com.nitrous.gwt.earth.client.demo.ViewChangeDemo.java Source code

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Here is the source code for com.nitrous.gwt.earth.client.demo.ViewChangeDemo.java

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/*
 * Copyright 2012 Nick Kerr
 *
 *   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.nitrous.gwt.earth.client.demo;

import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.dom.client.Style.Unit;
import com.google.gwt.event.shared.HandlerRegistration;
import com.google.gwt.user.client.Timer;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.DockLayoutPanel;
import com.google.gwt.user.client.ui.HasHorizontalAlignment;
import com.google.gwt.user.client.ui.HorizontalPanel;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.RootLayoutPanel;
import com.google.gwt.user.client.ui.VerticalPanel;
import com.nitrous.gwt.earth.client.api.GELayerId;
import com.nitrous.gwt.earth.client.api.GEPlugin;
import com.nitrous.gwt.earth.client.api.GEPluginReadyListener;
import com.nitrous.gwt.earth.client.api.GEVisibility;
import com.nitrous.gwt.earth.client.api.GoogleEarth;
import com.nitrous.gwt.earth.client.api.GoogleEarthWidget;
import com.nitrous.gwt.earth.client.api.event.ViewChangeListener;

/**
 * A GWT implementation of the demo found <a href="http://code.google.com/apis/ajax/playground/?exp=earth#viewchange_event_%28and_viewchangebegin,_viewchangeend%29">here</a>.
 * 
 * @author nick
 * 
 */
public class ViewChangeDemo implements EntryPoint {

    private GoogleEarthWidget earth;

    // this can be used to remove the view change listener
    private HandlerRegistration eventListenerRegistration;

    private Label viewChangeEndCountLabel;
    private int viewChangeEndCount = 0;
    private Label viewChangedLabel;
    private static final String CHANGE_END_TEXT = "viewchangeend count: ";

    public void onModuleLoad() {
        // Load the Earth API
        GoogleEarth.loadApi(new Runnable() {
            @Override
            public void run() {
                // start the application
                onApiLoaded();
            }
        });
    }

    /**
     * The Google earth API has loaded, start the application
     */
    private void onApiLoaded() {
        // construct the UI widget
        earth = new GoogleEarthWidget();

        // register a listener to be notified when the earth plug-in has loaded
        earth.addPluginReadyListener(new GEPluginReadyListener() {
            public void pluginReady(GEPlugin ge) {
                // show map content once the plugin has loaded
                loadMapContent();
            }

            public void pluginInitFailure() {
                // failure!
                Window.alert("Failed to initialize Google Earth Plug-in");
            }
        });

        VerticalPanel labels = new VerticalPanel();
        viewChangeEndCountLabel = new Label(CHANGE_END_TEXT + 0);
        viewChangedLabel = new Label("View Changed!");
        labels.add(viewChangeEndCountLabel);
        labels.add(viewChangedLabel);

        HorizontalPanel topPanel = new HorizontalPanel();
        topPanel.setWidth("100%");
        topPanel.setHorizontalAlignment(HasHorizontalAlignment.ALIGN_CENTER);
        topPanel.add(labels);

        DockLayoutPanel layout = new DockLayoutPanel(Unit.PX);
        layout.addNorth(topPanel, 40D);
        layout.add(earth);
        RootLayoutPanel.get().add(layout);

        viewChangedLabel.getElement().setAttribute("style",
                "background-color: #a00; color: #fff; font-weight: bold;");
        viewChangedLabel.setVisible(false);

        // begin loading the Google Earth Plug-in
        earth.init();
    }

    private Timer vcTimeout = null;

    /**
     * Display content on the map
     */
    private void loadMapContent() {
        // The GEPlugin is the core class and is a great place to start browsing
        // the API
        GEPlugin ge = earth.getGEPlugin();
        ge.getWindow().setVisibility(true);

        ge.getNavigationControl().setVisibility(GEVisibility.VISIBILITY_AUTO);

        // add some layers
        ge.enableLayer(GELayerId.LAYER_BORDERS, true);
        ge.enableLayer(GELayerId.LAYER_ROADS, true);

        // the timer that will be used to hid the label after 250ms of inactivity
        vcTimeout = new Timer() {
            @Override
            public void run() {
                viewChangedLabel.setVisible(false);
            }
        };

        // register the view change listener to hide/show the label and update the view change end count label
        eventListenerRegistration = ge.getView().addViewChangeListener(new ViewChangeListener() {

            @Override
            public void onViewChange() {
                viewChangedLabel.setVisible(true);
                //reschedule the timer to hide the 'view changed' message after 250ms of inactivity
                if (vcTimeout != null) {
                    vcTimeout.cancel();
                }
                vcTimeout.schedule(250);

            }

            @Override
            public void onViewChangeBegin() {
            }

            @Override
            public void onViewChangeEnd() {
                viewChangeEndCount++;
                viewChangeEndCountLabel.setText(CHANGE_END_TEXT + viewChangeEndCount);
            }
        });

    }

}