SetFocus
The SetFocus
function sets the keyboard focus to the specified window. The window must be
associated with the calling thread s message queue.
HWND SetFocus(
|
HWND hWnd |
// handle of window
to receive focus |
|
); |
|
Parameters
hWnd
Identifies
the window that will receive the keyboard input. If this parameter is NULL,
keystrokes are ignored.
Return Values
If the
function succeeds, the return value is the handle of the window that previously
had the keyboard focus. If the hWnd parameter is invalid or the window
is not associated with the calling thread s message queue, the return value is
NULL.
Remarks
The SetFocus
function sends a WM_KILLFOCUS message to the window that loses the keyboard
focus and a WM_SETFOCUS message to the window that receives the keyboard focus.
It also activates either the window that receives the focus or the parent of
the window that receives the focus.
If a window
is active but does not have the focus, any key pressed will produce the
WM_SYSCHAR, WM_SYSKEYDOWN, or WM_SYSKEYUP message. If the VK_MENU key is also
pressed, the lParam parameter of the message will have bit 30 set.
Otherwise, the messages produced do not have this bit set.
By using the AttachThreadInput
function, a thread can attach its input processing to another thread. This
allows a thread to call SetFocus to set the keyboard focus to a window
associated with another thread s message queue.
See Also