Simplified/fixed scroll to top

app/src/main/java/eu/faircode/email/AdapterMessage.java

@@ -3658,29 +3658,7 @@ public class AdapterMessage extends RecyclerView.Adapter<AdapterMessage.ViewHold
         this.differ.addPagedListListener(new AsyncPagedListDiffer.PagedListListener<TupleMessageEx>() {
             @Override
             public void onCurrentListChanged(@Nullable PagedList<TupleMessageEx> previousList, @Nullable PagedList<TupleMessageEx> currentList) {
-                boolean autoscroll =
-                        (viewType == AdapterMessage.ViewType.THREAD ||
-                                (viewType != ViewType.SEARCH &&
-                                        prefs.getBoolean("autoscroll", true)));
-
-                int prev = 0;
-                if (autoscroll && previousList != null)
-                    for (int i = 0; i < previousList.size(); i++) {
-                        TupleMessageEx message = previousList.get(i);
-                        if (message != null && !message.ui_seen && !message.ui_ignored && !message.duplicate)
-                            prev++;
-                    }
-
-                int cur = 0;
-                if (autoscroll && currentList != null)
-                    for (int i = 0; i < currentList.size(); i++) {
-                        TupleMessageEx message = currentList.get(i);
-                        if (message != null && !message.ui_seen && !message.ui_ignored && !message.duplicate)
-                            cur++;
-                    }
-
-                if (gotoTop ||
-                        (previousList != null && currentList != null && cur > prev)) {
+                if (gotoTop) {
                     gotoTop = false;
                     properties.scrollTo(0);
                 }

app/src/main/java/eu/faircode/email/FragmentMessages.java

@@ -3175,6 +3175,8 @@ public class FragmentMessages extends FragmentBase implements SharedPreferences.
     };
 
     private Observer<PagedList<TupleMessageEx>> observer = new Observer<PagedList<TupleMessageEx>>() {
+        private List<Long> ids = new ArrayList<>();
+
         @Override
         public void onChanged(@Nullable PagedList<TupleMessageEx> messages) {
             if (messages == null)
@@ -3184,6 +3186,27 @@ public class FragmentMessages extends FragmentBase implements SharedPreferences.
                 if (handleThreadActions(messages))
                     return;
 
+            if (viewType == AdapterMessage.ViewType.THREAD)
+                adapter.gotoTop();
+            else if (viewType != AdapterMessage.ViewType.SEARCH) {
+                SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getContext());
+                boolean autoscroll = prefs.getBoolean("autoscroll", true);
+                if (autoscroll) {
+                    boolean gotoTop = false;
+                    for (int i = 0; i < messages.size(); i++) {
+                        TupleMessageEx message = messages.get(i);
+                        if (message != null && !ids.contains(message.id)) {
+                            ids.add(message.id);
+                            if (!message.ui_seen)
+                                gotoTop = true;
+                        }
+                    }
+
+                    if (gotoTop)
+                        adapter.gotoTop();
+                }
+            }
+
             Log.i("Submit messages=" + messages.size());
             adapter.submitList(messages);