Rémi Bernon : win32u: Use the dummy surface for empty layered window surfaces.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 34b1606019982b71818780bc84b76460f650af31
URL:    https://gitlab.winehq.org/wine/wine/-/commit/34b1606019982b71818780bc84b7646...

Author: Rémi Bernon 
Date:   Thu Jul 11 16:43:29 2024 +0200

win32u: Use the dummy surface for empty layered window surfaces.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=56958

---

dlls/win32u/window.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/dlls/win32u/window.c b/dlls/win32u/window.c
index 3fa97d9a107..532d8e7a789 100644
--- a/dlls/win32u/window.c
+++ b/dlls/win32u/window.c
@@ -2228,9 +2228,10 @@ BOOL WINAPI NtUserUpdateLayeredWindow( HWND hwnd, HDC hdc_dst, const POINT *pts_
     if (surface) window_surface_release( surface );

if (!(flags & ULW_COLORKEY)) key = CLR_INVALID;
-    if (!(user_driver->pCreateLayeredWindow( hwnd, &surface_rect, key, &surface )) || !surface) return FALSE;
+    if (IsRectEmpty( &surface_rect )) window_surface_add_ref( (surface = &dummy_surface) );
+    else if (!(user_driver->pCreateLayeredWindow( hwnd, &surface_rect, key, &surface )) || !surface) return FALSE;

-    if (!hdc_src) ret = TRUE;
+    if (!hdc_src || surface == &dummy_surface) ret = TRUE;
     else
     {
         BLENDFUNCTION src_blend = { AC_SRC_OVER, 0, 255, 0 };