Fix major incorrect usage of mrb class definitions causing segfaults

Makefile

@@ -24,7 +24,7 @@ CFLAGS_DEBUG := \
 	-std=c++20 -Wall -Wextra \
 	-O0 -g -fno-omit-frame-pointer \
 	-Wno-unused-command-line-argument \
-	-I./include \
+	-I./include -I./libs/mruby/include \
 	$(SDL_CFLAGS)
 
 CFLAGS_RELEASE := \
@@ -32,7 +32,7 @@ CFLAGS_RELEASE := \
 	-flto=thin \
 	-fno-rtti -fomit-frame-pointer -DNDEBUG -s \
 	-Wno-unused-command-line-argument \
-	-I./include \
+	-I./include -I./libs/mruby/include \
 	$(SDL_CFLAGS)
 
 PCH_CFLAGS_DEBUG := $(CFLAGS_DEBUG) -x c++-header

include/app/app.h

@@ -8,7 +8,6 @@
 
 namespace app {
 struct Element {
-  int reference_count = 0;
   Vec2<float> position = {0, 0};
   float rotation = 0;
   Vec2<float> scale = {1, 1};
@@ -21,11 +20,8 @@ struct Element {
   virtual Vec2<float> size(Window *window) = 0;
 
   void click() {
-    if (!mrb_nil_p(on_click.proc)) {
-      int x = mrb_gc_arena_save(Ruby::mrb);
+    if (!mrb_nil_p(on_click.proc))
       on_click.call();
-      mrb_gc_arena_restore(Ruby::mrb, x);
-    }
   }
 };
 
@@ -93,22 +89,16 @@ struct ERect : Element {
   }
 };
 
-inline Pool<Element *> element_pool;
+inline Pool<Element> element_pool;
 
 struct Scene {
-  bool unused = false;
   std::vector<int> element_ids;
   Ruby::Block update;
 
   ~Scene() {
-    for (const int &id : element_ids) {
-      element_pool[id]->reference_count--;
-      if (element_pool[id]->reference_count <= 0) {
-        delete element_pool[id];
+    for (const int &id : element_ids)
       element_pool.release(id);
   }
-    }
-  }
 
   void add_element(int element_id) {
     auto it = std::lower_bound(
@@ -116,31 +106,27 @@ struct Scene {
       element_ids.end(),
       element_id,
       [](auto &a, auto &b) {
-        return element_pool[a]->z < element_pool[b]->z || (element_pool[a]->z == element_pool[b]->z && a < b);
+        auto e_a = element_pool[a];
+        auto e_b = element_pool[b];
+        return e_a->z < e_b->z || (e_a->z == e_b->z && a < b);
       }
     );
-    element_pool[element_id]->reference_count++;
+    element_pool.use(element_id);
     element_ids.insert(it, element_id);
   }
 
   void delete_element(int element_id) {
     auto it = std::find(element_ids.begin(), element_ids.end(), element_id);
     if (it != element_ids.end()) {
-      element_pool[element_id]->reference_count--;
-      if (element_pool[element_id]->reference_count <= 0) {
-        delete element_pool[element_id];
       element_pool.release(element_id);
-      }
       element_ids.erase(it);
     }
   }
 
   void update_scene(uint64_t delta_time) {
     if (!mrb_nil_p(update.proc)) {
-      int x = mrb_gc_arena_save(Ruby::mrb);
       mrb_value dt_val = mrb_int_value(Ruby::mrb, delta_time);
       update.call(1, &dt_val);
-      mrb_gc_arena_restore(Ruby::mrb, x);
     }
   }
 
@@ -165,24 +151,15 @@ struct Scene {
   }
 };
 
-inline Pool<Scene *> scene_pool;
+inline Pool<Scene> scene_pool;
 
 struct App {
   int current_scene_id = 0;
   bool running = true;
 
   void switch_to_scene(int scene_id) {
-    int scene_pool_size = (int)scene_pool.all().size();
-    for (int i = 0; i < scene_pool_size; ++i) {
-      auto &val = scene_pool[i];
-      if (i == scene_id && val != nullptr && val->unused)
-        val->unused = false;
-      if (val != nullptr && val->unused) {
-        delete val;
-        scene_pool.release(i);
-      }
-    }
-
+    scene_pool.release(current_scene_id);
+    scene_pool.use(scene_id);
     current_scene_id = scene_id;
   }
 

include/binding/definitions.h

@@ -27,17 +27,63 @@ DEF_RB(
   })
 )
 
