Backends: SDL3: Fixed gamepad. Added support for disconnection. Added support for multiple gamepads. Added ImGui_ImplSDL3_SetGamepadMode(). (#7180, #3884, #6559, #6890)

backends/imgui_impl_sdl3.cpp

@@ -22,6 +22,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2024-02-13: Inputs: Fixed gamepad support. Handle gamepad disconnection. Added ImGui_ImplSDL3_SetGamepadMode().
 //  2023-11-13: Updated for recent SDL3 API changes.
 //  2023-10-05: Inputs: Added support for extra ImGuiKey values: F13 to F24 function keys, app back/forward keys.
 //  2023-05-04: Fixed build on Emscripten/iOS/Android. (#6391)
@@ -74,6 +75,11 @@ struct ImGui_ImplSDL3_Data
     int                     MousePendingLeaveFrame;
     bool                    MouseCanUseGlobalState;
 
+    // Gamepad handling
+    ImVector<SDL_Gamepad*>      Gamepads;
+    ImGui_ImplSDL3_GamepadMode  GamepadMode;
+    bool                        WantUpdateGamepadsList;
+
     ImGui_ImplSDL3_Data()   { memset((void*)this, 0, sizeof(*this)); }
 };
 
@@ -332,6 +338,12 @@ bool ImGui_ImplSDL3_ProcessEvent(const SDL_Event* event)
         case SDL_EVENT_WINDOW_FOCUS_LOST:
             io.AddFocusEvent(false);
             return true;
+        case SDL_EVENT_GAMEPAD_ADDED:
+        case SDL_EVENT_GAMEPAD_REMOVED:
+        {
+            bd->WantUpdateGamepadsList = true;
+            return true;
+        }
     }
     return false;
 }
@@ -380,6 +392,10 @@ static bool ImGui_ImplSDL3_Init(SDL_Window* window, SDL_Renderer* renderer, void
     io.ClipboardUserData = nullptr;
     io.SetPlatformImeDataFn = ImGui_ImplSDL3_SetPlatformImeData;
 
+    // Gamepad handling
+    bd->GamepadMode = ImGui_ImplSDL3_GamepadMode_AutoFirst;
+    bd->WantUpdateGamepadsList = true;
+
     // Load mouse cursors
     bd->MouseCursors[ImGuiMouseCursor_Arrow] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_ARROW);
     bd->MouseCursors[ImGuiMouseCursor_TextInput] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_IBEAM);
@@ -447,6 +463,8 @@ bool ImGui_ImplSDL3_InitForOther(SDL_Window* window)
     return ImGui_ImplSDL3_Init(window, nullptr, nullptr);
 }
 
+static void ImGui_ImplSDL3_CloseGamepads();
+
 void ImGui_ImplSDL3_Shutdown()
 {
     ImGui_ImplSDL3_Data* bd = ImGui_ImplSDL3_GetBackendData();
@@ -457,7 +475,7 @@ void ImGui_ImplSDL3_Shutdown()
         SDL_free(bd->ClipboardTextData);
     for (ImGuiMouseCursor cursor_n = 0; cursor_n < ImGuiMouseCursor_COUNT; cursor_n++)
         SDL_DestroyCursor(bd->MouseCursors[cursor_n]);
-    bd->MouseLastCursor = nullptr;
+    ImGui_ImplSDL3_CloseGamepads();
 
     io.BackendPlatformName = nullptr;
     io.BackendPlatformUserData = nullptr;
@@ -525,50 +543,109 @@ static void ImGui_ImplSDL3_UpdateMouseCursor()
     }
 }
 
