Lay the basic structure

.gitignore

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+build*/
+.vscode/

meson.build

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+project(
+    'jujube',
+    'cpp',
+    default_options : ['cpp_std=c++17'],
+    version : '0.1.0-alpha',
+)
+
+sfml = []
+foreach module : ['system', 'window', 'graphics', 'audio'] 
+    sfml += [dependency('sfml-'+module, version : '>=2.5.1')]
+endforeach
+
+executable(
+    'jujube',
+    'src/Main.cpp',
+    dependencies: sfml
+)

src/Main.cpp

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+#include <iostream>
+#include <SFML/Graphics.hpp>
+
+int main(int argc, char const *argv[])
+{
+
+    sf::RenderWindow window(sf::VideoMode(800,600), "jujube");
+    window.setVerticalSyncEnabled(true);
+    
+    bool fullscreen = false;
+    while (window.isOpen())
+    {
+        sf::Event event;
+        while (window.pollEvent(event))
+        {
+            switch (event.type)
+            {
+            case sf::Event::KeyPressed:
+                switch (event.key.code)
+                {
+                case sf::Keyboard::Enter:
+                    if (event.key.alt)
+                    {
+                        window.close();
+                        if (fullscreen)
+                        {
+                            window.create(sf::VideoMode(800,600), "jujube");
+                        } else {
+                            auto width = sf::VideoMode::getDesktopMode().width;
+                            auto height = sf::VideoMode::getDesktopMode().height;
+                            window.create(sf::VideoMode(width,height), "jujube", sf::Style::Fullscreen);
+                        }
+                        fullscreen = not fullscreen;
+                    } 
+                    break;
+                default:
+                    break;
+                }
+                break;
+            case sf::Event::Closed:
+                window.close();
+                break;
+            default:
+                break;
+            }
+        }
+        window.clear(sf::Color::Black);
+        window.display();
+    }
+    return 0;
+}