ui: add util for fragment objects

Add a utility to easily work with lifecycle-dependent fragment objects.

This reduces the code duplication required to maintain objects that
would leak after the destruction of a fragment. We normally would not
do this as a delegate, as that usually entails some lifecycle wizardry
that can easily break and crash the app in esoteric situations.
However, this this just extends the normal lifecycle without watching
any state, it seems to be pretty safe to use.

app/src/main/java/org/oxycblt/auxio/MainActivity.kt

@@ -30,7 +30,6 @@ import org.oxycblt.auxio.music.IndexerService
 import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.playback.system.PlaybackService
 import org.oxycblt.auxio.settings.Settings
-import org.oxycblt.auxio.settings.settings
 import org.oxycblt.auxio.util.androidViewModels
 import org.oxycblt.auxio.util.getSystemBarInsetsCompat
 import org.oxycblt.auxio.util.isNight

app/src/main/java/org/oxycblt/auxio/home/HomeFragment.kt

@@ -77,18 +77,20 @@ class HomeFragment : ViewBindingFragment<FragmentHomeBinding>(), Toolbar.OnMenuI
     private val homeModel: HomeViewModel by androidActivityViewModels()
     private val indexerModel: IndexerViewModel by activityViewModels()
 
-    private var storagePermissionLauncher: ActivityResultLauncher<String>? = null
+    // lifecycleObject builds this in the creation step, so doing this is okay.
-    private var sortItem: MenuItem? = null
+    private val storagePermissionLauncher: ActivityResultLauncher<String> by lifecycleObject {
+        registerForActivityResult(ActivityResultContracts.RequestPermission()) {
+            indexerModel.reindex()
+        }
+    }
+
+    private val sortItem: MenuItem by lifecycleObject { binding ->
+        binding.homeToolbar.menu.findItem(R.id.submenu_sorting)
+    }
 
     override fun onCreateBinding(inflater: LayoutInflater) = FragmentHomeBinding.inflate(inflater)
 
     override fun onBindingCreated(binding: FragmentHomeBinding, savedInstanceState: Bundle?) {
-        // Build the permission launcher here as you can only do it in onCreateView/onCreate
-        storagePermissionLauncher =
-            registerForActivityResult(ActivityResultContracts.RequestPermission()) {
-                indexerModel.reindex()
-            }
-
         binding.homeAppbar.apply {
             addOnOffsetChangedListener { _, offset ->
                 val range = binding.homeAppbar.totalScrollRange
@@ -100,10 +102,7 @@ class HomeFragment : ViewBindingFragment<FragmentHomeBinding>(), Toolbar.OnMenuI
             }
         }
 
-        binding.homeToolbar.apply {
+        binding.homeToolbar.setOnMenuItemClickListener(this@HomeFragment)
-            sortItem = menu.findItem(R.id.submenu_sorting)
-            setOnMenuItemClickListener(this@HomeFragment)
-        }
 
         updateTabConfiguration()
 
@@ -151,8 +150,6 @@ class HomeFragment : ViewBindingFragment<FragmentHomeBinding>(), Toolbar.OnMenuI
     override fun onDestroyBinding(binding: FragmentHomeBinding) {
         super.onDestroyBinding(binding)
         binding.homeToolbar.setOnMenuItemClickListener(null)
-        storagePermissionLauncher = null
-        sortItem = null
     }
 
     override fun onMenuItemClick(item: MenuItem): Boolean {
@@ -246,9 +243,7 @@ class HomeFragment : ViewBindingFragment<FragmentHomeBinding>(), Toolbar.OnMenuI
     }
 
     private fun updateSortMenu(displayMode: DisplayMode, isVisible: (Int) -> Boolean) {
-        val sortMenu =
+        val sortMenu = requireNotNull(sortItem.subMenu)
-            requireNotNull(sortItem?.subMenu) { "Cannot update sort menu while detached" }
-
         val toHighlight = homeModel.getSortForDisplay(displayMode)
 
