ddraw: Use unsafe_impl_from_IDirectDrawSurface4.

dlls/ddraw/ddraw.c

@@ -4243,7 +4243,7 @@ static HRESULT WINAPI ddraw4_DuplicateSurface(IDirectDraw4 *iface, IDirectDrawSu
         IDirectDrawSurface4 **dst)
 {
     IDirectDrawImpl *This = impl_from_IDirectDraw4(iface);
-    IDirectDrawSurfaceImpl *src_impl = (IDirectDrawSurfaceImpl *)src;
+    IDirectDrawSurfaceImpl *src_impl = unsafe_impl_from_IDirectDrawSurface4(src);
     IDirectDrawSurface7 *dst7;
     IDirectDrawSurfaceImpl *dst_impl;
     HRESULT hr;
@@ -4879,7 +4879,7 @@ static HRESULT WINAPI d3d3_CreateDevice(IDirect3D3 *iface, REFCLSID riid,
         IDirectDrawSurface4 *surface, IDirect3DDevice3 **device, IUnknown *outer_unknown)
 {
     IDirectDrawImpl *This = impl_from_IDirect3D3(iface);
-    IDirectDrawSurfaceImpl *surface_impl = (IDirectDrawSurfaceImpl *)surface;
+    IDirectDrawSurfaceImpl *surface_impl = unsafe_impl_from_IDirectDrawSurface4(surface);
     HRESULT hr;
 
     TRACE("iface %p, riid %s, surface %p, device %p, outer_unknown %p.\n",

dlls/ddraw/ddraw_private.h

@@ -231,6 +231,7 @@ static inline IDirectDrawSurfaceImpl *impl_from_IDirectDrawSurface7(IDirectDrawS
 }
 
 IDirectDrawSurfaceImpl *unsafe_impl_from_IDirectDrawSurface3(IDirectDrawSurface3 *iface) DECLSPEC_HIDDEN;
+IDirectDrawSurfaceImpl *unsafe_impl_from_IDirectDrawSurface4(IDirectDrawSurface4 *iface) DECLSPEC_HIDDEN;
 IDirectDrawSurfaceImpl *unsafe_impl_from_IDirectDrawSurface7(IDirectDrawSurface7 *iface) DECLSPEC_HIDDEN;
 
 /* Get the number of bytes per pixel for a given surface */

dlls/ddraw/device.c

@@ -1889,7 +1889,7 @@ static HRESULT WINAPI IDirect3DDeviceImpl_3_SetRenderTarget(IDirect3DDevice3 *if
         IDirectDrawSurface4 *NewRenderTarget, DWORD Flags)
 {
     IDirect3DDeviceImpl *This = device_from_device3(iface);
-    IDirectDrawSurfaceImpl *Target = (IDirectDrawSurfaceImpl *)NewRenderTarget;
+    IDirectDrawSurfaceImpl *Target = unsafe_impl_from_IDirectDrawSurface4(NewRenderTarget);
 
     TRACE("iface %p, target %p, flags %#x.\n", iface, NewRenderTarget, Flags);
 

dlls/ddraw/surface.c

@@ -3465,6 +3465,13 @@ IDirectDrawSurfaceImpl *unsafe_impl_from_IDirectDrawSurface7(IDirectDrawSurface7
     return CONTAINING_RECORD(iface, IDirectDrawSurfaceImpl, IDirectDrawSurface7_iface);
 }
 
+IDirectDrawSurfaceImpl *unsafe_impl_from_IDirectDrawSurface4(IDirectDrawSurface4 *iface)
+{
+    if (!iface) return NULL;
+    assert(iface->lpVtbl == (struct IDirectDrawSurface4Vtbl *)&ddraw_surface7_vtbl);
+    return CONTAINING_RECORD(iface, IDirectDrawSurfaceImpl, IDirectDrawSurface7_iface);
+}
+
 IDirectDrawSurfaceImpl *unsafe_impl_from_IDirectDrawSurface3(IDirectDrawSurface3 *iface)
 {
     if (!iface) return NULL;