C / C++ / MFC

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

Ozer Karaagac

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?

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

_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

Ozer Karaagac

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;
}

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

Ozer Karaagac25-Mar-11 3:36

Ozer Karaagac

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.

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

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

Albert Holguin

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

Albert Holguin

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).

STL : Map.Insert always sort the inserted key - How to prevent this

Richard MacCutchan24-Mar-11 5:47

Richard MacCutchan

24-Mar-11 5:47

Use view->DestroyWindow(); to destroy the visible Window (or View) associated with the instance of your CView derived class. Then once the window has been disposed of properly you can use delete, if appropriate, to dispose of your view object.

I must get a clever new signature for 2011.

pandit8424-Mar-11 0:35

pandit84

24-Mar-11 0:35

Hi ,

I am having a std map object. I have added key and value in the following order.

mymap.insert (pair<int,int>(10,20)) ;   //Key,value
mymap.insert (pair<int,int>(5,20)) ;
mymap.insert (pair<int,int>(104,20)) ;
mymap.insert (pair<int,int>(1,20)) ;

But while extracting the data from map I am getting this data in a sorted order (sorted by Key order). How can I prevent this . I am passing the data from this map to a device which needs the data as is from my map. Please help

Re: STL : Map.Insert always sort the inserted key - How to prevent this

C^hris L^osinger24-Mar-11 1:03

C^hris L^osinger

24-Mar-11 1:03

maps are always sorted. the tree structure that they use internally requires it.

if you want an unsorted container, use a vector (or a list).

image processing toolkits | batch image processing

Re: STL : Map.Insert always sort the inserted key - How to prevent this

Stefan_Lang30-Mar-11 1:51

Stefan_Lang

30-Mar-11 1:51

If you want to maintain the order of insertion, then you could create a list alongside your map. Each insert will give you an iterator in return, which references the newly inserted element. Store this element in your list, and you're done. If you want to retrieve your elements in order of insertion, use the list. If you want it ordered by key, or just want to retrieve a single object with a key, use your map.

class MyMap {
    std::map<int,int> m_map;
    std::list<pair<int,int> > m_list;
public:
    typedef std::list<pair<int,int> >::iterator insert_iterator;
    typedef std::map<int,int>::iterator key_iterator;
    void insert(int key, int value) {
        m_list.push_back(m_map.insert(pair<int,int>(key, value)));
    }
    insert_iterator ibegin() { return m_list.begin(); }
    insert_iterator iend() { return m_list.end(); }
    key_iterator kbegin() { return m_map.begin(); }
    key_iterator kend() { return m_map.end(); }
};

Note that you will have to dereference your insert_iterator twice: once to get the list element which is an iterator to the map, and a second time to get the actual element of the map:

MyMap mymap;
mymap.insert(5, 15);
mymap.insert(100, 20);
mymap.insert(34, 30);
for (MyMap::key_iterator kit = mymap.kbegin(); kit != mymap.kend(); ++kit)
    std::cout << (*kit).second << std::endl; // prints 15 30 20
for (MyMap::insert_iterator it = mymap.ibegin(); it != mymap.iend(); ++it)
    std::cout << (*(*it)).second << std::endl; // prints 15 20 30

Of course, this mechanism breaks down once you start erasing elements from your map - the moment you do this, the accompanying iterators stored in the list will be invalidated! You could of course search for these elements and remove them from the list, but that would be very inefficient and might negate the efficiency that you gained from using a map in the first place.

In that case you might be better off to just use a list without a map, and sequentially search for the key when you want to retrieve a particular element. Note that you can use the std::find() methods to search for particular elements, you just have to provide a comparator that specifically compares the key. If you have a compiler that supports C++0x you might even use an unnamed lambda to provide the comparator instead of having to define a function object class.

How to reduce Flickering ?

002comp23-Mar-11 22:47

002comp

23-Mar-11 22:47

Hello Friends
I am using drawImage from GDIPLUS in OnPaint().And Mine image is getting flickered too much.How can i reduce it?

Thanks & Regards
Yogesh

CPallini23-Mar-11 23:00

CPallini

23-Mar-11 23:00

You may use double buffering technique. Have a look at (one of) the following CodeProject articles:
http://www.codeproject.com/info/search.aspx?artkw=double+buffering&sbo=kw[^].
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

Maximilien24-Mar-11 2:56

Maximilien

24-Mar-11 2:56

+1 for using the CP search instead of google! Big Grin | :-D

Watched code never compiles.

Re: How to reduce Flickering ? [modified]

CPallini24-Mar-11 4:27

CPallini

24-Mar-11 4:27

Thanks.

Cool_Dev24-Mar-11 0:22

Cool_Dev

24-Mar-11 0:22

in addition, handle WM_ERASEBACKGROUND message and simply return TRUE from there without calling base class's message handler. This will discard the flickering due to background painting. Remember, you have to paint the background from OnPaint (use double buffering Smile | :)

)

modified on Thursday, March 24, 2011 9:13 AM

Nitheesh George24-Mar-11 2:02

Nitheesh George

24-Mar-11 2:02

Hi
Also create a memory DC and select this image to this DC. And use this DC as the Source in API BitBlt, StretchBitBlt etc.

Hope this helps

Nitheesh George

http://www.simpletools.co.in