DispatchMessage function
Syntax
LRESULT DispatchMessage(
const MSG *lpmsg
);
Parameters
| lpmsg | Pointer to an MSG structure that contains the message to be dispatched. |
|---|
Return value
Returns the value returned by the window procedure that processes the message. If an error occurs, the return value is zero. Call GetLastError for extended error information.
Remarks
The DispatchMessage function sends a message to a window procedure. It is typically called after retrieving a message with GetMessage or PeekMessage. The function does not perform any checks on the validity of the message; the caller must ensure that the message is appropriate for dispatch.
- The message is sent to the window procedure associated with the window handle specified in
lpmsg->hwnd. - If the
hwndmember isNULL, the message is posted to the thread's message queue and dispatched to the thread's message hook procedures. - Sending messages that cause re-entrancy can lead to deadlocks. Use
SendMessageorPostMessageappropriately.
Example
// Simple message loop using DispatchMessage
MSG msg;
while (GetMessage(&msg, NULL, 0, 0)) {
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return (int)msg.wParam;
// Window procedure
LRESULT CALLBACK WndProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {
switch (uMsg) {
case WM_DESTROY:
PostQuitMessage(0);
return 0;
// handle other messages...
default:
return DefWindowProc(hwnd, uMsg, wParam, lParam);
}
}