How do I change the background colour of a checkbox in MFC?

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I am designing a GUI that makes use of a checkbox. I need the colour of the chechbox, i.e. the area where the black tick appears, to change when the box is checked.

What I have tried:

I read about various approached online which suggest using the WM_CTLCOLOR message and using the OnCtlColor function, but this changes the colour immediately on initialisation. So what I did was to try and change the colour when the box is checked as follows:

void CMyAppDlg::OnBnClickedCheckTxpow()
{
	if (m_chkTxPow.GetState() == 9)
	{
		CDC *pDC;
		CWnd *pWnd;

		//pWnd->SetDlgCtrlID(IDC_CHECK_TXPOW);
		pDC = m_chkTxPow.GetDC();
		pDC->SetBkColor(RGB(0,255,0));
	}	
}

m_chkTxPow is a control variable assigned to the check box. I was trying to emulate the OnCtlColor functions available online as closely as possible. But this does not work.
Also I don't think changing the background colour affects the colour inside the box. Could anyone help me here?

Posted 20-Jun-17 19:44pm

TheLostJedi

Updated 20-Jun-17 21:49pm

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Jochen Arndt · Accepted Answer · 2017-06-20T21:49:00

There is no simple method to change the background colour of check boxes. The reason is that MFC check boxes are system controls which do not provide options to change the background colour for the arrow area and that area is not transparent.

The only option to do this is deriving a CButton class that uses owner drawing. There you can draw an unchecked box using system functions. For checked boxes fill then the background and draw the arrow manually.

This can be done for classic check boxes using CDC::DrawFrameControl, filling the background with CDC::FillSolidRect (use InflateRect(-2, -2) with the check box size) and drawing the arrow.

But applications do not use the classic style nowadays. Then you have to use DrawThemeBackground, fill the background using CDC::GradientFill, and draw the arrow shaded too. But that will not look exactly like the system drawn check boxes.

// Draw default sized check box.
// Classic        Themed
//
// LLLLLLLLLLLLW  BBBBBBBBBBBBB
// LGGGGGGGGGGSW  B           B
// LG         SW  B           B
// LG       K SW  B        G  B
// LG      KK SW  B       GG  B
// LG K   KKK SW  B  G	 GGG  B
// LG KK KKK  SW  B  GG GGG   B
// LG KKKKK   SW  B  GGGGG    B
// LG  KKK    SW  B   GGG     B
// LG   K     SW  B    G      B
// LSSSSSSSSSSSW  B           B
// WWWWWWWWWWWWW  BBBBBBBBBBBBB
// 
// L = light gray, G = dark gray, S =very light gray, B/K = black, W = white
//
// rcBox:  Rect containing the check box
// clrBk:  Background colour
// clrArr: Colour for arrow (COLOR_BTNSHADOW if disabled; else COLOR_WINDOWTEXT)

// save bk color; is changed by drawing functions
int nBkClr = pDC->GetBkColor(); 

#if 1
// Add aditional states (inactive, pushed) as required
pDC->DrawFrameControl(rcBox, DFC_BUTTON, DFCS_BUTTONCHECK);
#else
// Themed (set nThemedState accordingly):
DrawThemeBackground(m_hTheme, 
    lpDrawItemStruct->hDC, 
    BP_CHECKBOX, nThemedState, 
    &rcBox, NULL);
#endif

CRect rcBk(rcBox);
// Use -3 when themed and CBS_UNCHECKEDHOT
rcBk.InflateRect(-2, -2);
#if 1
pDC->FillSolidRect(&rcBk, clrBk);
#else
// Themed:
// Two triangles: upper left and lower right
static GRADIENT_TRIANGLE TriG[2] = { { 0, 1, 3 }, { 0, 3, 2} };
#define GetR(rgb)   ((int)((rgb) & 0xFF)) // extract R/G/B values fro COLORREF
#define GetG(rgb)   ((int)(((rgb) >> 8) & 0xFF))
#define GetB(rgb)   ((int)(((rgb) >> 16) & 0xFF))
#define Darken(a)   ((a) - ((a) >> 1)) // make R/G/B part darker
#define Brighten(a) ((a) + ((0xFF - (a)) >> 1))	// make R/G/B part brighter
#define Col16(c)    ((COLOR16)((c) << 8)) // convert R/G/B part to COLOR16 value
#define Bright16(a) (Col16(Brighten(a)))
TRIVERTEX TriV[4] = {
{rc.left, rc.top, Col16(GetR(clr)), Col16(GetG(clr)), Col16(GetB(clr)), 0},
{rc.right, rc.top, Bright16(GetR(clr)), Bright16(GetG(clr)), Bright16(GetB(clr)), 0},
{rc.left, rc.bottom, Bright16(GetR(clr)), Bright16(GetG(clr)), Bright16(GetB(clr)), 0},
{rc.right, rc.bottom, 0xff00, 0xff00, 0xff00, 0}
};
pDC->GradientFill(TriV, 4, TriG, 2, GRADIENT_FILL_TRIANGLE);
#endif

// Themed: clrArr = RGB(76, 97, 152); // not shaded!
CRect rcArr(rcBox.left + 3, // left start position
    rcBox.top + 5, // top start position
    rcBox.left + 4, // width 1 pixel
    rcBox.top + 8); // height 3 pixels
for (int i = 0; i < 7; i++) 
{
    pDC->FillSolidRect(&rcArr, clrArr);
    rcArr.OffsetRect(1, (i < 2) ? 1 : -1);
}

pDC->SetBkColor(nBkClr); // restore bk color