CallWndRetProc

[Now Supported on Windows NT]

The CallWndRetProc hook procedure is an application-defined or library-defined callback function the system calls after the SendMessage function is called. After passing the message to the destination window procedure, the system passes the message to the hook procedure. The hook procedure can examine the message; it cannot modify it.

LRESULT CALLBACK CallWndRetProc(

int nCode,	// hook code
WPARAM wParam,	// current-process flag
LPARAM lParam	// address of structure with message data
);

Parameters

nCode

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

wParam

Specifies whether the message is sent by the current process. If the message is sent by the current process, it is nonzero; otherwise, it is NULL.

lParam

Points to a CWPRETSTRUCT structure that contains details about the message.

Return Values

The return value should be zero.

Remarks

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

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

See Also

CallNextHookEx, CallWndProc, CWPRETSTRUCT, SendMessage, SetWindowsHookEx

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