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339 lines
14 KiB
C++
339 lines
14 KiB
C++
////////////////////////////////////////////////////////////
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// Headers
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////////////////////////////////////////////////////////////
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#include <SFML/Graphics.hpp>
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#include <vector>
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namespace
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{
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std::string vec2ToString(const sf::Vector2i vec2)
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{
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return '(' + std::to_string(vec2.x) + ", " + std::to_string(vec2.y) + ')';
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}
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} // namespace
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////////////////////////////////////////////////////////////
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/// \brief Application class
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///
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////////////////////////////////////////////////////////////
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class Application
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{
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public:
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////////////////////////////////////////////////////////////
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Application()
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{
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m_window.setVerticalSyncEnabled(true);
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m_logText.setFillColor(sf::Color::White);
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m_handlerText.setFillColor(sf::Color::White);
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m_handlerText.setStyle(sf::Text::Bold);
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m_handlerText.setPosition({380.f, 260.f});
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m_instructions.setFillColor(sf::Color::White);
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m_instructions.setStyle(sf::Text::Bold);
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m_instructions.setPosition({380.f, 310.f});
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}
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// The visitor we pass to event->visit in the "Visitor" handler
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// Make sure all defined operator()s return the same type.
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// The operator()s can also have void return type if there is nothing to return.
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struct Visitor
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{
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explicit Visitor(Application& app) : application(app)
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{
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}
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std::optional<std::string> operator()(const sf::Event::Closed&)
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{
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application.m_window.close();
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return std::nullopt;
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}
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std::optional<std::string> operator()(const sf::Event::KeyPressed& keyPress)
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{
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// When the enter key is pressed, switch to the next handler type
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if (keyPress.code == sf::Keyboard::Key::Enter)
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{
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application.m_handlerType = HandlerType::Overload;
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application.m_handlerText.setString("Current Handler: Overload");
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}
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return "Key Pressed: " + sf::Keyboard::getDescription(keyPress.scancode);
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}
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std::optional<std::string> operator()(const sf::Event::MouseMoved& mouseMoved)
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{
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return "Mouse Moved: " + vec2ToString(mouseMoved.position);
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}
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std::optional<std::string> operator()(const sf::Event::MouseButtonPressed&)
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{
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return "Mouse Pressed";
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}
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std::optional<std::string> operator()(const sf::Event::TouchBegan& touchBegan)
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{
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return "Touch Began: " + vec2ToString(touchBegan.position);
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}
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// When defining a visitor, make sure all event types can be handled by it.
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// If you don't intend on exhaustively specifying an operator() for each
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// event type, you can provide a templated operator() that will be selected
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// by overload resolution when no other event type matches.
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template <typename T>
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std::optional<std::string> operator()(const T&)
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{
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// All unhandled events will end up here
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// application.m_log.emplace_back("Other Event");
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return std::nullopt;
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}
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Application& application;
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};
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////////////////////////////////////////////////////////////
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void run()
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{
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// This example is for demonstration purposes only
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// All the following forms of event handling have equivalent behavior
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// In your own code you should decide which form of event handling
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// suits your needs best and use a single form of event handling
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while (m_window.isOpen())
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{
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if (m_handlerType == HandlerType::Classic)
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{
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// The "classical form" of event handling
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// Poll/Wait for events in a loop and handle them
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// individually based on their concrete type
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while (const std::optional event = m_window.pollEvent())
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{
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if (event->is<sf::Event::Closed>())
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{
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m_window.close();
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break;
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}
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if (const auto* keyPress = event->getIf<sf::Event::KeyPressed>())
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{
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m_log.emplace_back("Key Pressed: " + sf::Keyboard::getDescription(keyPress->scancode));
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// When the enter key is pressed, switch to the next handler type
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if (keyPress->code == sf::Keyboard::Key::Enter)
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{
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m_handlerType = HandlerType::Visitor;
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m_handlerText.setString("Current Handler: Visitor");
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}
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}
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else if (const auto* mouseMoved = event->getIf<sf::Event::MouseMoved>())
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{
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m_log.emplace_back("Mouse Moved: " + vec2ToString(mouseMoved->position));
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}
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else if (event->is<sf::Event::MouseButtonPressed>())
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{
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m_log.emplace_back("Mouse Pressed");
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}
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else if (const auto* touchBegan = event->getIf<sf::Event::TouchBegan>())
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{
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m_log.emplace_back("Touch Began: " + vec2ToString(touchBegan->position));
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}
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else
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{
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// All unhandled events will end up here
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// m_log.emplace_back("Other Event");
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}
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}
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}
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else if (m_handlerType == HandlerType::Visitor)
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{
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// Event Visitor
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// A visitor able to visit all event types is passed to the event
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// The visitor's defined operator()s can also return values
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while (const std::optional event = m_window.pollEvent())
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{
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if (std::optional logMessage = event->visit(Visitor(*this)))
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m_log.emplace_back(std::move(*logMessage));
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}
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}
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else if (m_handlerType == HandlerType::Overload)
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{
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// Overloaded visitation
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// A callable taking a concrete event type is provided per event type you want to handle
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m_window.handleEvents([&](const sf::Event::Closed&) { m_window.close(); },
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[&](const sf::Event::KeyPressed& keyPress)
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{
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m_log.emplace_back(
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"Key Pressed: " + sf::Keyboard::getDescription(keyPress.scancode));
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// When the enter key is pressed, switch to the next handler type
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if (keyPress.code == sf::Keyboard::Key::Enter)
