JournalRecordProc

LRESULT CALLBACK JournalRecordProc(nCode, wParam, lParam)
int nCode;	/* hook code	*/
WPARAM wParam;	/* undefined	*/
LPARAM lParam;	/* address of message being processed	*/

The JournalRecordProc function is an application- or library-defined callback function that records messages that the system removes from the system message queue. Later, an application or library can use a JournalPlaybackProc function to play back the messages.

Parameters

nCode

Value

Meaning

HC_ACTION
	Indicates that the lParam parameter points to a valid EVENTMSG structure. The filter function should record the event message.
HC_SYSMODALOFF
	Indicates a system-modal dialog box has been destroyed.
HC_SYSMODALON
	Indicates a system-modal dialog box is being displayed. The filter function should unhook itself until the dialog box has been destroyed.

If the nCode parameter is less then zero, the callback function should pass the message to CallNextHookEx without further processing.

wParam

Specifies a NULL value.

lParam

Points to an EVENTMSG structure. The EVENTMSG structure has the following form:

typedef struct tagEVENTMSG { /* em */

UINT message;

UINT paramL;

UINT paramH;

DWORD time;

} EVENTMSG;

Return Value

This callback function should return zero.

Comments

A JournalRecordProc callback function should copy but not modify the messages. After control returns to the system, the message continues to be processed. The callback function does not require a return value.

An application must install the callback function by specifying the WH_JOURNALRECORD filter type and address of the callback function in a call to the SetWindowsHookEx function.

JournalRecordProc is a placeholder for the application- or library-supplied function name. The actual name must be exported by including it in the EXPORTS statement in a module-definition file.