+static void ImGui_ImplSDL3_CloseGamepads()
+{
+    ImGui_ImplSDL3_Data* bd = ImGui_ImplSDL3_GetBackendData();
+    if (bd->GamepadMode != ImGui_ImplSDL3_GamepadMode_Manual)
+        for (SDL_Gamepad* gamepad : bd->Gamepads)
+            SDL_CloseGamepad(gamepad);
+    bd->Gamepads.resize(0);
+}
+
+void ImGui_ImplSDL3_SetGamepadMode(ImGui_ImplSDL3_GamepadMode mode, SDL_Gamepad** manual_gamepads_array, int manual_gamepads_count)
+{
+    ImGui_ImplSDL3_Data* bd = ImGui_ImplSDL3_GetBackendData();
+    ImGui_ImplSDL3_CloseGamepads();
+    if (mode == ImGui_ImplSDL3_GamepadMode_Manual)
+    {
+        IM_ASSERT(manual_gamepads_array != nullptr && manual_gamepads_count > 0);
+        for (int n = 0; n < manual_gamepads_count; n++)
+            bd->Gamepads.push_back(manual_gamepads_array[n]);
+    }
+    else
+    {
+        IM_ASSERT(manual_gamepads_array == nullptr && manual_gamepads_count <= 0);
+        bd->WantUpdateGamepadsList = true;
+    }
+    bd->GamepadMode = mode;
+}
+
+static void ImGui_ImplSDL3_UpdateGamepadButton(ImGui_ImplSDL3_Data* bd, ImGuiIO& io, ImGuiKey key, SDL_GamepadButton button_no)
+{
+    bool merged_value = false;
+    for (SDL_Gamepad* gamepad : bd->Gamepads)
+        merged_value |= SDL_GetGamepadButton(gamepad, button_no) != 0;
+    io.AddKeyEvent(key, merged_value);
+}
+
+static inline float Saturate(float v) { return v < 0.0f ? 0.0f : v  > 1.0f ? 1.0f : v; }
+static void ImGui_ImplSDL3_UpdateGamepadAnalog(ImGui_ImplSDL3_Data* bd, ImGuiIO& io, ImGuiKey key, SDL_GamepadAxis axis_no, float v0, float v1)
+{
+    float merged_value = 0.0f;
+    for (SDL_Gamepad* gamepad : bd->Gamepads)
+    {
+        float vn = Saturate((float)(SDL_GetGamepadAxis(gamepad, axis_no) - v0) / (float)(v1 - v0));
+        if (merged_value < vn)
+            merged_value = vn;
+    }
+    io.AddKeyAnalogEvent(key, merged_value > 0.1f, merged_value);
+}
+
 static void ImGui_ImplSDL3_UpdateGamepads()
 {
     ImGuiIO& io = ImGui::GetIO();
-    if ((io.ConfigFlags & ImGuiConfigFlags_NavEnableGamepad) == 0) // FIXME: Technically feeding gamepad shouldn't depend on this now that they are regular inputs.
+    ImGui_ImplSDL3_Data* bd = ImGui_ImplSDL3_GetBackendData();
-        return;
 
-    // Get gamepad
+    // Update list of gamepads to use
+    if (bd->WantUpdateGamepadsList && bd->GamepadMode != ImGui_ImplSDL3_GamepadMode_Manual)
+    {
+        ImGui_ImplSDL3_CloseGamepads();
+        int sdl_gamepads_count = 0;
+        SDL_JoystickID* sdl_gamepads = SDL_GetGamepads(&sdl_gamepads_count);
+        for (int n = 0; n < sdl_gamepads_count; n++)
+            if (SDL_Gamepad* gamepad = SDL_OpenGamepad(sdl_gamepads[n]))
+            {
+                bd->Gamepads.push_back(gamepad);
+                if (bd->GamepadMode == ImGui_ImplSDL3_GamepadMode_AutoFirst)
+                    break;
+            }
+        bd->WantUpdateGamepadsList = false;
+    }
+
+    // FIXME: Technically feeding gamepad shouldn't depend on this now that they are regular inputs.
+    if ((io.ConfigFlags & ImGuiConfigFlags_NavEnableGamepad) == 0)
+        return;
     io.BackendFlags &= ~ImGuiBackendFlags_HasGamepad;
-    SDL_Gamepad* gamepad = SDL_OpenGamepad(0);
+    if (bd->Gamepads.Size == 0)
-    if (!gamepad)
         return;
     io.BackendFlags |= ImGuiBackendFlags_HasGamepad;
 
