Attempt to keep scroll position on rotating

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

@@ -264,6 +264,7 @@ public class AdapterMessage extends RecyclerView.Adapter<AdapterMessage.ViewHold
     private static boolean debug;
 
     private boolean gotoTop = false;
+    private Integer gotoPos = null;
     private boolean firstClick = false;
     private int searchResult = 0;
     private AsyncPagedListDiffer<TupleMessageEx> differ;
@@ -5441,6 +5442,11 @@ public class AdapterMessage extends RecyclerView.Adapter<AdapterMessage.ViewHold
                     }
                 }
 
+                if (gotoPos != null && currentList != null && currentList.size() > 0) {
+                    properties.scrollTo(gotoPos, 0);
+                    gotoPos = null;
+                }
+
                 if (selectionTracker != null && selectionTracker.hasSelection()) {
                     Selection<Long> selection = selectionTracker.getSelection();
 
@@ -5530,6 +5536,11 @@ public class AdapterMessage extends RecyclerView.Adapter<AdapterMessage.ViewHold
         this.gotoTop = true;
     }
 
+    void gotoPos(int pos) {
+        if (pos != RecyclerView.NO_POSITION)
+            gotoPos = pos;
+    }
+
     void submitList(PagedList<TupleMessageEx> list) {
         for (int i = 0; i < list.size(); i++) {
             TupleMessageEx message = list.get(i);

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

@@ -300,6 +300,7 @@ public class FragmentMessages extends FragmentBase implements SharedPreferences.
     private SelectionPredicateMessage selectionPredicate = null;
     private SelectionTracker<Long> selectionTracker = null;
 
+    private Integer scroll = null;
     private Long prev = null;
     private Long next = null;
     private Long closeId = null;
@@ -3373,6 +3374,9 @@ public class FragmentMessages extends FragmentBase implements SharedPreferences.
         if (rvMessage != null) {
             Parcelable rv = rvMessage.getLayoutManager().onSaveInstanceState();
             outState.putParcelable("fair:rv", rv);
+
+            LinearLayoutManager llm = (LinearLayoutManager) rvMessage.getLayoutManager();
+            outState.putInt("fair:scroll", llm.findFirstVisibleItemPosition());
         }
 
         if (selectionTracker != null)
@@ -3402,6 +3406,8 @@ public class FragmentMessages extends FragmentBase implements SharedPreferences.
                 rvMessage.getLayoutManager().onRestoreInstanceState(rv);
             }
 
+            adapter.gotoPos(savedInstanceState.getInt("fair:scroll"));
+
             if (selectionTracker != null)
                 selectionTracker.onRestoreInstanceState(savedInstanceState);
         }