Brought the UIStack over from the previous game to use here.

demos/multiscreen.cpp

@@ -0,0 +1,123 @@
+#include "guecs/sfml/backend.hpp"
+#include "guecs/sfml/components.hpp"
+#include "guecs/uistack.hpp"
+#include "guecs/ui.hpp"
+#include <iostream>
+#include <chrono>
+#include <thread>
+#include <flat_map>
+#include <fmt/core.h>
+
+using namespace std::chrono_literals;
+
+struct TestScreen {
+  guecs::UI $gui{};
+
+  TestScreen(const std::string &layout) {
+    init(layout);
+  }
+
+  void init(const std::string& layout) {
+    $gui.position(0, 0, 1280, 720);
+    $gui.layout(layout);
+
+    for(auto& [name, cell] : $gui.cells()) {
+      auto gui_id = $gui.entity(name);
+      $gui.set<guecs::Rectangle>(gui_id, {});
+      $gui.set<guecs::Effect>(gui_id, {});
+      $gui.set<guecs::Text>(gui_id, {guecs::to_wstring(name)});
+      $gui.set<guecs::Clickable>(gui_id, {
+          [&, gui_id, name](auto) { fmt::println("click! {}={}", name, gui_id); }
+      });
+    }
+
+    $gui.init();
+  }
+
+  void render(sf::RenderTarget& target) {
+    $gui.render(target);
+  }
+
+  bool mouse(float x, float y, guecs::Modifiers mods) {
+    return $gui.mouse(x, y, mods);
+  }
+
+  void update() {
+    // empty
+  }
+};
+
+
+int main() {
+  try {
+    sfml::Backend backend;
+    guecs::init(&backend);
+
+    sf::RenderWindow window(sf::VideoMode({1280, 720}), "Multi-Screen Tester");
+    window.setVerticalSyncEnabled(true);
+    window.setFramerateLimit(60);
+    window.setPosition({0,0});
+
+    gui::UIStack<TestScreen> stack;
+    auto test2 = std::make_shared<TestScreen>("[test2|sonice]");
+    auto test3 = std::make_shared<TestScreen>("[test3|pointer]");
+
+    {
+      stack.add("test1", std::make_shared<TestScreen>("[test1|hello]"));
+      stack.add("test2", test2);
+      stack.add("test3", test3);
+    }
+
+    stack.set_active("test1");
+
+    while(window.isOpen()) {
+      while (const auto event = window.pollEvent()) {
+        if(event->is<sf::Event::Closed>()) {
+          window.close();
+        }
+
+        if(const auto* mouse = event->getIf<sf::Event::MouseButtonPressed>()) {
+          if(mouse->button == sf::Mouse::Button::Left) {
+            sf::Vector2f pos = window.mapPixelToCoords(mouse->position);
+            stack.mouse(pos.x, pos.y, false);
+          }
+        } else if(const auto* key = event->getIf<sf::Event::KeyPressed>()) {
+          using KEY = sf::Keyboard::Scan;
+
+          switch(key->scancode) {
+            case KEY::Q:
+              return 0;
+            case KEY::N: {
+              bool good = stack.next();
+              fmt::println("showing {} is {}", stack.active_name(), good);
+              } break;
+            case KEY::P: {
+              bool good = stack.prev();
+              fmt::println("showing {} is {}", stack.active_name(), good);
+             } break;
+            case KEY::F:
+              stack.first();
+              break;
+            case KEY::L:
+              stack.last();
+              break;
+            default:
+              break;
+          }
+        }
+      }
+
+      stack.update();
+      stack.render(window);
+      window.display();
+
+      std::this_thread::sleep_for(100ms);
+    }
+
+  } catch(const std::system_error& e) {
+    std::cout << "WARNING: On OSX you'll get this error on shutdown.\n";
+    std::cout << "Caught system_error with code "
+                 "[" << e.code() << "] meaning "
+                 "[" << e.what() << "]\n";
+  }
+}