# Function Reference

# _WinAPI_CallWindowProcW

Passes message information to the specified window procedure

#include <WinAPISysWin.au3>
_WinAPI_CallWindowProcW ( $pPrevWndProc, $hWnd, $iMsg, $wParam, $lParam )

## Parameters

$pPrevWndProc | The address of a previous window procedure, or a special internal value meaningful only to _WinAPI_CallWindowProcW() function.
$hWnd | A handle to the window procedure that received the message.
$iMsg | The message.
$wParam | Additional message-specific information. The content of this parameter depends on the message.
$lParam | Additional message-specific information. The content of this parameter depends on the message.

## Return Value

Returns the result of the message processing and depends on the message sent.

## Remarks

Use this function for window subclassing. Usually, all windows with the same class share one window procedure.
A subclass is a window or set of windows with the same class whose messages are intercepted and processed by another window procedure (or procedures) before being passed to the window procedure of the class.
The _WinAPI_CallWindowProcW() function handles Unicode-to-ANSI conversion.
You cannot take advantage of this conversion if you call the window procedure directly.

## See Also

Search CallWindowProc in MSDN Library.