package com.getchute.android.photopickerplus.ui.adapter;
import android.content.Context;
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;
/**
* The MergeRecyclerAdapter is inspired by the cwac-merge adapter, but for
* the RecyclerView.
*
* This adapter essentially merges a collection of adapters/views into one adapter.
*
* Methods are provided for adding single views or a list of views, but under the hood
* these views are then put into an adapter themselves, even if the adapter only holds the
* one view.
*
* RecyclerView Adapters must implement both the android.support.v7.widget.RecyclerView.Adapter#onCreateViewHolder(android.view
* .ViewGroup, int)
* and {@link android.support.v7.widget.RecyclerView.Adapter#onBindViewHolder(android.support.v7.widget.RecyclerView.ViewHolder,
* int)} methods, as opposed to just the {@link android.widget.BaseAdapter#getView(int, android.view.View,
* android.view.ViewGroup)} method in a ListView Adapter.
*
* Because the android.support.v7.widget.RecyclerView.Adapter#onCreateViewHolder(android.view
* .ViewGroup, int) method only provides us the ViewGroup and a View Type, we must keep a mapping of
* (unique) view types in this merge adapter to each sub adapter, so we know which adapters' onCreateViewHolder method to call.
*
* The {@link MergeRecyclerAdapter.LocalAdapter} class
* is used to maintain this mapping, and the mViewTypeIndex field is used to provide a unique
* view type.
*
*
* -------------
* BUGS
* -------------
*
* There currently exists a bug when merging Views and Adapters. The RecyclerView throws the following error:
*
java.lang.IllegalArgumentException: Scrapped or attached views may not be recycled.
at android.support.v7.widget.RecyclerView$Recycler.recycleViewHolder(RecyclerView.java:2569)
at android.support.v7.widget.RecyclerView$Recycler.quickRecycleScrapView(RecyclerView.java:2610)
at android.support.v7.widget.RecyclerView$LayoutManager.removeAndRecycleScrapInt(RecyclerView.java:3992)
at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:1533)
at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:1600)
at android.view.View.layout(View.java:15273)
*
* I currently don't know what the fix is for this issue.
*
*/
public class MergeRecyclerAdapter<T extends RecyclerView.Adapter> extends RecyclerView
.Adapter {
private Context mContext;
protected ArrayList<LocalAdapter> mAdapters = new ArrayList<>();
protected ForwardingDataSetObserver observer = new ForwardingDataSetObserver();
private int mViewTypeIndex=0;
public MergeRecyclerAdapter() {
}
public MergeRecyclerAdapter(Context context) {
this.mContext = context;
}
/**
* A Mergeable adapter must implement both ListAdapter and SpinnerAdapter to be useful in lists and spinners.
*/
public class LocalAdapter {
public final T mAdapter;
public int mLocalPosition = 0;
public Map<Integer, Integer> mViewTypesMap = new HashMap<>();
public LocalAdapter(T adapter) {
mAdapter = adapter;
}
}
/** Append the given adapter to the list of merged adapters. */
public void addAdapter(T adapter) {
addAdapter(mAdapters.size(), adapter);
}
/** Add the given adapter to the list of merged adapters at the given index. */
public void addAdapter(int index, T adapter) {
mAdapters.add(index, new LocalAdapter(adapter));
adapter.registerAdapterDataObserver(observer);
notifyDataSetChanged();
}
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
* remove adapter
* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/** Remove the given adapter from the list of merged adapters. */
public void removeAdapter(T adapter) {
if (!mAdapters.contains(adapter)) return;
removeAdapter(mAdapters.indexOf(adapter));
}
/** Remove the adapter at the given index from the list of merged adapters. */
public void removeAdapter(int index) {
if (index < 0 || index >= mAdapters.size()) return;
LocalAdapter adapter = mAdapters.remove(index);
adapter.mAdapter.unregisterAdapterDataObserver(observer);
notifyDataSetChanged();
}
public int getSubAdapterCount() {
return mAdapters.size();
}
public T getSubAdapter(int index) {
return mAdapters.get(index).mAdapter;
}
/**
* Adds a new View to the roster of things to appear in
* the aggregate list.
*
* @param view
* Single view to add
*/
public void addView(View view) {
ArrayList<View> list=new ArrayList<View>(1);
list.add(view);
addViews(list);
}
/**
* Adds a list of views to the roster of things to appear
* in the aggregate list.