         for (option in sortMenu) {
@@ -323,18 +318,14 @@ class HomeFragment : ViewBindingFragment<FragmentHomeBinding>(), Toolbar.OnMenuI
                     }
                 }
                 is Indexer.Response.NoPerms -> {
-                    val launcher =
-                        requireNotNull(storagePermissionLauncher) {
-                            "Cannot access permission launcher while detached"
-                        }
-
                     binding.homeIndexingProgress.visibility = View.INVISIBLE
                     binding.homeIndexingStatus.textSafe = getString(R.string.err_no_perms)
                     binding.homeIndexingAction.apply {
                         visibility = View.VISIBLE
                         text = getString(R.string.lbl_grant)
                         setOnClickListener {
-                            launcher.launch(Manifest.permission.READ_EXTERNAL_STORAGE)
+                            storagePermissionLauncher.launch(
+                                Manifest.permission.READ_EXTERNAL_STORAGE)
                         }
                     }
                 }

app/src/main/java/org/oxycblt/auxio/home/list/SongListFragment.kt

@@ -23,7 +23,6 @@ import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.FragmentHomeListBinding
 import org.oxycblt.auxio.music.Song
 import org.oxycblt.auxio.settings.Settings
-import org.oxycblt.auxio.settings.settings
 import org.oxycblt.auxio.ui.DisplayMode
 import org.oxycblt.auxio.ui.Item
 import org.oxycblt.auxio.ui.MenuItemListener
@@ -31,6 +30,7 @@ import org.oxycblt.auxio.ui.MonoAdapter
 import org.oxycblt.auxio.ui.SongViewHolder
 import org.oxycblt.auxio.ui.Sort
 import org.oxycblt.auxio.ui.SyncBackingData
+import org.oxycblt.auxio.util.context
 import org.oxycblt.auxio.util.formatDuration
 import org.oxycblt.auxio.util.launch
 import org.oxycblt.auxio.util.logEOrThrow
@@ -41,7 +41,7 @@ import org.oxycblt.auxio.util.logEOrThrow
  */
 class SongListFragment : HomeListFragment<Song>() {
     private val homeAdapter = SongsAdapter(this)
-    private val settings: Settings by settings()
+    private val settings: Settings by lifecycleObject { binding -> Settings(binding.context) }
 
     override fun onBindingCreated(binding: FragmentHomeListBinding, savedInstanceState: Bundle?) {
         super.onBindingCreated(binding, savedInstanceState)

app/src/main/java/org/oxycblt/auxio/home/tabs/TabCustomizeDialog.kt

@@ -26,11 +26,10 @@ import org.oxycblt.auxio.BuildConfig
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.DialogTabsBinding
 import org.oxycblt.auxio.settings.Settings
-import org.oxycblt.auxio.settings.settings
 import org.oxycblt.auxio.ui.DisplayMode
 import org.oxycblt.auxio.ui.ViewBindingDialogFragment
+import org.oxycblt.auxio.util.context
 import org.oxycblt.auxio.util.logD
-import org.oxycblt.auxio.util.requireAttached
 
 /**
  * The dialog for customizing library tabs.
@@ -38,9 +37,10 @@ import org.oxycblt.auxio.util.requireAttached
  */
 class TabCustomizeDialog : ViewBindingDialogFragment<DialogTabsBinding>(), TabAdapter.Listener {
     private val tabAdapter = TabAdapter(this)
-    private val settings: Settings by settings()
+    private val settings: Settings by lifecycleObject { binding -> Settings(binding.context) }
-    private var touchHelper: ItemTouchHelper? = null
+    private val touchHelper: ItemTouchHelper by lifecycleObject {
-    private var callback: TabDragCallback? = null
+        ItemTouchHelper(TabDragCallback(tabAdapter))
+    }
 
     override fun onCreateBinding(inflater: LayoutInflater) = DialogTabsBinding.inflate(inflater)
 
@@ -65,7 +65,7 @@ class TabCustomizeDialog : ViewBindingDialogFragment<DialogTabsBinding>(), TabAd
 
         binding.tabRecycler.apply {
             adapter = tabAdapter
-            requireTouchHelper().attachToRecyclerView(this)
+            touchHelper.attachToRecyclerView(this)
         }
     }
 
@@ -99,7 +99,7 @@ class TabCustomizeDialog : ViewBindingDialogFragment<DialogTabsBinding>(), TabAd
     }
 
     override fun onPickUpTab(viewHolder: RecyclerView.ViewHolder) {
-        requireTouchHelper().startDrag(viewHolder)
+        touchHelper.startDrag(viewHolder)
     }
 
     private fun findSavedTabState(savedInstanceState: Bundle?): Array<Tab>? {
@@ -111,19 +111,6 @@ class TabCustomizeDialog : ViewBindingDialogFragment<DialogTabsBinding>(), TabAd
         return null
     }
 
