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

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Here is the source code for com.google.gwt.maps.sample.hellomaps.client.GroundOverlayDemo.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.maps.client.MapWidget;
import com.google.gwt.maps.client.control.MapTypeControl;
import com.google.gwt.maps.client.control.SmallMapControl;
import com.google.gwt.maps.client.event.GroundOverlayVisibilityChangedHandler;
import com.google.gwt.maps.client.geom.LatLng;
import com.google.gwt.maps.client.geom.LatLngBounds;
import com.google.gwt.maps.client.overlay.GroundOverlay;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.ClickListener;
import com.google.gwt.user.client.ui.HTML;
import com.google.gwt.user.client.ui.VerticalPanel;
import com.google.gwt.user.client.ui.Widget;

/**
 * This demo shows how to create a custom overlay in the form of a Rectangle and
 * add it to the map.
 */
public class GroundOverlayDemo extends MapsDemo {

    private static HTML descHTML = null;

    private static final String descString = "<p>Creates a map viewport centered on Palo Alto, CA USA.</p>"
            + "<p>Draws a ground overlay at the center of the maps window with an image of a boot.</p>\n";

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

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

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

    private MapWidget map;

    private boolean firstTime = true;
    private Button hideButton;
    private GroundOverlay groundOverlay;

    public GroundOverlayDemo() {
        VerticalPanel vp = new VerticalPanel();
        map = new MapWidget(LatLng.newInstance(37.4419, -122.1419), 13);
        vp.add(map);
        vp.setSpacing(10);
        map.setSize("500px", "500px");
        map.addControl(new SmallMapControl());
        map.addControl(new MapTypeControl());

        hideButton = new Button("Hide");
        vp.add(hideButton);
        hideButton.addClickListener(new ClickListener() {

            public void onClick(Widget sender) {
                if (groundOverlay.isVisible()) {
                    hideButton.setText("Show");
                } else {
                    hideButton.setText("Hide");
                }
                groundOverlay.setVisible(!groundOverlay.isVisible());
            }

        });
        initWidget(vp);
    }

    @Override
    public void onShow() {
        // The map's bounds are meaningless until the map has been added to the DOM
        // and sized appropriately
        if (firstTime) {
            firstTime = false;
            LatLngBounds bounds = map.getBounds();
            LatLng southWest = bounds.getSouthWest();
            LatLng northEast = bounds.getNorthEast();
            double lngDelta = (northEast.getLongitude() - southWest.getLongitude()) / 4;
            double latDelta = (northEast.getLatitude() - southWest.getLatitude()) / 4;

            // generate bounds that covers center map with half the width and height
            LatLngBounds rectBounds = LatLngBounds.newInstance(
                    LatLng.newInstance(southWest.getLatitude() + latDelta, southWest.getLongitude() + lngDelta),
                    LatLng.newInstance(northEast.getLatitude() - latDelta, northEast.getLongitude() - lngDelta));
            groundOverlay = new GroundOverlay("boot.jpg", rectBounds);
            groundOverlay.addGroundOverlayVisibilityChangedHandler(new GroundOverlayVisibilityChangedHandler() {

                public void onVisibilityChanged(GroundOverlayVisibilityChangedEvent event) {
                    if (event.isVisible()) {
                        hideButton.setText("Hide Overlay");
                    } else {
                        hideButton.setText("Show Overlay");
                    }
                }

            });
            map.addOverlay(groundOverlay);
        }
    }
}