Rewrite sf::Event API to improve type safety

This new API is built on top of std::variant. This allows us to
store many different event types in a space-efficient way and access
the active event type in a type-safe manner that eliminates the
categories of UB that are possible with unions.

Co-authored-by: kimci86 <kimci86@hotmail.fr>

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -59,7 +59,7 @@ body:
                   {
                       for (sf::Event event; window.pollEvent(event);)
                       {
-                          if (event.type == sf::Event::Closed)
+                          if (event.is<sf::Event::Closed>())
                               window.close();
                       }
 

.github/ISSUE_TEMPLATE/feature_request.yml

@@ -56,7 +56,7 @@ body:
                   {
                       for (sf::Event event; window.pollEvent(event);)
                       {
-                          if (event.type == sf::Event::Closed)
+                          if (event.is<sf::Event::Closed>())
                               window.close();
                       }
 

.github/pull_request_template.md

@@ -41,7 +41,7 @@ int main()
     {
         for (sf::Event event; window.pollEvent(event);)
         {
-            if (event.type == sf::Event::Closed)
+            if (event.is<sf::Event::Closed>())
                 window.close();
         }
 

doc/mainpage.hpp

@@ -47,7 +47,7 @@
 ///         for (sf::Event event; window.pollEvent(event);)
 ///         {
 ///             // Close window: exit
-///             if (event.type == sf::Event::Closed)
+///             if (event.is<sf::Event::Closed>())
 ///                 window.close();
 ///         }
 ///

examples/android/app/src/main/jni/main.cpp

@@ -115,44 +115,50 @@ int main(int argc, char* argv[])
     {
         for (sf::Event event; active ? window.pollEvent(event) : window.waitEvent(event);)
         {
-            switch (event.type)
+            switch (event.getType())
             {
-                case sf::Event::Closed:
+                case sf::Event::Type::Closed:
                     window.close();
                     break;
-                case sf::Event::KeyPressed:
-                    if (event.key.code == sf::Keyboard::Key::Escape)
+                case sf::Event::Type::KeyPressed:
+                    if (event.get<sf::Event::KeyPressed>().code == sf::Keyboard::Key::Escape)
                         window.close();
                     break;
-                case sf::Event::Resized:
-                    view.setSize(sf::Vector2f(event.size.width, event.size.height));
-                    view.setCenter(sf::Vector2f(event.size.width, event.size.height) / 2.f);
+                case sf::Event::Type::Resized:
+                {
+                    const auto size = sf::Vector2f(event.get<sf::Event::Resized>().size);
+                    view.setSize(size);
+                    view.setCenter(size / 2.f);
                     window.setView(view);
                     break;
-                case sf::Event::LostFocus:
+                }
+                case sf::Event::Type::FocusLost:
                     background = sf::Color::Black;
                     break;
-                case sf::Event::GainedFocus:
+                case sf::Event::Type::FocusGained:
                     background = sf::Color::White;
                     break;
 
                 // On Android MouseLeft/MouseEntered are (for now) triggered,
                 // whenever the app loses or gains focus.
-                case sf::Event::MouseLeft:
+                case sf::Event::Type::MouseLeft:
                     active = false;
                     break;
-                case sf::Event::MouseEntered:
+                case sf::Event::Type::MouseEntered:
                     active = true;
                     break;
-                case sf::Event::TouchBegan:
-                    if (event.touch.finger == 0)
+                case sf::Event::Type::TouchBegan:
+                {
+                    const auto& touchBegan = event.get<sf::Event::TouchBegan>();
+                    if (touchBegan.finger == 0)
                     {
-                        image.setPosition({static_cast<float>(event.touch.x), static_cast<float>(event.touch.y)});
+                        image.setPosition(sf::Vector2f(touchBegan.position));
 #if defined(USE_JNI)
                         vibrate(sf::milliseconds(10));
 #endif
                     }
                     break;
+                }
                 default:
                     break;
             }

examples/island/Island.cpp

@@ -182,17 +182,17 @@ int main()
         for (sf::Event event; window.pollEvent(event);)
         {
             // Window closed or escape key pressed: exit
-            if ((event.type == sf::Event::Closed) ||
-                ((event.type == sf::Event::KeyPressed) && (event.key.code == sf::Keyboard::Key::Escape)))
+            if (event.is<sf::Event::Closed>() ||
+                (event.is<sf::Event::KeyPressed>() && event.get<sf::Event::KeyPressed>().code == sf::Keyboard::Key::Escape))
             {
                 window.close();
                 break;
             }
 
