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CListBox ownerdraw

Posted on 2000-04-05
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Last Modified: 2013-11-20
I'm writing a VC++ Dialog type application. Since I want to have some listbox with black background and white text, I created my own class  CModListBox which is based on CListBox.

so.. the followng listed what I did:
1. Create a class:  Class CModListBox : public CListBox
2. Add virtual function Drawitem and I use exactly the same code list in MSDN:
void CModListBox::DrawItem(LPDRAWITEMSTRUCT lpDrawItemStruct)
{
      // TODO: Add your code to draw the specified item
   //ASSERT(lpDrawItemStruct->CtlType == ODT_LISTBOX);
   LPCTSTR lpszText = (LPCTSTR) lpDrawItemStruct->itemData;
   //ASSERT(lpszText != NULL);  
   CDC dc;
   dc.Attach(lpDrawItemStruct->hDC);
   // Save these value to restore them when done drawing.
   COLORREF crOldTextColor = dc.GetTextColor();
   COLORREF crOldBkColor = dc.GetBkColor();
   // If this item is selected, set the background color
   // and the text color to appropriate values. Also, erase
   // rect by filling it with the background color.
   if ((lpDrawItemStruct->itemAction | ODA_SELECT) &&
      (lpDrawItemStruct->itemState & ODS_SELECTED))  
   {
      dc.SetTextColor(RGB(255,255,255));
      dc.SetBkColor(RGB(0,0,25));
      dc.FillSolidRect(&lpDrawItemStruct->rcItem,
         RGB(50,50,50));  
   }
   else
      dc.FillSolidRect(&lpDrawItemStruct->rcItem,RGB(20,20,20));
   // If this item has the focus, draw a red frame around the   // item's rect.
   if ((lpDrawItemStruct->itemAction | ODA_FOCUS) &&
      (lpDrawItemStruct->itemState & ODS_FOCUS))  
   {
      CBrush br(RGB(255, 0, 0));
      dc.FrameRect(&lpDrawItemStruct->rcItem, &br);  
   }   // Draw the text.
   dc.DrawText(      lpszText,      strlen(lpszText),
      &lpDrawItemStruct->rcItem,      DT_CENTER|DT_SINGLELINE|DT_VCENTER);
   // Reset the background color and the text color back to their
   // original values.   dc.SetTextColor(crOldTextColor);
   dc.SetBkColor(crOldBkColor);  
   dc.Detach();
}




3. Add a variable CModListBox m_ctlScheme in my main dialog box
class

4. Add this line in the OnCreate() (of main dialog box)
      m_ctlScheme.Create(WS_CHILD|WS_VISIBLE|WS_BORDER|WS_VSCROLL|LBS_OWNERDRAWVARIABLE,CRect(400,550,600,590),this, IDC_LISTSCHEME);

.......

Then whenever I try to click on the listbox, or try to use "addstring" to do something to the listbox, it gives an error msg to me.
Is there anything else I need to do ??  This is the first time I create a class to use the ownerdraw function so... :)
0
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Question by:rw8
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11 Comments
 
LVL 10

Accepted Solution

by:
RONSLOW earned 100 total points
ID: 2688415
don't create it like that.

Put a normal listbox in your dialog (make sure it is owner-drawn etc).

Then use DDX_Control to subclass it.  Alternatively, use SubclassWindow if you don't like MFC's easy dataexchange and ClassWizard

Then that listbox in the dialog will be associated with you m_ctlScheme and m_ctlScheme will get the message etc.

BTW: instead of attaching and detaching from a DC, use this...

CDC* pDC = CDC::FromHandle(lpDIS->hDC);

then use pDC-> and no need to detatch, delete etc the pDC.


0
 
LVL 10

Expert Comment

by:RONSLOW
ID: 2688416
You _could_ use OnCtlColor to change the colour (background and text) instead.  Then you don't need to make it owner drawn.

0
 

Author Comment

by:rw8
ID: 2688714
RONSLOW,
can you give me an example of how to use OnCtlColor to change the colour? Do I need to derive a new class?
0
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LVL 3

Expert Comment

by:V_Bapat
ID: 2688946
Hi rw8
   RONSLOW is right. Just for changing the text and background color you need not make is owner drawn. OnCtlColor works but if I am right, text color and only background color of the text changes and not the background color of the control.
   Take a look at the Technical article 62(TN062) in MSDN. You will find a step by step procedure to change the text and bkground color of an edit box. Just apply it for the list box.

All the best.

Vicky
0
 

Author Comment

by:rw8
ID: 2691571
Yes. It works! But I have a problem... the listbox remains the default colour (black text over white background) unless I put "invalidate" in the CtlColor function..  however, if I do this.. the listbox keeps on redrawing itself ..
should I put Invalidate() in somewhere else?
0
 
LVL 10

Expert Comment

by:RONSLOW
ID: 2691729
show us your code .. that behaviour shouldn't be happening
0
 

Author Comment

by:rw8
ID: 2691776
this is the class I created (base on CListBox)

CBlackListBox::CBlackListBox()
{
      m_text = RGB(255, 0, 0 );
    m_background = RGB( 0, 255, 0 );
    m_brBkgnd.CreateSolidBrush( m_background );
}

CBlackListBox::~CBlackListBox()
{
}


BEGIN_MESSAGE_MAP(CBlackListBox, CListBox)
      //{{AFX_MSG_MAP(CBlackListBox)
      ON_WM_CTLCOLOR_REFLECT()
      //}}AFX_MSG_MAP
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CBlackListBox message handlers

HBRUSH CBlackListBox::CtlColor(CDC* pDC, UINT nCtlColor)
{
      // TODO: Change any attributes of the DC here
     pDC->SetTextColor( m_text );    // text
     pDC->SetBkColor( m_background );    // text bkgnd
      
     return m_brBkgnd;                // ctl bkgnd
      // return NULL;

}


and I add a ListBox in my main dialog box and attach a CBlacklistbox ctl varible to it.. and I didn't change any settings of the the listbox.
0
 
LVL 10

Expert Comment

by:RONSLOW
ID: 2691792
On first inspection it looks ok .. I'll give it a try when I havea few mintes.

0
 

Author Comment

by:rw8
ID: 2691815
wait ronslow, I just created another listbox and it seems ok now. I'll do some more tests now
0
 
LVL 10

Expert Comment

by:RONSLOW
ID: 2691832
the plot thickens....
0
 

Author Comment

by:rw8
ID: 2691976
Thanx RONSLOW. It's working now. And thanx  V Bapat too. :)
0

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