How can I change background/text color of CComboBox ?

Ozer Karaagac

In above code, that is, subclassed combo box's OnCtlColor() member, you should handle CTLCOLOR_LISTBOX for dropped-down list box. May be, subclassing fails. To ensure that above code is called, put the following line on top of function. TRACE(_T("CComboBoxExt::OnCtlColor() was called with nCtlColor: %d\n"), nCtlColor); And watch output window to see above phrase.

venkatmakam

I did not tried the subclassed combobox, but according to msdn, http://msdn.microsoft.com/en-us/library/0wwk06hc(v=vs.80).aspx[^] In subclassed combobox you have to handle CTLCOLOR_LISTBOX to change the color. I tried handling OnCtlColor in dialog box,with nCtrClr == (IDOFCOMBOBOX),it is working

HBRUSH CMyDlg::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor)
{
HBRUSH hbr = CDialog::OnCtlColor(pDC, pWnd, nCtlColor);

if (pWnd->GetDlgCtrlID() == IDC_COMBO1)
{
pDC->SetBkMode(TRANSPARENT);
pDC->SetTextColor(RGB(128,128, 128));
hbr = m_brush;
}

return hbr;
}

_Flaviu

I think I am in dead point ... I use already OnCtlColorListBox but for other reason , and with other signature :

ON_MESSAGE(WM_CTLCOLORLISTBOX, OnCtlColorListBox)
...
...

LRESULT CComboBoxExt::OnCtlColorListBox(WPARAM wParam, LPARAM lParam)
{
// If the listbox hasn't been subclassed yet, do so...
if(m_hListBox == NULL)
{
HWND hWnd = reinterpret_cast(lParam);
if(hWnd != 0 && hWnd != m_hWnd)
{
// Save the listbox handle
m_hListBox = hWnd;
// Do the subclassing
m_pWndProc = reinterpret_cast(GetWindowLong(m_hListBox, GWL_WNDPROC));
SetWindowLong(m_hListBox, GWL_WNDPROC, reinterpret_cast(ComboBoxListBoxProc));
}
}

return 1;

}

to get a handle to list box window ...

_Flaviu

To make a review :

ON\_MESSAGE(WM\_CTLCOLORLISTBOX, OnCtlColorListBox)
ON\_WM\_CTLCOLOR()

LRESULT CComboBoxExt::OnCtlColorListBox(WPARAM wParam, LPARAM lParam)
{
// If the listbox hasn't been subclassed yet, do so...
if(m_hListBox == NULL)
{
HWND hWnd = reinterpret_cast(lParam);
if(hWnd != 0 && hWnd != m_hWnd)
{
// Save the listbox handle
m_hListBox = hWnd;
// Do the subclassing
m_pWndProc = reinterpret_cast(GetWindowLong(m_hListBox, GWL_WNDPROC));
SetWindowLong(m_hListBox, GWL_WNDPROC, reinterpret_cast(ComboBoxListBoxProc));
}
}

return 1;

}

HBRUSH CComboBoxExt::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor)
{
HBRUSH hbr = CComboBox::OnCtlColor(pDC, pWnd, nCtlColor);

// TODO: Change any attributes of the DC here

if(nCtlColor == CTLCOLOR\_EDIT)
{
	if(! m\_bAlertText)pDC->SetTextColor(COLOR\_BLACK);
	else pDC->SetTextColor(COLOR\_RED);
	if(! m\_bAlertBkg)pDC->SetBkColor(COLOR\_WHITE);
	else
	{
		pDC->SetBkColor(COLOR\_ALERT);
		hbr = m\_hBrushAlert;
	}
}

pDC->SetBkMode(TRANSPARENT);

// TODO: Return a different brush if the default is not desired

return hbr;

}

Ozer Karaagac

Yes. This blocks OnCtlColor(CTLCOLOR_LISTBOX). OnCtlColor() (WM_CTLCOLOR) is retained from 16Bit Windows and should be managed by MFC using newer messages like WM_CTLCOLORLISTBOX. You can also use this handler to do your work, the HDC is wParam and you need to return a valid HBRUSH. But, above return value is invalid (as brush). Probably, that listbox should paint itself if this doesn't produce a problem. In this case, how could you paint again?

