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

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Here is the source code for com.google.gwt.maps.client.overlay.GroundOverlay.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.GroundOverlayVisibilityChangedHandler;
import com.google.gwt.maps.client.event.GroundOverlayVisibilityChangedHandler.GroundOverlayVisibilityChangedEvent;
import com.google.gwt.maps.client.geom.LatLngBounds;
import com.google.gwt.maps.client.impl.GroundOverlayImpl;
import com.google.gwt.maps.client.impl.HandlerCollection;
import com.google.gwt.maps.client.impl.MapEvent;
import com.google.gwt.maps.client.impl.EventImpl.BooleanCallback;
import com.google.gwt.maps.client.overlay.Overlay.ConcreteOverlay;

/**
 * A rectangular image overlay whose boundaries are defined by a
 * {@link LatLngBounds}.
 * 
 * Example:
 * 
 * <pre>
 *  MapWidget map; = ...;
 *  Overlay overlay = new GroundOverlay(<i>url</i>, <i>bounds</i>);
 *  map.addOverlay(overlay);
 * </pre>
 * 
 * @see com.google.gwt.maps.client.MapWidget#addOverlay(Overlay)
 */
public class GroundOverlay extends ConcreteOverlay {

    public static GroundOverlay createPeer(JavaScriptObject jsoPeer) {
        return new GroundOverlay(jsoPeer);
    }

    private HandlerCollection<GroundOverlayVisibilityChangedHandler> groundOverlayVisibilityChangedHandlers;

    /**
     * Creates a new ground overlay from the given image with the specified size.
     * 
     * @param imageUrl the URL of the overlay image
     * @param bounds the rectangle defining the bounds of the overlay
     */
    public GroundOverlay(String imageUrl, LatLngBounds bounds) {
        super(GroundOverlayImpl.impl.construct(imageUrl, bounds));
    }

    GroundOverlay(JavaScriptObject jsoPeer) {
        super(jsoPeer);
    }

    /**
     * This event is fired when the visibility of the ground overlay is changed (i.e. the
     * visibility is flipped from visible to hidden or vice-versa). The
     * <code>visible</code> parameter refers to the state of the ground overlay after
     * the visibility change has happened.
     * 
     * @param handler the handler to call when this event fires.
     */
    public void addGroundOverlayVisibilityChangedHandler(final GroundOverlayVisibilityChangedHandler handler) {
        maybeInitGroundOverlayVisibilityChangeHandlers();

        groundOverlayVisibilityChangedHandlers.addHandler(handler, new BooleanCallback() {
            @Override
            public void callback(boolean visible) {
                GroundOverlayVisibilityChangedEvent e = new GroundOverlayVisibilityChangedEvent(GroundOverlay.this,
                        visible);
                handler.onVisibilityChanged(e);
            }
        });
    }

    /**
     * Returns <code>true</code> if the overlay is currently visible.
     * @return <code>true</code> if the overlay is currently visible.
     */
    public boolean isVisible() {
        return !GroundOverlayImpl.impl.isHidden(jsoPeer);
    }

    /**
     * Removes a single handler of this map previously added with
     * {@link GroundOverlay#addGroundOverlayVisibilityChangedHandler(GroundOverlayVisibilityChangedHandler)}.
     * 
     * @param handler the handler to remove
     */
    public void removeGroundOverlayVisibilityChangedHandler(GroundOverlayVisibilityChangedHandler handler) {
        if (groundOverlayVisibilityChangedHandlers != null) {
            groundOverlayVisibilityChangedHandlers.removeHandler(handler);
        }
    }

    /**
     * Sets the overlay visible by passing <code>true</code> or hide it b passing <code>false</code>.
     * @param enabled sets the overlay visible by passing <code>true</code> or hide it b passing <code>false</code>.
     */
    public void setVisible(boolean enabled) {
        if (enabled) {
            GroundOverlayImpl.impl.show(jsoPeer);
        } else {
            GroundOverlayImpl.impl.hide(jsoPeer);
        }
    }

    /**
     * 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(GroundOverlayVisibilityChangedEvent event) {
        maybeInitGroundOverlayVisibilityChangeHandlers();
        groundOverlayVisibilityChangedHandlers.trigger(event.isVisible());
    }

    /**
     * Lazy init the HandlerCollection.
     */
    private void maybeInitGroundOverlayVisibilityChangeHandlers() {
        if (groundOverlayVisibilityChangedHandlers == null) {
            groundOverlayVisibilityChangedHandlers = new HandlerCollection<GroundOverlayVisibilityChangedHandler>(
                    jsoPeer, MapEvent.VISIBILITYCHANGED);
        }
    }

}