             // Arrow key pressed:
-            if (prerequisitesSupported && (event.type == sf::Event::KeyPressed))
+            if (prerequisitesSupported && event.is<sf::Event::KeyPressed>())
             {
-                switch (event.key.code)
+                switch (event.get<sf::Event::KeyPressed>().code)
                 {
                     case sf::Keyboard::Key::Enter:
                         generateTerrain(terrainStagingBuffer.data());

examples/joystick/Joystick.cpp

@@ -161,19 +161,33 @@ int main()
         for (sf::Event event; window.pollEvent(event);)
         {
             // Window closed or escape key pressed: exit
-            if ((event.type == sf::Event::Closed) ||
-                ((event.type == sf::Event::KeyPressed) && (event.key.code == sf::Keyboard::Key::Escape)))
+            if (event.is<sf::Event::Closed>() ||
+                (event.is<sf::Event::KeyPressed>() && event.get<sf::Event::KeyPressed>().code == sf::Keyboard::Key::Escape))
             {
                 window.close();
                 break;
             }
-            else if ((event.type == sf::Event::JoystickButtonPressed) || (event.type == sf::Event::JoystickButtonReleased) ||
-                     (event.type == sf::Event::JoystickMoved) || (event.type == sf::Event::JoystickConnected))
+            else if (const auto* joystickButtonPressed = event.getIf<sf::Event::JoystickButtonPressed>())
             {
                 // Update displayed joystick values
-                updateValues(event.joystickConnect.joystickId);
+                updateValues(joystickButtonPressed->joystickId);
             }
-            else if (event.type == sf::Event::JoystickDisconnected)
+            else if (const auto* joystickButtonReleased = event.getIf<sf::Event::JoystickButtonReleased>())
+            {
+                // Update displayed joystick values
+                updateValues(joystickButtonReleased->joystickId);
+            }
+            else if (const auto* joystickMoved = event.getIf<sf::Event::JoystickMoved>())
+            {
+                // Update displayed joystick values
+                updateValues(joystickMoved->joystickId);
+            }
+            else if (const auto* joystickConnected = event.getIf<sf::Event::JoystickConnected>())
+            {
+                // Update displayed joystick values
+                updateValues(joystickConnected->joystickId);
+            }
+            else if (event.is<sf::Event::JoystickDisconnected>())
             {
                 // Reset displayed joystick values to empty
                 for (auto& [label, joystickObject] : texts)

examples/opengl/OpenGL.cpp

@@ -211,21 +211,23 @@ int main()
             for (sf::Event event; window.pollEvent(event);)
             {
                 // Close window: exit
-                if (event.type == sf::Event::Closed)
+                if (event.is<sf::Event::Closed>())
                 {
                     exit = true;
                     window.close();
                 }
 
                 // Escape key: exit
-                if ((event.type == sf::Event::KeyPressed) && (event.key.code == sf::Keyboard::Key::Escape))
+                if (const auto* keyPressed = event.getIf<sf::Event::KeyPressed>();
+                    keyPressed && keyPressed->code == sf::Keyboard::Key::Escape)
                 {
                     exit = true;
                     window.close();
                 }
 
                 // Return key: toggle mipmapping
-                if ((event.type == sf::Event::KeyPressed) && (event.key.code == sf::Keyboard::Key::Enter))
+                if (const auto* keyPressed = event.getIf<sf::Event::KeyPressed>();
+                    keyPressed && keyPressed->code == sf::Keyboard::Key::Enter)
                 {
                     if (mipmapEnabled)
                     {
@@ -242,14 +244,15 @@ int main()
                 }
 
