ddraw: Use unsafe_impl_from_IDirect3DViewport2 for application provided interfaces.

dlls/ddraw/ddraw_private.h

@@ -470,6 +470,7 @@ struct IDirect3DViewportImpl
 };
 
 IDirect3DViewportImpl *unsafe_impl_from_IDirect3DViewport3(IDirect3DViewport3 *iface) DECLSPEC_HIDDEN;
+IDirect3DViewportImpl *unsafe_impl_from_IDirect3DViewport2(IDirect3DViewport2 *iface) DECLSPEC_HIDDEN;
 IDirect3DViewportImpl *unsafe_impl_from_IDirect3DViewport(IDirect3DViewport *iface) DECLSPEC_HIDDEN;
 
 /* Helper functions */

dlls/ddraw/device.c

@@ -771,7 +771,7 @@ static HRESULT WINAPI IDirect3DDeviceImpl_2_AddViewport(IDirect3DDevice2 *iface,
         IDirect3DViewport2 *Direct3DViewport2)
 {
     IDirect3DDeviceImpl *This = device_from_device2(iface);
-    IDirect3DViewportImpl *vp = (IDirect3DViewportImpl *)Direct3DViewport2;
+    IDirect3DViewportImpl *vp = unsafe_impl_from_IDirect3DViewport2(Direct3DViewport2);
 
     TRACE("iface %p, viewport %p.\n", iface, Direct3DViewport2);
 
@@ -832,7 +832,7 @@ static HRESULT WINAPI IDirect3DDeviceImpl_2_DeleteViewport(IDirect3DDevice2 *ifa
         IDirect3DViewport2 *Direct3DViewport2)
 {
     IDirect3DDeviceImpl *This = device_from_device2(iface);
-    IDirect3DViewportImpl *vp = (IDirect3DViewportImpl *)Direct3DViewport2;
+    IDirect3DViewportImpl *vp = unsafe_impl_from_IDirect3DViewport2(Direct3DViewport2);
 
     TRACE("iface %p, viewport %p.\n", iface, Direct3DViewport2);
 
@@ -927,7 +927,7 @@ static HRESULT WINAPI IDirect3DDeviceImpl_2_NextViewport(IDirect3DDevice2 *iface
         IDirect3DViewport2 *Viewport2, IDirect3DViewport2 **lplpDirect3DViewport2, DWORD Flags)
 {
     IDirect3DDeviceImpl *This = device_from_device2(iface);
-    IDirect3DViewportImpl *vp = (IDirect3DViewportImpl *)Viewport2;
+    IDirect3DViewportImpl *vp = unsafe_impl_from_IDirect3DViewport2(Viewport2);
     IDirect3DViewport3 *res;
     HRESULT hr;
 
@@ -1749,7 +1749,7 @@ static HRESULT WINAPI IDirect3DDeviceImpl_2_SetCurrentViewport(IDirect3DDevice2
         IDirect3DViewport2 *Direct3DViewport2)
 {
     IDirect3DDeviceImpl *This = device_from_device2(iface);
-    IDirect3DViewportImpl *vp = (IDirect3DViewportImpl *)Direct3DViewport2;
+    IDirect3DViewportImpl *vp = unsafe_impl_from_IDirect3DViewport2(Direct3DViewport2);
 
     TRACE("iface %p, viewport %p.\n", iface, Direct3DViewport2);
 

dlls/ddraw/viewport.c

@@ -1127,6 +1127,14 @@ IDirect3DViewportImpl *unsafe_impl_from_IDirect3DViewport3(IDirect3DViewport3 *i
     return CONTAINING_RECORD(iface, IDirect3DViewportImpl, IDirect3DViewport3_iface);
 }
 
+IDirect3DViewportImpl *unsafe_impl_from_IDirect3DViewport2(IDirect3DViewport2 *iface)
+{
+    /* IDirect3DViewport and IDirect3DViewport3 use the same iface. */
+    if (!iface) return NULL;
+    assert(iface->lpVtbl == (IDirect3DViewport2Vtbl *)&d3d_viewport_vtbl);
+    return CONTAINING_RECORD(iface, IDirect3DViewportImpl, IDirect3DViewport3_iface);
+}
+
 IDirect3DViewportImpl *unsafe_impl_from_IDirect3DViewport(IDirect3DViewport *iface)
 {
     /* IDirect3DViewport and IDirect3DViewport3 use the same iface. */