[PATCH 0/1] MR7088: win32u: Use a color table with default palette for 8bpp window surfaces.

[Rémi Bernon (＠rbernon)]

NtGdiCreateDIBSection will allocate a color table for 8bpp bitmap anyway
and if biClrUsed isn't set, we will later fail any color lookup.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=57584

[PATCH 1/1] win32u: Use a color table with default palette for 8bpp window surfaces.

[Rémi Bernon]

From: Rémi Bernon

NtGdiCreateDIBSection will allocate a color table for 8bpp bitmap anyway
and if biClrUsed isn't set, we will later fail any color lookup.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=57584
---
 dlls/win32u/dce.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/dlls/win32u/dce.c b/dlls/win32u/dce.c
index d9c5f161385..23e67e3623e 100644
--- a/dlls/win32u/dce.c
+++ b/dlls/win32u/dce.c
@@ -526,6 +526,7 @@ static BOOL update_surface_shape( struct window_surface *surface, const RECT *re
 W32KAPI struct window_surface *window_surface_create( UINT size, const struct window_surface_funcs *funcs, HWND hwnd,
                                                       const RECT *rect, BITMAPINFO *info, HBITMAP bitmap )
 {
+    UINT usage = info->bmiHeader.biBitCount <= 8 ? DIB_PAL_COLORS : DIB_RGB_COLORS;
     struct window_surface *surface;

if (!(surface = calloc( 1, size ))) return NULL;
@@ -538,7 +539,8 @@ W32KAPI struct window_surface *window_surface_create( UINT size, const struct wi
     surface->alpha_mask = 0;
     reset_bounds( &surface->bounds );

-    if (!bitmap) bitmap = NtGdiCreateDIBSection( 0, NULL, 0, info, DIB_RGB_COLORS, 0, 0, 0, NULL );
+    if (usage == DIB_PAL_COLORS) info->bmiHeader.biClrUsed = 1 << info->bmiHeader.biBitCount;
+    if (!bitmap) bitmap = NtGdiCreateDIBSection( 0, NULL, 0, info, usage, 0, 0, 0, NULL );
     if (!(surface->color_bitmap = bitmap))
     {
         free( surface );

[Rémi Bernon (＠rbernon)]

Is there something wrong here? This is a very small corner case that's only used on X11 when host display is 8bpp or less. In addition, looking at the code I don't think creating a 8bpp bitmap without a color table is valid.

[Alexandre Julliard (＠julliard)]

I don't see how DIB_PAL_COLORS can possibly work without a DC, and either way the caller needs to provide a BITMAPINFO with a valid color table.

[Rémi Bernon (＠rbernon)]

Hmm right, I see... it possibly fixed the issue because the surface creation failed, sorry.