     // Update gamepad inputs
-    #define IM_SATURATE(V)                      (V < 0.0f ? 0.0f : V > 1.0f ? 1.0f : V)
+    const int thumb_dead_zone = 8000;           // SDL_gamepad.h suggests using this value.
-    #define MAP_BUTTON(KEY_NO, BUTTON_NO)       { io.AddKeyEvent(KEY_NO, SDL_GetGamepadButton(gamepad, BUTTON_NO) != 0); }
+    ImGui_ImplSDL3_UpdateGamepadButton(bd, io, ImGuiKey_GamepadStart,           SDL_GAMEPAD_BUTTON_START);
-    #define MAP_ANALOG(KEY_NO, AXIS_NO, V0, V1) { float vn = (float)(SDL_GetGamepadAxis(gamepad, AXIS_NO) - V0) / (float)(V1 - V0); vn = IM_SATURATE(vn); io.AddKeyAnalogEvent(KEY_NO, vn > 0.1f, vn); }
+    ImGui_ImplSDL3_UpdateGamepadButton(bd, io, ImGuiKey_GamepadBack,            SDL_GAMEPAD_BUTTON_BACK);
-    const int thumb_dead_zone = 8000;           // SDL_gamecontroller.h suggests using this value.
+    ImGui_ImplSDL3_UpdateGamepadButton(bd, io, ImGuiKey_GamepadFaceLeft,        SDL_GAMEPAD_BUTTON_WEST);           // Xbox X, PS Square
-    MAP_BUTTON(ImGuiKey_GamepadStart,           SDL_GAMEPAD_BUTTON_START);
+    ImGui_ImplSDL3_UpdateGamepadButton(bd, io, ImGuiKey_GamepadFaceRight,       SDL_GAMEPAD_BUTTON_EAST);           // Xbox B, PS Circle
-    MAP_BUTTON(ImGuiKey_GamepadBack,            SDL_GAMEPAD_BUTTON_BACK);
+    ImGui_ImplSDL3_UpdateGamepadButton(bd, io, ImGuiKey_GamepadFaceUp,          SDL_GAMEPAD_BUTTON_NORTH);          // Xbox Y, PS Triangle
-    MAP_BUTTON(ImGuiKey_GamepadFaceLeft,        SDL_GAMEPAD_BUTTON_WEST);           // Xbox X, PS Square
+    ImGui_ImplSDL3_UpdateGamepadButton(bd, io, ImGuiKey_GamepadFaceDown,        SDL_GAMEPAD_BUTTON_SOUTH);          // Xbox A, PS Cross
-    MAP_BUTTON(ImGuiKey_GamepadFaceRight,       SDL_GAMEPAD_BUTTON_EAST);           // Xbox B, PS Circle
+    ImGui_ImplSDL3_UpdateGamepadButton(bd, io, ImGuiKey_GamepadDpadLeft,        SDL_GAMEPAD_BUTTON_DPAD_LEFT);
-    MAP_BUTTON(ImGuiKey_GamepadFaceUp,          SDL_GAMEPAD_BUTTON_NORTH);          // Xbox Y, PS Triangle
+    ImGui_ImplSDL3_UpdateGamepadButton(bd, io, ImGuiKey_GamepadDpadRight,       SDL_GAMEPAD_BUTTON_DPAD_RIGHT);
-    MAP_BUTTON(ImGuiKey_GamepadFaceDown,        SDL_GAMEPAD_BUTTON_SOUTH);          // Xbox A, PS Cross
+    ImGui_ImplSDL3_UpdateGamepadButton(bd, io, ImGuiKey_GamepadDpadUp,          SDL_GAMEPAD_BUTTON_DPAD_UP);
-    MAP_BUTTON(ImGuiKey_GamepadDpadLeft,        SDL_GAMEPAD_BUTTON_DPAD_LEFT);
+    ImGui_ImplSDL3_UpdateGamepadButton(bd, io, ImGuiKey_GamepadDpadDown,        SDL_GAMEPAD_BUTTON_DPAD_DOWN);
-    MAP_BUTTON(ImGuiKey_GamepadDpadRight,       SDL_GAMEPAD_BUTTON_DPAD_RIGHT);
+    ImGui_ImplSDL3_UpdateGamepadButton(bd, io, ImGuiKey_GamepadL1,              SDL_GAMEPAD_BUTTON_LEFT_SHOULDER);
-    MAP_BUTTON(ImGuiKey_GamepadDpadUp,          SDL_GAMEPAD_BUTTON_DPAD_UP);
+    ImGui_ImplSDL3_UpdateGamepadButton(bd, io, ImGuiKey_GamepadR1,              SDL_GAMEPAD_BUTTON_RIGHT_SHOULDER);
-    MAP_BUTTON(ImGuiKey_GamepadDpadDown,        SDL_GAMEPAD_BUTTON_DPAD_DOWN);