-    private fun requireTouchHelper(): ItemTouchHelper {
-        requireAttached()
-        val instance = touchHelper
-        if (instance != null) {
-            return instance
-        }
-        val newCallback = TabDragCallback(tabAdapter)
-        val newInstance = ItemTouchHelper(newCallback)
-        callback = newCallback
-        touchHelper = newInstance
-        return newInstance
-    }
-
     companion object {
         const val TAG = BuildConfig.APPLICATION_ID + ".tag.TAB_CUSTOMIZE"
         const val KEY_TABS = BuildConfig.APPLICATION_ID + ".key.PENDING_TABS"

app/src/main/java/org/oxycblt/auxio/music/dirs/MusicDirsDialog.kt

@@ -31,9 +31,9 @@ import org.oxycblt.auxio.databinding.DialogMusicDirsBinding
 import org.oxycblt.auxio.music.Directory
 import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.settings.Settings
-import org.oxycblt.auxio.settings.settings
 import org.oxycblt.auxio.ui.ViewBindingDialogFragment
 import org.oxycblt.auxio.util.androidActivityViewModels
+import org.oxycblt.auxio.util.context
 import org.oxycblt.auxio.util.getSystemServiceSafe
 import org.oxycblt.auxio.util.hardRestart
 import org.oxycblt.auxio.util.logD
@@ -48,7 +48,7 @@ class MusicDirsDialog :
     private val playbackModel: PlaybackViewModel by androidActivityViewModels()
 
     private val dirAdapter = MusicDirAdapter(this)
-    private val settings: Settings by settings()
+    private val settings: Settings by lifecycleObject { binding -> Settings(binding.context) }
     private var storageManager: StorageManager? = null
 
     override fun onCreateBinding(inflater: LayoutInflater) =

app/src/main/java/org/oxycblt/auxio/playback/PlaybackPanelFragment.kt

@@ -57,7 +57,9 @@ class PlaybackPanelFragment :
     private val playbackModel: PlaybackViewModel by androidActivityViewModels()
     private val navModel: NavigationViewModel by activityViewModels()
 
-    private var queueItem: MenuItem? = null
+    private val queueItem: MenuItem by lifecycleObject { binding ->
+        binding.playbackToolbar.menu.findItem(R.id.action_queue)
+    }
 
     override fun onCreateBinding(inflater: LayoutInflater) =
         FragmentPlaybackPanelBinding.inflate(inflater)
@@ -82,7 +84,6 @@ class PlaybackPanelFragment :
         binding.playbackToolbar.apply {
             setNavigationOnClickListener { navModel.mainNavigateTo(MainNavigationAction.Collapse) }
             setOnMenuItemClickListener(this@PlaybackPanelFragment)
-            queueItem = menu.findItem(R.id.action_queue)
         }
 
         binding.playbackSong.apply {
@@ -130,7 +131,6 @@ class PlaybackPanelFragment :
         binding.playbackToolbar.setOnMenuItemClickListener(null)
         binding.playbackSong.isSelected = false
         binding.playbackSeekBar.callback = null
-        queueItem = null
     }
 
     override fun onMenuItemClick(item: MenuItem): Boolean {
@@ -198,7 +198,6 @@ class PlaybackPanelFragment :
     }
 
     private fun updateNextUp(nextUp: List<Song>) {
-        requireNotNull(queueItem) { "Cannot update next up in non-view state" }.isEnabled =
+        queueItem.isEnabled = nextUp.isNotEmpty()
-            nextUp.isNotEmpty()
     }
 }

app/src/main/java/org/oxycblt/auxio/playback/PlaybackViewModel.kt

@@ -36,7 +36,6 @@ import org.oxycblt.auxio.playback.state.PlaybackStateDatabase
 import org.oxycblt.auxio.playback.state.PlaybackStateManager
 import org.oxycblt.auxio.playback.state.RepeatMode
 import org.oxycblt.auxio.settings.Settings
-import org.oxycblt.auxio.settings.settings
 import org.oxycblt.auxio.util.application
 import org.oxycblt.auxio.util.logE
 

app/src/main/java/org/oxycblt/auxio/playback/queue/QueueFragment.kt

@@ -29,7 +29,6 @@ import org.oxycblt.auxio.playback.PlaybackViewModel
 import org.oxycblt.auxio.ui.ViewBindingFragment
 import org.oxycblt.auxio.util.androidActivityViewModels
 import org.oxycblt.auxio.util.launch
-import org.oxycblt.auxio.util.requireAttached
 