+DEF_RB(
+  Image,
+  ({ window.unload_image(id); }),
+  ({
+    char *path;
+    mrb_value kwargs;
+    mrb_get_args(mrb, "z|H", &path, &kwargs);
+
+    float alpha = 1.0f;
+    bool pixel_art = false;
+    if (!mrb_nil_p(kwargs)) {
+      HASH_FLOAT(kwargs, alpha, alpha);
+      HASH_BOOL(kwargs, pixel_art, pixel_art);
+    }
+
+    s->id = window.load_image(path, alpha, pixel_art);
+#warning "Fix lifetimes for images/fonts right now they'll always exist"
+  })
+)
+
+DEF_RB(
+  Animation,
+  ({
+    animation_pool.release(id);
+  }),
+  ({
+    const mrb_value *frames_val;
+    mrb_int frames_len;
+    mrb_value kwargs;
+    mrb_get_args(mrb, "a|H", &frames_val, &frames_len, &kwargs);
+
+    float fps = 1.0f;
+    if (!mrb_nil_p(kwargs))
+      HASH_FLOAT(kwargs, fps, fps);
+
+    std::vector<int> frame_ids;
+    for (mrb_int i = 0; i < frames_len; i++) {
+      mrb_value frame_val = frames_val[i];
+      if (!mrb_obj_is_kind_of(mrb, frame_val, mrb_class_get(mrb, "Image"))) {
+        mrb_raise(mrb, mrb_class_get(mrb, "Exception"), "Expected an array of Image objects");
+        return mrb_nil_value();
+      }
+      int frame_id = get_id_Image(mrb, frame_val);
+      window.use_image(frame_id);
+      frame_ids.push_back(frame_id);
+    }
+
+    Animation *animation = new Animation{frame_ids, fps, true};
+    s->id = animation_pool.acquire(animation);
+    animation_pool.use(s->id);
+  })
+)
+
 DEF_RB(
   ElementText,
   ({
-    app::Element *element = app::element_pool[id];
-    if (element != nullptr)
-      element->reference_count--;
-
-    if (element != nullptr && element->reference_count <= 0) {
-      delete element;
     app::element_pool.release(id);
-    }
   }),
   ({
     mrb_value font_val;
@@ -48,7 +94,7 @@ DEF_RB(
     auto key_id = Localization::key_from_sym(mrb, key);
 
     if (!mrb_obj_is_kind_of(mrb, font_val, mrb_class_get(mrb, "Font"))) {
-      mrb_raise(mrb, mrb_class_get(Ruby::mrb, "Exception"), "Expected a Font object");
+      mrb_raise(mrb, mrb_class_get(mrb, "Exception"), "Expected a Font object");
       return mrb_nil_value();
     }
 
@@ -67,29 +113,32 @@ DEF_RB(
 
     Vec2<float> position = {x, y};
 
-    int id = get_id(font_val);
+    int id = get_id_Font(mrb, font_val);
+    window.use_font(id);
 
     app::EText *element = new app::EText(key_id, id, {255, 255, 255, 255});
-    element->reference_count++;
     element->position = position;
     element->z = z;
     element->click_through = click_through;
 
     s->id = app::element_pool.acquire(element);
+    app::element_pool.use(s->id);
   })
 )
 
+static mrb_value element_text_on_click(mrb_state *mrb, mrb_value self) {
+  mrb_value block;
+  mrb_get_args(mrb, "&", &block);
+  int id = get_id_ElementText(mrb, self);
+  app::Element *element = app::element_pool[id];
+  element->on_click.set_proc(block);
+  return self;
+}
+
 DEF_RB(
   ElementRect,
   ({
-    app::Element *element = app::element_pool[id];
-    if (element != nullptr)
-      element->reference_count--;
-
-    if (element != nullptr && element->reference_count <= 0) {
-      delete element;
     app::element_pool.release(id);
-    }
   }),
   ({
     mrb_value shape_val;
@@ -119,18 +168,27 @@ DEF_RB(
        (uint8_t)((color >> 8) & 0xFF),
        (uint8_t)(color & 0xFF)}
     );
-    element->reference_count++;
     element->position = position;
     element->z = z;
 
     s->id = app::element_pool.acquire(element);
+    app::element_pool.use(s->id);
   })
 )
 
+static mrb_value element_rect_on_click(mrb_state *mrb, mrb_value self) {
+  mrb_value block;
+  mrb_get_args(mrb, "&", &block);
+  int id = get_id_ElementRect(mrb, self);
+  app::Element *element = app::element_pool[id];
+  element->on_click.set_proc(block);
+  return self;
+}
+
 static mrb_value element_rect_color_set(mrb_state *mrb, mrb_value self) {
   mrb_value color_val;
   mrb_get_args(mrb, "o", &color_val);
-  int id = get_id(self);
+  int id = get_id_ElementRect(mrb, self);
   app::ERect *element = (app::ERect *)app::element_pool[id];
   element->color = {
     (uint8_t)((mrb_fixnum(color_val) >> 24) & 0xFF),
@@ -141,17 +199,8 @@ static mrb_value element_rect_color_set(mrb_state *mrb, mrb_value self) {
   return self;
 }
 
