Fix configuration changes on folding phones

- Remove container id values from extensions of `FragmentTransitions`
- Update `FeatureFragments` to be explicit with container ids
- Update `BookmarkListScreen` to collect the previous state when a bookmark detail is being displayed
- Update how the `MainActivity` handles configuration changes from folding phones

app/src/main/kotlin/com/fibelatti/pinboard/core/extension/FragmentTransitions.kt

@@ -1,5 +1,6 @@
 package com.fibelatti.pinboard.core.extension
 
+import androidx.annotation.IdRes
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.FragmentActivity
 import androidx.fragment.app.commit
@@ -16,10 +17,10 @@ fun FragmentActivity.popTo(tag: String) {
 }
 
 fun FragmentActivity.slideFromTheRight(
+    @IdRes containerId: Int,
     fragment: Fragment,
     tag: String,
     addToBackStack: Boolean = true,
-    containerId: Int = R.id.fragment_host,
 ) {
     supportFragmentManager.commit {
         setCustomAnimations(
@@ -37,10 +38,10 @@ fun FragmentActivity.slideFromTheRight(
 }
 
 fun FragmentActivity.slideUp(
+    @IdRes containerId: Int,
     fragment: Fragment,
     tag: String,
     addToBackStack: Boolean = true,
-    containerId: Int = R.id.fragment_host,
 ) {
     supportFragmentManager.commit {
         setCustomAnimations(R.anim.slide_up, -1, -1, R.anim.slide_down)

app/src/main/kotlin/com/fibelatti/pinboard/features/FeatureFragments.kt

@@ -25,14 +25,6 @@ import javax.inject.Inject
 
 class FeatureFragments @Inject constructor(private val activity: FragmentActivity) {
 
-    var multiPanelEnabled: Boolean = false
-
-    private fun getDetailContainerId(): Int = if (multiPanelEnabled) {
-        R.id.fragment_host_side_panel
-    } else {
-        R.id.fragment_host
-    }
-
     fun showLogin() {
         with(activity.supportFragmentManager) {
             if (findFragmentByTag(AuthFragment.TAG) == null) {
@@ -63,9 +55,9 @@ class FeatureFragments @Inject constructor(private val activity: FragmentActivit
 
         if (activity.supportFragmentManager.findFragmentByTag(tag) == null) {
             activity.slideFromTheRight(
+                containerId = R.id.fragment_host_side_panel,
                 fragment = activity.createFragment<PostDetailFragment>(),
                 tag = tag,
-                containerId = getDetailContainerId(),
             )
         } else {
             activity.popTo(tag)
@@ -83,25 +75,41 @@ class FeatureFragments @Inject constructor(private val activity: FragmentActivit
 
     fun showSearch() {
         if (activity.supportFragmentManager.findFragmentByTag(PostSearchFragment.TAG) == null) {
-            activity.slideUp(activity.createFragment<PostSearchFragment>(), PostSearchFragment.TAG)
+            activity.slideUp(
+                containerId = R.id.fragment_host,
+                fragment = activity.createFragment<PostSearchFragment>(),
+                tag = PostSearchFragment.TAG,
+            )
         }
     }
 
     fun showAddPost() {
         if (activity.supportFragmentManager.findFragmentByTag(EditPostFragment.TAG) == null) {
-            activity.slideUp(activity.createFragment<EditPostFragment>(), EditPostFragment.TAG)
+            activity.slideUp(
+                containerId = R.id.fragment_host,
+                fragment = activity.createFragment<EditPostFragment>(),
+                tag = EditPostFragment.TAG,
+            )
         }
     }
 
     fun showTags() {
         if (activity.supportFragmentManager.findFragmentByTag(TagsFragment.TAG) == null) {
-            activity.slideUp(activity.createFragment<TagsFragment>(), TagsFragment.TAG)
+            activity.slideUp(
+                containerId = R.id.fragment_host,
+                fragment = activity.createFragment<TagsFragment>(),
+                tag = TagsFragment.TAG,
+            )
         }
     }
 