                 // Space key: toggle sRGB conversion
-                if ((event.type == sf::Event::KeyPressed) && (event.key.code == sf::Keyboard::Key::Space))
+                if (const auto* keyPressed = event.getIf<sf::Event::KeyPressed>();
+                    keyPressed && keyPressed->code == sf::Keyboard::Key::Space)
                 {
                     sRgb = !sRgb;
                     window.close();
                 }
 
                 // Adjust the viewport when the window is resized
-                if (event.type == sf::Event::Resized)
+                if (const auto* resized = event.getIf<sf::Event::Resized>())
                 {
                     const sf::Vector2u textureSize = backgroundTexture.getSize();
 
@@ -260,10 +263,11 @@ int main()
                         return EXIT_FAILURE;
                     }
 
-                    glViewport(0, 0, static_cast<GLsizei>(event.size.width), static_cast<GLsizei>(event.size.height));
+                    const auto [width, height] = resized->size;
+                    glViewport(0, 0, static_cast<GLsizei>(width), static_cast<GLsizei>(height));
                     glMatrixMode(GL_PROJECTION);
                     glLoadIdentity();
-                    const GLfloat newRatio = static_cast<float>(event.size.width) / static_cast<float>(event.size.height);
+                    const GLfloat newRatio = static_cast<float>(width) / static_cast<float>(height);
 #ifdef SFML_OPENGL_ES
                     glFrustumf(-newRatio, newRatio, -1.f, 1.f, 1.f, 500.f);
 #else

examples/shader/Shader.cpp

@@ -400,12 +400,12 @@ int main()
         for (sf::Event event; window.pollEvent(event);)
         {
             // Close window: exit
-            if (event.type == sf::Event::Closed)
+            if (event.is<sf::Event::Closed>())
                 window.close();
 
-            if (event.type == sf::Event::KeyPressed)
+            if (const auto* keyPressed = event.getIf<sf::Event::KeyPressed>())
             {
-                switch (event.key.code)
+                switch (keyPressed->code)
                 {
                     // Escape key: exit
                     case sf::Keyboard::Key::Escape:

examples/stencil/Stencil.cpp

@@ -43,7 +43,7 @@ int main()
         for (sf::Event event; window.pollEvent(event);)
         {
             // Window closed: exit
-            if (event.type == sf::Event::Closed)
+            if (event.is<sf::Event::Closed>())
             {
                 window.close();
                 break;

examples/tennis/Tennis.cpp

@@ -118,16 +118,16 @@ int main()
         for (sf::Event event; window.pollEvent(event);)
         {
             // Window closed or escape key pressed: exit
-            if ((event.type == sf::Event::Closed) ||
-                ((event.type == sf::Event::KeyPressed) && (event.key.code == sf::Keyboard::Key::Escape)))
+            if (event.is<sf::Event::Closed>() ||
+                (event.is<sf::Event::KeyPressed>() && event.get<sf::Event::KeyPressed>().code == sf::Keyboard::Key::Escape))
             {
                 window.close();
                 break;
             }
 
             // Space key pressed: play
-            if (((event.type == sf::Event::KeyPressed) && (event.key.code == sf::Keyboard::Key::Space)) ||
-                (event.type == sf::Event::TouchBegan))
+            if ((event.is<sf::Event::KeyPressed>() && event.get<sf::Event::KeyPressed>().code == sf::Keyboard::Key::Space) ||
+                event.is<sf::Event::TouchBegan>())
             {
                 if (!isPlaying)
                 {
@@ -150,7 +150,7 @@ int main()
             }
 