 /**
  * A [Fragment] that shows the queue and enables editing as well.
@@ -37,9 +36,10 @@ import org.oxycblt.auxio.util.requireAttached
  */
 class QueueFragment : ViewBindingFragment<FragmentQueueBinding>(), QueueItemListener {
     private val playbackModel: PlaybackViewModel by androidActivityViewModels()
-    private var queueAdapter = QueueAdapter(this)
+    private val queueAdapter = QueueAdapter(this)
-    private var touchHelper: ItemTouchHelper? = null
+    private val touchHelper: ItemTouchHelper by lifecycleObject {
-    private var callback: QueueDragCallback? = null
+        ItemTouchHelper(QueueDragCallback(playbackModel))
+    }
 
     override fun onCreateBinding(inflater: LayoutInflater) = FragmentQueueBinding.inflate(inflater)
 
@@ -48,7 +48,7 @@ class QueueFragment : ViewBindingFragment<FragmentQueueBinding>(), QueueItemList
 
         binding.queueRecycler.apply {
             adapter = queueAdapter
-            requireTouchHelper().attachToRecyclerView(this)
+            touchHelper.attachToRecyclerView(this)
         }
 
         // --- VIEWMODEL SETUP ----
@@ -59,12 +59,10 @@ class QueueFragment : ViewBindingFragment<FragmentQueueBinding>(), QueueItemList
     override fun onDestroyBinding(binding: FragmentQueueBinding) {
         super.onDestroyBinding(binding)
         binding.queueRecycler.adapter = null
-        touchHelper = null
-        callback = null
     }
 
     override fun onPickUp(viewHolder: RecyclerView.ViewHolder) {
-        requireTouchHelper().startDrag(viewHolder)
+        touchHelper.startDrag(viewHolder)
     }
 
     private fun updateQueue(queue: List<Song>) {
@@ -75,17 +73,4 @@ class QueueFragment : ViewBindingFragment<FragmentQueueBinding>(), QueueItemList
 
         queueAdapter.data.submitList(queue.toMutableList())
     }
-
-    private fun requireTouchHelper(): ItemTouchHelper {
-        requireAttached()
-        val instance = touchHelper
-        if (instance != null) {
-            return instance
-        }
-        val newCallback = QueueDragCallback(playbackModel)
-        val newInstance = ItemTouchHelper(newCallback)
-        callback = newCallback
-        touchHelper = newInstance
-        return newInstance
-    }
 }

app/src/main/java/org/oxycblt/auxio/playback/replaygain/PreAmpCustomizeDialog.kt

@@ -26,8 +26,8 @@ import org.oxycblt.auxio.BuildConfig
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.DialogPreAmpBinding
 import org.oxycblt.auxio.settings.Settings
-import org.oxycblt.auxio.settings.settings
 import org.oxycblt.auxio.ui.ViewBindingDialogFragment
+import org.oxycblt.auxio.util.context
 import org.oxycblt.auxio.util.textSafe
 
 /**
@@ -35,7 +35,7 @@ import org.oxycblt.auxio.util.textSafe
  * @author OxygenCobalt
  */
 class PreAmpCustomizeDialog : ViewBindingDialogFragment<DialogPreAmpBinding>() {
-    private val settings: Settings by settings()
+    private val settings: Settings by lifecycleObject { binding -> Settings(binding.context) }
 
     override fun onCreateBinding(inflater: LayoutInflater) = DialogPreAmpBinding.inflate(inflater)
 

app/src/main/java/org/oxycblt/auxio/search/SearchFragment.kt

@@ -37,17 +37,16 @@ import org.oxycblt.auxio.music.Music
 import org.oxycblt.auxio.music.MusicParent
 import org.oxycblt.auxio.music.Song
 import org.oxycblt.auxio.settings.Settings
-import org.oxycblt.auxio.settings.settings
 import org.oxycblt.auxio.ui.Header
 import org.oxycblt.auxio.ui.Item
 import org.oxycblt.auxio.ui.MenuFragment
 import org.oxycblt.auxio.ui.MenuItemListener
 import org.oxycblt.auxio.util.androidViewModels
 import org.oxycblt.auxio.util.applySpans
+import org.oxycblt.auxio.util.context
 import org.oxycblt.auxio.util.getSystemServiceSafe
 import org.oxycblt.auxio.util.launch
 import org.oxycblt.auxio.util.logW
-import org.oxycblt.auxio.util.requireAttached
 
