dlls/ddraw/ddcomimpl.h

   1 /* A few helpful macros for implementing COM objects.
   2  *
   3  * Copyright 2000 TransGaming Technologies Inc.
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2.1 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  18  */
  19
  20 #ifndef _DDCOMIMPL_H_
  21 #define _DDCOMIMPL_H_
  22
  23 #include <stddef.h>
  24
  25 /* Generates the name for a vtable pointer for a given interface. */
  26 /* The canonical name for a single interface is "lpVtbl". */
  27 #define ICOM_VFIELD_MULTI_NAME(iface) iface##_vtbl
  28
  29 /* Returns the offset of a vtable pointer within an implementation object. */
  30 #define ICOM_VFIELD_OFFSET(impltype, iface) \
  31         offsetof(impltype, ICOM_VFIELD_MULTI_NAME(iface))
  32
  33 /* Given an interface pointer, returns the implementation pointer. */
  34 #define ICOM_OBJECT(impltype, ifacename, ifaceptr)              \
  35         (impltype*)((ifaceptr) == NULL ? NULL                   \
  36                   : (char*)(ifaceptr) - ICOM_VFIELD_OFFSET(impltype,ifacename))
  37
  38 #define ICOM_THIS_FROM(impltype, ifacename, ifaceptr) \
  39         impltype* This = ICOM_OBJECT(impltype, ifacename, ifaceptr)
  40
  41 #define COM_INTERFACE_CAST(impltype, ifnamefrom, ifnameto, ifaceptr) \
  42     ((ifaceptr) ? (ifnameto *)&(((impltype *)((char *)(ifaceptr) \
  43     - ICOM_VFIELD_OFFSET(impltype, ifnamefrom)))->ICOM_VFIELD_MULTI_NAME(ifnameto)) : NULL)
  44 #endif /* _DDCOMIMPL_H_ */