From 699bef1316f9b44572489537a1c869e9dbbd0268 Mon Sep 17 00:00:00 2001
From: Ritchie Swann <ritchieswann@gmail.com>
Date: Sun, 11 Aug 2024 10:33:10 +0100
Subject: [PATCH] Better solution for DwmDefWindowProc on mingw64

On mingw, create our own thunk for DwmDefWindowProc. It should exist in libdwmapi.a (and exists in MSVC), but doesn't.
---
 libraries/ZWidget/CMakeLists.txt              |  3 +++
 .../ZWidget/src/window/win32/win32window.cpp  | 25 ++++++++++++++++---
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/libraries/ZWidget/CMakeLists.txt b/libraries/ZWidget/CMakeLists.txt
index dd836cd6de..68c048e22e 100644
--- a/libraries/ZWidget/CMakeLists.txt
+++ b/libraries/ZWidget/CMakeLists.txt
@@ -120,6 +120,9 @@ include_directories(include include/zwidget src)
 if(WIN32)
 	set(ZWIDGET_SOURCES ${ZWIDGET_SOURCES} ${ZWIDGET_WIN32_SOURCES})
 	add_definitions(-DUNICODE -D_UNICODE)
+	if(MINGW)
+		add_definitions(-DMINGW)
+	endif()
 elseif(APPLE)
 	set(ZWIDGET_SOURCES ${ZWIDGET_SOURCES} ${ZWIDGET_COCOA_SOURCES})
 	set(ZWIDGET_LIBS ${CMAKE_DL_LIBS} -ldl)
diff --git a/libraries/ZWidget/src/window/win32/win32window.cpp b/libraries/ZWidget/src/window/win32/win32window.cpp
index 54350513d6..958c3fef60 100644
--- a/libraries/ZWidget/src/window/win32/win32window.cpp
+++ b/libraries/ZWidget/src/window/win32/win32window.cpp
@@ -29,6 +29,26 @@
 #define RIDEV_INPUTSINK	(0x100)
 #endif
 
+#ifdef MINGW
+// MinGW's library doesn't contain a thunk for DwmDefWindowProc, so we need to create our own
+
+BOOL DwmDefWindowProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam, LRESULT *plResult )
+{
+	typedef LRESULT(* dwmdwp)(HWND, UINT, WPARAM, LPARAM );
+	BOOL result(false);
+	HMODULE module = LoadLibrary( _T( "dwmapi.dll" ) );
+	if( module ) {
+		dwmdwp proc = reinterpret_cast<dwmdwp>( GetProcAddress( module, "DwmDefWindowProc" ) );
+		if( proc ) {
+			*plResult = proc( hWnd, msg, wParam, lParam );
+		}
+		FreeLibrary(module);
+	}
+	return result;
+}
+
+#endif
+
 static std::string from_utf16(const std::wstring& str)
 {
 	if (str.empty()) return {};
@@ -389,9 +409,8 @@ LRESULT Win32Window::OnWindowMessage(UINT msg, WPARAM wparam, LPARAM lparam)
 {
 	LPARAM result = 0;
 
-	// DwmDefWindowProc is not a publicly defined symbol on Windows 11
-	/*if (DwmDefWindowProc(WindowHandle, msg, wparam, lparam, &result))
-		return result;*/
+	if (DwmDefWindowProc(WindowHandle, msg, wparam, lparam, &result))
+		return result;
 
 	if (msg == WM_INPUT)
 	{