*
* @param views
* List of views to add
*/
public void addViews(List<View> views) {
addAdapter((T) new ViewsAdapter(mContext,views));
}
@Override public int getItemCount() {
int count = 0;
for (LocalAdapter adapter : mAdapters) {
count += adapter.mAdapter.getItemCount();
}
return count;
// TODO: cache counts until next onChanged
}
/**
* For a given merged position, find the corresponding Adapter and local position within that Adapter by iterating through Adapters and
* summing their counts until the merged position is found.
*
* @param position a merged (global) position
* @return the matching Adapter and local position, or null if not found
*/
public LocalAdapter getAdapterOffsetForItem(final int position) {
final int adapterCount = mAdapters.size();
int i = 0;
int count = 0;
while (i < adapterCount) {
LocalAdapter a = mAdapters.get(i);
int newCount = count + a.mAdapter.getItemCount();
if (position < newCount) {
a.mLocalPosition = position - count;
return a;
}
count = newCount;
i++;
}
return null;
}
@Override public long getItemId(int position) {
return position;
}
@Override public int getItemViewType(int position) {
LocalAdapter result = getAdapterOffsetForItem(position);
int localViewType = result.mAdapter.getItemViewType(result.mLocalPosition);
if (result.mViewTypesMap.containsValue(localViewType)) {
for (Map.Entry<Integer, Integer> entry : result.mViewTypesMap.entrySet()) {
if (entry.getValue() == localViewType) {
return entry.getKey();
}
}
}
mViewTypeIndex += 1;
result.mViewTypesMap.put(mViewTypeIndex, localViewType);
return mViewTypeIndex;
}
@Override public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
for (LocalAdapter adapter: mAdapters){
if (adapter.mViewTypesMap.containsKey(viewType))
return adapter.mAdapter.onCreateViewHolder(viewGroup,adapter.mViewTypesMap.get(viewType));
}
return null;
}
@Override public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {
LocalAdapter result = getAdapterOffsetForItem(position);
result.mAdapter.onBindViewHolder(viewHolder, result.mLocalPosition);
}
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
* forwarding data set observer
* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
private class ForwardingDataSetObserver extends RecyclerView.AdapterDataObserver {
@Override public void onChanged() {
notifyDataSetChanged();
}
@Override public void onItemRangeChanged(int positionStart, int itemCount) {
super.onItemRangeChanged(positionStart, itemCount);
notifyItemRangeChanged(positionStart, itemCount);
}
@Override public void onItemRangeInserted(int positionStart, int itemCount) {
super.onItemRangeInserted(positionStart, itemCount);
notifyItemRangeInserted(positionStart, itemCount);
}
@Override public void onItemRangeRemoved(int positionStart, int itemCount) {
super.onItemRangeRemoved(positionStart, itemCount);
notifyItemRangeRemoved(positionStart, itemCount);
}
}
/**
* ViewsAdapter, ported from CommonsWare SackOfViews adapter.
*/
public static class ViewsAdapter extends RecyclerView.Adapter {
private List<View> views=null;
private Context context;
/**
* Constructor creating an empty list of views, but with
* a specified count. Subclasses must override newView().
*/
public ViewsAdapter(Context context, int count) {
super();
this.context = context;
views=new ArrayList<>(count);
for (int i=0;i<count;i++) {
views.add(null);
}
}
/**
* Constructor wrapping a supplied list of views.
* Subclasses must override newView() if any of the elements
* in the list are null.
*/
public ViewsAdapter(Context context, List<View> views) {
super();
this.context = context;
this.views=views;
}
/**
* How many items are in the data set represented by this
* Adapter.
*/
@Override
public int getItemCount() {
return(views.size());
}
/**
* Get the type of View that will be created by getView()
* for the specified item.
* @param position Position of the item whose data we want
*/
@Override
public int getItemViewType(int position) {
return(position);
}
@Override public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
//view type is equal to the position in this adapter.
ViewsViewHolder holder = new ViewsViewHolder(views.get(viewType));
return holder;
}
@Override public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {
}
/**
* Get the row id associated with the specified position
* in the list.
* @param position Position of the item whose data we want
*/
@Override
public long getItemId(int position) {
return(position);
}
public boolean hasView(View v) {
return(views.contains(v));
}
/**
* Create a new View to go into the list at the specified
* position.
* @param position Position of the item whose data we want
* @param parent ViewGroup containing the returned View
*/
protected View newView(int position, ViewGroup parent) {
throw new RuntimeException("You must override newView()!");
}
}
public static class ViewsViewHolder extends RecyclerView.ViewHolder{
public ViewsViewHolder(View itemView) {
super(itemView);
}
}
}