The SendNotifyMessage function sends the specified message to a window. If the window was created by the calling thread, SendNotifyMessage calls the window procedure for the window and does not return until the window procedure has processed the message. If the window was created by a different thread, SendNotifyMessage passes the message to the window procedure and returns immediately; it does not wait for the window procedure to finish processing the message.
BOOL SendNotifyMessage(
| HWND hWnd, | // handle of destination window |
| UINT Msg, | // message to send |
| WPARAM wParam, | // first message parameter |
| LPARAM lParam | // second message parameter |
| ); |
Parameters
hWnd
Identifies the window whose window procedure will receive the message. If this parameter is HWND_BROADCAST, the message is sent to all top-level windows in the system, including disabled or invisible unowned windows, overlapped windows, and pop-up windows; but the message is not sent to child windows.
Msg
Specifies the message to be sent.
wParam
Specifies additional message-specific information.
lParam
Specifies additional message-specific information.
Return Values
If the function succeeds, the return value is nonzero.
If the function fails, the return value is zero. To get extended error information, call GetLastError.
Remarks
If you send a message in the range below WM_USER to the asynchronous message functions (PostMessage, SendNotifyMessage, and SendMessageCallback), make sure that the message parameters do not include pointers. Otherwise, the functions will return before the receiving thread has had a chance to process the message and the sender will free the memory before it is used.
Applications that need to communicate using HWND_BROADCAST should use the RegisterWindowMessage function to obtain a unique message for inter-application communication.
See Also
PostMessage, PostThreadMessage, RegisterWindowMessage, SendMessage SendMessageCallback, SendNotifyMessage