From ec8793c6fe3b7131cbf77f5de98a26a816d71a0f Mon Sep 17 00:00:00 2001
From: Greyson Parrelli <greyson@signal.org>
Date: Wed, 9 Dec 2020 14:39:22 -0500
Subject: [PATCH] Fix rendering issue when deleting the last message in a
 conversation.

---
 .../securesms/conversation/ConversationFragment.java       | 7 +++++--
 .../java/org/signal/paging/FixedSizePagingController.java  | 6 ++++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationFragment.java b/app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationFragment.java
index 158df5b8a..a3a583302 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationFragment.java
+++ b/app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationFragment.java
@@ -250,8 +250,11 @@ public class ConversationFragment extends LoggingFragment {
     this.messageCountsViewModel = ViewModelProviders.of(requireActivity()).get(MessageCountsViewModel.class);
     this.conversationViewModel  = ViewModelProviders.of(requireActivity(), new ConversationViewModel.Factory()).get(ConversationViewModel.class);
 
-    conversationViewModel.getMessages().observe(this, list -> {
-      getListAdapter().submitList(list);
+    conversationViewModel.getMessages().observe(this, messages -> {
+      ConversationAdapter adapter = getListAdapter();
+      if (adapter != null) {
+        getListAdapter().submitList(messages);
+      }
     });
 
     conversationViewModel.getConversationMetadata().observe(this, this::presentConversationMetadata);
diff --git a/paging/lib/src/main/java/org/signal/paging/FixedSizePagingController.java b/paging/lib/src/main/java/org/signal/paging/FixedSizePagingController.java
index a8e5d6d23..4587997e3 100644
--- a/paging/lib/src/main/java/org/signal/paging/FixedSizePagingController.java
+++ b/paging/lib/src/main/java/org/signal/paging/FixedSizePagingController.java
@@ -6,6 +6,7 @@ import androidx.lifecycle.MutableLiveData;
 import org.signal.core.util.concurrent.SignalExecutors;
 import org.signal.core.util.logging.Log;
 
+import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.Executor;
 
@@ -57,6 +58,11 @@ class FixedSizePagingController<E> implements PagingController {
       return;
     }
 
+    if (loadState.size() == 0) {
+      liveData.postValue(Collections.emptyList());
+      return;
+    }
+
     int leftPageBoundary  = (aroundIndex / config.pageSize()) * config.pageSize();
     int rightPageBoundary = leftPageBoundary + config.pageSize();
     int buffer            = config.bufferPages() * config.pageSize();