Hot reloading now works and you can toggle fullscreen so you can work on your presentation by just editing the file.

sample/about-bezos.md

@@ -1,7 +1,7 @@
 {
   "title": "How to use Bezos",
   "description": "A short presentation on Bezos.",
-  "font_file": "assets/text.otf"
+  "font_file": "assets/bold.otf"
 }
 ===
 # Bezos Slide Format
@@ -31,6 +31,7 @@ Bare content like this
 * { "bg_color": [r,g,b,a] }
 * Same as deck header
 * Put before the content
+* It works
 ---
 { "bg_image": "assets/sample_bg.jpg" }
 
@@ -62,3 +63,7 @@ One Word
 * Text will go over image
 * Image will stretch to fill
 ---
+# Hot Reload
+* It watches the file and
+  reloads when it changes
+---

src/control_ui.cpp

@@ -13,9 +13,9 @@
 #include "control_ui.hpp"
 
 ControlUI::ControlUI(sf::RenderWindow& presenter) :
-    $presenter(presenter)
+    $presenter(presenter),
+    $window_size($presenter.getSize())
 {
-
   $gui.position(0, 0, CONTROL_WIDTH, CONTROL_HEIGHT);
   $gui.layout(
       "[status|=%(100,100)current]"
@@ -28,7 +28,7 @@ void ControlUI::init() {
   $gui.set<guecs::Text>(status_id, {L""});
 
   auto docs_id = $gui.entity("docs");
-  $gui.set<guecs::Text>(docs_id, {L"A: win left\nD: win right\nQ: quit"});
+  $gui.set<guecs::Text>(docs_id, {L"F: fullscreen\nA: win left\nD: win right\nQ: quit"});
 
   auto current = $gui.entity("current");
   $gui.set<guecs::Rectangle>(current, {});
@@ -68,21 +68,29 @@ void ControlUI::handle_events(sf::RenderWindow& controller, const sf::Event& eve
 
   if(const auto* key = event.getIf<sf::Event::KeyPressed>()) {
     auto pos = $presenter.getPosition();
-    auto size = $presenter.getSize();
 
     using KEY = sf::Keyboard::Scan;
     switch(key->scancode) {
       case KEY::A: {
-          pos.x -= size.x;
+          pos.x -= $window_size.x;
           $presenter.setPosition(pos);
         } break;
       case KEY::D: {
-        pos.x += int(size.x);
+        pos.x += int($window_size.x);
         $presenter.setPosition(pos);
        } break;
       case KEY::Q:
         controller.close();
         break;
+      case KEY::F:
+        if($full_screen) {
+          $presenter.setSize({$window_size.x/2, $window_size.y/2});
+        } else {
+          $presenter.setSize($window_size);
+        }
+
+        $full_screen = !$full_screen;
+        break;
       default:
         break;
     }

src/control_ui.hpp

@@ -5,9 +5,11 @@
 #include "slides_ui.hpp"
 
 struct ControlUI {
+  bool $full_screen = true;
   guecs::UI $gui;
   guecs::Text* $status;
   sf::RenderWindow& $presenter;
+  sf::Vector2u $window_size;
 
   ControlUI(sf::RenderWindow& presenter);
   void init();

src/main.cpp

@@ -6,19 +6,61 @@
 #include "slides_ui.hpp"
 #include "control_ui.hpp"
 #include "parser.hpp"
+#include <filesystem>
+#include <chrono>
+#include <SFML/System/Clock.hpp>
 
-int main(int argc, char *argv[]) {
-  dbc::check(argc >= 2, "USAGE: bezos my_fucking_slides.md");
+using namespace std::chrono_literals;
 
-  auto backend = std::make_shared<gui::Backend>();
-
-  auto data = parse_slides(argv[1], [&](nlohmann::json& config) {
+std::optional<SlidesUI> load_slides(const std::string& input_md, std::shared_ptr<gui::Backend> backend) {
+  try {
+    auto data = parse_slides(input_md, [&](nlohmann::json& config) {
         backend->set_font(config["font_file"]);
         guecs::init(backend.get());
     });
 
     fmt::println("FONT FILE: {}", backend->$font_file);
 
