JournalRecordProc

3.1

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

Parameters

code

Specifies whether the callback function should process the message or call the CallNextHookEx function. If this parameter is less than zero, the callback function should pass the message to CallNextHookEx without further processing.

wParam

Specifies a NULL value.

lParam

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

typedef struct tagMSG {     /* msg */
    HWND   hwnd;
    UINT   message;
    WPARAM wParam;
    LPARAM lParam;
    DWORD  time;
    POINT  pt;
} MSG;

For a full description of this structure, see the Microsoft Windows Programmer's Reference, Volume 3.

Return Value

The 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.

This callback function must be in a dynamic-link library.

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

JournalRecordProc is a placeholder for the library-defined function name. The actual name must be exported by including it in an EXPORTS statement in the library's module-definition file.

See Also

CallNextHookEx, JournalPlaybackProc, SetWindowsHookEx