fix: Fix Breadcrumbs disappearing when resuming the folders tab

app/src/main/java/code/name/monkey/retromusic/fragments/folder/FoldersFragment.kt

@@ -55,6 +55,7 @@ import code.name.monkey.retromusic.helper.menu.SongMenuHelper
 import code.name.monkey.retromusic.helper.menu.SongsMenuHelper
 import code.name.monkey.retromusic.interfaces.ICallbacks
 import code.name.monkey.retromusic.interfaces.IMainActivityFragmentCallbacks
+import code.name.monkey.retromusic.interfaces.IScrollHelper
 import code.name.monkey.retromusic.misc.UpdateToastMediaScannerCompletionListener
 import code.name.monkey.retromusic.misc.WrappedAsyncTaskLoader
 import code.name.monkey.retromusic.model.Song
@@ -64,8 +65,8 @@ import code.name.monkey.retromusic.util.PreferenceUtil.startDirectory
 import code.name.monkey.retromusic.util.ThemedFastScroller.create
 import code.name.monkey.retromusic.util.getExternalStorageDirectory
 import code.name.monkey.retromusic.util.getExternalStoragePublicDirectory
+import code.name.monkey.retromusic.views.BreadCrumbLayout
 import code.name.monkey.retromusic.views.BreadCrumbLayout.Crumb
-import code.name.monkey.retromusic.views.BreadCrumbLayout.SavedStateWrapper
 import code.name.monkey.retromusic.views.BreadCrumbLayout.SelectionCallback
 import com.google.android.material.snackbar.Snackbar
 import com.google.android.material.transition.MaterialFadeThrough
@@ -81,7 +82,7 @@ import java.util.LinkedList
 
 class FoldersFragment : AbsMainActivityFragment(R.layout.fragment_folder),
     IMainActivityFragmentCallbacks, SelectionCallback, ICallbacks,
-    LoaderManager.LoaderCallbacks<List<File>>, StorageClickListener {
+    LoaderManager.LoaderCallbacks<List<File>>, StorageClickListener, IScrollHelper {
     private var _binding: FragmentFolderBinding? = null
     private val binding get() = _binding!!
 
@@ -124,17 +125,6 @@ class FoldersFragment : AbsMainActivityFragment(R.layout.fragment_folder),
                     }
                 }
             })
-    }
-
-    private fun setUpTitle() {
-        toolbar.setNavigationOnClickListener {
-            findNavController().navigate(R.id.action_search, null, navOptions)
-        }
-        binding.appBarLayout.title = resources.getString(R.string.folders)
-    }
-
-    override fun onActivityCreated(savedInstanceState: Bundle?) {
-        super.onActivityCreated(savedInstanceState)
         if (savedInstanceState == null) {
             switchToFileAdapter()
             setCrumb(
@@ -144,11 +134,29 @@ class FoldersFragment : AbsMainActivityFragment(R.layout.fragment_folder),
                 true
             )
         } else {
-            binding.breadCrumbs.restoreFromStateWrapper(BundleCompat.getParcelable(savedInstanceState, CRUMBS, SavedStateWrapper::class.java))
+            binding.breadCrumbs.restoreFromStateWrapper(
+                BundleCompat.getParcelable(
+                    savedInstanceState,
+                    CRUMBS,
+                    BreadCrumbLayout.SavedStateWrapper::class.java
+                )
+            )
             LoaderManager.getInstance(this).initLoader(LOADER_ID, null, this)
         }
     }
 
+    override fun onSaveInstanceState(outState: Bundle) {
+        super.onSaveInstanceState(outState)
+        outState.putParcelable(CRUMBS, binding.breadCrumbs.stateWrapper)
+    }
+
+    private fun setUpTitle() {
+        toolbar.setNavigationOnClickListener {
+            findNavController().navigate(R.id.action_search, null, navOptions)
+        }
+        binding.appBarLayout.title = resources.getString(R.string.folders)
+    }
+
     override fun onPause() {
         super.onPause()
         saveScrollPosition()
@@ -417,13 +425,11 @@ class FoldersFragment : AbsMainActivityFragment(R.layout.fragment_folder),
     }
 
     private fun saveScrollPosition() {
-        val crumb = activeCrumb
+        activeCrumb?.scrollPosition =
-        if (crumb != null) {
+            (binding.recyclerView.layoutManager as LinearLayoutManager).findFirstVisibleItemPosition()
-            crumb.scrollPosition =
-                (binding.recyclerView.layoutManager as LinearLayoutManager?)!!.findFirstVisibleItemPosition()
-        }
     }
 
+
     private fun scanPaths(toBeScanned: Array<String?>) {
         if (activity == null) {
             return
@@ -483,8 +489,8 @@ class FoldersFragment : AbsMainActivityFragment(R.layout.fragment_folder),
         adapter?.swapDataSet(files)
         val crumb = activeCrumb
         if (crumb != null) {
-            (binding.recyclerView.layoutManager as LinearLayoutManager?)
+            (binding.recyclerView.layoutManager as LinearLayoutManager)
-                ?.scrollToPositionWithOffset(crumb.scrollPosition, 0)
+                .scrollToPositionWithOffset(crumb.scrollPosition, 0)
         }
     }
 
@@ -548,7 +554,7 @@ class FoldersFragment : AbsMainActivityFragment(R.layout.fragment_folder),
         }
     }
 
-    suspend fun listSongs(
+    private suspend fun listSongs(
         context: Context,
         files: List<File?>,
         fileFilter: FileFilter,
@@ -578,6 +584,11 @@ class FoldersFragment : AbsMainActivityFragment(R.layout.fragment_folder),
         )
     }
 
+    override fun scrollToTop() {
+        binding.recyclerView.scrollToPosition(0)
+        binding.appBarLayout.setExpanded(true, true)
+    }
+
     private fun switchToFileAdapter() {
         adapter = SongFileAdapter(mainActivity, LinkedList(), R.layout.item_list, this)
         adapter!!.registerAdapterDataObserver(