ddraw: Use unsafe_impl_from_IDirectDrawPalette for application provided interfaces.

dlls/ddraw/ddraw_private.h

@@ -369,6 +369,8 @@ struct IDirectDrawPaletteImpl
     IUnknown                  *ifaceToRelease;
 };
 
+IDirectDrawPaletteImpl *unsafe_impl_from_IDirectDrawPalette(IDirectDrawPalette *iface) DECLSPEC_HIDDEN;
+
 HRESULT ddraw_palette_init(IDirectDrawPaletteImpl *palette,
         IDirectDrawImpl *ddraw, DWORD flags, PALETTEENTRY *entries) DECLSPEC_HIDDEN;
 

dlls/ddraw/palette.c

@@ -258,6 +258,13 @@ static const struct IDirectDrawPaletteVtbl ddraw_palette_vtbl =
     IDirectDrawPaletteImpl_SetEntries
 };
 
+IDirectDrawPaletteImpl *unsafe_impl_from_IDirectDrawPalette(IDirectDrawPalette *iface)
+{
+    if (!iface) return NULL;
+    assert(iface->lpVtbl == &ddraw_palette_vtbl);
+    return CONTAINING_RECORD(iface, IDirectDrawPaletteImpl, lpVtbl);
+}
+
 HRESULT ddraw_palette_init(IDirectDrawPaletteImpl *palette,
         IDirectDrawImpl *ddraw, DWORD flags, PALETTEENTRY *entries)
 {

dlls/ddraw/surface.c

@@ -4288,7 +4288,7 @@ static HRESULT WINAPI ddraw_surface7_SetPalette(IDirectDrawSurface7 *iface, IDir
     IDirectDrawSurfaceImpl *This = impl_from_IDirectDrawSurface7(iface);
     IDirectDrawPalette *oldPal;
     IDirectDrawSurfaceImpl *surf;
-    IDirectDrawPaletteImpl *PalImpl = (IDirectDrawPaletteImpl *)Pal;
+    IDirectDrawPaletteImpl *PalImpl = unsafe_impl_from_IDirectDrawPalette(Pal);
     HRESULT hr;
 
     TRACE("iface %p, palette %p.\n", iface, Pal);