+    ImGui_ImplSDL3_UpdateGamepadAnalog(bd, io, ImGuiKey_GamepadL2,              SDL_GAMEPAD_AXIS_LEFT_TRIGGER,  0.0f, 32767);
-    MAP_BUTTON(ImGuiKey_GamepadL1,              SDL_GAMEPAD_BUTTON_LEFT_SHOULDER);
+    ImGui_ImplSDL3_UpdateGamepadAnalog(bd, io, ImGuiKey_GamepadR2,              SDL_GAMEPAD_AXIS_RIGHT_TRIGGER, 0.0f, 32767);
-    MAP_BUTTON(ImGuiKey_GamepadR1,              SDL_GAMEPAD_BUTTON_RIGHT_SHOULDER);
+    ImGui_ImplSDL3_UpdateGamepadButton(bd, io, ImGuiKey_GamepadL3,              SDL_GAMEPAD_BUTTON_LEFT_STICK);
-    MAP_ANALOG(ImGuiKey_GamepadL2,              SDL_GAMEPAD_AXIS_LEFT_TRIGGER,  0.0f, 32767);
+    ImGui_ImplSDL3_UpdateGamepadButton(bd, io, ImGuiKey_GamepadR3,              SDL_GAMEPAD_BUTTON_RIGHT_STICK);
-    MAP_ANALOG(ImGuiKey_GamepadR2,              SDL_GAMEPAD_AXIS_RIGHT_TRIGGER, 0.0f, 32767);
+    ImGui_ImplSDL3_UpdateGamepadAnalog(bd, io, ImGuiKey_GamepadLStickLeft,      SDL_GAMEPAD_AXIS_LEFTX,  -thumb_dead_zone, -32768);
-    MAP_BUTTON(ImGuiKey_GamepadL3,              SDL_GAMEPAD_BUTTON_LEFT_STICK);
+    ImGui_ImplSDL3_UpdateGamepadAnalog(bd, io, ImGuiKey_GamepadLStickRight,     SDL_GAMEPAD_AXIS_LEFTX,  +thumb_dead_zone, +32767);
-    MAP_BUTTON(ImGuiKey_GamepadR3,              SDL_GAMEPAD_BUTTON_RIGHT_STICK);
+    ImGui_ImplSDL3_UpdateGamepadAnalog(bd, io, ImGuiKey_GamepadLStickUp,        SDL_GAMEPAD_AXIS_LEFTY,  -thumb_dead_zone, -32768);
-    MAP_ANALOG(ImGuiKey_GamepadLStickLeft,      SDL_GAMEPAD_AXIS_LEFTX,  -thumb_dead_zone, -32768);
+    ImGui_ImplSDL3_UpdateGamepadAnalog(bd, io, ImGuiKey_GamepadLStickDown,      SDL_GAMEPAD_AXIS_LEFTY,  +thumb_dead_zone, +32767);
-    MAP_ANALOG(ImGuiKey_GamepadLStickRight,     SDL_GAMEPAD_AXIS_LEFTX,  +thumb_dead_zone, +32767);
+    ImGui_ImplSDL3_UpdateGamepadAnalog(bd, io, ImGuiKey_GamepadRStickLeft,      SDL_GAMEPAD_AXIS_RIGHTX, -thumb_dead_zone, -32768);
-    MAP_ANALOG(ImGuiKey_GamepadLStickUp,        SDL_GAMEPAD_AXIS_LEFTY,  -thumb_dead_zone, -32768);
+    ImGui_ImplSDL3_UpdateGamepadAnalog(bd, io, ImGuiKey_GamepadRStickRight,     SDL_GAMEPAD_AXIS_RIGHTX, +thumb_dead_zone, +32767);
-    MAP_ANALOG(ImGuiKey_GamepadLStickDown,      SDL_GAMEPAD_AXIS_LEFTY,  +thumb_dead_zone, +32767);
+    ImGui_ImplSDL3_UpdateGamepadAnalog(bd, io, ImGuiKey_GamepadRStickUp,        SDL_GAMEPAD_AXIS_RIGHTY, -thumb_dead_zone, -32768);
-    MAP_ANALOG(ImGuiKey_GamepadRStickLeft,      SDL_GAMEPAD_AXIS_RIGHTX, -thumb_dead_zone, -32768);
+    ImGui_ImplSDL3_UpdateGamepadAnalog(bd, io, ImGuiKey_GamepadRStickDown,      SDL_GAMEPAD_AXIS_RIGHTY, +thumb_dead_zone, +32767);
-    MAP_ANALOG(ImGuiKey_GamepadRStickRight,     SDL_GAMEPAD_AXIS_RIGHTX, +thumb_dead_zone, +32767);
-    MAP_ANALOG(ImGuiKey_GamepadRStickUp,        SDL_GAMEPAD_AXIS_RIGHTY, -thumb_dead_zone, -32768);
-    MAP_ANALOG(ImGuiKey_GamepadRStickDown,      SDL_GAMEPAD_AXIS_RIGHTY, +thumb_dead_zone, +32767);
-    #undef MAP_BUTTON
-    #undef MAP_ANALOG
 }
 
