Make group subtitles auto-update as names change.

app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationTitleView.java

@@ -15,8 +15,6 @@ import androidx.annotation.Nullable;
 import androidx.constraintlayout.widget.ConstraintLayout;
 import androidx.core.content.ContextCompat;
 
-import com.annimon.stream.Collectors;
-import com.annimon.stream.Stream;
 import com.bumptech.glide.RequestManager;
 
 import org.thoughtcrime.securesms.R;
@@ -176,6 +174,11 @@ public class ConversationTitleView extends ConstraintLayout {
     updateVerifiedSubtitleVisibility();
   }
 
+  public void setGroupRecipientSubtitle(@Nullable String members) {
+    this.subtitle.setText(members);
+    updateSubtitleVisibility();
+  }
+
   private void setComposeTitle() {
     this.title.setText(R.string.ConversationActivity_compose_message);
     this.subtitle.setText(null);
@@ -190,15 +193,6 @@ public class ConversationTitleView extends ConstraintLayout {
 
   private void setGroupRecipientTitle(@NonNull Recipient recipient) {
     this.title.setText(recipient.getDisplayName(getContext()));
-    this.subtitle.setText(Stream.of(recipient.getParticipantIds())
-                                .limit(10)
-                                .map(Recipient::resolved)
-                                .sorted((a, b) -> Boolean.compare(a.isSelf(), b.isSelf()))
-                                .map(r -> r.isSelf() ? getResources().getString(R.string.ConversationTitleView_you)
-                                                     : r.getDisplayName(getContext()))
-                                .collect(Collectors.joining(", ")));
-
-    updateSubtitleVisibility();
   }
 
   private void setSelfTitle() {

app/src/main/java/org/thoughtcrime/securesms/conversation/v2/ConversationFragment.kt

@@ -581,6 +581,7 @@ class ConversationFragment :
     presentWallpaper(args.wallpaper)
     presentChatColors(args.chatColors)
     presentConversationTitle(viewModel.recipientSnapshot)
+    presentGroupConversationSubtitle(createGroupSubtitleString(viewModel.titleViewParticipantsSnapshot))
     presentActionBarMenu()
     presentStoryRing()
 
@@ -865,6 +866,10 @@ class ConversationFragment :
 
   //endregion
 
+  private fun createGroupSubtitleString(members: List<Recipient>): String {
+    return members.joinToString(", ") { r -> if (r.isSelf) getString(R.string.ConversationTitleView_you) else r.getDisplayName(requireContext()) }
+  }
+
   private fun observeConversationThread() {
     var firstRender = true
     disposables += viewModel
@@ -924,6 +929,12 @@ class ConversationFragment :
       .distinctUntilChanged { r1, r2 -> r1 === r2 || r1.hasSameContent(r2) }
       .subscribeBy(onNext = this::onRecipientChanged)
 
+    disposables += viewModel.titleViewParticipants
+      .map { createGroupSubtitleString(it) }
+      .distinctUntilChanged()
+      .observeOn(AndroidSchedulers.mainThread())
+      .subscribeBy(onNext = this::presentGroupConversationSubtitle)
+
     disposables += viewModel.scrollButtonState
       .subscribeBy(onNext = this::presentScrollButtons)
 
@@ -1315,6 +1326,17 @@ class ConversationFragment :
     }
   }
 
+  private fun presentGroupConversationSubtitle(subtitle: String) {
+    val titleView = binding.conversationTitleView.root
+
+    if (subtitle.isBlank()) {
+      titleView.setGroupRecipientSubtitle(null)
+      return
+    }
+
+    titleView.setGroupRecipientSubtitle(subtitle)
+  }
+
   private fun presentConversationTitle(recipient: Recipient?) {
     if (recipient == null) {
       return
@@ -1323,6 +1345,7 @@ class ConversationFragment :
     val titleView = binding.conversationTitleView.root
 
     titleView.setTitle(Glide.with(this), recipient)
+
     if (recipient.expiresInSeconds > 0) {
       titleView.showExpiring(recipient)
     } else {

app/src/main/java/org/thoughtcrime/securesms/conversation/v2/ConversationViewModel.kt

@@ -101,6 +101,17 @@ class ConversationViewModel(
     get() = scrollButtonStateStore.state.unreadCount
 
   val recipient: Observable<Recipient> = recipientRepository.conversationRecipient
+  val titleViewParticipants: Observable<List<Recipient>> = recipient.filter { it.isGroup }.switchMap { groupRecipient ->
+    val firstTenIds = groupRecipient.participantIds
+      .take(10)
+      .sortedBy { it == Recipient.self().id }
+
+    Observable.combineLatest(
+      firstTenIds.map { Recipient.observable(it) }
+    ) { objects ->
+      objects.toList() as List<Recipient>
+    }
+  }
 
   private val _conversationThreadState: Subject<ConversationThreadState> = BehaviorSubject.create()
   val conversationThreadState: Single<ConversationThreadState> = _conversationThreadState.firstOrError()
@@ -122,6 +133,10 @@ class ConversationViewModel(
   var recipientSnapshot: Recipient? = null
     private set
 
+  @Volatile
+  var titleViewParticipantsSnapshot: List<Recipient> = emptyList()
+    private set
+
   val isPushAvailable: Boolean
     get() = recipientSnapshot?.isRegistered == true && Recipient.self().isRegistered
 
@@ -167,6 +182,11 @@ class ConversationViewModel(
         recipientSnapshot = it
       }
 
+    disposables += titleViewParticipants
+      .subscribeBy {
+        titleViewParticipantsSnapshot = it
+      }
+
     val chatColorsDataObservable: Observable<ChatColorsDrawable.ChatColorsData> = Observable.combineLatest(
       recipient.map { it.chatColors }.distinctUntilChanged(),
       chatBounds.distinctUntilChanged()