com.google.gwt.event.logical.shared.AttachEvent.java Source code

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Here is the source code for com.google.gwt.event.logical.shared.AttachEvent.java

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/*
 * Copyright 2010 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.event.logical.shared;

import com.google.gwt.event.shared.EventHandler;
import com.google.gwt.event.shared.GwtEvent;

/**
 * Fired when the event source is attached to the browser's document
 * or detached from it.
 */
public class AttachEvent extends GwtEvent<AttachEvent.Handler> {

    /**
     * Implemented by objects that handle {@link AttachEvent}.
     */
    public interface Handler extends EventHandler {
        void onAttachOrDetach(AttachEvent event);
    }

    /**
     * The event type.
     */
    static Type<AttachEvent.Handler> TYPE;

    /**
     * Fires an {@link AttachEvent} on all registered handlers in the handler
     * source.
     *
     * @param <S> The handler source type
     * @param source the source of the handlers
     * @param attached whether to announce an attach or detach
     */
    public static <S extends HasAttachHandlers> void fire(S source, boolean attached) {
        if (TYPE != null) {
            AttachEvent event = new AttachEvent(attached);
            source.fireEvent(event);
        }
    }

    /**
     * Ensures the existence of the handler hook and then returns it.
     *
     * @return returns a handler hook
     */
    public static Type<AttachEvent.Handler> getType() {
        if (TYPE == null) {
            TYPE = new Type<AttachEvent.Handler>();
        }
        return TYPE;
    }

    private final boolean attached;

    /**
     * Construct a new {@link AttachEvent}.
     *
     * @param attached true if the source has been attached
     */
    protected AttachEvent(boolean attached) {
        this.attached = attached;
    }

    @Override
    public final Type<AttachEvent.Handler> getAssociatedType() {
        return TYPE;
    }

    /**
     * Returns true if this event announces that the source has been attached,
     * false if it has been detached.
     */
    public boolean isAttached() {
        return attached;
    }

    @Override
    public String toDebugString() {
        assertLive();
        return super.toDebugString() + " attached = " + attached;
    }

    @Override
    protected void dispatch(AttachEvent.Handler handler) {
        handler.onAttachOrDetach(this);
    }
}