com.google.gwt.event.shared.HandlerManager Maven / Gradle / Ivy
/*
* 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.shared;
import com.google.web.bindery.event.shared.Event;
/**
* Manager responsible for adding handlers to event sources and firing those
* handlers on passed in events. Primitive ancestor of {@link EventBus}, and
* used at the core of {com.google.gwt.user.client.ui.Widget}.
*
* While widget authors should continue to use
* {@link com.google.gwt.user.client.ui.Widget#addDomHandler(EventHandler, com.google.gwt.event.dom.client.DomEvent.Type)}
* and
* {@link com.google.gwt.user.client.ui.Widget#addHandler(EventHandler, com.google.gwt.event.shared.GwtEvent.Type)}
* , application developers are strongly discouraged from using a HandlerManager
* instance as a global event dispatch mechanism.
*/
public class HandlerManager implements HasHandlers {
@SuppressWarnings("deprecation")
private static class Bus extends com.google.web.bindery.event.shared.SimpleEventBus {
public Bus(boolean fireInReverseOrder) {
super(fireInReverseOrder);
}
@Override
protected void doRemove(Event.Type type, Object source, H handler) {
super.doRemove(type, source, handler);
}
@Override
protected H getHandler(Event.Type type, int index) {
return super.getHandler(type, index);
}
@Override
protected int getHandlerCount(Event.Type eventKey) {
return super.getHandlerCount(eventKey);
}
@Override
protected boolean isEventHandled(Event.Type eventKey) {
return super.isEventHandled(eventKey);
}
}
private final Bus eventBus;
// source of the events
private final Object source;
/**
* Creates a handler manager with a source to be set on all events fired via
* {@link #fireEvent(GwtEvent)}. Handlers will be fired in the order that they
* are added.
*
* @param source the default event source
*/
public HandlerManager(Object source) {
this(source, false);
}
/**
* Creates a handler manager with the given source, specifying the order in
* which handlers are fired.
*
* @param source the event source
* @param fireInReverseOrder true to fire handlers in reverse order
*/
public HandlerManager(Object source, boolean fireInReverseOrder) {
eventBus = new Bus(fireInReverseOrder);
this.source = source;
}
/**
* Adds a handler.
*
* @param The type of handler
* @param type the event type associated with this handler
* @param handler the handler
* @return the handler registration, can be stored in order to remove the
* handler later
*/
public HandlerRegistration addHandler(GwtEvent.Type type,
final H handler) {
return new LegacyHandlerWrapper(eventBus.addHandler(type, handler));
}
/**
* Fires the given event to the handlers listening to the event's type.
*
* Any exceptions thrown by handlers will be bundled into a
* {@link UmbrellaException} and then re-thrown after all handlers have
* completed. An exception thrown by a handler will not prevent other handlers
* from executing.
*
* Note, any subclass should be very careful about overriding this method, as
* adds/removes of handlers will not be safe except within this
* implementation.
*
* @param event the event
*/
public void fireEvent(GwtEvent event) {
// If it not live we should revive it.
if (!event.isLive()) {
event.revive();
}
Object oldSource = event.getSource();
event.overrideSource(source);
try {
// May throw an UmbrellaException.
eventBus.fireEvent(event);
} catch (com.google.web.bindery.event.shared.UmbrellaException e) {
throw new UmbrellaException(e.getCauses());
} finally {
if (oldSource == null) {
// This was my event, so I should kill it now that I'm done.
event.kill();
} else {
// Restoring the source for the next handler to use.
event.overrideSource(oldSource);
}
}
}
/**
* Gets the handler at the given index.
*
* @param the event handler type
* @param index the index
* @param type the handler's event type
* @return the given handler
*/
public H getHandler(GwtEvent.Type type, int index) {
return eventBus.getHandler(type, index);
}
/**
* Gets the number of handlers listening to the event type.
*
* @param type the event type
* @return the number of registered handlers
*/
public int getHandlerCount(GwtEvent.Type type) {
return eventBus.getHandlerCount(type);
}
/**
* Does this handler manager handle the given event type?
*
* @param e the event type
* @return whether the given event type is handled
*/
public boolean isEventHandled(GwtEvent.Type e) {
return eventBus.isEventHandled(e);
}
/**
* Removes the given handler from the specified event type.
*
* @param handler type
*
* @param type the event type
* @param handler the handler
*/
public void removeHandler(GwtEvent.Type type, final H handler) {
eventBus.doRemove(type, null, handler);
}
}