WinSetMsgInterest

This function sets a window's message interest.

Syntax

WinSetMsgInterest(hwnd, ulMsgClass, lControl)

Parameters

hwnd (HWND) - Input

Window handle.

ulMsgClass (ULONG) - Input

Message class to set interest for. Can be a specific message ID (e.g., WM_SHOW) or SMIM_ALL (all messages except WM_QUIT under certain lControl values).

lControl (LONG) - Input

Interest identifier.

SMI_RESET: Revert to the interest specified for the window class.
SMI_INTEREST: Interested in the messages.
SMI_NOINTEREST: Not interested in the messages.
SMI_AUTODISPATCH: Interested, but messages should be automatically dispatched to the window procedure.

rc (BOOL) - Returns: TRUE if interest was successfully changed, FALSE otherwise.

Returns

rc (BOOL) - returns

Interest-changed indicator.

TRUE: Interest successfully changed
FALSE: Interest not successfully changed.

Remarks

This function only works if the MsgControlHook hook has been set.

The interest for WM_QUIT cannot be set to SMI_AUTODISPATCH using SMIM_ALL, as WM_QUIT is the standard way to terminate an application. It can be set specifically if needed.

Errors

Possible returns from WinGetLastError:

PMERR_INVALID_HWND (0x1001) - An invalid window handle was specified.

Example Code

#define INCL_WINMESSAGEMGR /* Or use INCL_WIN, INCL_PM, */
#include <os2.h>

HWND    hwnd;       /* Window handle. */
ULONG   ulMsgClass; /* Message class to have interest level set. */
LONG    lControl;   /* Interest-identifier for the message class. */
BOOL    rc;         /* Interest-changed indicator. */

rc = WinSetMsgInterest(hwnd, ulMsgClass, lControl);

This example sets the message interest of a window to only WM_SHOW messages.

#define INCL_WINMESSAGEMGR
#define INCL_WINHOOKS
#include <OS2.H>

HWND hwnd;
HAB  hab;
BOOL fSuccess;
  /* Hook Procedure Prototype */

BOOL MsgCtlHook(HAB hab,LONG  idContext,     /* this hook can */
           HWND hwnd, PSZ pszClassname,      /* be given any */
           ULONG  ulMsgclass,                /* name.           */
           LONG  idControl, PBOOL fSuccess);

main()
{
/* This function passes the hook procedure address to the system. */

WinSetHook(hab,
          (HMQ)0,
          MCHK_CLASSMSGINTEREST,
          (PFN)MsgCtlHook,
          (HMODULE)0); /* hook is into application queue. */

 /* This function sets the message interest of a window class. */
     WinSetMsgInterest(hwnd,
                       WM_SHOW,
                       SMI_AUTODISPATCH); /* interested in the */
                                  /* messages, but they are to      */
                                  /* be automatically dispatched      */
                                  /* to the window procedure.        */
}

BOOL MsgCtlHook(HAB hab, LONG idContext,         /* this hook can */
           HWND hwnd, PSZ pszClassname,      /* be given any  */
           ULONG ulMsgclass,                /* name.           */
           LONG idControl, PBOOL fSuccess)
{
/* ... */
}

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