 /**
  * A [Fragment] that allows for the searching of the entire music library.
@@ -59,8 +58,11 @@ class SearchFragment :
     private val searchModel: SearchViewModel by androidViewModels()
 
     private val searchAdapter = SearchAdapter(this)
-    private val settings: Settings by settings()
+    private val settings: Settings by lifecycleObject { binding -> Settings(binding.context) }
-    private var imm: InputMethodManager? = null
+    private val imm: InputMethodManager by lifecycleObject { binding ->
+        binding.context.getSystemServiceSafe(InputMethodManager::class)
+    }
+
     private var launchedKeyboard = false
 
     override fun onCreateBinding(inflater: LayoutInflater) = FragmentSearchBinding.inflate(inflater)
@@ -70,7 +72,7 @@ class SearchFragment :
             menu.findItem(searchModel.filterMode?.itemId ?: R.id.option_filter_all).isChecked = true
 
             setNavigationOnClickListener {
-                requireImm().hide()
+                imm.hide()
                 findNavController().navigateUp()
             }
 
@@ -86,9 +88,7 @@ class SearchFragment :
             if (!launchedKeyboard) {
                 // Auto-open the keyboard when this view is shown
                 requestFocus()
-                postDelayed(200) {
+                postDelayed(200) { imm.showSoftInput(this, InputMethodManager.SHOW_IMPLICIT) }
-                    requireImm().showSoftInput(this, InputMethodManager.SHOW_IMPLICIT)
-                }
 
                 launchedKeyboard = true
             }
@@ -108,7 +108,6 @@ class SearchFragment :
     override fun onDestroyBinding(binding: FragmentSearchBinding) {
         binding.searchToolbar.setOnMenuItemClickListener(null)
         binding.searchRecycler.adapter = null
-        imm = null
     }
 
     override fun onMenuItemClick(item: MenuItem): Boolean {
@@ -166,18 +165,7 @@ class SearchFragment :
                     else -> return
                 })
 
-        requireImm().hide()
+        imm.hide()
-    }
-
-    private fun requireImm(): InputMethodManager {
-        requireAttached()
-        val instance = imm
-        if (instance != null) {
-            return instance
-        }
-        val newInstance = requireContext().getSystemServiceSafe(InputMethodManager::class)
-        imm = newInstance
-        return newInstance
     }
 
     private fun InputMethodManager.hide() {

app/src/main/java/org/oxycblt/auxio/settings/Settings.kt

@@ -22,12 +22,7 @@ import android.content.SharedPreferences
 import android.os.storage.StorageManager
 import androidx.appcompat.app.AppCompatDelegate
 import androidx.core.content.edit
-import androidx.fragment.app.Fragment
-import androidx.lifecycle.DefaultLifecycleObserver
-import androidx.lifecycle.LifecycleOwner
 import androidx.preference.PreferenceManager
-import kotlin.properties.ReadOnlyProperty
-import kotlin.reflect.KProperty
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.home.tabs.Tab
 import org.oxycblt.auxio.music.Directory
@@ -39,55 +34,14 @@ import org.oxycblt.auxio.ui.DisplayMode
 import org.oxycblt.auxio.ui.Sort
 import org.oxycblt.auxio.ui.accent.Accent
 import org.oxycblt.auxio.util.logD
-import org.oxycblt.auxio.util.requireAttached
 import org.oxycblt.auxio.util.unlikelyToBeNull
 
