How can I modify attribute of Frame window before creation?

CREATESTRUCT

Attributes of main frame of a doc view/dialog based application can be described in CREATESTRUCT structure. Each memeber of this structure holds the corresponding attributes of a frame window.

typedef struct tagCREATESTRUCT {
    LPVOID      lpCreateParams; /* Create param */
    HINSTANCE   hInstance;      /* Application instance */
    HMENU       hMenu;          /* Handle to menu */
    HWND        hwndParent;     /* Parent Window */
    int         cy;             /* Height */
    int         cx;             /* Width */
    int         y;              /* Y position */
    int         x;              /* X position */
    LONG        style;          /* Window styles */
    LPCSTR      lpszName;       /* Window name */
    LPCSTR      lpszClass;      /* Class name (fixed) */
    DWORD       dwExStyle;      /* Extended style */
} CREATESTRUCT, *LPCREATESTRUCT;

PreCreateWindow event

DOC view framework creates CFrameWnd object after that calls PreCreateWindow() event. Verious frame attibutes can be changed in this event. Here is an example of altering style,position and height width of the window.


BOOL CMainFrame::PreCreateWindow(CREATESTRUCT& cs)
{
    /* Call the base-class version */
   if( !CFrameWnd::PreCreateWindow(cs) )
      return FALSE;

    /* Create a window without min/max buttons or sizable border */
    cs.style = WS_OVERLAPPED | WS_SYSMENU | WS_BORDER;

    /* Size the window to 1/3 screen size and center it */
    cs.cy = ::GetSystemMetrics(SM_CYSCREEN) / 3; 
    cs.cx = ::GetSystemMetrics(SM_CXSCREEN) / 3; 
    cs.y = ((cs.cy * 3) - cs.cy) / 2; 
    cs.x = ((cs.cx * 3) - cs.cx) / 2;

   return TRUE;
}

Here is the call stack of PreCreateWindow() from MFC framework.

CMainFrame::PreCreateWindow()
CFrameWnd::GetIconWndClass()
CFrameWnd::LoadFrame()
CDocTemplate::CreateNewFrame()
CSingleDocTemplate::OpenDocumentFile()
CDocManager::OnFileNew()
CWinApp::OnFileNew()
_AfxDispatchCmdMsg()

OnCreate() event

OnCreate() event is an window event triggered by WM_CREATE message. Base function CFrameWnd::OnCreate() is called with same CREATESTRUCT pointer which is already altered in PreCreateWindow(). This is the actual creation of the frame window.

int CMainFrame::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
  if (CFrameWnd::OnCreate(lpCreateStruct) == -1)
    return -1;
  return 0;
}

Here is the call stack of OnCreate() from MFC framework.

CMainFrame::OnCreate()
CWnd::OnWndMsg()
CWnd::WindowProc()
AfxCallWndProc()
AfxWndProc()
AfxWndProcBase()

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