Re: Resizable dialog
On Fri, 8 Feb 2008 09:42:02 -0800, Priya <Priya@discussions.microsoft.com>
wrote:
Hi guys,
Thank you for taking the time to answer my question.
The problem was that I had declared the second dialog as a member variable
of the first dialog class. I fixed it by declaring a pointer to the dialog as
the member variable and creating the dialog object just before displaying it.
Making the second dialog a member variable of any kind does not sound like
the right approach, but at the same time, it doesn't seem able to cause the
problem you described.
Initially the code was something like this:
class CDlg1 : public CDialog
{
DECLARE_DYNAMIC(CDlg1)
public:
CDlg1(CWnd* pParent = NULL); // standard constructor
virtual ~CDlg1();
// Dialog Data
enum { IDD = IDD_DIALOG1 };
protected:
virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support
virtual BOOL OnInitDialog();
afx_msg void OnSize(UINT nType, int cx, int cy);
afx_msg void OnGetMinMaxInfo(MINMAXINFO *pMMI);
afx_msg void OnOK();
POINT m_MinSize;
int m_ButtonSeparation;
CDlg2 m_cDlg2;
DECLARE_MESSAGE_MAP()
};
I changed it to:
class CDlg1 : public CDialog
{
DECLARE_DYNAMIC(CDlg1)
public:
CDlg1(CWnd* pParent = NULL); // standard constructor
virtual ~CDlg1();
// Dialog Data
enum { IDD = IDD_DIALOG1 };
protected:
virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support
virtual BOOL OnInitDialog();
afx_msg void OnSize(UINT nType, int cx, int cy);
afx_msg void OnGetMinMaxInfo(MINMAXINFO *pMMI);
afx_msg void OnOK();
POINT m_MinSize;
int m_ButtonSeparation;
CDlg2 *m_pDlg2;
DECLARE_MESSAGE_MAP()
};
If the CDlg2 is the resizable one, what is CDlg1 doing with m_MinSize and
OnGetMinMaxInfo members?
and then later on:
void CDlg1::OnOK()
{
m_pDlg2 = new CDlg2;
if (m_pDlg2)
This form of the new operator never returns NULL, so testing m_pDlg2 in
this way is unnecessary.
{
m_pDlg2->DoModal();
delete m_pDlg2;
}
}
To make your code exception-safe, use a smart pointer.
Posting this just in case someone else runs into the same problem.
This is how you should do it:
void CDlg1::OnOK()
{
CDlg2 dlg2;
dlg2.DoModal();
}
The CDlg2 object should not be a member of CDlg1; it should just be a local
variable, and there's no reason for it to be a pointer in either case.
--
Doug Harrison
Visual C++ MVP