How to subclass CButton class for Checkbox?

[jiac]

Hi Friends,

I need to subclass a checkbox, and that is of CButton class. I tried that, and overwrite OnPaint(), however the check box disappears, I guess that is because I would need to paint the checkbox as well, well, that is beyond my knowledge, so I tried to overwrite OnCtlColor, however that doesn't get called.

One post said that I would need to set the ownerdraw flag, I tried that it doesn't work with the following:

 
m_chk.SubclassDlgItem(IDC_CHK1, this);

DWORD style = m_chk.GetStyle();
style |= BS_OWNERDRAW;
::SetWindowLong(m_chk, GWL_STYLE, style);

I placed this in OnInitDlg.

Please help, am I understanding this correctly and how to fix this.

Basically I need to change the font size/color of the checkbox text but still retain the checkbox bitmap itself since I don't know how to drawt that.

Thanks.
Jiac

[souldog]

Here is an example of a WM_PAINT handler for a class
derived from CButton. I called it CHECK_EX.

I wrote this on the spot, so I help it works.

Basically I just added a check box as normal, Set a control
variable to CHECK_EX with class wizard. The only thing I did
was handle WM_PAINT.

void CHECK_EX::OnPaint() 
{
    CPaintDC dc(this); // device context for painting
    dc.SaveDC();
    CRect rect(0,0,0,0);
    GetClientRect(&rect);
    dc.FillSolidRect(&rect, ::GetSysColor(COLOR_BTNFACE));

    CRect check_rect(rect.left, rect.top + rect.Height()/6, rect.left+ 4*rect.Height()/6, rect.bottom - rect.Height()/6);
    CRect text_rect(check_rect.right + rect.Height()/6, rect.top, rect.right, rect.bottom);

    dc.FillSolidRect(&check_rect, RGB(255,255,255));
    dc.DrawEdge(&check_rect, EDGE_SUNKEN, BF_RECT);

    //CHANGE YOUR FONT HERE
    CString text("MY STINKIN CHECK BOX");
    dc.SetBkMode(TRANSPARENT);
    dc.DrawText(text, &text_rect, DT_SINGLELINE|DT_LEFT|DT_VCENTER);

    dc.RestoreDC(-1);
    // TODO: Add your message handler code here
    
    // Do not call CButton::OnPaint() for painting messages
} 

[souldog]

OOPS... I forgot to draw the check. you need to add that, but
that just amount to drawing some lines

[jiac]

Can you also tell me how to draw the check boxes? That is the part that I have the least idea of.

Thanks.
Jiac

[VladimirF]

You could use DrawFrameControl() with DFCS_BUTTONCHECK.
However, couldn't you just set a font and color, and NOT do ownerdraw stuff?

[souldog]

I didn't know you could change the color of the text of a CButton
without making it owner drawn.
Can you? If you can then just do that.

If you do go the owner drawn route, then don't do what I did
above.

It seems that BS_AUTOCHECKBOX and BS_OWNERDRAW
do not go together well, but I did not try creating the button
outside of the resource editor

The easiest way to do owner drawn is to create a regular owner
drawn button and use DrawFrameControl() control draw the
check and box. Or you can draw the box and check yourself.
With this method you have to keep track of the state of the check yourself.
Let me know if you need it and I will give you the code

[jiac]

Can you tell me how to change the font size and font color?

In addition, for custom draw, if I were to use DFCS_BUTTONCHECK, would user's check /uncheck still be trapped? How to do that?

Thanks.
Jiac

[VladimirF]

Make a CFont data member in your dialog.
In OnInitDialog(), create the font you like (look up CreateFont(...)), and set it to be used for your checkbox (using SetFont(...)).
Create OnCtlColor() handler and check if the window pointer passed in is your CheckBox, then set the text color to whatever using pDC->SetTextColor(...);

[souldog]

Darn

I didn't realize OnCtrlColor worked when a CButton has the
BS_AUTOCHECKBOX style.

That is the way to go.

[VladimirF]

Originally posted by souldog
OnCtrlCOlor does not work for CButton objects. That is the problem

What do you mean? It works fine for me...

HBRUSH CDlg::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor)
{
    HBRUSH hbr = CDialog::OnCtlColor(pDC, pWnd, nCtlColor);

    if(pWnd == &m_Check)
    {
        pDC->SetTextColor(RGB(255,0,0));
    }
    return hbr;
}

[souldog]

Yes, I corrected myself.
Try using that method to change the text color for a regular button.

That is why i got confused

[peterbing]

BS_AUTOCHECKBOX and BS_OWNERDRAW can not work together
if you change the buttong to BS_OWNERDRAW style, it is not CheckBox any more. after you have changed the style to BS_OWNERDRAW , the function SetCheck(), GetCheck() will not work.

[souldog]

That is correct, you have to manage that yourself.
But in this case it is not needed.

[Xatrix]

Sorry for bumping this, but I have the very same problem. How can I change the color of the font and background in a CheckBox using _only_ Windows API functions/calls/messages/etc/etc.. ?

I'd apprecitate any help