Ozer Karaagac

Don't use both. Use 1st one.

LRESULT CComboBoxExt::OnCtlColorListBox(WPARAM wParam, LPARAM lParam)
{
// If the listbox hasn't been subclassed yet, do so
...

// CWnd \*pWnd = CWnd::FromHandle((HWND)lParam);
// UINT nID = npWnd->GetDlgCtrlID();
// nCtlColor = CTLCOLOR\_LISTBOX;

CDC\* pDC = CDC::FromHandle((HDC)wParam);

// move your attributes here
...

return hbr;

}

Ozer Karaagac

BTW, beware that list box is already subclassed by other reason. If it paints itself without using windows behaviour, that is, without sending WM_CTLCOLOR notifications to its parent, your attempt can be failed again.

_Flaviu

I solve the problem in the follow matter :

// header
CListBox m_ListBox;

// implementation
ON_WM_CTLCOLOR()

HBRUSH CComboBoxExt::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor)
{
HBRUSH hbr = CComboBox::OnCtlColor(pDC, pWnd, nCtlColor);

// TODO: Change any attributes of the DC here

if(nCtlColor == CTLCOLOR\_EDIT)
{
	if(m\_Edit.GetSafeHwnd() == NULL)
	{
		m\_Edit.SubclassWindow(pWnd->GetSafeHwnd());
	}
	if(! m\_bAlertText)pDC->SetTextColor(COLOR\_BLACK);
	else pDC->SetTextColor(COLOR\_RED);
	if(! m\_bAlertBkg)pDC->SetBkColor(COLOR\_WHITE);
	else
	{
		pDC->SetBkColor(COLOR\_ALERT);
		hbr = m\_hBrushAlert;
	}
}

if(nCtlColor == CTLCOLOR\_LISTBOX)
{
	if(m\_ListBox.GetSafeHwnd() == NULL)
	{
		m\_ListBox.SubclassWindow(pWnd->GetSafeHwnd());
		m\_pWndProc = reinterpret\_cast<WNDPROC>(GetWindowLong(m\_ListBox, GWL\_WNDPROC));
		SetWindowLong(m\_ListBox, GWL\_WNDPROC, reinterpret\_cast<long>(ComboBoxListBoxProc));
	}
	if(! m\_bAlertBkg)pDC->SetBkColor(COLOR\_WHITE);
	else
	{
		pDC->SetBkColor(COLOR\_ALERT);
		hbr = m\_hBrushAlert;
	}
}

pDC->SetBkMode(TRANSPARENT);

// TODO: Return a different brush if the default is not desired

return hbr;

}

I get handle of drop down list box in OnCtlColor but I still have an question : How can I change text / background color of edit while combo box have CBS_DROPDOWNLIST style ?

_Flaviu

Finllay I solve my problem , and for that I thank you very much , for you kindness and for your patient . ! Best wishes !

mesajflaviu

I solve the problem in follow way :

class CMyComboBox : public CComboBox
{
// ...
afx_msg HBRUSH CtlColor(CDC* pDC, UINT nCtlColor);
// ...
};

and

//...
ON_WM_CTLCOLOR_REFLECT()
//}}AFX_MSG_MAP
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CMyComboBox message handlers

HBRUSH CMyComboBox::CtlColor(CDC* pDC, UINT nCtlColor)
{
HBRUSH hBrush = NULL;
switch(nCtlColor)
{
case CTLCOLOR_EDIT:
{
pDC->SetBkColor(RGB(255, 0, 0));
pDC->SetTextColor(RGB(255, 255, 255));
hBrush = m_brush;
}
break;
//...
}
return hBrush;
}