-/**
- * Shortcut delegate in order to receive a [Settings] that will be created/destroyed
- * in each lifecycle.
- *
- * TODO: Replace with generalized method
- */
-fun Fragment.settings(): ReadOnlyProperty<Fragment, Settings> =
-    object : ReadOnlyProperty<Fragment, Settings>, DefaultLifecycleObserver {
-        private var settings: Settings? = null
-
-        init {
-            lifecycle.addObserver(
-                object : DefaultLifecycleObserver {
-                    override fun onCreate(owner: LifecycleOwner) {
-                        viewLifecycleOwnerLiveData.observe(this@settings) { viewLifecycleOwner ->
-                            viewLifecycleOwner.lifecycle.addObserver(this)
-                        }
-                    }
-                })
-        }
-
-        override fun getValue(thisRef: Fragment, property: KProperty<*>): Settings {
-            requireAttached()
-
-            val currentSettings = settings
-            if (currentSettings != null) {
-                return currentSettings
-            }
-
-            val newSettings = Settings(requireContext())
-            settings = newSettings
-            return newSettings
-        }
-
-        override fun onDestroy(owner: LifecycleOwner) {
-            settings?.release()
-            settings = null
-        }
-    }
-
 /**
  * Auxio's settings.
  *
- * This object wraps [SharedPreferences] in a type-safe manner, allowing access to all of the
+ * This object wraps [SharedPreferences] in a type-safe manner, allowing access to all of the major
- * major settings that Auxio uses. Mutability is determined by use, as some values are written
+ * settings that Auxio uses. Mutability is determined by use, as some values are written by
- * by PreferenceManager and others are written by Auxio's code.
+ * PreferenceManager and others are written by Auxio's code.
  *
  * @author OxygenCobalt
  */

app/src/main/java/org/oxycblt/auxio/settings/SettingsListFragment.kt

@@ -56,7 +56,6 @@ import org.oxycblt.auxio.util.showToast
 @Suppress("UNUSED")
 class SettingsListFragment : PreferenceFragmentCompat() {
     private val playbackModel: PlaybackViewModel by androidActivityViewModels()
-    private val settings: Settings by settings()
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
@@ -134,6 +133,8 @@ class SettingsListFragment : PreferenceFragmentCompat() {
 
     /** Recursively handle a preference, doing any specific actions on it. */
     private fun recursivelyHandlePreference(preference: Preference) {
+        val settings = Settings(requireContext())
+
         if (!preference.isVisible) return
 
         if (preference is PreferenceCategory) {

app/src/main/java/org/oxycblt/auxio/settings/ui/WrappedDialogPreference.kt

@@ -22,8 +22,8 @@ import android.util.AttributeSet
 import androidx.preference.DialogPreference
 
 /**
- * Wraps [DialogPreference] as to make it type-distinct from other preferences while also
+ * Wraps [DialogPreference] as to make it type-distinct from other preferences while also making it
- * making it possible to use in a PreferenceScreen.
+ * possible to use in a PreferenceScreen.
  */
 class WrappedDialogPreference
 @JvmOverloads

app/src/main/java/org/oxycblt/auxio/ui/ViewBindingDialogFragment.kt

@@ -23,53 +23,73 @@ import android.view.View
 import android.view.ViewGroup
 import androidx.appcompat.app.AlertDialog
 import androidx.fragment.app.DialogFragment
+import androidx.fragment.app.Fragment
 import androidx.viewbinding.ViewBinding
 import com.google.android.material.dialog.MaterialAlertDialogBuilder
+import kotlin.properties.ReadOnlyProperty
+import kotlin.reflect.KProperty
 import org.oxycblt.auxio.util.logD
+import org.oxycblt.auxio.util.unlikelyToBeNull
 
 /**
  * A dialog fragment enabling ViewBinding inflation and usage across the dialog fragment lifecycle.
  * @author OxygenCobalt
  */
-abstract class ViewBindingDialogFragment<T : ViewBinding> : DialogFragment() {
+abstract class ViewBindingDialogFragment<VB : ViewBinding> : DialogFragment() {
-    private var _binding: T? = null
+    private var _binding: VB? = null
-
+    private var lifecycleObjects = mutableListOf<LifecycleObject<VB, *>>()
-    /**
-     * Inflate the binding from the given [inflater]. This should usually be done by the binding
-     * implementation's inflate function.
-     */
-    protected abstract fun onCreateBinding(inflater: LayoutInflater): T
 
     /** Called during [onCreateDialog]. Dialog elements should be configured here. */
     protected open fun onConfigDialog(builder: AlertDialog.Builder) {}
 
+    /**
+     * Inflate the binding from the given [inflater]. This should usually be done by the binding
+     * implementation's inflate function.
+     */
+    protected abstract fun onCreateBinding(inflater: LayoutInflater): VB
+
     /**
      * Called during [onViewCreated] when the binding was successfully inflated and set as the view.
      * This is where view setup should occur.
      */
-    protected open fun onBindingCreated(binding: T, savedInstanceState: Bundle?) {}
+    protected open fun onBindingCreated(binding: VB, savedInstanceState: Bundle?) {}
 
