A SendAsyncProc function is an application-defined callback function that the operating system calls when the SendMessageCallback function is called. The system passes the message to the callback function after passing the message to the destination window procedure. A value of type SENDASYNCPROC is a pointer to such a function.
VOID CALLBACK SendAsyncProc(
| HWND hwnd, | // handle of destination window |
| UINT uMsg, | // message |
| DWORD dwData, | // application-defined value |
| LRESULT lResult | // result of message processing |
| ); |
Parameters
hwnd
Identifies the window whose window procedure received the message.
If the SendMessageCallback function was called with its hwnd parameter set to HWND_BROADCAST, the operating system calls the SendAsyncProc function once for each top-level window.
uMsg
Specifies the message.
dwData
Specifies an application-defined value sent from the SendMessageCallback function.
lResult
Specifies the result of the message processing and depends on the message.
Return Values
This callback function does not return a value.
Remarks
SendAsyncProc is a placeholder for an application-defined function name.
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.
See Also