-static mrb_value element_on_click(mrb_state *mrb, mrb_value self) {
-  mrb_value block;
-  mrb_get_args(mrb, "&", &block);
-  int id = get_id(self);
-  app::Element *element = app::element_pool[id];
-  element->on_click.set_proc(block);
-  return self;
-}
-
-static mrb_value element_rect_color_get(mrb_state *, mrb_value self) {
-  int id = get_id(self);
+static mrb_value element_rect_color_get(mrb_state *mrb, mrb_value self) {
+  int id = get_id_ElementRect(mrb, self);
   app::ERect *element = (app::ERect *)app::element_pool[id];
   uint32_t color = ((uint32_t)element->color.r << 24)
                    | ((uint32_t)element->color.g << 16)
@@ -160,16 +209,65 @@ static mrb_value element_rect_color_get(mrb_state *, mrb_value self) {
   return mrb_fixnum_value(color);
 }
 
+DEF_RB(
+  ElementImage,
+  ({
+    app::element_pool.release(id);
+  }),
+  ({
+    mrb_value animation_val;
+    mrb_value kwargs;
+    mrb_get_args(mrb, "o|H", &animation_val, &kwargs);
+
+    if (!mrb_obj_is_kind_of(mrb, animation_val, mrb_class_get(mrb, "Animation"))) {
+      mrb_raise(mrb, mrb_class_get(mrb, "Exception"), "Expected an Animation object");
+      return mrb_nil_value();
+    }
+
+    float x = 0;
+    float y = 0;
+    float z = 0;
+    bool click_through = false;
+    if (!mrb_nil_p(kwargs)) {
+      mrb_value pos_hash = HASH_GET(kwargs, position);
+      HASH_FLOAT(pos_hash, x, x);
+      HASH_FLOAT(pos_hash, y, y);
+
+      HASH_FLOAT(kwargs, z, z);
+      HASH_BOOL(kwargs, click_through, click_through);
+    }
+
+    int id = get_id_Animation(mrb, animation_val);
+    Animation *animation = animation_pool[id];
+
+    app::EImage *element = new app::EImage(*animation);
+    element->position = {x, y};
+    element->z = z;
+    element->click_through = click_through;
+
+    s->id = app::element_pool.acquire(element);
+    app::element_pool.use(s->id);
+  })
+)
+
+static mrb_value element_image_on_click(mrb_state *mrb, mrb_value self) {
+  mrb_value block;
+  mrb_get_args(mrb, "&", &block);
+  int id = get_id_ElementImage(mrb, self);
+  app::Element *element = app::element_pool[id];
+  element->on_click.set_proc(block);
+  return self;
+}
+
 DEF_RB(
   Scene,
   ({
-    app::Scene *scene = app::scene_pool[id];
-    if (scene != nullptr)
-      scene->unused = true;
+    app::scene_pool.release(id);
   }),
   ({
     app::Scene *loading_scene = new app::Scene{};
     s->id = app::scene_pool.acquire(loading_scene);
+    app::scene_pool.use(s->id);
   })
 )
 
@@ -180,23 +278,75 @@ static mrb_value scene_add_element(mrb_state *mrb, mrb_value self) {
   if (
     !mrb_obj_is_kind_of(mrb, element_val, mrb_class_get(mrb, "ElementText"))
     && !mrb_obj_is_kind_of(mrb, element_val, mrb_class_get(mrb, "ElementRect"))
+    && !mrb_obj_is_kind_of(mrb, element_val, mrb_class_get(mrb, "ElementImage"))
   ) {
-    mrb_raise(mrb, mrb_class_get(Ruby::mrb, "Exception"), "Expected an ElementText or ElementRect object");
+    mrb_raise(mrb, mrb_class_get(mrb, "Exception"), "Expected an ElementText, ElementRect, or ElementImage object");
     return mrb_nil_value();
   }
 
