feat: draw frame only when needed, better main loop

include/window/wayland.h

@@ -16,6 +16,9 @@ public:
 	size_t GetHeight() const override;
 
 private:
+	void render_frame();
+
+private: // wayland listeners
   static void handle_frame_callback(void *data, struct wl_callback *cb,
                                     uint32_t time);
   static void xsurface_handle_configure(void *data, struct xdg_surface *surface,
@@ -32,7 +35,7 @@ private:
                                                struct xdg_toplevel *toplevel,
                                                struct wl_array *capabilities);
 
-private:
+private: // wayland internals
   EGLSurface m_egl_surface;
   EGLContext m_egl_context;
   GLuint m_program;
@@ -44,9 +47,13 @@ private:
   struct xdg_surface_listener m_xsurface_listener;
   struct xdg_toplevel_listener m_toplevel_listener;
 
+private:
 	bool m_running = false;
 	size_t m_width, m_height;
 
 	IFrameListener m_on_frame;
+
+	bool m_frame_cb_pending = false;
+	bool m_redraw_requested = false;
 };