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/*
* Copyright (C) 2014 darnmason
*
* 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.
*/
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.view.ViewGroup;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* <p>
* RecyclerView adapter designed to wrap an existing adapter allowing the addition of
* header views and footer views.
* </p>
* <p>
* I implemented it to aid with the transition from ListView to RecyclerView where the ListView's
* addHeaderView and addFooterView methods were used. Using this class you may initialize your
* header views in the Fragment/Activity and add them to the adapter in the same way you used to
* add them to a ListView.
* </p>
* <p>
* I also required to be able to swap out multiple adapters with different content, therefore
* setAdapter may be called multiple times.
* </p>
* Created by darnmason on 07/11/2014.
*/
public class HeaderViewRecyclerAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private static final int HEADERS_START = Integer.MIN_VALUE;
private static final int FOOTERS_START = Integer.MIN_VALUE + 10;
private static final int ITEMS_START = Integer.MIN_VALUE + 20;
private static final int ADAPTER_MAX_TYPES = 100;
private RecyclerView.Adapter mWrappedAdapter;
private List<View> mHeaderViews, mFooterViews;
private Map<Class, Integer> mItemTypesOffset;
/**
* Construct a new header view recycler adapter
* @param adapter The underlying adapter to wrap
*/
public HeaderViewRecyclerAdapter(RecyclerView.Adapter adapter) {
mHeaderViews = new ArrayList<View>();
mFooterViews = new ArrayList<View>();
mItemTypesOffset = new HashMap<Class, Integer>();
setWrappedAdapter(adapter);
}
/**
* Replaces the underlying adapter, notifying RecyclerView of changes
* @param adapter The new adapter to wrap
*/
public void setAdapter(RecyclerView.Adapter adapter) {
if(mWrappedAdapter != null && mWrappedAdapter.getItemCount() > 0) {
notifyItemRangeRemoved(getHeaderCount(), mWrappedAdapter.getItemCount());
}
setWrappedAdapter(adapter);
notifyItemRangeInserted(getHeaderCount(), mWrappedAdapter.getItemCount());
}
@Override
public int getItemViewType(int position) {
int hCount = getHeaderCount();
if (position < hCount) return HEADERS_START + position;
else {
int itemCount = mWrappedAdapter.getItemCount();
if (position < hCount + itemCount) {
return getAdapterTypeOffset() + mWrappedAdapter.getItemViewType(position - hCount);
}
else return FOOTERS_START + position - hCount - itemCount;
}
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
if (viewType < HEADERS_START + getHeaderCount())
return new StaticViewHolder(mHeaderViews.get(viewType - HEADERS_START));
else if (viewType < FOOTERS_START + getFooterCount())
return new StaticViewHolder(mFooterViews.get(viewType - FOOTERS_START));
else {
return mWrappedAdapter.onCreateViewHolder(viewGroup, viewType - getAdapterTypeOffset());
}
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {
int hCount = getHeaderCount();
if (position >= hCount && position < hCount + mWrappedAdapter.getItemCount())
mWrappedAdapter.onBindViewHolder(viewHolder, position - hCount);
}
/**
* Add a static view to appear at the start of the RecyclerView. Headers are displayed in the
* order they were added.
* @param view The header view to add
*/
public void addHeaderView(View view) {
mHeaderViews.add(view);
}
/**
* Add a static view to appear at the end of the RecyclerView. Footers are displayed in the
* order they were added.
* @param view The footer view to add
*/
public void addFooterView(View view) {
mFooterViews.add(view);
}
@Override
public int getItemCount() {
return getHeaderCount() + getFooterCount() + getWrappedItemCount();
}
/**
* @return The item count in the underlying adapter
*/
public int getWrappedItemCount() {
return mWrappedAdapter.getItemCount();
}
/**
* @return The number of header views added
*/
public int getHeaderCount() {
return mHeaderViews.size();
}
/**
* @return The number of footer views added
*/
public int getFooterCount() {
return mFooterViews.size();
}
private void setWrappedAdapter(RecyclerView.Adapter adapter) {
if (mWrappedAdapter != null) mWrappedAdapter.unregisterAdapterDataObserver(mDataObserver);
mWrappedAdapter = adapter;
Class adapterClass = mWrappedAdapter.getClass();
if(!mItemTypesOffset.containsKey(adapterClass)) putAdapterTypeOffset(adapterClass);
mWrappedAdapter.registerAdapterDataObserver(mDataObserver);
}
private void putAdapterTypeOffset(Class adapterClass) {
mItemTypesOffset.put(adapterClass, ITEMS_START + mItemTypesOffset.size() * ADAPTER_MAX_TYPES);
}
private int getAdapterTypeOffset() {
return mItemTypesOffset.get(mWrappedAdapter.getClass());
}
private RecyclerView.AdapterDataObserver mDataObserver = new RecyclerView.AdapterDataObserver() {
@Override
public void onChanged() {
super.onChanged();
notifyDataSetChanged();
}
@Override
public void onItemRangeChanged(int positionStart, int itemCount) {
super.onItemRangeChanged(positionStart, itemCount);
notifyItemRangeChanged(positionStart + getHeaderCount(), itemCount);
}
@Override
public void onItemRangeInserted(int positionStart, int itemCount) {
super.onItemRangeInserted(positionStart, itemCount);
notifyItemRangeInserted(positionStart + getHeaderCount(), itemCount);
}
@Override
public void onItemRangeRemoved(int positionStart, int itemCount) {
super.onItemRangeRemoved(positionStart, itemCount);
notifyItemRangeRemoved(positionStart + getHeaderCount(), itemCount);
}
@Override
public void onItemRangeMoved(int fromPosition, int toPosition, int itemCount) {
super.onItemRangeMoved(fromPosition, toPosition, itemCount);
int hCount = getHeaderCount();
// TODO: No notifyItemRangeMoved method?
notifyItemRangeChanged(fromPosition + hCount, toPosition + hCount + itemCount);
}
};
private static class StaticViewHolder extends RecyclerView.ViewHolder {
public StaticViewHolder(View itemView) {
super(itemView);
}
}
}
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