Advanced MFC Programming

Chapter 1. Tool Bar and Dialog Bar
We can also use Class Wizard to add new class. In order to do this, after invoking the Class Wizard,
we can click button labeled “Add Class…” then select “New…” from the popup menu. This will invoke a
dialog box that lets us add a new class to the project. We can type in the new class name, select the header
and implementation file names, and designate base class name. Unfortunately, CDialogBar is not in the list
of base classes. A workaround is that we can select CDialog as the base class, after the class is generated,
delete the unnecessary functions, and change all CDialog keywords to CDialogBar in both header and
implementation files.
Resizing Edit Control
The edit control should be resized whenever the size of its parent window changes. In order to do this,
we can trap WM_SIZE message, which is sent to a window when its size is about to change. We need to
declare an afx_msg type member function as the message handler, and implement the message mapping
using ON_WM_SIZE macro. The message handler of WM_SIZE should have the following format:
afx_msg void OnSize(UINT nType, int cx, int cy);
Here nType indicates how the window’s size will be changed (is it maximized, minimized…), cx and
cy indicate the new window size.
It is not very difficult to add message mapping macro, we can either add it manually, or ask Class
Wizard to do it for us:
BEGIN_MESSAGE_MAP(MCDialogBar, CDialogBar)
//{{AFX_MSG_MAP(MCDialogBar)
ON_WM_SIZE()
//}}AFX_MSG_MAP
END_MESSAGE_MAP()
Please note that we do not need to specify function name when using macro ON_WM_SIZE. Instead, we
must use OnSize to name the message handler of WM_SIZE.
To change a window’s size, we can call function CWnd::MoveWindow(…):
void CWnd::MoveWindow(int x, int y, int nWidth, int nHeight, BOOL bRepaint=TRUE);
We need to provide new position and size in order to call this function. Because the function is a
member of CWnd, we need to first obtain a pointer to the edit window then use it to call this function.
For controls contained in a dialog box, their window pointers can be obtained by calling function
CWnd::GetDlgItem(…). This function requires a valid control ID:
CWnd *CWnd::GetDlgItem(int nID);
The function returns a CWnd type pointer. With this pointer, we can call any member functions of CWnd
to retrieve its information or change the properties of the control.
Because we want to set the edit control’s size according to the parent window’s size (dialog bar), we
need to find a way of retrieving a window’s dimension. This can be implemented by calling another
member function of CWnd:
void CWnd::GetClientRect(LPRECT lpRect);
It is very easy to use this function. We can just declare a CRect type variable, and pass its pointer to the
above function when calling it. After this, the position and size of the window will be stored in the variable.
The following shows how message WM_SIZE is handled in the sample:
void MCDialogBar::OnSize(UINT nType, int cx, int cy)
{
CWnd *ptrWnd;
CRect rectWnd;
CDialogBar::OnSize(nType, cx, cy);
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