/*
* 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 org.aisen.android.ui.fragment.adapter;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.os.Parcelable;
import android.support.v4.view.PagerAdapter;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import org.aisen.android.ui.fragment.APagingFragment;
/**
* Implementation of {@link PagerAdapter} that
* represents each page as a {@link Fragment} that is persistently kept in the
* fragment manager as long as the user can return to the page.
*
* <p>
* This version of the pager is best for use when there are a handful of
* typically more static fragments to be paged through, such as a set of tabs.
* The fragment of each page the user visits will be kept in memory, though its
* view hierarchy may be destroyed when not visible. This can result in using a
* significant amount of memory since fragment instances can hold on to an
* arbitrary amount of state. For larger sets of pages, consider
* {@link android.support.v4.app.FragmentStatePagerAdapter}.
*
* <p>
* When using FragmentPagerAdapter the host ViewPager must have a valid ID set.
* </p>
*
* <p>
* Subclasses only need to implement {@link #getItem(int)} and
* {@link #getCount()} to have a working adapter.
*
* <p>
* Here is an example implementation of a pager containing fragments of lists:
*
* {@sample
* development/samples/Support4Demos/src/com/example/android/supportv4/app/
* FragmentPagerSupport.java complete}
*
* <p>
* The <code>R.layout.fragment_pager</code> resource of the top-level fragment
* is:
*
* {@sample development/samples/Support4Demos/res/layout/fragment_pager.xml
* complete}
*
* <p>
* The <code>R.layout.fragment_pager_list</code> resource containing each
* individual fragment's layout is:
*
* {@sample development/samples/Support4Demos/res/layout/fragment_pager_list.xml
* complete}
*/
public abstract class FragmentPagerAdapter extends PagerAdapter {
private static final String TAG = "FragmentPagerAdapter";
private static final boolean DEBUG = false;
protected final FragmentManager mFragmentManager;
protected FragmentTransaction mCurTransaction = null;
private Fragment mCurrentPrimaryItem = null;
public FragmentPagerAdapter(FragmentManager fm) {
mFragmentManager = fm;
}
/**
* Return the Fragment associated with a specified position.
*/
public abstract Fragment getItem(int position);
@Override
public void startUpdate(ViewGroup container) {
}
@Override
public Object instantiateItem(ViewGroup container, int position) {
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
final long itemId = getItemId(position);
// Do we already have this fragment?
String name = makeFragmentName(position);
Fragment fragment = mFragmentManager.findFragmentByTag(name);
if (fragment != null) {
if (DEBUG)
Log.v(TAG, "Attaching item #" + itemId + ": f=" + fragment);
// mCurTransaction.attach(fragment);
freshUI(position, fragment);
} else {
fragment = getItem(position);
if (DEBUG)
Log.v(TAG, "Adding item #" + itemId + ": f=" + fragment);
mCurTransaction.add(container.getId(), fragment, makeFragmentName(position));
}
if (fragment != mCurrentPrimaryItem) {
fragment.setMenuVisibility(false);
}
if (fragment instanceof FragmentPagerChangeListener)
((FragmentPagerChangeListener) fragment).instantiate(makeFragmentName(position));
return fragment;
}
protected void freshUI(int position, Fragment fragment) {
if (fragment instanceof APagingFragment)
((APagingFragment) fragment).refreshUI();
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
if (DEBUG)
Log.v(TAG, "Detaching item #" + getItemId(position) + ": f=" + object + " v=" + ((Fragment) object).getView());
// mCurTransaction.detach((Fragment) object);
if (object instanceof APagingFragment)
((APagingFragment) object).releaseImageViewByIds();
if (object instanceof FragmentPagerChangeListener)
((FragmentPagerChangeListener) object).destroy(makeFragmentName(position));
}
@Override
public void setPrimaryItem(ViewGroup container, int position, Object object) {
Fragment fragment = (Fragment) object;
if (fragment != mCurrentPrimaryItem) {
if (mCurrentPrimaryItem != null) {
mCurrentPrimaryItem.setMenuVisibility(false);
}
if (fragment != null) {
fragment.setMenuVisibility(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() {
return null;
}
@Override
public void restoreState(Parcelable state, ClassLoader loader) {
}
/**
* Return a unique identifier for the item at the given position.
*
* <p>
* The default implementation returns the given position. Subclasses should
* override this method if the positions of items can change.
* </p>
*
* @param position
* Position within this adapter
* @return Unique identifier for the item at position
*/
public long getItemId(int position) {
return position;
}
protected abstract String makeFragmentName(int position);
}