CComboBox with CheckBox like an Item

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Introduction

This example shows how to implement your own combobox control with check boxes like a list item.

Using the Code

There was a need to create a combobox with the ability to select several elements.
Since the MFC does not have such a control, I had to implement my control on the basis of a combobox.

This control is based on standard CComboBox.

For using it, just create a combobox in your form with special attributes:

• Owner Draw - Variable
• Has Strings - True

Include Combo.h and Combo.cpp to your project.

In these files, ChkCombo class is described.

Create the example of this class in your application.

ChkCombo m_Combo;

The next step for using it is that you have to associate the standard ComboBox with this class.

void CCCOMBODlg::DoDataExchange(CDataExchange* pDX)
{
    DDX_Control(pDX, IDC_COMBO1, m_Combo);
                ......
    CDialogEx::DoDataExchange(pDX);
}

So, now all ready for using this control.

At first, you need to add some strings in ChkCombo and for example, check some items.

m_Combo.AddString(L"Red");
m_Combo.AddString(L"Green");
m_Combo.AddString(L"Blue");
m_Combo.AddString(L"Black");
m_Combo.AddString(L"White");
m_Combo.AddString(L"Yellow");
m_Combo.AddString(L"Brown");

m_Combo.SetCheck(0, TRUE);
m_Combo.SetCheck(1, TRUE);
m_Combo.SetCheck(2, TRUE);

For send events, this control has a special message with code THIS_CHECKED.

This message will be sent every time you check/uncheck some item.

Example of how to use it:

BEGIN_MESSAGE_MAP(CCCOMBODlg, CDialogEx)
...........................................................
    ON_MESSAGE(THIS_CHECKED, &CCCOMBODlg::OnChecked)

...........................................................

END_MESSAGE_MAP()

LRESULT CCCOMBODlg::OnChecked(WPARAM wp, LPARAM lp)
{
    int ID = (DWORD)lp;
    int index = LOWORD(wp);
    bool flag = HIWORD(wp);
    wchar_t text_s[32];
    memset(text_s, 0, 32 * sizeof(wchar_t));
    wsprintf(text_s, L"%d __ %d", index, flag);
    if(ID == IDC_COMBO1)
        GetDlgItem(IDC_STATIC_CHK)->SetWindowText(text_s);
    return 0;
}

This example shows how to get control ID and get information about what item changed and the current state.

I hope this class can help you in your work. :)

History

• 4^th December, 2020: Initial version