/
RecyclerPagerAdapter.java
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/
RecyclerPagerAdapter.java
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/*
* Copyright 2015 "Henry Tao <hi@henrytao.me>"
*
* 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 me.henrytao.recyclerpageradapter;
import android.os.Bundle;
import android.os.Parcelable;
import android.support.v4.view.PagerAdapter;
import android.util.SparseArray;
import android.view.View;
import android.view.ViewGroup;
import java.util.ArrayList;
import java.util.List;
/**
* Created by henrytao on 11/13/15.
*/
public abstract class RecyclerPagerAdapter<VH extends RecyclerPagerAdapter.ViewHolder> extends PagerAdapter {
public abstract int getItemCount();
public abstract void onBindViewHolder(VH holder, int position);
public abstract VH onCreateViewHolder(ViewGroup parent, int viewType);
private static final String STATE = RecyclerPagerAdapter.class.getSimpleName();
private static final String TAG = RecyclerPagerAdapter.class.getSimpleName();
public static boolean DEBUG = false;
private Logger mLogger;
private SparseArray<RecycleCache> mRecycleTypeCaches = new SparseArray<>();
private SparseArray<Parcelable> mSavedStates = new SparseArray<>();
public RecyclerPagerAdapter() {
mLogger = Logger.newInstance(TAG, DEBUG ? Logger.LogLevel.VERBOSE : Logger.LogLevel.NONE);
}
@Override
public void destroyItem(ViewGroup parent, int position, Object object) {
mLogger.d("destroyItem | position: %d | instanceOfViewHolder: %b", position, object instanceof ViewHolder);
if (object instanceof ViewHolder) {
((ViewHolder) object).detach(parent);
}
}
@Override
public int getCount() {
return getItemCount();
}
@Override
public int getItemPosition(Object object) {
mLogger.d("getItemPosition | instanceOfViewHolder: %b | currentPosition: %d | isAttached: %b",
object instanceof ViewHolder,
object instanceof ViewHolder ? ((ViewHolder) object).mPosition : -1,
object instanceof ViewHolder && ((ViewHolder) object).mIsAttached);
return POSITION_NONE;
}
@SuppressWarnings("unchecked")
@Override
public Object instantiateItem(ViewGroup parent, int position) {
int viewType = getItemViewType(position);
if (mRecycleTypeCaches.get(viewType) == null) {
mRecycleTypeCaches.put(viewType, new RecycleCache(this));
}
ViewHolder viewHolder = mRecycleTypeCaches.get(viewType).getFreeViewHolder(parent, viewType);
viewHolder.attach(parent, position);
onBindViewHolder((VH) viewHolder, position);
mLogger.d("instantiateItem | position: %d | viewType: %d | cacheCount: %d",
position, viewType, mRecycleTypeCaches.get(viewType).mCaches.size());
viewHolder.onRestoreInstanceState(mSavedStates.get(getItemId(position)));
return viewHolder;
}
@Override
public boolean isViewFromObject(View view, Object object) {
return object instanceof ViewHolder && ((ViewHolder) object).itemView == view;
}
@Override
public void notifyDataSetChanged() {
mLogger.d("notifyDataSetChanged");
super.notifyDataSetChanged();
for (ViewHolder viewHolder : getAttachedViewHolders()) {
onNotifyItemChanged(viewHolder);
}
}
@Override
public void restoreState(Parcelable state, ClassLoader loader) {
if (state instanceof Bundle) {
Bundle bundle = (Bundle) state;
bundle.setClassLoader(loader);
SparseArray<Parcelable> ss = bundle.containsKey(STATE) ? bundle.getSparseParcelableArray(STATE) : null;
mSavedStates = ss != null ? ss : new SparseArray<Parcelable>();
}
super.restoreState(state, loader);
}
@Override
public Parcelable saveState() {
Bundle bundle = new Bundle();
for (ViewHolder viewHolder : getAttachedViewHolders()) {
mSavedStates.put(getItemId(viewHolder.mPosition), viewHolder.onSaveInstanceState());
}
bundle.putSparseParcelableArray(STATE, mSavedStates);
return bundle;
}
public int getItemId(int position) {
return position;
}
public int getItemViewType(int position) {
return 0;
}
protected void onNotifyItemChanged(ViewHolder viewHolder) {
}
private List<ViewHolder> getAttachedViewHolders() {
List<ViewHolder> attachedViewHolders = new ArrayList<>();
int n = mRecycleTypeCaches.size();
for (int i = 0; i < n; i++) {
for (ViewHolder viewHolder : mRecycleTypeCaches.get(mRecycleTypeCaches.keyAt(i)).mCaches) {
if (viewHolder.mIsAttached) {
attachedViewHolders.add(viewHolder);
}
}
}
return attachedViewHolders;
}
private static class RecycleCache {
private final RecyclerPagerAdapter mAdapter;
private final List<ViewHolder> mCaches;
RecycleCache(RecyclerPagerAdapter adapter) {
mAdapter = adapter;
mCaches = new ArrayList<>();
}
ViewHolder getFreeViewHolder(ViewGroup parent, int viewType) {
int i = 0;
ViewHolder viewHolder;
for (int n = mCaches.size(); i < n; i++) {
viewHolder = mCaches.get(i);
if (!viewHolder.mIsAttached) {
return viewHolder;
}
}
viewHolder = mAdapter.onCreateViewHolder(parent, viewType);
mCaches.add(viewHolder);
return viewHolder;
}
}
public static abstract class ViewHolder {
private static final String STATE = ViewHolder.class.getSimpleName();
public final View itemView;
private boolean mIsAttached;
private int mPosition;
public ViewHolder(View itemView) {
if (itemView == null) {
throw new IllegalArgumentException("itemView should not be null");
}
this.itemView = itemView;
}
private void attach(ViewGroup parent, int position) {
mIsAttached = true;
mPosition = position;
parent.addView(itemView);
}
private void detach(ViewGroup parent) {
parent.removeView(itemView);
mIsAttached = false;
}
private void onRestoreInstanceState(Parcelable state) {
if (state instanceof Bundle) {
Bundle bundle = (Bundle) state;
SparseArray<Parcelable> ss = bundle.containsKey(STATE) ? bundle.getSparseParcelableArray(STATE) : null;
if (ss != null) {
itemView.restoreHierarchyState(ss);
}
}
}
private Parcelable onSaveInstanceState() {
SparseArray<Parcelable> state = new SparseArray<>();
itemView.saveHierarchyState(state);
Bundle bundle = new Bundle();
bundle.putSparseParcelableArray(STATE, state);
return bundle;
}
}
}