| /* |
| * 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. |
| * <p> |
| * 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); |
| } |