MFC Dialog: How to set the initial position of a modal dialog?

Q: How to set the initial position of a modal dialog?

A: There are at least two possible answers to this question. Both answers I will provide here handles the WM_INITDIALOG message.

First add a handler for the WM_INITDIALOG message to your dialog box class (this can for instance be done by using the ClassWizzard if you use a a version of VC++ prior to VC++ 2002). The message handling function for a WM_INITDIALOG message is the OnInitDialog function.

The following implementation positions the dialog at the screen coordinates x,y inside the dialog class itself:

Code:

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BOOL CYourDlg::OnInitDialog()
{
    CDialog::OnInitDialog();
    // Calculate your x and y coordinates of the upper-left corner
    // of the dialog (in screen coordinates) based on some logic

    SetWindowPos(NULL, x, y, 0, 0, SWP_NOSIZE | SWP_NOZORDER);

    return TRUE;
}

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Another possibility is to set the position when you create the dialog. To achieve this you have to add a public CPoint member variable to your dialog. This variable will hold the dialog's initial position.

Code:

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class CYourDialog : public CDialog
{
    public:
          CPoint m_point;
    //....
};

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Then you use almost the same implementation of the OnInitDialog as above. The only difference is that you use the x and y coordinates from m_point.

Code:

---

BOOL CYourDlg::OnInitDialog()

    CDialog::OnInitDialog();
 
    SetWindowPos(NULL, m_point.x, m_point.y, 0, 0, SWP_NOSIZE | SWP_NOZORDER);

    return TRUE;
}

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Now, when you create the dialog you set the m_point member to what suits you:

Code:

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    //Calculate x and y (screen coordinates)
    int x = ...;
    int y = ...;

    CYourDialog dlg;
    dlg.m_point = CPoint( x , y );

    if(dlg:DoModal() == IDOK)
    {
          //...
    }
    else
    {
          //...
    }

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