HOWTO: Change the Color of an MFC Child Control Class
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The information in this article applies to:
The Microsoft Foundation Classes (MFC), used with:
Microsoft Visual C++ for Windows, 16-bit edition, versions 1.0, 1.5, 1.51, 1.52
Microsoft Visual C++, 32-bit Editions, versions 1.0, 2.0, 2.1, 2.2, 4.0, 5.0, 6.0
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SUMMARY
To change the color scheme of a standard class of controls in an MFC-based application, follow these steps:
Derive a class from the standard control class, such as CEdit.
Define a static member variable of class CBrush to be the brush for that class of controls.
Override the control's member function OnChildNotify(), handle the message WM_CTLCOLOR, and use the new brush. In MFC 4.0, this could also be done by using an ON_WM_CTLCOLOR_REFLECT handler.
NOTE: In 32-bit Windows, the controls do not send the WM_CTLCOLOR message. They send WM_CTLCOLORxxx messages, where xxx is the type of control. For example, static control sends the WM_CTLCOLORSTATIC message.
MORE INFORMATION
This approach works for list boxes, the list boxes of combo boxes, button controls, edit controls, static controls, message boxes, and dialog boxes. (This approach does not work for push buttons and the CRichEditCtrl. The color of a standard CButton object is determined by system settings. If you want a different color for push buttons, use a CBitmapButton. To change the color of a CRichEditCtrl use its member functions.)
For an alternative approach, please see the following article in the Microsoft Knowledge Base:
Q117778 Changing the Background Color of an MFC Edit Control
It illustrates how to change the background color of a control in the parent window.
When a control is about to be redrawn, it sends the message WM_CTLCOLOR to its parent. This message is handled by the OnCtlColor() member function of the parent.
OnCtlColor() allows the parent to modify the drawing of the child by:
Specifying the background brush.
Changing the text color.
Making other changes to the device context with which the drawing is to be done.
One of the first things the default implementation of OnCtlColor() does is to call the OnChildNotify() member function of the child that sent the message. By overriding this OnChildNotify() member function, the child can determine its own color scheme, instead of taking it from the parent.
The following sample code defines a class of edit controls with red text on a green background. The sample code shows only what is necessary to change the color of the controls. It does not include code generated by the ClassWizard.
Sample Code
Code:
/* Compile options needed: Default
*/
// NOTE: The sample code is for 32-bit. It has to be modified for
// 16-bit. See the comment below.
// ** MYEDIT.H **
class CMyEdit : public CEdit
{
public:
BOOL OnChildNotify(UINT message, WPARAM wParam, LPARAM Param,
LRESULT* pLResult);
protected:
static CBrush m_brush;
};
// ** MYEDIT.CPP **
#include "myedit.h"
// Create a green brush for the background for the class of controls:
CBrush CMyEdit::m_brush(RGB(0,128,0));
BOOL CMyEdit::OnChildNotify(UINT message, WPARAM wParam,
LPARAM lParam, LRESULT* pLResult)
{
// If "message" is not the message you're after, do default processing:
// For 16-bit applications change WM_CTLCOLOREDIT to WM_CTLCOLOR
if (message != WM_CTLCOLOREDIT)
{
return CEdit::OnChildNotify(message,wParam,lParam,pLResult);
}
// Set the text foreground to red:
HDC hdcChild = (HDC)wParam;
SetTextColor(hdcChild, RGB(0,0,255));
// Set the text background to green:
SetBkColor(hdcChild, RGB(0,128,0));
// Send what would have been the return value of OnCtlColor() - the
// brush handle - back in pLResult:
*pLResult = (LRESULT)(m_brush.GetSafeHandle());
// Return TRUE to indicate that the message was handled:
return TRUE;
}
