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Changing the background color of a read-only edit control

, 18 Jan 2005 125.9K 4.3K 35
An article on very easily changing the color of a read-only edit control.
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Introduction

This is my first article. So bear with me. I know it is a simple control but I spent quite a lot of time figuring this out. I hope someone can read this and figure it out quicker.

The Problem

I needed a read-only text box. I created one using the CEdit control. Problem was that, it had a grey background. There is no option or function to change it directly.

The Solution

I derived a class from CEdit called CReadOnlyEdit. I intercepted the background ON_WM_CTLCOLOR_REFLECT() message. This message's function looks like this:

HBRUSH CReadOnlyEdit::CtlColor(CDC* pDC, UINT nCtlColor) 
{
	// TODO: Return a non-NULL brush if the parent's 
	//handler should not be called
	return NULL;
}

To change the background color of the EditBox, instead of returning NULL for the function above, I returned a brush with the color I wanted for the background. Also if you notice in the function, above one of the parameters is a pointer to the Device Context (pDC) of the control. I used the pDC->SetTextColor(COLORREF rgb) function to change the text color. I then ran into a slight problem. The background changed to the correct color and the text did as well but the background of the text stayed white. This was a simple fix. I simply set the background color of the text using pDC->SetBkColor(COLORREF rgb) function. This is my modified function:

HBRUSH CReadOnlyEdit::CtlColor(CDC* pDC, UINT nCtlColor) 
{
	// TODO: Return a non-NULL brush if the parent's 
	//handler should not be called

	//set text color
	pDC->SetTextColor(m_crText);

	//set the text's background color
	pDC->SetBkColor(m_crBackGnd);

  //return the brush used for background this sets control background
  return m_brBackGnd;
}

As you can see my control has three variables: COLORREF m_crText, COLORREF m_crBackGnd, and CBrush m_brBackGnd. I added two functions to my control, one to change the background color (and update the brush) and one to change the text color. Those two functions look like this:

void CReadOnlyEdit::SetBackColor(COLORREF rgb)
{
	//set background color ref (used for text's background)
	m_crBackGnd = rgb;
	
	//free brush
	if (m_brBackGnd.GetSafeHandle())
       m_brBackGnd.DeleteObject();
	//set brush to new color
	m_brBackGnd.CreateSolidBrush(rgb);
	
	//redraw
	Invalidate(TRUE);
}
void CReadOnlyEdit::SetTextColor(COLORREF rgb)
{
  //set text color ref
  m_crText = rgb;

  //redraw
  Invalidate(TRUE);
}

The reason I have a COLORREF background variable is because to change the background color of the device context I need a COLORREF. A problem I ran into was, the entire edit control was not being colored right away, this is why I added the Invalidate(TRUE) call to repaint the control.

That's all there was to it. By the way, my control doesn't set a background or text color by default. This can easily be done in the constructor.

Using the code

Dialog Based:

Create a CEdit control. Control double-click it. The Add Member Variable dialog appears. Choose Control for the Category and CEdit for the variable type. Set the variable name to something like m_wndEdit. When modifying the control, remember m_wndEdit is the control not a string containing the window text. To access the text you will have to use the proper functions for the control (ie. CEdit::SetWindowText()).

Programmatically:

The simplest way I can think of to use this is just change all the CEdit controls you want to be read-only to CReadOnlyEdit.

Changing the colors:

To change the background and text color of the control using the SetBack Color(COLORREF rgb) and SetTextColor(COLORREF rgb) functions. In the demo I use a CColorDialog to get a color. The following is code from my demo. It is located in the Change Back Color button's click function:

void CReadOnlyDlg::OnBack() 
{	
	// call color dialog and change background color
	CColorDialog dlg;
	if (dlg.DoModal() == IDOK)
		m_wndReadOnly.SetBackColor(dlg.GetColor());
	
}

Where m_wndReadOnly is the CReadOnlyEdit control.

Note: My control doesn't set the read-only flag, you have to do this yourself in the CReadOnlyEdit::Create function or in the dialog control properties. Also, this can be done with the CEdit::SetReadOnly(BOOL) function.

