1 /* 2 * Copyright (C) 2020 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.deskclock 18 19 import android.util.ArrayMap 20 import android.view.View 21 import android.view.ViewGroup 22 import androidx.fragment.app.Fragment 23 import androidx.fragment.app.FragmentManager 24 import androidx.fragment.app.FragmentTransaction 25 import androidx.viewpager.widget.PagerAdapter 26 27 import com.android.deskclock.uidata.UiDataModel 28 29 /** 30 * This adapter produces the DeskClockFragments that are the content of the DeskClock tabs. The 31 * adapter presents the tabs in LTR and RTL order depending on the text layout direction for the 32 * current locale. To prevent issues when switching between LTR and RTL, fragments are registered 33 * with the manager using position-independent tags, which is an important departure from 34 * FragmentPagerAdapter. 35 */ 36 internal class FragmentTabPagerAdapter(private val mDeskClock: DeskClock) : PagerAdapter() { 37 38 /** The manager into which fragments are added. */ 39 private val mFragmentManager: FragmentManager = mDeskClock.supportFragmentManager 40 41 /** A fragment cache that can be accessed before [.instantiateItem] is called. */ 42 private val mFragmentCache: MutableMap<UiDataModel.Tab, DeskClockFragment?> = 43 ArrayMap(getCount()) 44 45 /** The active fragment transaction if one exists. */ 46 private var mCurrentTransaction: FragmentTransaction? = null 47 48 /** The current fragment displayed to the user. */ 49 private var mCurrentPrimaryItem: Fragment? = null 50 getCountnull51 override fun getCount(): Int = UiDataModel.uiDataModel.tabCount 52 53 /** 54 * @param position the left-to-right index of the fragment to be returned 55 * @return the fragment displayed at the given `position` 56 */ 57 fun getDeskClockFragment(position: Int): DeskClockFragment { 58 // Fetch the tab the UiDataModel reports for the position. 59 val tab: UiDataModel.Tab = UiDataModel.uiDataModel.getTabAt(position) 60 61 // First check the local cache for the fragment. 62 var fragment = mFragmentCache[tab] 63 if (fragment != null) { 64 return fragment 65 } 66 67 // Next check the fragment manager; relevant when app is rebuilt after locale changes 68 // because this adapter will be new and mFragmentCache will be empty, but the fragment 69 // manager will retain the Fragments built on original application launch. 70 fragment = mFragmentManager.findFragmentByTag(tab.name) as DeskClockFragment? 71 if (fragment != null) { 72 fragment.setFabContainer(mDeskClock) 73 mFragmentCache[tab] = fragment 74 return fragment 75 } 76 77 // Otherwise, build the fragment from scratch. 78 val fragmentClassName: String = tab.fragmentClassName 79 fragment = Fragment.instantiate(mDeskClock, fragmentClassName) as DeskClockFragment 80 fragment.setFabContainer(mDeskClock) 81 mFragmentCache[tab] = fragment 82 return fragment 83 } 84 startUpdatenull85 override fun startUpdate(container: ViewGroup) { 86 check(container.id != View.NO_ID) { "ViewPager with adapter $this has no id" } 87 } 88 instantiateItemnull89 override fun instantiateItem(container: ViewGroup, position: Int): Any { 90 if (mCurrentTransaction == null) { 91 mCurrentTransaction = mFragmentManager.beginTransaction() 92 } 93 94 // Use the fragment located in the fragment manager if one exists. 95 val tab: UiDataModel.Tab = UiDataModel.uiDataModel.getTabAt(position) 96 var fragment = mFragmentManager.findFragmentByTag(tab.name) 97 if (fragment != null) { 98 mCurrentTransaction!!.attach(fragment) 99 } else { 100 fragment = getDeskClockFragment(position) 101 mCurrentTransaction!!.add(container.id, fragment, tab.name) 102 } 103 104 if (fragment !== mCurrentPrimaryItem) { 105 fragment.setMenuVisibility(false) 106 fragment.setUserVisibleHint(false) 107 } 108 109 return fragment 110 } 111 destroyItemnull112 override fun destroyItem(container: ViewGroup, position: Int, any: Any) { 113 if (mCurrentTransaction == null) { 114 mCurrentTransaction = mFragmentManager.beginTransaction() 115 } 116 val fragment = any as DeskClockFragment 117 fragment.setFabContainer(null) 118 mCurrentTransaction!!.detach(fragment) 119 } 120 setPrimaryItemnull121 override fun setPrimaryItem(container: ViewGroup, position: Int, any: Any) { 122 val fragment = any as Fragment 123 if (fragment !== mCurrentPrimaryItem) { 124 mCurrentPrimaryItem?.let { 125 it.setMenuVisibility(false) 126 it.setUserVisibleHint(false) 127 } 128 fragment.setMenuVisibility(true) 129 fragment.setUserVisibleHint(true) 130 mCurrentPrimaryItem = fragment 131 } 132 } 133 finishUpdatenull134 override fun finishUpdate(container: ViewGroup) { 135 if (mCurrentTransaction != null) { 136 mCurrentTransaction!!.commitAllowingStateLoss() 137 mCurrentTransaction = null 138 mFragmentManager.executePendingTransactions() 139 } 140 } 141 isViewFromObjectnull142 override fun isViewFromObject(view: View, any: Any): Boolean = (any as Fragment).view === view 143 }