Backends: Win32: use XInput Packet to avoid resubmitting gamepad data. (#9202, #8556)

backends/imgui_impl_win32.cpp

diff --git a/backends/imgui_impl_win32.cpp b/backends/imgui_impl_win32.cpp
index c344a14..de92040 100644
--- a/backends/imgui_impl_win32.cpp
+++ b/backends/imgui_impl_win32.cpp
@@ -21,6 +21,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2026-01-28: Inputs: Minor optimization not submitting gamepad input if packet number has not changed (reworked from 2025-09-23 attempt). (#9202, #8556)
 //  2025-12-03: Inputs: handle WM_IME_CHAR/WM_IME_COMPOSITION messages to support Unicode inputs on MBCS (non-Unicode) Windows. (#9099, #3653, #5961)
 //  2025-10-19: Inputs: Revert previous change to allow for io.ClearInputKeys() on focus-out not losing gamepad state.
 //  2025-09-23: Inputs: Minor optimization not submitting gamepad input if packet number has not changed.
@@ -127,6 +128,7 @@
     HMODULE                     XInputDLL;
     PFN_XInputGetCapabilities   XInputGetCapabilities;
     PFN_XInputGetState          XInputGetState;
+    DWORD                       XInputPacketNumber;
 #endif
 
     ImGui_ImplWin32_Data()      { memset((void*)this, 0, sizeof(*this)); }
@@ -358,6 +360,9 @@
     if (!bd->HasGamepad || bd->XInputGetState == nullptr || bd->XInputGetState(0, &xinput_state) != ERROR_SUCCESS)
         return;
     io.BackendFlags |= ImGuiBackendFlags_HasGamepad;
+    if (bd->XInputPacketNumber != 0 && bd->XInputPacketNumber == xinput_state.dwPacketNumber)
+        return;
+    bd->XInputPacketNumber = xinput_state.dwPacketNumber;
 
     #define IM_SATURATE(V)                      (V < 0.0f ? 0.0f : V > 1.0f ? 1.0f : V)
     #define MAP_BUTTON(KEY_NO, BUTTON_ENUM)     { io.AddKeyEvent(KEY_NO, (gamepad.wButtons & BUTTON_ENUM) != 0); }
@@ -771,6 +776,9 @@
     case WM_SETFOCUS:
     case WM_KILLFOCUS:
         io.AddFocusEvent(msg == WM_SETFOCUS);
+#ifndef IMGUI_IMPL_WIN32_DISABLE_GAMEPAD
+        bd->XInputPacketNumber = 0; // FIXME: Technically, calling io.ClearInputKeys() directly would require this as well.
+#endif
         return 0;
     case WM_INPUTLANGCHANGE:
         ImGui_ImplWin32_UpdateKeyboardCodePage(io);

docs/CHANGELOG.txt

diff --git a/docs/CHANGELOG.txt b/docs/CHANGELOG.txt
index 1207595..80bd16b 100644
--- a/docs/CHANGELOG.txt
+++ b/docs/CHANGELOG.txt
@@ -229,6 +229,8 @@
      devices. (#8784) [@FelixStach]
   - Win32: handle `WM_IME_CHAR`/`WM_IME_COMPOSITION` to support Unicode inputs on
     MBCS (non-Unicode) Windows. (#9099, #3653, #5961) [@ulhc, @ocornut, @Othereum]
+  - Win32: minor optimization not submitting gamepad input if packet number has not
+    changed (reworked previous 1.92.4). (#9202, #8556) [@AhmedSamyMousa, @MidTerm-CN]
 - Examples:
    - Win32+DirectX12: ignore seemingly incorrect `D3D12_MESSAGE_ID_FENCE_ZERO_WAIT`
      warning on startups on some setups. (#9084, #9093) [@RT2Code, @LeoGautheron]