Make the transitions more solid by having an open/close set of functions to maintain cleaning up internal state.

gui/dnd_loot.cpp

@@ -31,7 +31,7 @@ namespace gui {
 
   void DNDLoot::START(Event ev) {
     dbc::check(ev == Event::STARTED, "START not given a STARTED event.");
-    state(DNDState::END);
+    END(Event::CLOSE);
   }
 
   void DNDLoot::LOOTING(Event ev, std::any data) {
@@ -39,8 +39,7 @@ namespace gui {
 
     switch(ev) {
       case LOOT_OPEN:
-        $loot_ui.active = false;
-        state(DNDState::END);
+        END(Event::CLOSE);
         break;
       case LOOT_SELECT:
         $grab_source = UISystem::loot_grab($loot_ui.$gui, data);
@@ -64,8 +63,7 @@ namespace gui {
 
     switch(ev) {
       case LOOT_OPEN:
-        $loot_ui.active = false;
-        state(DNDState::END);
+        END(Event::CLOSE);
         break;
       case LOOT_SELECT:
         $grab_source = UISystem::loot_grab($loot_ui.$gui, data);
@@ -88,8 +86,7 @@ namespace gui {
 
     switch(ev) {
       case LOOT_OPEN:
-        $loot_ui.active = false;
-        state(DNDState::END);
+        END(Event::CLOSE);
         break;
       case LOOT_SELECT:
         if(UISystem::loot_drop($status_ui.$gui,
@@ -115,9 +112,7 @@ namespace gui {
         if(UISystem::loot_drop($loot_ui.$gui,
               $status_ui.$gui, $grab_source, data))
         {
-          $grab_source = std::nullopt;
-          $grab_sprite = nullptr;
-          state(DNDState::END);
+          END(Event::CLOSE);
         }
         break;
       case LOOT_ITEM:
@@ -146,11 +141,14 @@ namespace gui {
           }
         } break;
       case LOOT_OPEN:
-        $loot_ui.active = true;
-        $grab_source = std::nullopt;
-        $grab_sprite = nullptr;
+        open();
         state(DNDState::LOOTING);
         break;
+      case CLOSE:
+        // called the first time transitioning to END
+        close();
+        state(DNDState::END);
+        break;
       default:
         dbc::sentinel(fmt::format("invalid event: {}", int(ev)));
     }
@@ -193,6 +191,18 @@ namespace gui {
     }
   }
 
+  void DNDLoot::open() {
+    $grab_source = std::nullopt;
+    $grab_sprite = nullptr;
+    $loot_ui.active = true;
+  }
+
+  void DNDLoot::close() {
+    $grab_source = std::nullopt;
+    $grab_sprite = nullptr;
+    $loot_ui.active = false;
+  }
+
   void DNDLoot::render() {
     if($grab_source && $grab_sprite) {
       $window.draw(*$grab_sprite);

gui/dnd_loot.hpp

@@ -39,6 +39,8 @@ namespace gui {
       void handle_mouse(Event ev, guecs::UI& gui);
       void mouse_action(bool hover);
       void render();
+      void open();
+      void close();
       sf::Vector2f mouse_position();
   };
 }