MFC Toggle Radio Button Is Delayed

Question

I have a radio button that is a CButton in a CDialog. When the user clicks the radio button, the function OnClickedRadioButton is called.

Inside OnClickedRadioButton I toggle the button by calling this function:

void toggleButton(CButton& theButton)
{
    switch(theButton.GetCheck())
    {
        case BST_UNCHECKED:
        {
            theButton.SetCheck(BST_CHECKED);
            break;
        }
        case BST_CHECKED:
        {
            theButton.SetCheck(BST_UNCHECKED);
            break;
        }
        default:
        {
            theButton.SetCheck(BST_UNCHECKED);
        }
    }
}

When I compile & run the program: (i) if the radio button is checked on, I can click it to clear it. (ii) if the radio button is unchecked, I click it and nothing happens. But if I click on a different program (i.e. visual studio) and then click back on the CDialog, the radio button checks on.

I've looked & tried functions Cwnd::UpdateDialogControls and Cwnd::UpdateData, but I was not able to get these to solve my problem.

Are you aware that when you click on the radio button, and, use the SetCheck method, that you are in effect causing another OnClickedRadioButton event? — rrirower, Jan 13 '15 at 14:21
@rrirower No, I was not aware. I'm new to MFC. Do you know a good way to allow the user to toggle the radio button? — user3731622, Jan 13 '15 at 18:09
You may be using the wrong control. "Toggling" usually implies a check box because it can be 'on' or 'off'. — rrirower, Jan 13 '15 at 18:11
@rrirower Yeah, I saw that, but I want the visual of the radio button rather than the check box. — user3731622, Jan 13 '15 at 18:45
@rriower The radio button toggles now. However, if the button is unchecked & I click on another program, when I click on the CDialog that has the radio button, the radio button gets checked automatically. Any ideas what causes this? — user3731622, Jan 13 '15 at 19:43
Without seeing more, I'd say there's a bug in your code. I'd also say you're making a mistake if you're using just **one** radio button. That's not an appropriate use of that control in terms of User Interface in the context you've described. — rrirower, Jan 13 '15 at 20:07

score 0 · Answer 1 · answered Jan 13 '15 at 18:43

I believe the problem was related to @rrirower comment that SetCheck will cause another OnClickedRadioButton event.

Regardless of the root cause, the quick fix to allow my implementation to toggle a radio button betweenBST_CHECKED and BST_UNCHECKED was to set the radio button's Auto property to False.

To do this: 1) Open the resource in visual studio 2) Right-click on the radio button and select Properties 3) In the Appearance section, set the Auto property to False.

Here is the overall solution to toggle a single radio button in a subclass of CDialog (assuming you already added a Dialog resource with a radio button with ID IDC_RADIO):

1) Add radio button IDC_RADIO to the message map by placing this line

ON_BN_CLICKED(IDC_RADIO, OnBnClickedRadioButton)

between BEGIN_MESSAGE_MAP and END_MESSAGE_MAP.

2) Add the handler function to your subclass of CDialog

void OnBnClickedRadioButton()
{
    toggleButton(*(CButton*)GetDlgItem(IDC_RADIO));
}

3) Add the toggle function to your subclass of CDialog

void toggleButton(CButton& theButton)
{
    switch(theButton.GetCheck())
    {
        case BST_UNCHECKED:
        {
            theButton.SetCheck(BST_CHECKED);
            break;
        }
        case BST_CHECKED:
        {
            theButton.SetCheck(BST_UNCHECKED);
            break;
        }
        default:
        {
            theButton.SetCheck(BST_UNCHECKED);
        }
    }
}

MFC Toggle Radio Button Is Delayed

1 Answers1