     /**
      * Called during [onDestroyView] when the binding should be destroyed and all callbacks or
      * leaking elements be released.
      */
-    protected open fun onDestroyBinding(binding: T) {}
+    protected open fun onDestroyBinding(binding: VB) {}
 
     /** Maybe get the binding. This will be null outside of the fragment view lifecycle. */
-    protected val binding: T?
+    protected val binding: VB?
         get() = _binding
 
     /**
      * Get the binding under the assumption that the fragment has a view at this state in the
      * lifecycle. This will throw an exception if the fragment is not in a valid lifecycle.
      */
-    protected fun requireBinding(): T {
+    protected fun requireBinding(): VB {
         return requireNotNull(_binding) {
             "ViewBinding was available. Fragment should be a valid state " +
                 "right now, but instead it was ${lifecycle.currentState}"
         }
     }
 
+    fun <T> lifecycleObject(create: (VB) -> T): ReadOnlyProperty<Fragment, T> {
+        lifecycleObjects.add(LifecycleObject(null, create))
+
+        return object : ReadOnlyProperty<Fragment, T> {
+            private val objIdx = lifecycleObjects.lastIndex
+
+            @Suppress("UNCHECKED_CAST")
+            override fun getValue(thisRef: Fragment, property: KProperty<*>) =
+                requireNotNull(lifecycleObjects[objIdx].data) {
+                    "Cannot access lifecycle object when view does not exist"
+                }
+                    as T
+        }
+    }
+
     override fun onCreateView(
         inflater: LayoutInflater,
         container: ViewGroup?,
@@ -84,6 +104,8 @@ abstract class ViewBindingDialogFragment<T : ViewBinding> : DialogFragment() {
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
+        val binding = unlikelyToBeNull(_binding)
+        lifecycleObjects.forEach { it.populate(binding) }
         onBindingCreated(requireBinding(), savedInstanceState)
         (requireDialog() as AlertDialog).setView(view)
         logD("Fragment created")
@@ -91,8 +113,19 @@ abstract class ViewBindingDialogFragment<T : ViewBinding> : DialogFragment() {
 
     override fun onDestroyView() {
         super.onDestroyView()
-        onDestroyBinding(requireBinding())
+        onDestroyBinding(unlikelyToBeNull(_binding))
+        lifecycleObjects.forEach { it.clear() }
         _binding = null
         logD("Fragment destroyed")
     }
+
+    private data class LifecycleObject<VB, T>(var data: T?, val create: (VB) -> T) {
+        fun populate(binding: VB) {
+            data = create(binding)
+        }
+
+        fun clear() {
+            data = null
+        }
+    }
 }

app/src/main/java/org/oxycblt/auxio/ui/ViewBindingFragment.kt

@@ -23,48 +23,71 @@ import android.view.View
 import android.view.ViewGroup
 import androidx.fragment.app.Fragment
 import androidx.viewbinding.ViewBinding
+import kotlin.properties.ReadOnlyProperty
+import kotlin.reflect.KProperty
 import org.oxycblt.auxio.util.logD
+import org.oxycblt.auxio.util.unlikelyToBeNull
 
 /**
  * A fragment enabling ViewBinding inflation and usage across the fragment lifecycle.
  * @author OxygenCobalt
  */
-abstract class ViewBindingFragment<T : ViewBinding> : Fragment() {
+abstract class ViewBindingFragment<VB : ViewBinding> : Fragment() {
-    private var _binding: T? = null
+    private var _binding: VB? = null
+    private var lifecycleObjects = mutableListOf<LifecycleObject<VB, *>>()
 
     /**
      * Inflate the binding from the given [inflater]. This should usually be done by the binding
      * implementation's inflate function.
      */
-    protected abstract fun onCreateBinding(inflater: LayoutInflater): T
+    protected abstract fun onCreateBinding(inflater: LayoutInflater): VB
 
     /**
      * Called during [onViewCreated] when the binding was successfully inflated and set as the view.
      * This is where view setup should occur.
      */
-    protected open fun onBindingCreated(binding: T, savedInstanceState: Bundle?) {}
+    protected open fun onBindingCreated(binding: VB, savedInstanceState: Bundle?) {}
 
