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/*
 * Copyright 2009 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.dom.client;

import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.NativeEvent;
import com.google.gwt.event.shared.EventHandler;
import com.google.gwt.event.shared.GwtEvent;
import com.google.gwt.event.shared.HasHandlers;

/**
 * {@link DomEvent} is a subclass of {@link GwtEvent} that provides events that
 * underlying native browser event object as well as a subclass of {@link Type}
 * that understands GWT event bits used by sinkEvents().
 * 
 * @param  handler type
 * 
 */
public abstract class DomEvent extends GwtEvent
    implements HasNativeEvent {

  /**
   * Type class used by dom event subclasses. Type is specialized for dom in
   * order to carry information about the native event.
   * 
   * @param  handler type
   */
  public static class Type extends GwtEvent.Type {
    private DomEvent flyweight;
    private String name;

    /**
     * This constructor allows dom event types to be triggered by the
     * {@link DomEvent#fireNativeEvent(com.google.gwt.dom.client.NativeEvent, HasHandlers)}
     * method. It should only be used by implementors supporting new dom events.
     * 
     * 

* Any such dom event type must act as a flyweight around a native event * object. *

* * @param eventName the raw native event name * @param flyweight the instance that will be used as a flyweight to wrap a * native event */ public Type(String eventName, DomEvent flyweight) { this.flyweight = flyweight; // Until we have eager clinits implemented, we are manually initializing // DomEvent here. if (registered == null) { init(); } registered.unsafePut(eventName, this); name = eventName; } /** * Gets the name associated with this event type. * * @return the name of this event type */ public String getName() { return name; } } private static PrivateMap> registered; /** * Fires the given native event on the specified handlers. * * @param nativeEvent the native event * @param handlerSource the source of the handlers to fire */ public static void fireNativeEvent(NativeEvent nativeEvent, HasHandlers handlerSource) { fireNativeEvent(nativeEvent, handlerSource, null); } /** * Fires the given native event on the specified handlers. * * @param nativeEvent the native event * @param handlerSource the source of the handlers to fire * @param relativeElem the element relative to which event coordinates will be * measured */ public static void fireNativeEvent(NativeEvent nativeEvent, HasHandlers handlerSource, Element relativeElem) { assert nativeEvent != null : "nativeEvent must not be null"; if (registered != null) { final DomEvent.Type typeKey = registered.unsafeGet(nativeEvent.getType()); if (typeKey != null) { // Store and restore native event just in case we are in recursive // loop. NativeEvent currentNative = typeKey.flyweight.nativeEvent; Element currentRelativeElem = typeKey.flyweight.relativeElem; typeKey.flyweight.setNativeEvent(nativeEvent); typeKey.flyweight.setRelativeElement(relativeElem); handlerSource.fireEvent(typeKey.flyweight); typeKey.flyweight.setNativeEvent(currentNative); typeKey.flyweight.setRelativeElement(currentRelativeElem); } } } // This method can go away once we have eager clinits. static void init() { registered = new PrivateMap>(); } private NativeEvent nativeEvent; private Element relativeElem; @Override public abstract DomEvent.Type getAssociatedType(); public final NativeEvent getNativeEvent() { assertLive(); return nativeEvent; } /** * Gets the element relative to which event coordinates will be measured. * If this element is null, event coordinates will be measured * relative to the window's client area. * * @return the event's relative element */ public final Element getRelativeElement() { assertLive(); return relativeElem; } /** * Prevents the wrapped native event's default action. */ public void preventDefault() { assertLive(); nativeEvent.preventDefault(); } /** * Sets the native event associated with this dom event. In general, dom * events should be fired using the static firing methods. * * @param nativeEvent the native event */ public final void setNativeEvent(NativeEvent nativeEvent) { this.nativeEvent = nativeEvent; } /** * Gets the element relative to which event coordinates will be measured. * * @param relativeElem the event's relative element */ public void setRelativeElement(Element relativeElem) { this.relativeElem = relativeElem; } /** * Stops the propagation of the underlying native event. */ public void stopPropagation() { assertLive(); nativeEvent.stopPropagation(); } }




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