Visual C++ and MFC Programming 2nd Edition

Visual C++ and MFC Fundamentals Chapter 15: Fundamental Controls

BOOL ShowWindow(int nCmdShow);

This method is used to display or hide any window that is a descendent of CWnd. Its

argument, nCmdShow, specifies what to do with the appearance or disappearance of the

object. Its possible values are:

Value Description

SW_SHOW Displays a window and makes it visible

SW_SHOWNORMAL Displays the window in its regular size. In most

circumstances, the operating system keeps track of the

last location and size a window such as Internet

Explorer or My Computer had the last time it was

displaying. This value allows the OS to restore it

SW_SHOWMINIMIZED Opens the window in its minimized state, representing

it as a button on the taskbar

SW_SHOWMAXIMIZED Opens the window in its maximized state

SW_SHOWMINNOACTIVE Opens the window but displays only its icon. It does

not make it active

SW_SHOWNA As previous

SW_SHOWNOACTIVATE Retrieves the window's previous size and location and

displays it accordingly

SW_HIDE Used to hide a window

SW_MINIMIZE shrinks the window and reduces it to a button on the

taskbar

SW_RESTORE If the window was minimized or maximized, it would

be restored to its previous location and size

To use one of these constants, pass it to the ShowWindow() method. For example, to

minimize a window that is minimizable, you would use code as follows:

ShowWindow(SW_SHOWMINIMIZED);

Remember that this method is used to either hide or to display a control by passing the

appropriate constant, SW_HIDE to hide and SW_SHOW to display it. Here is an

example that displays a control that missed the WS_VISIBLE property when it was

created:

void CSecondDlg::OnFirstControl()

{

// TODO: Add your control notification handler code here

CWnd *First = new CWnd;

CString StrClsName = AfxRegisterWndClass(CS_VREDRAW | CS_HREDRAW,

LoadCursor(NULL, IDC_CROSS),

(HBRUSH)GetStockObject(BLACK_BRUSH),

LoadIcon(NULL, IDI_WARNING));

First->Create(StrClsName, NULL, WS_CHILD);

First->ShowWindow(SW_SHOW);

}

When the ShowWindow() method is called with the SW_SHOW value, if the control

was hidden, it would become visible; if the control was already visible, nothing would