Data Transfer, COM Enums, and Windows Controls
By Matthew Wilson, November 01, 2003
Transferring information from COM enumerators to windows controls can be complex. Two methods are presented here: a C-API written in C, which sacrifices run-time efficiency for succinct client code and run-time flexibility, and a method using STL sequences and function objects, which is more elegant and also likely to be more efficient.
Data Transfer, COM Enums, and Windows Controls
Listing 1 Definitions of the ListExchange structures and functions
/* /////////////////////////////////////////////////////////////
* ...
*
* Extract from MOCtlFns.h
*
* Copyright (C) 1998-2003, Synesis Software Pty Ltd.
* (Licensed under the Synesis Software Standard Public License:
* http://www.synesis.com.au/licenses/ssspl.html)
*
* ...
* ////////////////////////////////////////////////////////// */
/* Flags */
#define SYLXF_RESETCONTENT (0x00000001) /* Empties control first */
/* Typedefs */
typedef union _Enum2WndItem
{
LPOLESTR olestr; /* OLE string */
BSTR bstr; /* COM BSTR */
VARIANT var; /* COM VARIANT type */
GUID guid; /* GUID */
LPUNKNOWN punk; /* Object */
LPDISPATCH pdisp; /* Automation object */
void *pv; /* any other type */
} Enum2WndItem;
__SyPtrType1(Enum2WndItem)
typedef HRESULT (*PFnEnum_Reset)( LPVOID itf);
typedef HRESULT (*PFnEnum_NextItem)(LPVOID itf,
LPEnum2WndItem item,
LPVOID *pvalue);
typedef void (*PFnEnum_ClearItem)( LPVOID itf,
LPEnum2WndItem item,
LPVOID value);
typedef struct _EnumeratorHandler
{
REFIID iid;
PFnEnum_Reset pfnReset;
PFnEnum_NextItem pfnNextItem;
PFnEnum_ClearItem pfnClearItem;
} EnumeratorHandler;
typedef HRESULT (*PFnCtrl_PutItem)( HWND hwndCtrl,
LPVOID str,
UInt32 flags,
UInt32 param);
typedef void (*PFnCtrl_Reset)( HWND hwndCtrl);
typedef struct _ControlHandler
{
char const *className;
PFnCtrl_PutItem pfnPutItem;
PFnCtrl_Reset pfnReset;
} ControlHandler;
/* Functions */
SInt32 ListExchange_PutItems_Base(HWND hwndList,
LPUNKNOWN punkEnumItems,
UInt32 flags,
UInt32 param,
EnumeratorHandler const *enumerators,
UInt32 cEnumerators,
ControlHandler const *controls,
UInt32 cControls);
SInt32 ListExchange_PutItems( HWND hwndList,
LPUNKNOWN punkEnumItems,
UInt32 flags);
