CommonHostInterface: Add controller nav helpers

src/frontend-common/common_host_interface.cpp

@@ -2866,6 +2866,12 @@ std::unique_ptr<ByteStream> CommonHostInterface::OpenPackageFile(const char* pat
   return FileSystem::OpenFile(full_path.c_str(), real_flags);
 }
 
+bool CommonHostInterface::SetControllerNavigationButtonState(FrontendCommon::ControllerNavigationButton button,
+                                                             bool pressed)
+{
+  return false;
+}
+
 #ifdef WITH_DISCORD_PRESENCE
 
 void CommonHostInterface::SetDiscordPresenceEnabled(bool enabled)

src/frontend-common/common_host_interface.h

@@ -19,7 +19,21 @@ class ControllerInterface;
 
 namespace FrontendCommon {
 class SaveStateSelectorUI;
-}
+
+enum class ControllerNavigationButton : u32
+{
+  Activate,      // A on XBox Controller, Cross on PS Controller
+  Cancel,        // B on XBox Controller, Circle on PS Controller
+  LeftShoulder,  // LB on XBox Controller, L1 on PS Controller
+  RightShoulder, // RB on XBox Controller, R1 on PS Controller
+  DPadLeft,
+  DPadRight,
+  DPadUp,
+  DPadDown,
+  Count
+};
+
+} // namespace FrontendCommon
 
 class CommonHostInterface : public HostInterface
 {
@@ -234,6 +248,10 @@ public:
   /// This is the APK for Android builds, or the program directory for standalone builds.
   virtual std::unique_ptr<ByteStream> OpenPackageFile(const char* path, u32 flags) override;
 
+  /// Controller navigation, used by fullscreen mode. Returns true if the UI consumed the event, and it should not
+  /// execute the normal handler.
+  bool SetControllerNavigationButtonState(FrontendCommon::ControllerNavigationButton button, bool pressed);
+
   /// Toggles fast forward state.
   bool IsFastForwardEnabled() const { return m_fast_forward_enabled; }
   void SetFastForwardEnabled(bool enabled);

src/frontend-common/sdl_controller_interface.cpp

@@ -673,10 +673,37 @@ bool SDLControllerInterface::HandleControllerButtonEvent(const SDL_ControllerBut
   if (it == m_controllers.end())
     return false;
 
+  static constexpr std::array<FrontendCommon::ControllerNavigationButton, SDL_CONTROLLER_BUTTON_MAX>
+    nav_button_mapping = {{
+      FrontendCommon::ControllerNavigationButton::Activate,      // SDL_CONTROLLER_BUTTON_A
+      FrontendCommon::ControllerNavigationButton::Cancel,        // SDL_CONTROLLER_BUTTON_B
+      FrontendCommon::ControllerNavigationButton::Count,         // SDL_CONTROLLER_BUTTON_X
+      FrontendCommon::ControllerNavigationButton::Count,         // SDL_CONTROLLER_BUTTON_Y
+      FrontendCommon::ControllerNavigationButton::Count,         // SDL_CONTROLLER_BUTTON_BACK
+      FrontendCommon::ControllerNavigationButton::Count,         // SDL_CONTROLLER_BUTTON_GUIDE
+      FrontendCommon::ControllerNavigationButton::Count,         // SDL_CONTROLLER_BUTTON_START
+      FrontendCommon::ControllerNavigationButton::Count,         // SDL_CONTROLLER_BUTTON_LEFTSTICK
+      FrontendCommon::ControllerNavigationButton::Count,         // SDL_CONTROLLER_BUTTON_RIGHTSTICK
+      FrontendCommon::ControllerNavigationButton::LeftShoulder,  // SDL_CONTROLLER_BUTTON_LEFTSHOULDER
+      FrontendCommon::ControllerNavigationButton::RightShoulder, // SDL_CONTROLLER_BUTTON_RIGHTSHOULDER
+      FrontendCommon::ControllerNavigationButton::DPadUp,        // SDL_CONTROLLER_BUTTON_DPAD_UP
+      FrontendCommon::ControllerNavigationButton::DPadDown,      // SDL_CONTROLLER_BUTTON_DPAD_DOWN
+      FrontendCommon::ControllerNavigationButton::DPadLeft,      // SDL_CONTROLLER_BUTTON_DPAD_LEFT
+      FrontendCommon::ControllerNavigationButton::DPadRight,     // SDL_CONTROLLER_BUTTON_DPAD_RIGHT
+    }};
+
   const bool pressed = (ev->state == SDL_PRESSED);
   if (DoEventHook(Hook::Type::Button, it->player_id, ev->button, pressed ? 1.0f : 0.0f))
     return true;
 
+  if (ev->button < nav_button_mapping.size() &&
+      nav_button_mapping[ev->button] != FrontendCommon::ControllerNavigationButton::Count &&
+      m_host_interface->SetControllerNavigationButtonState(nav_button_mapping[ev->button], pressed))
+  {
+    // UI consumed the event
+    return true;
+  }
+
   const ButtonCallback& cb = it->button_mapping[ev->button];
   if (cb)
   {