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/*
* 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.android.setupwizardlib.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.
*
* For example, {@link com.android.setupwizardlib.items.Item} is a representation of a single item,
* typically with data provided from XML. {@link com.android.setupwizardlib.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);
}
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