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CWnd::OnCtlColor

The framework calls this member function when a child control is about to be drawn.


afx_msg HBRUSH OnCtlColor(
   CDC* pDC,
   CWnd* pWnd,
   UINT nCtlColor 
);
pDC

Contains a pointer to the display context for the child window. May be temporary.

pWnd

Contains a pointer to the control asking for the color. May be temporary.

nCtlColor

Contains one of the following values, specifying the type of control:

  • CTLCOLOR_BTN   Button control

  • CTLCOLOR_DLG   Dialog box

  • CTLCOLOR_EDIT   Edit control

  • CTLCOLOR_LISTBOX   List-box control

  • CTLCOLOR_MSGBOX   Message box

  • CTLCOLOR_SCROLLBAR   Scroll-bar control

  • CTLCOLOR_STATIC   Static control

OnCtlColor must return a handle to the brush that is to be used for painting the control background.

Most controls send this message to their parent (usually a dialog box) to prepare the pDC for drawing the control using the correct colors.

To change the text color, call the SetTextColor member function with the desired red, green, and blue (RGB) values.

To change the background color of a single-line edit control, set the brush handle in both the CTLCOLOR_EDIT and CTLCOLOR_MSGBOX message codes, and call the CDC::SetBkColor function in response to the CTLCOLOR_EDIT code.

OnCtlColor will not be called for the list box of a drop-down combo box because the drop-down list box is actually a child of the combo box and not a child of the window. To change the color of the drop-down list box, create a CComboBox with an override of OnCtlColor that checks for CTLCOLOR_LISTBOX in the nCtlColor parameter. In this handler, the SetBkColor member function must be used to set the background color for the text.

Note Note:

This member function is called by the framework to allow your application to handle a Windows message. The parameters passed to your function reflect the parameters received by the framework when the message was received. If you call the base-class implementation of this function, that implementation will use the parameters originally passed with the message and not the parameters you supply to the function.

// This OnCtlColor handler will change the color of a static control
// with the ID of IDC_MYSTATIC. The code assumes that the CPenWidthsDlg
// class has an initialized and created CBrush member named m_brush.
// The control will be painted with red text and a background
// color of m_brush.
HBRUSH CPenWidthsDlg::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor)
{
   // Call the base class implementation first! Otherwise, it may
   // undo what we're trying to accomplish here.
   HBRUSH hbr = CDialog::OnCtlColor(pDC, pWnd, nCtlColor);

   // Are we painting the IDC_MYSTATIC control? We can use
   // CWnd::GetDlgCtrlID() to perform the most efficient test.
   if (pWnd->GetDlgCtrlID() == IDC_MYSTATIC)
   {
      // Set the text color to red
      pDC->SetTextColor(RGB(255, 0, 0));

      // Set the background mode for text to transparent 
      // so background will show thru.
      pDC->SetBkMode(TRANSPARENT);

      // Return handle to our CBrush object
      hbr = m_brush;
   }

   return hbr;
}


Header: afxwin.h

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