Fix lifecycle state for media preview.

After a fragment is destroyed, the media remains loaded in the view model, and it is up to the re-created fragment to take that loaded data and make it ready to be viewed.

app/src/main/java/org/thoughtcrime/securesms/mediapreview/MediaPreviewV2Fragment.kt

@@ -292,10 +292,10 @@ class MediaPreviewV2Fragment : Fragment(R.layout.fragment_media_preview_v2), Med
     ViewCompat.setOnApplyWindowInsetsListener(viewToAnchor) { view: View, windowInsetsCompat: WindowInsetsCompat ->
       val layoutParams = view.layoutParams as MarginLayoutParams
       layoutParams.setMargins(
-        windowInsetsCompat.getSystemWindowInsetLeft(),
+        windowInsetsCompat.systemWindowInsetLeft,
         layoutParams.topMargin,
-        windowInsetsCompat.getSystemWindowInsetRight(),
-        windowInsetsCompat.getSystemWindowInsetBottom()
+        windowInsetsCompat.systemWindowInsetRight,
+        windowInsetsCompat.systemWindowInsetBottom
       )
       view.layoutParams = layoutParams
       windowInsetsCompat
@@ -440,6 +440,11 @@ class MediaPreviewV2Fragment : Fragment(R.layout.fragment_media_preview_v2), Med
     getMediaPreviewFragmentFromChildFragmentManager(binding.mediaPager.currentItem)?.pause()
   }
 
+  override fun onDestroyView() {
+    super.onDestroyView()
+    viewModel.onDestroyView()
+  }
+
   companion object {
     const val ARGS_KEY: String = "args"
 

app/src/main/java/org/thoughtcrime/securesms/mediapreview/MediaPreviewV2ViewModel.kt

@@ -26,8 +26,7 @@ class MediaPreviewV2ViewModel : ViewModel() {
 
   fun fetchAttachments(startingAttachmentId: AttachmentId, threadId: Long, sorting: MediaDatabase.Sorting, forceRefresh: Boolean = false) {
     if (store.state.loadState == MediaPreviewV2State.LoadState.INIT || forceRefresh) {
-      disposables += store.update(repository.getAttachments(startingAttachmentId, threadId, sorting)) {
-        result: MediaPreviewRepository.Result, oldState: MediaPreviewV2State ->
+      disposables += store.update(repository.getAttachments(startingAttachmentId, threadId, sorting)) { result: MediaPreviewRepository.Result, oldState: MediaPreviewV2State ->
         if (oldState.leftIsRecent) {
           oldState.copy(
             position = result.initialPosition,
@@ -76,4 +75,10 @@ class MediaPreviewV2ViewModel : ViewModel() {
     disposables.dispose()
     store.dispose()
   }
+
+  fun onDestroyView() {
+    store.update { oldState ->
+      oldState.copy(loadState = MediaPreviewV2State.LoadState.DATA_LOADED)
+    }
+  }
 }