C / C++ / MFC

How can I change background/text color of CComboBox ?

28-Mar-11 3:58

you get my 5 just for trying that hard to help someone! Smile | :)

_Flaviu24-Mar-11 8:30

Re: How can I change background/text color of CComboBox ? [modified for conversion from Q to A]

24-Mar-11 8:30

How can I change background / text color of an CComboBox , but that have CBS_DROPDOWNLIST style ?
Thank you .

Ozer Karaagac24-Mar-11 15:41

Re: How can I change background/text color of CComboBox ?

24-Mar-11 15:41

You need to handle OnCtlColor()[^] in your parent window to check (nCtlColor == CTLCOLOR_EDIT) condition for normal state.

You need to subclass CComboBox and handle OnCtlColor() to check (nCtlColor == CTLCOLOR_LISTBOX) condition for dropped down state, that is, while the list box is visible. In this case a child LB is created on the fly.

In OnCtlColor() members:

pDC->SetTextColor(clrTextColor));	
pDC->SetBkColor(clrBkColor);
if(NULL == m_pBrush)
    m_pBrush = new CBrush(clrBkColor); // this is for demonstration purposes
return (HBRUSH)*m_pBrush;              // you can handle this brush more convenient way

Don't forget to return HBRUSHes in both cases.

Albert Holguin24-Mar-11 15:43

Re: How can I change background/text color of CComboBox ?

24-Mar-11 15:43

posted your solution as a question... this isn't jeopardy! Poke tongue | ;-P

...i was about to give you a 5 when i noticed all i could choose was "good question/bad question"...

Ozer Karaagac24-Mar-11 15:58

Re: How can I change background/text color of CComboBox ?

24-Mar-11 15:58

I don't know how it could be? Thanks.
I will try to put my signature permanently. I remember, seeing you. Smile | :)

Edit:
It again didn't save it permanently. Sniff | :^)

Time is never on our side! -- Albert Holguin

_Flaviu24-Mar-11 23:36

Re: How can I change background/text color of CComboBox ?

24-Mar-11 23:36

Something I didn't do well , because at me is still white bkg/text color ...

వేంకటనారాయణ(venkatmakam)24-Mar-11 23:57

వేంకటనారాయణ(venkatmakam)

24-Mar-11 23:57

Hi, which background you are talking about whether drop down list or in combo box itself.

Re: How can I change background/text color of CComboBox ?

_Flaviu25-Mar-11 1:53

Re: How can I change background/text color of CComboBox ?

25-Mar-11 1:53

I mean drop down list , not edit box where I succeded :

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);
	}

	pDC->SetBkMode(TRANSPARENT);

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

	if(m_bAlertBkg)return m_hBrushAlert;

	return m_hBrushWhite;
}

well , I change CTLCOLOR_EDIT with CTLCOLOR_LISTBOX but with no effect ... I don't know why ...

Ozer Karaagac25-Mar-11 2:22

Re: How can I change background/text color of CComboBox ?

25-Mar-11 2:22

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.

_Flaviu25-Mar-11 2:46

Re: How can I change background/text color of CComboBox ?

25-Mar-11 2:46

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<HWND>(lParam);
		if(hWnd != 0 && hWnd != m_hWnd)
		{
			// Save the listbox handle
			m_hListBox = hWnd;
			// Do the subclassing
			m_pWndProc = reinterpret_cast<WNDPROC>(GetWindowLong(m_hListBox, GWL_WNDPROC));
			SetWindowLong(m_hListBox, GWL_WNDPROC, reinterpret_cast<long>(ComboBoxListBoxProc));
		}
	}

	return 1;
}

to get a handle to list box window ...

Ozer Karaagac25-Mar-11 3:13

Re: How can I change background/text color of CComboBox ?

25-Mar-11 3:13

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?

_Flaviu25-Mar-11 2:59

Re: How can I change background/text color of CComboBox ?

25-Mar-11 2:59

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<HWND>(lParam);
		if(hWnd != 0 && hWnd != m_hWnd)
		{
			// Save the listbox handle
			m_hListBox = hWnd;
			// Do the subclassing
			m_pWndProc = reinterpret_cast<WNDPROC>(GetWindowLong(m_hListBox, GWL_WNDPROC));
			SetWindowLong(m_hListBox, GWL_WNDPROC, reinterpret_cast<long>(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 Karaagac25-Mar-11 3:25

Re: How can I change background/text color of CComboBox ?

25-Mar-11 3:25

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 Karaagac25-Mar-11 3:36

Re: How can I change background/text color of CComboBox ?

25-Mar-11 3:36

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.

వేంకటనారాయణ(venkatmakam)25-Mar-11 2:40

వేంకటనారాయణ(venkatmakam)

25-Mar-11 2:40

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;
}

Re: How can I change background/text color of CComboBox ?

_Flaviu25-Mar-11 6:03

Re: How can I change background/text color of CComboBox ?

25-Mar-11 6:03

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 ?

_Flaviu25-Mar-11 21:27

Re: How can I change background/text color of CComboBox ?

25-Mar-11 21:27

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

mesajflaviu27-Mar-11 22:21

mesajflaviu

27-Mar-11 22:21

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;
}

Delete a view

john563224-Mar-11 3:03

john5632

24-Mar-11 3:03

Hi,

I have drived a class from CView and create class instance using new.
I am confused in deleting view.

Shell I use delete view;
Or view->DestroyWindow();

Albert Holguin24-Mar-11 4:24

24-Mar-11 4:24

Call DestroyWindow(), then delete...

john563224-Mar-11 19:45

john5632

24-Mar-11 19:45

If I do call this, I got exception.

Albert Holguin25-Mar-11 3:48

25-Mar-11 3:48

Where does the exception occur? ...check to make sure you're not deallocating the same batch of memory twice within the object. Typically the DestroyWindow call will do just that, destroy the window, but the resources don't get deallocated until you delete the object... and if you explicitly called new then odds are you explicitly have to call delete, otherwise you'll be leaking memory. Exceptions to this rule occur when the framework itself deallocates the memory, in this case usually you can find info on the framework's website (MFC=>MSDN).