A bit of cleanup and testing of the panel, then some optimization to avoid re-rendering and multiple wchar converts.

gui.cpp

@@ -201,9 +201,19 @@ void GUI::shake() {
 void GUI::render_scene() {
   $renderer.clear();
 
-  $renderer.draw_text_ui($status_ui);
+  $renderer.draw_text_ui($status_ui, true);
   $renderer.draw_screen($map_view);
 
+  /*
+  Panel prompt(30, 10, GAME_MAP_POS + 30, 200);
+  prompt.set_renderer([&] {
+    return hbox({
+        hflow(vbox(text("GOLD!")))
+        });
+    });
+  $renderer.draw_text_ui(prompt, true);
+  */
+
   $renderer.display();
 }
 

panel.cpp

@@ -1,24 +1,31 @@
 #include "panel.hpp"
 
 void Panel::resize(int width, int height) {
+  $dirty = true;
   $screen = Screen(width, height);
 }
 
 void Panel::set_renderer(std::function< Element()> render) {
+  $dirty = true;
   $component = Renderer(render);
 }
 
-Screen &Panel::render() {
+void Panel::render() {
+  $dirty = true;
   if($must_clear) $screen.Clear();
   Render($screen, $component->Render());
-  return $screen;
 }
 
-std::wstring Panel::to_string() {
-  std::string screenout = $screen.ToString();
-  return $converter.from_bytes(screenout);
+const std::wstring& Panel::to_string() {
+  if($dirty) {
+    std::string as_text = $screen.ToString();
+    $screenout = $converter.from_bytes(as_text);
+    $dirty = false;
+  }
+
+  return $screenout;
 }
 
-Screen &Panel::screen() {
+const Screen &Panel::screen() {
   return $screen;
 }

panel.hpp

@@ -17,6 +17,8 @@ struct Panel {
   int y;
   int width;
   int height;
+  std::wstring $screenout;
+  bool $dirty = true;
   Component $component;
   Screen $screen;
   bool $must_clear = true;
@@ -33,7 +35,7 @@ struct Panel {
 
   void resize(int width, int height);
   void set_renderer(std::function< Element()> render);
-  Screen &render();
-  std::wstring to_string();
-  Screen &screen();
+  void render();
+  const std::wstring &to_string();
+  const Screen &screen();
 };

render.cpp

@@ -104,7 +104,7 @@ inline void configure_tile(const sf::Sprite &sprite, sf::FloatRect &sp_bounds,
   height_delta = bg_bounds.height > sp_bounds.width ? (bg_bounds.height - sp_bounds.height) / 2 : 0;
 }
 
-void SFMLRender::render_text(std::wstring &text, float x, float y) {
+void SFMLRender::render_text(const std::wstring &text, float x, float y) {
   wchar_t last_tile = '#';
   sf::FloatRect sp_bounds;
   float width_delta = 0;
@@ -142,17 +142,23 @@ void SFMLRender::render_text(std::wstring &text, float x, float y) {
   });
 }
 
-void SFMLRender::draw_text_ui(Panel &panel) {
+void SFMLRender::draw_text_ui(Panel &panel, bool with_border) {
   sf::RectangleShape backing(
       sf::Vector2f($ui_bounds.width * panel.width,
         $ui_bounds.height * panel.height));
 
   backing.setFillColor(sf::Color(0, 0, 0));
+
+  if(with_border) {
+    backing.setOutlineColor(color(Value::MID));
+    backing.setOutlineThickness(5);
+  }
+
   backing.setPosition(panel.x, panel.y);
   $window.draw(backing);
 
   panel.render();
-  std::wstring panelout = panel.to_string();
+  const std::wstring &panelout = panel.to_string();
   $ui_text.setPosition(panel.x, panel.y);
   $ui_text.setString(panelout);
   $window.draw($ui_text);
@@ -160,6 +166,6 @@ void SFMLRender::draw_text_ui(Panel &panel) {
 
 void SFMLRender::draw_screen(Panel &panel, float x, float y) {
   panel.render();
-  std::wstring panelout = panel.to_string();
+  const std::wstring &panelout = panel.to_string();
   render_text(panelout, panel.x + x, panel.y + y);
 }

render.hpp

@@ -55,8 +55,8 @@ struct SFMLRender {
   sf::Color color(Value val);
   sf::Sprite &get_text_sprite(wchar_t tile);
   bool resize_map(int new_size, Point &view_port);
-  void render_text(std::wstring &text, float x, float y);
-  void draw_text_ui(Panel &panel);
+  void render_text(const std::wstring &text, float x, float y);
+  void draw_text_ui(Panel &panel, bool with_border=false);
   void draw_screen(Panel &panel, float map_off_x=0.0f, float map_off_y=0.0f);
 
   bool poll_event(sf::Event &event) {