     fun showNotes() {
         if (activity.supportFragmentManager.findFragmentByTag(NoteListFragment.TAG) == null) {
-            activity.slideUp(activity.createFragment<NoteListFragment>(), NoteListFragment.TAG)
+            activity.slideUp(
+                containerId = R.id.fragment_host,
+                fragment = activity.createFragment<NoteListFragment>(),
+                tag = NoteListFragment.TAG,
+            )
         } else {
             activity.popTo(NoteListFragment.TAG)
         }
@@ -110,30 +118,39 @@ class FeatureFragments @Inject constructor(private val activity: FragmentActivit
     fun showNoteDetails() {
         if (activity.supportFragmentManager.findFragmentByTag(NoteDetailsFragment.TAG) == null) {
             activity.slideFromTheRight(
+                containerId = R.id.fragment_host_side_panel,
                 fragment = activity.createFragment<NoteDetailsFragment>(),
                 tag = NoteDetailsFragment.TAG,
-                containerId = getDetailContainerId(),
             )
         }
     }
 
     fun showPopular() {
         if (activity.supportFragmentManager.findFragmentByTag(PopularPostsFragment.TAG) == null) {
-            activity.slideUp(activity.createFragment<PopularPostsFragment>(), PopularPostsFragment.TAG)
+            activity.slideUp(
+                containerId = R.id.fragment_host,
+                fragment = activity.createFragment<PopularPostsFragment>(),
+                tag = PopularPostsFragment.TAG,
+            )
         } else {
             activity.popTo(PopularPostsFragment.TAG)
         }
     }
 
     fun showPreferences() {
         if (activity.supportFragmentManager.findFragmentByTag(UserPreferencesFragment.TAG) == null) {
-            activity.slideUp(activity.createFragment<UserPreferencesFragment>(), UserPreferencesFragment.TAG)
+            activity.slideUp(
+                containerId = R.id.fragment_host,
+                fragment = activity.createFragment<UserPreferencesFragment>(),
+                tag = UserPreferencesFragment.TAG,
+            )
         }
     }
 
     fun showEditPost() {
         if (activity.supportFragmentManager.findFragmentByTag(EditPostFragment.TAG) == null) {
             activity.slideUp(
+                containerId = R.id.fragment_host,
                 fragment = activity.createFragment<EditPostFragment>(),
                 tag = EditPostFragment.TAG,
                 addToBackStack = !activity.intent.fromBuilder,

app/src/main/kotlin/com/fibelatti/pinboard/features/MainActivity.kt

@@ -1,22 +1,22 @@
 package com.fibelatti.pinboard.features
 
-import android.animation.ValueAnimator
 import android.content.Context
 import android.content.Intent
 import android.os.Bundle
+import android.transition.ChangeBounds
+import android.transition.TransitionManager
+import android.view.View
+import android.view.animation.LinearInterpolator
 import androidx.activity.OnBackPressedCallback
 import androidx.activity.viewModels
-import androidx.constraintlayout.widget.ConstraintLayout
-import androidx.core.animation.doOnEnd
+import androidx.constraintlayout.widget.ConstraintSet
 import androidx.core.view.WindowCompat
-import androidx.core.view.isGone
-import androidx.core.view.isVisible
-import androidx.core.view.updateLayoutParams
 import androidx.lifecycle.Lifecycle
 import androidx.lifecycle.lifecycleScope
 import androidx.lifecycle.repeatOnLifecycle
 import com.fibelatti.core.android.BaseIntentBuilder
 import com.fibelatti.core.android.intentExtras
+import com.fibelatti.core.extension.animateChangingTransitions
 import com.fibelatti.core.extension.doOnInitializeAccessibilityNodeInfo
 import com.fibelatti.core.extension.setupForAccessibility
 import com.fibelatti.core.extension.viewBinding
@@ -80,6 +80,50 @@ class MainActivity : BaseActivity() {
 
     private val binding by viewBinding(ActivityMainBinding::inflate)
 
