From 737a2d4d723df9ba0e080cdb3fdff3e0749c5c60 Mon Sep 17 00:00:00 2001
From: gedoor <gekunfei@live.com>
Date: Mon, 10 May 2021 15:36:40 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BF=AE=E6=94=B9=E8=BF=87=E6=9C=9F=E6=96=B9?=
 =?UTF-8?q?=E6=B3=95viewPager?=
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---
 .../ui/main/bookshelf/BookshelfFragment.kt    | 37 +++++++++----------
 .../main/res/layout/fragment_bookshelf.xml    |  2 +-
 2 files changed, 18 insertions(+), 21 deletions(-)

diff --git a/app/src/main/java/io/legado/app/ui/main/bookshelf/BookshelfFragment.kt b/app/src/main/java/io/legado/app/ui/main/bookshelf/BookshelfFragment.kt
index 090edd420..116261ded 100644
--- a/app/src/main/java/io/legado/app/ui/main/bookshelf/BookshelfFragment.kt
+++ b/app/src/main/java/io/legado/app/ui/main/bookshelf/BookshelfFragment.kt
@@ -5,11 +5,14 @@ import android.os.Bundle
 import android.view.Menu
 import android.view.MenuItem
 import android.view.View
-import android.view.ViewGroup
 import androidx.appcompat.widget.SearchView
-import androidx.fragment.app.*
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.activityViewModels
+import androidx.fragment.app.viewModels
 import androidx.lifecycle.LiveData
+import androidx.viewpager2.adapter.FragmentStateAdapter
 import com.google.android.material.tabs.TabLayout
+import com.google.android.material.tabs.TabLayoutMediator
 import io.legado.app.R
 import io.legado.app.base.VMBaseFragment
 import io.legado.app.constant.AppConst
@@ -44,7 +47,7 @@ class BookshelfFragment : VMBaseFragment<BookshelfViewModel>(R.layout.fragment_b
     private val binding by viewBinding(FragmentBookshelfBinding::bind)
     override val viewModel: BookshelfViewModel by viewModels()
     private val activityViewModel: MainViewModel by activityViewModels()
-    private lateinit var adapter: FragmentStatePagerAdapter
+    private lateinit var adapter: FragmentStateAdapter
     private lateinit var tabLayout: TabLayout
     private var bookGroupLiveData: LiveData<List<BookGroup>>? = null
     private val bookGroups = mutableListOf<BookGroup>()
@@ -107,10 +110,12 @@ class BookshelfFragment : VMBaseFragment<BookshelfViewModel>(R.layout.fragment_b
         tabLayout.isTabIndicatorFullWidth = false
         tabLayout.tabMode = TabLayout.MODE_SCROLLABLE
         tabLayout.setSelectedTabIndicatorColor(requireContext().accentColor)
-        tabLayout.setupWithViewPager(binding.viewPagerBookshelf)
         binding.viewPagerBookshelf.offscreenPageLimit = 1
-        adapter = TabFragmentPageAdapter(childFragmentManager)
+        adapter = TabFragmentPageAdapter()
         binding.viewPagerBookshelf.adapter = adapter
+        TabLayoutMediator(tabLayout, binding.viewPagerBookshelf) { tab, i ->
+            tab.text = bookGroups[i].groupName
+        }.attach()
     }
 
     private fun initBookGroupData() {
@@ -240,29 +245,21 @@ class BookshelfFragment : VMBaseFragment<BookshelfViewModel>(R.layout.fragment_b
         }.show()
     }
 
-    private inner class TabFragmentPageAdapter(fm: FragmentManager) :
-        FragmentStatePagerAdapter(fm, BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT) {
+    private inner class TabFragmentPageAdapter :
+        FragmentStateAdapter(this) {
 
-        override fun getPageTitle(position: Int): CharSequence {
-            return bookGroups[position].groupName
-        }
-
-        override fun getItemPosition(`object`: Any): Int {
-            return POSITION_NONE
-        }
-
-        override fun getItem(position: Int): Fragment {
+        override fun getItemId(position: Int): Long {
             val group = bookGroups[position]
-            return BooksFragment.newInstance(position, group.groupId)
+            return group.groupId
         }
 
-        override fun getCount(): Int {
+        override fun getItemCount(): Int {
             return bookGroups.size
         }
 
-        override fun instantiateItem(container: ViewGroup, position: Int): Any {
-            val fragment = super.instantiateItem(container, position) as BooksFragment
+        override fun createFragment(position: Int): Fragment {
             val group = bookGroups[position]
+            val fragment = BooksFragment.newInstance(position, group.groupId)
             fragmentMap[group.groupId] = fragment
             return fragment
         }
diff --git a/app/src/main/res/layout/fragment_bookshelf.xml b/app/src/main/res/layout/fragment_bookshelf.xml
index 4fbff35c3..0986b9bea 100644
--- a/app/src/main/res/layout/fragment_bookshelf.xml
+++ b/app/src/main/res/layout/fragment_bookshelf.xml
@@ -13,7 +13,7 @@
         app:title="@string/bookshelf"
         app:contentLayout="@layout/view_tab_layout_min" />
 
-    <androidx.viewpager.widget.ViewPager
+    <androidx.viewpager2.widget.ViewPager2
         android:id="@+id/view_pager_bookshelf"
         android:layout_width="match_parent"
         android:layout_height="match_parent" />