History

  • Jan 21 2005 - Update.
    • Fixed Bugs.
    • Added SetBackColor and SetTextColor functions.
  • Jan 18 2005 - Posted
    • Basic control, changed background color to white.

License

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About the Author

Kevin Bond

Canada Canada
I am 20 years old and I live in Kitchener, Ontario. I have been programming since I was 10 years old. I started with QBasic, then up to Visual Basic, and finally C++. I am an avid programmer of Windows as well. Besides that, I am also interested in automation, PLCs, and electronics. I will be attending Conestoga College in Sept. 2005 for their Mechanical Engineering: Automation and Robotics program. I hope to someday have a job where I can incorporate my skills with programming Windows with the skills I learn in that program.

Comments and Discussions

 
Questionhello Kevin Bond Pin
wangandy9-Aug-11 4:02
memberwangandy9-Aug-11 4:02 
GeneralThanks Pin
12017968028-Sep-10 16:22
member12017968028-Sep-10 16:22 
QuestionReadonly Textbox inside the GroupBox Control Pin
razhia11-Nov-09 17:34
memberrazhia11-Nov-09 17:34 
GeneralMandou ver! Pin
L4U80Y9-Nov-09 9:11
memberL4U80Y9-Nov-09 9:11 
Generalhaha Pin
caolvchong17-Dec-08 19:14
membercaolvchong17-Dec-08 19:14 
GeneralMuch easier and quicker method Pin
mr. bleh30-Oct-07 10:45
membermr. bleh30-Oct-07 10:45 
GeneralThank you Pin
miniiiii29-Jul-07 19:40
memberminiiiii29-Jul-07 19:40 
GeneralThank you Pin
compex8-Jan-07 11:11
membercompex8-Jan-07 11:11 
QuestionHow to implement this in WTL Pin
CodeFundu18-Mar-06 0:46
memberCodeFundu18-Mar-06 0:46 
QuestiontextColor stays grayed when Ctrl is disabled Pin
FriendOfAsherah11-Mar-06 23:22
memberFriendOfAsherah11-Mar-06 23:22 
QuestionChaning the font in ReadOnlyEdit Pin
bcamp3-Mar-06 12:50
memberbcamp3-Mar-06 12:50 
QuestionHow does it work. Pin
CastleIsle17-Feb-06 9:05
memberCastleIsle17-Feb-06 9:05 
QuestionHow to make CReadOnlyEdit in MFC ClassWizard ? Pin
krya2-Feb-06 0:43
memberkrya2-Feb-06 0:43 
AnswerRe: How to make CReadOnlyEdit in MFC ClassWizard ? Pin
CastleIsle17-Feb-06 8:29
memberCastleIsle17-Feb-06 8:29 
Generalmerci Pin
quicksoft15-Dec-05 20:45
memberquicksoft15-Dec-05 20:45 
GeneralAll this for what? Here is one liner to accomplish the same. Pin
the_gurudev29-Nov-05 19:07
memberthe_gurudev29-Nov-05 19:07 
GeneralRe: All this for what? Here is one liner to accomplish the same. Pin
chiona18-Dec-07 14:41
memberchiona18-Dec-07 14:41 
Generalinitializing background- and textcolor without control variable Pin
mekanoo9-Sep-05 14:35
membermekanoo9-Sep-05 14:35 
GeneralText Background Pin
Brian (BH)28-Jan-05 1:37
memberBrian (BH)28-Jan-05 1:37 
GeneralRe: Text Background Pin
bob169728-Nov-05 9:04
memberbob169728-Nov-05 9:04 
GeneralGreat first article! Pin
Hans Dietrich19-Jan-05 15:05
memberHans Dietrich19-Jan-05 15:05 
QuestionHow to do it in c# Pin
nagarsoft19-Jan-05 11:08
membernagarsoft19-Jan-05 11:08 
AnswerRe: How to do it in c# Pin
W. Kleinschmit19-Jan-05 23:05
memberW. Kleinschmit19-Jan-05 23:05 
GeneralRe: How to do it in c# Pin
Anonymous2-Aug-05 5:42
sussAnonymous2-Aug-05 5:42 

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