Fix flashing when send/recv messages in a new conversation.

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

@@ -225,7 +225,7 @@ public class ConversationAdapter
       case MESSAGE_TYPE_HEADER:
         return new HeaderViewHolder(CachedInflater.from(parent.getContext()).inflate(R.layout.cursor_adapter_header_footer_view, parent, false));
       case MESSAGE_TYPE_FOOTER:
-        return new HeaderFooterViewHolder(CachedInflater.from(parent.getContext()).inflate(R.layout.cursor_adapter_header_footer_view, parent, false));
+        return new FooterViewHolder(CachedInflater.from(parent.getContext()).inflate(R.layout.cursor_adapter_header_footer_view, parent, false));
       default:
         throw new IllegalStateException("Cannot create viewholder for type: " + viewType);
     }
@@ -748,7 +748,7 @@ public class ConversationAdapter
     }
   }
 
-  public static class HeaderFooterViewHolder extends RecyclerView.ViewHolder {
+  public abstract static class HeaderFooterViewHolder extends RecyclerView.ViewHolder {
 
     private ViewGroup container;
 
@@ -777,6 +777,10 @@ public class ConversationAdapter
     }
   }
 
+  public static class FooterViewHolder extends HeaderFooterViewHolder {
+    FooterViewHolder(@NonNull View itemView) { super(itemView); }
+  }
+
   public static class HeaderViewHolder extends HeaderFooterViewHolder {
     HeaderViewHolder(@NonNull View itemView) {
       super(itemView);

app/src/main/java/org/thoughtcrime/securesms/conversation/mutiselect/ConversationItemAnimator.kt

@@ -45,7 +45,8 @@ class ConversationItemAnimator(
     if (viewHolder is ConversationAdapter.HeaderViewHolder &&
       !pendingSlideAnimations.containsKey(viewHolder) &&
       !slideAnimations.containsKey(viewHolder) &&
-      shouldPlayMessageAnimations()
+      shouldPlayMessageAnimations() &&
+      isParentFilled()
     ) {
       pendingSlideAnimations[viewHolder] = TweeningInfo(0f, viewHolder.itemView.height.toFloat())
       dispatchAnimationStarted(viewHolder)
@@ -71,7 +72,7 @@ class ConversationItemAnimator(
       return false
     }
 
-    if (operation == Operation.CHANGE && !isParentFilled() || slideAnimations.containsKey(viewHolder)) {
+    if (operation == Operation.CHANGE || slideAnimations.containsKey(viewHolder)) {
       dispatchAnimationFinished(viewHolder)
       return false
     }
@@ -100,8 +101,7 @@ class ConversationItemAnimator(
   }
 
   override fun animatePersistence(viewHolder: RecyclerView.ViewHolder, preLayoutInfo: ItemHolderInfo, postLayoutInfo: ItemHolderInfo): Boolean {
-    val isInMultiSelectMode = isInMultiSelectMode()
-    return if (!isInMultiSelectMode && shouldPlayMessageAnimations()) {
+    return if (!isInMultiSelectMode() && shouldPlayMessageAnimations() && isParentFilled()) {
       if (pendingSlideAnimations.contains(viewHolder) || slideAnimations.containsKey(viewHolder)) {
         dispatchAnimationFinished(viewHolder)
         false

app/src/main/java/org/thoughtcrime/securesms/giph/mp4/GiphyMp4ItemDecoration.kt

@@ -3,6 +3,7 @@ package org.thoughtcrime.securesms.giph.mp4
 import android.graphics.Canvas
 import androidx.core.view.children
 import androidx.recyclerview.widget.RecyclerView
+import org.thoughtcrime.securesms.conversation.ConversationAdapter
 import kotlin.math.min
 
 /**
@@ -21,8 +22,19 @@ class GiphyMp4ItemDecoration(val callback: GiphyMp4PlaybackController.Callback)
     if (parent.childCount == 0 || parent.canScrollVertically(-1) || parent.canScrollVertically(1)) {
       parent.translationY = 0f
     } else {
-      val childTop = parent.children.last().top
-      parent.translationY = min(0, -childTop).toFloat()
+      val footerViewHolder = parent.children
+        .map { parent.getChildViewHolder(it) }
+        .filterIsInstance(ConversationAdapter.FooterViewHolder::class.java)
+        .firstOrNull()
+
+      if (footerViewHolder == null) {
+        parent.translationY = 0f
+        return
+      }
+
+      val childTop = footerViewHolder.itemView.top
+      parent.translationY = min(0, -childTop).toFloat().also {
+      }
     }
   }
 }