com.google.gwt.activity.shared.Activity Maven / Gradle / Ivy
/*
* 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.activity.shared;
import com.google.gwt.event.shared.EventBus;
import com.google.gwt.user.client.ui.AcceptsOneWidget;
/**
* Implemented by objects that control a piece of user interface, with a life
* cycle managed by an {@link ActivityManager}, in response to
* {@link com.google.gwt.place.shared.PlaceChangeEvent} events as the user
* navigates through the app.
*/
public interface Activity {
/**
* Called when the user is trying to navigate away from this activity.
*
* @return A message to display to the user, e.g. to warn of unsaved work, or
* null to say nothing
*/
String mayStop();
/**
* Called when {@link #start} has not yet replied to its callback, but the
* user has lost interest.
*/
void onCancel();
/**
* Called when the Activity's widget has been removed from view. All event
* handlers it registered will have been removed before this method is called.
*/
void onStop();
/**
* Called when the Activity should ready its widget for the user. When the
* widget is ready (typically after an RPC response has been received),
* receiver should present it by calling
* {@link AcceptsOneWidget#setWidget} on the given panel.
*
* Any handlers attached to the provided event bus will be de-registered when
* the activity is stopped, so activities will rarely need to hold on to the
* {@link com.google.gwt.event.shared.HandlerRegistration HandlerRegistration}
* instances returned by {@link EventBus#addHandler}.
*
* @param panel the panel to display this activity's widget when it is ready
* @param eventBus the event bus
*/
void start(AcceptsOneWidget panel, EventBus eventBus);
}