+    // region ConstraintSets
+    private val constraintSetSidePanelHidden by lazy {
+        ConstraintSet().apply {
+            clone(binding.layoutContent)
+
+            connect(R.id.fragment_host, ConstraintSet.START, ConstraintSet.PARENT_ID, ConstraintSet.START)
+            connect(R.id.fragment_host, ConstraintSet.END, ConstraintSet.PARENT_ID, ConstraintSet.END)
+            constrainPercentWidth(R.id.fragment_host, 1f)
+
+            connect(R.id.fragment_host_side_panel, ConstraintSet.START, R.id.fragment_host, ConstraintSet.END)
+            connect(R.id.fragment_host_side_panel, ConstraintSet.END, ConstraintSet.PARENT_ID, ConstraintSet.END)
+            setVisibility(R.id.fragment_host_side_panel, View.GONE)
+        }
+    }
+
+    private val constraintSetSidePanelOverlap by lazy {
+        ConstraintSet().apply {
+            clone(binding.layoutContent)
+
+            connect(R.id.fragment_host, ConstraintSet.START, ConstraintSet.PARENT_ID, ConstraintSet.START)
+            connect(R.id.fragment_host, ConstraintSet.END, ConstraintSet.PARENT_ID, ConstraintSet.END)
+            constrainPercentWidth(R.id.fragment_host, 1f)
+
+            connect(R.id.fragment_host_side_panel, ConstraintSet.START, ConstraintSet.PARENT_ID, ConstraintSet.START)
+            connect(R.id.fragment_host_side_panel, ConstraintSet.END, ConstraintSet.PARENT_ID, ConstraintSet.END)
+            setVisibility(R.id.fragment_host_side_panel, View.VISIBLE)
+        }
+    }
+
+    private val constraintSetSidePanelDivided by lazy {
+        ConstraintSet().apply {
+            clone(binding.layoutContent)
+
+            connect(R.id.fragment_host, ConstraintSet.START, ConstraintSet.PARENT_ID, ConstraintSet.START)
+            connect(R.id.fragment_host, ConstraintSet.END, R.id.fragment_host_side_panel, ConstraintSet.START)
+            constrainPercentWidth(R.id.fragment_host, 0.4f)
+
+            connect(R.id.fragment_host_side_panel, ConstraintSet.START, R.id.fragment_host, ConstraintSet.END)
+            connect(R.id.fragment_host_side_panel, ConstraintSet.END, ConstraintSet.PARENT_ID, ConstraintSet.END)
+            setVisibility(R.id.fragment_host_side_panel, View.VISIBLE)
+        }
+    }
+    // endregion ConstraintSets
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(binding.root)
@@ -107,13 +151,14 @@ class MainActivity : BaseActivity() {
 
         binding.root.addView(
             widthWindowSizeClassReactiveView { windowSizeClass ->
-                featureFragments.multiPanelEnabled = windowSizeClass != WindowSizeClass.COMPACT
                 mainViewModel.updateState { currentState ->
                     currentState.copy(multiPanelEnabled = windowSizeClass != WindowSizeClass.COMPACT)
                 }
             },
         )
 
+        binding.layoutContent.animateChangingTransitions()
+
         binding.composeViewTopBar.setThemedContent {
             MainTopAppBar(
                 mainViewModel = mainViewModel,
@@ -168,6 +213,8 @@ class MainActivity : BaseActivity() {
     private fun handleContent(content: Content) {
         onBackPressedCallback.isEnabled = (content as? ContentWithHistory)?.previousContent !is ExternalContent
 
+        setupSidePanel(show = content is SidePanelContent)
+
         if (isRecreating) {
             isRecreating = false
             return
@@ -177,7 +224,6 @@ class MainActivity : BaseActivity() {
             return
         }
 
-        setupSidePanel(show = content is SidePanelContent)
         showContentScreen(content)
     }
 
@@ -218,37 +264,18 @@ class MainActivity : BaseActivity() {
             currentState.copy(multiPanelContent = show)
         }
 
-        val showSidePanel = featureFragments.multiPanelEnabled && show
-
-        when {
-            showSidePanel && binding.fragmentHostSidePanel.isGone -> {
-                binding.fragmentHostSidePanel.isVisible = true
-                animatedSidePanelWidth(endWidth = binding.root.width / 2)
-            }
-
-            !showSidePanel && binding.fragmentHostSidePanel.isVisible -> {
-                animatedSidePanelWidth(endWidth = 0) {
-                    binding.fragmentHostSidePanel.isVisible = false
-                }
-            }
+        val constraintSet = when {
+            show && mainViewModel.state.value.multiPanelEnabled -> constraintSetSidePanelDivided
+            show -> constraintSetSidePanelOverlap
+            else -> constraintSetSidePanelHidden
         }
-    }
 
