| /* |
| * Copyright (C) 2016 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.android.deskclock; |
| |
| import android.app.Fragment; |
| import android.app.FragmentManager; |
| import android.app.FragmentTransaction; |
| import android.support.v13.app.FragmentCompat; |
| import android.support.v4.view.PagerAdapter; |
| import android.util.ArrayMap; |
| import android.view.View; |
| import android.view.ViewGroup; |
| |
| import com.android.deskclock.uidata.UiDataModel; |
| |
| import java.util.Map; |
| |
| /** |
| * This adapter produces the DeskClockFragments that are the content of the DeskClock tabs. The |
| * adapter presents the tabs in LTR and RTL order depending on the text layout direction for the |
| * current locale. To prevent issues when switching between LTR and RTL, fragments are registered |
| * with the manager using position-independent tags, which is an important departure from |
| * FragmentPagerAdapter. |
| */ |
| final class FragmentTabPagerAdapter extends PagerAdapter { |
| |
| private final DeskClock mDeskClock; |
| |
| /** The manager into which fragments are added. */ |
| private final FragmentManager mFragmentManager; |
| |
| /** A fragment cache that can be accessed before {@link #instantiateItem} is called. */ |
| private final Map<UiDataModel.Tab, DeskClockFragment> mFragmentCache; |
| |
| /** The active fragment transaction if one exists. */ |
| private FragmentTransaction mCurrentTransaction; |
| |
| /** The current fragment displayed to the user. */ |
| private Fragment mCurrentPrimaryItem; |
| |
| FragmentTabPagerAdapter(DeskClock deskClock) { |
| mDeskClock = deskClock; |
| mFragmentCache = new ArrayMap<>(getCount()); |
| mFragmentManager = deskClock.getFragmentManager(); |
| } |
| |
| @Override |
| public int getCount() { |
| return UiDataModel.getUiDataModel().getTabCount(); |
| } |
| |
| /** |
| * @param position the left-to-right index of the fragment to be returned |
| * @return the fragment displayed at the given {@code position} |
| */ |
| DeskClockFragment getDeskClockFragment(int position) { |
| // Fetch the tab the UiDataModel reports for the position. |
| final UiDataModel.Tab tab = UiDataModel.getUiDataModel().getTabAt(position); |
| |
| // First check the local cache for the fragment. |
| DeskClockFragment fragment = mFragmentCache.get(tab); |
| if (fragment != null) { |
| return fragment; |
| } |
| |
| // Next check the fragment manager; relevant when app is rebuilt after locale changes |
| // because this adapter will be new and mFragmentCache will be empty, but the fragment |
| // manager will retain the Fragments built on original application launch. |
| fragment = (DeskClockFragment) mFragmentManager.findFragmentByTag(tab.name()); |
| if (fragment != null) { |
| fragment.setFabContainer(mDeskClock); |
| mFragmentCache.put(tab, fragment); |
| return fragment; |
| } |
| |
| // Otherwise, build the fragment from scratch. |
| final String fragmentClassName = tab.getFragmentClassName(); |
| fragment = (DeskClockFragment) Fragment.instantiate(mDeskClock, fragmentClassName); |
| fragment.setFabContainer(mDeskClock); |
| mFragmentCache.put(tab, fragment); |
| return fragment; |
| } |
| |
| @Override |
| public void startUpdate(ViewGroup container) { |
| if (container.getId() == View.NO_ID) { |
| throw new IllegalStateException("ViewPager with adapter " + this + " has no id"); |
| } |
| } |
| |
| @Override |
| public Object instantiateItem(ViewGroup container, int position) { |
| if (mCurrentTransaction == null) { |
| mCurrentTransaction = mFragmentManager.beginTransaction(); |
| } |
| |
| // Use the fragment located in the fragment manager if one exists. |
| final UiDataModel.Tab tab = UiDataModel.getUiDataModel().getTabAt(position); |
| Fragment fragment = mFragmentManager.findFragmentByTag(tab.name()); |
| if (fragment != null) { |
| mCurrentTransaction.attach(fragment); |
| } else { |
| fragment = getDeskClockFragment(position); |
| mCurrentTransaction.add(container.getId(), fragment, tab.name()); |
| } |
| |
| if (fragment != mCurrentPrimaryItem) { |
| FragmentCompat.setMenuVisibility(fragment, false); |
| FragmentCompat.setUserVisibleHint(fragment, false); |
| } |
| |
| return fragment; |
| } |
| |
| @Override |
| public void destroyItem(ViewGroup container, int position, Object object) { |
| if (mCurrentTransaction == null) { |
| mCurrentTransaction = mFragmentManager.beginTransaction(); |
| } |
| final DeskClockFragment fragment = (DeskClockFragment) object; |
| fragment.setFabContainer(null); |
| mCurrentTransaction.detach(fragment); |
| } |
| |
| @Override |
| public void setPrimaryItem(ViewGroup container, int position, Object object) { |
| final Fragment fragment = (Fragment) object; |
| if (fragment != mCurrentPrimaryItem) { |
| if (mCurrentPrimaryItem != null) { |
| FragmentCompat.setMenuVisibility(mCurrentPrimaryItem, false); |
| FragmentCompat.setUserVisibleHint(mCurrentPrimaryItem, false); |
| } |
| if (fragment != null) { |
| FragmentCompat.setMenuVisibility(fragment, true); |
| FragmentCompat.setUserVisibleHint(fragment, true); |
| } |
| mCurrentPrimaryItem = fragment; |
| } |
| } |
| |
| @Override |
| public void finishUpdate(ViewGroup container) { |
| if (mCurrentTransaction != null) { |
| mCurrentTransaction.commitAllowingStateLoss(); |
| mCurrentTransaction = null; |
| mFragmentManager.executePendingTransactions(); |
| } |
| } |
| |
| @Override |
| public boolean isViewFromObject(View view, Object object) { |
| return ((Fragment) object).getView() == view; |
| } |
| } |