From bb6551e5dc238ca742a82810632e7bd4c4e5f50b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Joshua=20Vanda=C3=ABle?= <joshua@vandaele.software>
Date: Mon, 15 Jun 2026 16:42:16 +0200
Subject: [PATCH] SDLGamepad: Support multiple touchpads

---
 .../ControllerInterface/SDL/SDLGamepad.cpp    | 22 ++++++----
 .../ControllerInterface/SDL/SDLGamepad.h      | 43 +++++++++++--------
 2 files changed, 38 insertions(+), 27 deletions(-)

diff --git a/Source/Core/InputCommon/ControllerInterface/SDL/SDLGamepad.cpp b/Source/Core/InputCommon/ControllerInterface/SDL/SDLGamepad.cpp
index 09457598c6..3de2518212 100644
--- a/Source/Core/InputCommon/ControllerInterface/SDL/SDLGamepad.cpp
+++ b/Source/Core/InputCommon/ControllerInterface/SDL/SDLGamepad.cpp
@@ -104,15 +104,21 @@ Gamepad::Gamepad(SDL_Gamepad* const gamepad, SDL_Joystick* const joystick)
     }
 
     // Touchpad
-    if (SDL_GetNumGamepadTouchpads(m_gamepad) > 0)
+    const int num_touchpads = SDL_GetNumGamepadTouchpads(m_gamepad);
+    if (num_touchpads > 0)
     {
-      const char* const name_x = "Touchpad X";
-      AddInput(new NonDetectableDirectionalInput<-1>(name_x, &m_touchpad_x));
-      AddInput(new NonDetectableDirectionalInput<+1>(name_x, &m_touchpad_x));
-      const char* const name_y = "Touchpad Y";
-      AddInput(new NonDetectableDirectionalInput<-1>(name_y, &m_touchpad_y));
-      AddInput(new NonDetectableDirectionalInput<+1>(name_y, &m_touchpad_y));
-      AddInput(new NormalizedInput("Touchpad Pressure", &m_touchpad_pressure));
+      m_touchpads.resize(num_touchpads);
+      for (int t = 0; t < num_touchpads; ++t)
+      {
+        // We do not number the first touchpad to keep backwards compatibility with existing configs
+        // that use "Touchpad X" and "Touchpad Y" as input names.
+        const std::string prefix = t > 0 ? fmt::format("Touchpad {} ", t + 1) : "Touchpad ";
+        AddInput(new NonDetectableDirectionalInput<-1>(prefix + "X", &m_touchpads[t].x));
+        AddInput(new NonDetectableDirectionalInput<+1>(prefix + "X", &m_touchpads[t].x));
+        AddInput(new NonDetectableDirectionalInput<-1>(prefix + "Y", &m_touchpads[t].y));
+        AddInput(new NonDetectableDirectionalInput<+1>(prefix + "Y", &m_touchpads[t].y));
+        AddInput(new NormalizedInput(prefix + "Pressure", &m_touchpads[t].pressure));
+      }
     }
 
     // Motion
diff --git a/Source/Core/InputCommon/ControllerInterface/SDL/SDLGamepad.h b/Source/Core/InputCommon/ControllerInterface/SDL/SDLGamepad.h
index 0a431866e7..6faa24b559 100644
--- a/Source/Core/InputCommon/ControllerInterface/SDL/SDLGamepad.h
+++ b/Source/Core/InputCommon/ControllerInterface/SDL/SDLGamepad.h
@@ -42,6 +42,13 @@ static_assert(GetDirectionFromHatMask(SDL_HAT_LEFT) == 3);
 namespace ciface::SDL
 {
 
+struct TouchpadState
+{
+  float x = 0.f;
+  float y = 0.f;
+  float pressure = 0.f;
+};
+
 class Gamepad : public Core::Device
 {
 private:
@@ -262,15 +269,15 @@ private:
   class NormalizedInput : public Input
   {
   public:
-    NormalizedInput(const char* name, const float* state) : m_name{std::move(name)}, m_state{*state}
+    NormalizedInput(std::string name, const float* state) : m_name{std::move(name)}, m_state{*state}
     {
     }
 
-    std::string GetName() const override { return std::string{m_name}; }
+    std::string GetName() const override { return m_name; }
     ControlState GetState() const override { return m_state; }
 
   private:
-    const char* const m_name;
+    const std::string m_name;
     const float& m_state;
   };
 
@@ -278,17 +285,17 @@ private:
   class NonDetectableDirectionalInput : public Input
   {
   public:
-    NonDetectableDirectionalInput(const char* name, const float* state)
+    NonDetectableDirectionalInput(std::string name, const float* state)
         : m_name{std::move(name)}, m_state{*state}
     {
     }
 
-    std::string GetName() const override { return std::string{m_name} + (Scale > 0 ? '+' : '-'); }
+    std::string GetName() const override { return m_name + (Scale > 0 ? '+' : '-'); }
     bool IsDetectable() const override { return false; }
     ControlState GetState() const override { return m_state * Scale; }
 
   private:
-    const char* const m_name;
+    const std::string m_name;
     const float& m_state;
   };
 
@@ -326,17 +333,17 @@ public:
   {
     UpdateBatteryLevel();
 
-    // We only support one touchpad and one finger.
-    const int touchpad_index = 0;
-    const int finger_index = 0;
-
-    if (SDL_GetNumGamepadTouchpads(m_gamepad) > touchpad_index &&
-        SDL_GetNumGamepadTouchpadFingers(m_gamepad, touchpad_index) > finger_index)
+    // We only support one finger per touchpad
+    static constexpr int finger_index = 0;
+    for (int t = 0; t < static_cast<int>(m_touchpads.size()); ++t)
     {
-      SDL_GetGamepadTouchpadFinger(m_gamepad, touchpad_index, finger_index, nullptr, &m_touchpad_x,
-                                   &m_touchpad_y, &m_touchpad_pressure);
-      m_touchpad_x = m_touchpad_x * 2 - 1;
-      m_touchpad_y = m_touchpad_y * 2 - 1;
+      if (SDL_GetNumGamepadTouchpadFingers(m_gamepad, t) <= finger_index)
+        continue;
+
+      SDL_GetGamepadTouchpadFinger(m_gamepad, t, finger_index, nullptr, &m_touchpads[t].x,
+                                   &m_touchpads[t].y, &m_touchpads[t].pressure);
+      m_touchpads[t].x = m_touchpads[t].x * 2 - 1;
+      m_touchpads[t].y = m_touchpads[t].y * 2 - 1;
     }
 
     return Core::DeviceRemoval::Keep;
@@ -366,9 +373,7 @@ private:
   SDL_Joystick* const m_joystick;
   SDL_Haptic* m_haptic = nullptr;
   ControlState m_battery_value;
-  float m_touchpad_x = 0.f;
-  float m_touchpad_y = 0.f;
-  float m_touchpad_pressure = 0.f;
+  std::vector<TouchpadState> m_touchpads;
 };
 
 struct SDLMotionAxis