-    private inline fun animatedSidePanelWidth(
-        endWidth: Int,
-        crossinline doOnEnd: () -> Unit = {},
-    ) {
-        ValueAnimator.ofInt(binding.fragmentHostSidePanel.measuredWidth, endWidth)
-            .apply {
-                addUpdateListener { valueAnimator ->
-                    val value = valueAnimator.animatedValue as Int
-                    binding.fragmentHostSidePanel.updateLayoutParams<ConstraintLayout.LayoutParams> {
-                        width = value
-                    }
-                }
-                doOnEnd { doOnEnd() }
-            }
-            .start()
+        val transition = ChangeBounds()
+            .setInterpolator(LinearInterpolator())
+            .setDuration(300)
+
+        TransitionManager.beginDelayedTransition(binding.layoutContent, transition)
+        constraintSet.applyTo(binding.layoutContent)
     }
 
     override fun handleError(error: Throwable?, postAction: () -> Unit) {

app/src/main/kotlin/com/fibelatti/pinboard/features/posts/presentation/BookmarkListScreen.kt

@@ -88,37 +88,41 @@ fun BookmarkListScreen(
     Surface(
         color = ExtendedTheme.colors.backgroundNoOverlay,
     ) {
-        val appState by appStateViewModel.postListContent.collectAsStateWithLifecycle(initialValue = null)
-        val postListContent by rememberUpdatedState(newValue = appState ?: return@Surface)
+        val postListContent by appStateViewModel.postListContent.collectAsStateWithLifecycle(initialValue = null)
+        val postDetailContent by appStateViewModel.postDetailContent.collectAsStateWithLifecycle(initialValue = null)
 
-        val postListLoading = postListContent.shouldLoad != Loaded
+        val currentState by rememberUpdatedState(
+            newValue = postListContent ?: postDetailContent?.previousContent ?: return@Surface,
+        )
+
+        val postListLoading = currentState.shouldLoad != Loaded
         val postDetailScreenState by postDetailViewModel.screenState.collectAsStateWithLifecycle()
 
         val postListError by postListViewModel.error.collectAsStateWithLifecycle()
         val postDetailError by postDetailViewModel.error.collectAsStateWithLifecycle()
         val hasError = postListError != null || postDetailError != null
 
-        val shouldLoadContent = postListContent.shouldLoad is ShouldLoadFirstPage ||
-            postListContent.shouldLoad is ShouldForceLoad ||
-            postListContent.shouldLoad is ShouldLoadNextPage
+        val shouldLoadContent = currentState.shouldLoad is ShouldLoadFirstPage ||
+            currentState.shouldLoad is ShouldForceLoad ||
+            currentState.shouldLoad is ShouldLoadNextPage
 
-        LaunchedEffect(shouldLoadContent, postListContent) {
-            if (shouldLoadContent) postListViewModel.loadContent(postListContent)
+        LaunchedEffect(shouldLoadContent, currentState) {
+            if (shouldLoadContent) postListViewModel.loadContent(currentState)
         }
 
         BookmarkListScreen(
-            posts = postListContent.posts,
+            posts = currentState.posts,
             isLoading = (postListLoading || postDetailScreenState.isLoading) && !hasError,
             onScrollDirectionChanged = mainViewModel::setCurrentScrollDirection,
             onNextPageRequested = { appStateViewModel.runAction(GetNextPostPage) },
-            searchParameters = postListContent.searchParameters,
+            searchParameters = currentState.searchParameters,
             onClearClicked = { appStateViewModel.runAction(ClearSearch) },
             onShareClicked = onShareClicked,
             onPullToRefresh = { appStateViewModel.runAction(Refresh()) },
             onPostClicked = { post -> appStateViewModel.runAction(ViewPost(post)) },
             onPostLongClicked = onPostLongClicked,
             onTagClicked = { post -> appStateViewModel.runAction(PostsForTag(post)) },
-            showPostDescription = postListContent.showDescription,
+            showPostDescription = currentState.showDescription,
         )
     }
 }