| /* |
| * Copyright (C) 2015 The Android Open Source Project |
| * |
| * 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.android.setupdesign.items; |
| |
| /** |
| * Representation of zero or more items in a list. Each instance of ItemHierarchy should be capable |
| * of being wrapped in ItemAdapter and be displayed. |
| * |
| * <p>For example, {@link com.google.android.setupdesign.items.Item} is a representation of a single |
| * item, typically with data provided from XML. {@link |
| * com.google.android.setupdesign.items.ItemGroup} represents a list of child item hierarchies it |
| * contains, but itself does not do any display. |
| */ |
| public interface ItemHierarchy { |
| |
| /** |
| * Observer for any changes in this hierarchy. If anything updated that causes this hierarchy to |
| * show different content, this observer should be called. |
| */ |
| interface Observer { |
| /** |
| * Called when an underlying data update that can cause this hierarchy to show different content |
| * has occurred. |
| * |
| * <p>Note: This is a catch-all notification, but recycler view will have a harder time figuring |
| * out the animations for the change, and might even not animate the change at all. |
| */ |
| void onChanged(ItemHierarchy itemHierarchy); |
| |
| /** |
| * Called when an underlying data update that can cause changes that are local to the given |
| * items. This method indicates that there are no structural changes like inserting or removing |
| * items. |
| */ |
| void onItemRangeChanged(ItemHierarchy itemHierarchy, int positionStart, int itemCount); |
| |
| /** Called when items are inserted at the given position. */ |
| void onItemRangeInserted(ItemHierarchy itemHierarchy, int positionStart, int itemCount); |
| |
| /** Called when the given items are moved to a different position. */ |
| void onItemRangeMoved( |
| ItemHierarchy itemHierarchy, int fromPosition, int toPosition, int itemCount); |
| |
| /** Called when the given items are removed from the item hierarchy. */ |
| void onItemRangeRemoved(ItemHierarchy itemHierarchy, int positionStart, int itemCount); |
| } |
| |
| /** Register an observer to observe changes for this item hierarchy. */ |
| void registerObserver(Observer observer); |
| |
| /** Unregister a previously registered observer. */ |
| void unregisterObserver(Observer observer); |
| |
| /** @return the number of items this item hierarchy represent. */ |
| int getCount(); |
| |
| /** |
| * Get the item at position. |
| * |
| * @param position An integer from 0 to {@link #getCount()}}, which indicates the position in this |
| * item hierarchy to get the child item. |
| * @return A representation of the item at {@code position}. Must not be {@code null}. |
| */ |
| IItem getItemAt(int position); |
| |
| /** |
| * Find an item hierarchy within this hierarchy which has the given ID. Or null if no match is |
| * found. This hierarchy will be returned if our ID matches. Same restrictions for Android |
| * resource IDs apply to this ID. In fact, typically this ID is a resource ID generated from XML. |
| * |
| * @param id An ID to search for in this item hierarchy. |
| * @return An ItemHierarchy which matches the given ID. |
| */ |
| ItemHierarchy findItemById(int id); |
| } |