Note
Access to this page requires authorization. You can try signing in or changing directories.
Access to this page requires authorization. You can try changing directories.
An application-defined callback function used with the SendMessageCallback function. The system passes the message to the callback function after passing the message to the destination window procedure. The SENDASYNCPROC type defines a pointer to this callback function. SendAsyncProc is a placeholder for the application-defined function name.
Syntax
SENDASYNCPROC Sendasyncproc;
VOID Sendasyncproc(
HWND unnamedParam1,
UINT unnamedParam2,
ULONG_PTR unnamedParam3,
LRESULT unnamedParam4
)
{...}
Parameters
unnamedParam1
Type: HWND
A handle to the window whose window procedure received the message. This parameter is typically named hWnd.
If the SendMessageCallback function was called with its hWnd parameter set to HWND_BROADCAST, the system calls the SendAsyncProc function once for each top-level window.
unnamedParam2
Type: UINT
The message. This parameter is typically named uMsg.
unnamedParam3
Type: ULONG_PTR
An application-defined value sent from the SendMessageCallback function. This parameter is typically named dwData.
unnamedParam4
Type: LRESULT
The result of the message processing. This value depends on the message. This parameter is typically named lResult.
Return value
None
Remarks
Note
The parameters are defined in the header with no names: typedef VOID (CALLBACK* SENDASYNCPROC)(HWND, UINT, ULONG_PTR, LRESULT);. Therefore, the syntax block lists them as unnamedParam1 - unnamedParam4. You can name these parameters anything in your app. However, they are usually named as shown in the parameter descriptions.
You install a SendAsyncProc application-defined callback function by passing a SENDASYNCPROC pointer to the SendMessageCallback function.
The callback function is only called when the thread that called SendMessageCallback calls GetMessage, PeekMessage, or WaitMessage.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows 2000 Professional [desktop apps only] |
| Minimum supported server | Windows 2000 Server [desktop apps only] |
| Target Platform | Windows |
| Header | winuser.h (include Windows.h) |
See also
Conceptual
Reference