change Event to be more type safe, and prepare SDL3 migration

Author: jube

examples/19-gridmap.cc

@@ -204,10 +204,11 @@ namespace {
   private:
     void do_process_event(const gf::Event& event) override
     {
-      switch (event.type) {
+      switch (event.type()) {
         case gf::EventType::MouseMoved:
           {
-            auto mouse_position = event.mouse_motion.position;
+            const auto& mouse_motion_event = event.from<gf::EventType::MouseMoved>();
+            auto mouse_position = mouse_motion_event.position;
             auto mouse_location = position_to_world_location(mouse_position);
             gf::Vec2I position = m_grid_entity.grid().compute_position(mouse_location);
 

examples/20-physics.cc

@@ -23,7 +23,7 @@ namespace {
 
   int pixel(int x, int y)
   {
-    return (ImageBitmap[(x >> 3) + y * ImageRowLength] >> (~x & 0x07)) & 1; // NOLINT(cppcoreguidelines-pro-bounds-constant-array-index)
+    return (ImageBitmap[(x >> 3) + (y * ImageRowLength)] >> (~x & 0x07)) & 1; // NOLINT(cppcoreguidelines-pro-bounds-constant-array-index)
   }
 
   class PhysicsEntity : public gf::Entity {
@@ -116,8 +116,8 @@ namespace {
 
     void do_process_event(const gf::Event& event) override
     {
-      if (event.type == gf::EventType::KeyPressed) {
-        if (event.key.scancode == gf::Scancode::Space) {
+      if (event.type() == gf::EventType::KeyPressed) {
+        if (event.from<gf::EventType::KeyPressed>().scancode == gf::Scancode::Space) {
           m_entity.reset_world(m_random);
         }
       }

games/HOME/bits/WorldScene.cc

@@ -66,8 +66,8 @@ namespace home {
 
   void WorldScene::do_process_event(const gf::Event& event)
   {
-    if (event.type == gf::EventType::MouseButtonPressed) {
-      auto target = position_to_world_location(event.mouse_button.position);
+    if (event.type() == gf::EventType::MouseButtonPressed) {
+      auto target = position_to_world_location(event.from<gf::EventType::MouseButtonPressed>().position);
       gf::Log::debug("target: {}, {}", target.x, target.y);
       m_hero_entity.set_target(target);
     }

include/gf2/core/MouseTypes.h

@@ -24,6 +24,11 @@ namespace gf {
 
   constexpr MouseId TouchMouseId = static_cast<MouseId>(0xFFFFFFFF);
 
+  enum class MouseWheelDirection : uint32_t { // NOLINT(performance-enum-size)
+    Normal,
+    Flipped,
+  };
+
 } // namespace gf
 
 #endif // GF_MOUSE_TYPES_H