rocket.event.client.EventPreviewAdapter.java Source code

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Here is the source code for rocket.event.client.EventPreviewAdapter.java

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/*
 * Copyright Miroslav Pokorny
 *
 * 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 rocket.event.client;

import rocket.util.client.Utilities;

import com.google.gwt.user.client.DOM;

/**
 * Convenient method which takes care of adapting a GWt raw event into a rocket
 * event and then dispatching to the appropriate handleXXX method.
 * 
 * Sub classes only need to override the appropriate handle method.
 * 
 * @author Miroslav Pokorny
 */
public class EventPreviewAdapter extends EventDispatcher implements com.google.gwt.user.client.EventPreview {

    public EventPreviewAdapter() {
    }

    /**
     * Installs this EventPreview so that it will preview all incoming events.
     * 
     */
    public void install() {
        DOM.addEventPreview(this);
    }

    /**
     * Removes this EventPreview from recieving all incoming events.
     */
    public void uninstall() {
        DOM.removeEventPreview(this);
    }

    /**
     * This method builds an Event and then dispatches to the appropriate event
     * handler method. The {@link #beforeDispatching(Event)} and
     * {@link #afterDispatching(Event)} are called before and after dispatching
     * based on the event type.
     */
    final public boolean onEventPreview(final com.google.gwt.user.client.Event rawEvent) {
        Event event = null;
        boolean cancelled = false;

        try {
            event = Event.getEvent(rawEvent);

            this.beforeDispatching(event);
            this.dispatch(event);
            this.afterDispatching(event);

            cancelled = event.isCancelled(); // FIXME is a hack should use
            // another method. stopProp eg
            // ???

        } finally {
            Utilities.destroyIfNecessary(event);
        }

        return !cancelled;
    }
}