How to change the background color of an MFC edit control

Note Microsoft Visual C++ .NET 2002 and Microsoft Visual C++ .NET 2003 support both the managed code model that is provided by the Microsoft .NET Framework and the unmanaged native Microsoft Windows code model. The information in this article applies only to unmanaged Visual C++ code.

Summary

To change the background color of an edit control in an MFC application, you must override the OnCtlColor() message-handling function of the window containing the edit control.

In the new OnCtlColor() function, set the background color and return a handle to a brush that will be used for painting the background. This must be done in response to receiving both the CTLCOLOR_EDIT and CTLCOLOR_MSGBOX messages in the OnCtlColor() function.

This is also documented in the "Class Library Reference" under CWnd::OnCtlColor().

More Information

The sample code below uses a CDialog-derived class to demonstrate the process. Class Wizard was used to generate message-handling functions for the WM_CTLCOLOR and WM_DESTROY messages. These functions are called CEditDialog::OnCtlColor() and CEditDialog::OnDestroy(), respectively.

Note In Visual C++ .NET you can add the WM_CTLCOLOR and WM_DESTROY handlers for the dialog object from the Properties Window. All the available messages for the dialog are listed in the Messages tab.

Sample code

      // editdlg.h : header file
//

////////////////////////////////////////////////////////////////////////
///
// CEditDialog dialog

class CEditDialog : public CDialog
{
// Construction
public:
CEditDialog(CWnd* pParent = NULL); // standard constructor

// Add a CBrush* to store the new background brush for edit controls.
CBrush* m_pEditBkBrush;

// Dialog Data
//{{AFX_DATA(CEditDialog)
enum { IDD = IDD_EDITDIALOG };
// NOTE: The ClassWizard will add data members here.
//}}AFX_DATA

// Overrides
// ClassWizard generated virtual function overrides
//{{AFX_VIRTUAL(CEditDialog)
protected:
virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support
//}}AFX_VIRTUAL

// Implementation
protected:

// Generated message map functions
//{{AFX_MSG(CEditDialog)
afx_msg HBRUSH OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor);
afx_msg void OnDestroy();
//}}AFX_MSG
DECLARE_MESSAGE_MAP()
};

// editdlg.cpp : implementation file
//

#include "stdafx.h"
#include "mdi.h"
#include "editdlg.h"

#ifdef _DEBUG
#undef THIS_FILE
static char BASED_CODE THIS_FILE[] = __FILE__;
#endif

//////////////////////////////////////////////////////////////////////
// CEditDialog dialog

CEditDialog::CEditDialog(CWnd* pParent /*=NULL*/)
: CDialog(CEditDialog::IDD, pParent)
{
//{{AFX_DATA_INIT(CEditDialog)
// NOTE: The ClassWizard will add member initialization here.
//}}AFX_DATA_INIT

// Instantiate and initialize the background brush to black.
m_pEditBkBrush = new CBrush(RGB(0, 0, 0));
}

void CEditDialog::DoDataExchange(CDataExchange* pDX)
{
CDialog::DoDataExchange(pDX);
//{{AFX_DATA_MAP(CEditDialog)
// NOTE: The ClassWizard will add DDX and DDV calls here.
//}}AFX_DATA_MAP
}

BEGIN_MESSAGE_MAP(CEditDialog, CDialog)
//{{AFX_MSG_MAP(CEditDialog)
ON_WM_CTLCOLOR()
ON_WM_DESTROY()
//}}AFX_MSG_MAP
END_MESSAGE_MAP()

//////////////////////////////////////////////////////////////////////
// CEditDialog message handlers

HBRUSH CEditDialog::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor)
{
switch (nCtlColor) {

case CTLCOLOR_EDIT:
case CTLCOLOR_MSGBOX:
// Set color to green on black and return the background
brush.
pDC->SetTextColor(RGB(0, 255, 0));
pDC->SetBkColor(RGB(0, 0, 0));
return (HBRUSH)(m_pEditBkBrush->GetSafeHandle());

default:
return CDialog::OnCtlColor(pDC, pWnd, nCtlColor);
}
}

void CEditDialog::OnDestroy()
{
CDialog::OnDestroy();

// Free the space allocated for the background brush
delete m_pEditBkBrush;
}
Lastnosti

ID članka: 117778 – Zadnji pregled: 21. nov. 2006 – Revizija: 1

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