1 /* 2 * Copyright (C) 2012 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.mail.utils; 18 19 import android.app.Fragment; 20 import android.app.FragmentManager; 21 import android.app.FragmentTransaction; 22 import android.os.Bundle; 23 import android.os.Parcelable; 24 import android.support.v13.app.FragmentCompat; 25 import android.support.v13.app.FragmentStatePagerAdapter; 26 import android.support.v4.util.SparseArrayCompat; 27 import android.support.v4.view.PagerAdapter; 28 import android.view.View; 29 import android.view.ViewGroup; 30 31 import java.util.ArrayList; 32 33 /** 34 * Forked from support lib's {@link FragmentStatePagerAdapter}, with some minor 35 * changes that couldn't be accomplished through subclassing: 36 * <ul> 37 * <li>optionally disable stateful behavior when paging (controlled by {@link #mEnableSavedStates}), 38 * for situations where state save/restore when paging is unnecessary</li> 39 * <li>override-able {@link #setItemVisible(Fragment, boolean)} method for subclasses to 40 * add supplemental handling of visibility hints manually on pre-v15 devices</li> 41 * <li>add support to handle data set changes that cause item positions to change</li> 42 * <li>allow read access to existing Fragments by index ({@link #getFragmentAt(int)})</li> 43 * </ul> 44 */ 45 public abstract class FragmentStatePagerAdapter2 extends PagerAdapter { 46 private static final String TAG = "FSPA"; // the support lib's tag is too long and crashes :) 47 private static final boolean DEBUG = false; 48 49 private final FragmentManager mFragmentManager; 50 private FragmentTransaction mCurTransaction = null; 51 52 private ArrayList<Fragment.SavedState> mSavedState = new ArrayList<Fragment.SavedState>(); 53 private SparseArrayCompat<Fragment> mFragments = new SparseArrayCompat<Fragment>(); 54 private Fragment mCurrentPrimaryItem = null; 55 56 private boolean mEnableSavedStates; 57 58 public FragmentStatePagerAdapter2(FragmentManager fm) { 59 this(fm, true); 60 } 61 62 public FragmentStatePagerAdapter2(FragmentManager fm, boolean enableSavedStates) { 63 mFragmentManager = fm; 64 mEnableSavedStates = enableSavedStates; 65 } 66 67 /** 68 * Return the Fragment associated with a specified position. 69 */ 70 public abstract Fragment getItem(int position); 71 72 @Override 73 public void startUpdate(ViewGroup container) { 74 } 75 76 @Override 77 public Object instantiateItem(ViewGroup container, int position) { 78 // If we already have this item instantiated, there is nothing 79 // to do. This can happen when we are restoring the entire pager 80 // from its saved state, where the fragment manager has already 81 // taken care of restoring the fragments we previously had instantiated. 82 final Fragment existing = mFragments.get(position); 83 if (existing != null) { 84 return existing; 85 } 86 87 if (mCurTransaction == null) { 88 mCurTransaction = mFragmentManager.beginTransaction(); 89 } 90 91 Fragment fragment = getItem(position); 92 if (DEBUG) LogUtils.v(TAG, "Adding item #" + position + ": f=" + fragment); 93 if (mEnableSavedStates && mSavedState.size() > position) { 94 Fragment.SavedState fss = mSavedState.get(position); 95 if (fss != null) { 96 fragment.setInitialSavedState(fss); 97 } 98 } 99 if (fragment != mCurrentPrimaryItem) { 100 setItemVisible(fragment, false); 101 } 102 mFragments.put(position, fragment); 103 mCurTransaction.add(container.getId(), fragment); 104 105 return fragment; 106 } 107 108 @Override 109 public void destroyItem(ViewGroup container, int position, Object object) { 110 Fragment fragment = (Fragment)object; 111 112 if (mCurTransaction == null) { 113 mCurTransaction = mFragmentManager.beginTransaction(); 114 } 115 if (DEBUG) LogUtils.v(TAG, "Removing item #" + position + ": f=" + object 116 + " v=" + ((Fragment)object).getView()); 117 if (mEnableSavedStates) { 118 while (mSavedState.size() <= position) { 119 mSavedState.add(null); 120 } 121 mSavedState.set(position, mFragmentManager.saveFragmentInstanceState(fragment)); 122 } 123 mFragments.delete(position); 124 125 mCurTransaction.remove(fragment); 126 } 127 128 @Override 129 public void setPrimaryItem(ViewGroup container, int position, Object object) { 130 Fragment fragment = (Fragment)object; 131 if (fragment != mCurrentPrimaryItem) { 132 if (mCurrentPrimaryItem != null) { 133 setItemVisible(mCurrentPrimaryItem, false); 134 } 135 if (fragment != null) { 136 setItemVisible(fragment, true); 137 } 138 mCurrentPrimaryItem = fragment; 139 } 140 } 141 142 @Override 143 public void finishUpdate(ViewGroup container) { 144 if (mCurTransaction != null) { 145 mCurTransaction.commitAllowingStateLoss(); 146 mCurTransaction = null; 147 mFragmentManager.executePendingTransactions(); 148 } 149 } 150 151 @Override 152 public boolean isViewFromObject(View view, Object object) { 153 return ((Fragment)object).getView() == view; 154 } 155 156 @Override 157 public Parcelable saveState() { 158 Bundle state = null; 159 if (mEnableSavedStates && mSavedState.size() > 0) { 160 state = new Bundle(); 161 Fragment.SavedState[] fss = new Fragment.SavedState[mSavedState.size()]; 162 mSavedState.toArray(fss); 163 state.putParcelableArray("states", fss); 164 } 165 for (int i=0; i<mFragments.size(); i++) { 166 final int pos = mFragments.keyAt(i); 167 final Fragment f = mFragments.valueAt(i); 168 if (state == null) { 169 state = new Bundle(); 170 } 171 String key = "f" + pos; 172 mFragmentManager.putFragment(state, key, f); 173 } 174 return state; 175 } 176 177 @Override 178 public void restoreState(Parcelable state, ClassLoader loader) { 179 if (state != null) { 180 Bundle bundle = (Bundle)state; 181 bundle.setClassLoader(loader); 182 mFragments.clear(); 183 if (mEnableSavedStates) { 184 Parcelable[] fss = bundle.getParcelableArray("states"); 185 mSavedState.clear(); 186 if (fss != null) { 187 for (int i=0; i<fss.length; i++) { 188 mSavedState.add((Fragment.SavedState)fss[i]); 189 } 190 } 191 } 192 Iterable<String> keys = bundle.keySet(); 193 for (String key: keys) { 194 if (key.startsWith("f")) { 195 int index = Integer.parseInt(key.substring(1)); 196 Fragment f = mFragmentManager.getFragment(bundle, key); 197 if (f != null) { 198 setItemVisible(f, false); 199 mFragments.put(index, f); 200 } else { 201 LogUtils.w(TAG, "Bad fragment at key " + key); 202 } 203 } 204 } 205 } 206 } 207 208 public void setItemVisible(Fragment item, boolean visible) { 209 FragmentCompat.setMenuVisibility(item, visible); 210 FragmentCompat.setUserVisibleHint(item, visible); 211 } 212 213 @Override 214 public void notifyDataSetChanged() { 215 // update positions in mFragments 216 SparseArrayCompat<Fragment> newFragments = 217 new SparseArrayCompat<Fragment>(mFragments.size()); 218 for (int i=0; i<mFragments.size(); i++) { 219 final int oldPos = mFragments.keyAt(i); 220 final Fragment f = mFragments.valueAt(i); 221 final int newPos = getItemPosition(f); 222 223 if (newPos != POSITION_NONE) { 224 final int pos = (newPos >= 0) ? newPos : oldPos; 225 newFragments.put(pos, f); 226 } 227 } 228 mFragments = newFragments; 229 230 super.notifyDataSetChanged(); 231 } 232 233 public Fragment getFragmentAt(int position) { 234 return mFragments.get(position); 235 } 236 } 237
