Introduce app::scene & support changing scenes

libs/app/include/psemek/app/app.hpp

@@ -1,5 +1,7 @@
 #pragma once
 
+#include <psemek/app/scene.hpp>
+
 #include <SDL2/SDL_keycode.h>
 
 #include <memory>
@@ -8,38 +10,24 @@ namespace psemek::app
 {
 
 	struct app
+		: scene
 	{
 		app(std::string const & name);
-		virtual ~app();
+		~app() override;
 
 		virtual bool running() const;
 
-		virtual void on_resize(int width, int height);
+		void on_resize(int width, int height) override;
-		virtual void on_focus_gained();
+		void on_quit() override;
-		virtual void on_focus_lost();
-		virtual void on_quit();
 
-		virtual void on_mouse_move(int x, int y);
+		void draw() override;
-		virtual void on_mouse_wheel(int delta);
-		virtual void on_left_button_down();
-		virtual void on_left_button_up();
-		virtual void on_middle_button_down();
-		virtual void on_middle_button_up();
-		virtual void on_right_button_down();
-		virtual void on_right_button_up();
-
-		virtual void on_key_down(SDL_Keycode key);
-		virtual void on_key_up(SDL_Keycode key);
 
 		void poll_events();
-
-		virtual void update();
-		virtual void draw();
-
 		void run();
 
-		void show_cursor(bool show);
+		scene * set_scene(scene * s);
 
+		void show_cursor(bool show);
 		float time() const;
 
 	private:

libs/app/include/psemek/app/scene.hpp

@@ -0,0 +1,35 @@
+#pragma once
+
+#include <SDL2/SDL_keycode.h>
+
+namespace psemek::app
+{
+
+	struct scene
+	{
+		virtual ~scene() = 0;
+
+		virtual void on_resize(int width, int height) {}
+		virtual void on_focus_gained() {}
+		virtual void on_focus_lost() {}
+		virtual void on_quit() {}
+
+		virtual void on_mouse_move(int x, int y) {}
+		virtual void on_mouse_wheel(int delta) {}
+		virtual void on_left_button_down() {}
+		virtual void on_left_button_up() {}
+		virtual void on_middle_button_down() {}
+		virtual void on_middle_button_up() {}
+		virtual void on_right_button_down() {}
+		virtual void on_right_button_up() {}
+
+		virtual void on_key_down(SDL_Keycode key) {}
+		virtual void on_key_up(SDL_Keycode key) {}
+
+		virtual void update() {}
+		virtual void draw() {}
+	};
+
+	inline scene::~scene() = default;
+
+}

libs/app/source/app.cpp

@@ -39,6 +39,8 @@ namespace psemek::app
 		SDL_Window * window = nullptr;
 		SDL_GLContext gl_context = nullptr;
 
+		scene * current_scene = nullptr;
+
 		bool running = false;
 
 		bool had_initial_resize = false;
@@ -97,73 +99,53 @@ namespace psemek::app
 		gl::Viewport(0, 0, width, height);
 	}
 
-	void app::on_focus_gained() {}
-
-	void app::on_focus_lost() {}
-
 	void app::on_quit()
 	{
 		impl().running = false;
 	}
 
-	void app::on_mouse_move(int, int) {}
-
-	void app::on_mouse_wheel(int) {}
-
-	void app::on_left_button_down() {}
-
-	void app::on_left_button_up() {}
-
-	void app::on_middle_button_down() {}
-
-	void app::on_middle_button_up() {}
-
-	void app::on_right_button_down() {}
-
-	void app::on_right_button_up() {}
-
-	void app::on_key_down(SDL_Keycode) {}
-
-	void app::on_key_up(SDL_Keycode) {}
-
 	void app::poll_events()
 	{
+		scene * handler = this;
+		if (impl().current_scene)
+			handler = impl().current_scene;
+
 		for (SDL_Event e; SDL_PollEvent(&e);) switch (e.type)
 		{
 		case SDL_QUIT:
-			on_quit();
+			handler->on_quit();
 			break;
 		case SDL_WINDOWEVENT: switch (e.window.event)
 			{
 			case SDL_WINDOWEVENT_RESIZED:
 				impl().had_initial_resize = true;
-				on_resize(e.window.data1, e.window.data2);
+				handler->on_resize(e.window.data1, e.window.data2);
 				break;
 			case SDL_WINDOWEVENT_FOCUS_GAINED:
-				on_focus_gained();
+				handler->on_focus_gained();
 				break;
 			case SDL_WINDOWEVENT_FOCUS_LOST:
-				on_focus_lost();
+				handler->on_focus_lost();
 				break;
 			}
 			break;
 		case SDL_MOUSEMOTION:
-			on_mouse_move(e.motion.x, e.motion.y);
+			handler->on_mouse_move(e.motion.x, e.motion.y);
 			break;
 		case SDL_MOUSEWHEEL:
-			on_mouse_wheel(e.wheel.y);
+			handler->on_mouse_wheel(e.wheel.y);
 			break;
 		case SDL_MOUSEBUTTONDOWN:
 			switch (e.button.button)
 			{
 			case SDL_BUTTON_LEFT:
-				on_left_button_down();
+				handler->on_left_button_down();
 				break;
 			case SDL_BUTTON_MIDDLE:
-				on_middle_button_down();
+				handler->on_middle_button_down();
 				break;
 			case SDL_BUTTON_RIGHT:
-				on_right_button_down();
+				handler->on_right_button_down();
 				break;
 			}
 			break;
@@ -171,28 +153,25 @@ namespace psemek::app
 			switch (e.button.button)
 			{
 			case SDL_BUTTON_LEFT:
-				on_left_button_up();
+				handler->on_left_button_up();
 				break;
 			case SDL_BUTTON_MIDDLE:
-				on_middle_button_up();
+				handler->on_middle_button_up();
 				break;
 			case SDL_BUTTON_RIGHT:
-				on_right_button_up();
+				handler->on_right_button_up();
 				break;
 			}
 			break;
 		case SDL_KEYDOWN:
-			on_key_down(e.key.keysym.sym);
+			handler->on_key_down(e.key.keysym.sym);
 			break;
 		case SDL_KEYUP:
-			on_key_up(e.key.keysym.sym);
+			handler->on_key_up(e.key.keysym.sym);
 			break;
 		}
 	}
 
-	void app::update()
-	{}
-
 	void app::draw()
 	{
 		gl::ClearColor(0.7f, 0.7f, 1.f, 1.f);
@@ -220,6 +199,14 @@ namespace psemek::app
 		}
 	}
 
+	scene * app::set_scene(scene * s)
+	{
+		impl().had_initial_resize = false;
+
+		std::swap(s, impl().current_scene);
+		return s;
+	}
+
 	void app::show_cursor(bool show)
 	{
 		SDL_ShowCursor(show ? SDL_TRUE : SDL_FALSE);