 void ImGui_ImplSDL3_NewFrame()

backends/imgui_impl_sdl3.h

@@ -26,6 +26,7 @@
 
 struct SDL_Window;
 struct SDL_Renderer;
+struct SDL_Gamepad;
 typedef union SDL_Event SDL_Event;
 
 IMGUI_IMPL_API bool     ImGui_ImplSDL3_InitForOpenGL(SDL_Window* window, void* sdl_gl_context);
@@ -38,4 +39,9 @@ IMGUI_IMPL_API void     ImGui_ImplSDL3_Shutdown();
 IMGUI_IMPL_API void     ImGui_ImplSDL3_NewFrame();
 IMGUI_IMPL_API bool     ImGui_ImplSDL3_ProcessEvent(const SDL_Event* event);
 
+// Gamepad selection automatically starts in AutoFirst mode, picking first available SDL_Gamepad. You may override this.
+// When using manual mode, caller is responsible for opening/closing gamepad.
+enum ImGui_ImplSDL3_GamepadMode { ImGui_ImplSDL3_GamepadMode_AutoFirst, ImGui_ImplSDL3_GamepadMode_AutoAll, ImGui_ImplSDL3_GamepadMode_Manual };
+IMGUI_IMPL_API void     ImGui_ImplSDL3_SetGamepadMode(ImGui_ImplSDL3_GamepadMode mode, SDL_Gamepad** manual_gamepads_array = NULL, int manual_gamepads_count = -1);
+
 #endif // #ifndef IMGUI_DISABLE

docs/CHANGELOG.txt

@@ -54,7 +54,8 @@ Other changes:
   continuously. Added support for multiple simultaneous gamepads.
   Added ImGui_ImplSDL2_SetGamepadMode()) function to select whether to automatically pick
   first available gamepad, all gamepads, or specific gamepads.
-  (#3884, #6559, #6890) [@ocornut, @lethal-guitar, @wn2000, @bog-dan-ro]
+  (#3884, #6559, #6890, #7180) [@ocornut, @lethal-guitar, @wn2000, @bog-dan-ro]
+- BackendsL SDL3: Fixed gamepad handling. (#7180) [@bog-dan-ro]
 - Backends: SDLRenderer3: query newly added SDL_RenderViewportSet() to not restore
   a wrong viewport if none was initially set.
 - Backends: DirectX9: Using RGBA format when allowed by the driver to avoid CPU side