Worked out an initial stab at a GrabSource for drag-n-drop or just simple grabbing things in the UI.

gui/fsm.cpp

@@ -10,6 +10,7 @@
 #include "sound.hpp"
 #include "shaders.hpp"
 #include <fmt/xchar.h>
+#include "gui/guecstra.hpp"
 
 namespace gui {
   using namespace components;
@@ -57,7 +58,6 @@ namespace gui {
   }
 
   void FSM::START(Event ) {
-
     $main_ui.update_level($level);
     $main_ui.init();
     $loot_ui.init();
@@ -133,37 +133,34 @@ namespace gui {
         break;
       case LOOT_SELECT: {
           int slot_id = std::any_cast<int>(data);
-          if(auto entity = $loot_ui.select_slot(slot_id)) {
-            $status_ui.select_slot(slot_id, *entity);
-            $dumb_sprite = $loot_ui.grab_sprite(slot_id);
-
-            $window.setMouseCursorVisible(false);
-            $dumb_sprite->setOrigin({128, 128});
-            $dumb_sprite->setPosition({
-                float($router.position.x),
-                float($router.position.y)
-            });
+
+          if(auto world_entity = $loot_ui.select_slot(slot_id)) {
+            $grab_source = $loot_ui.$gui.entity("item_", slot_id);
+            auto& source = $loot_ui.get_grabber(*$grab_source);
+
+            source.grab($window);
+            source.move($router.position);
+
+            $status_ui.select_slot(slot_id, *world_entity);
           }
         } break;
       case INV_SELECT: {
           std::string slot_name = std::any_cast<std::string>(data);
           int slot_id = $status_ui.place_slot(slot_name);
+          dbc::check(slot_id != -1, "status_ui is trying to place -1 slot_id");
           if(slot_id != -1) {
             $loot_ui.remove_slot(slot_id);
           }
           $window.setMouseCursorVisible(true);
-          $dumb_sprite = nullptr;
           state(State::LOOTING);
         } break;
       case MOUSE_CLICK:
         mouse_action(false);
         break;
       case MOUSE_MOVE: {
-        if($dumb_sprite) {
-          $dumb_sprite->setPosition({
-              float($router.position.x),
-              float($router.position.y)
-          });
+        if($grab_source) {
+          auto& source = $loot_ui.get_grabber(*$grab_source);
+          source.move($router.position);
         }
         mouse_action(true);
        } break;
@@ -171,11 +168,9 @@ namespace gui {
           mouse_action(false);
        } break;
       case MOUSE_DRAG: {
-        if($dumb_sprite) {
-          $dumb_sprite->setPosition({
-              float($router.position.x),
-              float($router.position.y)
-          });
+        if($grab_source) {
+          auto& source = $loot_ui.get_grabber(*$grab_source);
+          source.move($router.position);
         }
         mouse_action(true);
        } break;
@@ -241,6 +236,7 @@ namespace gui {
         state(State::INV_GRAB);
         INV_GRAB(ev, data);
         break;
+      case MOUSE_DRAG_START:
       case MOUSE_CLICK:
         mouse_action(false);
         break;

gui/fsm.hpp

@@ -49,7 +49,8 @@ namespace gui {
       LootUI $loot_ui;
       sf::Font $font;
       gui::routing::Router $router;
-      shared_ptr<sf::Sprite> $dumb_sprite = nullptr;
+      std::optional<DinkyECS::Entity> $grab_source;
+      std::optional<DinkyECS::Entity> $drop_target;
 
       FSM();
 

gui/guecstra.hpp

@@ -1,8 +1,28 @@
+#pragma once
 #include "components.hpp"
 #include "events.hpp"
 #include <guecs/ui.hpp>
+#include "textures.hpp"
 
 namespace guecs {
   Clickable make_action(DinkyECS::World& target, Events::GUI event);
   Clickable make_action(DinkyECS::World& target, Events::GUI event, std::any data);
+
+  struct GrabSource : public Sprite {
+    void grab(sf::RenderWindow& window) {
+      window.setMouseCursorVisible(false);
+      sprite->setOrigin({128, 128});
+    }
+
+    void move(sf::Vector2i position) {
+      sprite->setPosition({
+          float(position.x),
+          float(position.y)
+      });
+    }
+  };
+
+  struct DropTarget {
+
+  };
 }

gui/loot_ui.cpp

@@ -1,7 +1,6 @@
 #include "gui/loot_ui.hpp"
 #include "constants.hpp"
 #include <fmt/xchar.h>
-#include "gui/guecstra.hpp"
 
 namespace gui {
   using namespace guecs;
@@ -55,12 +54,6 @@ namespace gui {
     }
   }
 
-  shared_ptr<sf::Sprite> LootUI::grab_sprite(int slot_id) {
-    auto id = $gui.entity("item_", slot_id);
-    auto& sprite = $gui.get<guecs::Sprite>(id);
-    return sprite.sprite;
-  }
-
   void LootUI::remove_slot(int slot_id) {
     dbc::check(size_t(slot_id) < contents.size(),
         fmt::format("invalid slot id {} give, contents.size={}",
@@ -83,12 +76,16 @@ namespace gui {
       if(i < contents.size()) {
         auto item = contents.at(i);
         auto& sprite = $level.world->get<components::Sprite>(item);
-        fmt::println("NEW SPRITE SPRITE {}", sprite.name);
-        $gui.set_init<guecs::Sprite>(id, {sprite.name});
+        guecs::GrabSource grabber{sprite.name};
+        $gui.set_init<guecs::Sprite>(id, grabber);
       }
     }
   }
 
+  guecs::GrabSource& LootUI::get_grabber(DinkyECS::Entity entity) {
+    return static_cast<guecs::GrabSource&>($gui.get<guecs::Sprite>(entity));
+  }
+
   void LootUI::render(sf::RenderWindow& window) {
     $gui.render(window);
   }

gui/loot_ui.hpp

@@ -1,4 +1,5 @@
 #pragma once
+#include "gui/guecstra.hpp"
 #include "levelmanager.hpp"
 #include <SFML/Graphics/RenderWindow.hpp>
 #include <SFML/Graphics/Font.hpp>
@@ -22,6 +23,6 @@ namespace gui {
       bool mouse(float x, float y, bool hover);
       std::optional<DinkyECS::Entity> select_slot(int slot);
       void remove_slot(int slot_id);
-      shared_ptr<sf::Sprite> grab_sprite(int slot_id);
+      guecs::GrabSource& get_grabber(DinkyECS::Entity entity);
   };
 }