feat(Android): Add focused states on page transitions

android/src/main/java/com/swmansion/rnscreens/ScreenFragment.kt

@@ -2,13 +2,16 @@ package com.swmansion.rnscreens
 
 import android.annotation.SuppressLint
 import android.app.Activity
+import android.app.UiModeManager
 import android.content.Context
+import android.content.res.Configuration
 import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import android.view.ViewParent
 import android.widget.FrameLayout
+import androidx.core.content.getSystemService
 import androidx.fragment.app.Fragment
 import com.facebook.react.bridge.ReactContext
 import com.facebook.react.bridge.UiThreadUtil
@@ -155,6 +158,10 @@ open class ScreenFragment : Fragment, ScreenFragmentWrapper {
     override val childScreenContainers: List<ScreenContainer>
         get() = mChildScreenContainers
 
+    fun isTelevision(): Boolean {
+        return context?.getSystemService<UiModeManager>()?.currentModeType == Configuration.UI_MODE_TYPE_TELEVISION
+    }
+
     override fun canDispatchLifecycleEvent(event: ScreenLifecycleEvent): Boolean = when (event) {
         ScreenLifecycleEvent.WillAppear -> canDispatchWillAppear
         ScreenLifecycleEvent.Appear -> canDispatchAppear

android/src/main/java/com/swmansion/rnscreens/ScreenStackFragment.kt

@@ -26,6 +26,8 @@ class ScreenStackFragment : ScreenFragment, ScreenStackFragmentWrapper {
     private var mShadowHidden = false
     private var mIsTranslucent = false
 
+    private var mLastFocusedChild: View? = null
+
     var searchView: CustomSearchView? = null
     var onSearchViewCreate: ((searchView: CustomSearchView) -> Unit)? = null
 
@@ -89,6 +91,11 @@ class ScreenStackFragment : ScreenFragment, ScreenStackFragmentWrapper {
         }
     }
 
+    override fun onStart() {
+        mLastFocusedChild?.requestFocus()
+        super.onStart()
+    }
+
     override fun onCreateView(
         inflater: LayoutInflater,
         container: ViewGroup?,
@@ -123,6 +130,11 @@ class ScreenStackFragment : ScreenFragment, ScreenStackFragmentWrapper {
         return view
     }
 
+    override fun onStop() {
+        mLastFocusedChild = findLastFocusedChild()
+        super.onStop()
+    }
+
     override fun onPrepareOptionsMenu(menu: Menu) {
         updateToolbarMenu(menu)
         return super.onPrepareOptionsMenu(menu)
@@ -163,6 +175,19 @@ class ScreenStackFragment : ScreenFragment, ScreenStackFragmentWrapper {
         }
     }
 
+    private fun findLastFocusedChild(): View? {
+        // If current device is not television, we don't want to save last focused child.
+        if (!isTelevision()) return null
+
+        var view: View? = screen
+        while (view != null) {
+            if (view.isFocused) return view
+            view = if (view is ViewGroup) view.focusedChild else null
+        }
+
+        return null
+    }
+
     override fun canNavigateBack(): Boolean {
         val container: ScreenContainer? = screen.container
         check(container is ScreenStack) { "ScreenStackFragment added into a non-stack container" }