CCheckComboBox II

PJ Arends

4.75/5 (8 votes)

Dec 29, 2003

CPOL

3 min read

126404

5811

A ComboBox that has a checkbox by each of its items.

Sample Image - CheckComboBox.png

Introduction

This control is actually a modification of the CCheckComboBox class that was written by Magnus Egelberg, Lunalogik. Magnus' control had just about everything I was looking for in a CheckComboBox except one small feature. It did not allow you to check an item in the static text portion of the combo box, you had to drop down the list box in order to make the selections. All the drawing code in this class was written by Magnus. The only additions I made was the code to handle the check box in the static text area, and I removed the dependency on the item data for storing the check state of the items. It is now stored in a CByteArray member variable.

Usage

To use the control, you have to include the CheckComboBox.h header file and add the CheckComboBox.cpp file to your project.

If the control is used on a dialog, it has to have the CBS_DROPDOWNLIST and CBS_OWNERDRAWVARIABLE combo box styles.

Command Notifications

In addition to the regular CBN_* notifications that are generated by the combobox, the CCheckComboBox will also generate a BN_CLICKED notification whenever a user changes the check state of a check box. You can handle the BN_CLICKED notification exactly the same way you would handle it if it was generated by a button control. Use the GetCurSel() member function to get the index of the checkbox that generated the BN_CLICKED notification.

BEGIN_MESSAGE_MAP(CCCheckCombo_demoDlg, CDialog)
    // use the ON_BN_CLICKED macro to catch the BN_CLICKED
    // command that is generated by the CCheckComboBox
    ON_BN_CLICKED(IDC_COMBO1, OnCheckBox)
END_MESSAGE_MAP()
 
...
 
void CCCheckCombo_demoDlg::OnCheckBox()
{
    int sel = m_CheckCombo.GetCurSel();
    CString text;
    m_CheckCombo.GetLBText(sel, text);
    BOOL checked = m_CheckCombo.GetCheck(sel);
    TRACE(_T("Item %d (\"%s\") was %s \n"), sel, 
       text, checked ? _T("checked") : _T("unchecked"));
}

Member Functions

These are the public member functions added to the CCheckComboBox. All CComboBox member functions can also be used.

BOOL Create(DWORD dwStyle, const RECT& rect, CWnd* pParentWnd, UINT nID)

Use this function to dynamically create a CCheckComboBox control. The required combo box styles are set automatically.

Return value

Nonzero if successful, otherwise 0.

Parameters

`dwStyle`	The `WS_` and `CBS_` styles for the control. The `CBS_DROPDOWNLIST` and `CBS_OWNERDRAWVARIABLE` styles are set automatically if they are not specified.
`rect`	The position and size of the `CCheckComboBox`.
`pParentWnd`	Specifies the `CCheckComboBox`’s parent window (usually a `CDialog`). It must not be `NULL`.
`nID`	Specifies the `CCheckComboBox`’s control ID.

BOOL GetCheck(int nIndex)
Use this function to get the checked state of the check box at the specified zero based index.

Return value

TRUE if the check box is checked, otherwise FALSE.

Parameters

nIndex The zero based index of the check box
BOOL SetCheck(int nIndex, BOOL bCheck = TRUE)
Sets the check state for the check box at the specified zero based index.

Return value

The previous check state. TRUE if the check box was checked, FALSE if not.

Parameters

nIndex The zero based index of the check box

bCheck The new check state. TRUE to check the check box, FALSE to uncheck it.
void CheckAll(BOOL bCheck = TRUE)
Sets the checked state of all the check boxes in the CCheckComboBox control.

Return value

There is no return value.

Parameters

bCheck The new check state. TRUE to check the check boxes, FALSE to uncheck them.

`nIndex`	The zero based index of the check box
`bCheck`	The new check state. `TRUE` to check the check box, `FALSE` to uncheck it.