/*
* Copyright (C) 2011 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.sbrukhanda.fragmentviewpager.adapters;
import android.os.Bundle;
import android.os.Parcelable;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.view.PagerAdapter;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import java.util.ArrayList;
/**
* A modified copy of the {@link android.support.v4.app.FragmentStatePagerAdapter}, which retains its
* original behaviour, but incorporates some additions and changes to its methods. <p />
*
* Firstly, method {@link android.support.v4.app.FragmentStatePagerAdapter#getItem(int)} was replaced
* with a more appropriately named {@link #instantiateFragment(int)} method. <p />
*
* Secondly, method {@link #getFragment(int)} was added in order to allow access to the underlying
* mechanism of stored {@code Fragment}s. <p />
*
* <b>Note:</b> The Support-v4 v23.1.1 {@link android.support.v4.app.FragmentStatePagerAdapter}'s
* source was used as a base.
*
* @author Serhiy Brukhanda <http://lnkd.in/dMuBjh8>
*/
public abstract class FragmentStatePagerAdapter extends PagerAdapter
{
// =============================================================================================
// Constants
// =============================================================================================
private static final String TAG = FragmentStatePagerAdapter.class.getSimpleName();
private static final boolean DEBUG = true;
// =============================================================================================
// Fields
// =============================================================================================
private final FragmentManager mFragmentManager;
private FragmentTransaction mCurTransaction = null;
private ArrayList<Fragment.SavedState> mSavedState = new ArrayList<Fragment.SavedState>();
private ArrayList<Fragment> mFragments = new ArrayList<Fragment>();
private Fragment mCurrentPrimaryItem = null;
// =============================================================================================
// Constructors & Methods
// =============================================================================================
// *********************************************************************************************
public FragmentStatePagerAdapter(FragmentManager fm) {
mFragmentManager = fm;
}
// *********************************************************************************************
@Override
public void startUpdate(ViewGroup container) {
// Nothing needed
}
/**
* Returns the {@code Fragment} associated with the specified position.
*
* @param position The position of the {@code Fragment} to fetch.
* @return The {@code Fragment} associated with the specified position if such exists, else
* {@code null}.
*/
public Fragment getFragment(int position) {
return ((mFragments.size() > position) ? mFragments.get(position) : null);
}
/**
* Create the {@code Fragment} for the specified position.
*
* @param position The position of the {@code Fragment} to create.
* @return The newly created {@code Fragment}.
*/
public abstract Fragment instantiateFragment(int position);
// *********************************************************************************************
@Override
public Object instantiateItem(ViewGroup container, int position) {
// -----------------------------------------------------------------------------------------
// If we already have this item instantiated, there is nothing to do. This can happen when
// we are restoring the entire pager from its saved state, where the fragment manager has
// already taken care of restoring the fragments we previously had instantiated.
// -----------------------------------------------------------------------------------------
Fragment existingFragment = getFragment(position);
if (existingFragment != null) {
return existingFragment;
}
// -----------------------------------------------------------------------------------------
// Else, continue with normal flow.
// -----------------------------------------------------------------------------------------
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
Fragment fragment = instantiateFragment(position);
if (DEBUG) Log.v(TAG, "Adding item #" + position + ": f=" + fragment);
if (mSavedState.size() > position) {
Fragment.SavedState fss = mSavedState.get(position);
if (fss != null) {
fragment.setInitialSavedState(fss);
}
}
while (mFragments.size() <= position) {
mFragments.add(null);
}
fragment.setMenuVisibility(false);
fragment.setUserVisibleHint(false);
mFragments.set(position, fragment);
mCurTransaction.add(container.getId(), fragment);
return fragment;
}
// *********************************************************************************************
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
Fragment fragment = (Fragment)object;
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
if (DEBUG) Log.v(TAG, "Removing item #" + position + ": f=" + object
+ " v=" + ((Fragment)object).getView());
while (mSavedState.size() <= position) {
mSavedState.add(null);
}
mSavedState.set(position, mFragmentManager.saveFragmentInstanceState(fragment));
mFragments.set(position, null);
mCurTransaction.remove(fragment);
}
// *********************************************************************************************
@Override
public void setPrimaryItem(ViewGroup container, int position, Object object) {
Fragment fragment = (Fragment)object;
if (fragment != mCurrentPrimaryItem) {
if (mCurrentPrimaryItem != null) {
mCurrentPrimaryItem.setMenuVisibility(false);
mCurrentPrimaryItem.setUserVisibleHint(false);
}
if (fragment != null) {
fragment.setMenuVisibility(true);
fragment.setUserVisibleHint(true);
}
mCurrentPrimaryItem = fragment;
}
}
// *********************************************************************************************
@Override
public void finishUpdate(ViewGroup container) {
if (mCurTransaction != null) {
mCurTransaction.commitAllowingStateLoss();
mCurTransaction = null;
mFragmentManager.executePendingTransactions();
}
}
// *********************************************************************************************
@Override
public boolean isViewFromObject(View view, Object object) {
return ((Fragment)object).getView() == view;
}
// *********************************************************************************************
@Override
public Parcelable saveState() {
Bundle state = null;
if (mSavedState.size() > 0) {
state = new Bundle();
Fragment.SavedState[] fss = new Fragment.SavedState[mSavedState.size()];
mSavedState.toArray(fss);
state.putParcelableArray("states", fss);
}
for (int i=0; i<mFragments.size(); i++) {
Fragment f = mFragments.get(i);
if (f != null && f.isAdded()) {
if (state == null) {
state = new Bundle();
}
String key = "f" + i;
mFragmentManager.putFragment(state, key, f);
}
}
return state;
}
// *********************************************************************************************
@Override
public void restoreState(Parcelable state, ClassLoader loader) {
if (state != null) {
Bundle bundle = (Bundle)state;
bundle.setClassLoader(loader);
Parcelable[] fss = bundle.getParcelableArray("states");
mSavedState.clear();
mFragments.clear();
if (fss != null) {
for (int i=0; i<fss.length; i++) {
mSavedState.add((Fragment.SavedState)fss[i]);
}
}
Iterable<String> keys = bundle.keySet();
for (String key: keys) {
if (key.startsWith("f")) {
int index = Integer.parseInt(key.substring(1));
Fragment f = mFragmentManager.getFragment(bundle, key);
if (f != null) {
while (mFragments.size() <= index) {
mFragments.add(null);
}
f.setMenuVisibility(false);
mFragments.set(index, f);
} else {
Log.w(TAG, "Bad fragment at key " + key);
}
}
}
}
}
}
