How to display a non-modal CDialog?

Question

Can someone tell me how I could create a Non Modal Dialog in MFC's Visual c++ 6.0 and show it? I wrote this code:

CDialog dialog;
if (dialog.init(initialization values...))
   dialog.DoModal();

But it blocks my application from showing the dialog. I dont know if there exists any method or other way to do it.

Thanks

score 18 · Answer 1 · edited Sep 21 '11 at 16:59

18

/* CChildDialog class is inherited from CDialog */
CChildDialog *m_pDialog = NULL;

// Invoking the Dialog
m_pDialog = new CChildDialog();

if (m_pDialog != NULL)
{
      BOOL ret = m_pDialog->Create(IDD_CHILDDIALOG, this);

      if (!ret)   //Create failed.
      {
         AfxMessageBox(_T("Error creating Dialog"));
      }    
      m_pDialog->ShowWindow(SW_SHOW);
}

// Delete the dialog once done
delete m_pDialog;

edited Sep 21 '11 at 16:59

Fábio

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answered Feb 16 '10 at 09:53

Ramakrishna

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delete m_pDialog; it could crash the application. you can call m_pDialog->DestroyWindow (); to delete dialog. – bala Sep 17 '14 at 06:11
1

Will the dialog be delete itself if I close it? – Vinz Nov 07 '14 at 10:30
According to MSFT, dialogs are not designed for auto-cleanup. But as long as you aren't doing anything fancy with memory or handle allocations, it will normally work. https://learn.microsoft.com/en-us/cpp/mfc/tn017-destroying-window-objects?view=vs-2019 – SChalice May 20 '19 at 20:13

score 5 · Answer 2 · answered Feb 07 '13 at 16:46

5

You can call CDialog::Create and CWnd::ShowWindow like the others have suggested.

Also, keep in mind your dialog will be destroyed right after its creation if it is stored in a local variable.

answered Feb 07 '13 at 16:46

phil

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score 5 · Answer 3 · answered Feb 16 '10 at 09:46

5

Use CDialog::Create and then use CDialog::ShowWindow. You now have a modeless dialog box.

answered Feb 16 '10 at 09:46

Goz

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score 5 · Answer 4 · answered Feb 16 '15 at 13:15

In this case I find it most convenient to let it self-delete itself to handle the cleanup.

Often it's considered bad form to make "implicit" memory freeing from within a class, and not by what it created it, but I usually make exceptions for modeless dialog boxes.

That is;

Calling code:

#include "MyDialog.h"

void CMyApp::OpenDialog()
{
    CMyDialog* pDlg = new CMyDialog(this);
    if (pDlg->Create(IDD_MYDIALOG, this))
        pDlg->ShowWindow(SW_SHOWNORMAL);
    else
        delete pDlg;
}

Dialog code:

void CMapBasicDlg::OnDestroy()
{
    CDialog::OnDestroy();
    delete this; // Shown as non-modal, we'll clean up ourselves
}

This is closer to correct than the current top answer, but the delete should actually be done in OnNcDestroy. WM_DESTROY marks the start of the destruction sequence, WM_NCDESTROY marks the end. You want to wait until the latter (last message it will receive) to delete the MFC dialog. — Dennis, Dec 18 '19 at 15:50

score 3 · Answer 5 · answered Feb 16 '10 at 09:45

3

You need to call CDialog::Create instead. You will need to call DestroyWindow when you are finished with the dialog. You might also need to pass dialog messages onto the object but I can't remember if MFC handles this for you or not.

answered Feb 16 '10 at 09:45

Rob

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score 3 · Answer 6 · answered Feb 16 '10 at 09:47

3

DoModal is blocking. You have to create your dialog on the heap or make it a member of your class (this is important), call Create then call ShowWindow.

answered Feb 16 '10 at 09:47

Nikola Smiljanić

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How to display a non-modal CDialog?

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