Android: Migrate to ViewPager2

Source/Android/app/build.gradle.kts

@@ -131,6 +131,7 @@ dependencies {
     implementation("androidx.core:core-splashscreen:1.0.1")
     implementation("androidx.preference:preference-ktx:1.2.1")
     implementation("androidx.profileinstaller:profileinstaller:1.3.1")
+    implementation("androidx.viewpager2:viewpager2:1.1.0")
 
     // Kotlin extensions for lifecycle components
     implementation("androidx.lifecycle:lifecycle-viewmodel-ktx:2.7.0")

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/adapters/PlatformStateAdapter.kt

@@ -3,32 +3,34 @@
 package org.dolphinemu.dolphinemu.adapters
 
 import androidx.fragment.app.Fragment
-import androidx.fragment.app.FragmentManager
-import androidx.fragment.app.FragmentPagerAdapter
+import androidx.fragment.app.FragmentActivity
 import androidx.swiperefreshlayout.widget.SwipeRefreshLayout.OnRefreshListener
+import androidx.viewpager2.adapter.FragmentStateAdapter
 import org.dolphinemu.dolphinemu.R
 import org.dolphinemu.dolphinemu.ui.platform.Platform
 import org.dolphinemu.dolphinemu.ui.platform.PlatformGamesFragment
 
-class PlatformPagerAdapter(
-    fm: FragmentManager,
+class PlatformStateAdapter(
+    fa: FragmentActivity,
     private val onRefreshListener: OnRefreshListener
-) : FragmentPagerAdapter(fm, BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT) {
-    override fun getItem(position: Int): Fragment {
+) : FragmentStateAdapter(fa) {
+
+    private val tabIcons = intArrayOf(
+        R.drawable.ic_gamecube,
+        R.drawable.ic_wii,
+        R.drawable.ic_folder
+    )
+
+    override fun createFragment(position: Int): Fragment {
         val platform = Platform.fromPosition(position)
         val fragment = PlatformGamesFragment.newInstance(platform)
         fragment.setOnRefreshListener(onRefreshListener)
         return fragment
     }
 
-    override fun getCount(): Int = TAB_ICONS.size
+    override fun getItemCount(): Int = tabIcons.size
 
-    companion object {
-        @JvmField
-        val TAB_ICONS = intArrayOf(
-            R.drawable.ic_gamecube,
-            R.drawable.ic_wii,
-            R.drawable.ic_folder
-        )
+    fun getTabIcon(position: Int): Int {
+        return tabIcons[position]
     }
 }

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/ui/main/MainActivity.kt

@@ -18,9 +18,10 @@ import androidx.swiperefreshlayout.widget.SwipeRefreshLayout.OnRefreshListener
 import com.google.android.material.appbar.AppBarLayout
 import com.google.android.material.color.MaterialColors
 import com.google.android.material.tabs.TabLayout
+import com.google.android.material.tabs.TabLayoutMediator
 import org.dolphinemu.dolphinemu.R
 import org.dolphinemu.dolphinemu.activities.EmulationActivity
-import org.dolphinemu.dolphinemu.adapters.PlatformPagerAdapter
+import org.dolphinemu.dolphinemu.adapters.PlatformStateAdapter
 import org.dolphinemu.dolphinemu.databinding.ActivityMainBinding
 import org.dolphinemu.dolphinemu.features.settings.model.IntSetting
 import org.dolphinemu.dolphinemu.features.settings.model.NativeConfig
@@ -282,26 +283,21 @@ class MainActivity : AppCompatActivity(), MainView, OnRefreshListener, ThemeProv
 
     // Don't call this before DirectoryInitialization completes.
     private fun setPlatformTabsAndStartGameFileCacheService() {
-        val platformPagerAdapter = PlatformPagerAdapter(
-            supportFragmentManager, this
-        )
-        binding.pagerPlatforms.adapter = platformPagerAdapter
-        binding.pagerPlatforms.offscreenPageLimit = platformPagerAdapter.count
-        binding.tabsPlatforms.setupWithViewPager(binding.pagerPlatforms)
-        binding.tabsPlatforms.addOnTabSelectedListener(
-            object : TabLayout.ViewPagerOnTabSelectedListener(binding.pagerPlatforms) {
-                override fun onTabSelected(tab: TabLayout.Tab) {
-                    super.onTabSelected(tab)
-                    IntSetting.MAIN_LAST_PLATFORM_TAB.setInt(
-                        NativeConfig.LAYER_BASE,
-                        tab.position
-                    )
-                }
-            })
+        val platformStateAdapter = PlatformStateAdapter(this, this)
+        binding.pagerPlatforms.adapter = platformStateAdapter
+        binding.pagerPlatforms.offscreenPageLimit = platformStateAdapter.itemCount
+        TabLayoutMediator(binding.tabsPlatforms, binding.pagerPlatforms) { tab, position ->
+            tab.setIcon(platformStateAdapter.getTabIcon(position))
+        }.attach()
+        binding.tabsPlatforms.addOnTabSelectedListener(object : TabLayout.OnTabSelectedListener {
+            override fun onTabSelected(tab: TabLayout.Tab) {
+                IntSetting.MAIN_LAST_PLATFORM_TAB.setInt(NativeConfig.LAYER_BASE, tab.position)
+            }
 
-        for (i in PlatformPagerAdapter.TAB_ICONS.indices) {
-            binding.tabsPlatforms.getTabAt(i)?.setIcon(PlatformPagerAdapter.TAB_ICONS[i])
-        }
+            override fun onTabUnselected(tab: TabLayout.Tab) {}
+
+            override fun onTabReselected(tab: TabLayout.Tab) {}
+        })
 
         binding.pagerPlatforms.currentItem = IntSetting.MAIN_LAST_PLATFORM_TAB.int
 

Source/Android/app/src/main/res/layout/activity_main.xml

@@ -35,7 +35,7 @@
 
     </com.google.android.material.appbar.AppBarLayout>
 
-    <androidx.viewpager.widget.ViewPager
+    <androidx.viewpager2.widget.ViewPager2
         android:id="@+id/pager_platforms"
         android:layout_width="match_parent"
         android:layout_height="match_parent"