Add built-in support for saving and restoring scroll and view states

dpadrecyclerview/api/dpadrecyclerview.api

@@ -562,3 +562,26 @@ public abstract interface class com/rubensousa/dpadrecyclerview/spacing/DpadSpac
 	public abstract fun shouldApplySpacing (Landroidx/recyclerview/widget/RecyclerView$ViewHolder;I)Z
 }
 
+public final class com/rubensousa/dpadrecyclerview/state/DpadScrollState {
+	public final fun clear ()V
+	public final fun clear (Ljava/lang/String;)V
+	public final fun restore (Lcom/rubensousa/dpadrecyclerview/DpadRecyclerView;Ljava/lang/String;Landroidx/recyclerview/widget/RecyclerView$Adapter;)V
+	public final fun save (Lcom/rubensousa/dpadrecyclerview/DpadRecyclerView;Ljava/lang/String;Z)V
+	public static synthetic fun save$default (Lcom/rubensousa/dpadrecyclerview/state/DpadScrollState;Lcom/rubensousa/dpadrecyclerview/DpadRecyclerView;Ljava/lang/String;ZILjava/lang/Object;)V
+}
+
+public final class com/rubensousa/dpadrecyclerview/state/DpadStateRegistry {
+	public fun <init> (Landroidx/savedstate/SavedStateRegistryOwner;)V
+	public final fun getScrollState ()Lcom/rubensousa/dpadrecyclerview/state/DpadScrollState;
+	public final fun getViewHolderState ()Lcom/rubensousa/dpadrecyclerview/state/DpadViewHolderState;
+	public final fun setSaveInstanceStateEnabled (Z)V
+}
+
+public final class com/rubensousa/dpadrecyclerview/state/DpadViewHolderState {
+	public final fun clear ()V
+	public final fun clear (Ljava/lang/String;)V
+	public final fun restoreState (Landroidx/recyclerview/widget/RecyclerView$ViewHolder;Ljava/lang/String;Z)V
+	public static synthetic fun restoreState$default (Lcom/rubensousa/dpadrecyclerview/state/DpadViewHolderState;Landroidx/recyclerview/widget/RecyclerView$ViewHolder;Ljava/lang/String;ZILjava/lang/Object;)V
+	public final fun saveState (Landroidx/recyclerview/widget/RecyclerView$ViewHolder;Ljava/lang/String;)V
+}
+

dpadrecyclerview/build.gradle

@@ -57,6 +57,7 @@ android {
 dependencies {
     api libs.androidx.recyclerview
     implementation libs.androidx.collection
+    implementation libs.androidx.fragment
 
     // Required for dependency resolution
     debugImplementation libs.guava

dpadrecyclerview/src/androidTest/kotlin/com/rubensousa/dpadrecyclerview/test/TestNestedListFragment.kt

@@ -25,6 +25,8 @@ import androidx.fragment.app.Fragment
 import androidx.recyclerview.widget.RecyclerView
 import com.rubensousa.dpadrecyclerview.DpadRecyclerView
 import com.rubensousa.dpadrecyclerview.OnViewFocusedListener
+import com.rubensousa.dpadrecyclerview.state.DpadScrollState
+import com.rubensousa.dpadrecyclerview.state.DpadStateRegistry
 import com.rubensousa.dpadrecyclerview.test.tests.AbstractTestAdapter
 import com.rubensousa.dpadrecyclerview.testfixtures.DpadFocusEvent
 
