
        initWidget(panel);

        GeoXmlOverlay.load(
                "http://api.flickr.com/services/feeds/groups_pool.gne?id=322338@N20&format=rss_200&georss=1",
                new GeoXmlLoadCallback() {
                    @Override
                    public void onFailure(String url, Throwable e) {
                        StringBuffer message = new StringBuffer("GeoRss File " + url + " failed to load");
                        if (e != null) {
                            message.append(e.toString());
                        }
                        Window.alert(message.toString());
                    }

                    @Override
                    public void onSuccess(String url, GeoXmlOverlay overlay) {
                        geoXml = overlay;
                        toggleButton.setEnabled(true);
                        map.addOverlay(geoXml);
                        GWT.log("GeoRss File " + url + "loaded successfully", null);
                        GWT.log("Default Center=" + geoXml.getDefaultCenter(), null);
                        GWT.log("Default Span=" + geoXml.getDefaultSpan(), null);
                        GWT.log("Default Bounds=" + geoXml.getDefaultBounds(), null);
                        GWT.log("Supports hide=" + geoXml.supportsHide(), null);
                    }
                });
    }

    @Override
    public void onShow() {
        map.clearOverlays();
        if (geoXml != null) {
            map.addOverlay(geoXml);
        }
        geoXmlShown = true;
    }
}