CallMsgFilter
The CallMsgFilter
function passes the specified message and hook code to the hook procedures
associated with the WH_SYSMSGFILTER and WH_MSGFILTER hooks. A WH_SYSMSGFILTER or
WH_MSGFILTER hook procedure is an application-defined callback function that
examines and, optionally, modifies messages for a dialog box, message box,
menu, or scroll bar.
BOOL CallMsgFilter(
|
LPMSG lpMsg, |
// pointer to
structure with message data |
|
int nCode |
// hook code |
|
); |
|
Parameters
lpMsg
Pointer to an
MSG
structure that contains the message to be passed to the hook procedures.
nCode
Specifies an
application-defined code used by the hook procedure to determine how to process
the message. The code must not have the same value as system-defined hook codes
(MSGF_ and HC_) associated with the WH_SYSMSGFILTER and WH_MSGFILTER hooks.
Return Values
If the
application should process the message further, the return value is zero.
If the
application should not process the message further, the return value is
nonzero.
Remarks
Windows calls
CallMsgFilter to enable applications to examine and control the flow of
messages during internal processing of dialog boxes, message boxes, menus, and
scroll bars, or when the user activates a different window by pressing the ALT+TAB key
combination.
An
application installs a hook procedure by using the SetWindowsHookEx
function.
See Also