@@ -34,6 +36,7 @@ class TestNestedListFragment : Fragment(R.layout.dpadrecyclerview_test_container
         itemLayoutId = R.layout.dpadrecyclerview_item_horizontal,
         numberOfItems = 200
     )
+    private val stateRegistry = DpadStateRegistry(this)
     private val parentFocusEvents = arrayListOf<DpadFocusEvent>()
     private val childFocusEvents = arrayListOf<DpadFocusEvent>()
     private val parentFocusListener = object : OnViewFocusedListener {
@@ -52,7 +55,11 @@ class TestNestedListFragment : Fragment(R.layout.dpadrecyclerview_test_container
             childFocusEvents.add(DpadFocusEvent(parent, child, parent.layoutPosition))
         }
     }
-    private val nestedAdapter = NestedAdapter(configuration, childFocusListener)
+    private val nestedAdapter = NestedAdapter(
+        configuration = configuration,
+        onViewFocusedListener = childFocusListener,
+        scrollState = stateRegistry.getScrollState()
+    )
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
@@ -70,48 +77,63 @@ class TestNestedListFragment : Fragment(R.layout.dpadrecyclerview_test_container
 
     class NestedAdapter(
         private val configuration: TestAdapterConfiguration,
-        private val onViewFocusedListener: OnViewFocusedListener
+        private val onViewFocusedListener: OnViewFocusedListener,
+        private val scrollState: DpadScrollState,
     ) : AbstractTestAdapter<ListViewHolder>(configuration) {
 
         override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ListViewHolder {
             return ListViewHolder(
                 LayoutInflater.from(parent.context)
                     .inflate(R.layout.dpadrecyclerview_nested_list, parent, false),
                 configuration,
-                onViewFocusedListener
+                onViewFocusedListener,
             )
         }
 
         override fun onBindViewHolder(holder: ListViewHolder, position: Int) {
             holder.bind(position)
+            scrollState.restore(
+                recyclerView = holder.recyclerView,
+                key = position.toString(),
+                adapter = holder.adapter
+            )
         }
 
-    }
+        override fun onViewRecycled(holder: ListViewHolder) {
+            super.onViewRecycled(holder)
+            scrollState.save(
+                recyclerView = holder.recyclerView,
+                key = holder.absoluteAdapterPosition.toString(),
+                detachAdapter = true
+            )
+        }
 
+    }
 
     class ListViewHolder(
         val view: View,
         val configuration: TestAdapterConfiguration,
         onViewFocusedListener: OnViewFocusedListener,
     ) : RecyclerView.ViewHolder(view) {
 
-        private val adapter = TestAdapter(
+         val adapter = TestAdapter(
             adapterConfiguration = configuration,
             onViewHolderSelected = { position -> },
             onViewHolderDeselected = { position -> }
         )
         private val textView = view.findViewById<TextView>(R.id.textView)
-        private val recyclerView = view.findViewById<DpadRecyclerView>(R.id.nestedRecyclerView)
+
+        val recyclerView = view.findViewById<DpadRecyclerView>(R.id.nestedRecyclerView)
 
         init {
-            recyclerView.adapter = adapter
             recyclerView.addOnViewFocusedListener(onViewFocusedListener)
         }
 
         fun bind(position: Int) {
+            recyclerView.tag = position
             textView.text = "List $position"
+            textView.freezesText = true
         }
-
     }
 
 }

dpadrecyclerview/src/androidTest/kotlin/com/rubensousa/dpadrecyclerview/test/tests/selection/SaveRestoreStateTest.kt