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{
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m_handlerType = HandlerType::Generic;
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m_handlerText.setString("Current Handler: Generic");
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}
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},
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[&](const sf::Event::MouseMoved& mouseMoved)
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{ m_log.emplace_back("Mouse Moved: " + vec2ToString(mouseMoved.position)); },
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[&](const sf::Event::MouseButtonPressed&) { m_log.emplace_back("Mouse Pressed"); },
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[&](const sf::Event::TouchBegan& touchBegan)
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{ m_log.emplace_back("Touch Began: " + vec2ToString(touchBegan.position)); });
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// To handle unhandled events, just add the following lambda to the set of handlers
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// [&](const auto&) { m_log.emplace_back("Other Event"); }
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}
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else if (m_handlerType == HandlerType::Generic)
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{
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// Generic visitation
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// A generic callable is provided that can differentiate by deduced event type
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m_window.handleEvents(
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[&](auto&& event)
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{
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// Remove reference and cv-qualifiers
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using T = std::decay_t<decltype(event)>;
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if constexpr (std::is_same_v<T, sf::Event::Closed>)
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{
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m_window.close();
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}
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else if constexpr (std::is_same_v<T, sf::Event::KeyPressed>)
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{
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m_log.emplace_back("Key Pressed: " + sf::Keyboard::getDescription(event.scancode));
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// When the enter key is pressed, switch to the next handler type
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if (event.code == sf::Keyboard::Key::Enter)
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{
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m_handlerType = HandlerType::Forward;
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m_handlerText.setString("Current Handler: Forward");
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}
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}
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else if constexpr (std::is_same_v<T, sf::Event::MouseMoved>)
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{
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m_log.emplace_back("Mouse Moved: " + vec2ToString(event.position));
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}
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else if constexpr (std::is_same_v<T, sf::Event::MouseButtonPressed>)
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{
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m_log.emplace_back("Mouse Pressed");
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}
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else if constexpr (std::is_same_v<T, sf::Event::TouchBegan>)
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{
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m_log.emplace_back("Touch Began: " + vec2ToString(event.position));
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}
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else
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{
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// All unhandled events will end up here
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// m_log.emplace_back("Other Event");
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}
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});
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}
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else if (m_handlerType == HandlerType::Forward)
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{
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// Forward to other callable
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// In this case we forward it to our handle member functions
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// we defined for the concrete event types we want to handle
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// When choosing this method a default "catch-all" handler must
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// be available for unhandled events to be forwarded to
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// If you don't want to provide an empty "catch-all" handler
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// you will have to make sure (e.g. via if constexpr) that this
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// lambda doesn't attempt to call a member function that doesn't exist
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m_window.handleEvents([this](const auto& event) { handle(event); });
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}
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// Limit the log to 24 entries
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if (m_log.size() > 24u)
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m_log.erase(m_log.begin(), m_log.begin() + static_cast<int>(m_log.size() - 24u));
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// Draw the contents of the log to the window
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m_window.clear();
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for (std::size_t i = 0; i < m_log.size(); ++i)
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{
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m_logText.setPosition({50.f, static_cast<float>(i * 20) + 50.f});
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m_logText.setString(m_log[i]);
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m_window.draw(m_logText);
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}
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m_window.draw(m_handlerText);
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m_window.draw(m_instructions);
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m_window.display();
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}
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}
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// The following handle methods are called by the forwarding event handler implementation
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// A handle method is defined per event type you want to handle
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// To handle any other events that are left, the templated handle method will be called
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// Overload resolution will prefer the handle methods that fit the event type better
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// before falling back to the templated method
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void handle(const sf::Event::Closed&)
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{
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m_window.close();
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}
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void handle(const sf::Event::KeyPressed& keyPress)
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{
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m_log.emplace_back("Key Pressed: " + sf::Keyboard::getDescription(keyPress.scancode));
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// When the enter key is pressed, switch to the next handler type
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if (keyPress.code == sf::Keyboard::Key::Enter)
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{
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m_handlerType = HandlerType::Classic;
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m_handlerText.setString("Current Handler: Classic");
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}
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}
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void handle(const sf::Event::MouseMoved& mouseMoved)
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{
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m_log.emplace_back("Mouse Moved: " + vec2ToString(mouseMoved.position));
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}
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void handle(const sf::Event::MouseButtonPressed&)
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{
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m_log.emplace_back("Mouse Pressed");
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}
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void handle(const sf::Event::TouchBegan& touchBegan)
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{
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m_log.emplace_back("Touch Began: " + vec2ToString(touchBegan.position));
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}
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template <typename T>
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void handle(const T&)
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{
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// All unhandled events will end up here
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// m_log.emplace_back("Other Event");
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}
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private:
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enum class HandlerType
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{
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Classic,
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Visitor,
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Overload,
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Generic,
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Forward
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};
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////////////////////////////////////////////////////////////
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// Member data
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////////////////////////////////////////////////////////////
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sf::RenderWindow m_window{sf::VideoMode({800u, 600u}), "SFML Event Handling", sf::Style::Titlebar | sf::Style::Close};
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const sf::Font m_font{"resources/tuffy.ttf"};
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sf::Text m_logText{m_font, "", 20};
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sf::Text m_handlerText{m_font, "Current Handler: Classic", 24};
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sf::Text m_instructions{m_font, "Press Enter to change handler type", 24};
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std::vector<std::string> m_log;
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HandlerType m_handlerType{HandlerType::Classic};
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};
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////////////////////////////////////////////////////////////
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/// Entry point of application
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///
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/// \return Application exit code
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///
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////////////////////////////////////////////////////////////
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int main()
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{
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Application application;
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application.run();
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}
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