com.google.gwt.maps.client.overlay.TrafficOverlay.java Source code

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Here is the source code for com.google.gwt.maps.client.overlay.TrafficOverlay.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.client.overlay;

import com.google.gwt.core.client.JavaScriptObject;
import com.google.gwt.maps.client.event.TrafficOverlayChangedHandler;
import com.google.gwt.maps.client.event.TrafficOverlayChangedHandler.TrafficOverlayChangedEvent;
import com.google.gwt.maps.client.impl.HandlerCollection;
import com.google.gwt.maps.client.impl.MapEvent;
import com.google.gwt.maps.client.impl.TrafficOverlayImpl;
import com.google.gwt.maps.client.impl.EventImpl.BooleanCallback;
import com.google.gwt.maps.client.overlay.Overlay.ConcreteOverlay;

/**
 * A traffic overlay object displays road traffic information. The traffic
 * overlay will only display traffic information for supported cities.
 * 
 * To add a traffic overlay to the map:
 * 
 * <pre>
 *  TrafficOverlay traffic = new TrafficOverlay();
 *  map.addOverlay(traffic);
 * </pre>
 */
public final class TrafficOverlay extends ConcreteOverlay {

    private HandlerCollection<TrafficOverlayChangedHandler> trafficOverlayChangedHandlers;

    /**
     * Creates a new traffic overlay.
     * 
     * Use {@link com.google.gwt.maps.client.MapWidget#addOverlay(Overlay)} to add
     * this overlay to the map.
     */
    public TrafficOverlay() {
        super(TrafficOverlayImpl.impl.construct());
    }

    /**
     * Construct a new traffic overlay with options.
     * See {@link TrafficOverlayOptions}
     */
    public TrafficOverlay(TrafficOverlayOptions options) {
        super(TrafficOverlayImpl.impl.construct(options));
    }

    /**
     * Create this overlay from an existing JavaScriptObject instance.
     * 
     * @param jsoPeer an existing JavaScriptObject instance.
     */
    protected TrafficOverlay(JavaScriptObject jsoPeer) {
        super(jsoPeer);
    }

    /**
     * 
     * This event is fired when the state of traffic data changes within the
     * current viewport. This event may be fired either when moving the map
     * between areas with and without traffic data or when the addition of a
     * {@link TrafficOverlay} to the map results in traffic data appearing within
     * the current viewport.
     * 
     * 
     * @param handler the handler to call when this event fires.
     */
    public void addTrafficOverlayChangedHandler(final TrafficOverlayChangedHandler handler) {
        maybeInitTrafficOverlayChangedHandlers();

        trafficOverlayChangedHandlers.addHandler(handler, new BooleanCallback() {
            @Override
            public void callback(boolean trafficInView) {
                TrafficOverlayChangedEvent e = new TrafficOverlayChangedEvent(TrafficOverlay.this, trafficInView);
                handler.onChanged(e);
            }
        });
    }

    /**
     * Removes a single handler of this map previously added with
     * {@link TrafficOverlay#addTrafficOverlayChangedHandler(TrafficOverlayChangedHandler)}
     * .
     * 
     * @param handler the handler to remove
     */
    public void removeTrafficOverlayHandler(TrafficOverlayChangedHandler handler) {
        if (trafficOverlayChangedHandlers != null) {
            trafficOverlayChangedHandlers.removeHandler(handler);
        }
    }

    /**
     * Shows or hides this overlay.
     * 
     * @param visible <code>true</code> to show the overlay, false to hide.
     */
    public void setVisible(boolean visible) {
        TrafficOverlayImpl.impl.setVisible(this, visible);
    }

    /**
     * Manually trigger the specified event on this object.
     * 
     * Note: The trigger() methods are provided for unit testing purposes only.
     * 
     * @param event an event to deliver to the handler.
     */
    void trigger(TrafficOverlayChangedEvent event) {
        maybeInitTrafficOverlayChangedHandlers();
        trafficOverlayChangedHandlers.trigger(event.isTrafficInView());
    }

    private void maybeInitTrafficOverlayChangedHandlers() {
        if (trafficOverlayChangedHandlers == null) {
            trafficOverlayChangedHandlers = new HandlerCollection<TrafficOverlayChangedHandler>(jsoPeer,
                    MapEvent.CHANGED);
        }
    }
}