-  int id = get_id(self);
+  int id = get_id_Scene(mrb, self);
+  app::Scene *scene = app::scene_pool[id];
+
+  // int element_id = get_id_Element(mrb, element_val);
+
+  int element_id;
+  if (mrb_obj_is_kind_of(mrb, element_val, mrb_class_get(mrb, "ElementText"))) {
+    element_id = get_id_ElementText(mrb, element_val);
+  } else if (mrb_obj_is_kind_of(mrb, element_val, mrb_class_get(mrb, "ElementRect"))) {
+    element_id = get_id_ElementRect(mrb, element_val);
+  } else if (mrb_obj_is_kind_of(mrb, element_val, mrb_class_get(mrb, "ElementImage"))) {
+    element_id = get_id_ElementImage(mrb, element_val);
+  } else {
+    mrb_raise(mrb, mrb_class_get(mrb, "Exception"), "Expected an ElementText, ElementRect, or ElementImage object");
+    return mrb_nil_value();
+  }
+
+  scene->add_element(element_id);
+
+  return self;
+}
+
+static mrb_value scene_delete_element(mrb_state *mrb, mrb_value self) {
+  mrb_value element_val;
+  mrb_get_args(mrb, "o", &element_val);
+
+  if (
+    !mrb_obj_is_kind_of(mrb, element_val, mrb_class_get(mrb, "ElementText"))
+    && !mrb_obj_is_kind_of(mrb, element_val, mrb_class_get(mrb, "ElementRect"))
+    && !mrb_obj_is_kind_of(mrb, element_val, mrb_class_get(mrb, "ElementImage"))
+  ) {
+    mrb_raise(mrb, mrb_class_get(mrb, "Exception"), "Expected an ElementText, ElementRect, or ElementImage object");
+    return mrb_nil_value();
+  }
+
+  int id = get_id_Scene(mrb, self);
   app::Scene *scene = app::scene_pool[id];
 
   int element_id;
-  if (
-    mrb_obj_is_kind_of(mrb, element_val, mrb_class_get(mrb, "ElementText"))
-    || mrb_obj_is_kind_of(mrb, element_val, mrb_class_get(mrb, "ElementRect"))
-  ) {
-    element_id = get_id(element_val);
-    scene->add_element(element_id);
+  if (mrb_obj_is_kind_of(mrb, element_val, mrb_class_get(mrb, "ElementText"))) {
+    element_id = get_id_ElementText(mrb, element_val);
+  } else if (mrb_obj_is_kind_of(mrb, element_val, mrb_class_get(mrb, "ElementRect"))) {
+    element_id = get_id_ElementRect(mrb, element_val);
+  } else if (mrb_obj_is_kind_of(mrb, element_val, mrb_class_get(mrb, "ElementImage"))) {
+    element_id = get_id_ElementImage(mrb, element_val);
+  } else {
+    mrb_raise(mrb, mrb_class_get(mrb, "Exception"), "Expected an ElementText, ElementRect, or ElementImage object");
+    return mrb_nil_value();
   }
 
+  scene->delete_element(element_id);
+
+  return self;
+}
+
+static mrb_value scene_on_update(mrb_state *mrb, mrb_value self) {
+  mrb_value block;
+  mrb_get_args(mrb, "&", &block);
+
+  int id = get_id_Scene(mrb, self);
+  app::Scene *scene = app::scene_pool[id];
+  scene->update.set_proc(block);
+
   return self;
 }
 
@@ -223,12 +373,13 @@ static mrb_value app_start(mrb_state *mrb, mrb_value) {
   mrb_get_args(mrb, "o", &scene_val);
 
   if (!mrb_obj_is_kind_of(mrb, scene_val, mrb_class_get(mrb, "Scene"))) {
-    mrb_raise(mrb, mrb_class_get(Ruby::mrb, "Exception"), "Expected a Scene object");
+    mrb_raise(mrb, mrb_class_get(mrb, "Exception"), "Expected a Scene object");
     return mrb_nil_value();
   }
 
-  int id = get_id(scene_val);
+  int id = get_id_Scene(mrb, scene_val);
   app_->switch_to_scene(id);
+
   app_->loop();
 
   return mrb_nil_value();
@@ -239,11 +390,11 @@ static mrb_value app_switch_to(mrb_state *mrb, mrb_value) {
   mrb_get_args(mrb, "o", &scene_val);
 
   if (!mrb_obj_is_kind_of(mrb, scene_val, mrb_class_get(mrb, "Scene"))) {
-    mrb_raise(mrb, mrb_class_get(Ruby::mrb, "Exception"), "Expected a Scene object");
+    mrb_raise(mrb, mrb_class_get(mrb, "Exception"), "Expected a Scene object");
     return mrb_nil_value();
   }
 
-  int id = get_id(scene_val);
+  int id = get_id_Scene(mrb, scene_val);
   app_->switch_to_scene(id);
 
   return mrb_nil_value();
@@ -284,11 +435,15 @@ static mrb_value app_language_set(mrb_state *mrb, mrb_value) {
 inline void setup() {
   DEF_CLASS(Font, MRB_ARGS_REQ(2) | MRB_ARGS_OPT(1));
 
