MouseProc 4H.B.NP

The MouseProc hook procedure is an application-defined or library-defined callback function the system calls whenever an application calls the GetMessage or PeekMessage0X9XXX function and there is a mouse message to be processed.

LRESULT CALLBACK MouseProc(

int nCode,	// hook code
WPARAM wParam,	// message identifier
LPARAM lParam	// mouse coordinates
);

Parameters

nCode

Specifies a code the hook procedure uses to determine how to process the message. This parameter can be one of the following values:

Value	Meaning
HC_ACTION	The wParam and lParam parameters contain information about a mouse message.
HC_NOREMOVE	The wParam and lParam parameters contain information about a mouse message, and the mouse message has not been removed from the message queue. (An application called the PeekMessage function, specifying the PM_NOREMOVE flag.)

If nCode is less than zero, the hook procedure must pass the message to the CallNextHookEx2EBDBC function without further processing and should return the value returned by CallNextHookEx.

wParam

Specifies the identifier of the mouse message.

lParam

Points to a MOUSEHOOKSTRUCT13C74VJ structure.

Return Values

To enable the system to process the message, the return value must be zero. To discard the message, the return value must be a nonzero value.

Remarks

The hook procedure must not install a JournalPlaybackProcLESNKT callback function.

An application installs the hook procedure by specifying the WH_MOUSE hook type and the address of the hook procedure in a call to the SetWindowsHookEx function.

MouseProc is a placeholder for the application-defined or library-defined function name.