Disable multiple select on swiping

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

@@ -134,6 +134,7 @@ public class FragmentMessages extends FragmentBase {
     private AdapterMessage adapter;
 
     private AdapterMessage.ViewType viewType;
+    private SelectionPredicateMessage selectionPredicate = null;
     private SelectionTracker<Long> selectionTracker = null;
 
     private Long previous = null;
@@ -424,7 +425,7 @@ public class FragmentMessages extends FragmentBase {
             });
 
         } else {
-            final SelectionPredicateMessage predicate = new SelectionPredicateMessage(rvMessage);
+            selectionPredicate = new SelectionPredicateMessage(rvMessage);
 
             selectionTracker = new SelectionTracker.Builder<>(
                     "messages-selection",
@@ -432,7 +433,7 @@ public class FragmentMessages extends FragmentBase {
                     new ItemKeyProviderMessage(rvMessage),
                     new ItemDetailsLookupMessage(rvMessage),
                     StorageStrategy.createLongStorage())
-                    .withSelectionPredicate(predicate)
+                    .withSelectionPredicate(selectionPredicate)
                     .build();
             adapter.setSelectionTracker(selectionTracker);
 
@@ -690,6 +691,9 @@ public class FragmentMessages extends FragmentBase {
             AdapterMessage.ViewHolder holder = ((AdapterMessage.ViewHolder) viewHolder);
             holder.setDisplacement(dX);
 
+            if (selectionPredicate != null)
+                selectionPredicate.setEnabled(!isCurrentlyActive);
+
             TupleMessageEx message = getMessage(viewHolder);
             if (message == null)
                 return;

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

@@ -24,14 +24,23 @@ import androidx.recyclerview.selection.SelectionTracker;
 import androidx.recyclerview.widget.RecyclerView;
 
 public class SelectionPredicateMessage extends SelectionTracker.SelectionPredicate<Long> {
+    private boolean enabled;
     private RecyclerView recyclerView;
 
     SelectionPredicateMessage(RecyclerView recyclerView) {
+        this.enabled = true;
         this.recyclerView = recyclerView;
     }
 
+    void setEnabled(boolean enabled) {
+        this.enabled = enabled;
+    }
+
     @Override
     public boolean canSetStateForKey(@NonNull Long key, boolean nextState) {
+        if (!enabled)
+            return false;
+
         AdapterMessage adapter = (AdapterMessage) recyclerView.getAdapter();
         TupleMessageEx message = adapter.getItemForKey(key);
 
@@ -43,6 +52,9 @@ public class SelectionPredicateMessage extends SelectionTracker.SelectionPredica
 
     @Override
     public boolean canSetStateAtPosition(int position, boolean nextState) {
+        if (!enabled)
+            return false;
+
         AdapterMessage adapter = (AdapterMessage) recyclerView.getAdapter();
         TupleMessageEx message = adapter.getItemAtPosition(position);