+  DEF_CLASS(Image, MRB_ARGS_REQ(1) | MRB_ARGS_OPT(1));
+
+  DEF_CLASS(Animation, MRB_ARGS_REQ(1) | MRB_ARGS_OPT(1));
+
   DEF_CLASS(ElementText, MRB_ARGS_REQ(2) | MRB_ARGS_OPT(1));
   ADD_METHOD(
     ElementText,
     "on_click",
-    element_on_click,
+    element_text_on_click,
     MRB_ARGS_BLOCK()
   );
 
@@ -296,7 +451,7 @@ inline void setup() {
   ADD_METHOD(
     ElementRect,
     "on_click",
-    element_on_click,
+    element_rect_on_click,
     MRB_ARGS_BLOCK()
   );
   ADD_METHOD(
@@ -312,8 +467,19 @@ inline void setup() {
     MRB_ARGS_NONE()
   );
 
+  DEF_CLASS(ElementImage, MRB_ARGS_REQ(1) | MRB_ARGS_OPT(1));
+  ADD_METHOD(
+    ElementImage,
+    "on_click",
+    element_image_on_click,
+    MRB_ARGS_BLOCK()
+  );
+
   DEF_CLASS(Scene, MRB_ARGS_NONE());
   ADD_METHOD(Scene, "<<", scene_add_element, MRB_ARGS_REQ(1));
+  ADD_METHOD(Scene, "delete", scene_delete_element, MRB_ARGS_REQ(1));
+  ADD_METHOD(Scene, "remove", scene_delete_element, MRB_ARGS_REQ(1));
+  ADD_METHOD(Scene, "on_update", scene_on_update, MRB_ARGS_BLOCK());
 
   DEF_MODULE(App);
   ADD_MODULE_METHOD(App, "run", app_run, MRB_ARGS_REQ(3));

include/binding/ruby.h

@@ -12,8 +12,12 @@
 #define HASH_FLOAT(h, key, out)     \
   do {                              \
     mrb_value v = HASH_GET(h, key); \
-    if (mrb_fixnum_p(v))            \
+    if (mrb_float_p(v))             \
+      out = mrb_float(v);           \
+    else if (mrb_fixnum_p(v))       \
       out = (float)mrb_fixnum(v);   \
+    else                            \
+      out = 0;                      \
   } while (0)
 
 #define HASH_BOOL(h, key, out)      \
@@ -40,11 +44,19 @@ struct Wrapper {
   };                                                             \
   static mrb_value NAME##_init(mrb_state *mrb, mrb_value self) { \
     UNUSED(mrb);                                                 \
+    Wrapper *old = (Wrapper *)DATA_PTR(self);                    \
+    if (old)                                                     \
+      mrb_free(mrb, old);                                        \
+    mrb_data_init(self, nullptr, &NAME##_type);                  \
     Wrapper *s = new Wrapper();                                  \
     FN_INIT;                                                     \
-    DATA_PTR(self) = s;                                          \
-    DATA_TYPE(self) = &NAME##_type;                              \
+    mrb_data_init(self, s, &NAME##_type);                        \
     return self;                                                 \
+  }                                                              \
+  inline int get_id_##NAME(mrb_state *mrb, mrb_value self) {     \
+    Wrapper *wrapper;                                            \
+    Data_Get_Struct(mrb, self, &NAME##_type, wrapper);           \
+    return wrapper->id;                                          \
   }
 
 #define ADD_METHOD(NAME, METHOD, FUNC, ARGS) \
@@ -52,6 +64,7 @@ struct Wrapper {
 
 #define DEF_CLASS(NAME, ARGS)                                                         \
   RClass *NAME##_class = mrb_define_class(Ruby::mrb, #NAME, Ruby::mrb->object_class); \
+  MRB_SET_INSTANCE_TT(NAME##_class, MRB_TT_CDATA);                                    \
   ADD_METHOD(NAME, "initialize", NAME##_init, ARGS);
 
 #define DEF_MODULE(NAME) \
@@ -60,10 +73,6 @@ struct Wrapper {
 #define ADD_MODULE_METHOD(MODULE, METHOD, FUNC, ARGS) \
   mrb_define_class_method(Ruby::mrb, MODULE##_module, METHOD, FUNC, ARGS);
 
-inline int get_id(mrb_value self) {
-  return ((Wrapper *)DATA_PTR(self))->id;
-}
-
 namespace Ruby {
 inline mrb_state *mrb = mrb_open();
 
@@ -71,7 +80,7 @@ struct Block {
   mrb_value proc;
 
   Block(mrb_value proc) : proc(proc) {
-    mrb_gc_register(mrb, proc);
+    mrb_gc_protect(mrb, proc);
   }
 
   Block() : proc(mrb_nil_value()) {}
@@ -81,7 +90,7 @@ struct Block {
       mrb_gc_unregister(mrb, proc);
     proc = new_proc;
     if (!mrb_nil_p(proc))
-      mrb_gc_register(mrb, proc);
+      mrb_gc_protect(mrb, proc);
   }
 