+    SlidesUI slides(data);
+    slides.init();
+
+    return slides;
+  } catch(...) {
+    fmt::println("ERROR!");
+    return std::nullopt;
+  }
+}
+
+struct ChangeDetector {
+  std::string input_md;
+  sf::Clock timer{};
+  std::filesystem::file_time_type last_mod_time = std::filesystem::last_write_time(input_md);
+
+  bool check_changed() {
+    if(timer.getElapsedTime().toDuration() > 500ms) {
+      try {
+        auto mod_time = std::filesystem::last_write_time(input_md);
+
+        if(last_mod_time < mod_time) {
+          last_mod_time = mod_time;
+          return true;
+        } else {
+          return false;
+        }
+      } catch(const std::filesystem::filesystem_error& err) {
+        fmt::println("failed to open {}: {}", err.path1().string(), err.what());
+        timer.restart();
+        return false;
+      }
+    }
+
+    return false;
+  }
+};
+
+int main(int argc, char *argv[]) {
+  dbc::check(argc >= 2, "USAGE: bezos my_fucking_slides.md");
+
   auto& modes = sf::VideoMode::getFullscreenModes();
   auto screen_mode = std::find_if(modes.begin(), modes.end(), [=](const auto& a) -> bool {
       return a.size.x == WINDOW_WIDTH && a.size.y == WINDOW_HEIGHT;
@@ -32,25 +74,26 @@ int main(int argc, char *argv[]) {
   presenter.setFramerateLimit(FRAME_LIMIT);
   presenter.setVerticalSyncEnabled(VSYNC);
 
-  SlidesUI slides(data);
-  slides.init();
+  auto backend = std::make_shared<gui::Backend>();
+
+  auto new_slides = load_slides(argv[1], backend);
+
+  if(!new_slides) {
+    fmt::println("ERROR in your .md file");
+    return 1;
+  }
 
+  SlidesUI slides = *new_slides;
   ControlUI control_ui(presenter);
   control_ui.init();
 
   dbc::check(control_ui.$status != nullptr, "bad ptr");
 
+  ChangeDetector reloader{argv[1]};
+
   while(controller.isOpen()) {
     while (const auto event = presenter.pollEvent()) {
-      if(const auto* mouse = event->getIf<sf::Event::MouseButtonPressed>()) {
-        sf::Vector2f pos = presenter.mapPixelToCoords(mouse->position);
-
-        if(mouse->button == sf::Mouse::Button::Left) {
-          slides.mouse(pos.x, pos.y, {1 << guecs::ModBit::left});
-        } else if(mouse->button == sf::Mouse::Button::Right) {
-          slides.mouse(pos.x, pos.y, {1 << guecs::ModBit::right});
-        }
-      }
+      if(event) slides.handle_events(presenter, *event);
     }
 
     while (const auto event = controller.pollEvent()) {
@@ -62,5 +105,14 @@ int main(int argc, char *argv[]) {
 
     presenter.display();
     controller.display();
+
+    if(reloader.check_changed()) {
+      auto new_slides = load_slides(argv[1], backend);
+
+      if(new_slides) {
+        new_slides->set_slide(slides.$current);
+        slides = *new_slides;
+      }
+    }
   }
 }

src/slides_ui.cpp

@@ -139,6 +139,11 @@ void SlidesUI::prev_slide() {
   }
 }
 
+void SlidesUI::set_slide(size_t index) {
+  $current = index < $deck->slides.size() ? index : 0;
+  show_slide();
+}
+
 void SlidesUI::show_slide() {
   auto& slide = current();
 
@@ -187,3 +192,15 @@ void SlidesUI::mouse(float x, float y, guecs::Modifiers mods) {
     prev_slide();
   }
 }
+
+void SlidesUI::handle_events(sf::RenderWindow& presenter, const sf::Event& event) {
+  if(const auto* mev = event.getIf<sf::Event::MouseButtonPressed>()) {
+    sf::Vector2f pos = presenter.mapPixelToCoords(mev->position);
+
+    if(mev->button == sf::Mouse::Button::Left) {
+      mouse(pos.x, pos.y, {1 << guecs::ModBit::left});
+    } else if(mev->button == sf::Mouse::Button::Right) {
+      mouse(pos.x, pos.y, {1 << guecs::ModBit::right});
+    }
+  }
+}

src/slides_ui.hpp

@@ -45,7 +45,9 @@ struct SlidesUI {
   void next_slide();
   void prev_slide();
   void show_slide();
+  void set_slide(size_t index);
   void render(sf::RenderWindow& window);
   void mouse(float x, float y, guecs::Modifiers mods);
   void set_text(const std::string& name);
+  void handle_events(sf::RenderWindow& presenter, const sf::Event& event);
 };