From a96664674f6174773ef4a30eb1c53afcdddcaae1 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Sun, 9 Nov 2025 07:42:50 -0800
Subject: [PATCH] Fixed windows events on 32-bit Windows
When running on 32-bit Windows, DefWindowProc resolves to a function in ntdll.dll, but after the window is created the actual window proc is a function in user32.dll. We solve this by using our own custom default window proc and looking for that instead.
Fixes https://github.com/libsdl-org/SDL/issues/1442
---
src/video/windows/SDL_windowsevents.c | 7 ++++++-
src/video/windows/SDL_windowsevents.h | 4 ++--
src/video/windows/SDL_windowswindow.c | 4 ++--
3 files changed, 10 insertions(+), 5 deletions(-)
diff --git a/src/video/windows/SDL_windowsevents.c b/src/video/windows/SDL_windowsevents.c
index bde2a53bdeebd..b9f6e9dba0813 100644
--- a/src/video/windows/SDL_windowsevents.c
+++ b/src/video/windows/SDL_windowsevents.c
@@ -2471,6 +2471,11 @@ LRESULT CALLBACK WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lPara
}
}
+LRESULT CALLBACK WIN_DefWindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
+{
+ return CallWindowProc(DefWindowProc, hwnd, msg, wParam, lParam);
+}
+
int WIN_WaitEventTimeout(SDL_VideoDevice *_this, Sint64 timeoutNS)
{
if (g_WindowsEnableMessageLoop) {
@@ -2754,7 +2759,7 @@ bool SDL_RegisterApp(const char *name, Uint32 style, void *hInst)
wcex.cbSize = sizeof(WNDCLASSEX);
wcex.lpszClassName = SDL_Appname;
wcex.style = SDL_Appstyle;
- wcex.lpfnWndProc = DefWindowProc;
+ wcex.lpfnWndProc = WIN_DefWindowProc;
wcex.hInstance = SDL_Instance;
#if !defined(SDL_PLATFORM_XBOXONE) && !defined(SDL_PLATFORM_XBOXSERIES)
diff --git a/src/video/windows/SDL_windowsevents.h b/src/video/windows/SDL_windowsevents.h
index 5336013b65ae9..78a92208312e2 100644
--- a/src/video/windows/SDL_windowsevents.h
+++ b/src/video/windows/SDL_windowsevents.h
@@ -28,8 +28,8 @@ extern Uint32 SDL_Appstyle;
extern HINSTANCE SDL_Instance;
extern LRESULT CALLBACK WIN_KeyboardHookProc(int nCode, WPARAM wParam, LPARAM lParam);
-extern LRESULT CALLBACK WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam,
- LPARAM lParam);
+extern LRESULT CALLBACK WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam);
+extern LRESULT CALLBACK WIN_DefWindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam);
extern void WIN_PollRawInput(SDL_VideoDevice *_this, Uint64 poll_start);
extern void WIN_CheckKeyboardAndMouseHotplug(SDL_VideoDevice *_this, bool initial_check);
extern void WIN_PumpEvents(SDL_VideoDevice *_this);
diff --git a/src/video/windows/SDL_windowswindow.c b/src/video/windows/SDL_windowswindow.c
index 223020d2c66a9..542c29f510156 100644
--- a/src/video/windows/SDL_windowswindow.c
+++ b/src/video/windows/SDL_windowswindow.c
@@ -427,13 +427,13 @@ static bool SetupWindowData(SDL_VideoDevice *_this, SDL_Window *window, HWND hwn
// Set up the window proc function
#ifdef GWLP_WNDPROC
data->wndproc = (WNDPROC)GetWindowLongPtr(hwnd, GWLP_WNDPROC);
- if (data->wndproc == DefWindowProc) {
+ if (data->wndproc == WIN_DefWindowProc) {
data->wndproc = NULL;
SetWindowLongPtr(hwnd, GWLP_WNDPROC, (LONG_PTR)WIN_WindowProc);
}
#else
data->wndproc = (WNDPROC)GetWindowLong(hwnd, GWL_WNDPROC);
- if (data->wndproc == DefWindowProc) {
+ if (data->wndproc == WIN_DefWindowProc) {
data->wndproc = NULL;
SetWindowLong(hwnd, GWL_WNDPROC, (LONG_PTR)WIN_WindowProc);
}