   Block(const Block &) = delete;
@@ -90,7 +99,8 @@ struct Block {
   mrb_value call(int argc = 0, mrb_value *argv = nullptr) const {
     if (mrb_nil_p(proc))
       return mrb_nil_value();
-    return mrb_funcall(mrb, proc, "call", argc, argv);
+    mrb_value result = mrb_funcall_argv(mrb, proc, mrb_intern_cstr(mrb, "call"), argc, argv);
+    return result;
   }
 
   ~Block() {
@@ -110,7 +120,10 @@ DEF_SYM(bold)
 DEF_SYM(italic)
 DEF_SYM(underline)
 DEF_SYM(position)
+DEF_SYM(alpha)
+DEF_SYM(fps)
 DEF_SYM(click_through)
+DEF_SYM(call)
 DEF_SYM(x)
 DEF_SYM(y)
 DEF_SYM(w)

include/pch.h

@@ -3,13 +3,29 @@
 
 #include "mruby.h"
 #include "mruby/array.h"
+#include "mruby/boxing_word.h"
+#include "mruby/class.h"
+#include "mruby/common.h"
 #include "mruby/compile.h"
 #include "mruby/data.h"
+#include "mruby/dump.h"
+#include "mruby/error.h"
+#include "mruby/gc.h"
 #include "mruby/hash.h"
+#include "mruby/internal.h"
 #include "mruby/irep.h"
+#include "mruby/numeric.h"
+#include "mruby/object.h"
+#include "mruby/opcode.h"
+#include "mruby/presym.h"
+#include "mruby/proc.h"
+#include "mruby/range.h"
+#include "mruby/re.h"
 #include "mruby/string.h"
+#include "mruby/throw.h"
 #include "mruby/value.h"
 #include "mruby/variable.h"
+#include "mruby/version.h"
 
 #include <SDL3/SDL.h>
 #include <SDL3/SDL_events.h>

include/utils.h

@@ -152,38 +152,71 @@ struct Rect {
   }
 };
 
-template <typename T>
+template <typename T = void *>
 struct Pool {
-  T &operator[](int index) {
-    return items[index];
+  T *operator[](int index) {
+    if (!is_valid(index)) {
+      fprintf(stderr, "Invalid pool index: %d\n", index);
+      return nullptr;
+    }
+    return slots[index].ptr;
   }
 
-  const std::vector<T> &all() {
-    return items;
+  const std::vector<T *> &all() {
+    static std::vector<T *> all_items;
+    all_items.clear();
+    for (const auto &slot : slots)
+      if (slot.alive)
+        all_items.push_back(slot.ptr);
+    return all_items;
   }
 
-  int acquire(const T &item) {
+  int acquire(T *item) {
+    int index;
     if (!free_indices.empty()) {
-      int index = free_indices.back();
+      index = free_indices.back();
       free_indices.pop_back();
-      items[index] = std::move(item);
-      return index;
     } else {
-      items.push_back(std::move(item));
-      return items.size() - 1;
+      index = slots.size();
+      slots.push_back({});
     }
+    slots[index].ptr = item;
+    slots[index].refcount = 1;
+    slots[index].alive = true;
+    return index;
+  }
+
+  void use(int index) {
+    if (is_valid(index))
+      slots[index].refcount++;
   }
 
   void release(int index) {
+    if (!is_valid(index))
+      return;
+    auto &slot = slots[index];
+    slot.refcount--;
+    if (slot.refcount <= 0) {
+      delete slot.ptr;
+      slot.ptr = nullptr;
+      slot.alive = false;
       free_indices.push_back(index);
     }
+  }
 
-  bool is_valid(size_t index) const {
-    return index >= 0 && index < items.size() && std::find(free_indices.begin(), free_indices.end(), index) == free_indices.end();
+  bool is_valid(int index) const {
+    return index >= 0
+           && index < (int)slots.size()
+           && slots[index].alive;
   }
 
 private:
-  std::vector<T> items;
+  struct Slot {
+    T *ptr = nullptr;
+    int refcount = 0;
+    bool alive = false;
+  };
+  std::vector<Slot> slots;
   std::vector<int> free_indices;
 };
 

include/window/window.h

@@ -14,6 +14,11 @@ struct Font {
   bool pixel_art;
 };
 
+struct Text {
+  SDL_Texture *texture;
+  Vec2<float> size;
+};
+
 struct Event {
   enum Type {
     NONE,
@@ -57,8 +62,11 @@ struct Animation {
   std::vector<int> frames;
   float frame_rate;
   bool loop;
+  int reference_count = 0;
 };
 
+inline Pool<Animation> animation_pool;
+
 struct Window {
 public:
   // title can be free'd by the caller after the window is created, as it's copied internally.
@@ -70,10 +78,12 @@ public:
 
