| /* |
| * 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.view.client; |
| |
| import com.google.gwt.view.client.SelectionModel.AbstractSelectionModel; |
| |
| /** |
| * A simple selection model that allows only one object to be selected a a time. |
| * |
| * <p> |
| * Note: This class is new and its interface subject to change. |
| * </p> |
| * |
| * @param <T> the record data type |
| */ |
| public class SingleSelectionModel<T> extends AbstractSelectionModel<T> { |
| |
| private Object curKey; |
| private T curSelection; |
| |
| // Pending selection change |
| private boolean newSelected; |
| private T newSelectedObject = null; |
| |
| /** |
| * Gets the currently-selected object. |
| */ |
| public T getSelectedObject() { |
| resolveChanges(); |
| return curSelection; |
| } |
| |
| public boolean isSelected(T object) { |
| resolveChanges(); |
| if (curSelection == null || curKey == null || object == null) { |
| return false; |
| } |
| return curKey.equals(getKey(object)); |
| } |
| |
| public void setSelected(T object, boolean selected) { |
| newSelectedObject = object; |
| newSelected = selected; |
| scheduleSelectionChangeEvent(); |
| } |
| |
| @Override |
| protected void fireSelectionChangeEvent() { |
| if (isEventScheduled()) { |
| setEventCancelled(true); |
| } |
| |
| if (resolveChanges()) { |
| SelectionChangeEvent.fire(this); |
| } |
| } |
| |
| private boolean resolveChanges() { |
| if (newSelectedObject == null) { |
| return false; |
| } |
| |
| Object key = getKey(newSelectedObject); |
| boolean sameKey = curKey == null ? key == null : curKey.equals(key); |
| boolean changed = false; |
| if (newSelected) { |
| changed = !sameKey; |
| curSelection = newSelectedObject; |
| curKey = key; |
| } else if (sameKey) { |
| changed = true; |
| curSelection = null; |
| curKey = null; |
| } |
| |
| newSelectedObject = null; |
| return changed; |
| } |
| } |