     /**
      * Called during [onDestroyView] when the binding should be destroyed and all callbacks or
      * leaking elements be released.
      */
-    protected open fun onDestroyBinding(binding: T) {}
+    protected open fun onDestroyBinding(binding: VB) {}
 
     /** Maybe get the binding. This will be null outside of the fragment view lifecycle. */
-    protected val binding: T?
+    protected val binding: VB?
         get() = _binding
 
     /**
      * Get the binding under the assumption that the fragment has a view at this state in the
      * lifecycle. This will throw an exception if the fragment is not in a valid lifecycle.
      */
-    protected fun requireBinding(): T {
+    protected fun requireBinding(): VB {
         return requireNotNull(_binding) {
             "ViewBinding was available. Fragment should be a valid state " +
                 "right now, but instead it was ${lifecycle.currentState}"
         }
     }
 
+    /**
+     * Shortcut to create a member bound to the lifecycle of this fragment. This is automatically
+     * populated in onBindingCreated, and destroyed in onDestroyBinding.
+     */
+    fun <T> lifecycleObject(create: (VB) -> T): ReadOnlyProperty<Fragment, T> {
+        lifecycleObjects.add(LifecycleObject(null, create))
+
+        return object : ReadOnlyProperty<Fragment, T> {
+            private val objIdx = lifecycleObjects.lastIndex
+
+            @Suppress("UNCHECKED_CAST")
+            override fun getValue(thisRef: Fragment, property: KProperty<*>) =
+                requireNotNull(lifecycleObjects[objIdx].data) {
+                    "Cannot access lifecycle object when view does not exist"
+                }
+                    as T
+        }
+    }
+
     override fun onCreateView(
         inflater: LayoutInflater,
         container: ViewGroup?,
@@ -73,14 +96,27 @@ abstract class ViewBindingFragment<T : ViewBinding> : Fragment() {
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
-        onBindingCreated(requireBinding(), savedInstanceState)
+        val binding = unlikelyToBeNull(_binding)
+        lifecycleObjects.forEach { it.populate(binding) }
+        onBindingCreated(binding, savedInstanceState)
         logD("Fragment created")
     }
 
     override fun onDestroyView() {
         super.onDestroyView()
-        onDestroyBinding(requireBinding())
+        onDestroyBinding(unlikelyToBeNull(_binding))
+        lifecycleObjects.forEach { it.clear() }
         _binding = null
         logD("Fragment destroyed")
     }
+
+    private data class LifecycleObject<VB, T>(var data: T?, val create: (VB) -> T) {
+        fun populate(binding: VB) {
+            data = create(binding)
+        }
+
+        fun clear() {
+            data = null
+        }
+    }
 }

app/src/main/java/org/oxycblt/auxio/ui/accent/AccentCustomizeDialog.kt

@@ -24,8 +24,8 @@ import org.oxycblt.auxio.BuildConfig
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.DialogAccentBinding
 import org.oxycblt.auxio.settings.Settings
-import org.oxycblt.auxio.settings.settings
 import org.oxycblt.auxio.ui.ViewBindingDialogFragment
+import org.oxycblt.auxio.util.context
 import org.oxycblt.auxio.util.logD
 import org.oxycblt.auxio.util.unlikelyToBeNull
 
@@ -36,7 +36,7 @@ import org.oxycblt.auxio.util.unlikelyToBeNull
 class AccentCustomizeDialog :
     ViewBindingDialogFragment<DialogAccentBinding>(), AccentAdapter.Listener {
     private var accentAdapter = AccentAdapter(this)
-    private val settings: Settings by settings()
+    private val settings: Settings by lifecycleObject { binding -> Settings(binding.context) }
 
     override fun onCreateBinding(inflater: LayoutInflater) = DialogAccentBinding.inflate(inflater)
 

app/src/main/java/org/oxycblt/auxio/util/FrameworkUtil.kt

@@ -157,11 +157,6 @@ val RecyclerView.canScroll: Boolean
 val @receiver:ColorRes Int.stateList
     get() = ColorStateList.valueOf(this)
 
-/** Require the fragment is attached to an activity. */
-fun Fragment.requireAttached() {
-    check(!isDetached) { "Fragment is detached from activity" }
-}
-
 /**
  * Launches [block] in a lifecycle-aware coroutine once [state] is reached. This is primarily a
  * shortcut intended to correctly launch a co-routine on a fragment in a way that won't cause