   // Rendering functions
   int load_image(const char *path, float alpha = 1.0f, bool pixel_art = false);
+  void use_image(int image_id);
   void unload_image(int image_id);
   Vec2<float> get_image_size(int image_id);
 
   int load_font(const char *path, int font_size, bool bold = false, bool italic = false, bool underline = false, bool pixel_art = false);
+  void use_font(int font_id);
   void unload_font(int font_id);
 
   // text is copied internally, so it can be free'd by the caller after the text is created.
@@ -135,7 +145,7 @@ private:
   Pool<Font> font_pool;
 
   // Text pool
-  Pool<SDL_Texture *> text_pool;
+  Pool<Text> text_pool;
 
   struct RenderInstruction {
     enum Type {

samples/button.rb

@@ -1,8 +1,14 @@
-App.run 400, 400, "Button Test"
+App.run 720, 480, "Button Test"
 
 main_scene = Scene.new
+
 default_font = Font.new "assets/fonts/charybdis.ttf", 24, pixel_art: true
 
+bg_image1 = Image.new "assets/images/menu_bg.png", alpha: 0.7, pixel_art: true
+bg_image2 = Image.new "assets/images/game_over_dead_bg.png", alpha: 1, pixel_art: true
+
+bg_animation = Animation.new [bg_image1, bg_image2], fps: 5
+
 App.language = :en
 App.localize(:en, :btn_text, "Click me!")
 
@@ -10,6 +16,8 @@ text = ElementText.new :btn_text, default_font, position: {x: 50, y: 50}, z: 1,
 
 rect = ElementRect.new({x: 50, y: 50, w: 100, h: 25}, 0xFF0000FF, z: 0)
 
+image_element = ElementImage.new bg_animation, position: {x: 0, y: 0}, z: -1
+
 rect.on_click do
   rect.color = rect.color == 0xFF0000FF ?
     0x00FF00FF
@@ -17,14 +25,15 @@ rect.on_click do
     0xFF0000FF
 end
 
-=begin
-main_scene.update do |dt|
-  puts "Delta time: #{dt}ms"
+main_scene.on_update do |delta_time|
+  # puts "Delta time: #{delta_time}ms"
+  # commented out to avoid spamming the console, but you can uncomment to see the delta time being printed every frame
+  # runs at 60fps, so you should see around 16-17ms being printed
 end
-=end
 
 main_scene << text
 main_scene << rect
+main_scene << image_element
 
 # main_scene.delete(text) # Uncomment to test element deletion
 

src/window/window.cc

@@ -42,16 +42,13 @@ void Window::update(Vec2<float> new_size, const char *new_title) {
 
 Window::~Window() {
   for (auto &tex : image_pool.all())
-    if (tex.texture)
-      SDL_DestroyTexture(tex.texture);
+    SDL_DestroyTexture(tex->texture);
 
   for (auto tex : text_pool.all())
-    if (tex)
-      SDL_DestroyTexture(tex);
+    SDL_DestroyTexture(tex->texture);
 
   for (auto &f : font_pool.all())
-    if (f.font)
-      TTF_CloseFont(f.font);
+    TTF_CloseFont(f->font);
 
   SDL_DestroyRenderer(renderer);
   SDL_DestroyWindow(window);
@@ -76,7 +73,15 @@ int Window::load_image(const char *path, float alpha, bool pixel_art) {
   float w, h;
   SDL_GetTextureSize(texture, &w, &h);
 
-  return image_pool.acquire({texture, {w, h}});
+  Image *img = new Image{texture, {w, h}};
+  int id = image_pool.acquire(img);
+  image_pool.use(id);
+
+  return id;
+}
+
+void Window::use_image(int image_id) {
+  image_pool.use(image_id);
 }
 
 Vec2<float> Window::get_image_size(int image_id) {
@@ -84,7 +89,7 @@ Vec2<float> Window::get_image_size(int image_id) {
     fprintf(stderr, "Invalid image ID: %d\n", image_id);
     return {0, 0};
   }
-  return {image_pool[image_id].size.x, image_pool[image_id].size.y};
+  return image_pool[image_id]->size;
 }
 
 void Window::unload_image(int image_id) {
@@ -93,7 +98,7 @@ void Window::unload_image(int image_id) {
     return;
   }
 
-  SDL_DestroyTexture(image_pool[image_id].texture);
+  SDL_DestroyTexture(image_pool[image_id]->texture);
   image_pool.release(image_id);
 }
 
@@ -115,7 +120,15 @@ int Window::load_font(const char *path, int font_size, bool bold, bool italic, b
 
   TTF_SetFontStyle(font, style);
 