@@ -16,52 +16,48 @@
 
 package com.rubensousa.dpadrecyclerview.test.tests.selection
 
-import androidx.recyclerview.widget.RecyclerView
+import androidx.fragment.app.testing.FragmentScenario
+import androidx.fragment.app.testing.launchFragmentInContainer
+import androidx.test.espresso.Espresso
 import androidx.test.espresso.assertion.ViewAssertions
 import androidx.test.espresso.matcher.ViewMatchers
+import androidx.test.espresso.matcher.ViewMatchers.withId
+import androidx.test.espresso.matcher.ViewMatchers.withTagValue
 import com.google.common.truth.Truth.assertThat
-import com.rubensousa.dpadrecyclerview.ChildAlignment
-import com.rubensousa.dpadrecyclerview.ParentAlignment
-import com.rubensousa.dpadrecyclerview.ParentAlignment.Edge
-import com.rubensousa.dpadrecyclerview.test.TestLayoutConfiguration
+import com.rubensousa.dpadrecyclerview.test.TestNestedListFragment
 import com.rubensousa.dpadrecyclerview.test.helpers.assertFocusPosition
 import com.rubensousa.dpadrecyclerview.test.helpers.assertOnRecyclerView
 import com.rubensousa.dpadrecyclerview.test.helpers.getItemViewBounds
 import com.rubensousa.dpadrecyclerview.test.helpers.getRecyclerViewBounds
-import com.rubensousa.dpadrecyclerview.test.tests.DpadRecyclerViewTest
+import com.rubensousa.dpadrecyclerview.test.helpers.waitForCondition
 import com.rubensousa.dpadrecyclerview.testing.KeyEvents
+import com.rubensousa.dpadrecyclerview.testing.R
+import com.rubensousa.dpadrecyclerview.testing.assertions.DpadRecyclerViewAssertions
 import com.rubensousa.dpadrecyclerview.testing.rules.DisableIdleTimeoutRule
+import org.hamcrest.Matchers
+import org.hamcrest.Matchers.allOf
 import org.junit.Before
 import org.junit.Rule
 import org.junit.Test
 
-class SaveRestoreStateTest : DpadRecyclerViewTest() {
+class SaveRestoreStateTest {
 
     @get:Rule
     val idleTimeoutRule = DisableIdleTimeoutRule()
 
-    override fun getDefaultLayoutConfiguration(): TestLayoutConfiguration {
-        return TestLayoutConfiguration(
-            spans = 1,
-            orientation = RecyclerView.VERTICAL,
-            parentAlignment = ParentAlignment(
-                edge = Edge.MIN_MAX
-            ),
-            childAlignment = ChildAlignment(offset = 0)
-        )
-    }
+    private lateinit var fragmentScenario: FragmentScenario<TestNestedListFragment>
 
     @Before
     fun setup() {
-        launchFragment()
+        fragmentScenario = launchFragment()
     }
 
     @Test
     fun testSelectionStateIsSavedAndRestored() {
         KeyEvents.pressDown(times = 5)
         assertFocusPosition(5)
 
-        recreateFragment()
+        fragmentScenario.recreate()
 
         val recyclerViewBounds = getRecyclerViewBounds()
         val viewBounds = getItemViewBounds(position = 5)
@@ -70,4 +66,52 @@ class SaveRestoreStateTest : DpadRecyclerViewTest() {
         assertFocusPosition(5)
     }
 
+    @Test
+    fun testSelectionStateAcrossNestedListsIsSaved() {
+        // given
+        KeyEvents.pressRight(times = 5)
+
+        // when
+        KeyEvents.pressDown(times = 25)
+        KeyEvents.pressUp(times = 25)
+
+        // then
+        Espresso.onView(
+            allOf(
+                withId(com.rubensousa.dpadrecyclerview.test.R.id.nestedRecyclerView),
+                withTagValue(Matchers.`is`(0))
+            )
+        ).check(DpadRecyclerViewAssertions.isSelected(position = 5))
+    }
+
+    @Test
+    fun testSelectionStateAcrossNestedListsSurvivesConfigurationChanges() {
+        // given
+        KeyEvents.pressRight(times = 5)
+        KeyEvents.pressDown(times = 25)
+        KeyEvents.pressUp(times = 25)
+
+        // when
+        fragmentScenario.recreate()
+
+        // then
+        Espresso.onView(
+            allOf(
+                withId(com.rubensousa.dpadrecyclerview.test.R.id.nestedRecyclerView),
+                withTagValue(Matchers.`is`(0))
+            )
+        ).check(DpadRecyclerViewAssertions.isSelected(position = 5))
+    }
+
+    private fun launchFragment(): FragmentScenario<TestNestedListFragment> {
+        return launchFragmentInContainer<TestNestedListFragment>(
+            themeResId = R.style.DpadRecyclerViewTestTheme
+        ).also {
+            fragmentScenario = it
+            waitForCondition("Waiting for layout pass") { recyclerView ->
+                !recyclerView.isLayoutRequested
+            }
+        }
+    }
+
 }