             // Window size changed, adjust view appropriately
-            if (event.type == sf::Event::Resized)
+            if (event.is<sf::Event::Resized>())
             {
                 sf::View view;
                 view.setSize({gameWidth, gameHeight});

examples/vulkan/Vulkan.cpp

@@ -2545,15 +2545,15 @@ class VulkanExample
             for (sf::Event event; window.pollEvent(event);)
             {
                 // Close window: exit
-                if (event.type == sf::Event::Closed)
+                if (event.is<sf::Event::Closed>())
                     window.close();
 
                 // Escape key: exit
-                if ((event.type == sf::Event::KeyPressed) && (event.key.code == sf::Keyboard::Key::Escape))
+                if (event.is<sf::Event::KeyPressed>() && event.get<sf::Event::KeyPressed>().code == sf::Keyboard::Key::Escape)
                     window.close();
 
                 // Re-create the swapchain when the window is resized
-                if (event.type == sf::Event::Resized)
+                if (event.is<sf::Event::Resized>())
                     swapchainOutOfDate = true;
             }
 

examples/window/Window.cpp

@@ -144,20 +144,21 @@ int main()
         for (sf::Event event; window.pollEvent(event);)
         {
             // Close window: exit
-            if (event.type == sf::Event::Closed)
+            if (event.is<sf::Event::Closed>())
                 window.close();
 
             // Escape key: exit
-            if ((event.type == sf::Event::KeyPressed) && (event.key.code == sf::Keyboard::Key::Escape))
+            if (event.is<sf::Event::KeyPressed>() && event.get<sf::Event::KeyPressed>().code == sf::Keyboard::Key::Escape)
                 window.close();
 
             // Resize event: adjust the viewport
-            if (event.type == sf::Event::Resized)
+            if (const auto* resized = event.getIf<sf::Event::Resized>())
             {
-                glViewport(0, 0, static_cast<GLsizei>(event.size.width), static_cast<GLsizei>(event.size.height));
+                const auto [width, height] = resized->size;
+                glViewport(0, 0, static_cast<GLsizei>(width), static_cast<GLsizei>(height));
                 glMatrixMode(GL_PROJECTION);
                 glLoadIdentity();
-                const GLfloat newRatio = static_cast<float>(event.size.width) / static_cast<float>(event.size.height);
+                const GLfloat newRatio = static_cast<float>(width) / static_cast<float>(height);
 #ifdef SFML_OPENGL_ES
                 glFrustumf(-newRatio, newRatio, -1.f, 1.f, 1.f, 500.f);
 #else

include/SFML/Graphics/RenderWindow.hpp

@@ -240,7 +240,7 @@ class SFML_GRAPHICS_API RenderWindow : public Window, public RenderTarget
 ///    for (sf::Event event; window.pollEvent(event);)
 ///    {
 ///        // Request for closing the window
-///        if (event.type == sf::Event::Closed)
+///        if (event.is<sf::Event::Closed>())
 ///            window.close();
 ///    }
 ///

include/SFML/Window/Clipboard.hpp

@@ -93,16 +93,17 @@ SFML_WINDOW_API void setString(const String& text);
 /// // or use it in the event loop
 /// for (sf::Event event; window.pollEvent(event);)
 /// {
-///     if(event.type == sf::Event::Closed)
+///     if(event.is<sf::Event::Closed>())
 ///         window.close();
-///     if(event.type == sf::Event::KeyPressed)
+///     if(event.is<sf::Event::KeyPressed>())
 ///     {
+///         const auto& keyPressed = event.get<sf::Event::KeyPressed>();
 ///         // Using Ctrl + V to paste a string into SFML
-///         if(event.key.control && event.key.code == sf::Keyboard::Key::V)
+///         if(keyPressed.control && keyPressed.code == sf::Keyboard::Key::V)
 ///             string = sf::Clipboard::getString();
 ///
 ///         // Using Ctrl + C to copy a string out of SFML
-///         if(event.key.control && event.key.code == sf::Keyboard::Key::C)
+///         if(keyPressed.control && keyPressed.code == sf::Keyboard::Key::C)
 ///             sf::Clipboard::setString("Hello World!");
 ///     }
 /// }