-  return font_pool.acquire({font, pixel_art});
+  Font *f = new Font{font, pixel_art};
+  int id = font_pool.acquire(f);
+  font_pool.use(id);
+
+  return id;
+}
+
+void Window::use_font(int font_id) {
+  font_pool.use(font_id);
 }
 
 void Window::unload_font(int font_id) {
@@ -124,7 +137,7 @@ void Window::unload_font(int font_id) {
     return;
   }
 
-  TTF_CloseFont(font_pool[font_id].font);
+  TTF_CloseFont(font_pool[font_id]->font);
   font_pool.release(font_id);
 }
 
@@ -135,7 +148,7 @@ int Window::create_text(int font_id, const char *text, uint32_t length, Color co
   }
 
   SDL_Color sdl_color = {color.r, color.g, color.b, color.a};
-  SDL_Surface *surface = TTF_RenderText_Solid(font_pool[font_id].font, text, length, sdl_color);
+  SDL_Surface *surface = TTF_RenderText_Solid(font_pool[font_id]->font, text, length, sdl_color);
 
   if (surface == nullptr) {
     fprintf(stderr, "Failed to create text surface: %s\n", SDL_GetError());
@@ -150,10 +163,17 @@ int Window::create_text(int font_id, const char *text, uint32_t length, Color co
     return UINT32_MAX;
   }
 
-  if (font_pool[font_id].pixel_art)
+  if (font_pool[font_id]->pixel_art)
     SDL_SetTextureScaleMode(texture, SDL_SCALEMODE_NEAREST);
 
-  return text_pool.acquire(texture);
+  float w, h;
+  SDL_GetTextureSize(texture, &w, &h);
+
+  Text *t = new Text{texture, {w, h}};
+  int id = text_pool.acquire(t);
+  text_pool.use(id);
+
+  return id;
 }
 
 Vec2<float> Window::get_text_size(int text_id) {
@@ -161,9 +181,7 @@ Vec2<float> Window::get_text_size(int text_id) {
     fprintf(stderr, "Invalid text ID: %d\n", text_id);
     return {0, 0};
   }
-  float w, h;
-  SDL_GetTextureSize(text_pool[text_id], &w, &h);
-  return {w, h};
+  return text_pool[text_id]->size;
 }
 
 void Window::unload_text(int text_id) {
@@ -172,7 +190,7 @@ void Window::unload_text(int text_id) {
     return;
   }
 
-  SDL_DestroyTexture(text_pool[text_id]);
+  SDL_DestroyTexture(text_pool[text_id]->texture);
   text_pool.release(text_id);
 }
 
@@ -275,7 +293,8 @@ void Window::render() {
   for (const RenderInstruction &instruction : render_instructions) {
     switch (instruction.type) {
     case RenderInstruction::DRAW_TEXT: {
-      SDL_Texture *texture = text_pool[instruction.draw_text.text_id];
+      Text *text = text_pool[instruction.draw_text.text_id];
+      SDL_Texture *texture = text->texture;
 
       SDL_FlipMode flip = SDL_FLIP_NONE;
 
@@ -287,14 +306,12 @@ void Window::render() {
       float scale_x = std::abs(instruction.scale.x) * scale;
       float scale_y = std::abs(instruction.scale.y) * scale;
 
-      float w, h;
-      SDL_GetTextureSize(texture, &w, &h);
-
       SDL_FRect dst_rect;
       dst_rect.x = instruction.draw_text.position.x * scale + offset.x;
       dst_rect.y = instruction.draw_text.position.y * scale + offset.y;
-      dst_rect.w = scale_x * w;
-      dst_rect.h = scale_y * h;
+
+      dst_rect.w = scale_x * text->size.x;
+      dst_rect.h = scale_y * text->size.y;
 
       SDL_RenderTextureRotated(
         renderer,
@@ -308,7 +325,7 @@ void Window::render() {
     } break;
 
     case RenderInstruction::DRAW_IMAGE: {
-      Image image = image_pool[instruction.draw_image.image_id];
+      Image *image = image_pool[instruction.draw_image.image_id];
 
       SDL_FlipMode flip = SDL_FLIP_NONE;
 
@@ -323,12 +340,12 @@ void Window::render() {
       SDL_FRect dst_rect;
       dst_rect.x = instruction.draw_image.position.x * scale + offset.x;
       dst_rect.y = instruction.draw_image.position.y * scale + offset.y;
-      dst_rect.w = scale_x * image.size.x;
-      dst_rect.h = scale_y * image.size.y;
+      dst_rect.w = scale_x * image->size.x;
+      dst_rect.h = scale_y * image->size.y;
 
       SDL_RenderTextureRotated(
         renderer,
-        image.texture,
+        image->texture,
         nullptr,
         &dst_rect,
         instruction.angle,