Visual C++ and MFC Programming 2nd Edition

Chapter 12: Dialog-Based Windows Visual C++ and MFC Fundamentals

BOOL CMainFrame::PreCreateWindow(CREATESTRUCT& cs)

{

if( !CFrameWnd::PreCreateWindow(cs) )

return FALSE;

// TODO: Modify the Window class or styles here by modifying

// the CREATESTRUCT cs

cs.style &= ~WS_MINIMIZEBOX;

return TRUE;

}

In the same way, you can remove the system maximize button.

If you allow the system buttons, the user can minimize and maximize the window at will.

To do this, besides using the system buttons, the user can also double-click the title bar of

the window or click its Maximize menu item either from the window's system icon or

after right-clicking its button on the Taskbar. When the window is maximized, the frame

is resized to occupy the whole monitor area, starting from the top-left corner as the

origin.

When the user decides to maximize a window, the frame sends a

WM_GETMINMAXINFO message which appears like "The user wants to maximize

me. What should I do?". This message produces the OnGetMinMaxInfo() event. If the

application does not give any specific instruction, the window gets maximized. If you

want to do something before the window is formally maximized, you can intercept

OnGetMinMaxInfo() event. Remember that, if you want to prevent the window from

being minimized or maximized, you should remove the Minimize

(WS_MINIMIZEBOX) or the Maximize (WS_MAXIMIZEBOX) buttons from its

style.

If you want to control the minimum and/or maximum size that a window can have when

the user wants to maximize it, set the desired size in the OnGetMinMaxInfo() event. It

syntax is:

afx_msg void OnGetMinMaxInfo(MINMAXINFO FAR* lpMMI);

The information pertinent to a window's maximized size, including the maximum size it

can have, is stored in a structure called MINMAXINFO. The MINMAXINFO structure is

defined as follows:

typedef struct tagMINMAXINFO {

POINT ptReserved;

POINT ptMaxSize;

POINT ptMaxPosition;

POINT ptMinTrackSize;

POINT ptMaxTrackSize;

} MINMAXINFO;

A variable of MINMAXINFO type is passed to the OnGetMinMaxInfo() event.

The ptReserved member variable is reserved and never used.

The ptMaxSize value is the maximum width and the maximum height. To specify this

value, you can call the x member variable of the point value of ptMaxSize and assign the

desired value. Here is an example: